This study is to better understand the systems-level neuronal mechanisms by which general anesthetics produce loss of consciousness.The researchers believe that anesthetics suppress consciousness by disrupting the functioning of large-scale brain networks that support information integration in the brain.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
47
Propofol will be administered by intravenous infusion. All anesthesia equipment, supplies, and drugs will be provided by anesthesiologists from the University of Michigan Health System. The researchers will manually control the infusion of propofol to achieve target effect-site concentrations which will be maintained for 4 minutes each. Four types of music, including Jazz, Rock, Pop and Country, will be presented in a pseudo-randomized order. During the behavioral test period, participants will be asked to squeeze an Magnetic Resonance Imaging (MRI) compatible grip dynamometer (a rubber ball) for every 10-second periods (96 cycles in total). The beginning of each cycle will be cued with the spoken word "squeeze".
The University of Michigan
Ann Arbor, Michigan, United States
Blood Oxygen Level Dependent (BOLD) Response to Sensory Stimuli During Sedation
Music evoked activity was quantified by measurements of the fMRI BOLD signal. Neural response to a natural auditory stimulus, music, was assessed during both conscious and anesthetized states. Measurements were taken at baseline (30 minutes) and during anesthesia (60 minutes).
Time frame: 60 minutes
Average Squeeze Pressure Over 60 Minutes
Measurement of force of participants' hand squeezing on a rubber ball in response to instructions. This will be measured in millimeters of mercury (mmHg) of air pressure during squeezing the rubber ball. Measurements are provided for the 30-minute means based on measurements taken every 10 seconds for 30 minutes prior to intervention (baseline) and every 10 seconds for 30 minutes during intervention (intervention), using BIOPAC (https://www.biopac.com) MP160 system with AcqKnowledge software (V5.0).
Time frame: 60 minutes
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