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26 Cards in this Set
- Front
- Back
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somatosensory lemniscal channel
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neuronal system that conveys sensory information will will enter into conscious experience
-foot touched, sensory neuron sends to spinal cord, synapses in medulla, then to thalamus, sent to somatosensory cortex to responding region |
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-represents the density of sensory receptors in your skin
-map of somatic sensory cortex -used as a result of the failure of somatotopic maps |
homonculus
-enlarged face and hands |
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where is the primary somatic sensory cortex located on the brain?
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postcentral gyrus of the parietal lobe
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why does it make sense that the primary somatic sensory cortex is on the parietal lobe?
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the parietal lobe is responsible for integrating different modulations of the brain
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which has more sensory receptors? your fingers or arms?
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fingers
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describe the lemniscal channel system
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sensory fibers pass through dorsal root ganglia to the spinal cord, do not synapse until the medulla, then continue to the thalamus and synapse again, project to the primary somatic sensory cortex.
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the region of a receptive surface (skin) within which a specific stimulus elicits the greatest action potential response from sensory cells
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receptive field
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the area of the skin surface over which stimulation results in a significant change in the rate of action potentials
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receptive field
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"the average size of the afferent receptive fields reflects the density of afferent fibers supplying the area"
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got it?
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receptive fields in regions with dense innervation are typically ____ compared to regions with less innervation
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smaller
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the minimum inter stimulus distance required to perceive two simultaneously applied stimuli as distinct
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two point discrimination threshold
-changes dramatically in different areas of the body |
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more cortical representation given to areas with significant sensory input
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in humans, face and speech
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two ways sensory afferents are differentiated
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1. receptive field size
2. temporal dynamics of response to stimulus |
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2 factors that affect two point discrimination threshold
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receptive field size and innervation density
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afferents that continue responding to a stimulus
-better suited for? |
slowly adapting afferents
-better suited to provide info about spacial attributes of a stimulus |
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afferents that stop responding to a continued stimulus
-better suited for? |
rapidly adapting afferents
-better suited to convey info about changes in ongoing stimulation |
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the dorsal column-medial lemniscal system carries sensory info from where on the body?
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posterior third of the head and the rest of the body
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the trigeminothalamic system carries info from where to the brain?
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tactile info from the face
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dorsal column lemniscal crosses in the brain contributes to left brain controlling right body
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ok
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two tracts of the dorsal column medial lemniscal system
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1. gracile tract - lower limbs
2. cuneate tract - upper limbs, trunk, and neck |
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areas in the S1 cortex that respond to cutaneous stimuli
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areas 3b and 1
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areas in S1 cortex that respond to position of the body (proprioceptors)
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area 3a
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area in S1 that responds to tactile and proprioceptive stimuli
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area 2
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if a nerve is cut, what happens to the receptive field of that particular nerve?
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expands immediately and continues to expand for at least 2-3 weeks
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how does the phantom limb sensation work?
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after an amputation, the neuron might start responding to another neighboring neuron due to axonal sprouting
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why does this phantom limb decrease over time?
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the area innervated in the cortex will disappear after not a lot of usage and will be taken over by other representation of another body part
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