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First published online 08:59 BST 15th August 2002, Copyright Derek J. Smith (Chartered Engineer). This version [2.0 - copyright] dated 09:00 BST 14th June 2018
BUT UNDER CONSTANT EXTENSION AND CORRECTION, SO CHECK AGAIN SOON
An earlier version of this material appeared in Smith (1996; Appendix F). It is repeated here with extensions and supported with hyperlinks.
Glossary of Neuropsychological Terms for Students of Speech and Language Pathology
BEFORE YOU START .....
NB1 - "Acquired" vs "Developmental" Disorders: It is standard practice within the medical professions to distinguish between "acquired" and "developmental" disorders. An acquired disorder is one which degrades a previously established skill, whilst a developmental disorder is one which prevents that skill becoming properly established in the first place. Thus if an adult loses previously established reading skills as the result of a stroke or head injury, s/he could be described as having an "acquired dyslexia", whilst if a child fell behind in learning to read (often for no immediately apparent reason) s/he could be described as having a "developmental dyslexia".
NB2 - When is it a "Dys-" and when is it an "A-"? It is frequently clinically important to distinguish total defects (of whatever) from partial defects. The naming standard for total defects is to combine the Greek prefix a- (sometimes an-) [Greek = "without"] with some sort of root describing the ability in question. Thus a total inability to recognise a stimulus object is termed an agnosia, because it is an absence of gnosis [Greek = "knowing"]. The standard for partial defects is to use the prefix "dys-" (as in "dysfunctional" or "dysentery"), and the clear implication is then that the ability in question is merely disordered rather than totally absent. Properly applied, the dys-/a- naming system ought to allow us to distinguish between apraxia, a total lack of voluntary movement, and dyspraxia, a partial lack, or between anarthria, a total lack of joint articulation, and dysarthria, a partial lack, or between alexia, a total inability to read, and dyslexia, a partial lack, and so on. Sadly, the standard is less than reliably enforced, and the terminology is used sufficiently loosely to render the partial-total distinction quite unsafe. In the glossary below we therefore use the word-pairs aphasia-dysphasia, apraxia-dyspraxia, and anarthria-dysarthria fully interchangeably.
Abstraction: See the detailed definition in our Main Glossary (AB).
Abulia: "Reduction in speech, movement, thought, and emotional reaction; a common result of bilateral frontal lobe disease" (Medical Search Engine, 2004).
Access Dysphasia: A type of dysphasia described by Warrington and McCarthy (1987) and characterised by difficulty retrieving semantic information from memory rather than by the loss of the underlying memory traces in any absolute sense. A difficulty in indexing that which is still there. [For an introduction to the complexities of indexing memory content (and therefore of the comparative ease of "mislaying" it), see Morton, Hammersley, and Bekerian (1985).]
Acquired Dyscalculia: [See firstly NB1 above.] A dyscalculia arising in a previously skilled (and thus usually adult) subject, as a result of brain injury or disease. [See Gerstmann's syndrome.]
Acquired Dyslexia: [See firstly NB1 above.] A dyslexia arising in a previously skilled (and thus usually adult) reader, as a result of brain injury or disease. The study of acquired dyslexia goes back to the age of the diagram makers, and clinical case studies have identified a number of subtypes, notably deep dyslexia and surface dyslexia. Modern interest in this topic was sparked by Marshall and Newcombe (1966, 1973). The essence of both classical and modern explanations is that normal reading ability reflects the coordinated simultaneous functioning of a number of discrete cognitive processes [see, for example, Charcot (1883) and Marshall and Newcombe (1973), respectively]. Acquired dyslexia in intelligent machines has been studied since the late 1980s by connectionists [see, for example, Hinton, Plaut, and Shallice (1993)].
Acute Disorder: A disorder posing an immediate threat. E.g. acute appendicitis. [Compare chronic disorder.]
Aggressive Disorder: A disorder of rapid onset or progression. Some progressive disorders can be more aggressive than others.
Agnosia: Strictly speaking, a total failure of gnosis. A state of not knowing what something is, or is for, in a confrontational naming task. [See now finger agnosia.]
Agrammatism: Defective syntax in speech (but not, curiously enough, in automatic speech). A frequent sign of Broca's aphasia. [There is a longer discussion of agrammatism in Section 6.5 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Alexia: Strictly speaking, a total inability to read the written word but with preserved visual perception of objects and pictures. [See NB2 above, and then compare dyslexia.]
Alzheimer's Disease: [See firstly dementia; also known as dementia of Alzheimer's type (DAT).] Alzheimer's disease results from a remorselessly progressive loss of neural tissue at a microscopic level. Neurons are gradually replaced by non-excitable "plaques and tangles" until eventually what first shows itself clinically as mild forgetfulness advances into a total breakdown of all cognitive functions. [Factsheet]
Amnesia: The general term for a defect of long-term memory, be it neurogenic or psychogenic in origin. Neuropsychology deals mainly with the amnesic syndrome and frontal amnesia. [See NB2 above: for some reason, the corresponding term dysmnesia is rarely seen.]
Amnesic Syndrome: An amnesic state arising from a variety of causes, and characterised by a severe-to-total anterograde amnesia, accompanied by some degree of retrograde amnesia and a package of non-amnesic symptoms and signs such as attention deficits, irritability, and general emotional lability. Short-term memory, curiously enough, is intact up to 30 seconds or so, and general intelligence remains at the premorbid level. The syndrome is correlated anatomically with bilateral lesions of either the hippocampal regions or the mammillary bodies.
Anarthria: Strictly speaking, a total inability to carry out a skilled muscle movement, or, in the context of communication, a total inability to produce speech. [See NB2 above, and then compare dysarthria.]
Aneurism: A congenital weakness in an artery wall, and therefore a likely point of eventual rupture and haemorrhage. Where the artery concerned is a cerebral artery, this is a predisposing factor to a haemorrhagic CVA.
Angular Gyrus: Gyrus at the junction of the parietal, temporal, and occipital lobes, and therefore admirably placed to support simultaneous interpretation of (respectively) somaesthetic, auditory, and visual information. [See Brodmann's Area 39 on Kleist's (1934) cortical localisation map. See also Gerstmann's syndrome.]
Anomia (1): A clinical sign readily discovered using a confrontational naming task. A naming disability very common in all the aphasias, and one of the key factors in the aphasic's reduced communicative success. A difficulty in retrieving words from the lexicon (1), although it is unclear whether this is due to damage to the lexicon itself, or to defective access to it. Nine different subtypes of anomia were identified by Benson (1979), including category-specific anomia, modality-specific anomia, semantic anomia, word production anomia, and word selection anomia. [See NB2 above: for some reason, the corresponding term dysnomia is rarely seen.]
