Effects of Ethanol on Encoding and Retrieval

of Serial Rule Switch Operant TaskKristin S. Edwards and Ben Givens

Department of Psychology, The Ohio State University, Columbus, OH 43210 087-S-087

•Subjects: n= 5 adult male Long-Evans rats

•Operant Task Rule Contingencies: (See Figure 1)

• Delayed match to sample (DMTS)

• Delayed non-match to sample (DNMTS)

• Rules were counterbalanced across all switch

sessions

•Performance Criterion:

• >75% session accuracy for 3 sessions

•Single Rule Switch Model

• Day 1: Pre-Switch = Rule A

• Day 2: Injection 10 min before Switch = Rule B

• Day 3: Post Switch = Rule B

•Double Rule Switch Model

• Day 1: Pre Switch = Rule A

• Day 2: Injection 10 min before Switch = Rule B

• Day 3: Post Switch = Rule A

•Intraperitoneal Ethanol Injections:

• 10 minutes prior to rule switch

• 0.0, 0.25, 0.50, 0.75, or 1.0 g/kg ethanol (10% w/v)

•Data Analysis

• Repeated Measures ANOVA with 2 within-subjects

factors: Dosage (6 levels) x Time (3 levels)

Methods

Introduction

Results

Conclusions

Sample Phase

+5 Sec Delay

Delayed Match to

Sample (DMTS)

Delayed Non-Match to

Sample (DNMTS)OR

•The single switch paradigm produced a dose-

dependant impairment in memory encoding for task

rules demonstrated by decreased overall accuracy for

the post-switch session.

•The double switch paradigm showed that ethanol

produced a slight improvement in switch 2 performance

relative to controls suggesting less interference due to a

failure to encode the new contingency on switch 1.

•These results support the hypothesis that ethanol

disrupts memory encoding for task rules and these

effects are not due to a general cognitive impairment.

•Experiments are currently underway to use the serial

DMTS/DNMTS rule switch operant task paradigm as a

behavioral framework to study neurophysiological

mechanisms underlying the effects of ethanol on

memory encoding and retrieval.

Figure 1: Schematic Diagram of Operant Task Trial: In the sample

phase, 1 of 2 lights was randomly illuminated and required a correct lever

press to advance to a 5 sec delay period. When a tone sounded, either

the MTS or NMTS lever was rewarded (depending on the rule for the

day). The intertrial interval lasted 10 seconds, and a session continued for

90 minutes or 150 trials.

Figure 2: All rats showed similar high performance in the pre switch

session. In general, ethanol on a switch session dose–dependently

impaired accuracy on the post switch session. There were main effects of

Dosage (F (5, 20)=4.11, p=<.05) and Time (F (2, 8)=150.98, p<.05).

Asterisks indicate significant (p<.05) difference from no injection in paired

sample t –test of post switch time point.

Figure 3: When rats received ethanol on the switch day they

demonstrated slightly improved performance on the switch back to

the original rule. There were significant main effects of Dosage

(F (1,4) =11.50, p<.05) and Time (F (2, 8)=31.78, p<.05).

Acute exposure to low doses of ethanol is associated with

detrimental effects on various aspects of cognitive

functioning, including components of learning and memory

(White et al., 2000). Alcohol has differential effects on

encoding and retrieval depending on the memory task, the

type of memory involved, and the limb of the Blood

Alcohol Concentration (BAC) curve (Söderlund et al.,

2005). The main purpose of this study was to adapt a well-

validated operant conditioning behavioral task

(Dudchenko, 2004) into a serial rule-switching paradigm to

assess the effects of ethanol on memory encoding and

retrieval for task rules. We hypothesized that rats would be

able to learn task rules proficiently, perform multiple

switches between rule contingencies and that acute

exposure to low doses of ethanol would disrupt memory

encoding for new task rules.

References & AcknowledgmentsDudchenko, P. A. (2004). An overview of the tasks used to test working memory in rodents. Neuroscience and

Biobehavioral Reviews, 24, 699-709.

Söderlund, H., Parker, E. S., Schwartz, B. L., & Tulving, E. (2005). Memory encoding and retrieval on the ascending

and descending limbs of the blood alcohol concentration curve. Psychopharmacology, 182, 305-317.

White, A. M., Matthews, D. B., & Best, P. J. (2000). Ethanol, memory, and hippocampal function: A review of recent

findings. Hippocampus, 10, 88-93.

This research was supported by NIAAA grant 1 R03 AA018214-01A1

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Effects of Ethanol on Double Rule Switch*

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Effects of Ethanol on Single Rule Switch

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