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SENSORY PHYSIOLOGY

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Title: SENSORY PHYSIOLOGY Author: Reagan Lake Last modified by: lake1 Created Date: 2/16/2004 6:14:35 PM Document presentation format: On-screen Show – PowerPoint PPT presentation

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Title: SENSORY PHYSIOLOGY


1
SENSORY PHYSIOLOGY
  • BIOLOGY 305 LABORATORY

2
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 define Aliasing and how to avoid it
  • How to define the Nyquest Frequency
  • How to determine a sufficient sampling rate
  • How to explain differences between analog
    digital signals
  • How to change the display time/resolution (zoom)
  • How to place marks in the record
  • How to define calculate Period, Frequency, HR
    ( units)
  • How to analyze a trace in the Analysis Window
  • How to print use the Journal

3
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

4
THIS WEEK REFLEX REACTION TIMES
  • Stimulus Response Pathways
  • Stimulus ?
  • Receptor ?
  • Afferent Path ?
  • CNS ?
  • Efferent Path ?
  • Effector ?
  • Response!

5
THIS WEEK REFLEX REACTION TIMES
  • Investigation of Reaction Times
  • Audio Stimuli
  • Prompted Patterned Sounds
  • Visual Stimuli

6
THIS WEEK REFLEXES REACTION TIMES
  • Investigation of Reaction Times
  • Possible Influences
  • Number of neurons in afferent path
  • Number of synapses
  • Distance between stimulus and sensory part of
    brain
  • Presence of mylinated axons in pathway
  • Diameter of neurons in pathway
  • Amount of processing integration in CNS
  • Efferent pathway NOT a likely influence

7
THIS WEEK REFLEX REACTION TIMES
  • Reflex
  • Stereotypical, rapid motor response
  • Does not require input from brain
  • --HOWEVER--
  • Brain can exert descending inhibition dampen
    reflex

8
NEXT WEEKTHE CRAYFISH STRETCH RECEPTOR
  • CRAYFISH
  • Invertebrate in phylum Arthropoda
  • subphylum Crustacea
  • Also includes barnacle, crab, crayfish, lobster,
    shrimp
  • Scientific name Procambarus clarkii
  • Largely aquatic
  • Characteristics include
  • Hard exoskeleton
  • Jointed, paired appendages
  • Three body regions
  • head
  • thorax
  • abdomen

9
THE CRAYFISH STRETCH RECEPTOR
  • Crayfish Nervous System
  • Bilateral Symmetry
  • Segmented Arrangement
  • Each body segment contains a ganglion
  • Axons carry info between ganglia
  • Nerve roots branch off ganglia to periphery
  • Contain sensory motor neurons

10
THE CRAYFISH STRETCH RECEPTOR
  • Purpose of Exercise
  • Gain experience w/ classic neurophys. prep.
  • Investigate stimulus-response properties of
    crayfish nervous system
  • Observe characteristics of crayfish sensory
    system
  • Encoding of stimuli
  • Sensory adaptation
  • Differentiate responses from two types of sensory
    organs

11
THE CRAYFISH STRETCH RECEPTOR
  • Muscle Receptor Organs (MROs)
  • Located in abdomen
  • Composed of a sensory neuron an associated
    muscle
  • Superficial Extensor Muscle
  • Sensory neuron has stretch-sensitive dendrites
    embedded in the muscle
  • Two types MRO1 MRO2

12
THE CRAYFISH STRETCH RECEPTOR
  • Superficial Extensor
  • Muscle
  • Two per abdominal segment
  • One on each side
  • Each contains 2 MROs,
  • One of each type

13
THE CRAYFISH STRETCH RECEPTOR
  • When Abdomen of Crayfish
  • Bends
  • S. extensor muscle is stretched
  • Sensory neuron receptors activated

14
THE CRAYFISH STRETCH RECEPTOR
  • Signaling
  • Graded potentials (GP) generated by stretch
    sensitive dendrites
  • Ion channels
  • Action potentials (APs) produced at
    spike-initiating zone

15
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

16
THE CRAYFISH STRETCH RECEPTOR
  • Major Instruments
  • Suction Electrode
  • Micromanipulator
  • Dissecting Scope

17
THE CRAYFISH STRETCH RECEPTOR
  • Major Instruments
  • Amplifier
  • Digitizer (iWorx Unit)
  • Computer (LabScribe)
  • Audio Amplifier

18
THE CRAYFISH STRETCH RECEPTOR
  • Exercises
  • Tapping Experiment
  • Elicit MRO1 MRO2
  • Increasing Stimulus Intensity
  • Observe MRO1 responses (freq) to sm, med, and
    large stimuli (stretch)
  • Adaptation Experiment
  • Observe responses to a stimuli of long duration
    and fixed intensity
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