Identifier

62

Date

2015

Document Type

Honors Thesis

Degree Name

Bachelor of Arts

Major

Psychology

Concentration

Behavioral Neuroscience

Committee Member

Helen Sable

Abstract

The N100 component of an event-related potential (ERP) represents the initial negative peak occurring approximately 80-120 msec after stimulus onset. It is independent of task demand and the amplitude and latency are affected by certain characteristics of the stimulus such as predictability, inter-stimulus interval, loudness, etc. Likewise, characteristics of the participant like age, education level, mental health status, drug intoxication, family history of addiction, and sleep deprivation also affect the amplitude of the auditory N100. The N100 is generated during sleep, but reports indicate the latency of the N100 is delayed. Anesthesia has been reported to reduce the amplitude of the N100 as well, but research examining anesthesia effects on N100 amplitude and latency is limited. This study used subdermal needle electrodes in Wistar rats to examine isoflurane effects (1-2% in pure oxygen) on auditory N100 amplitude and latency over a 20 minute session. The stimuli were 90 dB complex tones with a 500-Hz fundamental and harmonics at 1000 and 1500 Hz (-3 dB and -6 dB, respectively, relative to the fundamental), were each 50 ms in duration (5-ms Gaussian onset/offset periods), and presented 500-ms apart. The duration between the tone pairs was randomized and was either a short inter-pair interval (IPI, 1 sec) or long IPI (5 sec). The isoflurane was then discontinued, and subjects allowed to awaken fully, at which point the recording procedure to the tone pairs was repeated. Results demonstrated a decrease in N100 response amplitude at both the short and long IPI during anesthesia. Likewise, the N100 latency was also affected by isoflurane. These results confirm that the characteristics of the N100 are substantially modified by anesthesia. Thus, measuring for abnormalities in the auditory system in anesthetized patients using the N100 is not advisable. On the other hand, recording the auditory N100 may provide useful information about optimal levels of sedation/anesthesia.

Comments

Undergraduate Honor's Thesis

Library Comment

Honors thesis originally submitted to the Local University of Memphis Honor’s Thesis Repository.

Notes

Data is provided by the student.

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