Neural stimulation system and optical monitoring systems and methods

[0001] This application claims the benefit of U.S. Provisional Application No. 60/728,650, filed Oct. 19, 2005, which is incorporated herein by reference in its entirety.

[0002] The present disclosure generally relates to the use of optical monitoring techniques in association with providing neural stimulation to particular target neural populations. More particularly, the present disclosure describes various embodiments of optical monitoring systems, devices, and/or elements that may be used in association with particular neural stimulation systems, devices, and/or elements.

[0003] A wide variety of mental and physical processes are controlled or influenced by neural activity in particular regions of the brain. For example, the neural functions in some areas of the brain (i.e., the sensory or motor cortices) are organized according to physical or cognitive functions. In general, particular areas of the brain appear to have distinct functions in most individuals. In the majority of people, for example, the areas of the occipital lobes relate to vision, the regions of the left interior frontal lobes relate to language, and the regions of the cerebral cortex appear to be consistently involved with conscious awareness, memory, and intellect.

[0004] Many problems or abnormalities with body functions can be caused by dysfunction, damage, disease and/or disorders in the brain. Effectively treating such abnormalities may be very difficult. Epidemiological profiles indicate that the treatment and/or rehabilitation of neurologic dysfunction is extremely challenging due to patient population heterogeneity, for example, due to factors such as age, gender, ethnicity, cause, physiologic location, severity, and time since onset. For most patients exhibiting neurologic damage arising from, for example, a stroke, conventional treatments are not sufficient, and little can be done to significantly improve the function of an affected body part or cognitive function beyond the limited recovery that generally occurs naturally without intervention.

[0005] Optical monitoring may facilitate the evaluation of various types of tissue conditions and/or properties, for example, through near infrared spectroscopy (NIRS). A need exists for neural stimulation systems and methods that include or incorporate particular optical monitoring techniques.

[0006] FIG. 1 is a schematic illustration of a neural stimulation and optical monitoring system configured in accordance with an embodiment of the invention.

[0007] FIG. 2 is a schematic illustration of a neural stimulation and optical monitoring system configured in accordance with another embodiment of the invention.

[0008] FIG. 3 is a schematic illustration of a neural stimulation and optical monitoring system configured in accordance with still another embodiment of the invention.

[0009] FIG. 4 is a schematic illustration of an implantable stimulation and optical controller that may be coupled to an electrode assembly, an optical monitoring assembly, and/or a stimulation and optical monitoring assembly according to an embodiment of the invention.

[0010] FIG. 5 is a schematic illustration of an optical monitoring assembly configured in accordance with an embodiment of the invention.

[0011] FIG. 6A is a schematic illustration of a stimulation and optical monitoring assembly configured in accordance with an embodiment of the invention.

[0012] FIG. 6B is a schematic illustration of a stimulation and optical monitoring assembly configured in accordance with still another embodiment of the invention.

[0013] FIG. 7 is a flow diagram illustrating a process for applying neural stimulation in accordance with an embodiment of the invention.

A. Introduction

[0014] The following disclosure describes various embodiments of neural stimulation and optical monitoring (NSOM) systems. Different types of tissues or substances may absorb, transmit, scatter, reflect, and/or emit optical signals in different manners based upon the optical response characteristics of such tissue or substances. For example, optical signals may be used to detect, monitor, estimate, or measure changes in hemodynamic properties (e.g., fluctuations in oxy-hemoglobin or deoxy-hemoglobin levels, blood volume, or blood flow) and/or other tissue properties, typically in a selective manner. Irradiation of tissues or substances with optical signals having particular characteristics (e.g., single or multiple wavelengths, and/or coherent light) may facilitate the detection, identification, or measurement of specific types of biological information. Systems and methods in accordance with various embodiments of the invention may comprise devices configured for near infrared spectroscopy (NIRS), optical tomography (OT), laser Doppler flowmetry, fluorescence spectroscopy, and/or other optical techniques.

[0015] Depending upon embodiment details, systems in accordance with various embodiments of the present invention may comprise one or more types of neural stimulation devices and/or signal transfer elements configured to apply neural stimulation signals to a set of stimulation sites; and one or more types of optical signal sources, optical signal detectors, and optical signal transfer elements configured to monitor or measure optical signals and/or signal properties at a set of optical monitoring sites.

