Cerebral Cortex Flashcards
pyramidal neurons
role and neurotransmitter
primary excitatory cells in cortex
glutamate
small and medium pyramidal cells
project to areas of ipsilateral cortex
large and giant pyramidal cells
project to ipsilateral and contralateral cortex
subcortical areas, brainstem and spinal cord
non-pyramidal neurons role and neurotransmitter
mostly inhibitory
GABA
layer III of the cortex
contains medium pyramidal cells whose axons project to the ipsilateral cortex
layer IV of the cortex
major input layer
receives input form thalamus
layer V of the cortex
major output layer
contains medium, large and giant pyramidal cells
how many layers does the cortex have
6
astrocyte glutamine recycling
Glutamate is reabsorbed by the astrocyte, converted to glutamine and transported to the axon where it is reconverted to glutamine
vertical columns of cortex
functional units of cortex
each contains about 200 neurons
what is Brodmann’s map based on
cellular histological differences between areas
short association fibres
connect adjacent gyri within one hemisphere
long association fibres
example
connect different cortical regions within one hemisphere
e.g. arcuate fasciculus
commissural fibres
fibres that cross the midline
corpus callosum
connects homologous regions of two hemispheres with commissural fibres
projection fibres
connect cerebral cortex with subcortical brainstem and spinal cord regions
corticopetal projection fibres
input fibres such as thalamocortical axons
corticofugal projection fibres
out fibres such as corticospinal axons
aminergic axons neurotransmitter examples
dopamine
serotonin
noradrenaline
primary visual cortex location
area 17
located on both ‘banks’ of the calcarine sulcus on medial aspect of occipital lobe
primary visual cortex function
receives primary visual information form contralateral visual field
visual association area
surround primary cortical areas and are closely allied with them
“what” stream of visual processing
areas 18 and 19 and extends into inferior part of temporal lobe
concerned with interpreting the visual impulses that reach area 17
gnosis
agnosia
interpretation of objects
inability to recognise things when one sees them
primary auditory cortex location
superior part of temporal lobe
in areas 41 and 42 = Heschl’s gyri
function of primary auditory cortex
hearing receives primary auditory information form both ears
auditory association area
location
Wernicke’s speech area in the left/dominant hemisphere
located in the cortex behind the primary auditory cortex
damage to auditory association area
deafness or auditory aphasia
patient can hear speech but not understand meaning
primary somatosensory cortex location
located on the postcentral gyrus of parietal lobe
area 3, 1, 2
somatosensory association area location
superior parietal lobule, areas 5, 7
has reciprocal connexions with primary somatosensory cortex and dorsal tier of lateral thalamic nuclei
somatosensory association area role
discriminative sensation of shape, roughness, size and texture
remembering positions of objects in space
awareness of contralateral body image and location of its parts
lesion to somatosensory association area
tactile agnosia
may appear unaware of side of body opposite to lesion (hemineglect)
multimodal area of parietal lobe
inferior parietal lobe, areas 39, 40
functions with pos sup part of temporal lobe
damage to multimodal area of parietal lobe
word blindness (alexia)
inability to copy
sensory aphasia and inability to understand written and spoken word
primary motor cortex location and role
precentral gyrus, area 4
initiating voluntary movement
damage to primary motor cortex
affects contralateral side
initial hypotonia, hyporeflexia or flaccid paralysis
followed by hyperreflexia and spasticity
Babinski sign
premotor area
area 6
associated with area 4
increases in activity before a movement is carried out and helps with voluntary movements
Broca’s area location
inferior frontal gyrus in triangular and opercula regions
areas 44 and 45
Broca’s area damage
unable to talk even though muscles are not paralysed
garbled sound or one word over and over again
frontal eye field location and role
area 8
concerns with voluntary conjugate movement of eyes
prefrontal cortex
function
frontal poles and areas surrounding them
sites of personality
affective behaviour and judgement
prefrontal cortex damage
changes in mood behaviour and personality
individual neglects appearance, laughs or cries inappropriately
no appreciation of social norms
dominant hemisphere
refers to language dominance
most right handed individuals are left hemisphere dominant
larger than non-dominant hemisphere
non-dominant hemisphere
appreciation of spatial dimensions, totality of scene (including facial recognition) and non verbal symbolism
right temporal stores tone memories
damage to parietal lobe
hemi-neglect syndrome
