Language and the brain Flashcards
Aphasia
An umbrella term: meaning disruption to, or loss of, language function.
Commonly seen in following brain damage or disease (40% of stroke victims)
Franz Joseph Gall
Some of his friends had protruding eyeballs, reasoned that this was because the brain behind the eyes had grown to accommodate a superior language faculty.
First idea that language was in the frontal lobes.
Broca study
Got a patient with a serious leg infection, right hemiparesis and loss of speech (known as Tan because thats the only word he spoke). After his death; found that he had damage to LEFT POSTERIOR FRONTAL GYRUS (brocades area).
Broca named the condition APHEMIA (disruption of voluntary speech production).
Broac´s area
Left posterior frontal gyrus
Wernicke study
Described two patient with different type of language disorder.
They had fluent speech, but incomprehensible, and difficulty understanding spoken language. thought it was because this region involved in auditory memory of words.
Wernickes area
Posterior superior temporal gyrus on the left hemisphere.
Broca´s apahsia
impairment is a matter of degree, but the core feature is difficulty in producing coherent speech.
Expressive or non-fluent aphasia
Most can speak a little, but have trouble finding the words they want to use.
reading might be unaffected.
Have insight into their own language deficit.
Telegraphic speech
Two word speech, that makes sense e.g. “get milk”.
Non-fluent agrammatic speech associated with Broca´s aphasia.
Wernicke´s aphasia
Related to comprehension and meaningful output. They use nonword or made-up words (neologisms).
Lack insight to their disease, talk nonsense without realizing it and unaware that others can’t understand them.
Paraphasias
words that are semantically related to the desired word, but nevertheless inappropriate (wernickes aphasia).
Lichtheim model
Connectionist model of language (inspired by Wernicke and Broca) to try to explain various aphasias.
Connectionist –> Different brain centers are interconnected and that impaired language function may result from damage to either one of the centers.
Believed that Broca and Wernicke´s area formed two points of a triangle, where the third point represented a “concept center”, where word meanings were stored and auditory comprehension occurred. This points were interconnected, so damage to either of them would induce a form of aphasia.
Arcuate fasciculus
fibre bundle connecting Broca and Wernicke area.
Wernicke first suggested that wernicke area could be anatomically linked to brooks area.
hemiparesis
Partial or complete loss of movement in one side of the body.
Conduction aphasia
characterized by intact auditory comprehension, fluent (yet paraphasic) speech production, but poor speech repetition
Concept center (Lichtheim model)
were word meanings were stored and auditory comprehension occurred. The exact location was unclear, but himself argued that that concepts were distributed widely throughout the cortex.
Recent interpretation (Geschwind) localized it to the left inferior parietal lobe encompassing the angular gyrus.
Motor aphasia
similar to Broca´s, but spontaneous speech is absent. Another feature is Echolalia.
Damage: pathway between SUPPLEMENTARY MOTOR AREA and BROCA´S AREA can bring about this disorder
Echolalia
Repeat word and phrases they hear.
Sensory transcortical aphasia
Similar to Wernicke, but repetition is intact.
Might also have Echolalia
Global aphasia
Both Wernicke and Broca
Problems with connectionist models
- A lack of symptom specificity in aphasia
- Failure to appreciate the true complexities of requisite language processes in the brain
- Poor correspondence with recent neuroanatomical observations -> it is now known that damage to Broca´s area doesn’t always lead to Broca´s aphasia and the same is for Wernickes.
Psycholinguistic
The study of the structure of language in normal people, rather than the study of language dysfunction in neurological patient
Phonology
Basic speech sounds (ba, pa, ta are all phonemes)
Semantics
Study of meaning in language.
Wernicke aphasia patient produce speech that is correctly structured, but difficult to understand. Such aphasia would have to do with deficit in semantic processing, rather than syntactic mechanisms.
Syntax
grammer, how words are strung together through implicit rules
Pragmatics
How context contributes to meaning
Anomia
Problem in naming objects. some form of anomina is common in both Broca´s and Wernickes.
JBR case study
Anomic patient
Widespread temporal lobe damage > impaired at naming living things, but not inanimate things (umbrella).
He had also problems with understanding the spoken names of items that he couldn’t name himself.
MD case study
Anomic patient
Deficit in naming animate object, but could sort pictures of animate and inanimate items well, and could also discriminate heard and read words from each category.
JBR might have incurred loss of semantic knowledge of specific categories, while MD had retained the semantic representations but his access to it from picture or actual objects were impaired.
JCU case study
Anomic patient
Had widespread generalized anomia for objects from various categories, yet could name the items correctly if given the initial phoneme (sound) of the word. He was also prone to naming semantically related items if given the wrong phoneme (e.g name a tiger and given the phoneme L, he incorrectly said LION
Neologistic jargonaphasia
Can be seen in Wernickes aphasia.
Create new words phonologically similar words for items they are not familiar with i.e. pheharst instead of perhaps.
They might, however, have semantic knowledge of the unnamable times.
PET scan in examining Brocas apahasia
When PET is used to examine “resting” brain function, patient with non-fluent (Broca) aphasia show under activation in left frontal regions, while patients with fluent aphasia (Wernicke) show under activation in more posterior regions.
Neuroimaging of spoken word perception
It has shed new light on classical aphasia based-models, suggesting that THE LEFT POSTERIOR SUPERIOR TEMPORAL GYRUS (Wernickes) is functionally heterogenous
Neuroimaging of reading single words
left posterior inferior frontal gyrus (Broca´s) is activated when reading regular or irregular words.
Language and laterality
Reasonable to conclude that language is mediated by a series of interconnected regions in the LEFT hemisphere, this pattern is found in almost all right-handers, and the majority of left-handers.
It is not exclusively in the left hemisphere, activity has also been found in the same regions of the right hemisphere, but to a lesser extent.
There is evidence that certain aspects of language are managed, perhaps predominantly, by the right hemisphere such as the processing of EMOTIONAL ASPECTS of language. example: individual with right hemisphere damage may speak in a monotone, despite understanding the emotional aspects of what they are saying. This can be found in the equivalent location to Broca´s on the left. > more posterior right-sided damage (roughly equivalent to Wernickes on the left) can lead to difficulties in interpreting emotional tone.
Aprosodic speech
free of emotional intonation, or monotone
