Chapter 11

Glossary

Alexia/dyslexia Both refer to problems in reading written language. Alexia always refers to acquired difficulties in reading, while dyslexia is used to refer to developmental difficulties in reading. However some specific acquired reading problems – e.g. deep versus surface dyslexia – are used to refer to particular profiles of acquired reading problems.

Aphasia An acquired language disorder, which primarily affects the comprehension of spoken language (a receptive aphasia), or the production of spoken language (expressive aphasia). In global aphasia, both speech production and perception are compromised.

Boston Aphasia Classification System (BACS) A systematic classification of aphasic profiles which can be used to identify aphasia and to predict what profiles of damage a patients might be expected to show when assessing their damage. The Boston Classification System builds on the models of aphasia which were developed by Broca, Wernicke and Lichtheim. Implicit in this approach is the concept that language can be localised in the human brain, and that different profiles of language deficits are related to distinctly different patterns of brain damage.

Dementia A persistent impairment in intellectual function due to brain dysfunction, which commonly is associated with a progressive loss of function. It is mainly a disease of ageing, being more common in more elderly populations. Dementias can be relatively focal in their effects (e.g. semantic dementia) or more widespread and ‘global’ in their effects (e.g. Alzheimer’s disease). Some dementias primarily affect subcortical regions (e.g. Parkinson’s disease) and other have a more cortical effect (e.g. Pick’s disease).

Gyrus The surface of the brain is formed by the cerebral cortex, and this has its surface area greatly increased by being thrown into folds. A gyrus is the outer surface of one of these folds, and a sulcus is formed when in the depths of a fold. If the fold in the cortex is very deep it is called a fissure, like the lateral fissure which separates the temporal lobe from the frontal lobe.

Lesion Refers to tissue damage – in the brain this can be a result of a stroke, a tumour, an infectious disease, the effects of a toxin, a direct injury or a progressive disease (a dementia).

Neologisms Non-words which can be used by some neuropsychological patients in place of real words. The patients frequently do not know that they are not using real words. More widely, neologisms are used to refer to new words which are making their way into wider, more commonplace language use.

Stroke Refers to brain damage which occurs as a result of cardiovascular issues. The brain is an energy intensive organ, using around 20 percent of the available oxygen circulating in the blood supply. Disruption to blood supply causes brain damage to occur very quickly. The damage can occur due to a blockage in a blood vessel (an ischaemic stroke) or due to a blood vessel rupturing (haemorragic stroke). Strokes are associated with sudden onsets of symptoms of brain damage, and the symptoms can reduce in severity as time passes.

Summary

When we discuss language in the brain, we are discussing a wide range of representations and processes across perceptual, motoric, conceptual and syntactic levels. Language use incorporates both linguistic and non-linguistic processes, and it can be disturbed and disrupted in a wide variety of ways. Despite Henry Head’s distaste for ‘diagram-makers’ (Head 1926), considerable developments have been made by using cognitive models to reflect both on the different ways that acquired brain damage can affect language, and also how language is processed in the normal, healthy brain. Many aspects of the Kussmaul-Wernicke-Lichtheim model have subsequently been supported by functional imaging studies, including a dissociation between speech motor control, speech perception centres, and the wider conceptual-semantic system. In the distinction between anterior cortical temporal lobe areas which support the processing of intelligibility in speech, and posterior cortical temporal lobe areas which are important in repetition, there is some support for the concept that the phonological input lexicon may be distinct from the phonological input lexicon. When the field is extended to include reading, we can see both reading specific profiles (e.g. in the visual work form area) and activations common to reading and speech comprehension (e.g. in the anterior temporal lobe, STS and fusiform gyrus). Finally, developmental disorders of language reveal the potential impact of brain connectivity on reading development, and contributions of syntactic deficits, verbal working memory and motor skills to specific language impairments. We can see a potential role for auditory processing in stuttering, and a problem of the social use of language in autism.