Term
| intracortical synaptic organization |
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Definition
| information processing in a small volume of cortex |
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Term
| interareal synaptic organization |
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Definition
| the interconnection of functionally different cortical units with long association & commissural fibers |
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Term
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Definition
| the six layers in which neurons are arranged & are oriented parallel to the surface of the cortex |
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Term
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Definition
| how neurons are organized oriented perpendicular to the cortical surface |
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Term
| About how many neurons are cortical pyramidal cells? |
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Definition
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Term
| What is the typical anatomy of a typical pyramidal cell? |
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Definition
| a long axon arising from the base of the pyramid & a long apical dendrite that extends toward the cortical surface; it extends through several layers superficial to the layer in which the cell body is located |
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Term
| Do pyramidal cells have a large or small number of dendritic spines? |
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Definition
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Term
| What is characteristic of the most superficial cortical layer (layer 1) (the molecular layer)? |
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Definition
| rich in fibers but has few neurons |
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Term
| What is characteristic of layer 2 (the external granular layer)? |
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Definition
| contains densely packed small cell bodies |
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Term
| What layer is layer 4 (the internal granular layer) similar to in terms of anatomy? |
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Definition
| layer 2 (the external granular layer) |
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Term
| What is the difference in anatomy between layer 3 (the external pyramidal layer) & layer 5 (the internal pyramidal layer)? |
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Definition
layer 3 = medium-sized pyramidal cells
layer 5 = large pyramidal cells |
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Term
| What is characteristic of layer 6 (the multiform layer)? |
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Definition
| many cells wit spindle-shaped bodies |
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Term
| What is the difference in the role of layers 2 & 4 and the role of layers 3 & 5? |
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Definition
2 & 4 = mainly receiving (most developed in the primary sensory areas)
3 & 5 = mainly efferent (send their axons out of the part of the cortex in which they are located) |
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Term
| Where do the pyramidal cells of layer 5 send their axons? |
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Definition
| primarily to subcortical nuclei (particularly well developed in the motor cortex) |
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Term
| Where does layer 6 send many axons? |
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Definition
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Term
| Where do pathways that convey precise sensory information primarily end? |
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Definition
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Term
| What 2 layers do association fibers preferentially end? |
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Definition
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Term
| Where do subcortical afferents with modulatory effects especially end? |
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Definition
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Term
| Where do pyramidal cells send their axon? |
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Definition
| toward the white matter to reach other parts of the cortex or subcortical cell groups |
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Term
| What is the significance in that projection neurons send recurrent collaterals before the axon leaves the cortex? |
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Definition
| it can influence the level of activity among the cortical neurons in their vicinity |
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Term
| How many types of interneurons are there? |
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Definition
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Term
| What do vertically oriented axons ensure? |
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Definition
| the communication among neurons within a narrow cortical cylinder (column) |
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Term
| What do horizontal axonal branches mediate? |
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Definition
| communication among neurons in different columns |
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Term
| What do horizontal intracortical connections do in sensory cortical areas? |
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Definition
| they mediate lateral inhibition which increases the spatial resolution of the sensory information |
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Term
| How do horizontal intracortical connections contribute to cortical plasticity? |
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Definition
| they modulate the size of the receptive fields of cortical neurons |
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Term
| What is the main neurotransmitter for projection neurons (those sending their axons to subcortical nuclei & those forming association or commissural connections)? |
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Definition
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Term
| What is involved with glutamate released from pyramidal-cell collaterals that binds to N-methyl-D-aspartate (NMDA) receptors? |
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Definition
| they are involved in plastic changes related to learning & restitution after brain damage |
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Term
| Are spiny stellate cells excitatory or inhibitory? |
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Definition
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Term
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Definition
| interneurons that have few spines |
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Term
| Do most of the GABAergic interneurons also contain one or several neuropeptides? |
