ELECTRODES

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority to U.S. provisional patent application no. 62/408,579, filed on October 14, 2016, titled "CONCURRENT TRANSMITTING AND RECEIVING

ELECTROENCEPHALOGRAPH ELECTRODES", which is herein incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

FIELD

[0003] The present application relates to brain stimulation apparatuses (e.g., systems and devices) and methods, particularly, brain stimulation apparatuses (e.g., systems and devices) and methods utilizing concurrent transmitting and receiving electroencephalography electrodes.

BACKGROUND

[0004] It is often desirable to both sense electrical potential and apply electrical stimulation from the same electrodes, including scalp electrodes for EEG recording. For example, treatment of seizures (including epilepsy) and other neurological disorders may benefit from both mapping brain electrical activity and stimulation, such may allow closed-loop stimulation based on EEG feedback. Historically, separate electrodes have been used to record and to stimulate, due to noise and interference between these two systems, as typically sensed signals are many orders of magnitudes lower than applied stimulation signals. In addition, prior art systems typically connect to the patient via a cumbersome multi-wire cable.

[0005] Having separate monitoring and stimulation systems requires two sets of controls and complicates operation as compared to an integrated monitoring and stimulation system with a single control console. Multi-wire cables are a source of unwanted electrical noise and place constraints on patient movement. It is highly desirable to have a combined EEG monitoring and stimulation system.

[0006] For example, it would be particularly beneficial to provide a closed-loop brain stimulation system utilizing electroencephalography (EEG) and transcranial electrical stimulation (TES) system that can provide brain simulation in both healthy subjects and those with a range of psychiatric or neurological disorders using the same set of electrodes for both recording and stimulation, particularly where both recording and stimulation may be performed concurrently. Concurrent EEG monitoring of the effects of TES can provide valuable information, for example, real-time data on the impact of TES on cortical excitability.

[0007] Conventionally, EEG can be used to measures and record the electrical activity of the brain of the subject by using a plurality of electrodes contacting the scalp as shown in FIG. 1 A. For example, the electrodes can be inserted into holders that are the similar in shape and size. FIG. 1 B is a perspective view of a first holder for an EEG electrode. FIG. 1C is another perspective view of the holder for the EEG electrode. FIG. 1C is a cross-section view of the holder for the EEG electrode. The holders are disposed in standardized EEG positions 101 , as shown in FIG. 1A. The preparation is relatively stable, and contact with the scalp is typically accomplished with gels and pastes to bridge the gap between hair and scalp. Although TES can be performed by using electrodes in the standardized EEG positions, historically separate electrodes appropriate for the higher-current TES signal are used, and recording/sensing and stimulating is done at different times. Typically, silver/silver chloride electrodes for TES are high maintenance and the energy transmitted through the electrode must be balanced to prevent degradation.

[0008] For example, in FIGS. 2A-2C, recording using EEG electrodes (shown in FIG. 2A) and TES stimulation (shown in FIG. 2B) may be performed by EEG electrodes or a subset of EEG electrodes in the standardized positions shown. Simultaneous EEG and TES can be performed by replacing some of the recording electrodes 202 with stimulating electrodes on the scalp, leaving the rest as recording electrodes 204, as shown in FIG. 2C. However, this mixing of recording channels and stimulation precludes recording and stimulating at the same site. For example, individualization for participants may cause problems in the conventional scheme. Real estate for recording can be lost. It is difficult to accurately record related brain activity by the conventional method.

[0009] The lack of co-localized EEG and TES electrodes presents challenges for noise cancellation as shown in FIG. 3A and FIG. 3B. For example, estimation of the location and distribution of current sources within the brain based on EEG recordings from the scalp (source localization) is particularly challenging. The spatial temporal nature of EEG requires that the noise from TES electrodes to be modeled (e.g., by ICA, PCA, FEM, minimum norm) in the electrode location and for each individual instead of a direct subtraction. For example, Independent Component Analysis (ICA), Principal Component Analysis (PCA), finite element method (FEM), or minimum norm algorithm can be used to model the noise from TES electrodes. FIG. 3 C is an example of a model to analyze the noise from TES electrodes. But the modeling process is too slow for real-time, closed-loop EEG/TES brain stimulation system. Failure deal with noise effectively interferes with real-time, closed-loop EEG/TES brain stimulation system.

[0010] Thus, there is a need for developing brain stimulation apparatus with concurrent transmitting and receiving EEG electrodes.

