biology 484 – ethology chapter 4a – neural mechanisms controlling behavior

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 neuron

Satellite 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 mM

Cell exterior

K+

5 mMCl–

120 mM

Cellexterior

Cellinterior

Plasmamembrane

Na+–K+

pumpDif

fusi

on

K+ Na

+ Diffu

sion

-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

bra

ne

po

ten

tial

(vo

ltag

e, m

V)

Time (ms)

0–100

–70

0

–50 –50

+50

1 2 3 4 5 6 7

Hyperpolarizing stimulus

Mem

bra

ne

po

ten

tial

(vo

ltag

e, m

V)

Time (ms)

0 1 2 3 4 5 6 7–100

–70

0

+50

Insidepositive

Insidenegative

(a) (b)

Restingpotential

DepolarizationRestingpotential

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

bra

ne

po

ten

tial

(m

V)

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

Me

mb

ran

e p

ote

nti

al

(mV

)

Time (ms)

Re

lati

ve

me

mb

ran

e

pe

rme

ab

ilit

y

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 potential

Peak of action potential

Hyperpolarization

Me

mb

ran

e p

ote

nti

al

(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)

Vo

ltag

eM

emb

ran

e p

ote

nti

al (

mV

)

–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

bra

ne

po

ten

tial

(m

V)

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 bodyMyelinsheath

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

Postsynapticmembrane

Mitochondrion

Ion channel closed

Ion channel open

Neurotransmitter

Receptor

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?