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Sensory Guidance and

Oriented Behavior

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Lecture 40

BioNB4240

W41

1) Spend 4 hours normally devoted to writing assignment on your Wikipedia project

2) Put your notes and outlines and sources down in outline form as far as you have yprogressed

3) Print and hand in class Monday

4) Your assignment grade (0-10) will be based on subjective estimate of progress made so far.

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Sensory Guidance and Oriented BehaviorHow organisms respond to external

stimuli:– ORIENTATION: turning response, or oriented

response guided by stimulus location or direction.

RESPONSE SELECTION: choice of response

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– RESPONSE SELECTION: choice of response behavior as appropriate to stimulus.

– Nearly every behavior has a component to it that involves orientation.

Examples of Oriented Behavior

• Chemotaxis

• Chemical trail following

• Directional tactile sense

• Sensing compass directions

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• Sensing compass directions

• Using landmarks and memory

How do organisms sense the direction of a stimulus?

by detecting the incident direction of the stimulus using an array of detectors

by measure of stimulus gradient with two simultaneous sensors

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by comparing two sensors

by successive comparison of a single comparison in time

with a single sensor compared successively in time.

Collective behavior of bacteria around a food source

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Bacterial Chemotaxis

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no attractantcell tumbles

attractantcell runs

Taxes

Orientation relative to a stimulus direction

Phototaxis: orientation toward the light

Negative phototaxis: orientation away from the light

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orientation of a planaria

primitive photoreceptors providessome directional cue

Trail following in an ant

normal trail following

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one antenna, one removed.

antennae crossed

Snake (Vipera aspis) path of head movements tracks the pathway left by a mouse, recently dead by snake bite

Olfactory orientation to prey by a snake

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recently dead by snake bite, which has been dragged across the 1x1 m arena. Dotted line: path of live mouse. Circle (hiding place of mouse).

Pheromone Sensing in Moths

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Paramecium has a directional tactile sense

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paramecium avoids contact byreversing direction of swimming

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Electrophysiology of Paramecium

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microelectrode recording

anterior stimulationposterior stimulation

anterior: depolarize Ca++

posterior: hyperpolarize K+

From studies by R. Eckert

Orientation to Vibration Sources

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Jaques Loeb’s Model for Taxes

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Loeb (1918) Mechanistic approach to animal orientation: taxes and kineses.

Applies to numerous cases of sensory guidance: light, heat, odor, sound, gravity, electroreception.

Using the sun to orient flight

informing danceis performed in the hive

the sun is used as the‘landmark’

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food is located at a distance from hive the direction of the dance corresponds

to the direction of food relative to thatof the sun. Gravity is substituted reference.

Orientation in Digger Wasps(Tinbergen and Kruyt, 1938)

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Digger wasp leaves nest and circles opening for 6 second. Pine cones are placed there during time when she is belowground

Female returns to provide food. Pine cones have been moved.

Thus, behavior is guided by learning.

Special Senses

Insect eye: sensitive to polarized light.

Pigment molecules are embedded in membrane at random

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membrane at random.

Membranes are organized into structured microvilli.

Orientation of pigment in rhabdome now has a preferred alignment relative edge of microvilli.

Senses polarized light.

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Vertebrate Rod

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R. Wehnerpolarized light sensitive area of honey bee is essential to orientation to the sun’s compass.

Ommatidia in dorsal POL are sensitive to UV light.

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The rhabdom does not twist in this area (so the plane of the microvilli are aligned only in one direction) area retain polarization sensitivity.

Other areas: twist destroys polarization sensitivity

Orientation in the desert ant, Cataglyphis bicolor

Use of sun depends upon polarized light sensitivity in UV.

Eye is organized to match the pattern of sky polarization Ant

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pattern of sky polarization. Ant gets intensity readout which is directionally sensitive.

Land and Collett (1974):

Visual chasing in flies

A classic paper in neuroethology.

Demonstrates visual guidance is controlled by angular position of target

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angular position of target, and by angular velocity of target across the retina.

Demonstrates that males have “fovea” dorsal region of high velocity and temporal resolution.

How do electric fish locate sources?

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Schluger and Hopkins (1986)26

Schluger and Hopkins (1986)