Methods and devices for optical stimulation of neural tissues

• US 6,921,413 B2
• Filed: 08/15/2001
• Issued: 07/26/2005
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: Vanderbilt University
• Original Assignee: Vanderbilt University
• Inventors: Mariappan, Karthikeyan, Mahadevan-Jansen, Anita, Konrad, Peter
• Primary Examiner(s): Gibson, Roy D
• Assistant Examiner(s): Johnson, III, Henry M
• Application Number:
  US10/333,700
• Publication Number:
  US 20030208245A1
• Time in Patent Office: 1,441 Days
• Field of Search: 607 88- 93, 607/48, 128/898
• US Class Current: 607/89
• CPC Class Codes: A61B 5/0048 Detecting, measuring or recording by applying mechanical forces or stimuli A61B5/021, A61B5/4884 and A61B9/00 take precedence
• CPC Class Codes: A61N 2005/063 comprising light transmitting means, e.g. optical fibres
• CPC Class Codes: A61N 2005/0659 infrared
• CPC Class Codes: A61N 2005/0665 Reflectors
• CPC Class Codes: A61N 5/0601 Apparatus for use inside the body
• CPC Class Codes: A61N 5/0613 Apparatus adapted for a specific treatment
• CPC Class Codes: A61N 5/0619 Acupuncture
• CPC Class Codes: A61N 5/0622 Optical stimulation for exciting neural tissue
• CPC Class Codes: A61N 5/067 using laser light

Abstract

The present invention provides methods of directly stimulating neural tissue with optical energy. By stimulating neural tissue at wavelengths, laser pulses, and spot sizes disclosed herein, nerve stimulation may be used to uniquely stimulate neural tissue in way not afforded by other means of stimulation. It can allow basic scientists to study the properties of individual neurons or populations of neurons without piercing tissue with fragile microelectrodes. Furthermore, responses of neural tissue can be studied in a pure fashion without contamination by electrical artifact commonly seen with electrical stimulation. With respect to clinical uses, optical stimulation can be used to map function in subsections of peripheral nerves as an aid to operative repair. Finally, stimulation with optical energy does not require physical contact with the nerve which may be an advantage clinically when physical manipulation of neural tissue is not desired.

Claims

1. A method of stimulating neural tissue comprising:

(a) providing a source for generating an optical energy having a wavelength in a range of from two micrometers to six micrometers at an energy output in a range of from 200 microjoules to 5 millijoules;

(b) providing a target neural tissue;

(c) focusing the optical energy on the target neural tissue so that the target neural tissue propagates an electrical impulse, wherein the source comprises a tunable laser.

2. The method of claim 1, wherein the source is pulsed, having each pulse in a range of from 1 picosecond to 10 picosecond micropulse and from 1 microsecond to 10 microsecond macropulse.

3. The method of claim 1, wherein the wavelength is approximately 4.5 micrometers.

4. A method of stimulating a nerve fiber comprising:

(a) providing an optical source capable of generating an optical energy having a wavelength in a range of from one micrometers to eight micrometers at an energy output in a range of from 150 microjoules to 5 millijoules;

(b) providing a target nerve fiber;

(c) focusing the optical energy on the target nerve fiber so that action potentials are propagated, wherein the optical source is pulsed, having each pulse in a range of from 1 picosecond to 10 picosecond micropulse and from 1 microsecond to 10 microsecond macropulse.

5. The method of claim 4, wherein the wavelength is approximately 4.5 micrometers.

6. The method of claim 4, wherein the wavelength is approximately 2.2 micrometers.

7. The method of claim 4, wherein the wavelength is approximately 1.23 micrometers.

8. A method of repeatedly exciting a nerve without damaging the nerve, said method comprising:

(a) providing a laser to generate a laser beam having a wavelength in a range of from two micrometers to nine micrometers at a power output in a range of from 100 microjoules to 5 millijoules, having an area for stimulation with a diameter in a range of from 50 micrometers to 600 micrometers;

(b) providing the nerve;

(c) focusing the laser beam on the nerve so that the nerve conducts a nerve signal;

(d) repeating step (c), wherein the laser is pulsed.