Roles of learning and motivation in preference behavior: mediation by entorhinal cortex, dorsal and ventral hippocampus.
In the latent cue preference (LCP) task, water-deprived rats alternately drink a salt solution in one distinctive compartment of a conditioned cue preference (CCP) apparatus and water in the other compartment over 8 days (training trials). They are then given a choice between the two compartments with no solutions present (preference test). Previous findings showed that this training procedure results in two parallel forms of learning: conditioning to water-paired cues (a water-CCP) and latent learning of an association between salt and salt-paired compartment cues (a salt-LCP). Experiment 1 examined these two types of learning in isolation. Results showed that expression of the salt-LCP required salt deprivation during testing, but expression of the water-CCP did not require a deprivation state during testing. Other results showed that salt-LCP learning itself involves two distinct components: (1) the latent association among neutral cues in the salt-paired compartment, and (2) motivational information about salt deprivation during testing. Previous findings also demonstrated roles for the dorsal hippocampus (DH), ventral hippocampus (VH), and entorhinal cortex (EC) in salt-LCP learning. Experiment 2 examined the involvement of these structures during acquisition or expression of salt-LCP learning. Rats with cannulas aimed at DH, VH, or EC were given infusions of muscimol, either before exposure to the salt-paired, but not the water-paired, compartment during training or before the preference test. Inactivation of the DH or EC impaired both acquisition and expression of the association between salt and salt-paired compartment cues, while inactivation of the VH disrupted the influence of motivational information about salt deprivation required to express the salt-LCP. These results suggest unique roles for the EC-DH circuit and VH in salt-LCP learning, as well as a functional dissociation between the DH and VH.
Stouffer
Eric M
EM
Department of Psychology, McGill University, Montreal, Canada. stouffere@cofc.edu
White
Norman M
NM
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003216:Conditioning, Operant / Q000187:drug effects; D003463:Cues; D018728:Entorhinal Cortex / Q000033:anatomy & histology / Q000502:physiology*; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology; D006624:Hippocampus / Q000033:anatomy & histology / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D009042:Motivation; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D012964:Sodium / Q000172:deficiency; D013649:Taste / Q000187:drug effects; D014868:Water Deprivation / Q000502:physiology
D018755:GABA Agonists; D009118:Muscimol; D012964:Sodium