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Première conférence internationale sur le bâillement
First International Conference on Yawning
Paris 24 - 25 juin 2010
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Learning and memory of contextual fear conditioning in High Yawning rats.
Jorge García-Torres (1)
José R. Eguibar (2)
Gina L. Quirarte (1)
Roberto A. Prado-Alcalá (1)
1) Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, UNAM Campus Juriquilla, Querétaro, México.
2) Neurofisiología de la Conducta y Control Motor, Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México.
The high frequency of yawning shown by HY sub-line of rats, derived from the Sprague-Dawley (SD) strain of rats has been related to an imbalance of the central cholinergic system. It has also been reported that this neurotransmitter system is importantly involved in learning and memory of aversively-motivated tasks. Thus, high frequency of yawning and facilitation of learning and memory are observed, within certain limits, when there is an augmented cholinergic tone.
These data led us to investigate whether the processes of learning and memory of HY rats differ from those of normal Sprague-Dawley rats. Contextual fear conditioning, an aversively-motivated task, was studied. During the training session each rat was exposed to a distinct context (CS) which was paired with a foot-shock (UCS) of either 0, 1.0, or 2.0 mA, that was presented 8 times, with an interval of 1 min between foot-shocks. Long-term memory was measured at 48 and 96 h after training; during these two test sessions the foot-shocks were omitted. The conditioned response was defined as the amount of freezing across the training and test sessions.
Even though HY rats showed learning and memory of contextual fear conditioning, their performance was poorer than that of the SD rats. These impairments seen in HY rats might be related to altered cholinergic activity in these rats.

The authors gratefully acknowledge the technical assistance of Ángel Méndez, Norma Serafín, Andrea C. Medina, Martín García and Omar González. This work was supported by PAPIIT (Project IN208110).