Specifically, masking auditory inputs with white noise has been shown to reopen the critical period for spectral tuning in the primary auditory cortex (A1). More recently, however, a growing body of evidence has demonstrated that even without peripheral injury or sensory deprivation, the masking of sensory inputs can lead to profound cortical reorganization. 1993) and visual deprivation has been shown to reactivate ocular dominance plasticity in the adult visual cortex ( He et al. Manipulations such as digit amputation, lesions of the retina, or whisker trimming have long been known to drive functional reorganization of adult sensory cortices through deafferentation ( Merzenich et al. 2002 Karmarkar and Dan 2006 Eggermont 2013). The absence of normal sensory inputs, even after the closure of standard critical periods, can induce experience-dependent alterations within sensory cortices ( Trachtenberg et al. Together, these results indicate that the absence of temporal modulation promotes noise-induced plasticity in the adult auditory cortex and suggest an important and continuous role for temporally salient inputs in the maintenance of mature auditory circuits.Īuditory cortex, experience-dependent plasticity, noise exposure, parvalbumin, somatostatin Introduction Detection of c-FOS expression in excitatory and inhibitory cells through post-mortem immunohistochemistry also revealed different patterns of cellular activation depending on modulation depth.
However, this plasticity was fundamentally different in nature for rats exposed to unmodulated noise, as a second passive exposure to pure tones elicited tonotopic reorganization in rats exposed to 0% AM noise only. All exposed rats displayed evidence of cortical plasticity as measured by receptive field bandwidths, tonotopic gradients, and synchronization during spontaneous activity. We tested this hypothesis by passively exposing adult rats to 2 weeks of amplitude-modulated (AM) white noise with different modulation depths from 0% (no modulation) to 100% (strong modulation). Here, we argue that the masking of salient temporal inputs in particular is responsible for changes in neuronal activity that lead to this experience-dependent plasticity. The prolonged masking of auditory inputs with white noise has been shown to reopen the critical period for spectral tuning in the adult rat auditory cortex.
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