Biology 484 – Ethology
Chapter 4a – 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 the 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 toNeuroscience. Received Nobel Prize in 1906
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.3: Neuroglia, p. 390.
(a) Astrocyte
(d) Oligodendrocyte
(e) Sensory neuron with Schwann cells and satellite cells
(b) Microglial cell
(c) Ependymal cells
Schwann cells(forming myelin sheath)
Cell bodyof neuronSatellite cells
Nerve fiber
Capillary
Neuron
Nerve fibers
Myelin sheath
Process ofoligodendrocyte
Fluid-filled cavity
Brain or spinal cord tissue
Human Anatomy and Physiology, 7eby 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.
(a)
(b)
(c)
(d)
Schwann cellcytoplasm
Axon
NeurilemmaMyelinsheath
Schwann cellnucleus
Schwanncell plasmamembrane
Myelin sheath
Schwann cellcytoplasm
Neurilemma
Axon
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
(a) Chemically gated ion channel
Na+
K+K+
Na+
(b) Voltage-gated ion channel
Na+Na+
Receptor
Neurotransmitter chemical attached to receptor
Closed Open
Membranevoltagechanges
Closed Open
Chemicalbinds
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.7: Measuring membrane potential in neurons, p. 399.
Voltmeter
Microelectrodeinside cell
Plasmamembrane
Ground electrodeoutside cell
Neuron
Axon
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.8: The basis of the resting membrane potential, p. 399.
Na+Na+
K+K+
K+
K+
Na+
Na+
Na+
Na+
Cell interior Na+
15 mMK+
150 mMCl–
10 mMA–
100 mMNa+
150 mMA–
0.2 mMCell exterior
K+
5 mM Cl–
120 mM
Cellexterior
Cellinterior
Plasmamembrane
Na+–K+
pumpDiffu
sion
K+ Na+ D
iffusio
n
-70 mV
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.9: Depolarization and hyperpolarization of the membrane, p. 400.
Depolarizing stimulus
Mem
bran
e po
tent
ial (
volta
ge, m
V)
Time (ms)
0–100
–70
0
–50 –50
+50
1 2 3 4 5 6 7
Hyperpolarizing stimulus
Mem
bran
e po
tent
ial (
volta
ge, m
V)
Time (ms)
0 1 2 3 4 5 6 7–100
–70
0
+50
Insidepositive
Insidenegative
(a) (b)
Restingpotential
Depolarization Restingpotential
Hyper-polarization
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.10: The mechanism of a graded potential, p. 401.
(b)
Depolarized region Stimulus
Plasmamembrane
Depolarization Spread of depolarization(a)
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.11: Changes in membrane potential produced by a depolarizing graded potential, p. 402.
Distance (a few mm)
–70Resting potential
Active area(site of initialdepolarization)
Mem
bran
e po
tent
ial (
mV)
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.12: Phases of the action potential and the role of voltage-gated ion channels, p. 403.
0 1 2 3 4–70–55
0
+30
Mem
bran
e po
tent
ial (
mV)
Time (ms)
Rel
ativ
e m
embr
ane
perm
eabi
lity
Na+Na+
K+K+
Outsidecell
Insidecell
Outsidecell
Insidecell
Depolarizing phase: Na+
channels openRepolarizing phase: Na+
channels inactivating, K+
channels open
Action potential
PNa
PK Threshold
Na+Na+
K+K+
Outside cell
Insidecell
Outsidecell
Insidecell
Inactivation gate
Activationgates
Potassiumchannel
Sodiumchannel
Resting state: All gated Na+
and K+ channels closed (Na+ activation gates closed; inactivation gates open)
Hyperpolarization: K+
channels remain open; Na+ channels resetting
2
2
3
4
4
1
11
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.13: Propagation of an action potential (AP), p. 405.
–70
+30
(a) Time = 0 ms (b) Time = 2 ms (c) Time = 4 ms
Voltageat 2 ms
Voltageat 4 ms
Voltageat 0 ms
Resting potentialPeak of action potentialHyperpolarization
Mem
bran
e po
tent
ial (
mV)
)
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.14: Relationship between stimulus strength and action potential frequency, p. 406.
Time (ms)
Volta
geM
embr
ane
pote
ntia
l (m
V)
–70
0
+30
Threshold
Actionpotentials
Stimulusamplitude
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.15: Refractory periods in an AP, p. 406.
Stimulus
Mem
bran
e po
tent
ial (
mV)
Time (ms)
–70
0
+30
0 1 2 3 4 5
Absolute refractoryperiod
Relative refractoryperiod
Depolarization(Na+ enters)
Repolarization(K+ leaves)
After-hyperpolarization
Human Anatomy and Physiology, 7eby 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 Myelinsheath
Distalaxon
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.17: Synapses, p. 409.
(a)
(b)
Cell body
Dendrites
Axon
Axodendriticsynapses
Axoaxonicsynapses
Axosomaticsynapses
Axosomaticsynapses
Soma of postsynaptic neuron
Axon
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 11.18: Events at a chemical synapse in response to depolarization, p. 410.
Synaptic vesiclescontaining neurotransmitter molecules
Axon of presynapticneuron
Synapticcleft
Ion channel(closed)
Ion channel (open)
Axon terminal of presynaptic neuron
PostsynapticmembraneMitochondrion
Ion channel closed
Ion channel open
NeurotransmitterReceptor
Postsynapticmembrane
Degradedneurotransmitter
Na+
Na+
Ca2+
Action Potential
1
2
3 4
5
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?
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