Ch.27

neocortex

cortex that has 6 layers or laminae

Histological features

thickness, cell density, etc.

Cytoarchitectonic areas

50 of them, different functions in brain

The common features of the cortical regions

1. each cortical layer has a primary source of inputs and outputs
2. each area has connections to the vertical axis and connections in the horizontal axis
3. cells with similar functions are arrayed in radially aligned groups that span all cortical layers
4. interneurons within a specific cortical laye gives rise to extensive local icons that extend horizontally in cortex, and link functionally similar groups of cells

The pulvinar thalamic nucleus

projects to parietal association cortex

The medial dorsal thalamic nuceus

projects to the frontal association cortex

The signals coming into the association cortices via thalamic nuclei have already been

processed in the primary sensory and motor areas

Corticocortical projections

* majority of input to ass cortices

ipsilateral corticocortical

* arise from 1 and 2 sensory and motor, and from other ass cortices within same hem

Interhemispheric connections

when corticocortical connections arise from cortical regions in opposite hem via corpus callosum and anterior commissure

Corticocortical connections are separated into

radial bands

Subcortical innervation of association cortices

midbrain dopaminergic, noradrenergic and serotonergic from brainstem, cholinergic in brainstem and basal forebrain

Each association area is defined by

a distinct, overlapping set of thalamic, corticocortical, and subcortical connections

DTI (diffusion tensor imaging)

ID large bundles of axons connecting brain areas

The parietal association cortex

* attention and awareness
* unilateral lesion leads to attention deficit in contralateral space
* hemispatail neglect - right
* right mediates attention to both left and right body
* left - language

The temporal association cortex

* recognition and ID of stimuli that are attended to, particularily complex ones
* lesion → agnosia

The frontal association cortex

* frontal cortex has wider repertoire of functions than any other neocortical region
* terrible personality effects
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