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Definition
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Term
| What contributes to epilepsy? |
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Definition
| selective loss of GABAergic cortical interneurons |
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Term
| What is the main job of inhibitory interneurons? |
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Definition
| to focus the excitatory signals & to limit the activity of the projection neurons |
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Term
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Definition
| when an inhibitory interneurons inhibit other inhibitory interneurons |
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Term
| Do glutamate thalamocortical fibers act through AMPA receptors or NMDA receptors? |
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Definition
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Term
| What type of receptors do pyramidal cell collaterals act on? |
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Definition
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Term
| What results from simultaneous activation of a cortical neuron from the thalamus & from other cortical neurons? |
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Definition
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Term
| What does the response of so many cortical neurons depend on? |
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Definition
| the context of a stimulus |
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Term
| How do horizontal connections affect receptive fields of cortical neurons? |
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Definition
| they ensure that the receptive fields are not static but subject to modification by inputs from their neighbors |
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Term
| What causes cortical plasticity? |
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Definition
| changes in the synaptic efficacy of horizontal connections |
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Term
| 4 types of afferent connections of the cerebral cortex |
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Definition
1. precise, topographically organized connections from the "specific" thalamic nuclei
2. diffusely organized connections from the intralaminar thalamic nuclei & several other subcortical nuclei
3. association fibers
4. commissural fibers |
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Term
| 2 types of efferent connections of the cerebral cortex |
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Definition
1. subcortical
2. corticocortical |
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Term
| What does it mean that the corticocortical connections are "reciprocal"? |
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Definition
| an area receives fibers from the same areas to which it sends fibers |
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Term
| What is the difference in the role of the ventral posterolateral nucleus, the lateral geniculate body, & the medial geniculate body? |
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Definition
ventral posterolateral nucleus = receives afferents from somatosensory pathways & projects to the SI
lateral geniculate body = receives afferents from the retina & projects to the striate area
medial geniculate body = the last station in the auditory pathways & sends efferents to the AI |
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Term
| What pathway depends on the ventrolateral nucleus & the ventral anterior nucleus? |
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Definition
| they are the relay stations to the pathways from the cerebellum & the basal ganglia to the motor & premotor cortical areas |
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Term
| How are the anterior thalamic nucleus VS the mediodorsal nucleus involved in limbic stuff? |
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Definition
anterior = receives afferents from the mammillary nucleus & projects to the cingulate gyrus
mediodorsal = relays signals from the amygdala to the frontal lobes |
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Term
| Where does the contralateral nucleus send fibers? |
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Definition
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Term
| How do intralaminar nuclei affect cortical neurons? |
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Definition
| they exert effects on the excitability of cortical neurons |
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Term
| What is the difference in where dopamine fibers from the VTA end & where noradrenergic fibers from the locus coeruleus end? |
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Definition
dopamine = prefrontal & temporal neocortex
noradrenergic = the central region |
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Term
| Do the thalamic nuclei receive a lot or a few back-projections from the cerebral cortex? |
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Definition
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Term
| What do the longest association fibers interconnect? |
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Definition
| functionally related areas in different lobes |
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Term
| Where do fibers going outward (feedforward connections) mainly arise & end? |
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Definition
arise = layer 3
end = layer 4 |
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Term
| Where do fibers going backward (feedback connections) arise & end? |
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Definition
arise = deep layers
end = the most superficial layers |
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Term
| What are the outward connections from the sensory areas concerned with? |
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Definition
| segregation & specific convergence of sensory information |
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Term
| What are backward sensory connections concerned with? |
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Definition
| context-dependent modifications of sensory processing |
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Term
| Where do most commissural fibers pass through? |
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Definition
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Term
| What do commissural fibers interconnect? |
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Definition
| corresponding areas in the two hemispheres |
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Term
| 3 places that are basically devoid of commissural fibers |
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Definition
1. striate area
2. MI representing distal parts of the extremities
3. SI representing distal parts of the extremities |
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