Anticipatory attention to verbal and non-verbal stimuli is reflected in a modality-specific SPN

The time estimation paradigm allows the recording of anticipatory attention for an upcoming stimulus unconfounded by any anticipatory motor activity. Three seconds after a warning signal (WS) subjects have to press a button. A button press within a time window from 2,850 ms to 3,150 ms after the WS is considered 'correct', a movement prior to 2,850 ms after the WS is labelled 'too early' and a movement after 3,150 ms is labelled 'too late'. Two seconds after the button press a Knowledge of Results (KR) stimulus is presented, informing the subject about the correctness of the response. Stimulus Preceding Negativity (SPN) is a slow wave which is recorded prior to the presentation of the KR stimulus. The SPN has a right hemisphere preponderance and is based upon activity in a network in which prefrontal cortex, the insula Reili and the parietal cortex are crucial. In the present study we asked two questions: (1) does the SPN show modality specificity and (2) does the use of verbal KR stimuli influence the right hemisphere preponderance? Auditory and visual stimuli were presented, in a verbal mode and in a non-verbal mode. SPN amplitudes prior to visual stimuli were larger over the visual cortex than prior to auditory stimuli. SPN amplitudes prior to auditory stimuli were larger over the frontal areas than prior to visual stimuli. The use of verbal stimuli did not influence the right hemisphere preponderance. We concluded that apart from the supramodal effect of KR stimuli in general, there is (first) a modality-specific activation of the relevant sensory cortical areas. The supramodal network underlying the attention for and the use of KR information is activated either from different sensory areas or from language processing cortical areas.