Evolution, Nervous Systems, and BehaviorChapter 12
1-Stimuli detected2-Response generatedWhat is the purpose?
Simple Reflex
Neuron Anatomy
Dendrites, cell body, axon
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
Stimulus travels in by sensory neuronResponse travels out by motor neuronThere may be an interneuron between
The interneuron allows integration in the central nervous system.Peripheral nervous system vs. Central n.s.
When would you “want” integration?
Summary of stimulus-response
Brain
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
Consider the visual stimuli
What is the primary stimulus?
What is the response?
Releaser: the stimulus FAP: the complex response
See this with colors and mating behaviors….
Bat hunting behaviorGriffin
Spallanzani: bats don't need to see
Jurine: bats need to hear
Hartridge: ultrasound
Griffin et al: echolocation
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
Predator avoidance as a reflex
Stimuli?
Where is the receptor?
Two Receptors: A1 and A2
Moth Avoidance Behavior
A2 to highThese 2 receptors allow evasive responses
A1 responds to low intensity,
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
Increased Complexity
Phonotaxis, what is it?
Predictions: ?
Increased Complexity
How do you measure phonotaxis?
How does the insect determine
direction?
If Interneuron-1 is stimulated?
Insect moves away from stimulus
Cannot show negative phonotaxis
without this interneuron
Arms Race!
Stimulus synapses with Interneuron-1
What about positive phonotaxis?
Females approach…males also approach.
Additional neurons seem responsible for
positive movement.
What stimulus suppresses Interneuron-1?
Unintended Consequences
Teleogryllus crickets
Ormia flies
Tuned to the cricket
frequency
Red
Better images of cricket wings
Other stimuli and nervous responses
Example: Visual stimuli: ultraviolet radiation and
signals
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
CNS: Brain AnatomyInterneurons in the brain- somatosensory cortex
l Cerebral hemispheres
Star-nosed MoleSensory cells, interneurons in the CNS
https://www.youtube.com/watch?v=fio1NUxszhY
https://www.youtube.com/watch?v=fio1NUxszhY
Star-nosed Mole
Cortical Maps
Stimuli filtering at many levels
If there are more receptors, get more space in the cortex
What would a human look like?
Cortical MapsWhere do we have lots of
receptors?