# Presentation: 017561

## Varieties of Impulsivity: Evidence from Animal Studies

- John Evenden
- Dept of Neurosciences
- AstraZeneca R & D Wilmington
- Wilmington, DE, USA

## What’s in this talk

**Four Questions**
- What is Meant by Different Varieties of Impulsivity?
- Do Biologically Important Factors Influence the Different Varieties of Impulsivity in Different Ways?
- How does “personality”  (or trait impulsivity) interact with state impulsivity?
- Does it make a difference whether impulsive behaviour leads to loss of rewards or  punishment?

## Question 1What is Meant by Different Varieties of Impulsivity?

## Slide 4

## Impulsive Decision Making and the 3-term Contingency

## Three types of impulsive decision making

**PREPARATION**	**Not all relevant information**	Uncertain
- 			     	**is taken into account before****     **Discrimination
- 			           **making a decision**
**EXECUTION**		**The necessary behaviour is**** **	Fixed Consecutive
- 			     	**ended before the goal is****	****     ****	**Number Test
**	****	****	****	****attained**
**CONSEQUENCES**** **  **A quick, but less valuable****     ****	**Delayed
**	****	****	****	****outcome is chosen rather **	Reinforcement Test
- 		 		**than a later but more valuable****	**

## Three tests of impulsive decision making

**PREPARATION**	Not all relevant information	**Uncertain**
- 			     	is taken into account before**     ****	****Discrimination**
- 			           making a decision
**EXECUTION**		The necessary behaviour is** **	**Fixed Consecutive**
- 			     	ended before the goal is	**     ****	****Number Test**
**	****	****	****	**attained
**CONSEQUENCES**** **  A quick, but less valuable**     ****	****Delayed**
**	****	****	****	**outcome is chosen rather** **		**Reinforcement Test**
- 		 		than a later but more valuable**	**

## Question 2Do Biologically Important Factors Influence the Different Varieties of Impulsivity in Different Ways?

## Fixed Consecutive Number Schedule

- L.L.L.R        	         = 3   No Food
- L.L.L.L.L.L.L.R	         = 7   No Food
- L.L.L.L.L.L.L.L.R        = 8   Food
- L.L.L.L.L.L.L.L.L.L.R = 10   Food
- Count up how many times
- each length occurs and plot it
- in a histogram (distribution
- analysis)

## Paced Fixed Consecutive Number Test

- Trained to press left and right lever to obtain small food pellets
- After this the levers are retracted for either 2 or 5 seconds
- 	every time the rats presses
- Trained press first the left lever then the right lever to get
- 	food
- Trained to press the left lever several times before pressing
-  	the right lever to get food.
- This way the experimenter has control over how fast the
- 	rat can press the lever and the minimum time to complete a chain of responses

## Paced Fixed Consecutive Number Schedule 

- Paced Fixed Consecutive Number Schedule
- 		- 8-OH-DPAT, DOI - survival plot

- 8-OH-DPAT reduces impulsivity, DOI increases impulsivity

## Uncertain Discrimination

- Rats are first trained that a lit lamp
- signals lever which gives food
- When they have been trained to  95 - 100% correct
- the test procedure is started in which the signal
- is made uncertain.
- First one of the levers is chosen as “correct”.
- Then one of the three lights is turned on at random.
- After 0.1 s that light is turned of, and again one of the
-   lights is turned on at random
- ...and so on...
- Each time one of the lights is chosen, the probability that it is the one over the correct lever
- increases by a small amount until after about 5 s it is on nearly all the time.

- Lamps

## Uncertain Discrimination - 8-OH-DPAT, DOI

## Impulsivity - Trait and State

- We usually think of impulsivity as an aspect of personality
-    DSM personality disorders are essentially lifelong
-    Most personality questionnaires are designed to look for the personality trait of impulsivity
- But
-    Drugs change the state of the subject, not his/her underlying personality

## Question 3How does “personality”  (or trait impulsivity) interact with state impulsivity? 

## State and Trait interactions

- Acutely administered drugs are a model of “state”
- Different strains of rats are models of different patterns of “traits”
- Question
- Do the drugs have the same effects in different rat strains with different levels of “trait impulsivity”?

## Paced Fixed Consecutive Number Schedule      - amphetamine, haloperidol - AA/ANA rats

## Question 4Does it make a difference whether impulsive behaviour leads to loss of rewards or threat of punishment?

## Motivation and impulsivity

- Most non-human impulsive behaviour results in loss of positive reinforcers
- Much human impulsive behaviour results in delivery of punishers
- Question
- Is it possible to model self control using avoidance of punishment in rats?

## Fixed Consecutive Number Shock Avoidance

- Basic schedule is two-lever paced fixed consecutive number (FCN6)
- Option 1: make 6 or more consecutive responses on left lever and then press right lever for delivery of one food pellet
- Option 2: make less than 6 consecutive responses on left lever and then press right lever for delivery of one food pellet + 0.5s footshock (0.45 - 0.9 mA)

## Paced FCN Shock Avoidance

- Amphetamine increases impulsivity if the outcome is loss of reward, but reduces impulsivity is the outcome is punishment

## Summary

- Different aspects of impulsivity are differentially sensitive to the various drugs
- dopaminergic drugs primarily seem to affect EXECUTION of behaviour
- “traditional” serotonergic deficit may fit best with a deficit in PREPARATION
- Effects of the drugs don’t always fit with expectations
- The effects of the drugs depend (in part) on the strain of rat used.  Impulsive behaviour is modulated by trait factors (genetics, “personality”), and state factors (in this case, drug treatment).   These factors interact with one another. This interaction is complex and not obvious
- Positive reinforcement schedule and punishment schedule can maintain the same pattern of self control/impulsivity
- The effects of drugs can be dramatically different if self-control is brought about by negative reinforcement (loss of reward) or punishment.