SUMMARY OF THE DISCLOSURE

[0011] Described herein are apparatuses and methods for brain stimulation. In general, a brain stimulation apparatus can be used to provide non-invasive brain stimulation, for example, a closed-loop brain stimulation system can provide non-invasive brain stimulation by utilizing electroencephalography (EEG) and transcranial electrical stimulation (TES).

[0012] In general, the brain stimulation apparatus can comprise a plurality of concurrent transmitting and receiving electrodes, referred to herein as concurrent EEG/TES electrodes. The plurality of concurrent transmitting and receiving electrodes can be configured to transmit TES to the scalp and simultaneously receive electrical signals from the scalp to record brain activity of the subject. The EEG electrodes and the TES electrodes are typically unitary (integrated into a whole device) thus

sensing/recording EEG and TES can be co-localized for each electrode. The concurrent transmitting and receiving electrodes can be further configured to get through hair on the scalp. The electrodes can be configured to make connection between the scalp and the brain stimulator with TES/EEG. The electrodes can have low impedance and low maintenance. For example, the electrodes can be inserted into holders that are the similar in shape and size. The preparation can be relatively stable over the course of the experiment. Contact with the scalp can be accomplished with gels and pastes that are integrated into the electrodes themselves to bridge the gap between scalp and a metallic electrical conductors (e.g., silver, or silver/chloride electrode(s)) in the body of the dual EEG/TES electrode. The electrodes can be configured to be minimally messy, despite containing conductive gel/paste, and may be used with additional conductive gel/paste having the same or different electrical conductivity. The co-localization of EEG and TES electrodes can enable noise cancellation schemes. In addition, the electrodes can be cost effective. For example, the electrodes can be reusable or inexpensive for single use.

[0013] In general, concurrent transmitting and receiving electrodes (and particularly EEG/TES concurrent electrodes) for brain electrical sensing and stimulation are disclosed herein. These electrodes can include a first body (portion, region) comprising a first subset of sub-electrodes (first set of conductive paths, which may be columns or tubes of a conductive material, such as a conductive gel or paste) extending to the scalp and a second subset of sub-electrodes (second set of conductive paths, which may be columns or tubes of a conductive material, such as a conductive gel or paste) extending to the scalp. The first subset of conductive paths may be configured to transmit a first overall electrical signal to the scalp (TES); the electrical signal is typically divided between all of the conductive paths, but is applied from a single source (e.g., wire or inner electrode within the body of the EEG/TES electrode). The first and second sets of conductive paths may typically be interspersed (e.g., alternating in a 2D array). The second set of conductive paths may be configured to receive a second overall electrical signal (EEG signal) from the scalp. The first portion (first subset of conductive paths) and the second portion (second subset of conductive paths) can be electrically isolated relative to each other and disposed such that the first transmitted overall electrical signal and the second received overall electrical signal are co- localized to enable direct noise cancellation. For example, the first transmitted overall electrical signal (e.g., TES signal applied) and the first received overall electrical signal (an EEG signal) can be co- localized at the same scalp location; the first subset and the second subset of conductive paths are disposed in an interleaved pattern, very close to each other. [0014] For example, the first subset of conductive paths (e.g., for applying TES) may be configured as columns filled with a conductive gel or paste that extend from a central body region that mates with an electrical input configured to receive input from the TES generator. The columns may be hollow and filled with the conductive gel or paste. The columns may be formed of a polymeric material (e.g., electrically insulative material) and/or may be tapered so that the distal end (to contact the scalp) are narrower in diameter than the proximal end (closer to the central body region). The columns forming the first subset of conductive paths may open into a common region of the central body region so that they may all be placed in electrical contact (via the conductive gel or paste) with an electrical connector adapted to connect to the TES generator. The columns may be all the same dimension (length, diameter, shape, etc.) or they may be different; e.g., the columns in the middle region may be larger in diameter then those in the outer region or vice-versa. An internal stimulating electrode (e.g., silver, silver/silver chloride, etc.) electrode may be included, e.g., between the input and the columns. This internal electrode may be a disk, similar to traditional TES electrodes, or it may be a wire, or the like.

