| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 6262161 | Brain Research Bulletin | 2012 | 13 Pages |
Slow cortical rhythm (SCR) is characterized by rhythmic cycling of active (UP) and silent (DOWN) states in cortical cells. In urethane anesthesia, SCR appears as alternation of almost isoelectrical EEG periods and low-frequency, high-amplitude large shifts with superimposed high-frequency activity in the local field potentials (LFPs). Dense cholinergic projection reaches the cortex from the basal forebrain (BF), and acetylcholine (ACh) has been demonstrated to play a crucial role in the regulation of cortical activity. In the present experiments, cholinergic drugs were administered topically to the cortical surface of urethane-anesthetized rats to examine the direct involvement of ACh and the BF cholinergic system in the SCR.SCR was recorded by a 16-pole vertical electrode array from the hindlimb area of the somatosensory cortex. Multiple unit activity (MUA) was recorded from layer V to VI in close proximity of the recording array. Neither a low dose (10Â mM solution) of the muscarinic antagonist atropine or the nicotinic agonist nicotine (1Â mM solution) had any effect on SCR. In contrast, the higher dose (100Â mM solution) of atropine, the cholinergic agonist carbachol (32Â mM solution), and the cholinesterase inhibitor physostigmine (13Â mM solution) all decreased the number of UP states, delta power (0-3Â Hz) and MUA.These results suggest that cholinergic system may influence SCR through muscarinic mechanisms during urethane anesthesia. Cholinergic activation obstructs the mechanisms responsible for local or global synchronization seen during SCR as this rhythm was disrupted or aborted. Muscarinic antagonism can evoke similar changes when high dose of atropine is applied.
⺠Interaction of slow cortical rhythm and basal forebrain was examined in rats. ⺠Topical drug application on the cortical surface. ⺠Low atropine dose and nicotine had no effect on the slow cortical rhythm. ⺠High atropine dose, carbachol and physostigmine disrupted or aborted the rhythm.
