Stimulation method for maintaining the responsiveness of electrically excitable cells to repeated electrical stimulation

• US 9,669,213 B2
• Filed: 01/24/2012
• Issued: 06/06/2017
• Est. Priority Date: 01/24/2011
• Status: Active Grant

• Current Assignee: David Tsai, Gregg Jorgen Suaning, John William Morley, Nigel Hamilton Lovell
• Original Assignee: David Tsai, Gregg Jorgen Suaning, John William Morley, Nigel Hamilton Lovell
• Inventors: Lovell, Nigel Hamilton, Tsai, David, Morley, John William, Suaning, Gregg Jorgen
• Primary Examiner(s): Flory, Christopher A
• Application Number:
  US13/981,584
• Publication Number:
  US 20130310899A1
• Time in Patent Office: 1,960 Days
• Field of Search: 607 48, 607 52, 607 53, 607 62, 607 68, 607116
• CPC Class Codes: A61N 1/0543 Retinal electrodes
• CPC Class Codes: A61N 1/36046 of the eye

Abstract

A method of neural stimulation is described for maintaining the responsiveness of electrically excitable cells to repeated electrical stimulation. A stimulating signal (23) is applied to the electrically excitable cells. The stimulating signal is repeatedly applied (26, 29, 32, 35) with a progressively increasing signal strength. A quiescent period (44) may be interleaved between bursts (43, 45) of stimulation. The electrically excitable cells may be retinal cells.

Claims

1. A method of neural stimulation, comprising:

applying a stimulating signal to electrically excitable cells to evoke a response from the electrically excitable cells; and

repeating the application of the stimulating signal with a progressively increasing signal strength by increasing a total electric charge applied to the cells per application to offset fading of response that occurs in the cells on repeated stimulation, wherein the progressively increasing signal strength is based on one or more of;

(i) an earlier conducted calibration that assesses whether responses were successfully maintained during repeated application of the stimulating signal, and (ii) feedback of responses of the electrically excitable cells determined during repeated application of the stimulating signal.

2. A method according to claim 1 wherein increasing the signal strength comprises increasing an amplitude of the stimulating signal.

3. A method according to claim 1 wherein increasing the signal strength comprises increasing a pulse duration of the stimulating signal.

4. A method according to claim 1 wherein increasing the signal strength comprises increasing a number of pulses applied within a specified time period.

5. A method according to claim 1, further comprising:

interleaving repeated applications of the progressively increasing stimulating signal with a quiescent period.

6. A method according to claim 5 wherein the signal strength is reset to an initial value following the quiescent period.

7. A method according to claim 1 wherein the stimulating signal comprises a biphasic pulse having two phases of opposite charge.

8. A method according to claim 7 wherein increasing the signal strength comprises increasing an electric charge of each of the two phases.

9. A method according to claim 7 wherein the two phases of the biphasic pulse are separated by an inter-phase delay.

10. A method according to claim 7 wherein an anodic phase of the biphasic pulse contains a substantially equal and opposite charge to a cathodic phase of the biphasic pulse.

11. A method according to claim 1 wherein one or more parameters define a progression of the progressively increasing signal strength, wherein the earlier conducted calibrating adjusts the one or more parameters to offset the fading of response that occurs in the cells on repeated stimulation.

12. A method according to claim 11 wherein said calibrating comprises:

initialising the one or more parameters;

repeatedly applying the stimulating signal using the one or more parameters;

measuring a response of the cells to the repeated stimulation; and

adjusting the one or more parameters if the response of the cells varies with repeated stimulation.

13. A method according to claim 11 wherein said calibrating comprises:

initialising the one or more parameters;

repeatedly applying the stimulating signal to the cells of a human subject using the one or more parameters;

eliciting an assessment of an evoked response from the human subject; and

adjusting the one or more parameters if the elicited assessment indicates a variation in response of the cells with repeated stimulation.

14. A method according to claim 1 further comprising detecting sensory information, wherein the stimulating signal applied to the electrically excitable cells is dependent on the detected sensory information.

15. A method according to claim 14 wherein the electrically excitable cells comprise retinal neurons and detecting sensory information includes detecting image data.

16. A method according to claim 1 wherein the signal strength of the delivered electric charge within each pulse train increases progressively from the earlier portion of t pulse train to the later portion of the pulse train.

17. A method according to claim 1 wherein:

a first and a second of the two or more pulse trains are separated by a first quiesc period of time; and

the plurality of electrical pulses within each pulse train is separated by at least a second quiescent period of time that is less than the first quiescent period of time.

18. A method of retinal stimulation comprising:

detecting image data;

applying a stimulating signal to electrically excitable retinal cells to evoke a response from the retinal cells, wherein the stimulating signal is dependent on the detected image data; and

repeating the application of the stimulating signal with a progressively increasing signal strength by increasing a total electric charge applied to the retinal cells per application to offset fading of response that occurs in the cells on repeated stimulation.