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14 Cards in this Set
- Front
- Back
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General organization |
- 2-3 mm thick gray matter around hemispheres - folds -> 2.5 ft^2 A - primary C's - easily ID'able fxn's - association C's - multimodal processing - cytoarchitecture uniformity corresponds to fxn |
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Allocortex |
- relatively primitive A's (medial temporal lobes) - olfaction, survival (visceral, emotional rxns) -- paleocortex - piriform lobe (olfaction) -- archicortex - hippicampus (3-layered cortex) - declarative memory, spatial fxns |
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Neocortex - individual layers |
- 10-14 B neurons;l 6 layers (superficial -> deep):
1: molecular - few GABA n.'s, dendrites & axons 2/3: external graular, external pyramidal 4: internal granular - most in 1° sensory A's 5: internal pyramidal -> basal ganglia, brain stem, SC, thalamus, etc. 6: fusiform -> thalamus - 2-6: both glutamate & GABA neurons |
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Neocortex - layer structure |
- supragranular l.'s: 1-3 - 1° origin & termination of intracortical cnxn's: associational, commisural - internal granular l.: 4 - receives thalamoC input (mostly in 1° sensory C's) - infragranular l.'s: 5-6 - connect CC w/ subcortical regions (most developed in motor C A's) |
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Neuronal types in neocortex |
Spiny stellate cells, pyramidal n.'s (glutamate), nonpyramidal interneurons (GABA) - many also release neuropeptides - receptive to ascending neuromodulatory systems input (dopamine, serotonin, ACh, etc.) |
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Spiny stellate n.'s |
- prominent in l. 4 - relay cells for thalamoC input & other C cells => top-down integration |
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Pyramidal n.'s |
= main excitatory cells in l.'s 2/3, 5, 6 - prominent apical dendrite (-> l. 1) -> branches => apical tuft - numerous shorter basal dendrites - spines w/ excitatory synapses -> integration -> axon w/ collaterals (-> adjacent n.s') & long process (-> distant targets) - CC & hippocampus - rich intercnxn's -> learning, memory, abstract thought / seizures (excitotoxicity) |
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Nonpyramidal interneurons |
~ 20% of n.'s in C - many cell types, GABAergic - FFW inh.: nearby neurons w/ similar input - FB inh.: reciprocal cnxn's - benzodiazepines -> inc. GABA(A) R's |
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General Info flow w/in C |
- Thalamus -> SS (spiny stellate) cells [1° sensory A, l. 4] -> P (pyramidal) n.'s [, supragranular l.'s 2/3] -> each other & P n.'s [infragranular l.'s 5 & 6] -> brain stem/thalamus [C output] - FFW & FB inh. modulation throughout - 1° sensory -> 2°/3° sensory -> associational -> 2° motor -> 1° motor |
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Cortex as a coincidence detector |
pyramidal n. - 2 A's of synaptic input - top-down (higher C A's, non-specific thalamic nuc.) -> l. 1 (apical tufts) [expectations] - bottom-up (lower C A's, sensory thalamic nuc.) -> l. 5 (perisomatic region) [new data] => synergy -> large dendritic e- event -> AP burst: expectations match perception |
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Somatosensory C |
1° somatosensory C (SI A's 3, 1, 2) ~ postcentral gyrus <- VPL & VPM (thalamus) - granular C (prominent l. 4) - sensory homunculus (4 submaps) = somatotopic map (remapping due to Δ in motor use) 2° somatosensory C (SII, A40) ~ lower pari. lobe somatosensory association C (A's 5, 7) ~ posterior to sensory C |
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Visual C |
1° visual C (VI, A17) = striate C ~ surrounds calcarine sulcus - large granular l., dense columns of n.'s (ocular dominance columns) - visual field representation visual association A's (V2, V3; A's 18, 19) - also input from lateral geniculate (lesions -> visual agnosia; V4 - color, V5 - movement recognition) |
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Auditory C |
1° auditory C's (AI, A41) ~ traverse temporal gyri, extending to lateral fisures - contain tonotopic maps by frequency, bilateral auditory association A's (AII, A42) - interpretation of sound Wernicke's A (A22) - language understanding |
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Motor C |
1° motor C (MI, A4) ~ precentral gyrus - P n.'s ~ corticospinal tract & cortical bulbar fibers -> motor CN's (Betz cells) - somatotropic organization (homunculus; movements, rather than mm.'s represented) premotor C (A6) ~ immediately anterior supplementary motor A (MII, S-M A6) - active before movement (initiation); lesions -> abulia |
