Chapter 9 - Neuromodulation: The accommodation of motivational changes in behavior

Question 1

Motivation

Answer 1

The physiological state of an animal which defines the frequency and intensity of occurrence of a behavior when elicited by a given endogenous or exogenous stimulus

Question 2

Motivational changes in behavior are possible only…

Answer 2

In networks exhibiting the potential for neural plasticity

Question 3

Two major neural mechanisms that mediate motivational changes in behavior

Answer 3

• Structural reorganization of networks
• Biochemical switching of neural networks

Question 4

Chirps

Answer 4

• Transient frequency and amplitude modulation of the electric organ discharge
• Are controlled by a subnucleus of the central posterior/prepacemaker nucleus in the dorsal thalamus
  – Determined using retrograde tracer staining placed in pacemaker nucleus which traced to central posterior/prepacemaker nucleus
• Plays role in courtship and aggression

Question 5

Glass knifefish

Answer 5

Can produce chirps

Question 6

Seasonally induced changes in chirping behavior are accompanied by…

Answer 6

• Alterations in dendritic morphology of central posterior/prepacemaker nucleus neurons
  – Dendrites grow out during rainy season for mating, then retract

Question 7

Cyclical sexual maturity

Answer 7

• Occurs each rainy season
• Seasonal cycling of sexual maturity/immaturity (physiological changes)

Question 8

Spinal nucleus of the bulbocavernosus in white-footed mouse

Answer 8

• Located in lumber region of spinal cord (lower region)
• 200 (60) motoneurons in males (females)
• In males, the majority of motoneurons innervate muscles bulbocavernosus and levator ani
• Attached to base of penis (erection and ejaculation)
• Critical for controlling sexual behavior in males
• In spring increased testosterone leads to increased number of axon projections and in winter less testosterone leads to fewer axon projections
  – Can mimic sexual immaturity with castrated mouse

Question 9

Stomatogastric nervous system in spiny lobster

Answer 9

• A single stomatogastric ganglion
• A single oesophageal ganglion
• Bilaterally paired commissural ganglia
• The stomatogastric nerve

Question 10

The stomatogastric ganglion of decapod crustaceans consists of…

Answer 10

26-30 individually identified neurons that control rhythmic movements of the foregut

Question 11

The muscles innervated by the stomatogastric ganglion neurons move different regions of the foregut

Answer 11

• Gastric mill
  – Consists of three teeth
  – Rhythmic movements of the gastric mill muscles (gastric mill rhythm)
• Pylorus
  – Abuts the gastric mill region
  – Filtering and sorting movements that control both the pylorus and its valves (pyloric rhythm)

Question 12

Input to the stomatogastric ganglion, originating from somata of the commissural ganglia and the oesophageal ganglion, as well as from gastropyloric receptor neurons, contains…

Answer 12

A large number of neuromodulators

Question 13

Polymorphic networks

Answer 13

Anatomically defined networks whose modulation results in multiple functional modes of operation

Question 14

Large dense-core vesicles

Answer 14

• 70-200 nm
• neuroactive peptides, growth factors, amines, hormones
• synthesized in cell body
• transported
• not recycled
• variable numbers, usually fewer than synaptic vesicles
• located distant from active zone
• trains of action potentials to release
• slow, diffuse, neuromodulatory

Question 15

Administration of serotonin to the hemolymph of subordinate crayfish can…

Answer 15

Change the aggressive motivation toward higher levels

Question 16

The modulatory effect of serotonin on the lateral giant interneuron (a command neuron controlling escape) is itself modulated by the social status and the social history of the crayfish

Answer 16

• Dominant crayfish
  – The response of the lateral giant interneurons triggered by serotonin is transiently increased
• Subordinate crayfish
  – The response of the lateral giant interneurons triggered by serotonin is transiently inhibited