[0016] Some embodiments may apply or deliver particular types of neural stimulation and/or chemical substances to a patient in association with optical monitoring. A neural stimulation and/or chemical delivery and optical monitoring system (NSCDOMS) may comprise a set of neural stimulation devices configured to provide stimulation signals to a set of stimulation sites; one or more chemical substance infusion or delivery devices (e.g., an implantable drug infusion pump) configured to release or apply one or more chemical substances (e.g., an amphetamine, a pharmacologic agent, a neuroprotective agent, neurotrophic agent, a growth factor, a muscle relaxant, or another substance) to a set of delivery sites upon or within a patient's body; and a set of optical signal sources, detectors, and other optical elements (e.g., optical fibers).

[0017] Particular system embodiments may also include other types of monitoring systems and/or devices for monitoring or measuring patient state signals and/or patient responses, as further described below. Various system embodiments may further comprise hardware and/or software for processing or analyzing neural stimulation, chemical, optical, and/or other types of signals.

[0018] Systems and methods in accordance with various embodiments of the invention may be directed toward restoring, developing, and/or enhancing particular types of neural function, and/or treating or ameliorating neurologic dysfunction. Neurologic dysfunction may include disorders, diseases, injuries, and/or abnormalities related to brain and/or other neural tissue functions. Representative types of neurologic dysfunction may correspond to stroke, traumatic brain injury (TBI), a maladaptive neuroplastic condition, a pain syndrome, auditory disorders (e.g., tinnitus or auditory hallucinations), speech or language disorders (e.g., aphasia), learning disorders (e.g., dyslexia), Parkinson's Disease, essential tremor, and/or one or more other disorders, states or conditions.

[0019] Optical monitoring may facilitate the determination of (1) one or more neural stimulation and/or chemical substance delivery sites; (2) levels (e.g., a peak amplitude), ranges, and/or other characteristics (e.g., a pulse repetition frequency or a modulation pattern) of particular neural stimulation and/or chemical substance delivery parameters; (3) whether neural stimulation and/or a chemical substance therapy is providing an intended or desirable effect; (4) whether to initiate, query, adjust, vary, interrupt, resume, or discontinue neural stimulation and/or a chemical substance therapy, possibly in an adaptive manner; and/or (5) a likelihood that a patient will experience a given or target level of neurofunctional restoration development in association with neural stimulation and/or chemical substance therapy.

[0020] Depending upon embodiment details, neural stimulation may correspond to transcranial, cortical, subcortical, deep brain, cerebellar, spinal column, cranial or other peripheral nerve, and/or other types of neural stimulation. Representative types of neural stimulation that may be employed in particular embodiments include one or more of cortical stimulation (CS), vagal nerve stimulation (VNS), deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS).

[0021] The neural stimulation, substance delivery, and/or optical monitoring may be directed toward one or more anatomical locations. An anatomical location or region at which neural stimulation signals are applied or delivered to, or through, or near a target neural population may be defined as a stimulation site. One or more optical monitoring sites may be external or internal to a patient, and may be essentially identical or proximate or near a stimulation site; or distant or remote from a given stimulation site.

[0022] A stimulation site and/or a target neural population may be identified and/or located in a variety of manners, for example, through one or more procedures involving anatomical landmark identification; structural and/or functional anatomical imaging (e.g., Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging (DTI), functional MRI (fMRI), Positron Emission Tomography (PET), Magnetic Resonance Angiography (MRA), Near-infrared Spectroscopy (NIRS) or Optical Tomography (OT), or Magnetoencephalography (MEG)); electrophysiological signal measurement (e.g., electroencephalography (EEG) or electromyography (EMG)); anatomical spectroscopy (e.g., Magnetic Resonance Spectroscopy (MRS)); and/or other techniques. Representative manners of identifying a target neural population and/or a stimulation site are given in U.S. Pat. No. 7,010,351, which is incorporated herein by reference in its entirety.

[0023] A substance delivery site may correspond, for example, to a target neural population or a target vascular structure. A delivery site may be identified in a variety of manners, for example, through a set of procedures involving anatomical landmark identification and/or medical imaging (e.g., Magnetic Resonance Angiography (MRA)). A representative type of neural stimulation and/or chemical substance infusion system that may be applicable to particular embodiments of the invention is described in U.S. Pat. No. 6,782,292, which is incorporated herein by reference in its entirety. Those of ordinary skill in the relevant art will understand that in general, a substance delivery device may include a control unit, a substance reservoir, an implantable pump unit, and one or more substance delivery elements (e.g., a catheter). The control unit may manage the release or delivery of a substance to particular infusion sites in predetermined amounts at one or more times.