Anomia (2): A clinical syndrome. A type of aphasia (anomic aphasia) wherein anomia (1) is the predominant presenting sign.
Anomic Aphasia: See anomia (2).
Anterior Cingulate Gyrus: This is the proportion of the cingulate gyrus which is located anterior to the corpus callosum, that is to say, at Brodmann's Area #24 on the medial aspect of the Kleist (1934) brain map [click here, and look at the stippled area, right of centre, on the lower diagram]. This is an area of major importance in studies of the self and consciousness, because it seems to be heavily involved in "executive functions such as error detection and response monitoring" (Badgaiyan, 2000/2004 online, p39). Indeed the cingulate is involved in so many executive functions that it may be "considered crucial for execution of supervisory function" (Ibid.). Recent research also implicates the anterior cingulate gyrus in the selection of the appropriate response under conditions of doubt (see, for example, Pardo et al, 1990), and Mesulam (1995) has found contralateral symptoms of "motivational neglect" with unilateral lesions of the anterior cingulate cortex.
Anterograde Amnesia: An amnesia which acts forwards in time from the moment of insult, and which is therefore characterised by a difficulty in consolidating new experience, that is to say, patients can have experiences, but they cannot recall them more than a few seconds after the event. They can therefore quite cheerfully have the same experiences over and over again without realising it. [Compare retrograde amnesia.] [Internet cases]
Aphasia: Generic term for a wide variety of acquired neurogenic language disorders. An impairment to a greater or lesser extent of higher cognitive language processing, rather than of the more peripheral sensory and motor systems. Alternatively, "a multimodality reduction in capacity to decode (interpret) and encode (formulate) meaningful linguistic elements" (Darley, Aronson, and Brown, 1975, pp1-2). In Wernicke's aphasia, for example, words are poorly understood, despite an intact auditory system. Aphasias are conventionally divided into fluent and non-fluent types, and then into specific subtype syndromes. [See NB2 above.] [See separately access dysphasia, anomic aphasia, Broca's aphasia, conduction aphasia, global aphasia, jargon aphasia, optic aphasia, thalamic aphasia, transcortical motor aphasia, transcortical sensory aphasia, and Wernicke's aphasia.]
Apraxia: Strictly speaking, a total inability to initiate voluntary motor movements, despite intact motor pathways. [See NB2 above, and then compare dyspraxia.]
Asperger's Disorder / Syndrome: See this entry in the companion glossary on "Self and Consciousness".
Ataxia: An inability to coordinate skeletal muscular activity, leading to unsteadiness and defects of balance.
Ataxic Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Athetosis: [Greek = "without fixed position"] Term coined by Hammond (1871) to describe a state of continual motion (of hand, limb, etc.), often slow and writhing.
Autism: This from Baron-Cohen (1989): "Autism is a pervasive developmental disorder which begins in the first 36 months of life . Symptoms include deficits in the pragmatic [Psycholinguistics Glossary] aspects of language , an absence of symbolic play , and the presence of ritualistic behaviour . Autistic children also suffer a severe impairment in their ability to relate socially." Autism has been a popular area of study of late, because the aforementioned pragmatic deficits generated a popular cognitive deficit explanation. As formulated initially by Baron-Cohen, Leslie, and Frith (1985), this explanation asserts that all the categories of autistic symptom can be traced back ultimately to a specific underlying disorder of second order representation, also referred to as an inability to form a theory of mind, or as mindblindness. As a result, autism studies are of as much interest to philosophers, psycholinguists, and neurobiologists, as they are to paediatric clinicians.
Auto-Association: Hypothetically, auto-association is one of the basic properties of biological cell assemblies or computerised neural networks. The process detects the stable patterns in incoming stimulation, and creates an inter-associated set of neurons particular to each "constant form" within that stimulation. The resulting "learned" network is stable, exhibits part-to-whole retrieval, and can be further developed by experience. The concept is invoked in the distributed memory theory of Allport (1985), and provides a potential micro-mechanism for the entire psychological phenomenon of abstraction.
Automatic Speech: Over-learned and familiar phrases such as cursing, counting, reciting, and rhyme. Can be retained in Broca's aphasia and dementia even when non-automatic speech is affected. Presumably initiated, therefore, in an area other than Broca's Area, and possibly stored in the lexicon as single units despite being made up from individual words stored individually! [For an example, see McCarthy and Warrington (1984).]
Ballism: [Greek ballein = "to throw"] A clinical sign. Uncontrolled flailing movements of arms or legs.
Benign: Of tumours, one which is not cancerous. [Compare malignant.]
Blindsight: The term describing any residual visual abilities following damage to either the geniculo-striate pathway and-or cortical area 17. Such residual abilities are fairly rudimentary aspects of vision such as the automatic shifting of gaze towards a light, and their effects are typically unconscious. [Further details and demonstration.]
Boston School: Doctrine of aphasiology which insists on mapping aphasic symptoms closely onto brain areas. [Compare globalist school.]
Bovine Spongiform Encephalopathy (BSE): An untreatable progressive encephalopathy of cattle, characterised by a fairly aggressive deterioration of brain tissue, and probably due to the action of a prion, an abnormal protein. Also possibly transferrable to humans as Creutzfeld-Jacob disease.
Broca's Aphasia: A non-fluent aphasia characterised by effortful and halting speech, reduced phrase length, prosodic disturbance, and awkward articulation. Frequently shows dyspraxia of speech, long voice onset times, agrammatism, anomia (1), paraphasia, telegraphic speech, intrusive vowels, hesitations, consonant substitutions, repetition difficulties, and writing difficulties. Auditory comprehension is relatively intact (unlike Wernicke's aphasia), as is the willingness to engage in spontaneous interaction (unlike transcortical motor aphasia). Automatic speech is commonly spared. [See also Lichtheim's house.]
Broca's Area: The third frontal convolution of the left hemisphere, and the site of a classic Broca's aphasia. The area where Broca's patient, Leborgne, had his lesion. Consists of Brodmann's Areas 44 and 45 [to see where these are on the cortical map, click here].
BSE: See bovine spongiform encephalopathy.
Bulbar Palsy: Facial and/or pharyngeal palsy resulting from damage to medullary lower motor neurons. [Compare pseudobulbar palsy.]
Cancer: An abnormal and uncontrolled process of cell division leading to the formation of a life-threatening growth. Can be sub-typed into carcinomas and sarcomas. Characterised by being able (a) to invade and destroy surrounding healthy tissue, and (b) to create metastases.
Carcinoma: A cancer of epithelial tissue. [Compare sarcoma.]
Category-Specific Anomia: One of the nine clinically distinct subtypes of anomia (1) recognised by Benson (1979). A category-specific impairment in which there is a naming defect for some classes of objects but not for others. Such impairments might be for colours or uses, or for fruit and vegetables, or personal names, and are generally held to indicate some sort of categorical zoning of the lexicon (1).