[0015] The second subset of conductive paths (e.g., for recording EEG signals) may also be configured as columns filled with a conductive gel or paste that extend from a central body region that mates with an electrical connection (output) configured to connect to the EEG recorder. The columns may be hollow and filled with the conductive gel or paste. The columns may be formed of a polymeric material (e.g., electrically insulative material) and/or may be tapered so that the distal end (to contact the scalp) are narrower in diameter than the proximal end (closer to the central body region). The columns may be all the same dimension (length, diameter, shape, etc.) or they may be different; e.g., the columns in the middle region may be larger in diameter then those in the outer region or vice-versa. The columns forming the first subset of conductive paths may open into a common region of the central body region so that they may all be placed in electrical contact (via the conductive gel or paste) with an electrical connector adapted to connect to the EEG recorder. An internal electrode (e.g., silver, silver/silver chloride, etc.) electrode may be included, e.g., between the input and the columns. This internal electrode may be a disk, similar to traditional EEG electrodes, or it may be a wire, or the like. The columns forming the first subset and the second subset may be identical in size and shape, or they may be different; similarly, the number of columns in the first subset may be the same as the number in the second subset or they may be different.

[0016] The arrangement of conductive paths ("columns") from the first and second subsets typically overlap so that the approximate 'center' of the stimulation provided by the first subset overlaps and/or is concurrent with the approximate 'center' of the recording provided by the second subset. For example, a center of a first sub-electrode for the first subset and a center of a second sub-electrode for the second subset may be the same, or may be separated by less than 0.5 mm (less than 0.2 mm, less than 0.1 mm, less than 0.08 mm, less than 0.05 mm, less than 0.01 mm, less than 0.005 mm, etc.).

[0017] In general, the concurrent TES/EEG electrodes described herein are wet electrodes, as they use and include a conductive gel, which may be included as part of the electrode (e.g. the conductive columns); additional conductive gel/paste may be used or not. For example, the electrodes may be placed against the scalp using a bias that applies a small amount of force to keep them in position (e.g., less than 0.1 N, less than 0.05N, etc.). Overall, the electrode may have a comb shape, wherein the first portion comprises a first subset of a plurality of tube-like prongs (columns), and the second portion comprises a second subset of the plurality of tube-like prongs (columns). As mentioned, the plurality of tube-like prongs may be a plurality of hollow tube-like prongs filled with a conductive gel.

[0018] The electrode may further include a first electrical connector (electrical input/output) that is electrically connected to the first portion. This first connector may be configured to connect to a stimulator such as a TES stimulator for driving a transcranial electrical stimulation (TES). The electrode can further comprise a second electrical connector (electrical input/output) connected to the second portion, wherein the second connector is connected to an Electroencephalograph (EEG) recorder.

[0019] The electrode can further comprise an adhesive disposed on an exterior surface of the electrode. For example, the first portion and the second portion, including overlapping regions of interleaved conductive columns (prongs) may include an adhesive on the distal end region (e.g., between the prongs).

[0020] Disclosed herein is a electrodes for concurrently recording and stimulating; although these electrodes are described specifically with reference to TES and EEG electrodes, they may alternatively or additional be used for other situation in which combined and concurrent recording and stimulation at the same location is desired; thus, for simplicity these may be referred to as "concurrent TES/EEG electrodes" but may be used in other applications, including in other locations than the scalp.

[0021] The concurrent TES/EEG electrodes described may be used with a stimulation and recording apparatus to simultaneously stimulate and record from a same site(s) of the scalp. The electrode can comprise a comb shape comprising a plurality of tube-like prongs, each of the plurality of prongs extending down to touch the scalp. The brain stimulation apparatus can comprise a first input to the electrode connecting a first subset of the plurality of prongs, and a second input to the electrode connecting to a second subset of the plurality of prongs.

[0022] Any of the electrodes described herein may be used with (or a system including) a noise- cancellation circuitry that separates a received signal such as an EEG signal from an applied signal, such as a TES signal, even when the TES signal is orders of magnitude larger.

[0023] Also described herein are methods for concurrently recording (sensing) and driving

(stimulating) from the same location(s) of a user's scalp. The method can comprise positioning one or more of the electrodes described herein on a subject's scalp, (e.g., an electrode comprising a comb shape comprising a plurality of prongs, each of the plurality of prongs extending down to touch the scalp, where there are two interleaved sets of prongs). The method can further comprise transmitting a first overall electrical signal to the scalp though the first subset of the plurality of prongs, and concurrently (e.g., at the same time) receiving a second overall electrical signal from the scalp by a second subset of the plurality of prongs. The first subset and the second subset interleaved, which allows direct noise cancellation by subtracting the first overall electrical signal from the second first overall electrical signal. [0024] Any of these methods may comprise connecting the first subset of the plurality of prongs to a stimulator for driving a transcranial electrical stimulation (TES) and/or connecting the second subset of the plurality of prongs to an Electroencephalograph (EEG) recorder. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0026] FIG. 1 A illustrates a plurality of EEG electrode arranged in a predetermined pattern (e.g., the 10-20 system or International 10-20 system) to measures and record the electrical activity of the brain of the subject conventionally.

