Low power, wavelet-based spike detector

• US 7,965,779 B2
• Filed: 03/17/2006
• Issued: 06/21/2011
• Est. Priority Date: 03/18/2005
• Status: Expired due to Fees

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: She, Christy L., Harris, John G., Principe, Jose C.
• Primary Examiner(s): Tran; Khai
• Application Number:
  US11/909,060
• Publication Number:
  US 20080247471A1
• Time in Patent Office: 1,922 Days
• Field of Search: 375/242, 375/350, 327/554, 327/94, 327/559, 327/557, 600/546, 600/48, 607/45, 607/59
• US Class Current: 375/242
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: G06F 2218/08 Feature extraction

Abstract

A multi-scale spike detector for performing multi-resolution spike detections of a signal is provided. The spike detector includes a gamma filter having cascaded low-pass filters. The cascaded filters collectively provide different cutoff frequencies, each of the filters having a respective output. One of the filters has an input, at which the signal is received. The spike detector further includes combining circuitry that combines at least some of the respective outputs of the cascaded filters. The differences formed from this combining provide a waveform representation of the input signal. The waveform representation consists essentially of spikes that occur in the signal.

Claims

1. A multi-scale spike detector for performing multi-resolution spike detections of a signal, the spike detector comprising:

a gamma filter having a cascaded plurality of low-pass filters, each of said plurality of filters collectively providing different cutoff frequencies, and each of said plurality of filters having a respective output, and, wherein a first of said plurality of filters has an input, said signal being received at said input; and

combining circuitry combining a plurality of said respective outputs of said plurality of filters, wherein differences formed from said combining provide a waveform representation of said input signal, said waveform representation consisting essentially of spike occurrences in said signal.

2. The spike detector of claim 1, further comprising a resistive line connected to each of said filters, said resistive line supplying to each of said filters a respective bias voltage.

3. The spike detector of claim 2, wherein each bias voltage supplied to one of said filters is different from each other bias voltage supplied to each other of said filters.

4. The spike detector of claim 3, wherein said bias voltages vary linearly from one another.

5. The spike detector of claim 1, wherein each of said low-pass filters is biased by a respective bias voltage to have an exponentially varying cut-off frequency.

6. The spike detector of claim 5, wherein each of said filters has a different cutoff frequency.

7. The spike detector of claim 6, wherein said cutoff frequencies are evenly spaced on a log scale such that a ratio between a center frequency of each filter and a spectrum width of said filter is constant, said gamma filter thus being a constant-Q filter.

8. The spike detector of claim 7, wherein each of said filters comprises a low-pass operational transconductance amplifier (OTA).

9. The spike detector of claim 1, wherein said signal comprises a neural signal coupled to an implanted electrode in a brain of a subject, said implanted electrode being electrically connected to said input of said first filter.

10. A spike detecting system, comprising:

a substrate;

a spike detector disposed on said substrate, said spike detector comprising;

a gamma filter comprising a cascaded plurality of low-pass filters, said plurality of filters collectively providing different cutoff frequencies, each of said filters having a respective output, and a first of said plurality of filters having an input to receive a signal, and combining circuitry combining a plurality of said respective outputs of said plurality of filters, wherein differences formed from said combining provide a waveform representation of said input signal, said waveform representation consisting essentially of spike occurrences in said signal as a binary pulse train, and

a wireless transmitter connected to said spike detector for transmitting said binary pulse train.

11. The system of claim 10, further comprising an RF antenna connected to said transmitter.

12. The system of claim 10, further comprising a multiplexer (MUX) in electrical communication with said spike detector for multiplexing a plurality of signals from multiple electrodes.

13. The system of claim 12, wherein the signals comprise neural signals generated by a neural network.

14. The system of claim 13, wherein the plurality electrodes are connected to the neural network.

15. A method for performing multi-resolution spike detections of a signal, the method comprising:

determining a plurality of cutoff frequencies based upon frequencies of spikes detected wherein the cutoff frequencies respectively define discrete frequency bands with corresponding thresholds; and

determining the presence of at least one spike in each frequency band by comparing the signal to a threshold corresponding each frequency band.

16. The method of claim 15, and wherein differences between adjacent bands are thresholded separately.