Physiological evidence for a possible projection from dorsal subiculum to hippocampal area CA1

The substantial forward projection from hippocampal area CA1 to the subiculum has been comprehensively described, both anatomically and neurophysiologically. There are few data, however, regarding the existence of a backward projection from the subiculum to area CA1. We present here new electrophysiological evidence for the existence of this projection. We demonstrate a positive-going deflection in the evoked synaptic response in area CA1 following stimulation in dorsal subiculum. We also found a small, but significant, paired-pulse facilitatory effect at a 100-ms interstimulus interval. We were unable to induce long-term potentiation following high-frequency stimulation, but were able to induce short-term potentiation.

[1]  Nobuaki Tamamaki,et al.  Disposition of the slab‐like modules formed by axon branches originating from single CA1 pyramidal neurons in the rat hippocampus , 1990, The Journal of comparative neurology.

[2]  H. Boddeke,et al.  Activation of 5-HTIB receptors suppresses low but not high frequency synaptic transmission in the rat subicular cortex in vitro , 1996, Brain Research.

[3]  D. Amaral,et al.  Organization of intrahippocampal projections originating from CA3 pyramidal cells in the rat , 1990, The Journal of comparative neurology.

[4]  M. Witter,et al.  Functional organization of the extrinsic and intrinsic circuitry of the parahippocampal region , 1989, Progress in Neurobiology.

[5]  M. Witter,et al.  Perirhinal cortex input to the hippocampus in the rat: evidence for parallel pathways, both direct and indirect. A combined physiological and anatomical study , 1999, The European journal of neuroscience.

[6]  O. Steward,et al.  Topographic organization of the projections from the entorhinal area to the hippocampal formation of the rat , 1976, The Journal of comparative neurology.

[7]  D. Finch,et al.  Responses of rat subicular neurons to convergent stimulation of lateral entorhinal cortex and CA1 in vivo , 2000, Brain Research.

[8]  F. H. Lopes da Silva,et al.  Anatomic organization and physiology of the limbic cortex. , 1990, Physiological reviews.

[9]  G. Paxinos,et al.  The Rat Brain in Stereotaxic Coordinates , 1983 .

[10]  D. Amaral,et al.  The three-dimensional organization of the hippocampal formation: A review of anatomical data , 1989, Neuroscience.

[11]  A. Mason,et al.  Electrophysiology and burst-firing of rat subicular pyramidal neurons in vitro: a comparison with area CA1 , 1993, Brain Research.

[12]  Mark Stewart,et al.  Propagation of synchronous epileptiform events from subiculum backward into area CA1 of rat brain slices , 2001, Brain Research.

[13]  L. Swanson,et al.  Projections of the ventral subiculum to the amygdala, septum, and hypothalamus: A PHAL anterograde tract‐tracing study in the rat , 1992, The Journal of comparative neurology.

[14]  S. O’Mara,et al.  The effects of single and multiple episodes of theta patterned or high frequency stimulation on synaptic transmission from hippocampal area CA1 to the subiculum in rats , 1999, Neuroscience Letters.

[15]  M. Witter,et al.  The Rat Nervous System , 1995 .

[16]  D. Amaral,et al.  Organization of CA1 projections to the subiculum: A PHA‐L analysis in the rat , 1991, Hippocampus.

[17]  T. Babb,et al.  Neurophysiology of the caudally directed hippocampal efferent system in the rat: Projections to the subicular complex , 1980, Brain Research.

[18]  S. O’Mara,et al.  Interaction between paired-pulse facilitation and long-term potentiation in the projection from hippocampal area CA1 to the subiculum. , 1998, Neuroreport.

[19]  Stanley J. Watson,et al.  The rat brain in stereotaxic coordinates (2nd edn) by George Paxinos and Charles Watson, Academic Press, 1986. £40.00/$80.00 (264 pages) ISBN 012 547 6213 , 1987, Trends in Neurosciences.

[20]  S. O’Mara,et al.  The subiculum: a review of form, physiology and function , 2001, Progress in Neurobiology.

[21]  F. H. Lopes da Silva,et al.  Evidence for a direct projection from the postrhinal cortex to the subiculum in the rat , 2001, Hippocampus.

[22]  J. Taube.  Electrophysiological properties of neurons in the rat subiculum in vitro , 2004, Experimental Brain Research.

[23]  P. E. Sharp,et al.  Spatial correlates of firing patterns of single cells in the subiculum of the freely moving rat , 1994, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[24]  G. M. Rose,et al.  Induction of hippocampal long-term potentiation using physiologically patterned stimulation , 1986, Neuroscience Letters.

[25]  M. Witter,et al.  Heterogeneity in the Dorsal Subiculum of the Rat. Distinct Neuronal Zones Project to Different Cortical and Subcortical Targets , 1990, The European journal of neuroscience.

[26]  S M O'Mara,et al.  The projection from hippocampal area CA1 to the subiculum sustains long‐term potentiation , 1998, Neuroreport.

[27]  S M O'Mara,et al.  Synaptic plasticity in the hippocampal area CA1‐subiculum projection: Implications for theories of memory , 2000, Hippocampus.