HOMEWORK

1. The insular cortex is thought to be      involved in compassion and empathy, taste, perception, motor control,      self-awareness, cognitive functioning, and interpersonal experience. In      this paper, the focus is its role in substance abuse. Which of these is not mentioned by the authors in explaining      the link between the insular cortex and drug-seeking behaviors?

lesions in the   insular cortex interrupt drug-seeking behaviors

individuals with   substance abuse history showed reduced activity in the insular cortex 

there are no   drug-related receptors in the insular cortex

the anterior   agranular insula subregion contains dopamine and opioid receptors

10 points   

QUESTION 2

1. The authors used 35 day      old rats because

35 days is   adolescent, when initial drug exposure occurs often in humans

35 days corresponds   to the age at which rats in the wild begin buying drugs

Rats do not develop   an insular cortex until 30 days

The rat brain has   no insular cortex so it doesn’t matter

10 points   

QUESTION 3

1. How did limited and      extended  intravenous self-administration training differ?

10 points   

QUESTION 4

1. Did pressing the lever      during a test result in a predictable delivery of cocaine or an      unpredictable dose? Why do you think it was done this way?

10 points   

QUESTION 5

1. Did cocaine-seeking      behaviors increase or decrease on withdrawal day 45, relative to      withdrawal day 1? Did this effect depend on the amount or duration of      prior cocaine use (that is, limited or extended)?

10 points   

QUESTION 6

1. An action potential      occurs when the membrane potential of a specific cell location rapidly      rises and falls; this is an essential part of neuron signaling.
   
   
        What is meant by  rise time, decay time, half‐amplitude duration ,      and amplitude of action potentials?
   
    

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10 points   

QUESTION 7

1. How are the rise time,      decay time, half‐amplitude duration, and amplitude of action potentials in      pyramidal neurons of the insular cortex affected by cocaine training?

10 points   

QUESTION 8

1. When a depolarizing      current is injected into a nerve cell, the resultant decrease in the      membrane potential activates voltage-dependent Na+ channels. The      activation of the Na+ channels in turn accelerates the depolarization      process, producing the rising phase of the action potential.
        This causes the neuron to fire, or spike.
   
        Injecting depolarizing current is done to assess whether the sensitivity      of a neuron is changed by a procedure (which would be measurable as a      change in the spike rate of the neuron).
   
        In this paper, would you say that cocaine administration was shown to      alter the sensitivity of insula pyramidal neurons to stimulation? Why or      why not?

10 points   

QUESTION 9

1. For any given neuron,      there is also a threshold of action potential. What does that mean?
2. Is the action potential      threshold shown to be changed by limited or extended cocaine training? How      do you know this?

10 points   

QUESTION 11

1. It is generally thought      that extended drug exposure has more robust effects on drug‐seeking and      drug‐taking behaviors than limited use. Does this study support or      contradict this bit of conventional wisdom? How?

10 points   

QUESTION 12

1. In this model, rats      learn that pressing a lever is rewarded with an injection of cocaine.      However, some rats with a history of extended training seem not to press      the lever. What might explain this?

10 points   

QUESTION 13

1. What is the main      difference (as the authors describe it) between the methods of this study      and those of other rat cocaine studies?