Brain cortex and lateralisation
Anatomy – the cerebral cortex (outside of brain)
Gyri, sulci, fissures
The corpus callosum – fibre bundles that connected two hemispheres + small
commissures like the anterior and hippocampal commissures allow exchange
of information between hemispheres.
Corpus callosum gradually grows and thickens as myelin increases around
certain axons during childhood and adolescence
- Young children struggle comparing or integrating actions between left
and right hands.
- The corpus callosum matures a lot between age of 3 and 5 to facilitate
comparison of stimuli between the two hands.
Brodmann area (1909) – identified 52 distinct areas that are still in use – did
this by staining brain tissue and identified 52 different areas that stained in
different ways.
Primary visual cortex
- Vision (striate cortex)
BA 17 = primary visual cortex (V1)
BA 18 = secondary visual cortex (V2)
BA 19 = Visual association cortex (V3)
Each hemisphere of the brain gets input from the opposite half of the visual
world
The visual field is what is visible at any moment
Human vision
The left half of each retina connects to the left hemisphere; i.e. sees the right
visual field
The right half of each retina connects to the right hemisphere; i.e. sees the left
visual field
Half of the axons from each eye cross to the opposite side of the brain at the
optic chiasm
, Occipital cortex = primary visual and higher order visual areas + projections
into the parietal and temporal areas
Occipital lobe deals with early visual processes. While temporal and parietal
lobe are involved in higher order visual processes.
- V1 = cells respond to stimuli of different orientation, later on in the
visual processing stream cells respond to complex stimuli like faces
Damage to v1 = cortical blindness = patients can’t consciously see anything
Visual agnosias = what pathway = object recognition and prosopagnosia
Damage to where pathway – optic ataxia – loss of visually guided movement
control
Somatosensory processing
Touch (Somatosensation)
BA 1,2,3 = primary somatosensory cortex
BA 5 and 7 = somatosensory association cortices
Somatosensory cortex is located in the parietal
lobe behind the central sulcus and has a
complete presentation of the body
Lateralization: left primary somatosensory cortex
receives information from right body side while
right somatosensory cortex receives information
from left body side
Auditory processing – hearing
BA 41 = Primary auditory cortex
BA 42 = auditory association cortex
Primary auditory cortex is located in the temporal lobe and has a ionotropic
organisation
Anatomy – the cerebral cortex (outside of brain)
Gyri, sulci, fissures
The corpus callosum – fibre bundles that connected two hemispheres + small
commissures like the anterior and hippocampal commissures allow exchange
of information between hemispheres.
Corpus callosum gradually grows and thickens as myelin increases around
certain axons during childhood and adolescence
- Young children struggle comparing or integrating actions between left
and right hands.
- The corpus callosum matures a lot between age of 3 and 5 to facilitate
comparison of stimuli between the two hands.
Brodmann area (1909) – identified 52 distinct areas that are still in use – did
this by staining brain tissue and identified 52 different areas that stained in
different ways.
Primary visual cortex
- Vision (striate cortex)
BA 17 = primary visual cortex (V1)
BA 18 = secondary visual cortex (V2)
BA 19 = Visual association cortex (V3)
Each hemisphere of the brain gets input from the opposite half of the visual
world
The visual field is what is visible at any moment
Human vision
The left half of each retina connects to the left hemisphere; i.e. sees the right
visual field
The right half of each retina connects to the right hemisphere; i.e. sees the left
visual field
Half of the axons from each eye cross to the opposite side of the brain at the
optic chiasm
, Occipital cortex = primary visual and higher order visual areas + projections
into the parietal and temporal areas
Occipital lobe deals with early visual processes. While temporal and parietal
lobe are involved in higher order visual processes.
- V1 = cells respond to stimuli of different orientation, later on in the
visual processing stream cells respond to complex stimuli like faces
Damage to v1 = cortical blindness = patients can’t consciously see anything
Visual agnosias = what pathway = object recognition and prosopagnosia
Damage to where pathway – optic ataxia – loss of visually guided movement
control
Somatosensory processing
Touch (Somatosensation)
BA 1,2,3 = primary somatosensory cortex
BA 5 and 7 = somatosensory association cortices
Somatosensory cortex is located in the parietal
lobe behind the central sulcus and has a
complete presentation of the body
Lateralization: left primary somatosensory cortex
receives information from right body side while
right somatosensory cortex receives information
from left body side
Auditory processing – hearing
BA 41 = Primary auditory cortex
BA 42 = auditory association cortex
Primary auditory cortex is located in the temporal lobe and has a ionotropic
organisation
