Lecture 15, 16 Oct 2003 Chapter 11, Movement and Behavior Vertebrate Physiology ECOL 437

1. Lecture 15, 16 Oct 2003 Chapter 11, Movement and Behavior Vertebrate Physiology ECOL 437 University of Arizona Fall 2003 instr: Kevin Bonine t.a.: Bret Pasch

2. Vertebrate Physiology 437 1. Behavior Initiation (CH11) 2. Announcements exam next Tuesday seminars etc. 3. Jokes from the audience... Fig. 11-12 Randall et al. 2002

3. Chapter Eleven Animal Behavior, Neurobiology ~Behavior Initiation Complex Bring together nervous, endocrine, muscular systems, etc. Respond to situation(s) Parallel Processing Complicated Neuronal Circuitry Reflexes / Learned / Plasticity

4. Simple Reflexes – basis of neuronal circuitry Reflex Arc, Stereotypic Behavior Stretch receptor activates 1a-afferent neuron e.g., stretch reflex (patellar tendon) - Tonic tension in muscle - Important for maintenance of posture via negative feedback - Only 2 neurons required Alpha-motor neuron activates quadriceps - monosynaptic reflex Sherwood 1997 (see 11-1 in Eckert)

5. Simple Reflexes Stretch receptor = muscle spindle organ - containsintrafusal fibers (as opposed to extrafusal) - Sensitive to stretch (stretch -> APs) - Need to be reset for new muscle length - Gamma-motor neurons innervate spindle

6. 1. 1a-afferent neuron 2. Alpha-motor neuron 3. Gamma-motor neuron Sherwood 1997 (see 11-1 in Eckert) c. Contracted muscle without ‘reset’ muscle spindle

7. Simple Reflexes + Other neurons become involved as well: • - 1a-afferents inhibit the antagonist muscle • (Knee flexor ~hamstring) - Conscious decision to bend leg etc. Fig. 11-2 Randall et al. 2002 - Limb

8. Law of Nerve-Specific Energy dorsal Action Potentials and Graded Potentials don’t convey specific information. ventral Rather, the geographic connections, summation of different inputs, and modulation are important for correct response Fig. 11-12 Randall et al. 2002

9. Sensory Neurons Individual Receptors Variable Process thousands of inputs to generate ‘scene’ p. 441 Randall et al. 2002 Fig. 11-13 Randall et al. 2002

10. Sensory Networks and Lateral Inhibition (11-14) Fig. 11-14 Randall et al. 2002 Helps define edges in vision

11. Horseshoe crab More APs from single ommatidia withoutlateral influence (11-14) Fig. 11-14 Randall et al. 2002

12. Vertebrate Visual System Retina --> Visual Cortex contralateral (11-17) ipsilateral Layers of cells in between Fig. 11-17 Randall et al. 2002

13. Convergence and Divergence Fig. 11-18 Randall et al. 2002 Processing in Retina and in Brain 1st, 2nd, 3rd Order Photoreceptors Lateral Interxns Horizontal Cells Bipolar Cells Amacrine Cells Ganglion Cells (optic nerve) To Brain (11-18)

14. Fig. 11-19 Randall et al. 2002 Lateral inhibition activation Dark Current! (hyperpolarize in light) 1st Order - Hyper- or De- Polarizing 2nd Order - Convergence/ Divergence (minimal in fovea= acuity) - Outside fovea, many photoreceptors per ganglion 3rd Order (11-19)

15. Visual Receptive Field - 2 parts: Center, Surround Size and area innervating a givenganglion cell - 2 kinds: On or Off 1 or 2 photoreceptors  2mm diameter Fig. 11-20 Randall et al. 2002 Lots lateral inhibition (11-20)

16. Visual Receptive Field - Mediated by bipolar cells that either hyper- or de- polarize - Center, Surround - On or Off receptor horizontal bipolar ganglion Fig. 11-21 Randall et al. 2002

17. Simple Cells in Visual Cortex respond to linear arrangements of receptive fields in retina ‘On’ example: (11-24) Fig. 11-24 Randall et al. 2002

18. ‘On’ example: (11-23) Fig. 11-23 Randall et al. 2002

19. ‘On’ example: convergence Fig. 11-24 Randall et al. 2002 Fig. 11-23 Randall et al. 2002 (11-23)

20. Integrate information from many simple cells… Can detect movement orientation... (11-25) Fig. 11-25 Randall et al. 2002

21. Process and Respond… (11-17) Fig. 11-17 Randall et al. 2002 Fig. 11-22 Randall et al. 2002 (11-22)

22. Cortical Maps Fig. 11-27 Randall et al. 2002 One eye into monkey visual cortex (11-27)

23. Behavioral Examples Echolocation in bats - High frequency sound pulses - Large auditory center in brain - Sound pulse as energetic as jet 100m overhead or 20x jackhammer - Sensitive auditory ossicles (desensitized briefly as sound pulse emitted) (11-9) Fig. 11-9 Randall et al. 2002 - Sound intensity drops as square of distance; return signal weak (tonotopic maps in space)

24. Behavioral Examples Navigation via Magnetic Fields • Pelagic Whales • Homing Pigeons • Cave salamanders • Bacteria etc. - often a redundant system - Magnetite particles (Fe3O4) orient with magnetic field - Receptors detect -> processed in CNS

25. CPG = central pattern generator -neuronal network producing repetitive output Walking, swimming, flying, breathing Toad walking with no afferents - awkward - flaccid muscles Sensory feedback Higher centers can override Some patterns at level of spinal cord if stimulate initially (cats on treadmill)

26. End