Association Learning and Recognition Memory in Alcoholic Korsakoff Patients Marlene Oscar-Berman and Joan L. Pulaski Neuropsychology, Volume 11, Issue 2, April 1997, Pages

Korsakoff’s Disease brain disorder which is named after Sergei Korsakoff ( ) arises from a dietary deficiency of thiamin thiamin deficiency can cause damage to several brain areas critical for memory: including the thalamus, mammillary bodies and basal forebrain common cause of Korsakoff's disease is alcoholism. Alcohol interferes with the body's ability to metabolize thiamin; additionally, alcoholic individuals tend to have poor diets, further reducing intake of thiamin tend to show general intelligence which is just as good as chronic alcoholics without the disease can include both anterograde amnesia (loss of ability to form new memories) and retrograde amnesia disruption of pre- existing memories ) they tend also to show other impairments associated with chronic alcoholism, including disorientation for time and place, apathy, and emotional blandness broken by sudden, momentary irritability, anger or pleasure

Goal of the Study To evaluate the relative contributions of association-learning and recognition-memory deficits to amnesia of alcoholic etiology Also, to consider possible changes in association learning and in recognition memory in abstinent long-term alcoholics without the amnesia of Korsakoff's syndrome Possible link between alcohol and premature aging of the brain

Background Association learning is defined as the ability to distinguish rewarded from equally familiar non-rewarded visual stimuli Recognition memory is the ability to discriminate familiar from novel items

Participants 48 right handed men forming 5 groups 8 detoxified abstinent alcoholic Korsakoff patients Ages young detoxified abstinent alcoholics Ages older detoxified abstinent alcoholic Ages young healthy non-alcoholic controls Ages older healthy non-alcoholic controls Ages 59-68

Method Participants were seated in ront of a metal panel containing 3 Plexiglas response keys, a speaker and a coin dispenser. Stimuli consisted of colored images of single “junk” objects ( slides of small toys, kitchen items, tools etc) Images were back projected for 1 s onto one of the Plexiglas keys Reinforcement consisted of a penny for every correct response or a brief tone for incorrect responses

Procedure : Experiment 1 – Association Learning Each participant was given 5 pre-training acquisition and retention trials for practice, along with instructions on what to do Each set of problems contained 10 acquisition trials followed by 10 retention trials All stimuli were displayed for 1 s, with an intertrial interval of 5 s. The acquisition trials consisted of the successive presentations, on the central key, of 10 different stimuli, half of which were rewarded and half of which were not. For the remaining 5 trials, that is, the 5 nonrewarded stimuli, a brief tone followed responses to each. In the retention phase, the participants were required to discriminate those stimuli that had been associated in memory with reward from those that had not The same 10 stimuli were presented again, but on the right key only. The left key contained a dark circle on a white background for all retention trials (to provide a constant alternative response). The positive stimuli (rewarded in the acquisition phase) were rewarded again in the retention phase, and incorrect presses to the left key (circle) merely started the intertrial interval.

Procedure : Experiment 1 – Association Learning Responses to the stimuli that had not been rewarded in the acquisition phase were not rewarded in the retention phase, but when a nonrewarded stimulus was presented, a press to the left key (circle) delivered a penny to the participant; To maximize reward in the retention phase, the participants had to respond directly to those stimuli that were rewarded in the acquisition phase and to press the dark circle (on the left key) when they saw stimuli that had not been rewarded A third presentation of the association-learning task was given after completion of the recognition-memory phase to evaluate the effect of task order. Performance by the groups was later compared with their performance on the previous administration of the association-learning problems.

Procedure: Experiment 2 – Recognition Memory The recognition task required performance on 12 unique sets of problems, with acquisition and retention phases, and each set of problems was presented twice, with different novel stimuli for each set, for a total of 240 trials. The participants' instructions and practice experiences were similar to those for Experiment 1 except that a press to the center key (during the acquisition phase) always delivered a penny. This allowed the rewarded stimuli to be discriminable at the retention test by familiarity alone. Only 5 stimuli were presented in the acquisition phase. The retention phase consisted of presentations of 10 stimuli, 5 of which were the same as those in the acquisition phase and the other 5 of which were novel stimuli. The participants were required to press the right key each time they recognized a familiar stimulus; they were to choose the constant alternative stimulus (the dark circle on the left key) if the stimulus on the right key was not one that had been seen previously. Thus, retention was measured by familiarity alone, with reward constant. All stimuli were displayed for 1 s, and the intertrial interval was doubled (to 10 s) to make the amount of time from acquisition to retention testing the same in Experiment 1 and Experiment 2. The order of presentation was the same during the acquisition and retention phases, but the order of familiar and unfamiliar stimuli followed a different random sequence for each set of problems and during each of the two repetitions of problem sets.

Results Experiment 1: Association Learning The Korsakoff participants were significantly impared compared to all 4 other groups No significant differences between the older alcoholics and the old non-alcoholics, nor between the young alcoholics and young non alcoholics There was an effect of aging The older non-alcoholics showed lower levels of association learning than both the younger groups The older alcoholics were significantly worse than the young non alcoholics, even though the older alcoholics and young alcoholics were not significantly different

Results Experiment 2: Recognition Memory In general the recognition task was easier than the association-learning task The Korsakoff participants were significantly impaired compared to all 4 other groups Like experiment 1 there was no significant difference between the old alcoholics and old non-alcoholics nor the young alcoholics and young non-alcoholics There were significant age-related differences in recognition memory for non-alcoholics controls Performance by the older non-alcoholics was poorer than that of the young non-alcoholics

Results

Discussion The results of the two experiements indicated that the memory impairments of the Korsakoff patients extended beyond recognition memory and included association learning as well Chronologically aging individuals also showed evidence of a decline in association-learning and recognition memory skills, but the decline was mild in comparison to the Korsakoff patients This results of these experiments showed clear age related effects but the findings did not support the premature aging hypothesis (chronic alcoholism may produce premature aging of the brain)