title: Cooling of the auditory cortex modifies neuronal activity in the inferior colliculus in rats.
abstract: There are powerful pathways descending from the auditory cortex (AC) to the inferior colliculus (IC), yet their function is not fully understood. The aim of this study is to examine the effects of a reversible cortical inactivation, achieved by cooling of the AC, on the responses of neurons in the rat IC. Extracellular single-unit or multi-unit activity was recorded in the IC of anaesthetized rats with a 16-channel multielectrode probe introduced along the IC dorso-ventral axis through the dorsal cortex (DCIC) to the central nucleus of the IC (CIC). Cooling of the AC produced an increase in spontaneous activity and magnitude of the sound-evoked response in 47% of the IC neurons. Maximal changes in the neuronal activity were observed in the DCIC and the central part of the CIC. The final segments of the sustained responses to 60 ms stimuli and the off responses were more affected than the onset segments. Inactivation of the AC resulted in a suppression of the post-excitatory inhibition and neuronal adaptation, which was reflected in a pronounced enhancement of synchronized responses to a series of fast repeated clicks. The response parameters recovered, at least partly, to the pre-cooling levels 1 h after the cooling cessation. The frequency tuning properties of the IC neurons did not show any significant changes during the cooling period. The results demonstrate that AC cooling inactivates excitatory corticofugal pathways and results in a less activated intrinsic inhibitory network in the IC.
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic. Electronic address: jpopelar@biomed.cas.cz.
authors.forename: Jiří
authors.initials: J
authors.lastname: Popelář
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic; Department of Medical Biophysics and Informatics, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
authors.forename: Daniel
authors.initials: D
authors.lastname: Šuta
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Lindovský
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic; Department of Electrical Engineering and Computer Science, College of Polytechnics, Jihlava, Czech Republic.
authors.forename: Zbyněk
authors.initials: Z
authors.lastname: Bureš
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic.
authors.forename: Kateryna
authors.initials: K
authors.lastname: Pysanenko
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic.
authors.forename: Tetyana
authors.initials: T
authors.lastname: Chumak
authors.affiliation: Department of Auditory Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Syka
mesh_terms: D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000818:Animals; D001303:Auditory Cortex / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D001306:Auditory Pathways / Q000503:physiopathology; D001833:Body Temperature Regulation; D005072:Evoked Potentials, Auditory; D005260:Female; D059330:GABAergic Neurons / Q000378:metabolism; D007036:Hypothermia, Induced; D007245:Inferior Colliculi / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D009433:Neural Inhibition; D020318:Rats, Long-Evans; D013997:Time Factors
keywords: Auditory cortex; Cooling; Cortical inactivation; Efferent system; Inferior colliculus; Neurons