[0024] An optical monitoring site may be determined in association with the identification of a neural stimulation site (e.g., in a manner that corresponds to a type of neural activity measured by fMRI), a substance delivery site, and/or the identification of other anatomical sites of interest, for example, particular vascular structures and/or certain types of neural tissue. Such neural tissue may comprise, for example, neural populations within, proximate to, or having projections associated with a lesion or an infarct penumbra; neoplastic tissue; vascular structures; and/or implanted cells (e.g., at least partially undifferentiated cells such as stem cells). In some embodiments, one or more optical monitoring sites may be associated with multiple brain regions in accordance with a known or standard type of optical monitoring system or device configuration, which may facilitate the acquisition and analysis of optical signals corresponding to a variety of neural functions.

[0025] In various embodiments, the neural stimulation device(s) may apply or deliver stimulation signals to a patient, which may comprise electromagnetic, acoustic, thermal, and/or other types of signals (e.g., mechanical forces) capable of affecting neural function. Electromagnetic stimulation signals may be defined in accordance with spatial, temporal, electrical, and/or magnetic signal parameters, properties and/or characteristics. Such stimulation signals may take on various forms, and may be characterized by various waveform characteristics (e.g., signal amplitude, duration, duty cycle, polarity, pulse width, phase information, pulse repetition frequency, and burst frequency). Spatial, temporal, and/or waveform parameters may be varied in one or more manners to enhance a likelihood of providing, maintaining, or prolonging symptomatic relief from neurologic dysfunction.

[0026] Neural stimulation signals and/or chemical substances may be applied to the patient in association an adjunctive therapy such as a behavioral therapy, which may comprise one or more of physical therapy; physical and/or cognitive skills training or practice, such as training in Activities of Daily Living (ADL); intentional use of an affected body part; speech therapy; vision, visual, and/or spatial perception training; a reading task; a writing task; an auditory activity, for example, a musical or rhythmic task or training; attention tasks; a cognitive activity, memory task, or memory training; comprehension tasks; and/or other therapies or activities.

[0027] Optical signals may be monitored and/or analyzed before, during, and/or after the application of neural stimulation signals and/or chemical substances to the patient. In certain embodiments, based upon particular types of optical signal properties and/or changes therein, the application of neural stimulation signals and/or chemical substances may be initiated, queried, adjusted, interrupted, resumed, and/or discontinued, possibly in an adaptive or generally adaptive manner, which may occur on a real time, near-real time, or delayed basis.

B. Embodiments of Neural Stimulation and Optical Monitoring Systems and Methods for Using Such Systems

[0028] FIG. 1 is a schematic illustration of a neural stimulation and optical monitoring (NSOM) system 1000 according to an embodiment of the invention. In one embodiment, the NSOM system 1000 comprises a neural stimulation system (NSS) 100 and an external optical monitoring system 200. The NSS 100 may comprise an implantable pulse generator (IPG) 110 that is coupled to a set of implanted signal transfer devices, electrode assemblies, and/or electrodes 120. The NSS 100 may also comprise one or more types of signal or substance monitoring devices, for example, an electrode assembly configured to monitor electrocorticographic (ECoG) signals. Depending upon embodiment details, the NSS 100 may comprise fully implanted components that are surgically placed within a patient 10, as illustrated; and/or components that are partially implanted or external to the patient 10.

[0029] The NSS 100 may further comprise an external programming or communication device 130, which in some embodiments facilitates unidirectional or bi-directional signal transfer (e.g., through magnetic or RF telemetry) involving the IPG 110. Such communication may involve the transfer of configuration information, program instructions, stimulation signal parameters, power signals, and/or data. The communication device 130 may be coupled to a programming device 140 (e.g., a personal digital assistant (PDA) or a handheld, laptop, or desktop computer) by a wire-based or a wireless link 135.