Category-Specific Impairment: A class of cognitive impairment where the severity of the defect (a) depends in large part upon the semantic or grammatical nature of the test item, and (b) is common to other test items from the same semantic or grammatical category. Often presents as a selective anomia or agnosia, and is commonly taken as reflecting the underlying organisation of the lexicon. For a brief review of the history of this type of defect, see Warrington and Shallice (1984), and for a useful explanatory diagram, see Allport 1985.
Cell Assembly: A collection of interconnected-by-experience neurons capable of functioning as a physiological memory of that experience. [For a fuller definition and useful onward links, see our Main Glossary (C).]
Cerebro-Vascular Accident (CVA): Brain damage arising from an acute episode of cerebro-vascular disease, with associated physical and psychological symptoms. "A syndrome characterised by rapidly developing clinical symptoms and/or signs of focal loss of cerebral function, in which symptoms last more than 24 hours [compare transient ischaemic attack]or lead to death, with no apparent cause other than that it is of vascular origin" (Rudd and Wolfe, 2002/2004 online). Occurs in two basic forms, namely the thrombotic form, resulting from a blood vessel blockage (perhaps as a result of an embolism or thrombosis), and the haemorrhagic form, resulting from a blood vessel bleed (perhaps as a result of an aneurism) [see Rudd and Wolfe, op. cit., for a more detailed classification]. Given the nature of the brain's blood supply, an infarct at one point will cause cell death [necrosis] at any point "upstream" which does not have an alternative blood supply, and given the nature of cellular chemistry that necrosis can itself cause diaschisis.
Cerebro-Vascular Disease: Deterioration of the brain's circulatory system, typically as the result of a progressive disorder. A common precursor to a cerebro-vascular accident.
CHI: See closed head injury.
Chorea: [Greek choreia = "dance"] Poorly controlled skeletal movements, giving rise to irregular and involuntary lurching while walking, as well as intermittent grimacing.
Chronic Disorder: A permanent or long-standing disorder which poses no immediate threat. E.g. chronic bronchitis. [Compare acute disorder.]
Circumlocution: Finding another way to say something when the word you really wanted to say is unavailable to the speech production process as a result of anomia (1).
Closed Head Injury (CHI): A class of traumatic head injury. A "blunt instrument" bang on the head, such as occurs in boxing, some road traffic accidents, and many household or day-to-day blows to the head. Damages brain tissue indirectly, that is to say, by shaking it about. [See also concussion, and compare penetrating head injury.]
Coma: A period of profound and prolonged unconsciousness following disease or injury.
Concussion: The clinical manifestation of the diaschisis, oedema, and other sequelae of a traumatic head injury; a period of raised intracranial pressure due to same, which can itself threaten to do yet further damage.
Conduction Aphasia: A fluent aphasia characterised by an impairment in verbal repetition far out of proportion to any fluency or comprehension deficits. The syndrome was predicted by Wernicke (1874) and confirmed by Lichtheim (1885). So named because although the verbal repetition task involves both comprehension and production processes at the same time, only the communication link between the two seems to be at fault. Symptoms include paraphasias and anomia (1) in a context of fluent melodic speech. Voice onset time, grammar, and comprehension are not impaired. Conduction aphasias are commonly attributed to lesions of the white matter arcuate fasciculus connecting Broca's area and Wernicke's area. [See also Lichtheim's house.]
Confabulation: [See firstly frontal lobe syndrome and dysexecutive syndrome.] An attempt to explain present evidence to a present audience but without a true recollection to go on [compare false recollection]. If the confabulation is in any way grandiose or unreasonable then it is termed fantastic confabulation, but if it is reasonable-but-just-inaccurate it is termed momentary confabulation (McCarthy and Warrington, 1990). [There is a longer discussion of confabulation in Section 9 of our e-paper on "From Frontal Lobe Syndrome to Dysexecutive Syndrome".]
Confrontational Naming Task: A clinical assessment test requiring the patient to name objects by sight, sound, or touch, pictures by sight, and general sounds, tastes, and smells as appropriate. By its nature, a good screening test for anomia (1). [See also cueing.]
Connectionism: The philosophical doctrine that cognition can be modelled (and therefore better understood) by connecting up artificial neurons, either in fact, or in simulation on a computer, and the practical science thereof. [For a longer introduction to this topic, see our e-paper on "Connectionism".]
Connectionist: One who practices connectionism.
Creutzfeld-Jakob Disease (CJD): A progressive encephalopathy of humans, possibly a variant of bovine spongiform encephalopathy.
Crossed Aphasia: A right hemisphere aphasia. Occurs in 1-2% of all aphasias, and characterised by confusion, memory and attention defects, and personality change (in addition to the usual language deficits). Agrammatism is common, but comprehension and naming tend to be preserved.
Cueing: A way of helping patients if they are having difficulty with a confrontational naming task. Cueing involves prompting them in some way, and the relative efficacy of different types of cues often reflects upon the organisation of the normal naming process. [See now first letter cueing, phonemic cueing, semantic cueing, and silent articulatory cueing.]
CVA: See cerebro-vascular accident.
Deep Dyslexia: A subtype of acquired dyslexia characterised primarily by difficulties at the word meaning level when reading aloud [compare surface dyslexia]. Typical problems include (a) semantic paralexical confusions (e.g. reading "stamps" for "postage"), (b) relative difficulty with abstract nouns compared to concrete nouns, and (c) poor reading of unfamiliar words or non-words. Coltheart (1980) explains the paralexias by arguing that one of the right hemisphere's main jobs is to establish the "superordinate semantic category" to which a printed word belongs. When a normal brain reads out loud, each stimulus word propagates firstly from the visual cortex to Wernicke's area, and then from Wernicke's Area to Broca's area. At the same time, it propagates into the right hemisphere to activate the appropriate categorial nodes in the broader semantic network. For the stimulus word STONE, this might be the node for [minerals | fragments of | small], and the critical point is that the identical categorial area would also be stimulated by such stimulus words as "GRAVEL", "PEBBLE", "COBBLE", etc. In a deep dyslexic subject, on the other hand, the direct dominant hemisphere pathway is presumed dysfunctional, and so the activation of Broca's Area is forced to go via the right hemisphere, which knows only the general word category of the stimulus word. [There is a longer explanation of Coltheart's views on this subject, complete with supporting diagram, in our e-paper on "Dyslexia and the Cognitive Science of Reading and Writing".] More recently, the connectionists Hinton, Plaut, and Shallice (1993) have offered a novel additional insight into the phenomenon, derived from observations of dyslexia-like symptoms in an artificial processing network. They argue that one of the necessary aspects of semantic encoding is the need to minimise confusion between similar word meanings, and they postulate an array of "cleanup" memory attached to, and supporting, the main semantic store. When this auxiliary memory is damaged, the accuracy of indexing that main store degrades even though its content is intact.
