title: Responses in Rat Core Auditory Cortex are Preserved during Sleep Spindle Oscillations.
abstract: Sleep is defined as a reversible state of reduction in sensory responsiveness and immobility. A long-standing hypothesis suggests that a high arousal threshold during non-rapid eye movement (NREM) sleep is mediated by sleep spindle oscillations, impairing thalamocortical transmission of incoming sensory stimuli. Here we set out to test this idea directly by examining sensory-evoked neuronal spiking activity during natural sleep.
  
  
  
  We compared neuronal (n = 269) and multiunit activity (MUA), as well as local field potentials (LFP) in rat core auditory cortex (A1) during NREM sleep, comparing responses to sounds depending on the presence or absence of sleep spindles.
  
  
  
  We found that sleep spindles robustly modulated the timing of neuronal discharges in A1. However, responses to sounds were nearly identical for all measured signals including isolated neurons, MUA, and LFPs (all differences < 10%). Furthermore, in 10% of trials, auditory stimulation led to an early termination of the sleep spindle oscillation around 150-250 msec following stimulus onset. Finally, active ON states and inactive OFF periods during slow waves in NREM sleep affected the auditory response in opposite ways, depending on stimulus intensity.
  
  
  
  Responses in core auditory cortex are well preserved regardless of sleep spindles recorded in that area, suggesting that thalamocortical sensory relay remains functional during sleep spindles, and that sensory disconnection in sleep is mediated by other mechanisms.
authors: Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
authors: Yaniv
authors: Y
authors: Sela
authors: Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.
authors: Vladyslav V
authors: VV
authors: Vyazovskiy
authors: Department of Psychiatry, University of Wisconsin-Madison, Madison, WI.
authors: Chiara
authors: C
authors: Cirelli
authors: Department of Psychiatry, University of Wisconsin-Madison, Madison, WI.
authors: Giulio
authors: G
authors: Tononi
authors: Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.|Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors: Yuval
authors: Y
authors: Nir
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001143:Arousal / Q000502:physiology; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials; D008297:Male; D009474:Neurons / Q000502:physiology; D051381:Rats; D011921:Rats, Inbred WKY; D012890:Sleep / Q000502:physiology*
keywords: LFP; NREM sleep; auditory cortex; rat; single-unit; sleep spindles