Learned sound categories leave an attentional imprint in auditory cortex
Learning unfamiliar sounds changed which frequencies listeners' auditory cortex prioritized. In a peer-reviewed experiment, successful learners retained stronger responses to identity-relevant information even when switching to a loudness judgment. The result links category learning with sensory attention, while the selected imaging group and task design leave the mechanism and long-term persistence unresolved.
Science··Morning
The learned priority survives a task change
Frequencies that helped listeners distinguish unfamiliar sound categories elicited stronger responses in auditory cortex after training. That priority persisted when listeners judged the same sounds by loudness, even though the previously useful frequency pattern no longer determined their answer. In this peer-reviewed human experiment, learning left a measurable imprint on the processing of sensory information beyond the task in which it was acquired.[1]
Identical sounds carried different clues
The experiment began with 95 young adults training for five days. Two simultaneous frequency bands carried complex sounds: one contained patterns identifying four pictured aliens, while the other varied without predicting identity. A separate big-or-small judgment depended on overall amplitude. Brain imaging covered 49 successful identity learners, with 20 size-only learners providing a comparison. Researchers also mapped each listener's frequency sensitivity independently, allowing the learned priority to be compared with the cortex's existing organization.[1]
Attention is a supported explanation, with limits
The size-only group lacked the corresponding priority. Among identity learners, responses partly overlapped with a separate task requiring deliberate attention to particular frequencies. This supports acquired attentional gain as an explanation, although brain imaging does not directly measure changes in individual neurons. Carryover between task blocks and other learning-related plasticity remain possible accounts. Because imaging selected successful learners, the result does not describe average learning across the starting group; lifelong persistence and ordinary speech judgments were not established.[1]
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