title: Brief anesthesia, but not voluntary locomotion, significantly alters cortical temperature.
abstract: Changes in brain temperature can alter electrical properties of neurons and cause changes in behavior. However, it is not well understood how behaviors, like locomotion, or experimental manipulations, like anesthesia, alter brain temperature. We implanted thermocouples in sensorimotor cortex of mice to understand how cortical temperature was affected by locomotion, as well as by brief and prolonged anesthesia. Voluntary locomotion induced small (∼ 0.1 °C) but reliable increases in cortical temperature that could be described using a linear convolution model. In contrast, brief (90-s) exposure to isoflurane anesthesia depressed cortical temperature by ∼ 2 °C, which lasted for up to 30 min after the cessation of anesthesia. Cortical temperature decreases were not accompanied by a concomitant decrease in the γ-band local field potential power, multiunit firing rate, or locomotion behavior, which all returned to baseline within a few minutes after the cessation of anesthesia. In anesthetized animals where core body temperature was kept constant, cortical temperature was still > 1 °C lower than in the awake animal. Thermocouples implanted in the subcortex showed similar temperature changes under anesthesia, suggesting these responses occur throughout the brain. Two-photon microscopy of individual blood vessel dynamics following brief isoflurane exposure revealed a large increase in vessel diameter that ceased before the brain temperature significantly decreased, indicating cerebral heat loss was not due to increased cerebral blood vessel dilation. These data should be considered in experimental designs recording in anesthetized preparations, computational models relating temperature and neural activity, and awake-behaving methods that require brief anesthesia before experimental procedures.
authors.affiliation: Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania;
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Shirey
authors.affiliation: Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania; jbs21@psu.edu.
authors.forename: Jared B
authors.initials: JB
authors.lastname: Smith
authors.affiliation: Center for Neural Engineering, Bioengineering Graduate Program, Pennsylvania State University, University Park, Pennsylvania; and.
authors.forename: D'Anne E
authors.initials: DE
authors.lastname: Kudlik
authors.affiliation: Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania;
authors.forename: Bing-Xing
authors.initials: BX
authors.lastname: Huo
authors.affiliation: Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania;
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Greene
authors.affiliation: Center for Neural Engineering, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania; Department of Neurosurgery, Pennsylvania State University, University Park, Pennsylvania.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Drew
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects* / Q000502:physiology*; D002536:Cerebral Arteries / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D000069280:Electrocorticography; D005260:Female; D065818:Gamma Rhythm / Q000187:drug effects / Q000502:physiology; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009929:Organ Size; D066191:Sensorimotor Cortex / Q000098:blood supply / Q000187:drug effects* / Q000502:physiology*; D013997:Time Factors; D014836:Volition / Q000502:physiology; D014851:Wakefulness / Q000187:drug effects / Q000502:physiology
chemical_list: D000777:Anesthetics; D007530:Isoflurane
keywords: isoflurane; neocortex; temperature