We used two-photon calcium imaging with single-cell and cell-type resolution. Fear conditioning induced heterogeneous tuning shifts at single-cell level in the auditory cortex, with shifts both to CS+ frequency and to the control CS- stimulus frequency. We thus extend the view of simple expansion of CS+ tuned regions. Instead of conventional freezing reactions only, we observe selective orienting responses towards the conditioned stimuli. The orienting responses were often followed by escape behavior.

• MeSH
• Acoustic Stimulation MeSH
• Behavior, Animal MeSH
• Electroshock MeSH
• Interneurons physiology   MeSH
• Conditioning, Classical physiology   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Neuronal Plasticity physiology   MeSH
• Auditory Cortex physiology   MeSH
• Fear psychology   MeSH
• Learning physiology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

Exposure to loud sounds damages the auditory periphery and induces maladaptive changes in central parts of the auditory system. Diminished peripheral afferentation and altered inhibition influence the processing of sounds in the auditory cortex. It is unclear, however, which types of inhibitory interneurons are affected by acoustic trauma. Here we used single-unit electrophysiological recording and two-photon calcium imaging in anesthetized mice to evaluate the effects of acute acoustic trauma (125 dB SPL, white noise, 5 min) on the response properties of neurons in the core auditory cortex. Electrophysiological measurements suggested the selective impact of acoustic trauma on inhibitory interneurons in the auditory cortex. To further investigate which interneuronal types were affected, we used two-photon calcium imaging to record the activity of neurons in cortical layers 2/3 and 4, specifically focusing on parvalbumin-positive (PV+) and somatostatin-positive (SST+) interneurons. Spontaneous and pure-tone-evoked firing rates of SST+ interneurons increased in layer 4 immediately after acoustic trauma and remained almost unchanged in layer 2/3. Furthermore, PV+ interneurons with high best frequencies increased their evoked-to-spontaneous firing rate ratios only in layer 2/3 and did not change in layer 4. Finally, acoustic trauma unmasked low-frequency excitatory inputs only in layer 2/3. Our results demonstrate layer-specific changes in the activity of auditory cortical inhibitory interneurons within minutes after acoustic trauma.

• Keywords
• broadband noise, calcium imaging, inhibition, interneurons, plasticity,
• MeSH
• Action Potentials MeSH
• Interneurons metabolism   physiology   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Hearing Loss, Noise-Induced physiopathology   MeSH
• Parvalbumins genetics   metabolism   MeSH
• Evoked Potentials, Auditory * MeSH
• Auditory Cortex cytology   physiopathology   MeSH
• Somatostatin genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Parvalbumins MeSH
• Somatostatin MeSH