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Description
Adaptation is a ubiquitous feature of neural responses and has been used extensively to probe cortical tuning properties with non‑invasive methods, particularly fMRI. This approach typically assumes that adaptation reflects fixed sensory tuning. However, neuro‑ and electrophysiological evidence suggests that cortical adaptation may itself be dynamically shaped by stimulus history.Using ultra‑high-field (7T) fMRI, we measured responses to a fixed 3.8‑kHz probe sound following adaptor sounds that varied in frequency. Adaptors were presented either as a single sustained sound or as multiple brief sounds in rapid succession, matched for total duration. Adaptor frequencies spanned values at or below the probe.The two adaptor regimes produced strikingly different adaptation profiles. When adaptors were repeated, maximal adaptation occurred at the probe frequency regardless of voxel preferred frequency. When a single adaptor was used, maximal adaptation occurred at frequencies intermediate between the probe and the voxel’s preferred frequency. Both patterns were captured by a simple linear depletion (Tsodyks–Markram) adaptation model by assuming different effective bandwidths of the adaptation kernel: narrow for repeated adaptors and broad for single adaptors. Importantly, voxel‑level frequency tuning differed little between conditions and was much broader than expected from the macroscopic tonotopic gradient alone, implying substantial local scatter in frequency preference.We propose that such tonotopic scatter—potentially reflecting a property of hypercolumnar organization—enables dynamic, context‑dependent spectral resolution in auditory cortex. From a predictive-coding perspective, the observed sharpening of adaptational tuning following repeated stimulation may reflect increased precision of sensory priors, corresponding to sharpened sensory expectations.