Cerebrum Flashcards
Define the three types of mammalian cortex
- Archicortex (3 layers, hippocampus)
- paleocortex (3-5 layers, olfactory/pyriform cortex)
- neocortex (6 layers, everything else)
What are the major principle cells of cerebral cortex?
- Pyramidal cells (excitatory, 2/3 of all neurons, glutamatergic)
- Fusiform cells (atypical, irrgular, elliptical)
What are the major interneurons in the cerebral cortex?
- Stellate (excitatory, layer IV, star)
- Basket cell (inhibitory, lateral branching axons)
- Retzius-cajal cells (aka horizontal cells, molecular layer)
- Cells of martinotti (deep layers, axons project up to plial layer)
What are the 6 layers of cortex & the cells found in each
- Molecular
* synaptic layer, retzius-cajal cell bodies, terminal dendrites/axons, pyramidal dendritic branches) - External Granular
* small pyramidal & interneurons - External Pyramidal
* small/medium pyramidal (forms association & commissural fibres) - Internal Granular
* stellate, some other interneurons & pyramidal - Internal Pyramidal
* large pyramidal (form projection fibres) - Multiform
* cells of martinotti, fusiform, few interneurons, pyramidal cells that project to thalamis/claustrom
Describe some of the variations in cytoarchitecture and how they can be used to identify different regions of the cerebrum
- primary visual, auditory and somatosensory cortex (layers 2-5 merge into one)
- Primary motor & premotor (layers 2-6 merge into one)
Describe the organisation of intracortical circuits.
- Cortical cell axons excite pyramidal apical dendrite
- input from thalamus excites pyramidal basal dendrites & stellate cells
- stellate cells excite pyramidal cells
- input from thalamus & pyramidal cells excite basket cells
- basket cells inhibit currounding pyramidal cells
Describe and identify the cerebral localisation and circuitry of general somatic sensation
Primary somatic = Brodman 1,2,3 (postcentral gyrus)
* input from ventral posterior thalamus
* homunculus (localisation of sensation)
Somatic association = Areas 5&7 (superior parietal lobule & precuneus)
* input from primary somatic, lateral posterior thalamus and pulvinar
* allows object recognition without visual aid
Describe and identify the cerebral localisation and circuitry of vision
Primary visual = area 17 (surrounding calcarine sulcus)
* input form lateral geniculate thalamus via geniculocalcarine tract
* LHS visual field represented in RHS brain (and vice versa)
Visual association = areas 18 & 19 (occipital surrounding primary area)
* input from contralateral area 17, thalamus & pulvinar
* complex visual processing, recognition & significance
Describe and identify the cerebral localisation and circuitry of hearing
Primary auditory = areas 41 & 42 (ventral wall of lateral sulcus, herschl’s convolutions)
* input from medial geniculate thalamus
Describe and identify the cerebral localisation and circuitry of taste
Taste = Area 43 (inferior postcentral gyrus)
* input from medial ventral posterior thalamus
Describe and identify the cerebral localisation and circuitry of olfaction
Olfactory = Area 34 (limen insulae & uncus)
* input from olfactory tubercle & medial dorsal thalamus
Describe and identify the cerebral localisation and circuitry of vestibular
No defined cortical area.
* intraparietal sulcus (in somatosensory cortex) & posterior insular
* integrates vestibular & proprioceptive signals
Describe and identify the cerebral localisation and circuitry of motor systems
Primary moto = area 4 (precentral gyrus)
* input from other motor cortex, posterior ventral lateral thalamus
Supplementary/cingulate motor
* area 6 (PMA/SMA) & anterior cingulate
* Area 8 frontal eye fields for control of eye movements.
* input from many cortical areas, ventral anterior thalamus & ventral lateral thalamus
Identify the localisation of language areas that control both comprehension of language and motor speech areas.
Wernicke’s Area
* Area 22 - Left posterior superior temporal gyrus
* receptive language area - comprehension of spoken and written language
Broca’s area
* Areas 44 & 45 - inferior frontal gyrus
* expressive speech area - motor speech