FIGURE 5. Averaged cerebral blood flow velocity (CBFV) changes of left and right ACA and mean CBFV for both sides during activation in all control subjects and schizophrenics. (A and B) Averaged CBFV changes of left (top) and right (bottom) ACA during cognitive activation (2-back) from 90 s (On) to 170 s (Off) in all healthy control subjects (A) and bilateral (averaged, ACA left and right) CBFV change (B). x-Axis, time (s); y-axis, CBVF (resting CBFV normalized to 1). During activation initial peak, then continuously increasing CBFV, followed by over- and undershoot right after activation (170 s). Regression slope of fitted regression curve of bilateral fTCD signals from 90 to 170 s (from after initial peak to over- and undershoot) was positive: CBFV = 0.9667 + 0.0005 x time. (C and D) Averaged CBFV changes of left (top) and right (bottom) ACA during cognitive activation (2-back) from 90 s (On) to 170 s (Off) in all schizophrenics (C) and bilateral (averaged, ACA left and right) CBFV changes (D). x-Axis, time (s); y-axis, CBVF (resting CBFV normalized to 1). During activation initial peak, then no continuously increasing CBFV but almost slightly decreasing, followed by over- and undershoot right after activation (170 s). Regression slope of fitted bilateral fTCD signals from 95.5 to 170 s was slightly negative: CBFV = 1.0109 - 0.00001 x time. Therefore, temporal behavior of schizophrenic patients under cognitive activation is different from that of control subjects because they show slightly decreasing CBFV during time course of activation, whereas control subjects show significant CBFV increase after initial peak under activation. rel = relative.