title: The ventral midline thalamus contributes to strategy shifting in a memory task requiring both prefrontal cortical and hippocampal functions.
abstract: Electrophysiological and neuroanatomical evidence for reciprocal connections with the medial prefrontal cortex (mPFC) and the hippocampus make the reuniens and rhomboid (ReRh) thalamic nuclei a putatively major functional link for regulations of cortico-hippocampal interactions. In a first experiment using a new water escape device for rodents, the double-H maze, we demonstrated in rats that a bilateral muscimol (MSCI) inactivation (0.70 vs 0.26 and 0 nmol) of the mPFC or dorsal hippocampus (dHip) induces major deficits in a strategy shifting/spatial memory retrieval task. By way of comparison, only dHip inactivation impaired recall in a classical spatial memory task in the Morris water maze. In the second experiment, we showed that ReRh inactivation using 0.70 nmol of MSCI, which reduced performance without obliterating memory retrieval in the water maze, produces an as large strategy shifting/memory retrieval deficit as mPFC or dHip inactivation in the double-H maze. Thus, behavioral adaptations to task contingency modifications requiring a shift toward the use of a memory for place might operate in a distributed circuit encompassing the mPFC (as the potential set-shifting structure), the hippocampus (as the spatial memory substrate), and the ventral midline thalamus, and therein the ReRh (as the coordinator of this processing). The results of the current experiments provide a significant extension of our understanding of the involvement of ventral midline thalamic nuclei in cognitive processes: they point to a role of the ReRh in strategy shifting in a memory task requiring cortical and hippocampal functions and further elucidate the functional system underlying behavioral flexibility.
authors.affiliation: Laboratory of Cognitive and Adaptive Neurosciences, UMR 7364, University of Strasbourg-National Center of Scientific Research (CNRS), Federal Research Institute 37 of Neurosciences, CNRS Research Group 2905, Faculty of Psychology, F-67000 Strasbourg, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Cholvin
authors.forename: Michaël
authors.initials: M
authors.lastname: Loureiro
authors.forename: Raphaelle
authors.initials: R
authors.lastname: Cassel
authors.forename: Brigitte
authors.initials: B
authors.lastname: Cosquer
authors.forename: Karine
authors.initials: K
authors.lastname: Geiger
authors.forename: David
authors.initials: D
authors.lastname: De Sa Nogueira
authors.forename: Hélène
authors.initials: H
authors.lastname: Raingard
authors.forename: Laura
authors.initials: L
authors.lastname: Robelin
authors.forename: Christian
authors.initials: C
authors.lastname: Kelche
authors.forename: Anne
authors.initials: A
authors.lastname: Pereira de Vasconcelos
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Cassel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D016009:Chi-Square Distribution; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D013788:Thalamus / Q000187:drug effects / Q000502:physiology*
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol