Lecture 18 - Motivation

Question 1

Motivation

Answer 1

construct used to explain variability and flexibility in behavior output attributable to external stimuli and internal states

• appetitively motivated behaviors: goal of attaining psoitive objects or envi consequences (food, water, sex)
• aversively motivated behaviors: prevent/terminate negative stimuli

Question 2

Basal ganglia circuitry

Answer 2

input from cortical mantle –> striatum –> palladium –> thalamic
-indirect vs. direct pathway

Question 3

Nucleus accumbens

Answer 3

ventral, medial, anterior aspect of basal ganglia

• part of the “limbic” CSPT circuit
• innervated by ascending dopamine pathways
• medium-spiny neurons receive NT signal and integrate multiple complex neurochemically specified inputs

Question 4

Dopamine

Answer 4

modulates glutamate signals at spiny neurons

Question 5

CPST loop

Answer 5

prefrontal cortex/amygdala/hippocampus –> nucleus accumbens –> ventral pallidum –> MD thalamus –> cortical motor-planning regions

• parallel loops from distict cortical areas
• palladial level of BG also outputs directly to brainstem
• specialized for motivationally relevant info

Question 6

Ventral tegmental

Answer 6

strongest self-stimulation behavior

• input to hippocampus
• dopamine-rich = reward

Question 7

“wanting”

Answer 7

dopamine regulated
-identify salient reinforcers and pursue them
-go after something
-important for learning about rewards:
> The 1st time experiencing new reward
> observing stimuli that reliably predicts award ***
> when previous reward is better than predicted
-dopamine firing early in training is direct response to reward
-dopamine firing later in training associated with stimulus that predicts reward

Question 8

“liking”

Answer 8

opioid regulated

-subjective emotional experience of pleasure upon interacting with reinforcer

Question 9

Tolerance

Answer 9

progressively diminished phys response to drug with repeated exposure (right shift of dose-effect fx)
-opposite: sensitization

Question 10

Dependence

Answer 10

phys state induced by repeated exposure to drug where drug presence is necessary for normal function

Question 11

Craving

Answer 11

subjective state of intense desire for particular goal

Question 12

Addiction

Answer 12

• loss of control over limiting intake
• habit persists despite negative consequences
• narrowing of other activities
• potential for relapse throughout life-span

Question 13

Withdrawal

Answer 13

homeostatic adaptation to drug = tolerance, and absence of drug = withdrawal
-expressed as physical symptoms or psychological symptoms
Opponent process theory
-rush/euphoria peak gets smaller over time due to adaptation, as does peak of withdrawal (gets worse)

Question 14

Incentive-sensitization hypothesis

Answer 14

learning-based theory of addiction

-drug use leads to long-lasting sensitization of dopamine’s ability to produce drug “wanting”

Question 15

Reward-error prediction hypothesis

Answer 15

learning-based theory of addiction
-enhanced dopamine release during drug taking produces a condition in which ALL stimuli encountered during drug use are experienced as being “better than expected”

Question 16

Impulsive behavior and addiction

Answer 16

2 relevant features:

1. tendency to consistently choose immediate reinforcement over delayed gratification, even when immediate reinforcement is smaller or less beneficial
2. impairment in ability to inhibit a course of action once initiated
   - excessive “wanting” of drugs or drug-related stimuli, such that inhibitory control is overwhelmed
   - impaired PFC function (nucleus accumbens gets input from PFC –> controls impulsivity, so if compromised lose inhibitory control so abnormal accumbens fx)

Question 17

Compulsive behavior and addiction

Answer 17

repeat/prolong certain behavior strategy even in face of unsuccessful or adverse outcomes

• in addiction, individuals often report “wanting’ the drug more even though they “like” it less. They also “want” the drug despite adverse outcomes
• shift from prefrontal-accumbens motor circuits to emphasis on dorsal striatal control
• dorsal striatum mediates compulsive “habits”

Question 18

Addiction cycle

Answer 18

1. preoccupation/anticipation
   –> (persistent desire, larger amounts taken than expected) 2. binge/intoxication
   –> (tolerance, withdrawal, compromised social, occupational or recreational activities)
2. withdrawal/negative affect
   –> preoccupation with obtaining, persistent physical/psych problems
   back to 1.