Methods and apparatus for triggering a stimulus for evoked brain response analysis

1 . An input/output adapter for stimulus timing, comprising:

(a) an adapter input port for receiving as input an encoded audio file played from an audio output device, the encoded audio file comprising a first channel carrying trigger data and a second channel carrying stimulus data;

(b) a trigger generation circuit configured to read from the encoded audio file the trigger data in the first channel and generate an output trigger signal;

(c) a stimulus generation circuit configured to read from the encoded audio file the stimulus data in the second channel and generate an output auditory signal;

(d) a trigger output port for receiving the output trigger signal and delivering as output the output trigger signal to an EEG data logger;

(e) an audio output port for receiving the output auditory signal and delivering as output the output auditory signal to an audio playback device; and

(f) a port for receiving power from a power supply for powering the input/output adapter circuitry;

wherein the first channel carrying the trigger data is synchronized with the second channel carrying the stimulus data;

wherein the adapter input port is configured to separate the encoded audio file into the first channel and the second channel and relay the first channel to the trigger generation circuit and simultaneously relay the second channel to the stimulus generation circuit,

wherein the trigger generation circuit is configured to generate the output trigger signal without reading the stimulus data in the second channel, and

wherein the stimulus generation circuit is configured to generate the output auditory signal without reading the trigger data in the first channel.

2 . The input/output adapter of claim 1 , wherein the trigger generation circuit is configured to detect a trigger byte in the trigger data and amplify the corresponding voltage output of the trigger signal to within a voltage range detectable by the EEG data logger.

3 . The input/output adapter of claim 2 , wherein the trigger generation circuit comprises a negative edge detector for detecting the trigger byte in the trigger data.

4 . The input/output adapter of claim 1 , wherein the stimulus generation circuit is configured to recombine the stimulus data into a two-channel output auditory signal comprising a left channel and a right channel, both the left channel and the right channel carrying the output auditory signal.

5 . The input/output adapter of claim 4 , wherein the stimulus generation circuit is configured to electronically amplify the output auditory signal.

6 . The input/output adapter of claim 5 , wherein the stimulus generation circuit is configured to duplicate the stimulus data across the left channel and the right channel.

7 . The input/output adapter of claim 1 , wherein delivery of the output trigger signal to the EEG data logger by the trigger generation circuit of the input/output adapter is synchronized with the delivery of the output auditory signal to the audio playback device by the stimulus generation circuit of the input/output adapter.

8 . An apparatus for stimulus timing of an evoked response, comprising:

(a) a system controller for generating an encoded audio file;

(b) an audio output device for receiving and playing the encoded audio file;

(c) an input/output adapter for receiving the encoded audio file played by the audio output device and simultaneously generating an output auditory signal and an output trigger signal, the input/output adapter comprising:

an adapter input port for receiving as input the encoded audio file played by the audio output device, the encoded audio file comprising a first channel carrying trigger data and a second channel carrying stimulus data;

a trigger generation circuit configured to read from the encoded audio file the trigger data in the first channel and generate the output trigger signal;

a stimulus generation circuit configured to read from the encoded audio file the stimulus data in the second channel and generate the output auditory signal;

a trigger output port for receiving the output trigger signal and delivering as output the output trigger signal to an EEG data logger;

an audio output port for receiving the output auditory signal and delivering as output the output auditory signal to an audio playback device; and

a port for receiving power from a power supply for powering the input/output adapter circuitry;

wherein the first channel carrying the trigger data is synchronized with the second channel carrying the stimulus data;

wherein the adapter input port is configured to separate the encoded audio file into the first channel and the second channel and relay the first channel to the trigger geeration circuit and simultaneously relay the second channel to the stimulus generation circuit,

wherein the trigger generation circuit is configured to generate the output trigger signal without reading the stimulus data from the second channel, and

wherein the stimulus generation circuit is configured to generate the output auditory signal without reading the trigger data from the first channel; and

(d) ERP/EP acquisition hardware, comprising a headset connected for playback of the auditory signal, a plurality of EEG electrodes, and the EEG data logger for receiving EEG data from the plurality of EEG electrodes and the trigger signal from the input/output adapter.

9 . A method for stimulus timing, comprising:

(a) receiving as input an encoded audio file played from an audio output device to a decoder, the encoded audio file comprising a first channel carrying trigger data and a second channel carrying stimulus data;

(b) decoding the encoded audio file into the first channel and the second channel;

(c) based on the trigger data in the first channel and without reading the stimulus data in the second channel, generating an output trigger signal;

(d) based on the stimulus data in the second channel and without reading the trigger data from the first channel, generating an output auditory signal;

(e) delivering as output the output trigger signal to an EEG data logger; and

(f) delivering as output the output auditory signal to an audio playback device;

wherein the first channel carrying the trigger data is synchronized with the second channel carrying the stimulus data;

wherein delivery of the output trigger signal to the EEG data logger is synchronized with the delivery of the output auditory signal to the audio playback device.

10 . The method of claim 9 , comprising detecting a trigger byte in the trigger data and amplifying the corresponding voltage of the output trigger signal to within a voltage range detectable by the EEG data logger.

11 . The method of claim 10 , comprising providing a negative edge detector for detecting the trigger byte in the trigger data.

12 . The method of claim 9 , comprising recombining the stimulus data into a two-channel output auditory signal comprising a left channel and a right channel, both the left channel and the right channel carrying the output auditory signal.

13 . The method of claim 12 , comprising electronically amplifying the output auditory signal.

14 . The method of claim 13 , wherein recombining the stimulus data into a two-channel output auditory signal comprises duplicating the stimulus data across the left channel and the right channel.

15 . A method for stimulus timing, comprising:

(a) receiving as input an encoded file, the encoded file comprising trigger data and stimulus data;

(b) decoding the trigger data and the stimulus data from the encoded file;

(c) based on the decoded trigger data and without reading the decoded stimulus data, generating an output trigger signal;

(d) based on the decoded stimulus data and without reading the decoded trigger data, generating an output stimulus signal;

(e) delivering as output the output trigger signal to a data logger; and

(f) delivering as output the output stimulus signal to a stimulus generator;

wherein the trigger data is synchronized with the stimulus data;

wherein delivery of the output trigger signal to the data logger is synchronized with the delivery of the output stimulus signal to the stimulus generator.

16 . The method of claim 15 , wherein decoding the encoded file comprises separating the encoded file into a first channel carrying the trigger data and a second channel carrying the stimulus data.

17 . The method of claim 16 , wherein the stimulus data is for an auditory stimulus, and the method comprises recombining the stimulus data into a two-channel auditory signal for delivery to the stimulus generator by duplicating the stimulus data across both channels of the two-channel auditory signal.

18 . The method of claim 15 , wherein the trigger data and the stimulus data are encoded on one input channel and decoding the encoded file comprises separating the trigger data and stimulus data from the one input channel.

19 . The method of claim 15 , wherein the trigger data and the stimulus data are each encoded on a corresponding channel of a plurality of channels and decoding the encoded file comprises separating the trigger data and the stimulus data from the plurality of channels.

20 . The method of claim 15 , wherein decoding the encoded file comprises separating the encoded file into a plurality of types of stimulus and a plurality of corresponding triggers.