[0027] FIG. 1 B is a top perspective view of a holder for an EEG electrode (traditional holder)

[0028] FIG. 1 C is a bottom perspective view of the holder for the EEG electrode (traditional holder) shown in FIG. IB.

[0029] FIG. ID is a cross-section view of the holder for the EEG electrode (traditional holder) shown in FIG. IB.

[0030] FIG. 2A illustrates an EEG recording performed using stimulation electrodes in standardized positions.

[0031] FIG. 2B illustrates TES stimulation performed by TES electrodes (which may be the same as the EEG electrodes, or may replace the EEG electrodes, shown in FIG. 2A) in standardized positions.

[0032] FIG. 2C illustrates simultaneous EEG and TES can be performed by replacing some of the recording (EEG) electrodes with stimulating (TES) electrodes on the scalp; however simultaneous stimulation and recording is not done in the same locations.

[0033] FIG. 3 A illustrates an example of one arrangement of EEG electrodes and TES electrodes in which the EEG electrodes and TES electrodes are not co-localized.

[0034] FIG. 3B illustrates another example of another arrangement of EEG electrodes and TES electrodes in which the EEG electrodes and TES electrodes are not co-localized.

[0035] FIG. 3C is an example of a model to analyze the noise from TES electrodes.

[0036] FIG. 4A illustrates a cross-sectional view of an example of a concurrent transmitting and receiving (e.g., concurrent TES/EEG) electrode as described herein. The electrode may include a body (formed of a rigid or semi-rigid electrically insulative material) having a comb shape with a plurality of tube-like prongs (shown as tapered prongs with blunted ends) extending down. The prongs are hollow and may be filled with a conductive material (e.g., wet, gel, etc. material) connecting to a wire, as shown in FIG. 6, below.

[0037] FIG. 4B illustrates a perspective view of the concurrent transmitting and receiving electrode in FIG. 4A. [0038] FIG. 4C illustrates another perspective view of the concurrent transmitting and receiving electrode in FIG. 4A.

[0039] FIG. 5 A schematically illustrates a conventionally mixing of recording channels and stimulation (which does not allow concurrent recording and stimulating at the same site).

[0040] FIG. 5B schematically illustrates the use of the concurrent transmitting and receiving electrodes described herein that can be used to enable the continuous recording and transmission of multiple sites (shown schematically as having circles with lines through them), which may allow the use of a noise cancellation scheme to isolate the recorded signals from the transmitted signal.

[0041] FIG. 6 schematically illustrates an example of a concurrent transmitting and receiving electrode as described herein, including a first connection to a TES stimulator (on left) and a second connection to an EEG recorder (on right). The first connector is in electrical communication with a first subset of the columns (shown as tapered columns) via a conductive gel or paste) and the second electrical connector is in electrical contact with the second subset of columns (the first subset and the second subset are entirely electrically isolated from each other within the body of the electrode, which is not shown for simplicity in FIG. 6). The columns of the first subset and the second subset are interleaved with each other,

[0042] FIG. 7 illustrates a block diagram of an example of an electronic circuit for noise cancelling between the received signal (e.g., EEG signal) and transmitted (e.g., TES) signal that is concurrently transmitted and received as described herein. This example shows a noise cancellation regime which is possible because of the virtually identical locations of the stimulation and sensing locations provided as described herein.

[0043] FIG. 8A shows another example showing an exploded view of an electrode assembly (such as those shown in FIGS. 4A-4C and 6) that does co-localized stimulation and recording, as described herein. In FIG. 8 A, the holder holds a TES electrode (shown as a ring electrodeO and an electrode cap, having a central region (opening) into which one or more EEG electrodes may be positioned.

[0044] FIG. 8B is another example showing an exploded view of an electrode assembly that permits co-localized stimulation and recording. In FIG. 8B, the electrode holder holds the TES electrode between two body regions (and upper cap and a lower holder body) and connects to an EEG electrode that passes through the central opening of the TES electrode (or formed between a ring of multiple TES electrodes).

