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Flashcards in Sensory and Motor Pathways Deck (17):

Features common to all sensory systems

1. change of a sensory stimuli into a graded change in membrane potential
2. change in membrane potential -> change in neuronal firing rate
3. Info comes into CNS on "labeled lines" (different distinguishable neurons), combined and further processed to generate output responses


common channels underlying sensory responses?

Cation P-loop channels

CNG Channels - visual
Trp - chemicals and temperature



with a sustained stimulus, response will peak, then after a while will decrease (ex: staying out in a dark night then coming into light and saying HOLY SHIT THAT'S FUCKIN BRIGHT...then you get used to it)


What regulates adaptation?



How does adaptation work?

Partial densensitization. Sensitive during weak stimuli and toned down in prolonged strong stimuli, to maintain dynamic range


Why is sensory info segregated? (labeled lines)

labeled lines ensure that the CNS knows what type of info it is receiving



"pepper" channel. activates heat sensitive channel that responds to "burning" temperatures


How do different tastes work?

Different tastes, same transduction...due to the differential expression of receptors leading to distinct info being sent to CNS


receptive field

set of stimuli that affect the firing of a sensory neuron. COntain both positive and negative stimuli


Common organization for receptive fields

center/surround organization with opposing responses in the two areas...

stimuli that are focused on the positive area of the receptive field are detected more strongly than stimuli that are constant across receptive field


Touch receptive fields

Large behind legs, small on finger


Visual receptive fields

large in periphery, small in fovea


Where in brain does sensory info enter?

distinct regions of CORTEX


Area of cortex and sensory info?

area of cortex devoted to info coming in from different locations is related to complexity of receptive field coming from that area

ex: foveal representation in cortex is much larger than the area of visula space being covered. Also, speech processing areas are greatly expanded


How do motor units work?

motor neurons connect to a subset of muscle fibers in a single muscle....fibers are controlled as a unity by motor neuron....each muscle recieves input from a single motor neuron....muscles with finer control have smaller motor units


Feedback in motor responses

sensors in series = info about muscle forces

sensors in parallel = info about muscle length


What is a reflex?

simple motor program triggered by sensory input