The parafascicular nucleus and two-way active avoidance: effects of electrical stimulation and electrode implantation.
To evaluate whether electrical stimulation of the parafascicular nucleus (PF) can improve short-term (24 h) and/or long-term (21 days) retention of two-way active avoidance, rats were implanted with an electrode at this nucleus (experimental groups) or above it (control groups). After a single 30-trial acquisition session, experimental groups were submitted to a 10-min session of electrical stimulation. Results showed that the simple implantation of an electrode at the posterior PF enhanced by itself the acquisition of two-way active avoidance, in such a way that the subsequent stimulation of this region may have been unable to further improve the performance of the rats. On the other hand, parafascicular stimulation improved the 24-h retention of the task in a site-specific way, since this effect was mainly seen after stimulation of the central PF region. The facilitative effect on 24-h retention could also depend on the level of performance achieved during the acquisition session, because this improvement was only evidenced in poorly learning animals. No effects were found on 21-day retention. The present results confirm the involvement of the PF in learning and memory and the functional heterogeneity of this nucleus.
Guillazo-Blanch
G
G
Departament de Psicobiologia i de Metodologia de les Ciències de la Salut, Universitat Autònoma de Barcelona, Spain. gguillazo@seneca.uab.es
Vale-Martínez
A M
AM
Martí-Nicolovius
M
M
Coll-Andreu
M
M
Morgado-Bernal
I
I
D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D020646:Intralaminar Thalamic Nuclei / Q000502:physiology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012153:Retention, Psychology / Q000502:physiology