[0045] FIG. 9A shows another exploded view of an electrode assembly that permits co-localized stimulation and recording. FIG. 9B shows the assembly of FIG. 9A assembled. The TES electrode (or a collection of TES electrodes) is/are shown forming a ring with a central opening into which one or more EEG electrode(s) pass. The electrode holder body holds both the TES electrode(s) and the EEG electrode(s) securely in position, though in any of these variations the EEG electrode(s) and/or the TES electrode(s) may be detached separately. DETAILED DESCRIPTION

[0046] The following description of the various embodiments of the invention is not intended to limit the invention to these embodiments, but rather to enable any person skilled in the art to make and use this invention. Disclosed herein are apparatuses, systems and methods for utilizing concurrent transmitting and receiving electroencephalography (EEG) electrodes.

[0047] In general, a brain stimulation apparatus can be used to provide non-invasive brain stimulation, for example, a closed-loop brain stimulation system can provide non-invasive brain stimulation by utilizing electroencephalography (EEG) and transcranial electrical stimulation (TES). In general, TES can be performed by delivering electric currents through a scalp of a subject. Concurrent EEG monitoring of the effects of TES can provide valuable information, for example, real-time data on the impact of TES on cortical excitability.

[0048] A real-time, closed-loop EEG/TES brain stimulation system that handles noise cancellation effectively, may provide concurrent transmitting and receiving electrodes, for example,

electroencephalography electrodes (e.g., "TES/EEG electrodes" or "concurrent TES/EEG electrodes", also referred to herein as "concurrent EEG/TES electrodes" or "EEG/TES electrodes" or simply

"electrodes"). The brain stimulation and recording apparatus can comprise a plurality of concurrent transmitting and receiving electrodes. The plurality of concurrent transmitting and receiving electrodes can be configured to transmit TES to the scalp and at the exact same increment of time (or overlapping time) receive electrical signals from the scalp to record brain activity of the subject. The TES/EEG electrodes co-localize sensing and stimulation. The concurrent transmitting and receiving electrodes can be configured to get through hair to the scalp. The electrodes can be configured to make connection between the scalp and the brain stimulator with TES/EEG. The electrodes can have low impedance and be low maintenance. For example, the electrodes can be connected to one or more wires or cables that connect the combined TES/EEG electrodes to the component stimulator and/or receiver (e.g., each TES/EEG electrode may either include a wire connection to each of the stimulator and sensor/detector, or it may include a connector to couple with a wire for each of the stimulator and sensor). Contact with the scalp can be accomplished without or with additional gels and pastes to bridge the gap between the scalp and the TES/EEG electrode(s). The electrodes are typically wet electrodes that include multiple columns of conductive gel or paste that are open at the distal (scalp-contacting side) to connect to the skin/scalp. As described herein the overlapping co-localization of EEG and TES electrodes can enable noise cancellation schemes.

[0049] In addition, the electrodes can be cost effective. For example, the electrodes can be reusable or inexpensive for single use.

[0050] FIG. 4 A illustrates a cross section view of an example of a concurrent transmitting and receiving electrode. FIG. 4B illustrates a perspective view of the concurrent transmitting and receiving electrode in FIG. 4A. FIG. 4C illustrates another perspective view of the concurrent transmitting and receiving electrode in FIG. 4A. The electrode can be used on the subject's scalp to simultaneously both stimulate and record from the scalp. For example, the electrode can be a wet electrode in some embodiments, wherein the columns 401 are filed with conductive paste or gel. Two subsets of the columns are each in electrical communication in the body of the electrode, with other members of the respective sub-sets, but the two sub-sets are electrically isolated from each other. In FIGS. 4A-4C, the internal structures within the body the pair of conductors that each connect to separate subsets of the columns/prongs 401 are not shown but It would be apparent to one of skill in the art how to partition the body of the electrode appropriately.

[0051] The concurrent transmitting and receiving electrode can be configured to solve the problems with hair and noise cancellation. The electrode can be formed (e.g., printed) with a comb structure to get through the hair as shown in FIGS. 4A-4C. For example, the concurrent transmitting and receiving electrode can comprise a plurality of tube-like prongs and have a "comb" shape. For example, the electrode can comprise a plurality of hollow tube-like prongs. In some embodiments, each of the plurality of tube-like prongs can be filled with a conductive gel and extend down to touch the scalp. The electrode can comprise both conductive and non-conductive materials to produce co-localized recording and stimulating electrodes. The concurrent transmitting and receiving electrode can be EEG electrode in some embodiments. For example, the electrode can be configured to integrate into EEG hardware. For example, the concurrent transmitting and receiving EEG electrode can have a same size as a standard EEG/TES electrode in some embodiments.

