Table 1.
Characteristics of the subjects.
Figure 1.
In the BM condition, subjects were instructed to observe mouth-opening movements performed by another individual. Video clips contained 274-ms-long movements over a total of 3,000 ms in one set and were presented silently with an inter-stimulus interval of 3,000 ms. Triggers were provided at the initiation of mouth opening.
Figure 2.
Sequential activation at the brain surface.
Left and Right panels show grand average waveforms (filtered between 1 and 24 Hz with a time window from −100 to 600 ms) measured in a representative normal control (Left) and a representative schizophrenia patient (Right). In order from the top are the 204-channel grand average and the regional (50–52 gradiometers) averages for the left fronto-temporal (green), left parieto-occipital (yellow), right fronto-temporal (blue), and right parieto-occipital (red) areas corresponding to each region in the center panel, which depicts estimated ECDs at the brain surface. Most normal controls exhibited MT/V5 (yellow dot), IPC (red dot)/STS (orange dot), and PMC (blue dot) activation bilaterally, with a total of six areas of activation, while schizophrenia patients had fewer areas of cortical activation. In waveforms from the parieto-occipital regions, fewer components are identified in the schizophrenia patient (Right panel), in contrast to three bilateral components in the normal control (Left panel).
Table 2.
Latencies of estimated ECDs in each region.
Figure 3.
FFT window and peak amplitudes of alpha band oscillation (ABO) and gamma band oscillation (GBO).
The upper and middle panels show averaged FFT distributions between 1–50 Hz for normal controls and schizophrenia patients, respectively. The lower panel shows the mean amplitudes and standard deviations (error bars) of ABO (around 10 Hz; green highlight) and GBO (25 to 40 Hz; orange highlight) in each group. Blue lines and bars denote the Rest condition, while Red lines and bars denote observation the BM condition. In normal controls, the peak amplitude of ABO was suppressed significantly (p<0.001) and GBO was amplified significantly (p<0.001) in the BM condition compared with the control condition. On the other hand, there were no differences between the two conditions for schizophrenia patients. Increased and scattered GBO activity in the Rest condition was also noted in the schizophrenia patients.
Figure 4.
Time frequency representations (TFR) for representative control 1 (and insets for patient 1).
For almost all channels, phase-locking factors (PLF) were observed at latencies of 160 ms throughout the frequency range. Event-related gamma-synchronization (ERS) was also observed in the normal control, mainly in the temporal to parietal regions. The schizophrenia patient exhibited almost the same frequency and latency distributions, except for weaker PLF and ERS predominantly in the right parietal region. Inset, shows TFR of patient 1 from the same channel located in right parietal region, exhibiting absence of these synchronizations.