6 layer cortex 36 billion cortical neurons 50k

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-> 6 layer cortex: 36 billion cortical neurons -> 50k neurons/mm^3 -> 3mm thick cortex -> 1200 cm^2 cortical surface per hemisphere - Mesocortex: 6 layers, less well structured - Allocortex: 1-4 layers (3 layers) – hippocampus Cortical columns - A group of neurons in the cortex of the brain that can be successively penetrated by a probe inserted perpendicularly to the cortical surface, and which have nearly identical receptive fields.
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cortical column- reveals cellular structure of the cortical neurons in the cortex (6 layers) - A cortical column is a section that spans the height of cortical gray matter. - These columns are sometimes thought of as functional units of cortex because the within column connections suggest that neurons within a column work together. It also refers to the cortical columns in the visual cortex which has functional meaning: Ocular Dominance columns vs Orientation Dominance columns (more details in the vision section) - Each columns has two “properties” : - Ocular : left eye and right eye - Orientation: horizontal, vertical - mostly anatomy use - Visual cortex (V1)-> cortical column has its functional meaning (orientation column) - Column shows cellar structure with different layer Rostral=anterior, caudal=posterior, dorsal, ventral, anterior , posterior. superior, inferior Coronal, sagittal, axial, horizontal, midline=mid- sagittal , lateral, medial Brodmann’s areas (not specific numbers)
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- Brodmann divide brain area based on cell structures - All neo-cortex has 6 layers; while the distribution of each layers are different across different brain areas - Neurons with same cellular structure are categorized into same category/area - Different parts of the cereberal cortex are involved in different cognitive and behavior functions. - Many of those brian areas defined by Brodmann have their own complex internal structures. In a number of cases, brain areas are organized into topographic graphs, eg primary visual cortex and primary somatosensory cortex - But for auditory cortex, it’s mapped tonotopically Cytoarchitectonics - structures in neurons One of the ways to parse brain, by obtaining sections of the brain and staining them with chemical agents that reveal how neurons are “stacked” into layers It is the study of the cellular composition of the body’s tissues under the microscope The local architecture of neural cell connecitons, observed under the microscope Basis for brodmann cortical area subdivsions Example: stria of gennari Ribon of highly stained cells Lesion - localized brain damage caused by any change Localization of brain function : - Single Centers for vision, language, social behavior, etc. do not exist - Networks or Systems composed of several interconnected brain units, support function.
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  • Spring '17
  • sommers
  • brain activity, visual cortex

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