Turn it off, turn me on: decreased motivation and interval timing under constant light

BUSSI I.L.; GOLOMBEK, D.A.; AGOSTINO P.V.

Huerta Grande, Córdoba

Congreso; XXVIII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2013

Time perception in the second-to-minutes range, called interval timing, is crucial for multiple cognition processes such as learning, memory and decision making [1]. We have previously reported that learning to time is influenced by the circadian system [2]. In this sense, our previous results indicate that mice with circadian arrhythmicity -caused by constant light- were unable to perform interval timing. To investigate if this deficit could be related to abnormal locomotor activity or anxiety levels, we used both the open-field and elevated plus maze tests. Mice under constant light showed no significant differences in locomotion or anxiety levels. Additionally, we found normal long-term recognition memory in the novel object recognition (NOR) task, indicating that cognitive functions are not affected by constant light. On the other hand, impaired interval timing may be related to motivational deficits [3]. We performed a progressive ratio (PR) task to assay motivational effects. Our results reveal that mice with circadian arrhythmicity displayed lower motivation compared to controls. This result correlates with a loss of striatal dopamine rhythmicity under constant light conditions, suggesting that dopamine might be a connection between the circadian system and interval timing, trough motivational effects. [1] Lustig et al., 2005, Memory, 13:441. [2] Agostino et al.,2011, Brain Res, 1370:154. [3] Galtress et al., 2012, Behav Processes, 90:142.