It's all in the timing: An electrophysiological investigation of the temporal predictions associated with sensory attenuation

Sensory attenuation refers to the reduced phenomenological experience of, and neural response to, self-produced sensations relative to externally generated sensations. Sensory attenuation plays an important role in motor control and in distinguishing between self- and externally generated events. Sensory attenuation is critically dependent on making accurate predictions regarding when self-generated sensory feedback will occur. Previous electroencephalographic (EEG) research on auditory attenuation has shown that we have a ‘default’ temporal expectation for immediate feedback from our actions. This has been indexed by smaller N1 amplitudes (a component of the auditory-evoked potential) to sounds that occur immediately following an action, compared to sounds that are delayed relative to the action. Across four experimental studies, this thesis provides evidence that our temporal expectations regarding the anticipated onset of self-initiated sounds are modifiable with experience. In Chapters 2 to 3, repeated exposure to 100 msec delayed, self-generated tones resulted in a reduction in N1 amplitude across training. This reduction was over-and-above the reduction in N1 associated with repeated exposure to undelayed tones. By the end of training, there was no difference in N1 amplitude between immediate and delayed tones. This suggested that participants’ temporal expectations were somewhat malleable; participants learnt to expect and suppress delayed feedback from their actions, while simultaneously retaining a ‘default’ expectation for immediate feedback. Chapters 4 and 5 revealed that the learned ability to predict and attenuate delayed, self-generated feedback generalised to a different sound (Chapter 4) and possibly to a different context (Chapter 5) to what was experienced during training. Finally, Chapter 6 reported evidence for sensory attenuation deficits in people with schizophrenia/schizoaffective disorder, and further found evidence supporting the fact that these deficits in this clinical population were due to imprecise temporal predictions. Taken together, the results of this thesis provide novel insights into the malleability of temporal expectations and their influence on sensory attenuation. Further, these findings provide a potential, novel avenue for treating the sensory attenuation abnormalities associated with temporal prediction dysfunction in people with schizophrenia/schizoaffective disorder