[0030] An optical monitoring system 200 may comprise a system for applying optical signals to and detecting optical signals scattered within or reflected by living tissue. Such a system may involve near infrared spectroscopy or optical topography. In one embodiment, the optical monitoring system 200 comprises at least one optical source/detector pair 210 carried by a monitoring structure 220; and a control/analysis unit 250. Some embodiments may comprise multiple source/detector pairs 210 carried by a single or multiple monitoring structures 220. In certain embodiments the optical monitoring system 200 may be configured for wireless or wire-based signal transfer with the programming device 140; or the communication device 130 may be coupled to the optical monitoring system 200 in an embodiment that omits the programming device 140. In a representative embodiment, the optical monitoring system 200 comprises an imagent™ functional brain imaging system and/or an OxiplexTS™ tissue oximeter, both of which are commercially available from ISS, Inc., of Champaign, Ill.

[0031] FIG. 2 is a schematic illustration of an NSOM system 1010 according to an embodiment of the invention. In one embodiment, the NSOM system 1010 comprises an IPG 110; a set of electrode assembles or electrode devices 120 configured to receive and apply neural stimulation signals; a communication device 120; an optical monitoring assembly 310; and an optical monitoring and programming device (OMPD) 300. In some embodiments, an IPG 110 may be implanted at an above-neck location rather than at a subclavicular location as shown in FIGS. 1 and 2.

[0032] The communication device 130 may be configured for wireless signal transfer to and/or from the IPG 110, and may be coupled to or carried by the OPMD 300. In one embodiment, the communication device 130 is coupled to the OPMD 300 by a link 135. The optical monitoring assembly 310 may be configured for monitoring optical signals at one or more external locations on the patient's anatomy, and may be configured for wireless or wire-based communication with the OPMD 300. In one embodiment, the optical monitoring assembly 310 may be coupled to the OPMD 300 by a link 315.

[0033] The optical monitoring assembly 310 may comprise a set of optical sources, a set of optical detectors, and electrical and/or optical signal transfer elements, for example, in a manner described in detail by Alper Bozkurt et al. in “A portable near infrared spectroscopy system for bedside monitoring of newborn brain,” BioMedical Engineering Online 2005, 4:29, which is incorporated herein by reference in its entirety. The optical sources and detectors may be carried by one or more support members 312, which may be positioned at desired monitoring locations (e.g., upon a patient's head or scalp).

[0034] The OPMD 300 comprises a device such as a PDA or a handheld, laptop, or desktop computer having hardware and software configured to (1) direct the generation and detection of optical signals; (2) process and/or analyze the detected signals; (3) visually indicate (e.g., by way of a display device and/or a graphical user interface) detected, estimated, or measured optical signal properties and/or physiologic or physiologic correlate properties associated therewith; (4) direct the specification or selection of neural stimulation parameters, which may include waveform, spatial, and/or temporal parameters; and/or (5) communicate with the IPG 110 to facilitate or effectuate the transfer or exchange of neural stimulation parameters and/or other information (e.g., patient data; or measured, sampled, or stored ECoG signals).

[0035] The optical monitoring, signal processing, and/or information presentation functionality of the OPMD 300 may be implemented in a manner that is essentially identical, analogous, or similar to that described by Bozkurt et al. In some embodiments, the OPMD 300 may be configured for wireless or wire-based communication with a computer system 800 to facilitate certain types of signal processing, analysis, and/or characterization operations. In certain embodiments, the communication device 130 and the optical monitoring assembly 310 may be integrated into or carried by a single housing or structure, which may be handheld or adapted for wearing or carrying by the patient 10.

[0036] FIG. 3 is a schematic illustration of an NSOM system 1020 according to another embodiment of the invention. In one embodiment, the NSOM system 1020 comprises an implantable stimulation and optical monitoring controller (ISOMC) 400 that is coupled to a set of electrode assemblies or devices 120, a set of optical monitoring assemblies (OMAs) 460, and/or a set of stimulation and optical monitoring assemblies (SOMAs) 480 by way of one or more links 435. Depending upon a type of device under consideration, a link 435 may comprise one or more lead wires and/or optical fibers to provide pathways for electrical and optical signals. An electrode assembly 120 may be implanted epidurally or subdurally. Depending upon embodiment details, an OMA 460 or a SOMA 480 may be implanted subcutaneously, epidurally, or subdurally.

[0037] In some embodiments, multiple OMAs 460 and/or SOMAs 480 may be implanted at or relative to different, possibly distant, brain locations. Such brain locations may be in the same or different brain hemispheres, such that noise or certain types of background activity that may affect detected optical signal properties may be subtracted from or otherwise compensated for relative to signals detected by particular OMAs 460 and/or SOMAs 480 under consideration with respect to desired brain locations.

