Symposium: Deviance detection along the auditory pathway
Friday, Sep 11, 2015
Adaptation, predictive coding, and perceptual objects in the human auditory system
Neuroscience and Biomed. Eng., Aalto University School of Science, Espoo, Finland
Stimulus-specific adaptation (SSA) of MEG/EEG responses can be used to probe change-detection in the human auditory cortex (AC). By measuring the degree that adaptor stimuli reduce the amplitude (and/or increase the latency) of responses to subsequent probe stimuli as a function of difference on a specific stimulus attribute such as sound frequency, phoneme category, or spatial location, it can be estimated whether the underlying neural populations have specificity to that attribute. Functionally, change-detection also implies predictive coding of the attribute by the neural population. In our previous MEG/EEG SSA, and supporting transcranial magnetic stimulation, studies we have demonstrated that areas anterior and posterior to primary AC process "what" and "where" information in parallel, with responses of the anterior “what” pathway lagging those of the posterior “where” pathway by a few tens of milliseconds. Recently, we have studied where, when, and how information from auditory and visual “what” and “where” pathways is integrated to perceptual objects. In this combined MEG/EEG/MRI study, we again utilized SSA. Subjects viewed two moving audiovisual objects. Identical adaptor-probe sound pairs were linked with visual cues to the same vs. different perceptual object. Based on SSA due to changes in the object that produced the probe sound with respect to the adaptor sound, our results suggest that posterior AC areas initiate and anterior AC areas consolidate associations between sensory events and perceptual objects.