NMDA receptor-dependent oscillatory signal outputs from the retrosplenial cortex triggered by a non-NMDA receptor-dependent signal input from the visual cortex

• Published in: Brain research 2005-05, Vol.1045 (1), p.12-21
• Main Authors: Yoshimura, Hiroshi, Sugai, Tokio, Honjo, Makoto, Segami, Natsuki, Onoda, Norihiko
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological Clocks - drug effects; Biological Clocks - physiology; Caffeine; Caffeine - pharmacology; Excitatory Amino Acid Antagonists - pharmacology; Eye and associated structures. Visual pathways and centers. Vision; Fluorescent Dyes; Fundamental and applied biological sciences. Psychology; Glutamic Acid - metabolism; Gyrus Cinguli - anatomy & histology; Gyrus Cinguli - drug effects; Gyrus Cinguli - physiology; Hippocampus - anatomy & histology; Hippocampus - physiology; Horizontal propagation; Medical sciences; Neuropharmacology; Optical recording; Optics and Photonics; Organ Culture Techniques; Oscillation; Pharmacology. Drug treatments; Psychoanaleptics: cns stimulant, antidepressant agent, nootropic agent, mood stabilizer..., (alzheimer disease); Psychology. Psychoanalysis. Psychiatry; Psychopharmacology; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate - drug effects; Receptors, N-Methyl-D-Aspartate - metabolism; Retrosplenial cortex; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Vertebrates: nervous system and sense organs; Visual cortex; Visual Cortex - anatomy & histology; Visual Cortex - drug effects; Visual Cortex - physiology; Visual Pathways - anatomy & histology; Visual Pathways - drug effects; Visual Pathways - physiology
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.02.084

The retrosplenial cortex is located at a critical juncture between the visual cortex and hippocampal formation. Functions of the retrosplenial cortex at the local circuit level, however, remain unclear. Herein, we show how signals traveling from the visual cortex behave in local circuits of the retrosplenial cortex, using optical recording methods and application of caffeine to rat brain slices. Electrical signals evoked in the primary visual cortex penetrated into the deep layer of the retrosplenial granular a cortex (RSGa) and propagated further toward postsubiculum and upper layer. Non- N-methyl- d-aspartate (NMDA) receptor-dependent initial traveling signal from the visual cortex triggered NMDA receptor-dependent neural oscillation in the RSGa. Oscillatory signals originated from the local area in the deep layer of the RSGa, and the signal spread back and forth toward the visual cortex and postsubiculum, in addition to spreading toward the upper layer. From the perspective of the RSGa, extrinsic signal inputs from the visual cortex switched on neural oscillators in the RSGa that deliver NMDA receptor-dependent intrinsic signal outputs. Opening and strengthening of non-NMDA receptor-dependent input pathways from the visual cortex required NMDA receptor-dependent oscillatory neural activities. These input and output relationships indicate that the retrosplenial cortex may represent an important relay station between the visual cortex and hippocampal formation.