Frontocentral EEG activity phase predicts subsequent visual target detection in healthy participants but not in schizophrenia

Healthy individuals’ ability to detect visual targets is influenced by the phase of ongoing oscillatory brain activity. Specifically, previous work has found that the phase of 6-10Hz frontocentral electroencephalographic (EEG) activity during the period 300ms-50ms prior to the onset of a visual target differs significantly between hit-trials, in which the participant subsequently detects the target, versus miss trials. This relationship between ongoing brain activity and target detection has not previously been investigated in schizophrenia, although specific deficits in attention and perception are known to occur in the disorder. In the present study, individuals with schizophrenia (n=30) and healthy controls (n=20) performed a visual target detection task while EEG activity was recorded at 1024Hz. We preprocessed the EEG data using standard methods, then performed a time-frequency analysis of the trial epochs using a continuous wavelet transform-based approach. Phase angles were contrasted between hit and miss trials with a bootstrapping technique. In healthy controls, the data clearly replicated published findings, showing a significant phase difference for ongoing 6-10Hz frontocentral brain activity between hit and miss trials beginning about 300ms prior to target onset. However, the schizophrenia group showed no such relationship between the phase of pre-target EEG activity and subsequent target detection. These results demonstrate that the normal relationship between ongoing oscillatory brain activity and visual target detection is disrupted in schizophrenia. This disrupted relationship could contribute to known attentional deficits and perceptual abnormalities in the disorder.