Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses

Abstract

Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it’s unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆L and ∆I) were extracted during anesthesia. ∆L and ∆I monitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia, and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆L and ∆I. However, ∆L was changed by the hypothermia, whereas ∆I was changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆L monitors the effect of hypothermia on nerve fibers, and ∆I monitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the anesthesia effect on synapses.

Septal and Hippocampal Neurons Contribute to Auditory Relay and Fear Conditioning

“…As in our previous experiments ( Xiong et al, 2013 ; Huang et al, 2015 ; Wang et al, 2017 ), sodium pentobarbital (60–70 mg/kg, i.p., Sigma, United States) and atropine sulfate (0.25 mg/kg, s.c., Nandao, Hainan, China) were injected into each mouse for anesthesia and inhibition of respiratory secretions, respectively. The effects of anesthesia on each mouse were examined using the pedal withdrawal reflex and were maintained by supplemental doses (13 mg/kg) of pentobarbital during the surgery.…”

“…As in our previous experiments ( Xiong et al, 2013 ; Huang et al, 2015 ; Wang et al, 2017 ), acoustic stimuli (1–50 kHz noise and 2–64 kHz tone bursts, 50 ms in duration and 5 ms rise/fall time) were generated using a Tucker-Davis Technologies System 3 (TDT 3, Tucker-Davis Technologies, Alachua, FL, United States). The intensities were controlled by a programmable attenuator (PA5).…”

The Effect of Sedation on Cortical Activation: A Randomized Study Comparing the Effects of Sedation With Midazolam, Propofol, and Dexmedetomidine on Auditory Processing

“…The concept of AEP has been used to assess anesthetic depth. 22,23 Auditory latency has been described as an effective index for the effects of general anesthetics 24–26 although these anesthetic effects are only notable at doses used to maintain full anesthesia 27 or higher sedation doses. 28 One of the key differences in AEP and auditory fMRI is that AEP monitor brain stem responses.…”

Robust and Intensity-Dependent Synaptic Inhibition Underlies the Generation of Non-monotonic Neurons in the Mouse Inferior Colliculus

“…All mice prepared for electrophysiological recording experiments were subjected to surgery following our previously reported methods (Tan et al, 2008; Huang et al, 2015; Wei et al, 2018). After atropine sulfate (0.25 mg/kg, Nandao, Hainan, China) was injected subcutaneously to reduce tracheal mucous secretion, mice were anesthetized with sodium pentobarbital (60–70 mg/kg, i.p.).…”