Expectation and Attention in Hierarchical Auditory Prediction

Abstract

Hierarchical predictive coding suggests that attention in humans emerges from increased precision in probabilistic inference, whereas expectation biases attention in favor of contextually anticipated stimuli. We test these notions within auditory perception by independently manipulating top-down expectation and attentional precision alongside bottom-up stimulus predictability. Our findings support an integrative interpretation of commonly observed electrophysiological signatures of neurodynamics, namely mismatch negativity (MMN), P300, and contingent negative variation (CNV), as manifestations along successive levels of predictive complexity. Early firstlevel processing indexed by the MMN was sensitive to stimulus predictability: here, attentional precision enhanced early responses, but explicit top-down expectation diminished it. This pattern was in contrast to later, second-level processing indexed by the P300: although sensitive to the degree of predictability, responses at this level were contingent on attentional engagement and in fact sharpened by top-down expectation. At the highest level, the drift of the CNV was a fine-grained marker of top-down expectation itself. Source reconstruction of high-density EEG, supported by intracranial recordings, implicated temporal and frontal regions differentially active at early and late levels. The cortical generators of the CNV suggested that it might be involved in facilitating the consolidation of contextsalient stimuli into conscious perception. These results provide convergent empirical support to promising recent accounts of attention and expectation in predictive coding.

The auditory N1 suppression rebounds as prediction persists over time

“…While we found the auditory N1 to be enhanced under attended conditions, consistent with previous reports on early effects of attention on brain responses (Picton and Näätänen, 1987;Chennu et al, 2013), the effects of attention (i.e., an enhancement) and prediction (i.e., a suppression followed by a rebound) were clearly independent of each other. The independency of the two effects is in line with the findings that repeated sounds are associated with suppressed auditory N1 regardless of attention allocation (Haenschel et al, 2005;Hsu et al, 2014a).…”

Disruption of hierarchical predictive coding during sleep

“…2). This effect has been previously associated with an expectation of the fifth sound in the sequence (40), an interpretation that would appear to contradict the observed disruption of predictions during sleep. However, this ramping-up also can be interpreted as a passive summation of the activation evoked by each successive vowel, without involving top-down expectations.…”

“…2). In the local-global paradigm with awake and conscious subjects, a progressive ramping-up of brain responses across the four sounds has been described and tentatively ascribed to an expectation of the final sound (40). We verified that this ramping-up was present in our data during wakefulness (cluster analysis for slope different from 0, P < 0.001 in temporal areas), and that it diminished during N1 sleep and then N2 sleep (Table S7) while remaining significant (significant slope in N2 sleep, P < 0.001).…”

An introduction to the measurement of auditory event-related potentials (ERPs)

“…First described by Grey Walter et al in 1964 [41], CNV is a sustained negativity that can be observed in between 250-450 ms after the warning stimulus, during the interval in between the warning stimulus and the imperative. CNV is mainly considered to reflect response preparation and it varies with stimulus features, such as intensity, probability, relevance, pitch, and duration (e.g., [42]) as well as attentional engagement [43].…”