Motor Cortical Brain-Computer Interface for the Paralyzed

A promising application of cortical neuroprostheses is as a Brain-Computer Interface (BCI) that is used to ‘read and translate’ control neural signals from the brain of a paralyzed individual (figure 1). The device will ‘bypass’ the damaged motor pathway of a paralyzed individual (for example an injury or disease of the spinal cord), by interfacing his motor cortex directly with a computer. In collaboration with John Donoghue’s lab at Brown University we are developing an implantable BCI based on the Utah Electrode Array.

Figure 1: Outline of a motor cortical prosthesis

Issues we have been working on here include:

· Optimization of the UEA for recording [1].

· Short and Long-term recording capabilities of the UEA in cortex [2-5].

· Surgical considerations [6].

· Can paralyzed individuals activate their “inactive” motor cortex [7]? Figure 2 illustrates the areas that were activated in the brain of a spinal cord injured volunteer (level C5) when attempting to move his paralyzed right hand, and the fingers on each of his paralyzed legs. The maps were obtained using functional MRI and reflect the significance of signal increase.

Figure 2: Activation resulting from attempted movement

of paralyzed limbs (feet and hand).

· Development of real-time data acquisition systems and interfaces with control systems [8].

· Development of robust automatic algorithms for sorting multi-unit signals from the UEA.

· Investigation of strategies for ‘translating’ the activity of populations of motor cortex neurons [9-11].

· Short-term intra-operative human experimentation.

Bibliography

1. Nordhausen, C.T., P.J. Rousche, and R.A. Normann, Optimizing recording capabilities of the Utah Intracortical Electrode Array. Brain Res, 1994. 637(1-2): p. 27-36.

2. Nordhausen, C.T., E.M. Maynard, and R.A. Normann, Single unit recording capabilities of a 100 microelectrode array. Brain-Res, 1996. 726(1-2): p. 129-40.

3. Maynard, E.M., C.T. Nordhausen, and R.A. Normann, The Utah intracortical Electrode Array: a recording structure for potential brain-computer interfaces. Electroencephalogr-Clin-Neurophysiol, 1997. 102(3): p. 228-39.

4. Maynard, E.M., Studies on the use of a penetrating microelectrode array in a potential motor cortex neuroprosthetic, Department of Department of Bioengineering. 1998, University of Utah: Salt Lake City

5. Rousche, P.J. and R.A. Normann, Chronic recording capability of the Utah Intracortical Electrode Array in cat sensory cortex. J Neurosci Methods, 1998. 82(1): p. 1-15.

6. Maynard, E.M., E. Fernandez, and R.A. Normann, A technique to prevent dural adhesions to chronically implanted microelectrode arrays. J Neurosci Methods, 2000. 97(2): p. 93-101.

7. Shoham, S., et al. functional MRI study of human primary motor cortical representations following traumatic spinal cord injury. in Society for Neuroscience Abstracts. 1997.

8. Guillory, K.S. and R.A. Normann, A 100-channel system for real time detection and storage of extracellular spike waveforms. J Neurosci Methods, 1999. 91(1-2): p. 21-9.

9. Maynard, E.M., et al., Neuronal interactions improve cortical population coding of movement direction. J Neurosci, 1999. 19(18): p. 8083-93.

10. Shoham, S., E. Maynard, and R. Normann. Optimal nonlinear filtering for directionally tuned neurons. in Society for Neuroscience Abstracts. 1999.

11. Shoham, S., et al. New method for nonlinear decoding of neural spike trains. in Society for Neuroscience Abstracts. 2000.