SUBCORTICAL NETWORKS CONTROLLING HIPPOCAMPAL ACTIVITY
Laboratory of Neurophysiology, Massachusetts Mental Health Center
Bernat Kocsis, Ph.D., J. Allan Hobson, M.D., Viktor Varga, M.A.
The central focus of this project is the subcortical regulation of hippocampal function and is guided by the general hypothesis that the role of this regulation is to switch the hippocampal EEG between theta and non-theta patterns and to build dynamic associations between several limbic structures that are synchronized by the theta rhythm. The major goal of the proposed research is to replace the existing simplistic model of a unidirectional theta generating pathway with a more realistic network model which would explain different types of rhythmic coordination of cooperative brain regions depending on behavioral states in which theta is prominent; awake exploration and REM sleep. The methods we use include extracellular recording of the activity of neuronal ensembles in naturally behaving animals during the sleep-waking cycle, in vivo microdialysis, juxtacellular labeling of neurons, and microinjections of pharmacological agents in brainstem structures.
Key words: basic neuroscience, sleep, memory, hippocampus, brainstem, hypothalamus, theta rhythm
Grant support: NIMH R01 MH62525: Cooperation among subcortical networks underlying memory (BK), John W. Milton Fund: Cellular mechanisms of the brainstem serotonergic control in REM sleep (BK)
Project Site: Massachusetts Mental Health Center
Project director: Bernat Kocsis, Ph.D., Laboratory of Neurophysiology, Massachusetts Mental Health Center, 74 Fenwood Rd. Boston, MA 02115
Contact person: Dr. Bernat Kocsis; voice (617)626-9539; FAX (617) 734-7851; e-mail: bkocsis@http://hms.harvard.edu
Training opportunities: Currently there is 1 post-doctoral fellow and 2 undergraduate students. Opportunities exist for both undergraduate honors students and post-doctoral fellows.
Representative publications:
B. Kocsis, R.P. Vertes. Characterization of neurons in the supramammillary nucleus and mammillary body synchronously firing with the theta rhythm of the hippocampus. J. Neurosci., 14:7040-7052, 1994.
B. Kocsis, A. Bragin, G. Buzsaki. Interdependence of multiple theta generators in the hippocampus: a partial coherence analysis. J. Neurosci., 19:6200-6212, 1999.
B. Kocsis, G. Viana Di Prisco, R.P. Vertes. Theta Synchronization in the Limbic System: The Role of Gudden's Tegmental Nuclei, Eur. J. Neurosci., 13:381-388, 2001.
V. Varga, A. Sik, T. F. Freund, B. Kocsis. GABAB receptors in the median raphe nucleus: distribution and role in the serotonergic control of hippocampal activity. Neurosci., 109:119-132, 2002.