Déja Vu: [French = "already seen"] An inappropriate perceptual quale (plural = qualia). The erroneous belief that you have seen something or been somewhere before, when factually you have not. This is a truly puzzling symptom because it challenges the most fundamental definitions of an intact memory. William James, for example, defined memory as being accompanied by "the additional consciousness that we have thought or experienced it before" (James, 1890, p648; italics original). In cases of déja vu, however, this additional consciousness exists when logically it should not.
Dementia: [Literally, to lose one's mind.] A generic term for a number of progressive medical conditions, all characterised by a gradual loss of perceptual, memory, and higher cognitive functions. The best known dementia is Alzheimer's disease, but see also multiple-infarct dementia and compare senile dementia.
Developmental Dyslexia: [See firstly NB1 above.] A dyslexia arising in someone learning to read (and thus usually pre-adult), possibly as a result of brain injury or disease. The study of developmental dyslexia goes back to the late 19th century, when Pringle-Morgan (1896) reported it in the case of Percy, a 14-year-old boy. Modern interest in this topic was sparked by the sustained controversy over recent decades over poor national literacy levels, and the failure of a parade of educational initiatives to improve matters. [There is a longer introduction to this subject in our e-paper on "Dyslexia and the Cognitive Science of Reading and Writing".]
Developmental Verbal Dyspraxia: [See firstly NB1 above.] The developmental form of dyspraxia of speech.
Diagram Makers: School of nineteenth century aphasiologists who argued strongly for the precise localisation of language functions. Typically Wernicke (1874) and Lichtheim (1885). Lichtheim's house is a good example of the diagrams drawn by the diagram makers.
Diaschisis: Neural shock, that is to say, the temporary suppression of response in healthy neural tissue close to the site of an actual lesion. Typically, this will be due to swelling at, or chemical contamination from, the primary site. Either way, it results in behavioural deficits greater than would otherwise be expected, but in respect of which some degree of spontaneous recovery may confidently be expected.
Disconnection Syndrome: A neurogenic disorder (of language or whatever) caused by subcortical (white matter) damage rather than by cortical (grey matter) damage. This means that the separate modules of a distributed (i.e. "modular") processing system can remain physically intact within themselves, but lose their ability to interact meaningfully with each other, thus degrading the overall performance of the system in question. Conduction aphasia is a typical disconnection syndrome.
Disease: "A disorder with a specific cause and recognisable signs and symptoms; any bodily abnormality or failure to function properly, except that resulting directly from physical injury" (Oxford Dictionary for Nurses).
Dissociation: See the more detailed coverage of this topic in the companion Mental Philosophy Glossary.
Dissociation (of Function): The selective loss of a particular cognitive ability following a localised brain injury, so named because the failing ability "dissociates"- that is to say, moves away - from the remaining intact abilities. One of the classic examples of a dissociation is the disproportionate damage to the fluency of language production produced by lesions in Broca's Area. [See now double dissociation.]
Double Dissociation: [See firstly dissociation.] Term coined by Bagshaw and Pribram (1965) and popularised by Warrington and Rabin (1970) to refer to two in-some-way complementary dissociations. The classic example of a double dissociation is that between the sentence production deficits found with lesions in Broca's Area and the sentence comprehension deficits subsequently found with lesions in Wernicke's Area. The complementarity derives from the fact that the earlier discovery in some way directly invited the search for the second.
Dysarthria: Strictly speaking, a less than total impairment of the ability to move a muscle group despite an otherwise adequate intention, or - in the context of communication - an impaired inability to produce speech. In this latter respect, "a group of speech disorders resulting from disturbances in muscular control" (Darley, Aronson, and Brown, 1975, pp1-2). [Compare anarthria.] [See separately ataxic dysarthria, flaccid dysarthria, hyperkinetic dysarthria, hypokinetic dysarthria, mixed dysarthria, and spastic dysarthria.]
Dyscalculia: Strictly speaking, a less than total defect of number processing, with both acquired and developmental forms. [There is a longer discussion of the brain's involvement in numeracy in our e-paper on "The Psychology of Numeracy".]
Dyslexia: Strictly speaking, a less than total defect of written language processing, most conveniently dealt with under two major subtypes, namely acquired dyslexia and developmental dyslexia.
Dysnomia: Avoid - use anomia instead.
Dysphasia: Strictly speaking, a less than total aphasia, but in practice a simple synonym for aphasia. [See NB2 above.]
Dyspraxia: Strictly speaking, a less than total defect of praxis, common as a result of CVA or other pathology. An "inability to act or to move various parts of the body in a purposeful manner, although the power of movement is intact. There is no paralysis and the patient understands what is required of him; yet he cannot execute the action he wishes to perform" (Head, 1926, p94). In children, often known as clumsy child syndrome or minimal brain dysfunction.
Dyspraxia of Speech: A subset of the dyspraxias, presenting as a specific difficulty in initiating vocalisation, accompanied by effortful production and defective prosodic quality. A disorder of "brain circuits devoted specifically to the programming of articulatory movements" (Darley, Aronson, and Brown, 1975, pp1-2). General intellectual level is not necessarily impaired. In children, often known as developmental verbal dyspraxia. [There is a longer discussion of dyspraxia of speech in Section 6.7 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Echolalia: A clinical sign. The automatic repetition of all that the patient hears. Frequently found in transcortical motor aphasia and Tourette's Syndrome.
Echopraxia: A clinical sign. The automatic mimicking of the physical movements of others. Frequently found in Tourette's Syndrome.
Embolism: A clot or other floating obstruction in a blood vessel. Can cause a thrombotic CVA.
Encephalitis: A viral or bacterial infection of the brain or brainstem, resulting in inflammation and cell death.
Encephalopathy: Cell death degeneration of the brain or brainstem.
Epiphenomenalism: The doctrine that psychological consciousness is an incidental by-product (i.e. epi-phenomenon) of neural activity, but has no causal influence upon it.
False Recollection: A false memory. An act of apparent recall; one which is perceived as genuinely having happened, but which does not, in fact, reference a real occurrence. [Compare confabulation.]
First Letter Cueing: A type of cueing. Involves giving the initial letter of the target word in the hope that this will help the patient access the lost speech output patterns (e.g. "It begins with a K [pronounced "kay"] ....."). Make sure you say the letter name, and not the phonetic sound of the letter. [Compare phonemic cueing, semantic cueing and silent articulatory cueing.]
Finger Agnosia: [See firstly agnosia.] Finger agnosia is a mental confusion over the location of your fingers in space, by sight, and/or across the left-right divide. For its role in Gerstmann's Syndrome, see the companion resource "The Psychology of Numeracy", and for how it can be detected, see "A Gentle Introduction to Finger Agnosia".
