Apparatus and methods for optical stimulation of neural tissues

Abstract

An apparatus for stimulating a neural tissue of a living subject. The neural tissue is characterized with a thermal diffusion time, T d . The apparatus includes an energy source for generating optical energy and delivering means coupled to the energy source for delivering the generated optical energy to a target neural tissue. The delivering means is configured to in operation deliver the generated optical energy with a radiant exposure that causes a thermal gradient in the target neural tissue, thereby stimulating the target neural tissue, and to deliver the optical energy in pulses with a pulse duration T p such that T p <T d .

What is claimed is: 
     
         1 . An apparatus for stimulating a neural tissue of a living subject, wherein the neural tissue is characterized with a thermal diffusion time, T d , comprising:
 a. an energy source for generating optical energy; and   b. a delivering means coupled to the energy source for delivering the generated optical energy to a target neural tissue,   wherein the delivering means is configured to in operation deliver the generated optical energy with a radiant exposure that causes a thermal gradient in the target neural tissue, thereby stimulating the target neural tissue, and to deliver the optical energy in pulses with a pulse duration T p  such that T p <T d .   
     
     
         2 . The apparatus of  claim 1 , wherein the delivering means comprises:
 a. a connector having a body portion defining a channel extending from a first end to a second end;   b. one or more optical fibers housed in the channel for transmitting the optical energy; and   c. a probe operably coupled to the second end of the connector and having an end portion for delivering the optical energy to a target neural tissue.   
     
     
         3 . The apparatus of  claim 2 , wherein the delivering means further comprises a selecting device operably coupled to the connector for selectively delivering the optical energy through at least one of the one or more optical fibers. 
     
     
         4 . The apparatus of  claim 3 , wherein the delivering means further comprises a movable stage that is operably coupled to the probe such that the probe is movable with the movable stage three-dimensionally to selectively deliver the optical energy to one or more neural fibers of the target neural tissue. 
     
     
         5 . The apparatus of  claim 1 , wherein the delivering means comprises:
 a. a first optical means for directing the optical energy to a desired direction; and   b. a second optical means for focusing the optical energy directed by the first optical means to a target neural tissue,   wherein the first optical means and the second optical means are positioned such that the energy source, the delivering means and the target neural tissue are positioned along an optical path.   
     
     
         6 . The apparatus of  claim 5 , wherein each of the first optical means and the second optical means comprises at least one of one or more optical mirrors, one or more optical lenses, one or more optical couplers, and one or more optical fibers. 
     
     
         7 . The apparatus of  claim 1 , further comprising a controlling means operably coupled to the energy source and the delivering means and the target neural tissue, the controlling means comprising:
 a. a first detector operably coupled to the energy source for measuring the optical energy generated from the energy source;   b. a second detector operably coupled to the target neural tissue for measuring the thermal gradient in the target neural tissue; and   c. a computer operably coupled to the first detector and the second detector for evaluating the optical stimulation of the target neural tissue.   
     
     
         8 . The apparatus of  claim 1 , wherein the energy source comprises a laser capable of generating a beam of optical energy having a wavelength that is fixed or tunable. 
     
     
         9 . The apparatus of  claim 8 , wherein the laser comprises a pulsed infrared laser. 
     
     
         10 . The apparatus of  claim 8 , wherein the laser comprises a free electron laser, an Alexandrite laser, a solid state laser, a CO 2  laser, a tunable optical parametric oscillator (OPO) laser system, an N 2  laser, an excimer laser, a Holmium-doped:Yttrium Aluminum Garnet (Ho:YAG) laser, or an Erbium doped: Yttrium Aluminum Garnet (Er:YAG) laser.