title: Inactivation of the nucleus reuniens/rhomboid causes a delay-dependent impairment of spatial working memory.
abstract: Inactivation of the rodent medial prefrontal cortex (mPFC) and hippocampus or disconnection of the hippocampus from the mPFC produces deficits in spatial working memory tasks. Previous studies have shown that delay length determines the extent to which mPFC and hippocampus functionally interact, with both structures being necessary for tasks with longer delays and either structure being sufficient for tasks with shorter delays. In addition, inactivation of the nucleus reuniens (Re)/rhomboid nucleus (Rh) of the thalamus, which has bidirectional connections with the mPFC and hippocampus, also produces deficits in these tasks. However, it is unknown how delay duration relates to the function of Re/Rh. If Re/Rh are critical in modulating mPFC-hippocampus interactions, inactivation of the RE/Rh should produce a delay-dependent impairment in spatial working memory performance. To investigate this question, groups of rats were trained on one of three different spatial working memory tasks: continuous alternation (CA), delayed alternation with a five-second delay (DA5), or with a thirty-second delay (DA30). The Re/Rh were inactivated with muscimol infusions prior to testing. The results demonstrate that inactivation of RE/Rh produces a deficit only on the two DA tasks, supporting the notion that the Re/Rh is a critical orchestrator of mPFC-HC interactions.
authors.affiliation: Department of Psychological and Brain Sciences, University of Delaware, United States.
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Layfield
authors.affiliation: Department of Psychological and Brain Sciences, University of Delaware, United States.
authors.forename: Monica
authors.initials: M
authors.lastname: Patel
authors.affiliation: Department of Psychological and Brain Sciences, University of Delaware, United States.
authors.forename: Henry
authors.initials: H
authors.lastname: Hallock
authors.affiliation: Department of Psychological and Brain Sciences, University of Delaware, United States. Electronic address: amygriff@psych.udel.edu.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Griffin
mesh_terms: D000818:Animals; D058785:GABA-A Receptor Agonists / Q000494:pharmacology; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects*; D020644:Midline Thalamic Nuclei / Q000187:drug effects*; D009118:Muscimol / Q000494:pharmacology; D051381:Rats; D065852:Spatial Memory / Q000187:drug effects*
chemical_list: D058785:GABA-A Receptor Agonists; D009118:Muscimol
keywords: Hippocampus; Prefrontal; Reuniens; Rhomboid; Ventral midline thalamus; Working memory