First Order Representation: See representation, first order.
Flaccid Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Fluent Aphasia: An aphasia with generally retained word production ability (although nonetheless frequently paraphasic or jargonaphasic). Three types of aphasia are usually classed as fluent, namely Wernicke's aphasia, conduction aphasia, and transcortical sensory aphasia. [Compare non-fluent aphasia.]
Frontal Amnesia: An amnesic state associated with damage to the frontal lobes, and characterised by confabulations and difficulties with problem solving tasks requiring forward planning. [There is a longer discussion of the memory correlates of frontal lobe injury in our e-paper on "From Frontal Lobe Syndrome to Dysexecutive Syndrome".]
Fugue: The term "fugue" has long been applied to transient amnesic states in which there is loss of access to either the semantic or episodic aspects of the self, and which commonly results in the sufferer wandering aimlessly away from their normal workplace or home. This clinical pattern of signs was elevated by the DSM-IV into "dissociative fugue", one of the four specific dissociative disorders, describing it as follows .....
"The essential feature of Dissociative Fugue is sudden, unexpected travel away from home or one's customary place of daily activities, with inability to recall some or all of one's past (Criterion A). This is accompanied by confusion about personal identity or even the assumption of a new identity (Criterion B). [.....] Travel may range from brief trips over relatively short periods of time (i.e., hours or days) to complex, complex, usually unobtrusive wandering over long time periods (e.g., weeks or months), with some individuals reportedly crossing numerous national borders and traveling thousands of miles. During a fugue, individuals may appear to be without psychopathology and generally do not attract attention" (DSM-IV, p524).
Functionalism (1): The classical philosophical doctrine that the mind's mental operations exist (and implicitly do not come cheaply in the first place) for their practical value in satisfying the needs of a vulnerable organism in an hostile environment. Arose around the turn of the 19th/20th centuries from the writings of John Dewey and James Angell at the University of Chicago. [Full history]
Functionalism (2): Modern form of functionalism (1). The philosophical doctrine that there is value to be had from analysing cognitive processes in isolation, i.e. separated from considerations of brain anatomy. Borrows heavily from computer science (hence cannot predate the computer era). Arose during the 1950s from early theories of attention and memory, and now typified by the various competing logogen theories. Clearly seen in the writings of David Marr, and especially in his notion of the computational level of cognition (Marr, 1982). [Full discussion. For a nice introduction to Marr's work, see McClamrock (1991/2004 online).]
Gerstmann's Syndrome: Gerstmann (1930) described an acquired neurogenic syndrome in which four distinct signs tended to co-occur. These were (a) "finger agnosia", an inability to tell one finger from another, (b) right-left disorientation, (c) writing difficulties, and (d) dyscalculia. This syndrome seemed to follow damage centred on the angular gyrus of the dominant hemisphere.
Global Aphasia: A severe-to-total impairment of all communicative (if not all cognitive) ability. Common just after a CVA or THI, but frequently relieved by spontaneous recovery. Best described by the everyday phrase "the lights are on but there's nobody in"!
Globalist School: Those aphasiologists - including Jackson, Freud, and many others - who believe(d) that the brain works as a holistic system, and who therefore caution(ed) against trying to attribute specific functions to specific areas. [Compare diagram makers and Boston school.]
Gnosis: The word "gnosis" means knowing something for what it is, recognising it, evaluating its significance, knowing what it does and - perhaps more importantly - what you should do about it. States of gnosis are the logical end-result of the broader process of perception, and are by that token quite vulnerable to brain damage. If impaired, the resulting condition is known as an agnosia.
Herpes Simplex Encephalitis (HSE): An infection of the brain by the herpes simplex virus.
HSE: See herpes simplex encephalitis.
"Hunting": An inability on the part of a control system to establish a smooth level of performance, and believed to be responsible in biological systems for clinical signs such as tremor.
Hyperkinetic Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Hypokinetic Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Infarct: An area of cardiac, neural, or other cell death (necrosis) following interruption of blood supply (ischaemia), perhaps due to thrombosis, embolism, or haemorrhage. A cerebral infarct would be expected following a CVA.
Infection: "Invasion of the body by harmful organisms" (Oxford Dictionary for Nurses).
Injury: See trauma (1).
Insult: In its clinical sense, that which brought about the current disorder, be it disease or injury.
Ischaemia: Reduced blood flow. Relevant within neuropsychology when it affects the brain's blood supply, and then potentially a sign of cerebro-vascular disease. [See now transient ischaemic attack.].
Jargon Aphasia: (Sometimes jargonaphasia.) An aphasia in which speech is produced rapidly and incomprehensibly, with frequent neologisms. Occurs as three subtypes, namely semantic jargon, neologistic jargon, and phonemic jargon. [There is a longer discussion of jargon aphasia in Section 6.6 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Korsakow's Syndrome: See Wernicke-Korsakow Syndrome.
Lesion: Any area of damaged tissue as a result of disease or trauma.
Lesion Momentum: The speed of development of a lesion (e.g. CVA or tumour). Relevant to aphasiology because the severity of the resulting impairment often seems to be as much determined by lesion momentum as by that lesion's actual extent.
Lexicon (1): Term used by linguists to denote the mental word store in its entirety. [Compare lexicon (2) and semantic lexicon.] [There is an expanded definition of this term in our psycholinguistics glossary.]
Lexicon (2): Term used by cognitive neuropsychologists to denote a word form store within a specific information processing route. [Compare lexicon (1).] [There is an expanded definition of this term in our psycholinguistics glossary.]
Lichtheim's house: Diagram by Lichtheim (1885). Relates different types of aphasia to a proposed "three-box" functional organisation of language in the brain.
Logogen: Term coined by Morton (e.g. 1979) for a word form and-or the store in which it is held. Every discernible type of word form is allocated its own logogen, meaning that there are several such stores. For example, input and output word forms would be in different stores because one was inherently perceptual (sound or shape) and one inherently behavioural (phonatory or writing skill). Similarly, with the spoken and the written word. Same thing as a lexicon (2).
Logorrhoea: Word diarrhoea. Incessant chatter.
Lower Motor Neuron: See our e-handout on "The Pyramidal and Extrapyramidal Motor Systems".
Malignant: Of tumours, one which is cancerous. [Compare benign.]
Matching-to-Sample: A method of response used with patients who would otherwise be unable to respond verbally. Patients are presented with stimuli in the modality under investigation (ie as the spoken word, written word, physical object, or whatever), and allowed to respond by pointing towards the desired response in an array of possible responses. [For an example, see Warrington and McCarthy's (1987) work with patient YOT.]
Metastasis: (Plural metastases, or colloquially "mets".) A "secondary" cancer, that is to say, one which has "spread" some distance away from a primary site, and frequently to a totally different organ.
MID: See multiple infarct dementia.
Mindblindness: See the detailed definition in our Psycholinguistics Glossary.
Mixed Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Modality-Specific Anomia: One of the nine clinically distinct subtypes of anomia (1) recognised by Benson (1979). An anomia in which there is a naming defect for objects presented in one sensory modality, but not for the same objects in a different modality. Gnosis is intact. In optic aphasia, for example, a wristwatch might fail to elicit the name word if shown visually, but be immediately named (by touch) if physically placed in the patient's hand.
Multiple-Infarct Dementia (MID): [See firstly cerebro-vascular accident and dementia.] A dementia-like gradual deterioration of cognitive function resulting from a succession of small strokes (rather than from the "plaques" associated with Alzheimer's disease).
Necrosis: Any area of cell death, possibly an infarct.
Neologism: An idiosyncratic word. A jargon word, not found in any dictionary. [Compare paraphasia, where the selection is a real word, but not the right one.]
Neologistic Jargon: One of three clinically distinct subtypes of jargon aphasia. Jargon characterised by the frequent use of neologisms. [Compare phonemic jargon and semantic jargon.]
Neoplasm: [Literally "new structure".] Alternative term for cancer.
Nervous System Divisions and Subdivisions: Here are the components of the generic vertebrate nervous system, shown as an indented hierarchy .....
Forebrain ( or prosencephalon)
Cerebrum (or telencephalon)
Cerebral Hemispheres (left and right)
Cerebral White Matter
Basal Ganglia (or “Corpus Striatum”)
various component nuclei
various component nuclei
Midbrain (or Mesencephalon)
Midbrain Grey Matter
Tegmentum/Reticular Formation (higher)
Nuclei of extrapyramidal system
Cranial Nerve Nuclei III and IV
Midbrain White Matter
complex of local connections, plus.....
complex of ascending/descending tracts passing through
Hindbrain (or Rhombencephalon)
Hindbrain Grey Matter
Reticular Formation (lower)
Cranial Nerve Nuclei V to XII
major sensory relay nuclei
major vital and semi-vital nuclei
Hindbrain White Matter
complex of local connections, plus.....
complex of ascending/descending tracts passing through
Spinal Grey Matter
Spinal White Matter
various component tracts
Somatic Branch (some cranial and spinal nerves)
somatic and mixed cranial nerves
somatic spinal nerves
Autonomic Branch (some cranial and spinal nerves)
autonomic and mixed cranial nerves (especially CN.X)
autonomic spinal nerves
Neural Network: An artificial cell assembly. [See the detailed definition in our Main Glossary (MNO).]
Neuromarketing: This is the name given to the application of neuroscience by marketing professionals. [See the detailed definition in our Main Glossary (MNO).]
Non-Fluent Aphasia: An aphasia characterised by impaired word production. Two types of aphasia are usually classed as non-fluent, namely Broca's aphasia and transcortical motor aphasia. [Compare fluent aphasia.]
Oedema: Tissue swelling following damage. A frequent complication of a cerebro-vascular accident or closed head injury.
Optic Aphasia: An aphasia characterised by a modality-specific anomia, that is to say, by problems naming pictorially presented stimuli, but with preserved tactile recognition and generally intact visual gnosis.
Organic Disorder: A disorder of the physical body, such as occurs with an infection or physical trauma. Compare and contrast psychogenic disorders.
Paralexia: A lexical selection error during reading out loud [compare paraphasia]. The production of one word when another is meant. Occurs as two sub-types, namely semantic paralexia and phonemic paralexia. [See Marshall and Newcombe (1973) for detailed case examples and discussion.]
Parallel Distributed Processing (PDP): A computing architecture which arranges many processors in such a way that they can each handle part of a large problem at the same time [see, for example, the design of the CDC 6600 supercomputer as detailed in Section 1.5 of our e-paper on "Short-Term Memory Subtypes in Computing and Artificial Intelligence" (Part 5)]. When done properly, PDP architectures make for a quicker solution than would otherwise have been possible (processing needs to be meticulously co-ordinated, however). In fact, the concept has been around since the days of the diagram makers, although the particular name for it was not coined until the mid-1980s by David E. Rumelhart and James L. McClelland.
Paramnesia: An incomplete amnesia characterised by disorganised, contradictory, and muddled recall (especially of times and places), rather than complete non-recall. [See confabulation, deja vu, and false recollection.]
Paraneoplastic Limbic Encephalitis (PLE): A degenerative gliosis, centred on the medial temporal lobe, and arising as a result of a cancer elsewhere in the body (e.g. lung). Presents with a severe anterograde amnesia and emotional lability, but relatively intact intelligence, language, and short-term memory.
Paraphasia: A lexical selection error during conversational speech [compare paralexia]. The production of one word when another is meant. Occurs as two sub-types, namely semantic paraphasia and phonemic paraphasia. [Compare neologism.]
Paresis: State of reduced power to, and fine control of, the skeletal muscles. Occurs as a result of damage to the pathways exciting muscular contraction. [Compare spasticity.]
Penetrating Head Injury: A class of traumatic head injury. A "sharp instrument" bang on the head, such as occurs with pointed weapons, gunshot wounds, shrapnel, etc. Involves penetration of the skull and meningeal layers, and direct damage to brain tissue. [Compare closed head injury.]
Peripheral Dyslexia: A subtype of acquired dyslexia proposed by Shallice and Warrington (1980), wherein the main deficit is in early visual analysis. [Compare deep dyslexia.]
Perseveration: [See firstly frontal lobe syndrome and dysexecutive syndrome.] A motor system problem in which the accurate production of a complex behaviour is corrupted by residual elements from an earlier behaviour. Perseveration is a common sign of dysexecutive syndrome, and may manifest itself as repetitive copying of letters or shapes in a pen-and-paper copying task, or as an inability to switch sorting criteria in one of the frontal battery sorting tasks. Goldberg and Costa (1986) identify a number of perseveration subtypes, from a low-level "inability to terminate the execution of elementary movements" (p50) to a "higher-order cortical perseveration" in which patients "cannot shift completely from one motor task to another" (p50). To cope with this complexity, they recommend "a hierarchical model of executive function" (p54). [We give several examples of perseveration in our e-paper on "From Frontal Lobe Syndrome to Dysexecutive Syndrome".]
Phonemic Cueing: A type of cueing. Involves giving the initial sound(s) of the target word in the hope that this will help the patient access the lost speech output patterns (e.g. "It begins with a /k/ ....."). Make sure you say the sound, and not the alphabetical name of the letter. Frequently very successful. [Compare first letter cueing, semantic cueing and silent articulatory cueing.]
