Biology 484 Ethology Topic 5 Neural Mechanisms Controlling

Biology 484 – Ethology Topic 5 – Neural Mechanisms Controlling Behavior

Chapter 4 Woodhouse’s toad What guides the behavior of these toads in mating? The Nervous System

4. 1 A complex response to simple stimuli The male in “B” is attempting to mate with the thumb of the author of our book. The releaser of the behaviors for mating appear in this species to be a result of tactile stimulation on the undersurface of the insect. The shape of the female is roughly the same as the shape of the person’s thumb.

4. 2 A simple rule of thumb governs this beetle’s mating behavior Colletes hederae displaying mating frenzy. The male can develop this “mating frenzy” under a wide array of conditions, all related to stimulation of the undersurface of the body. Here see a cluster of blister beetle larvae which the bee will also attempt to mate with, with surprising results.

4. 3 Pioneers in the study of animal behavior Tinbergen Lorenz von Frisch

4. 4 Begging behavior by a gull chick The gull chick can elicit food regurgitation in the parent by tapping on the parent’s beak. The tapping behavior by the chick is neurally controlled as is the sensory detection of the tapping by the parent.

4. 5 Effectiveness of different visual stimuli in triggering the begging behavior of herring gull chicks In this graph, we can see the components examined thought to be responsible for the elicitation of the pecking behavior in the chick. Note the numbers are relative percentages in each example.

4. 6 Instinct theory Tinbergen originated the INSTINCT THEORY along with Lorenz. The basics of theory are that simple stimuli (such as the red dot) can “release” a complex behavior in another bird such as the chick’s tapping behavior (begging behavior).

4. 7 A code breaker The cuckoo in this image has been able to figure out the necessary behavioral pattern to guide the parent bird ( a reed warbler ) to give it food. In effect, the cuckoo has learned to be a behavioral code breaker.

The male Australian Beetle will attempt to mate with virtually anything that is of a similar color to itself. On the left is a beer bottle, on the right a road sign. Thought Question: This behavior seems to be not appropriate, how/why would you hypothesize the behavior remains in the species?

Santiago Ramon Y. Cajal (1852 -1934) Founding Scientist in the Modern Approach to Neuroscience. Received Nobel Prize in 1906

Figure 11. 3: Neuroglia, p. 390. Capillary Neuron (b) Microglial cell (a) Astrocyte Nerve fibers Myelin sheath Fluid-filled cavity Process of oligodendrocyte (c) Ependymal cells Schwann cells (forming myelin sheath) Brain or spinal cord tissue Cell body of neuron Satellite cells (d) Oligodendrocyte Nerve fiber (e) Sensory neuron with Schwann cells and satellite cells Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 5: Relationship of Schwann cells to axons in the PNS, p. 394. Schwann cell cytoplasm Axon Schwann cell plasma membrane Schwann cell nucleus Myelin sheath (a) Schwann cell cytoplasm Axon Neurilemma (b) (d) Neurilemma Myelin sheath (c) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Neurotransmitter chemical attached to receptor Receptor Na+ Chemical binds K+ K+ Closed Open (a) Chemically gated ion channel Na+ Membrane voltage changes Closed Open (b) Voltage-gated ion channel Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 7: Measuring membrane potential in neurons, p. 399. Voltmeter Plasma membrane Ground electrode outside cell Microelectrode inside cell Axon Neuron Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Cell interior sion Na. D+ ifuf usio Diff K+ + Cell interior Na 15 m. MK+ -70 150 m. M Cl– m. V – Na+ 10 m. M A 100 m. M 150 m. M – A + 0. 2 m. M K Cl– 5 m. M 120 m. M Cell exterior n Figure 11. 8: The basis of the resting membrane potential, p. 399. K+ K+ Cell Na+ exterior + Na+Na Na+ Na+–K+ pump Plasma membrane K+ K+ Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 9: Depolarization and hyperpolarization of the membrane, p. 400. Depolarizing stimulus Hyperpolarizing stimulus +50 Inside positive 0 Inside negative Depolarization – 50 – 70 Resting potential – 100 0 1 2 3 4 5 6 Membrane potential (voltage, m. V) +50 7 Time (ms) (a) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn 0 – 50 Resting potential – 70 – 100 Hyperpolarization 0 1 2 3 4 5 6 7 Time (ms) (b) Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 10: The mechanism of a graded potential, p. 401. Depolarized region Stimulus Plasma membrane (a) Depolarization Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn (b) Spread of depolarization Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Membrane potential (m. V) Figure 11. 11: Changes in membrane potential produced by a depolarizing graded potential, p. 402. Active area (site of initial depolarization) – 70 Resting potential Distance (a few mm) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Inside cell K+ 2 Depolarizing phase: Na+ channels open Inside K+ cell Repolarizing phase: Na+ channels inactivating, K+ channels open Relative membrane permeability Outside Na+ cell Membrane potential (m. V) Outside. Na+ cell Action potential +30 3 0 2 PNa PK Figure 11. 12: Phases of the action potential and the role of. Threshold voltage-gated ion channels, p. 403. 0 1 4 1 2 3 Time (ms) 4 Outside cell Sodium Potassium + Na channel Outside + Na cell Activation. K+ gates Inactivation gate 1 Resting state: All gated Na+ and K+ channels closed (Na+ activation gates closed; inactivation gates open) Inside K+ cell 4 Hyperpolarization: K+ channels remain open; Na+ channels resetting Inside cell Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn – 55 1 – 70 Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Membrane potential (m. V)) Figure 11. 13: Propagation of an action potential (AP), p. 405. Voltage at 2 ms +30 Voltage at 0 ms Voltage at 4 ms – 70 (a) Time = 0 ms (b) Time = 2 ms (c) Time = 4 ms Resting potential Peak of action potential Hyperpolarization Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Voltage Membrane potential (m. V) Figure 11. 14: Relationship between stimulus strength and action potential frequency, p. 406. Action potentials +30 – 70 Threshold Stimulus amplitude 0 Time (ms) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 15: Refractory periods in an AP, p. 406. Absolute refractory period Membrane potential (m. V) +30 Relative refractory period Depolarization (Na+ enters) 0 Repolarization (K+ leaves) After-hyperpolarization – 70 Stimulus 0 1 2 3 4 5 Time (ms) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 16: Saltatory conduction in a myelinated axon, p. 407. Node of Ranvier Cell body Myelin sheath Distal axon Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 17: Synapses, p. 409. Cell body Dendrites Axodendritic synapses Axosomatic synapses Axoaxonic synapses Axon (a) Axon Axosomatic synapses (b) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Soma of postsynaptic neuron Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

Figure 11. 18: Events at a chemical synapse in response to depolarization, p. 410. on ti Ac Neurotransmitter Receptor Ca 2+ ten Po 1 l tia Axon of presynaptic neuron Synaptic vesicles containing neurotransmitter molecules Synaptic cleft Ion channel (closed) Human Anatomy and Physiology, 7 e by Elaine Marieb & Katja Hoehn Axon terminal of presynaptic neuron Postsynaptic Mitochondrion membrane Postsynaptic membrane Ion channel open 5 Degraded neurotransmitter 2 3 Na+ 4 Ion channel (open) Ion channel closed Copyright © 2007 Pearson Education, Inc. , publishing as Benjamin Cummings.

4. 10 The eyestalks of a fiddler crab point straight up The eyestalks in this crab point upwards and determine its field of view. The stalks will change the perspective it views compared to other many other more standard positions. Question to Ponder…. What can you hypothesize about the role/benefit for this placement for the crab compared to other eye positions?