Recent research has shown that drugs that induce state-dependent memory (SDM) also produce profound alterations in mood. Notably, the manipulation of mood alone at learning and retrieval produces strong dissociations in memory. Thus, it has been proposed that drug-induced state dependent effects are due to the mood states that these drugs generate. Caffeine produces substantial mood alterations that vary predictably with dose, and is a safe and viable model for studying the mechanisms of drug abuse. Preliminary work has revealed that, in rodents, conditioned responding to caffeine-associated stimuli is dependent upon, the dose of caffeine received, and that emotion potentiates cue salience in human context-dependent memory. Synthesizing these points, if state- dependent memory is mediated by mood, and if the subjective and behavioral effects of caffeine are correlated to the dose consumed, then one can test the proposed role of mood in SDM by manipulating the dose of caffeine received during learning and retrieval.
The aims of this research proposal are to determine whether and at what doses caffeine can induce SDM (AIM 1), and whether the occurrence of such effects is conditional upon congruence in the mood states that caffeine induces (AIM 2). This will be done by varying the dose of caffeine (O, 2.14mg/kg, 5.00 mg/kg, 7.86 mg/kg) that subjects receive at the incidental learning and free recall retrieval sessions of a traditional SDM experiment (4x4 between subjects design). The to-be-remembered items will be a list of neutral nouns. Mood change will be computed several times in each session and correlated with the number of words recalled. This research has implications for determining how dose and mood are involved in the state- dependent mechanisms that underlie drug abuse, and will advance our knowledge of the cognitive and emotional consequences of caffeine ingestion. The long term objective of this research program is to determine how the emotions and memories associated to drug-induced state changes stimulate drug seeking, craving, and the initiation of withdrawal symptoms.
| Herz, R S (1999) Caffeine effects on mood and memory. Behav Res Ther 37:869-79 |
