Sensory processing: touch and pain Flashcards
describe sensory transduction
the process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across it’s membrane
describe receptor potentials
a local change in the resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of action potentials
describe receptor threshold
when a receptor has reached it’s threshold, which is the stimulus that is just adequate to trigger an action potential, the axon will produce one or more action potentials
explain sensory adaptation
bottom up processes and top down processes
describe bottom-up processes
sensory systems emphasize change in stimulation, tonic receptors don’t adapt while phasic receptors do
describe top-down processes
brain suppresses sensory signals
explain the receptive field of a sensory neuron
the spatial region in which a stimulus influences a neuron, the target neuron responds by altering the firing rate
understand the general sequence of sensory processing from the sensory receptor to cortex and the ways in which the sensory message can be coded for intensity and location
each sensory modality sends signals to brain via labeled line that remain separate from the signals from other sensory modalities
Coding?
coding of electrical activity allows sensory systems to convey complex information
intensity?
firing rate and pattern of firing, plus number of neurons firing and range fractionation
location?
spatial mapping via labeled lines at each stage of processing
understand the transduction of somatosensory stimuli
responsible for touch, body awareness, and pain, receptors broadly distributed and respond to many kinds of stimuli
muscle spindle
proprioception, alpha A axon type,
Pacinian corpuscles, Ruffini endings, Merkel discs, Meissner corpuscles
touch, A beta axon type
free nerve endings
pain temp and itch, A delta and C axons
somatosensory dorsal column pathway
unipolar sensory neurons axons enter spinal chord in dorsal roots, axons ascend to brain in dorsal white matter, synapse in the medulla, axons leaving medulla cross midline an ascend to thalamus, from thalamus information gets sent to somatosensory cortex
nociceptors
signals travel on unmyelinated C fibers, lightly myelinated A fibers
mechanical- severe or rapid stretch opens channels
chemical- specific molecules open channels
thermal- heat opens channels
polymodal- detect multiple types of pain stimuli
