Nonlinear analysis in treatment of intractable epilepsy with EEG biofeedback.

About 25% epilepsy patients are suffering from medically intractable epileptic seizure. Many studies have shown that electroencephalogram (EEG) biofeedback therapy has the exciting potential for seizure control. In this paper, five patients with intractable epilepsy were trained to increase the production of sensorimotor (12~15Hz) activity and decrease the production of slow theta (4~7Hz) activity. Nonlinear analysis are proposed to evaluate the effect of biofeedback training. In all the five patients, the complexity and approximate entropy of EEG increased significantly (P<0.05) after (about 1-month) the biofeedback treatment.

Prosthetic visual acuity in irregular phosphene arrays under two down-sampling schemes: a simulation study.

To investigate the effects of phosphene array irregularity in visual prostheses, a model of phosphenes' positional uncertainty was devised and two different image down-sampling schemes, adapting and non-adapting, were proposed. Based on a simulation system, visual acuity tests were given to four normally sighted subjects under seven degrees of array irregularity and the two down-sampling schemes. With the irregularity index increasing from 0 to 0.6, visual acuity fell over a range of 0.22 logMAR (logarithm of minimum angular resolution) for the adapting scheme and 0.47 logMAR for the non-adapting scheme, both monotonously. Comparison between the two down-sampling schemes was made. For low array irregularity, non-adapting down-sampling afforded higher visual acuity, whereas for higher irregular the adapting approach did. Head movements were observed to play significant roles in the acuity tests.