Stimulus-specific adaptation in the inferior colliculus of the mouse: anesthesia and spontaneous activity effects

Brain Struct Funct. 2015 Nov;220(6):3385-98. doi: 10.1007/s00429-014-0862-1. Epub 2014 Aug 13.


Rapid behavioral responses to unexpected events in the acoustic environment are critical for survival. Stimulus-specific adaptation (SSA) is the process whereby some auditory neurons respond better to rare stimuli than to repetitive stimuli. Most experiments on SSA have been performed under anesthesia, and it is unknown if SSA sensitivity is altered by the anesthetic agent. Only a direct comparison can answer this question. Here, we recorded extracellular single units in the inferior colliculus of awake and anesthetized mice under an oddball paradigm that elicits SSA. Our results demonstrate that SSA is similar, but not identical, in the awake and anesthetized preparations. The differences are mostly due to the higher spontaneous activity observed in the awake animals, which also revealed a high incidence of inhibitory receptive fields. We conclude that SSA is not an artifact of anesthesia and that spontaneous activity modulates neuronal SSA differentially, depending on the state of arousal. Our results suggest that SSA may be especially important when nervous system activity is suppressed during sleep-like states. This may be a useful survival mechanism that allows the organism to respond to danger when sleeping.

Keywords: Anesthesia; Auditory; Awake animal; Change detection; Inferior colliculus; SSA; Spontaneous activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation / methods
  • Adaptation, Physiological / physiology*
  • Anesthesia
  • Animals
  • Auditory Cortex / physiology*
  • Cochlear Nerve / physiology
  • Evoked Potentials, Auditory / physiology
  • Inferior Colliculi / physiology*
  • Male
  • Mice
  • Mice, Inbred CBA
  • Wakefulness