[0052] Conventionally, recording is performed by using EEG electrodes and TES stimulation is performed by EEG electrodes or a subset of EEG electrodes in standardized positions at a different time (or using a different set of electrodes at a different time). The methods and apparatuses (devices, systems, etc.) described herein permit simultaneous EEG and TES to be performed by replacing recording electrodes with concurrent TES/EEG electrodes on the scalp. Unlike prior art methods which simply mix recording channels and stimulation channels, precluding recording and stimulating at the same site as shown in FIG. 5A, the concurrent TES/EEG electrodes described herein may be concurrently use to record and stimulate at the same sites in the scalp. In contrast, the traditional EEG measurements when TES stimulation was occurring require sophisticated, computationally intensive/difficult and unreliable methods for removing the noise from TES electrodes by modeling based on the electrode location and for each individual electrode instead of using a direct subtraction as permitted here. For example, such modelling required using ICA, PCA, FE , minimum norm algorithm, etc. and such modeling process may be too slow for real-time, closed-loop EEG/TES brain stimulation systems.

[0053] Co-localized recording and stimulation as made possible by the electrodes described herein can enable a commercial off-the-shelf (COTS) noise cancellation scheme based on acoustic noise cancellation. As shown in FIG. 5B, a concurrent transmitting and receiving electrode can be used to enable the COTS noise cancellation scheme. For example, the TES/EEG electrode can be a wet electrode with both recording and stimulating capabilities. The electrode can comprise both conductive and non- conductive materials to enable co-localized recording and stimulating electrodes. For example, recordings may be EEG recordings, while stimulation may be transcranial electrical stimulation (TES) in some embodiments. [0054] Referring to FIGS. 4A-4C and FIG. 5B, the electrode can comprise a plurality of tube-like prongs. For example, each of the plurality of tube-like prongs can be filled with a conductive gel and extend down to touch the scalp in some embodiments. For example, the electrode can comprise a plurality of combs that overlap but are electrically isolated from each other. Therefore, the electrode can record and stimulate at same site and enable the COTS noise cancellation, for example, subtracting applied current from the received current.

[0055] FIG. 6 illustrates an example of a concurrent transmitting and receiving electrode comprising a first input and a second input while the first input and the second input are interleaved in one embodiment. For example, the electrode can be a comb structure to get through the hair. For example, the electrode can comprise a plurality of tube-like prongs which include a first subset of prongs and a second subset of the prongs. The first input into the electrode body can be electrically connected to the first subset of the prongs and can be connected to a stimulator for driving the TES. The second input to (output from) the electrode body can be connected to the second subset of the prongs and can be connected to the recorder for recording EEG. As shown in FIG. 6, the first input and the second input (output) can be interleaved to enable direct noise cancellation. For example, the first subset of prongs and the second subset of the prongs can be interleaved to enable direct noise cancellation.

[0056] The output and inputs can be positioned at virtually the same region of the scalp to enable co-localized EEG recording and TES stimulation. For example, the first subset of the prongs and the second subset of the prongs can be configured to overlap and are very close together. For example, the overall area of the prongs (e.g., from an outer perimeter of the outer-edge prongs) may be relatively small, with a large density of prongs within them (e.g., between 5 and 100 prongs, greater than 5 prongs, greater than 7 prongs, greater than 9 prongs, greater than 10 prongs, greater than 1 1 prongs, greater than 12 prongs, greater than 15 prongs, greater than 20 prongs, greater than 22 prongs, greater than 25 prongs, greater than 27 prongs, greater than 28 prongs, greater than 30 prongs, etc., and/or less than 150 prongs, less than 140 prongs, less than 130 prongs, less than 120 prongs, less than 1 10 prongs, less than 100 prongs, less than 90 prongs, less than 80 prongs, less than 70 prongs, less than 60 prongs, less than 50 prongs, less than 40 prongs, less than 36 prongs, etc.). For example, the area of the prongs may have a diameter of less than <5mm, <4 mm, <3mm, <2mm, <lmm, <0.8mm, <0.7mm, <0.5mm, etc.

[0057] The overall current/voltage transmitted is distributed between the first subset of the prongs, while the overall current/voltage sensed is distributed between the second subset of prongs. Because the first subset of the prongs and the second subset of the prongs can overlap and individual prongs may be close together, a first equivalent location of the overall current/voltage transmitted and a second equivalent location of the overall current/voltage sensed distributed are the same site, or almost the same site. Therefore, the overall current/voltage transmitted and the overall current/voltage sensed are co- localized. This means that the electrode allow simple separation of transmitted and received signals by direct noise cancellation, for example, by subtracting the applied current from the received current. The COTS acoustic noise cancellation schemes can be used to remove the TES artifact from EEG data. [0058] There may also be an adhesive on the outside of the electrode. Alternatively, the electrode can be held by a head cover (e.g., cap, frame, etc.) to be gently against the scalp, even though the hair.

