BROAD WAVELENGTH PROFILE TO HOMOGENIZE THE ABSORPTION PROFILE IN OPTICAL STIMULATION OF NERVES

• US 20130023960A1
• Filed: 07/21/2012
• Published: 01/24/2013
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Nurotone Medical Ltd.
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Stafford, Ryan C.
• Granted Patent: US 9,011,508 B2
• Time in Patent Office: Days
• US Class Current: 607/88
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/36039 fitting procedures
• CPC Class Codes: A61N 2005/0605 Ear
• CPC Class Codes: A61N 2005/0626 Monitoring, verifying, controlling systems and methods
• CPC Class Codes: A61N 2005/0652 Arrays of diodes
• CPC Class Codes: A61N 2005/0659 infrared
• CPC Class Codes: A61N 5/0622 Optical stimulation for exciting neural tissue
• CPC Class Codes: A61N 5/067 using laser light
• CPC Class Codes: F04C 2270/0421 Controlled or regulated

Abstract

The present invention provides an apparatus that includes an infrared (IR) light source having two or more wavelengths (e.g., a relatively broad wavelength-profile light source and/or a light source with a plurality of relatively narrowband wavelengths), wherein the different wavelengths have different tissue-penetration depths. The IR light provides optical stimulation of nerves to generate nerve-action potentials (NAPs) in one or more individual nerve cells, and/or compound nerve-action potentials (CNAPs) in a nerve bundle. In some embodiments, the stimulation of NAPs and CNAPs is used to restore hearing. In some embodiments, the broad wavelength profile extends the physical volume of tissue that is stimulated, thus homogenizing the spatial light-absorption profile of the stimulation light used, e.g., for optical triggering of NAPs and CNAPs in the cochlea.

Claims

1. A method for optically stimulating a first neural tissue of a person in order to trigger a nerve-action-potential (NAP) response that evokes sensations for the person without damaging the neural tissue, wherein the first neural tissue has a first optical-absorption coefficient at a first optical-absorption wavelength, and wherein applying a first predetermined amount of energy at the first wavelength has a first effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first neural tissue has a second optical-absorption coefficient at a second optical-absorption wavelength, and wherein applying a second predetermined amount of energy at the second wavelength has a second effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first optical-absorption wavelength is different than the second optical-absorption wavelength, the method comprising:

at a first time, generating a first pulsed optical-stimulation signal having optical-signal-energy amounts at a plurality of different wavelengths including the first optical-signal-energy amount at the first optical-absorption wavelength and the second optical-signal-energy amount at the second optical-absorption wavelength, and wherein the second optical-absorption wavelength differs from the first optical-absorption wavelength by at least 5 nm; and

delivering the first pulsed optical-stimulation signal to the first neural tissue of the person, wherein the delivered signal at the first time triggers, in the first neural tissue, one or more nerve-action-potential responses to the signal, and wherein the delivering of the pulsed optical-stimulation signal has a third effectiveness that is greater than the first effectiveness, and greater than the second effectiveness.

2. The method of claim 1, wherein the neural tissue is in an auditory-nerve pathway of the person.

3. The method of claim 1, wherein the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, wherein the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength.

4. The method of claim 1, wherein in the first tissue the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, wherein, at the first time, the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength preferentially triggering one or more NAPS in the first tissue;

and wherein the method further includes;

at a second time, generating a second pulsed optical-stimulation signal having optical-signal-energy amounts at a plurality of different wavelengths including a third optical-signal-energy amount at the first optical-absorption wavelength and a fourth optical-signal-energy amount at the second optical-absorption wavelength; and

delivering the second pulsed optical-stimulation signal to a second neural tissue of the person, wherein in the second tissue the first optical-absorption coefficient at the first wavelength is larger than the second optical-absorption coefficient at the second wavelength, wherein the second pulsed optical-stimulation signal has the third energy amount at the first wavelength and the fourth energy amount at the second wavelength, wherein the third energy amount at the first wavelength is smaller than the fourth energy amount at the second wavelength, and wherein the delivered second pulsed optical-stimulation signal preferentially triggers, in the second neural tissue, one or more nerve-action-potential responses to the signal.

5. The method of claim 1, wherein the first pulsed optical-stimulation signal has a first pulse shape at the first wavelength and a second pulse shape at the second wavelength, wherein the pulse shape of the signal at the first wavelength is different than the pulse shape of the signal at the second wavelength, and wherein pulse shape is defined as the amount of power as a function of time.

