Thursday, April 29, 2010

Robust and Non-Invasive Way To Tap, Address and Analyze Brain Activity That Is Optimized For Future Brain-Machine Interaction

New York University (New York, NY) and Massachusetts Institute of Technology (Cambridge, MA) scientists in U.S. Patent Application 20100106259 disclose conducting polymer nanowires and methods for their use in a brain-machine interface which is secure, robust and minimally invasive. 

A vascular-based brain-machine interface comprising conducting polymer nanowires is disclosed by a inventors,  Rodolfo R Llinas (New York, NY),  Ian W. Hunter; (Cambridge, MA) and  Bryan P.  Ruddy (Somerville, MA).  The brain-machine interface is based on a nanotechnology/vascular approach which they have developed.  The interface has the advantage of being retrievable in that the nano-scale conducting polymer electrodes are small enough so that even with a large number of electrodes (millions), the interface can be removed without violating the integrity of the brain.

The system for receiving electrical signals from a biological target using vascular-based probes, includes: a plurality of conducting polymer nanowires, each nanowire having a distal end and a proximal end, and an associated probe portion located at the distal end of each nanowire; the plurality of conducting polymer nanowires being delivered into a vascular territory to be monitored; and an electronic interface circuit in electrical communication with the plurality of conducting polymer nanowires, said electronic interface circuit comprising an interface module for interfacing the conducting polymer nanowires with a microwire located in the vicinity of the proximal ends of the conducting polymer nanowires.

When considering the role of neuroscience in modern society, the issue of a brain-machine interface (e.g., between a human brain and a computer) is one of the central problems to be addressed. Indeed, the ability to design and build new information analysis and storage systems that are light enough to be easily carried, has advanced exponentially in the last few years. Ultimately, the brain-machine interface will likely become the major stumbling block to robust and rapid communication with such systems.

To date, developments towards a brain-machine interface have not been as impressive as the progress in miniaturization or computational power expansion. Indeed, the limiting factor with most modern devices relates to the human interface. For instance, buttons must be large enough to manipulate and displays large enough to allow symbol recognition. Clearly, establishing a more direct relationship between the brain and such devices is desirable and will likely become increasingly important.

As the need for a more direct relationship between the brain and machines becomes increasingly important, a revolution is taking place in the field of nanotechnology (n-technology). Nanotechnology deals with manufactured objects with characteristic dimensions of less than one micrometer. It is the inventors' belief that the brain-machine bottleneck will ultimately be resolved through the application of nanotechnology. The use of nanoscale electrode probes coupled with nanoscale electronics seems promising in this regard.

To date, the finest electrodes have been pulled from glass. These microelectrodes have tips less than a micron in diameter and are filled with a conductive solution. They are typically used for intracellular recordings from nerve and muscle cells. A limitation is that activity is recorded from only one cell at a time. It has been possible, however, to obtain recordings from over 100 individual cells using multi-electrode arrays. Nonetheless, this is an invasive procedure as the electrodes are lowered into the brain from the surface of the skull.

The fact that the nervous system parenchyma is permeated by a rich vascular bed makes this space a very attractive area for a brain-machine interface. Gas exchange and nutrient delivery to the brain mass occur in the brain across 25,000 meters of capillaries having diameters of approximately 10 microns. Moving towards the heart, the vessels increase rapidly in diameter with a final diameter of over 20 millimeters.

The NYU/MIT brain interface employs conducting polymers which may be synthesized through electrochemical deposition onto a conductive electrode and manufactured into conducting polymer nanowires and microwires. The conducting polymer nanowire technology coupled with nanotechnology electronics record activity and/or stimulate the nervous system, e.g., brain or spinal cord through the vascular system. The present invention allows the nervous system to be addressed by a large number of isolated conducting polymer nano-probes that are delivered to the brain via the vascular bed through catheter technology used extensively in medicine and particularly in interventional neuroradiology.

In accordance with the NYU/MIT brain interface includes a recording device comprised of a set of conducting polymer nanowires (n-wires) tethered to electronics in a catheter such that they may spread in a "bouquet" arrangement into a particular portion of the brain's vascular system. Such an arrangement can support a very large number of probes (e.g., several million). Each conducting polymer nanowire is used to record the electrical activity of a single neuron, or small group of neurons, without invading the brain parenchyma. An advantage of such a conducting polymer conducting polymer nanowire array is that its small size does not interfere with blood flow, gas or nutrient exchange and it does not disrupt brain activity.

The techniques of the NYU/MIT brain interface are also applicable to the diagnosis and treatment of abnormal brain function. Such technology allows constant monitoring and functional imaging as well as direct modulation of brain activity. For instance, an advanced variation of conventional deep brain stimulation can be implemented in accordance with the present invention by introducing a conducting polymer nanowire or bouquet of nanowires to the area of the brain to be stimulated and selectively directing a current to the area by selectively deflecting the wires and creating longitudinal conductivity.

With the NYU/MIT brain interface, intravascular neuronal recordings can be amplified, processed, and used to control computer interfaces or artificial prostheses. In controlling computational devices, neuronal activity becomes the user input, very much like the manipulation of devices such as keyboards and mice is today. Such input signals could also be used to control the movement of natural limbs that have been separated from their nerve supply through spinal cord or other injury. Thus while direct interface with "intelligent" devices can significantly improve the quality of life for normal individuals, it can also impact disabled individuals, allowing them to be more fully involved in everyday activities.

Obtaining minimally invasive recordings from the brain can also be a useful diagnostic tool in neurology and psychiatry. It provides a functional image of activity deep within the brain that could be localized with precision when combined with MRI. The arrangement of intravascular conducting polymer nano-electrodes in accordance with the present invention can also be used for localized deep brain stimulation without the current need for opening the skull. One advantage of using intravascular conducting polymer nano-electrodes for therapeutic stimulation is that the position of the stimulating electrodes can be easily adjusted. Such adjustment is difficult with the implanted stimulating electrodes used today.

FIG. 2A is an electron micrograph of a conducting polymer microwire having a 15 micron square cross-section with a total length of 20 mm. FIG. 2B is an electron micrograph of a close up image of a conducting polymer microwire having a 15 micron square cross-section with a total length of 20 mm.   

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