Music cognition as mental time travel.

As we experience a temporal flux of events our expectations of future events change. Such expectations seem to be central to our perception of affect in music, but we have little understanding of how expectations change as recent information is integrated. When music establishes a pitch centre (tonality), we rapidly learn to anticipate its continuation. What happens when anticipations are challenged by new events? Here we show that providing a melodic challenge to an established tonality leads to progressive changes in the impact of the features of the stimulus on listeners' expectations. The results demonstrate that retrospective analysis of recent events can establish new patterns of expectation that converge towards probabilistic interpretations of the temporal stream. These studies point to wider applications of understanding the impact of information flow on future prediction and its behavioural utility

Subcortical neural synchrony and absolute thresholds predict frequency discrimination independently

The neural mechanisms of pitch coding have been debated for more than a century. The two main mechanisms are coding based on the profiles of neural firing rates across auditory nerve fibers with different characteristic frequencies (place-rate coding), and coding based on the phase-locked temporal pattern of neural firing (temporal coding). Phase locking precision can be partly assessed by recording the frequency-following response (FFR), a scalp-recorded electrophysiological response that reflects synchronous activity in subcortical neurons. Although features of the FFR have been widely used as indices of pitch coding acuity, only a handful of studies have directly investigated the relation between the FFR and behavioral pitch judgments. Furthermore, the contribution of degraded neural synchrony (as indexed by the FFR) to the pitch perception impairments of older listeners and those with hearing loss is not well known. Here, the relation between the FFR and pure-tone frequency discrimination was investigated in listeners with a wide range of ages and absolute thresholds, to assess the respective contributions of subcortical neural synchrony and other age-related and hearing loss-related mechanisms to frequency discrimination performance. FFR measures of neural synchrony and absolute thresholds independently contributed to frequency discrimination performance. Age alone, i.e., once the effect of subcortical neural synchrony measures or absolute thresholds had been partialed out, did not contribute to frequency discrimination. Overall, the results suggest that frequency discrimination of pure tones may depend both on phase locking precision and on separate mechanisms affected in hearing loss

Short-term learning and memory:training and perceptual learning

The frequency-following response (FFR) is a sustained auditory-evoked potential that reflects the phase locking of neurons in the auditory brainstem to periodicities in the waveform of a sound. Studies have shown that short-term auditory training can improve the robustness and/or accuracy of this phase locking. FFR plasticity has been investigated using training tasks that are thought to involve some form of auditory temporal coding, including fundamental-frequency discrimination training, training to identify Mandarin lexical tones, and training to identify speech in noise. The results of these studies have shown that improvements in the trained task are often accompanied by FFR plasticity. This suggests that subcortical auditory processing is not hardwired but can be modified by training even in adulthood. The FFR has also been shown to change following auditory-cognitive training protocols in special populations of listeners who may have subcortical auditory processing deficits, such as children with language-based learning disabilities, elderly listeners, and listeners with sensorineural hearing loss. The results of these studies provide promising evidence that subcortical auditory plasticity could be harnessed to ameliorate auditory processing deficits. It has been hypothesized that this learning-induced subcortical plasticity may be guided by efferent cortical feedback; however, the mechanisms of FFR plasticity remain largely unclear