Assocation cortices and complex brain functions Flashcards
Outline the hierarchal organisation of the brain and give an exmapled
HIGHEST ORDER: Association cortex
- Unimodal association areas
- Multimodal association areas
Secondary sensory cortex
Primary sensory cortex
Thalamic relay nuclei
LOWEST ORDER: Receptors
e.g. The visual system
There are three main multimodal association areas, what are they?
- Posterior association area- perception, language
- Temporal association area- higher order visual processing, emotion, memory
- Prefrontal association area- personality changes, executive functions, good anxiety
Define the following 4 terms:
- Agnosia
- Prosopagnosia
- Visual agnosia
- Anosognosia
Agnosia: inability to interpret sensations and hence to recognize things. Apperceptive agnosia is a failure in recognition that is due to a failure of perception. In contrast, associative agnosia is a type of agnosia where perception occurs but recognition still does not occur.
Prosopagnosia- inability to recognize faces.
`Visual agnosia- a condition in which a person can see but cannot recognize or interpret visual information, due to a disorder in the parietal lobes.
Anosognosia- a deficit of self-awareness, a condition in which a person with some disability seems unaware of its existence.
How is information relayed to multimodal association areas
What is the difference between serial and parallel processing?
What is different about information processing in a motor system?
Information converged from unimodal to multimodal areas
Serial processing is hierarchial information processing, from low to high. Parallel processing from different cortical areas at the same hierarchial level
SEQUENCE OF INFORMATION PROCESSING IS REVERSED IN MOTOR SYSTEM
What happens in motor planning?
How do complex actions arise?
General outline of behaviour–> concrete motor responses
Individual neurons in the frontal cortex fire for a range of related behaviours. Movements and complex actions arise from patterns of firing of large networks of neurons
The premotor cortex generates motor programs and the neurons are active during preparation of movement
In the motor cortex neurons mainly fire to produce movements in particular directions and around specific joints
Outline the process of language
There are specialised language areas in the brain such as…
Language comes into brain through visual and auditory systems
Motor system: Produces speech, writing
Processing between sensory and motor systems; Essence of language
Motor area responsible for motor control of mouth and lips
Broca’s area (anterior side of centra gyrus, under motor cortex)
Auditory cortex
Wernickes area (inferior to lateral gyrus, post sentral gyrus, next to Angular gyrus)
What is the WADA procedure used for?
Used to determine hemisphere dominant for speech
!Asymmetrical language processing
What is aphasia?
partial or complete loss of language abilities following brain damage, often without the loss of cognitive faculties or the ability to move the muscles used in speech
What do split brain studies show?
Asymmetrical language processing
The hemispheres may retain some communication via the brain stem or smaller commissures (if they aren’t also severed), but most of the communication between the cerebral hemispheres is lost. The two hemispheres can initiate conflicting behaviours, e.g. alien hand syndrome.
Demonstrating language comprehension in the right hemisphere: Patient sees nothing as words are on the left side and the left hemisphere which usually controls speech didnt see the word, and the right hemisphere which saw the word, cannot speak. However, the left hand, which is controlled by the right hemisphere can pick out the object corresponding to the word
How does Wernickes aphasia present?
Fluent speech
Poor comprehension
Words form coherant speech with no meaning. SPEECH DOESNT MAKE SENSE
How does aphasia in bilinguals present?
Depends on order learnt, fluency and use
How does Brocas, motor, non-fluent aphasia present?
Telographic repitition of known words
State 4 types of aphasia
- Brocas, motor, non-fluent aphasia
- Wernickes aphasia
- Bilingual aphasia
- Sign language and aphasia
