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Localisation of Function 2: Functional architecture (Cortical Networks…
Localisation of Function 2: Functional architecture
Cortical Networks
Primate brain is composed of about 10 to the 12 neurones with 10 to the 15 connections
Cerebral cortex contain
networked areas
-> process and exchange information
Networks are specific to modalities (e.g. auditory, motor etc.)
These areas communicate with each other
Different levels of the network represent the information at different levels of abstraction
E.g. what are the properties of a £5 note?
Prefrontal areas that represent rewards are activated when thinking about its value
One half of the thalamus in each hemisphere - different parts communicate with different parts of the neocortex
Olfactory system doesn't pass through the thalamus - very immediate and poignant information
The Cortex
3 general functional types of cortex
Primary Cortex
Initial level of cortical processing
Low level info (least abstract)
Specific to one modality
Unimodal cortex
Intermediate cortical processing & intermediate level info
Activity specific to one modality
Supramodal Cortex
High level processing, most abstract level
Activity NOT specific to one modality but to a type of info processing
Neurones fire in relation to an abstract property (preference for a certain reward) - not the physical parameters of the stimulus (e.g. edges, colours etc.)
Primary Visual Cortex
Retina projects to the LGN of the thalamus -> relays info to the PVC (first area to process visual information)
Different areas of the visual field are represented in discrete areas of the cortex
You can map positions that radiate in the direction of the visual stimuli (change in voltage in the brain)
Correspondence between voltage and what they are seeing
Primary Cortices
Orientation selectivity
Neurones fire in relation to the
orientation of a visual stimuli
Organised into orientation-specific 'columns'
Primary Auditory Cortex
Information is relayed to the MGN of the thalamus
Projects to the Primary Auditory Cortex in the superior temporal gyrus of the temporal lobe
Called the 'core'
Cells fire in relation to different auditory frequencies and are mapped
cochleotopically
Primary Motor Cortex
PMC sends info to the spinal cord
Primary cortical area because it is at the lowest point of the motor hierarchy
When neurones are stimulated, different muscle groups on the contralateral (opposite) side are activated
Can be used for prosthetics - brain can interface with technology and bypass the damaged area
Unimodal
Visual
Many visual areas outside the PVC - selective for visual stimuli
Distributed in the
occipital, temporal & parietal lobes
Dorsal stream = where
Ventral stream = what
Auditory
Several areas - core, belt & parable cortices
Motor
Outputs -> PMC & spine
Areas of MC are called
premotor areas
All in the frontal lobe
Subregions = dorsal, ventral & medial
Supramodal Cortex
Aka - association cortex
Very complex responses