title: A time-dependent role of midline thalamic nuclei in the retrieval of fear memory.
abstract: Increasing evidence indicates that the medial prefrontal cortex (mPFC) and the amygdala mediate expression and extinction of conditioned fear, but few studies have examined the inputs to these structures. The dorsal part of the midline thalamus (dMT) contains structures such as the mediodorsal nucleus, paraventricular nucleus, and paratenial nucleus that project prominently to mPFC, as well as to basal (BA) and central (Ce) nuclei of the amygdala. Using temporary inactivation with GABA agonist muscimol, we found that dMT was necessary for retrieving auditory fear memory that was 24 h old, but not 2-8 h old. However, pre-training infusions did not impair fear acquisition or extinction. To determine the possible targets of dMT that might modulate fear retrieval, we combined dMT inactivation with Fos immunohistochemistry. Rats with inactivation-induced impairment in fear retrieval showed increased Fos in the lateral division of Ce (CeL), and decreased Fos in the medial division of Ce. No differences in Fos expression were observed in the mPFC or BA. We suggest that the projections from the paraventricular nucleus to CeL are involved in retrieval of well consolidated fear memories. This article is part of a Special Issue entitled 'Anxiety and Depression'.
authors: Department of Psychiatry, University of Puerto Rico School of Medicine, P.O. Box 365067, San Juan 00936, Puerto Rico.
authors: Nancy
authors: N
authors: Padilla-Coreano
authors: Fabricio H
authors: FH
authors: Do-Monte
authors: Gregory J
authors: GJ
authors: Quirk
mesh_terms: D000161:Acoustic Stimulation / Q000009:adverse effects; D000704:Analysis of Variance; D000818:Animals; D003214:Conditioning, Classical / Q000187:drug effects*; D005108:Extinction, Psychological / Q000187:drug effects; D005239:Fear / Q000187:drug effects / Q000523:psychology*; D018755:GABA Agonists / Q000494:pharmacology; D008124:Locomotion / Q000187:drug effects; D008297:Male; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology*; D020644:Midline Thalamic Nuclei / Q000502:physiology*; D009118:Muscimol / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology; D016761:Oncogene Proteins v-fos / Q000097:blood / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D018755:GABA Agonists; D016761:Oncogene Proteins v-fos; D009118:Muscimol