Phonemic Jargon: One of three clinically distinct subtypes of jargon aphasia. Jargon characterised by the frequent use of rhymes and alliterations. [Compare neologistic jargon and semantic jargon.]
Phonemic Paraphasia: A paraphasia where the mis-selection is due to phonemic confusion, that is to say, where the actual utterance bears a sound similarity to the intended utterance (e.g. "shark" for "sharp"). [Compare semantic paraphasia.]
PLE: See paraneoplastic limbic encephalitis.
Post-Traumatic Amnesia (PTA): An amnesia associated with a traumatic head injury. Most brain traumas, and especially concussions and seizures are accompanied by a period of unconsciousness, recovery from which can take time. This is followed by a degree of confusion, especially as to personal identity, date, and the circumstances leading to the hospitalisation.
Praxis: The capacity for voluntary bodily movement. [Caution: when considering willed movement, it is worth remembering that nobody has yet located the will which does the willing!]
Premorbid: The period before the onset of the disease or injury in question.
Progressive Disorder: A disorder which takes time to develop, but where the deterioration is largely irreversible. Eg: Alzheimer's disease.
Prosopagnosia: [Greek prosopon = "face".] An agnosia specifically for familiar faces, despite generally preserved visual perception. First formally named by Bodamer (1947) [timeline].
Pseudobulbar Palsy: Facial and/or pharyngeal palsy resulting from damage to upper motor neurons in the corresponding sectors of the primary motor cortex. [Compare bulbar palsy.]
Psychogenic Disorder: A mental (i.e. psychiatric) rather than physical (i.e. bodily) disorder. Compare and contrast organic disorders.
Qualia: [Single quale.] "The properties of sensory experiences" (The Free Dictionary, 2004). The hotness of something hot, or the redness of something red, as experienced by the conscious mind.
Reductionism: The doctrine that things can be best explained by analysing them into their component parts.
Reduplicative Paramnesia: A clinical sign. Specifically, a form of confusion as to location which results in memories of familiar places being incorrectly merged or relocated (ie. "duplicated"). McCarthy and Warrington (1990) offer the example of patients who think that their hospital room is some sort of an extension to their original dwelling place. Stuss and Benson (1986) review the literature here and conclude that the right parietal and frontal lobes are regularly implicated in patients displaying this behaviour.
Representation, First Order: A state of mental activation in which a number of concept nodes are (a) activated, and (b) allocated specific linguistic roles in order to support a proposition [Psycholinguistics Glossary] of the form <[MAIN CLAUSE] subject - mental verb - [SUBORDINATE CLAUSE AS OBJECT] subordinator - embedded subject - complementiser - complement> [for definitions of these grammatical terms, see Psycholinguistics Glossary]. Example: "Tom knows that snow is white". [Now compare representation, second order.]
Representation, Second Order: [See firstly representation, first order.] A state of mental activation in which additional concept nodes are used to expand the propositional complexity of the ongoing thought process by subordinating what is already a first order representation. The resulting form is <[MAIN CLAUSE] subject - mental verb - [FIRST SUBORDINATE CLAUSE AS OBJECT] subordinator - first embedded subject - [SECOND SUBORDINATE CLAUSE AS OBJECT] subordinator - second embedded subject - complementiser - complement>. It follows that second order representations will therefore always be one mental verb longer than first order ones [Example: "Sally accepts that Tom knows that snow is white"], and you can, of course, substitute any one of the full range of mental verbs at any point, according to the precise truth you wish to convey [Example: "Sally doubts that Tom understands that snow is white"]. [Now compare representation, third order.]
Representation, Third Order: [See firstly representation, second order.] A state of mental activation in which additional concept nodes are used to expand the propositional complexity of the ongoing thought process by subordinating what is already a second order representation. It follows that third order representations will therefore always be one mental verb longer than second order ones [Example: "Peter believes that Sally accepts that Tom knows that snow is white"].
Resection: "Surgical removal of a portion of any part of the body" (Oxford Dictionary for Nurses).
Retrograde Amnesia: An amnesia which acts backwards in time from the moment of insult. It is therefore characterised by a difficulty accessing aspects of personal past life such as personal identity and episodic memories. Past semantic knowledge, on the other hand, is largely spared. [Compare anterograde amnesia.]
RHS: See right hemisphere syndrome.
Right Hemisphere Syndrome (RHS): A pattern of disabilities typically associated with a right-hemisphere lesion in right handers. Such lesions, of course, damage the non-dominant hemisphere. There are many typical clinical signs, but the overall effect is that linguistic skills are retained (because the dominant hemisphere is intact) and yet communicative competence is poor. The damage, in other words, is to higher functional areas such as semantics [Memory Glossary] and pragmatics [Psycholinguistics Glossary]. Language remains syntactically correct but complexity, richness, metaphor, figurativeness, and abstractness suffer. It is frequently difficult to distinguish the important from the irrelevant. Things are taken too literally. In addition, prosodic comprehension and production is lacking. [For more detail, see Myers and Mackisack (1990).]
Sarcoma: A cancer of connective tissue, including muscle, fat, bone, cartilage, and blood. [Compare carcinoma.]
Second Order Representation: See representation, second order.
Selective Amnesia: (Or hysterical amnesia.) A psychogenic amnesia directed at a particular experience or set of experiences, which are sufficiently ego-threatening (shock, fear, etc) to warrant being kept from consciousness by repression or other psychodynamic mechanism.
Semantic Anomia: One of the nine clinically distinct subtypes of anomia (1) recognised by Benson (1979).
Semantic Cueing: A type of cueing. Involves giving clues as to the meaning and/or use of the target word in the hope that this will help the patient access the lost speech output patterns (e.g. "You cook with it ....."). Frequently very successful. [Compare first letter cueing, phonemic cueing, and silent articulatory cueing.]
Semantic Jargon: One of three clinically distinct subtypes of jargon aphasia. Jargon characterised by the frequent use of synonyms and near synonyms. [Compare neologistic jargon and phonemic jargon.]
Semantic Lexicon: The semantic element of the lexicon (1). A web of concept associations and categories capable of giving meaning to an individual concept. The semantic lexicon, together with the associated word-form lexicons (2), constitute the mind's mental word store in its entirety. There is a mass of evidence, however, that they are not co-located in the brain, and when a word form cannot be associated with its semantic referent what we end up with, of course, is an anomia (1). [There is an expanded definition of this term in our psycholinguistics glossary.]
Semantic Paralexia: A paralexia where the mis-selection is due to some type of semantic confusion, that is to say, where the actual utterance bears some conceptual relationship to the intended utterance (e.g."bread" for "food"). A frequent clinical indicator of deep dyslexia. For a fuller list of typical errors of this type, see Coltheart, Patterson, and Marshall (1980).
