ABSTRACT
This study explored the accuracy of using visual evoked potentials (VEP) technology for visual acuity estimation. The enrolled 726 patients with post-traumatic unilateral decrease in visual acuity included the injured eyes served as the experimental group, and the healthy eyes as the control group. The least signal visual angle (LSVA), and amplitude and latency of P100 were chosen as test indexes. The results under different experimental conditions were recorded by PRVEP technology. All data collected were processed and analyzed by SPSS software. The results showed that the coincidence between subjective and VEP visual acuity was 96.7% in control group, but there was very significant difference in experimental group. It was concluded that with the regression formulation for the amplitude of P100 and vision under LSVA, visual acuity can be estimated more accurately and impartially.
ABSTRACT
This study explored the possibility of using event-related potentials (ERP) for the measurement of picture-recognition memory and examined its correlation with the Chinese Wechsler Memory Scale-revised (WMS-RC) in patients with memory disorder caused by severe traumatic brain injury (sTBI). The subjects included 20 sTBI patients with memory disorder and 22 healthy individuals. Memory function was measured by using WMS-RC. Behavioral and ERP responses were recorded on-line during performance on a battery of picture recognition and the responses were analyzed off-line for recognition memory effects. Mean memory quotient (MQ) of patients with sTBI was significantly lower than that of the control group. Mean reaction time (RT) was significantly longer and the mean correctness rate (CR) of picture recognition was significantly lower in sTBI group than that of the controls. In controls, the main components of average ERP of picture recognition includes two positive-going waves, designated as P170 and P500, that appear 170 ms and 500 ms after stimulation when the subject could later successfully recall and recognize the pictures. P500 amplitude of target stimulus was significantly higher than that of non-target stimulus. Compared to controls, P500 responses of sTBI group were significantly delayed in latency (P<0.001) and lower in amplitude (P<0.001). P500 latency showed significant negative correlation with MQ and the scores of "addition", "visual recognition", "picture recall", "visual reproduction" and "tactile memory" in WMS-RC. ERP of picture recognition provides a neurophysiological approach to directly assess memory impairment, and P500 may serve as a helpful index for memory disorder caused by sTBI in forensic practice.