General Properties of Sensory Receptors AdaptationWhen a maintained stimulus of constant strength is applied to a receptor,the frequency of the action potentials in its sensory nerve declines over aperiod of time-Tonicreceptors:ProduceconstantrateoffiringaslongasstimulusisappliedSlow-adaptingPain-Phasicreceptors:Burst ofactivitybut quicklyreducefiring rate (adapt)ifstimulusmaintainedFast-adaptingSensoryadaptation:temperature
General Properties of Sensory Receptors • Adaptation When a maintained stimulus of constant strength is applied to a receptor, the frequency of the action potentials in its sensory nerve declines over a period of time - Tonic receptors: Produce constantrate of firing as long as stimulus is applied Slow-adapting Pain - Phasic receptors: Burst of activity but quickly reduce firing rate (adapt) if stimulus maintained Fast-adapting Sensory adaptation: temperature
General Properties of Sensory ReceptorsCopyrighteTheMcGraw-Hill CoquiredforreproductionordisplayRapidlyadaptingActionpotentialsStimulusintensityTimeSlowlyadaptingActionpotentialsStimulusintensityTime
General Properties of Sensory Receptors
General Properties of Sensory ReceptorsRegardless of how a sensory neuron is stimulated,only one typeofsensationwillbeperceivedmr.tses.ntpc.edu.tw
General Properties of Sensory Receptors • Regardless of how a sensory neuron is stimulated, only one type of sensation will be perceived mr.tses.ntpc.edu.tw
General Properties of Sensory ReceptorsThespecificityofsensorypathwaysisestablishedinseveralways:1) Each receptor is most sensitive to a particular type of stimulus.2)Astimulus above threshold initiates action potentials in a sensory neuron thatprojects tothe CNS.3)Stimulus intensity and duration are coded inthepatternof action potentialsreaching the CNS.4) Stimulus location and modalityare coded according to which receptors areactivated or (in the case of sound) by the timing of receptor activation.5)Eachsensorypathwayprojectstoaspecificregionofthecerebralcortexdedicated to a particular receptive field.The brain can then tell the origin of eachincoming signal
General Properties of Sensory Receptors The specificity of sensory pathways is established in several ways: 1) Each receptor is most sensitive to a particular type of stimulus. 2) A stimulus above threshold initiates action potentials in a sensory neuron that projects to the CNS. 3) Stimulus intensity and duration are coded in the pattern of action potentials reaching the CNS. 4) Stimulus location and modality are coded according to which receptors are activated or (in the case of sound) by the timing of receptor activation. 5) Each sensory pathway projects to a specific region of the cerebral cortex dedicated to a particular receptive field. The brain can then tell the origin of each incoming signal
OutlineSensory functions of Nervous System-GeneralPrinciplesSection B. Specific Sensory system- VisionCentralsulcusSomatosensory-HearingFrontal lobecortexassociationParietallobeareaassociation-VestibularSystemAuditoryareacortexTastecortex-SomaticSensationVisualcortex-ChemicalSensesOccipitallobeassociationareaTemporal lobeassociationarea
Outline • Sensory functions of Nervous System - General Principles • Section B. Specific Sensory system - Vision - Hearing - Vestibular System - Somatic Sensation - Chemical Senses