English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/32475
Title: Characteristics of CA1 activation through the hippocampal trisynaptic pathway in the unanaesthetized rat
Authors: Herreras, Óscar; Solís, José M.; Martín del Río, Rafael; Lerma Gómez, Juan
Keywords: Neuronal transmission
Trisynaptic circuit
θ Rhythm
Evoked potential
Issue Date: 9-Jun-1987
Publisher: Elsevier
Citation: Brain Research 413(1): 75-86 (1987)
Abstract: The hippocampal CA1 field is activated by the entorhinal cortex mainly through the hippocampal excitatory trisynaptic circuit. Field responses of the CA1 region were evoked by ipsilateral CA3 or perforant path volleys (mono- or trisynaptic activation, respectively) in paralyzed, locally anaesthetized rats and studied as a function of the stimulus patterns presented. The relationship of these responses with the concomitant EEG was also explored. Results showed that mono- and especially trisynaptically evoked responses were progressively enhanced by increasing the stimulus frequency from 0.1 to 1.0 Hz. At specific intensities the trisynaptically evoked population spike (PS) was present only with a rather fixed frequency of stimulation (0.5 Hz). PS was produced in 100% of the responses using 0.7 Hz, indicating the existence of a threshold-like level for this stimulus parameter. The frequency of presented paired pulses differentially affected pair-pulse facilitation of mono- and trisynaptically evoked excitatory postsynaptic potentials (EPSP): higher frequency decreased the former and increased the latter. All evoked responses studied (i.e. EPSP and PS) showed steep increments and decrements in amplitude, clearly developing several clusters. Moreover, the amplitude distribution of trisynaptic PS often varied spontaneously from maximal to negligible values, showing an all-or-none distribution. Clustering was interpreted as evidence of the existence in the hippocampus of functional neuronal aggregates. All-or-none distribution of trisynaptic PS was found to be associated with the EEG pattern, PS amplitude being maximal during irregular EEG activity and minimal during θ rhythm. Present results suggest that (1) the entorhinal cortex may exert modulatory actions on CA1 by a mechanism widely based on the frequency of the input; (2) information transfer from the entorhinal cortex to other brain areas throughout the hippocampus is biased by hippocampal EEG; and (3) electronic coupling may be functionally predominant in the hippocampus.
Description: 12 páginas, 8 figuras.
Publisher version (URL): http://dx.doi.org/10.1016/0006-8993(87)90155-7
URI: http://hdl.handle.net/10261/32475
DOI: 10.1016/0006-8993(87)90155-7
ISSN: 0006-8993
Appears in Collections:(IC) Artículos
Files in This Item:
There are no files associated with this item.
Show full item record

WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.