Memory for time of training modulates performance on a place conditioning task in marmosets

In rodents, the expression of a reward-conditioned place preference (CPP) is regulated in a circadian pattern such that the preference is exhibited strongly at the circadian time of prior training but not at other circadian times. Because each animal is trained only at a single circadian phase, the concept of time as a context cue is derived from a rhythmic internal state rather than learned explicitly from the external cues. We now report that the same "time memory" is expressed following context conditioning in the common marmoset (Callithrix jacchus). Animals were trained at a specific time to discriminate between an unpaired context and a context paired with food reward. Marmosets were then tested for preference at circadian times that were either the same or different from the training time. Preference was expressed only when training and testing times matched. The results show that time of day learning can be generalized to this new world primate implying that a similar circadian mechanism might regulate craving for reward in diverse mammals including human beings.Fil: Valentinuzzi, Verónica Sandra. Universidade Federal do Rio Grande do Norte; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Neto, S. P. D.. Universidade Federal do Rio Grande do Norte; BrasilFil: Carneiro, B. T. S.. Universidade Federal do Rio Grande do Norte; BrasilFil: Santana, K. S.. Universidade Federal do Rio Grande do Norte; BrasilFil: Araujo, Juan Fernando. Universidade Federal do Rio Grande do Norte; BrasilFil: Ralph, Martin Roland. University of Toronto; Canad

Automated Measurement of Mouse Freezing Behavior and its Use for Quantitative Trait Locus Analysis of Contextual Fear Conditioning in (BALB/cJ × C57BL/6J)F(2) Mice

The most commonly measured mouse behavior in fear conditioning tests is freezing. A technical limitation, particularly for genetic studies, is the method of direct observation used for quantifying this response, with the potential for bias or inconsistencies. We report the use of a computerized method based on latency between photobeam interruption measures as a reliable scoring criterion in mice. The different computer measures obtained during contextual fear conditioning tests showed high correlations with hand-scored freezing; r values ranged from 0.87 to 0.94. Previously reported strain differences between C57BL/6J and DBA/2J in context-dependent fear conditioning were also detected by the computer-based system. In addition, the use of computer-scored freezing of 199 (BALB/cJ × C57BL/6J)F(2) mice enabled us to detect a suggestive gender-dependent chromosomal locus for contextual fear conditioning on distal chromosome 8 by QTL analysis. Automation of freeze scoring would significantly increase efficiency and reliability of this learning and memory test