Experimental design for the exposure groups of the proton magnetic resonance spectroscopy (1HMRS) portion of testing. (A) Animals were divided into two anesthesia exposure groups, single exposure and multiple exposure, with the total duration of anesthesia being 6 h for both. (B) Each animal underwent repeated testing using 1HMRS at 1, 2, 3, and 4 weeks of age. (C) The thalamus was identified using three orthogonal planes, and a voxel was placed over the thalamus of both hemispheres. (D) Spectrum were then acquired and processed to provide the concentration of NAA in the live animal brain. Cb = cerebellum; GABA = gamma amino butyric acid; Glu = glutamate; Glx = glutamate and glutamine; Lac = lactate; mI = myoinositol; MM = macromolecules; NAA = N-acetyl-aspartate; Olfac = olfactory bulb; PND = postnatal day; Tau = taurine; tCho = total choline; tCr = total creatinine.