chapter 16

acquired dyslexias

acquired dyslexias

Dyslexias caused by brain damage in people previously capable of reading

Agraphia

A specific inability to write; one that does not result from general visual, motor, or intellectual deficits.

Alexia

A specific inability to read; one that does not result from general visual, motor, or intellectual deficits.

Angular gyrus

The gyrus of the posterior cortex at the boundary between the temporal and parietal lobes. According to the Wernicke-Geschwind model the left hemisphere angular gyrus plays a role in reading.

Aphasia

A brain damage–produced deficit in the ability to produce or comprehend language.

Arcuate fasciculus

The major neural pathway between Broca’s area and Wernicke’s area.

Broca’s aphasia

A hypothetical disorder of speech production with no associated deficits in language comprehension.

Broca’s area

The area of the inferior prefrontal cortex of the left hemisphere hypothesized by Broca to be the center of speech production.

chimeric figures test

A test of visual completion in split-brain subjects that uses pictures composed of the left and right halves of two different faces.

Commissurotomy

Surgical severing of the cerebral commissures.

Conduction aphasia

A hypothetical aphasia that is thought to result from damage to the arcuate fasciculus—the pathway between Broca’s and Wernicke’s areas.

cross-cuing

Communication between hemispheres that have been separated by commissurotomy via an external route.

deep dyslexia

A reading disorder in which the phonetic procedure is disrupted while the lexical procedure is not.

developmental dyslexias

Dyslexias that become apparent when a child is learning to read.

Dextrals

right-handers

Dominant hemisphere

A term used in the past to refer to the left hemisphere, based on the incorrect assumption that the left hemisphere is dominant in all complex behavioral and cognitive activities.

Dyslexia

A reading disorder that does not result from general visual, motor, or intellectual deficits.

Expressive

Pertaining to the generation of language; that is, pertaining to writing or talking.

frontal operculum

The area of prefrontal cortex that in the left hemisphere is the location of Broca’s area.

Global aphasia

Severe disruption of all language-related abilities.

grammatical analysis

Analysis of the structure of language.

helping-hand phenomenon

The redirection of one hand of a split-brain patient by the other hand.

hemispherectomy

The removal of one cerebral hemisphere.

Heschl’s gyrus

The temporal lobe gyrus that is the location of primary auditory cortex.

Lateralization of function

The unequal representation of various psychological functions in the two hemispheres of the brain; cerebral hemispheres are specializrd for different functions

lexical procedure

A procedure for reading aloud that is based on specific stored information acquired about written words.

Minor hemisphere

A term used in the past to refer to the right hemisphere, based on the incorrect assumption that the left hemisphere is dominant.

motor theory of speech perception

The theory that the perception of speech involves activation of the same areas of the brain that are involved in the production of speech.

phoneme

The smallest unit of sound that distinguishes among various words in a language.

phonetic procedure

A procedure for reading aloud that involves the recognition of letters and the application of a language’s rules of pronunciation.

phonological analysis

Analysis of the sound of language

planum temporale

An area of temporal lobe cortex that lies in the posterior region of the lateral fissure and, in the left hemisphere, roughly corresponds to Wernicke’s area.

Receptive

Pertaining to the comprehension of language and speech.

scotoma

An area of blindness produced by damage to, or disruption of, an area of the visual system.

semantic analysis

Analysis of the meaning of language.

sinestrals

left-handers

split-brain patients

commissurotomized patients

surface dyslexia

A reading disorder in which the lexical procedure is disrupted while the phonetic procedure is not

visual completion

The completion or filling in of a scotoma by the brain.

Wernicke-Geschwind model

An influential model of cortical language localization in the left hemisphere.

Wernicke’s aphasia

A hypothetical disorder of language comprehension with no associated deficits in speech production.

Wernicke’s area

The area of the left temporal cortex hypothesized by Wernicke to be the center of language comprehension.

Paraphasia

substitute for a word by a sound, incorrect word, or captionN

neologism

an entirely novel, nonsense word

Nonfluent speech

talking with considerable effort, in short sentences, and without the usual melodic characteristic of conventional speech

Non-fluent aphasia

broca’s aphasia

fluent aphasia

wernicke’s aphasia