%0 Journal Article %J Neurosurg Focus %D 2009 %T Evolution of brain-computer interfaces: going beyond classic motor physiology. %A Leuthardt, E C %A Gerwin Schalk %A Roland, Jarod %A Rouse, Adam %A Moran, D %K Brain %K Cerebral Cortex %K Humans %K Man-Machine Systems %K Motor Cortex %K Movement %K Movement Disorders %K Neuronal Plasticity %K Prostheses and Implants %K Research %K Signal Processing, Computer-Assisted %K User-Computer Interface %X

The notion that a computer can decode brain signals to infer the intentions of a human and then enact those intentions directly through a machine is becoming a realistic technical possibility. These types of devices are known as brain-computer interfaces (BCIs). The evolution of these neuroprosthetic technologies could have significant implications for patients with motor disabilities by enhancing their ability to interact and communicate with their environment. The cortical physiology most investigated and used for device control has been brain signals from the primary motor cortex. To date, this classic motor physiology has been an effective substrate for demonstrating the potential efficacy of BCI-based control. However, emerging research now stands to further enhance our understanding of the cortical physiology underpinning human intent and provide further signals for more complex brain-derived control. In this review, the authors report the current status of BCIs and detail the emerging research trends that stand to augment clinical applications in the future.

%B Neurosurg Focus %V 27 %P E4 %8 07/2009 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/19569892 %N 1 %R 10.3171/2009.4.FOCUS0979 %0 Journal Article %J Neurosurg Focus %D 2009 %T Microscale recording from human motor cortex: implications for minimally invasive electrocorticographic brain-computer interfaces. %A Leuthardt, E C %A Zachary V. Freudenberg %A Bundy, David T %A Roland, Jarod %K brain-computer interface %K Electrocorticography %K Motor Cortex %X

OBJECT: 

There is a growing interest in the use of recording from the surface of the brain, known as electrocorticography (ECoG), as a practical signal platform for brain-computer interface application. The signal has a combination of high signal quality and long-term stability that may be the ideal intermediate modality for future application. The research paradigm for studying ECoG signals uses patients requiring invasive monitoring for seizure localization. The implanted arrays span cortex areas on the order of centimeters. Currently, it is unknown what level of motor information can be discerned from small regions of human cortex with microscale ECoG recording.

METHODS: 

In this study, a patient requiring invasive monitoring for seizure localization underwent concurrent implantation with a 16-microwire array (1-mm electrode spacing) placed over primary motor cortex. Microscale activity was recorded while the patient performed simple contra- and ipsilateral wrist movements that were monitored in parallel with electromyography. Using various statistical methods, linear and nonlinear relationships between these microcortical changes and recorded electromyography activity were defined.

RESULTS: 

Small regions of primary motor cortex (< 5 mm) carry sufficient information to separate multiple aspects of motor movements (that is, wrist flexion/extension and ipsilateral/contralateral movements).

CONCLUSIONS: 

These findings support the conclusion that small regions of cortex investigated by ECoG recording may provide sufficient information about motor intentions to support brain-computer interface operations in the future. Given the small scale of the cortical region required, the requisite implanted array would be minimally invasive in terms of surgical placement of the electrode array.

%B Neurosurg Focus %V 27 %8 07/2009 %G eng %U http://dx.doi.org/10.3171/2009.4.FOCUS0980 %N 1 %R 10.3171/2009.4.FOCUS0980