Carbachol-induced EEG ‘theta’ activity in hippocampal brain slices

Endogenous Waves in Hippocampal Slices

“…First, theta rhythms are generated in vivo by ascending cholinergic inputs from the medial septum/ diagonal band (Vertes and Kocsis 1997 for a review) and under some in vitro conditions by application of carbachol (Huerta and Lisman 1993;Konopacki et al 1987), while the activity recorded in the present study occurred spontaneously in isolated hippocampus and was suppressed by cholinergic stimulation. Also, the in vitro waves had an irregular pattern, their frequency and amplitude varying widely from cycle to cycle within a slice, whereas theta rhythms exhibit a relatively uniform pattern.…”

“…Rhythms (theta, beta, gamma) similar to those found in vivo appear in brain slices following infusion of cholinergic agonists (Fellous et al 2000;Fisahn et al 1998;Huerta and Lisman 1993;Konopacki et al 1987;Shimono et al 2000;Williams and Kauer 1997). Analyses of these in vitro oscillations have contributed significantly to the elucidation of how cholinergically dependent rhythms are generated within hippocampus.…”

“…6B). At higher concentrations, carbachol induces rhythmic activity in slices (Fellous et al 2000;Fisahn et al 1998;Huerta and Lisman 1993;Konopacki et al 1987;Shimono et al 2000;Williams and Kauer 1997), which could have precluded expression of the spontaneous slow activity. However, examination of power spectra over time for slices in which carbachol was infused at a concentration of 20 M (n ϭ 4, data not shown) showed that the disappearance of the slow activity preceded the development of the cholinergically driven rhythms, suggesting that cholinergic activation in itself suppressed the former waves at concentrations lower than those required to generate cholinergic rhythms.…”

Computational model of carbachol‐induced delta, theta, and gamma oscillations in the hippocampus

“…Furthermore, recent experiments indicate that the intrinsic properties of the isolated CA3 region in the hippocampus contribute to theta rhythms observed in vivo (Kocsis et al, 1999). Muscarinic activation of the CA3 region, using the agonist carbachol, results in synchronous population activity in the delta (Boguszewicz et al, 1996;Fellous and Sejnowski, 2000), theta (Bland et al, 1988;Fellous and Sejnowski, 2000;Konopacki et al, 1987;MacVicar and Tse, 1989;Williams and Kauer, 1997), and gamma (Fellous and Sejnowski, 2000;Fisahn et al, 1998) bands. These intracellular studies have shown that cholinergically induced delta and theta (CCH-␦ and CCH-) oscillations depended on the pyramidal cell network of the CA3 region, but gamma (CCH-␥) also required an intact network of GABAergic interneurons.…”

Cholinergic plasticity in the hippocampus

“…These pathways generate rhythmic activity of various frequencies (14)(15)(16)(17)(18), some aspects of which can be reproduced in hippocampal slices by infusing cholinergic agonists (19)(20)(21)(22)(23). The in vitro rhythms are mediated by mAChRs (19,20,22,23) and originate in the CA3 region from whence they move along intrahippocampal pathways to other subfields (22,23).…”