Principles of Sensory Systems/Touch & Pain (CH. 8)

law of specific nerve energies
Click the card to flip 👆
1 / 27
Terms in this set (27)
law of specific nerve energies
specific receptors and neural channels for each sense are unique to each sense
-both independent and can only produce 1 sensation
lateral inhibition
a common theme of sensory systems-input is non-linear- this phenomenon in vision enhances objects to be more defined than they should be
adequate stimulus
the stimulus which activates a sensory receptor
transduction
the conversion of physical energy by a receptor into an electrochemical pattern in neurons
somatosensation
the sense of touch- detection of body sensations (including touch and pain)
labeled-line coding
the concept that the brain recognizes distinct senses because separate pathways convey action potentials for separate types of sensory info.
receptor potential (generator potential)
initiation of an action potential in a receptor cell
pacinian corpuscle
prototype touch receptor which detects sudden displacement or high-frequency vibrations on the skin
-contains an online-like outer structure
-sudden/ or vibrating stimulus bends the membrane and increases the flow of sodium ions to trigger an action potential
*located in hypodermis layer
what are the steps in somatosensation at receptor?
1. pacinian corpuscle changes conformation when pressure is applied, thus opening Na+ channels
2. the pac. corpuscle produces a graded electrical potential (similar to an EPSP)
3. when the potential is big enough, the receptor reaches threshold, and then generates an action potential
adaptation
the progressive loss of response to a maintained stimulus
*key for representing changes in one's environment
tonic receptorsreceptors which show slow or no decline in AP frequencephasic receptorsreceptors which display adaptation and decrease frequency of APswhat are the 3 mechanisms for detecting changes in the intensity of touch stimulation?1. single neuron responses 2. different population responses 3. different types of tactile sensory receptorsreceptive fieldregion of space in which the presence of a stimulus will alter firing for that sensory neuron -somatosensory systems show center-surround receptive fieldsprimary somatosensory cortex (s1)cortical receptive field which receives touch information from opposite sides of the bodysecondary somatosensory cortex (s2)cortical receptive field which maps both sides of the bodydorsal column systemsomatosensory information ascents ipsilaterally (same side), crosses the midline to the contralateral side in the brain stemnociceptorsthe sensory receptor that conveys pain-related informationtransient receptor potential vanilloid type 1 (TRPV1)a sensory receptor which conveys pain info. relevant to heatTRP2sensory receptor which detects hotter temperatures than TRPV1a-delta fiberslarge, myelinated fibers; convey info. rapidly to spinal cord and brainc- fiberssmall, unmyelinated fibers; convey info. more slowly to spinal cord and brainSCN9 geneencodes a Na+ channel in nociceptors and people with defects in this gene can not feel any painspinothalamic tracta pain pathway to the brain- pathway ascends in this tract, already contralateral once entering into spinal cord -pain sensitive cells in the spinal cord relay info. to several areas of the brainperiaqueductal gray area (PAG)an inhibitory pathway for pain processing-a midbrain structure that exerts descending inhibitory control over afferent pain pathways -electrical stimulation or activation of opiate receptors in PAG leads to analgesia (pain relief)placebodrug or other procedure with no pharmacological effect -may decrease pain perception by activating emotional response systems that diminish pain perception and not the actual pain sensation itselfperipheral mechanisms of bodyalso increases sensitivity to pain -damaged or injured tissue releases histamine (inducing inflammation and swelling), nerve growth factor, and other chemicals that increase the number of Na+ gates in nearby pain receptors