SENSORY PHYSIOLOGY

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SENSORY PHYSIOLOGY

• BIOLOGY 305 LABORATORY

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ANNOUNCEMENTS

• Lab Practical is THIS Week!
• Check course web site for schedule of open lab
  hours

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LAB PRACTICAL

• Be Sure YOU Know
• How to log on
• How to load software settings (tutorial)
• How to set up hardware
• How to use the finger pulse transducer (w/o
  noise)
• How to avoid aliasing
• How to determine a sufficient sampling rate
• How to change the display time/resolution (zoom
  in/out)
• How to define calculate Period, Frequency, HR
• How to analyze a trace in the Analysis Window
• How to print use the Journal

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LAB PRACTICAL

• How You Loose Points
• Forgetting to turn on iWorx Box
• Noisy trace
• Needing assistance from TA
• Not completing exercise on time
• Errors in calculations equations
• Omitting units

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REVIEW OF LAST WEEK REACTION TIMES

• Stimulus Response Pathways
• Stimulus ?
• Response!

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LAST WEEK REACTION TIMES

• Investigation of Reaction Times
• Audio Stimuli
• Prompted Patterned Sounds
• Visual Stimuli

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LAST WEEK REACTION TIMES

• Investigation of Reaction Times
• Possible Influences

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LAST WEEK REFLEXES

• Reflex
• Stereotypical, rapid motor response

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THIS WEEK THE CRAYFISH STRETCH RECEPTOR

• CRAYFISH
• Invertebrate in phylum
• Subphylum
• Also includes crab, lobster, shrimp
• Scientific name
• Largely aquatic
• Characteristics include
• Hard exoskeleton
• Jointed, paired appendages
• Three body regions

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THE CRAYFISH STRETCH RECEPTOR

• Crayfish Nervous System
• Bilateral Symmetry
• Segmented Arrangement
• Each body segment contains ganglion
• Axons carry info between ganglia
• Nerve roots branch off ganglia to periphery

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THE CRAYFISH STRETCH RECEPTOR

• Purpose 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
  organs

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THE CRAYFISH STRETCH RECEPTOR

• Muscle Receptor Organs (MROs)
• Located in abdomen
• Two types
• Composed of sensory neuron associated muscle

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THE CRAYFISH STRETCH RECEPTOR

• Superficial Extensor Muscle
• Two per abdominal segment
• One on each side
• Each contains 2 MROs,
• One of each type

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THE CRAYFISH STRETCH RECEPTOR

• When Abdomen of Crayfish
• Bends
• S. extensor muscle is stretched
• Sensory neuron receptors activated

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THE CRAYFISH STRETCH RECEPTOR

• Signaling
• Electrical signals are generated
• Action potentials (APs) produced at trigger zone

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THE CRAYFISH STRETCH RECEPTOR

• For This Exercise
• Well record extracellularly from nerves that
  carry sensory info from MROs to CNS
• Accomplished by curling crayfish tail to
  stimulate sensory receptors

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THE CRAYFISH STRETCH RECEPTOR

• Major Instruments

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THE CRAYFISH STRETCH RECEPTOR

• Exercises
• Stimulus Intensity
• Observe MRO1 responses to various stimuli
  (stretch)
• Adaptation
• Observe response to stimulus of long duration and
  fixed intensity
• Tapping Experiment
• Elicit MRO2