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mcb 163 lec#4
dorsal column
| Question | Answer |
|---|---|
| DC System 1st synapse | lower medulla |
| DC 2nd synapse | thalamus |
| DC 3rd synapse | postcentral gyrus |
| DC 4th synapse | precentral gyrus |
| Functions of the Dorsal Column system include | conscious/awareness...fine touch, pressure, moscle proprioception |
| field sobriety tests are testing | muscle proprioception (sense of relative position to neighboring parts of the body) |
| "glabrous" mechanoreceptors mean they are | hairless |
| Pacinian corpuscle are in the ______ layers | deep |
| the most well studied mechanoreceptors | pacinian corpuscles |
| Pacinian corpuscles have _______ receptive fields | large |
| pacinian corpuscles are _________ adapting | rapidly adapting |
| pacinian corpuscles detect | vibrations |
| pacinian corpuscles are wrapped in ______ layers of connective tissue | 20-70 layers |
| ruffini's endings are in the _____ layers | deep layers |
| ruffinisendings have ______ receptive fields | large RFs |
| ruffini's endings are _________ adapting | slow adapting |
| ruffini'sendings detect | skin stretch |
| meissner's corpuscles can be found in the | superficial layers of dermis on the edge of papillary ridges |
| meissner's corpuscles have _______ receptive fields | small RF (slightly larger on palms than fingertips) |
| meissner's corpuscles are ________ adapting | rapidly adapting |
| meissner's corpuscles detect | stroking and fluttering |
| Merkel's disks are located in the | superficial layer in the center of the papillary ridges |
| merkel's disks have a _________ receptive field | small receptive field |
| merkel's disks are ________ adapting | slow adapting |
| merkel's disks detect | pressure and texture-->Braille |
| Convergent excitation | many peripheral receptors come together to a single second-order sensory neuron-->RF of central neuron=RFs of all presynaptic cells |
| Surround inhibition | excitatory receptive field is surrounded by inhibitory region-->limit spread of excitation through convergent networks |
| Lateral inhibition | asymetric distributionof inhibitory interneurons-->reduce responsiveness of the relay neuron to the stimulus |
| gracile nucleus | sensation of fine touch and proprioception of the lower body (legs and trunk). |
| cuneate nucleus | carrying fine touch and proprioceptive information from the upper body (above T6, excepting the face and ear) |
| internal arcuate fibers | are the axons of second-order neurons contained within the gracile and cuneate nuclei of the medulla oblongata. |
| internal arcuate fibers___________ to form the medial lemniscus | decussate (cross over) |
| (VPL) ventral posterolateral nucleus is the nucleus of the | thalamus |
| VPL and VPM (ventral posteromedial nucleus) constitute the | ventral posterior nucleus |
| VPM is responsible for | face sensation and cranial nerve |
| 3rd synapse of DC-->___________ where the primary_______ is found | postcentral gyrus, somatosensory cortx (si) |
| there are 4 distinct cytoarchitectural regions of SI | areas 1, 2, 3a, 3b. |
| 3a & 3b receive most of the | thalamic input. |
| Si 3a | deep tissue, stretch; muscles, joints, proprioception |
| Si 3b | texture, size, shape, RA & SA; skin |
| Si 1 | texture, skin, RA |
| si 2 | deep tissues, proprioception; complex touch |
| Receptive fields from mechanoreceptors manifest themselves as _______ | cortical columns |
| stellate axons synapse on_____ | apical dendrites |
| vibrissae | whiskers |
| reorganization of the somatosensory cortex can arise both from the | loss of a limb/diget or development of specialized motor skill |
| muscimol is a GABA | agonist |
| Paying attention to what matters-->corticothalamic | feed back for error control. |
| DC nuclei/corticobulbar | feedback on limb position; planning upcoming moves. |
| Reticular formation (corticoreticular) | anticipating sensation and movement. |
| Spinal cord | rapid muscle control, voluntary |
| somatic sensory cortex contains | representations of the body surface |
| sensory thalamus and somatic sensory cortex are | the physiological manifestation of parallel pathways |
| dermatomal organization is analogous to | the cortical and spinal representation of muscle |
| center-surround organization reflects | neural integration |
| functions of corticofugal projections | feedback for error control |
| functions of corticofugal projections | preparatory for the next series of postural and locomotor events |
| functions of corticofugal projections | anticipation of and planning for future events |
| functions of corticofugal projections | focusing attention on a particular modality or set of muscles |
| corticofugal projections are | descending systems for the selective control of lower sensory or motoneurons |
| second synapse | the projection of medial lemniscal axons to the thalamus (ventral posterior nucleus) |
| third synapse | the projection of thalamic neurons to the somatic sensory cortex in the postcentral gyrus |
| fourth synapse | corticocortical projections from the postcentral somatic sensory cortex to the precentral motor cortex |
| first synapse | gracile nucleus (hindlimb representation) or cuneate nucleus (forelimb representation) or trigeminal nucleus (facial sensory representation) |
| dermatomes retain their | somatopic organization in the dorsal columns |
| slowly-adapting | tonic output, duration-sensitive, static sensors |
| rapidly-adapting | phasic output, onset-offset responsive, dynamic sensors |
Created by:
greerbaby
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