Summary
The firing of lateral septal neurons was examined in relation to the hippocampal theta rhythm in urethane anesthetized rats. In general, the firing rates of these cells were low during both theta and non-theta EEG states. There was no significant change in firing rate between the two states (theta: 8.5±9.9 spks/sec; non-theta: 6.0±5.3). Sixty-four of 68 cells fired simple spikes and 4 cells were found to fire bursts of action potentials (complex-spikes). Approximately 30% (21/65) of the cells showed a significant phase relation to the hippocampal theta rhythm. The preferred phases of firing of these 21 cells were broadly distributed. The possibility that the phase-locked firing of LSN cells is due to the phase-locked firing of hippocampal projection cells is discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Amaral DG, Kurz J (1985) An analysis of the origins of the cholinergic and noncholinergic septal projections to the hippocampal formation of the rat. J Comp Neurol 240:37–59
Batschelet E (1981) Circular statistics in biology. Academic Press, London
DeFrance JF, Shimono T, Kitai ST (1971) Anatomical distribution of the hippocampal fibers afferent to the lateral septal nucleus. Brain Res 34:176–180
DeFrance JF, Kitai ST, Shimono T (1973) Electrophysiological analysis of the hippocampal-septal projections. I. Response and topographical characteristics. Exp Brain Res 17:447–462
DeFrance JF, Yoshihara H, Chronister RB (1976) Electrophysiological studies of the septal nuclei. I. The lateral septal nuclei. Exp Neurol 53:399–419
Fox SE, Wolfson S, Ranck JB Jr (1986) Hippocampal theta rhythm and the firing of neurons in walking and urethane anesthetized rats. Exp Brain Res 62:495–508
Gutnick MJ, Feldman S (1977) Effects of hippocampal and hypothalamic afferents on neuronal activities in the rat septum. Exp Neurol 57:212–230
Joëls M, Urban IJA (1985) Topographic organization of fimbria/fornix fibers projecting to the lateral septum of rats: a single and field response analysis. Exp Neurol 87:474–486
McLennan H, Miller JJ (1974) The hippocampal control of neuronal discharges in the septum of the rat. J Physiol (Lond) 237:607–624
Meibach RC, Siegel A (1977) Efferent connections of the hippocampal formation in the rat. Brain Res 124:197–224
Paxinos G, Watson C (1982) The rat brain in stereotaxic coordinates. Academic Press, Sydney
Ranck JB Jr (1973) Studies on single neurons in dorsal hippocampal formation and septum in unrestrained rats. I. Behavioral correlates and firing repertoires. Exp Neurol 41:461–531
Ranck JB Jr (1976) Behavioral correlates and firing repertoires of neurons in septal nuclei in unrestrained rats. In: DeFrance JF (ed) The septal nuclei. Plenum Press, New York, pp 423–462
Stewart M, Fox SE (1987) Phases of firing of medial and lateral septal neurons and the importance of hippocampal feedback. Soc Neurosci Abstr 13:1331
Stewart M, Fox SE (1989a) Two populations of rhythmically bursting neurons in the rat medial septum are revealed by atropine. J Neurophysiol 61:982–993
Stewart M, Fox SE (1989b) Firing relations of medial septal neurons to the hippocampal theta rhythm in urethane anesthetized rats. Exp Brain Res 77: 507–516
Swanson LW, Cowan WM (1977) An autoradiographic study of the organization of the efferent connections of the hippocampal formation in the rat. J Comp Neurol 172:49–84
Swanson LW, Cowan WM (1979) The connections of the septal region in the rat. J Comp Neurol 186:621–656
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Stewart, M., Fox, S.E. Firing relations of lateral septal neurons to the hippocampal theta rhythm in urethane anesthetized rats. Exp Brain Res 79, 92–96 (1990). https://doi.org/10.1007/BF00228876
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00228876