[0059] In some embodiments, the concurrent transmitting and receiving electrode can comprise a first portion for transmitting and a second portion for receiving. The first portion can comprise a first subset of sub-electrodes and the second portion can comprise a second subset of sub-electrodes. The first portion and the second portion can be extending down to touch the scalp. The first portion and the second portion can overlap. The first portion and the second portion can be disposed interleaved. The first subset of sub-electrodes and the second subset of sub-electrodes can be overlapped and very close to each other. The overall current/voltage transmitted is distributed by the first portion at a first equivalent location. The overall current/voltage sensed is distributed by the second portion at a second equivalent location. The first equivalent location and the second equivalent location are co-localized or almost the same.

Therefore, the electrode is configured to enable simple separation of transmitted and received signals by direct noise cancellation, for example, by subtracting the applied current from the received current.

[0060] FIG. 7 illustrates a block diagram of an electronics module for a concurrent transmitting and receiving electrode. The electrical signals from the EEG electrode and the applied current from the stimulator can go through digital to analog converters (DACs) and a digital signal processing (DSP) unit. The COTS direct noise cancellation can be enabled by subtracting the applied current from the received current. The output can be sent to an EEG amplifier.

[0061] FIGS. 8A-8B and 9A-9B illustrate other examples of concurrent TES/EEG transmitting and receiving electrode assemblies. Any of the features described above in reference to FIGS. 4A-7 may be incorporated or used with/in conjunction with any of these variations,

[0062] In FIG. 8A, the combined or concurrent transmitting and receiving electrode 821 for brain stimulation includes a housing formed from an upper (cap) housing portion 803 and a lower (holder) housing portion 801. The housing may be made of an electrically insulative material, and may be rigid or semi-rigid. An electrode (e.g., TES electrode) or group of electrodes 802 may be sandwiched between the upper and lower housing portions. The TES electrode(s) may be formed into a ring. In some variations the TES electrodes form a first portion comprising a first subset of sub-electrodes that can extend to touch the scalp. This first portion may be configured to transmit a first overall electrical signal (such as a TES signal) to the scalp. In FIG. 8A, one or more sensing (e.g., ECG) electrode(s) 805 may be coupled to the assembled housing. The coupling may be a releasable coupling, and may be secured by a keying that may lock into place (e.g., by rotating), e.g., into the upper housing portion 803. The EEG electrode(s) may then pass through the ring formed by the TES electrode(s). In some variations, the EEG electrodes may form a second portion having a second subset of sub-electrodes that extend to the scalp (e.g., through a ring formed by the first subset of electrodes). The second portion may be configured to receive a second overall electrical signal from the scalp (e.g., EEG). In general, the first portion and the second portion may be electrically isolated and disposed such that the first transmitted overall electrical signal and the second received overall electrical signal are co-localized to enable direct noise cancellation. [0063] FIG. 8B shows another variation of a concurrent transmitting and receiving electrode 851 for brain stimulation includes a housing formed from an upper (cap) housing portion 813 and a lower (holder) housing portion 801. In FIG. 81 1 , the electrode holder region is rounded, but includes one or more notch regions for passing of the electrical connector(s) for the TES electrodes. The housing (either or both components) may be made of an electrically insulative material, and may be rigid or semi-rigid. An electrode (e.g., TES electrode) or group of electrodes 812 may be sandwiched between the upper and lower housing portions. The TES electrode(s) may be formed into a ring. In some variations the TES electrodes form a first portion comprising a first subset of sub-electrodes that can extend to touch the scalp. This first portion may be configured to transmit a first overall electrical signal (such as a TES signal) to the scalp. In FIG. 8B, one or more sensing (e.g., ECG) electrode(s) 815 may be coupled to the assembled housing. The coupling may be a releasable coupling, and may be secured by a keying that may lock into place (e.g., by rotating), e.g., into the upper housing portion 813. The EEG electrode(s) may then pass through the ring formed by the TES electrode(s). In some variations, the EEG electrodes may form a second portion having a second subset of sub-electrodes that extend to the scalp (e.g., through a ring formed by the first subset of electrodes). The second portion may be configured to receive a second overall electrical signal from the scalp (e.g., EEG). In general, the first portion and the second portion may be electrically isolated and disposed such that the first transmitted overall electrical signal and the second received overall electrical signal are co-localized to enable direct noise cancellation.

