Cognitive processes studies

Hemispheric Specialisation

Also called hemispheric lateralisation, hemispheric dominance, the idea that each hemisphere of the brain has specialised functions or exerts greater control over a particular function

Spatial Neglect

Also known as neglect syndrome, in which the person affected systematically ignores stimuli on one side (either left or right) of their body as a result of damage to one of the cerebral hemispheres

What is Broca's aphasia?

Broca's aphasia is an impairment in the ability to produce articulate speech, caused by damage to Broca's area

what studies led to the discovery of Broca's area?

Broca's study of Tan

People with spatial neglect cannot turn left even though they are told left exists. Why?

The person intellectually understands left exists but instinctively to them, left doesn't exist

Why are split brain operations undertaken?

To prevent the spread of severe epileptic seizures from 1 side of the brain to the other

Since broca's aphasia does not impair motor functions...

ability to vocalise is not lostbut ability to translate info into speech patterns and express meaning is compromised

Spatial neglect mainly relates to

visual stimuli

Most sufferers of spatial neglect have

anosognosia but some have anosodiaphoria

Split brains are connected

at a subsortical (deeper level)

anosognosia

blissfully unaware of their impairment

Those with spatial neglect not only have a deficit limited to stimuli in surrounding environment,

but also in memory (may only remember one side of a memory)

Split brain operations are

invasive

what is 'location of function'

linking the location of the brain with specific function

Damage to Broca's area does not impair...

motor instructions for vocalising words because some people still speak well rehersed phrases, recite poems, sing and swear (usually spontaneously) with ease and require little mental effort

Wernicke's aphaisa sufferers

often have anosognosia

Anomia

partial or complete loss of ability to recall names

Damage to neural connection between Wernicke's area and Broca's area may cause

person to be unable to repeat what you say to them

In most cases of spatial neglect, there is damage to:

posterior region of their right parietal lobe

The split brain operation is also called

Commisurotomy

anosodiaphoria

Know they have a problem but seem unconcerned about it

Broca's aphasia is also referred to as ___ because...

- Expressive aphasia - because person has difficulty expressing themselves

Right hemisphere specialisation

- Holistic specialisation - Non-Verbal, non language functions - Recognises faces, non language sounds (music and melodies), pictures, complex visual/geometric patterns - Daydream, creativity, fantasy - Produces and/or appreciates artwork and music - detects and expresses, non-verbal emotions - performs spatial tasks (such as arrange blocks to match pattern, jigsaw, draw, judge distance and direction, mental shape rotation, visualising)

Left hemisphere specialisations

- Sequential processing - Verbal and language functions such as reading, writing, speaking, understanding language - analytical functions such as logic and reasoning - speech production - judges and experiences time as a series of units - planning, organising - mathematical ability, scientific data - Self recognition - Rhythm and pitch - process sensations and control movement on Left side of body

Aphasia

- The impairment of language caused by damage to the left hemisphere of the brain in the regions called Broca's area (impairing speech production) or Wernicke's area (impairing understanding of language) - It can affect talking, reading, writing and understanding others - DOES NOT affect intelligence

Damage to association areas surrounding either Broca's or Wernicke's area

- This would isolate the areas from the rest of the brain - thus the person would be unable to speak - may even appear to not understand what is being said to them

Generalising findings of case studies is difficult because:

- brains are unique and the precise location of Broca's and Wernicke's area varies between people - Brain scans reveal that many areas of the brain are associated with langauge use and this pattern of brain activation changes depending on the person and how the language is being used at any given moment - aphasia results from brain damage; extent of brain damage varies between people thus extent of effects on language will be different in different people

Contribution of spatial neglect studies

- can be a result of brain damage - location and extent of damage likely to influence degree of neglect (mild - severe) - has serious implications for consciousness (limits perceptions, thoughts, behaviours and feelings)

What symptoms did Tan experience

- lack of speaking ability yet intellectually normal - was developing paralysis of right arm and right leg

Limitations of generalising split brains

- most performed on males and right handed - in general, R handed have main language centres in L hemisphere WHILE L handed may have main language centres in either L or R hemisphere - All suffered from severe epilepsy and thus may affect performance - All on long term medication which may have had side effects and may have caused exaggerated results

Broca's area responsible for...

- production of articulate speech - movement of the muscles required for speech (lips, tongue, mouth, throat, neck muscles) - meaning of words, sentence structure, word type (noun, verb, adj) - analysing grammatical structure

Wernicke's aphasia is also referred to as ___ but...

- receptive aphasia - this is misleading because the the difficulties experienced is not just limited to understanding language

Characteristics of Broca's aphasia

- slow, laboured (involves great effort) fragmented speech that is non-fluent (pauses between words, especially those that are not well rehearsed) hence speech tends to be broken with some managing only a couple of words at a time - partial or complete loss of ability to recall names (anomia) [person may have trouble finding and naming the right words] - articulation difficulties and words may be mispronounced - speech lacks grammar (agrammatism); doesnt follow grammatical rules - lacks syntax [speech tends to contain nouns and verbs but lacks others 'drive car, give money'] - difficulty in writing - mild comprehension problems: comprehension can sometimes be impaired - usually related to complex sentences 'geelong was beaten by richmond' confused with 'geelong beat richmond'

Characteristics of Wernicke's aphasia

- speech fluent - anomia - nonsense words used (meaningless words, nonsense syllables, mispronounced words) - difficulty understanding both written and spoken language - difficulty producing both written and spoken language that makes sense to others

Treatment for Broca's aphasia

- therapy focussed on relearning the rules (syntax) of language - other brain areas took cover task of communicating language (plasticity)

Contribution of split brain studies

...

What is Wernicke's aphasia

An impairment in the ability to understand language and formulate coherent, meaningful speech, caused by damage to Wernicke's area

Broca's aphasia sufferers

Are usually conscious of their impairment

Split Brain operation

Brain surgery involving the severing of an area of the corpus callosum to interrupt the flow of info between the 2 cerebral hemispheres

agrammatism

speech lacking grammar