Semantic Paraphasia: A paraphasia where the mis-selection is due to some type of semantic confusion, that is to say, where the actual utterance bears some conceptual relationship to the intended utterance (e.g."bread" for "food"). [Compare phonemic paraphasia.]
Senile Dementia: [See firstly dementia.] A general descriptor for forgetfulness and similar symptoms in the aged, rather than a disease process in its own right. May, upon further investigation, turn out to be Alzheimer's disease or multiple-infarct dementia, or just normal wear and tear.
Sign: An outwardly visible correlate of a disease or injury. [Compare symptom.]
Silent Articulatory Cueing: A type of cueing. Involves silently miming the tongue and lip movements of the target word, perhaps with an element of exaggeration, in the hope that this will help the patient access the lost speech output patterns (e.g. "Watch my lips .....<mime>"). [Compare first letter cueing, phonemic cueing and semantic cueing.]
Small Vessel Disease: Blockage, deterioration, and leaking of blood vessels too small to be operated on. If within the brain, then a serious form of cerebro-vascular disease. [More]
Spastic Dysarthria: One of the six clinically distinct subtypes of dysarthria recognised by Darley, Aronson, and Brown (1975). [There is a longer discussion of the subtypes of dysarthria in Section 6.8 of our e-paper on "Speech Errors, Speech Production Models, and Speech Pathology".]
Spasticity: State of rigidity and spasm of the skeletal muscles. Occurs as a result of damage to the pathways inhibiting muscular contraction. [Compare paresis.]
Spontaneous Recovery: Literally, improvements which "just happen". The term is used typically to describe the often quite considerable improvements in CVA patients in the weeks-to-months following the insult. These occur without therapy, and are usually attributed to two major factors. Firstly, there are naturally occurring organic repair processes (such as swellings going down, etc.), and secondly there may be some "recruitment" of undamaged neural tissue to take over the functions of that which has been lost. The effectiveness of therapy during a period of spontaneous recovery is, not surprisingly, difficult to assess.
Stereognosis: Knowing and being able to recognise the solid form of objects by tactile inspection. This ability is heavily lateralised so that the right hand loses this ability with a left-hemisphere lesion (and vice versa).
Stroke: The everyday term for cerebro-vascular accident or transient ischaemic attack.
Surface Dyslexia: A subtype of acquired dyslexia characterised primarily by difficulties at the "whole word" visual word recognition stage, when reading aloud [compare deep dyslexia]. Typical problems are (a) "regularisation" of irregular words (e.g. pronouncing "come" to rhyme with "home"), and (b) "visual frequency effects" (e.g. reading "region" for "reign").
Symptom: An outwardly invisible correlate of a disease or injury, and one therefore which can only be detected by listening to the subjective report of the patient. [Compare sign.]
Syndrome: A symptom complex, that is to say, a collection of signs and symptoms which for some reason seem to "go together", and which characterise a particular disorder.
Telegraphic Speech: With agrammatism, patients often omit the function words [glossary] while retaining the content words [glossary]. Properly controlled, this enforced brevity can markedly reduce word count without reducing intelligibility, hence the metaphoric link with the style we adopt when sending telegrams. A frequent sign of Broca's aphasia.
Thalamic Aphasia: A fluent aphasia characterised by severe jargon. Believed by workers such as Crosson (1985) to be due to impaired ability of the thalamus to organise internal and external speech output monitoring.
THI: See traumatic head injury.
Thrombosis: The state of having a clot or blockage (the thrombus) attached to, and restricting flow through, a blood vessel.
Thrombus: See thrombosis.
TIA: See transient ischaemic attack.
Tourette's Syndrome: A tic disorder named after the French neurologist Gilles de la Tourette (1857-1904) [more history], and characterised by involuntary motor spasms and vocalisations, either verbal or non-verbal [more].
Transcoding Model: See the detailed definition in our psycholinguistics glossary.
Transcortical Motor Aphasia: A non-fluent aphasia similar to Broca's aphasia. Repetition is relatively unimpaired, but there is little spontaneous speech, more severe dyspraxia, and frequent echolalia. [See also Lichtheim's house.]
Transcortical Sensory Aphasia: Similar to Wernicke's aphasia, but with unimpaired word repetition. [See also Lichtheim's house.]
Transient Epileptic Amnesia: A short-term amnesia relating to the moments of an epileptic seizure.
Transient Global Amnesia: A short-term amnesic state (1 - 24 hours), possibly due to transient ischaemia.
Transient Ischaemic Attack (TIA): Short period of ischaemia, followed by more or less complete recovery within 24 hours [compare cerebro-vascular accident].
Trauma (1): [Greek = wound.] Alternative term for physical injury, as in traumatic head injury. [Contrast trauma (2).]
Trauma (2): [Greek = wound.] Alternative term for mental injury, as in cases of selective amnesias brought about by psychologically shocking or hurtful experiences such as combat where there is no direct physical injury. One of Freud's main contributions to our understanding of the unconscious mind was his insistence that we seek out the traumas we had somehow locked away within ourselves. [Contrast trauma (1).]
Traumatic Head Injury (THI): Any impact-related head injury. [See and compare closed head injury and penetrating head injury.]
Tumour: A focal growth; a swelling. [See also cancer, benign, and malignant.]
Upper Motor Neuron: See our e-handout on "The Pyramidal and Extrapyramidal Motor Systems".
Visual Agnosia: An inability to recognise visually presented objects.
Wernicke's Aphasia: A fluent aphasia characterised by auditory comprehension loss not accompanied by sensory deafness. First described by Wernicke (1874). There is defective repetition of both words and sentences. Speech can remain fluent but its content becomes paraphasic due to loss of internal correction (ie. the patient does not understand what s/he is saying any more than s/he understands what others are saying). The lesion is classically located in Wernicke's area. [See also Lichtheim's house.]
Wernicke's Area: Usually identified as the first (some prefer the designation superior) temporal convolution of the left hemisphere, and the site of a classic Wernicke's aphasia. Centred on Brodmann's Area 22 [to see where this is on the cortical map, click here, and to see Wernicke's own diagram, click here].
Wernicke-Korsakow Syndrome (WKS): A degenerative condition often resulting from chronic alcoholism.
WKS: See Wernicke-Korsakow syndrome.
Word Finding Difficulty: A self-explanatory synonym for anomia (1).
Word Production Anomia: One of the nine clinically distinct subtypes of anomia (1) recognised by Benson (1979). An anomia in which the naming defect is resolvable upon phonemic cueing. [Compare word selection anomia.]
Word Selection Anomia: One of the nine clinically distinct subtypes of anomia (1) recognised by Benson (1979). An anomia in which the naming defect is not resolvable upon cueing. Gnosis is intact (because patients can immediately point to the object in question if told its name), and conversational speech is otherwise fluent and effortless. [Compare word production anomia.]