[0064] FIG. 9A shows yet another example of an exploded view of an assembly forming a concurrent transmitting and receiving electrode 921 for brain stimulation, similar to that shown in FIGS. 8A-8B. In FIG. 9A, the housing includes a keyed upper (cap) region 803 that holds the EEG electrode(s) 905 in a fixed orientation and securely. The EEG electrode(s) may be removable or permanent attached into the assembly. In FIG. 9A, the EEG electrode(s) 905 may be clipped into the housing and held within the opening formed through the TES electrode(s) 902. The region between the EEG electrode(s) bottom and the patient's skin may be filled with a conductive material (e.g., gel). The conductive material may be shared with, or separate and electrically isolated from, the TES electrode(s) 902. The TES electrodes 902 in this example may be sandwiched between the upper 903 and lower housing regions 901. In any of these example the upper region may lock onto the lower region, or it may be removably attached (e.g., by friction fit, keyed fit, snap on connection, etc.). The TES electrode(s) may be held in a predictable distance from the skin (e.g., the base of the housing), or they may be held flush with (or even extend slightly beyond) the bottom surface of the base of the housing 901. In any of the variations described above, the housing may be configured to include a plurality of prongs (e.g., tube-like prongs), as described above. Alternatively or additionally, the electrodes may be flat electrodes. In FIGS. 8A-8B and 9A-9B, the assembly may be characterized as a single-prong electrode. Two, three, or more prongs may be included. For example, the outer ring of TES electrode(s) may be configured as one or more prongs, surrounding the inner one or more prongs forming the EEG electrode(s).

[0065] The systems, devices, and methods of the preferred embodiments and variations thereof can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions are preferably executed by computer- executable components preferably integrated with the system including the computing device configured with software. The computer-readable medium can be stored on any suitable computer-readable media such as RAMs, ROMs, flash memory, EEPROMs, optical devices (e.g., CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component is preferably a general or application- specific processor, but any suitable dedicated hardware or hardware/firmware combination can alternatively or additionally execute the instructions.

[0066] When a feature or element is herein referred to as being "on" another feature or element, it can be directly on the other feature or element or intervening features and/or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. It will also be understood that, when a feature or element is referred to as being "connected", "attached" or "coupled" to another feature or element, it can be directly connected, attached or coupled to the other feature or element or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected", "directly attached" or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or shown with respect to one embodiment, the features and elements so described or shown can apply to other embodiments. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed "adjacent" another feature may have portions that overlap or underlie the adjacent feature.

[0067] Terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. For example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as "/".

[0068] Spatially relative terms, such as "under", "below", "lower", "over", "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another e!ement(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is inverted, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms "upwardly", "downwardly", "vertical", "horizontal" and the like are used herein for the purpose of explanation only unless specifically indicated otherwise. [0069] Although the terms "first" and "second" may be used herein to describe various

features/elements (including steps), these features/elements should not be limited by these terms, unless the context indicates otherwise. These terms may be used to distinguish one feature/element from another feature/element. Thus, a first feature/element discussed below could be termed a second feature/element, and similarly, a second feature/element discussed below could be termed a first feature/element without departing from the teachings of the present invention.

[0070] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or

"approximately," even if the term does not expressly appear. The phrase "about" or "approximately" may be used when describing magnitude and/or position to indicate that the value and/or position described is within a reasonable expected range of values and/or positions. For example, a numeric value may have a value that is +/- 0.1% of the stated value (or range of values), +/- 1% of the stated value (or range of values), +/- 2% of the stated value (or range of values), +/- 5% of the stated value (or range of values), +/- 10% of the stated value (or range of values), etc. Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0071] Although various illustrative embodiments are described above, any of a number of changes may be made to various embodiments without departing from the scope of the invention as described by the claims. For example, the order in which various described method steps are performed may often be changed in alternative embodiments, and in other alternative embodiments one or more method steps may be skipped altogether. Optional features of various device and system embodiments may be included in some embodiments and not in others. Therefore, the foregoing description is provided primarily for exemplar}' purposes and should not be interpreted to limit the scope of the invention as it is set forth in the claims.

[0072] The examples and illustrations included herein show, by way of illustration and not of limitation, specific embodiments in which the subject matter may be practiced. As mentioned, other embodiments may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such embodiments of the inventive subject matter may be referred to herein individually or collectively by the term "invention" merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is, in fact, disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description.