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The N1 auditory ERP and its magnetic counterpart (N1[m]) are suppressed when elicited by self-induced sounds. Because the N1(m) is a correlate of auditory event detection, this N1 suppression effect is generally interpreted as a reflection of the workings of an internal forward model: The forward model captures the contingency (causal relationship) between the action and the sound, and this is used to cancel the predictable sensory reafference when the action is initiated. In this study, we demonstrated in three experiments using a novel coincidence paradigm that actual contingency between actions and sounds is not a necessary condition for N1 suppression. Participants performed time interval production tasks: They pressed a key to set the boundaries of time intervals. Concurrently, but independently of keypresses, a sequence of pure tones with random onset-to-onset intervals was presented. Tones coinciding with keypresses elicited suppressed N1(m) and P2(m), suggesting that action-stimulus contiguity (temporal proximity) is sufficient to suppress sensory processing related to the detection of auditory events.

When individuals share a task with a partner, one's own actions and one's partner's actions have to be precisely tuned to one another. With behavioral means, it has been numerously shown that splitting a simple reaction time task between two participants produces similar interference patterns to those occurring when controlling the whole task on one's own. Less is known about the neuronal correlates when sharing a task with a partner. The processes of agent identification ('my turn' vs. 'my partner's turn') were the focus of this study. In an EEG study, pairs of participants responded to different action-associated stimuli in a Go/NoGo paradigm. The same task was performed together with a partner (joint Go/NoGo condition) and when a partner was not present (single Go/NoGo condition). This study showed a top-down influence of social setting on early visual processing as indexed by the Go-N1 and NoGo-N1 response. This effect was only present in the joint Go/NoGo condition. It was particularly present in those trials where the partner did not have to act. Taken together, these results yield evidence for an early top-down influence of social setting on early processes of stimulus identification and differentiation. [ABSTRACT FROM AUTHOR]

Numerous studies have shown that the N1 event-related potential (ERP) response is attenuated when it is elicited by self-initiated sounds. This N1 suppression effect is generally interpreted to reflect an internal prediction mechanism, which enables the discrimination of the sensory consequences of our own actions and those of others. The blocked design used in the forerunner studies (i.e., self- and externally initiated sounds presented in different blocks) seriously limits the relevance of these findings, because the N1 effect can simply be explained by contextual task differences. In the present study, self- and externally initiated sounds were mixed within blocks. N1 suppression was found, and its magnitude was even larger than that observed in a traditional blocked condition. This result supports the involvement of an internal prediction mechanism in the discrimination of the sensory consequences of one's own actions and those of others. [ABSTRACT FROM AUTHOR]

For several modalities, it has been shown that the processing of sensory information generated by our own actions is attenuated relative to the processing of sensory information of externally generated stimuli. It has been proposed that the underlying mechanism builds predictions about the forthcoming sensory input and forwards them to the respective sensory processing levels. The present study investigated whether early auditory processing is suppressed by the top-down influences of such an internal forward model mechanism. To this end, we compared auditory middle latency responses (MLRs) and evoked 40-Hz responses elicited by self-initiated sounds with those elicited by externally initiated but otherwise identical sounds. In the self-initiated condition, the amplitudes of the Pa (27–33 ms relative to sound onset) and Nb (40–46 ms) components of the MLRs were significantly attenuated when compared to the responses elicited by click sounds presented in the externally initiated condition. Similarly, the evoked activity in the 40-Hz and adjacent frequency bands was attenuated. Considering that previous research revealed subcortical and auditory cortex contributions to MLRs and 40-Hz responses, our results support the existence of auditory suppression effects with self-initiated sounds on temporally and structurally early auditory processing levels. This attenuation in the processing of self-initiated sounds most probably contributes to the optimal processing of concurrent external acoustic events. [ABSTRACT FROM AUTHOR]