Acetylcholine modulates averaged sensory evoked responses and perforant path evoked field potentials in the rat dentate gyrus

The effect of localized application of acetylcholine (ACh) on well chacracterized components of sensory evoked and electrically induced potentials in the dentate gyrus was investigated in rats while performing a tone discrimination task. Local pressure application of ACh to the granule cell layer of...

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Bibliographic Details
Published in:	Brain research 1992-07, Vol.587 (1), p.95-101
Main Authors:	Foster, Tom C., Deadwyler, Sam A.
Format:	Article
Language:	eng
Subjects:	Acetylcholine Acetylcholine - pharmacology Animals Averaged evoked potential Dentate gyrus Discrimination Learning - drug effects Evoked Potentials, Auditory - drug effects Evoked Potentials, Auditory - physiology Evoked Potentials, Somatosensory - drug effects Field potential Hippocampus - cytology Hippocampus - drug effects Hippocampus - physiology Life Sciences & Biomedicine Male Neural Pathways - drug effects Neural Pathways - physiology Neurons, Afferent - drug effects Neurosciences Neurosciences & Neurology Parasympathetic Nervous System - drug effects Parasympathetic Nervous System - physiology Rats Rats, Inbred Strains Science & Technology Synapses - drug effects Synapses - physiology
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Summary:	The effect of localized application of acetylcholine (ACh) on well chacracterized components of sensory evoked and electrically induced potentials in the dentate gyrus was investigated in rats while performing a tone discrimination task. Local pressure application of ACh to the granule cell layer of the dentate gyrus through the recording pipette increased the amoplitude of perforant path evoked population spikes without changing the amplitude of the field EPSP. When the pipette was relocated to the outer molecular layer of the dentate (OM), ACh application decreased the amplitude of the perforant path field EPSP. Two major components of the averaged auditory evoked potential (AEP) recorded during criterion performance of the discrimination task were significantly changed by dendritic application of ACh. The N 1 component of the OM AEP which has been shown to reflect perforant path synaptic activity decreased in amplitude while the N 2 component wich represent activity from septal connections, was significantly increased. These effects were not due to pressure ejection nor drug related changes in behavioral performance of the task. The results suggest that ACh may act to differentially modulate the synaptic excitability of dentate granule cells, allowing them to acquire responses to sensory stimulation during establishment and maintenance of discrimination learning.
ISSN:	0006-8993 1872-6240