6. The method of claim 1, wherein the first pulsed optical-stimulation signal has a first pulse at the first wavelength that starts at a first starting point in time and a second pulse at the second wavelength that starts at a second starting point in time, and wherein the first starting point of the signal at the first wavelength is different than the second starting point of the signal at the second wavelength, and both the first and second pulses contribute to triggering a single NAP or a single CNAP.

7. The method of claim 1, wherein the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, and wherein the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength, and wherein the first wavelength is longer than the second wavelength.

8. An apparatus for optically stimulating a first neural tissue of a person in order to trigger a nerve-action-potential (NAP) response that evokes sensations for the person without damaging the neural tissue, wherein the first neural tissue has a first optical-absorption coefficient at a first optical-absorption wavelength, and wherein applying a first predetermined amount of energy at the first wavelength has a first effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first neural tissue has a second optical-absorption coefficient at a second optical-absorption wavelength, and wherein applying a second predetermined amount of energy at the second wavelength has a second effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first optical-absorption wavelength is different than the second optical-absorption wavelength, the apparatus comprising:

means for, generating, at a first time, a first pulsed optical-stimulation signal having optical-signal-energy amounts at a plurality of different wavelengths including the first optical-signal-energy amount at the first optical-absorption wavelength and the second optical-signal-energy amount at the second optical-absorption wavelength, and wherein the second optical-absorption wavelength differs from the first optical-absorption wavelength by at least 5 nm; and

means for delivering the first pulsed optical-stimulation signal to the first neural tissue of the person, wherein the delivered first pulsed optical-stimulation signal at the first time triggers, in the first neural tissue, one or more nerve-action-potential responses to the first pulsed optical-stimulation, and wherein the delivering of the first pulsed optical-stimulation signal has a third effectiveness that is greater than the first effectiveness, and greater than the second effectiveness.

9. The apparatus of claim 8, wherein the means for delivering the first pulsed optical stimulation signal includes means for delivering the first pulsed optical-stimulation signal to one or more neurons of an auditory-nerve pathway of the person.

10. The apparatus of claim 8, wherein in the first tissue the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, wherein, at the first time, the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength in order to enhance triggering one or more NAPS in the first tissue;

and

wherein the means for generating further includes generating, at a second time, a second pulsed optical-stimulation signal having optical-signal-energy amounts at a plurality of different wavelengths including a third optical-signal-energy amount at the first optical-absorption wavelength and a fourth optical-signal-energy amount at the second optical-absorption wavelength; and

wherein the means for delivering further includes delivering the second pulsed optical-stimulation signal to a second neural tissue of the person, wherein in the second tissue the first optical-absorption coefficient at the first wavelength is larger than the second optical-absorption coefficient at the second wavelength, wherein the second pulsed optical-stimulation signal has the third energy amount at the first wavelength and the fourth energy amount at the second wavelength, wherein the third energy amount at the first wavelength is smaller than the fourth energy amount at the second wavelength, and wherein the delivered second pulsed optical-stimulation signal preferentially triggers, in the second neural tissue, one or more nerve-action-potential responses to the signal.

11. The apparatus of claim 8, wherein the NAPs are compound NAPs (CNAPs), wherein the first neural tissue includes a plurality of tissue types including the first type at a first tissue depth from an emitting interface for the optical-stimulation signal, a second type at a second tissue depth, and a third type at a third tissue depth that has a third optical-absorption coefficient at a third optical wavelength and that is located between the first depth and the second depth, each of the plurality of tissue types having different wavelength-dependent absorption characteristics, and

wherein the means for generating generates light of the first wavelength that is preferentially absorbed by the first type of the neural tissue, and when the first optical-signal-energy amount at the first wavelength has sufficient energy, the first pulsed optical-stimulation signal causes CNAPs in the first type of the neural tissue,

wherein the means for generating generates light of the second wavelength that is preferentially absorbed by the second type of the neural tissue, and when the second optical-signal-energy amount at the second wavelength has sufficient energy, the first pulsed optical-stimulation signal causes CNAPs in the second type of the neural tissue,

wherein if the means for generating the first pulsed optical-stimulation signal were to include generating light having a third wavelength that is preferentially absorbed by the third type of the neural tissue, and if the first pulsed optical-stimulation signal were to have sufficient energy at the third wavelength, then the first optical-stimulation signal would cause CNAPs in the third type of the neural tissue, and

wherein, the means for generating generates, at the first time, the first pulsed optical-stimulation signal that triggers CNAPs at both the first and second depths, but that do not trigger CNAPs at the third depth.

