The dependence of acetylcholine on dynamic changes in the membrane potential and an action potential during spike timing‐dependent plasticity induction in the hippocampus. (5th October 2022)

• Record Type: Journal Article
• Authors: Sugisaki, Eriko; Fukushima, Yasuhiro; Nakajima, Naoki; Aihara, Takeshi
• Is Part Of: European journal of neuroscience. Volume 56:Number 11(2022)
• Page Start: 5972
• Page End: 5986
• Publication Date: 2022-10-05
• Subjects: acetylcholine -- CA1 -- hippocampus -- spike timing‐dependent plasticity; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.15832
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: The hippocampus is an important area for memory encoding and retrieval and is the location of spike timing‐dependent plasticity (STDP), a basic phenomenon of learning and memory. STDP is facilitated if acetylcholine (ACh) is released from cholinergic neurons during attentional processes. However, it is unclear how ACh influences postsynaptic changes during STDP induction and determines the STDP magnitude. To address these issues, we obtained patch clamp recordings from CA1 pyramidal neurons to evaluate the postsynaptic changes during stimuli injection in Schaffer collaterals by quantifying baseline amplitudes (i.e., the lowest values elicited by paired pulses comprising STDP stimuli) and action potentials. The results showed that baseline amplitudes were elevated if eserine was applied in the presence of picrotoxin. In addition, muscarinic ACh receptors (mAChRs) contributed more to the baseline amplitude elevation than nicotinic AChRs (nAChRs). Moreover, the magnitude of the STDP depended on the magnitude of the baseline amplitude. However, in the absence of picrotoxin, baseline amplitudes were balanced, regardless of the ACh concentration, resulting in a similar magnitude of the STDP, except under the nAChR alone‐activated condition, which showed a larger STDP and lower baseline amplitude induction. This was due to broadened widths of action potentials. These results suggest that activation of mAChRs and nAChRs, which are effective for baseline amplitudes and action potentials, respectively, plays an important role in postsynaptic changes during memory consolidation. Abstract : The magnitude of the baseline amplitude contributing to STDP was determined by the balance of upregulation and downregulation abilities with AChR activation. In particular, mAChRs contributed more to an elevation of the baseline amplitude compared with nAChRs in the presence of picrotoxin. The broadened widths of the action potential influenced by nAChR activation also helped to determine the STDP magnitude when picrotoxin was untreated.