Suppressed Responses to Self-triggered Sounds in the Human Auditory Cortex

Humans are assumed to predict the sensory consequences of their own actions by means of forward models that enable discrimination between self-produced and external sensory signals. Here we tested whether responses in the human auditory cortex would differ to self-triggered versus externally triggered tones. The responses were recorded with a whole-scalp neuromagnetometer from 12 healthy subjects who either themselves triggered a tone by pressing a button once every 5 s or passively listened to externally triggered tones, presented in an identical sound sequence. Sources of the auditory N100m responses, peaking ∼90 ms after sound onset in the supratemporal auditory cortex, were significantly weaker to self-triggered than to externally triggered sounds (suppressions 24 ± 7% and 18 ± 4% in the left and right hemispheres, respectively). These results support the existence of a forward model that predicts the auditory consequences of the subject's own motor acts on the environment — even with a tool — and thereby enables discrimination between self-produced and external sounds.