12. The apparatus of claim 8,

wherein the neural tissue is in an auditory-nerve pathway of the person,

wherein the person perceives a dynamic hearing range as a result of the first pulsed optical-stimulation signal at different times,

wherein the person perceives a first perceived sound level at the first time when the first pulsed optical-stimulation signal has a first ratio of optical-signal energy at the first wavelength to optical-signal energy at the second wavelength and has a first total energy at the first time,

wherein the person perceives a second perceived sound level at a second time if the first pulsed optical-stimulation signal has a second ratio of optical-signal energy at the first wavelength to optical-signal energy at the second wavelength and has a second total energy at the second time,

wherein the first ratio is not equal to the second ratio, and

wherein the first and second ratios are chosen to increase the dynamic hearing range perceived by the person.

13. The apparatus of claim 8, wherein the means for generating the pulsed optical-stimulation signal includes a plurality of light sources including a first light source with the first wavelength and a second light source with the second wavelength.

14. The apparatus of claim 8, wherein the means for generating the pulsed optical-stimulation signal further includes generating the optical-stimulation signals using a large-bandwidth light source having a plurality of wavelengths including the first wavelength and the second wavelength, wherein the large-bandwidth source has a spectral bandwidth of at least about 5 nm and no more than about 100 nm.

15. An apparatus for optically stimulating a first neural tissue of a person in order to trigger a nerve-action-potential (NAP) response that evokes sensations for the person without damaging the neural tissue, wherein the first neural tissue has a first optical-absorption coefficient at a first optical-absorption wavelength, and wherein applying a first predetermined amount of energy at the first wavelength has a first effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first neural tissue has a second optical-absorption coefficient at a second optical-absorption wavelength, and wherein applying a second predetermined amount of energy at the second wavelength has a second effectiveness in triggering a nerve-action potential in the first neural tissue, wherein the first optical-absorption wavelength is different than the second optical-absorption wavelength, the apparatus comprising:

an optical generator configured to output, at a first time, a first pulsed optical-stimulation signal having optical-signal-energy amounts at a plurality of different wavelengths including the first optical-signal-energy amount at the first optical-absorption wavelength and the second optical-signal-energy amount at the second optical-absorption wavelength, and wherein the second optical-absorption wavelength differs from the first optical-absorption wavelength by at least 5 nm; and

an optical guide configured to deliver the first pulsed optical-stimulation signal to the first neural tissue of the person, wherein the delivered signal at the first time triggers, in the first neural tissue, one or more nerve-action-potential responses to the signal, and wherein the delivering of the pulsed optical-stimulation signal has a third effectiveness that is greater than the first effectiveness, and greater than the second effectiveness.

16. The apparatus of claim 15, wherein the optical guide is configured to deliver the signal to one or more neurons of an auditory-nerve pathway of the person.

17. The apparatus of claim 15, wherein the optical generator is configured to output the pulsed optical-stimulation signal, wherein the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, and wherein the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength.

18. The apparatus of claim 15, wherein the optical generator is configured to output the first pulsed optical-stimulation signal with a first pulse shape at the first wavelength and a second pulse shape at the second wavelength, wherein the pulse shape of the signal at the first wavelength is different than the pulse shape of the signal at the second wavelength, and wherein pulse shape is defined as the amount of power as a function of time.

19. The apparatus of claim 15, wherein the optical generator is configured to output the first pulsed optical-stimulation signal with a first pulse at the first wavelength that ends at a first ending point in time and a second pulse at the second wavelength that ends at a second ending point in time, wherein the first ending point of the signal at the first wavelength is different than the second ending point of the signal at the second wavelength, and, wherein the optical generator is further configured to output the pulsed optical-stimulation signal with a first spot size at the first wavelength and a second spot size at the second wavelength, wherein the spot size of the signal at the first wavelength is different than the spot size of the signal at the second wavelength.

20. The apparatus of claim 15, wherein the first optical-absorption coefficient at the first wavelength is smaller than the second optical-absorption coefficient at the second wavelength, and wherein the first energy amount at the first wavelength is larger than the second energy amount at the second wavelength, and wherein the first wavelength is longer than the second wavelength.