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Evolution, Nervous Systems, and BehaviorChapter 12
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1-Stimuli detected2-Response generatedWhat is the purpose?
Simple Reflex
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Neuron Anatomy
Dendrites, cell body, axon
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Vesicular Synapse1.Action Potential
2. Neurotransmitter
is released
3. Binds to next cell
4. New action
potential is created.
https://www.hhmi.org/biointeractive/molecular-mechanism-synaptic-function
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Stimulus travels in by sensory neuronResponse travels out by
motor neuronThere may be an interneuron between
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The interneuron allows integration in the central nervous
system.Peripheral nervous system vs. Central n.s.
When would you “want” integration?
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Summary of stimulus-response
Brain
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Simple stimuli leads to complex behaviorAn FAPN. Tinbergen:
Herring Gull begging
behaviorhttp://www.sumanasinc.com/webcontent/animations/content/fixedbehavior.html
http://www.sumanasinc.com/webcontent/animations/content/fixedbehavior.html
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Consider the visual stimuli
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What is the primary stimulus?
What is the response?
Releaser: the stimulus FAP: the complex response
See this with colors and mating behaviors….
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Bat hunting behaviorGriffin
Spallanzani: bats don't need to see
Jurine: bats need to hear
Hartridge: ultrasound
Griffin et al: echolocation
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Roeder: Moth Avoidance
https://www.youtube.com/watch?v=MgRh_Q_xwys
https://www.youtube.com/watch?v=O8psKvn0_3w
Insects that avoid bats include?
https://www.youtube.com/watch?v=MgRh_Q_xwyshttps://www.youtube.com/watch?v=O8psKvn0_3w
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Predator avoidance as a reflex
Stimuli?
Where is the receptor?
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Two Receptors: A1 and A2
Moth Avoidance Behavior
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A2 to highThese 2 receptors allow evasive responses
A1 responds to low intensity,
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Increased complexity of sound response
Observations:
1. crickets fly
2. crickets sing to attract mates at lower
frequency
3. crickets are prey for bats who call at
higher frequency
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Increased Complexity
Phonotaxis, what is it?
Predictions: ?
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Increased Complexity
How do you measure phonotaxis?
How does the insect determine
direction?
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If Interneuron-1 is stimulated?
Insect moves away from stimulus
Cannot show negative phonotaxis
without this interneuron
Arms Race!
Stimulus synapses with Interneuron-1
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What about positive phonotaxis?
Females approach…males also approach.
Additional neurons seem responsible for
positive movement.
What stimulus suppresses Interneuron-1?
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Unintended Consequences
Teleogryllus crickets
Ormia flies
Tuned to the cricket
frequency
Red
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Better images of cricket wings
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Other stimuli and nervous responses
Example: Visual stimuli: ultraviolet radiation and
signals
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Other escape mechanisms
Sea slug response to sea star
https://www.youtube.com/watch?v=onjZR4WZB8I
Stimuli?
Response?
Interneurons stimulate motor neurons- Central
Pattern Generator. Organizes the response.
https://www.youtube.com/watch?v=onjZR4WZB8I
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CNS: Brain AnatomyInterneurons in the brain- somatosensory
cortex
l Cerebral hemispheres
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Star-nosed MoleSensory cells, interneurons in the CNS
https://www.youtube.com/watch?v=fio1NUxszhY
https://www.youtube.com/watch?v=fio1NUxszhY
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Star-nosed Mole
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Cortical Maps
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Stimuli filtering at many levels
If there are more receptors, get more space in the cortex
What would a human look like?
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Cortical MapsWhere do we have lots of
receptors?
