SENSORY PHYSIOLOGYANNOUNCEMENTSLAB PRACTICALSlide 4THIS WEEK: REACTION TIMESTHIS WEEK: REACTION TIMESTHIS WEEK: REFLEXESNEXT WEEK: THE CRAYFISH STRETCH RECEPTORNEXT WEEK: THE CRAYFISH STRETCH RECEPTORTHE CRAYFISH STRETCH RECEPTORTHE CRAYFISH STRETCH RECEPTORSlide 12Slide 13THE CRAYFISH STRETCH RECEPTORSlide 15Slide 16Slide 17Slide 18SENSORY PHYSIOLOGYBIOLOGY 305 LABORATORYANNOUNCEMENTS•Lab Practical is NEXT Week!•Check course web site for schedule of open lab hoursLAB PRACTICAL•Be Sure YOU Know:LAB PRACTICAL•How You Loose Points:THIS WEEK: REACTION TIMESInvestigation of Reaction Times:•Audio Stimuli•Visual StimuliInvestigation of Myotactic ReflexTHIS WEEK: REACTION TIMESInvestigation of Reaction Times:•Auditory stimulus takes approx. visual stimulus takes approx. •Influences:THIS WEEK: REFLEXESReflexes:•Stereotypical, rapid motor response•Do not require input from brainNEXT WEEK: THE CRAYFISH STRETCH RECEPTORCRAYFISH:•Invertebrate•Also includes: crab, lobster, shrimp•Scientific name:•Largely aquatic •Characteristics include:NEXT WEEK: THE CRAYFISH STRETCH RECEPTOR The Neuron:•Excitable cell•Basic unit of communication in nearly all nervous systemsNeuron Anatomy: •Dendrites•Cell body•AxonTHE CRAYFISH STRETCH RECEPTORCrayfish Nervous System:•Bilateral Symmetry•Segmented Arrangement:•Each body segment contains ganglion•Axons carry info between ganglia•Nerves branch off ganglia to periphery•Contain sensory + motor neuronsTHE CRAYFISH STRETCH RECEPTORPurpose of Exercise:•Experience classic neurophys. prep.•Investigate stimulus-response properties of crayfish nervous system•Observe characteristics of a sensory system:•Differentiate responses from two types of sensory organsTHE CRAYFISH STRETCH RECEPTORMuscle Receptor Organs (MROs):•Two types:•Composed ofTHE CRAYFISH STRETCH RECEPTORSuperficial Extensor Muscle:•Two per abdominal segment•Each contains 2 MRO neuronsTHE CRAYFISH STRETCH RECEPTORWhen Abdomen of CrayfishBends:THE CRAYFISH STRETCH RECEPTORSignaling:•Electrical signals are generated byTHE CRAYFISH STRETCH RECEPTORFor This Exercise:•We’ll record extracellularly from a nerve that carries sensory info from MROs to CNS •Accomplished by curling crayfish tail to stimulate sensory neuronsTHE CRAYFISH STRETCH RECEPTORMajor Instruments:THE CRAYFISH STRETCH RECEPTORExercises:•Stimulus Intensity •Adaptation •Tapping