Brain-computer interfaces for communication and control.

The brain's electrical signals enable people without muscle control to physically interact with the world.

Brain-computer interfaces for communication and control

http://www.tmslab.org/tms%20articles%20safety/017.pdf

Risk and safety of repetitive transcranial magnetic stimulation: report and suggested guidelines from the International Workshop on the Safety of Repetitive Transcranial Magnetic Stimulation, June 5–7, 1996

Over the past decade, many laboratories have begun to explore brain-computer interface (BCI) technology as a radically new communication option for those with neuromuscular impairments that prevent them from using conventional augmentative communication methods. BCI's provide these users with communication channels that do not depend on peripheral nerves and muscles. This article summarizes the first international meeting devoted to BCI research and development. Current BCI's use electroencephalographic (EEG) activity recorded at the scalp or single-unit activity recorded from within cortex to control cursor movement, select letters or icons, or operate a neuroprosthesis. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI which recognizes the commands contained in the input and expresses them in device control. Current BCI's have maximum information transfer rates of 5-25 b/min. Achievement of greater speed and accuracy depends on improvements in signal processing, translation algorithms, and user training. These improvements depend on increased interdisciplinary cooperation between neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective methods for evaluating alternative methods. The practical use of BCI technology depends on the development of appropriate applications, identification of appropriate user groups, and careful attention to the needs and desires of individual users. BCI research and development will also benefit from greater emphasis on peer-reviewed publications, and from adoption of standard venues for presentations and discussion.

/pdf/brain-computer-interface-technology-a-review-of-the-first-4t5zj40dij.pdf

Brain-computer interface technology: a review of the first international meeting

Electrical stimulation of excitable tissue: design of efficacious and safe protocols.

Tissue response to potential neuroprosthetic materials implanted subdurally

The relation is investigated between stimulus frequency, stimulus pulse amplitude and the neural damage induced by continuous stimulation of the cat's sciatic nerve. The chronically implanted electrodes were pulsed continuously and the effects of the electrical stimulation were quantified as the amount of early axonal degeneration (EAD) present in the nerves seven days after the continuous stimulation. The primary effect of stimulating at 100 Hz rather than 50 Hz was to cause an increase in the slope of the plot of the amount of EAD versus stimulus lower. There was a small amount of EAD in three of the nerves stimulated at 20 Hz, but there was no detectable correlation between the amount of EAD and the stimulus amplitude. This suggests that continuous electrical stimulation of peripheral nerves at a low frequency induce little or no neural damage, even if the stimulus amplitude is very high. A preliminary presentation of the results has been made elsewhere (Agnew et al., 1993)

Relationship between stimulus amplitude, stimulus frequency and neural damage during electrical stimulation of sciatic nerve of cat.

Chronic microstimulation in the feline ventral cochlear nucleus: physiologic and histologic effects.

In order to use recorded neural activities from the brain as control signals for neuroprosthesis devices, it is important to maintain a stable interface between chronically implanted microelectrodes and neural tissue. Our previous paper introduced a method to quantify the stability of the recording microelectrodes. In this paper, the method is refined 1) by incorporating stereotypical behavioral patterns into the spike sorting program and 2) by using a classifier based on Bayes theorem for assigning the recorded action potentials to the underlying neural generators. An improved method for calculating stability index is proposed. The results for the stability of microelectrode arrays that differ in structure are presented.

Leo A. Bullara

Papers

Tissue response to potential neuroprosthetic materials implanted subdurally

Relationship between stimulus amplitude, stimulus frequency and neural damage during electrical stimulation of sciatic nerve of cat.

Chronic microstimulation in the feline ventral cochlear nucleus: physiologic and histologic effects.

Evaluation of the stability of intracortical microelectrode arrays

Electrical stimulation with Pt electrodes. VII. Dissolution of Pt electrodes during electrical stimulation of the cat cerebral cortex