[0038] Additionally or alternatively, optical signals detected in association with an OMA 460 and/or a SOMA 480 implanted relative to a first brain location may be used to (1) determine whether to apply, modify, or discontinue neural stimulation in a different brain area, and/or (2) select or identify one or more neural stimulation parameters in accordance with which neural stimulation will be applied in a different brain area. For example, in a representative embodiment, one OMA 460 may detect particular hemodynamic properties associated with neural activity in a healthy brain region, while another OMA 460 or a SOMA 480 detects hemodynamic properties associated with neural activity in a homologous brain region that exhibits a type of neurologic dysfunction, for example, a maladaptive neuroplastic condition (e.g., tinnitus or a central pain syndrome). Based upon a difference or relationship between detected optical signals corresponding to such brain regions, the application of neural stimulation signals to the brain region exhibiting neurologic dysfunction may be initiated, continued, varied, interrupted, resumed, or discontinued.

[0039] The NSOM system 1020 further comprises a communication device 530 that is configured for wireless or wire-based signal transfer with an external stimulation and optical monitoring programming device (SOMPD) 500. The communication device 530 may be coupled to the SOMPD 500 by a link 535. The communication device 530 is also configured for wireless communication with the ISOMC 400, such that neural stimulation parameters, optical monitoring parameters, and optical monitoring signals or results may be communicated between the SOMPD 500 and the ISOMC 400.

[0040] In various embodiments, the SOMPD 500 may (1) direct the selection of neural stimulation and/or optical monitoring instructions, commands, and/or parameters, and their issuance to the ISOMC 400; (2) receive, process, and/or analyze signals or information received from the ISOMC 400; (3) visually indicate neural stimulation information; (4) visually indicate detected, estimated, or measured optical signal properties and/or physiologic or physiologic correlate properties associated therewith; and/or (5) perform different or additional functions. Depending upon embodiment details, the SOMPD 500 may comprise a PDA or a handheld or other type of computer. Particular signal processing and/or information presentation functionality provided by the SOPMD 500 may be implemented in a manner that is essentially identical, analogous, or similar to that described above with respect to the OPMD 300.

[0041] FIG. 4 is a schematic illustration of an ISOMC 400 that may be coupled to an electrode assembly 120, an OMA 460, and/or a SOMA 480, and/or individual light emitting and/or light detecting devices (e.g., individual fibers or a set of fibers, which may possibly have microlens, wavelength filtering, and/or light directing elements coupled thereto) according to an embodiment of the invention. In one embodiment, the ISOMC 400 comprises a power source 402, a pulse generator 410, an electrical signal I/O unit 420, an optical signal input/output (I/O) unit 430, a signal processing unit 440, and a control and communication unit 450. The power source 402 may comprise a battery, a capacitor, and/or another type of energy storage device. The power source 402 may be rechargeable in certain embodiments. The pulse generator 410 may comprise circuitry for generating and outputting neural stimulation signals in accordance with spatial, temporal, and/or waveform parameters.

[0042] The electrical signal I/O unit 420 may comprise circuitry for interfacing electrical signal transfer elements such as lead wires, electrical contacts or electrodes, electrode devices, and/or electrode assemblies 120 to (1) the pulse generator 410; (2) signal storage elements, such as an electronically writable, configurable, or programmable medium; and/or (3) the signal processing unit 440 in a manner understood by those skilled in the art.

[0043] The optical signal I/O unit 430 may comprise one or more types of light emitting and light detecting devices, which may include one or more of a light emitting diode (LED), a semiconductor laser, and a photodetector. The optical signal 1/O unit 430 may additionally comprise one or more types of optical elements such as wavelength filters, beam splitters, electrical and/or optical multiplexors, and/or micromechanical optical switches. Additionally, the optical signals I/O unit 430 may comprise particular types of signal modulation elements, in a manner understood by those skilled in the art.

[0044] In various embodiments, the optical signal I/O unit 430 may include multiple light emitting devices, each of which is configured to generate light centered at a particular wavelength and/or having a desired bandwidth. The optical signal I/O unit may also include multiple light detecting devices in a corresponding manner. Depending upon embodiment details, the optical signal I/O unit 430 may activate subsets of sources and detectors at one or more times (e.g., in a time multiplexed manner), which may facilitate power conservation. In certain embodiments, NIRS may be facilitated by multiple infrared LEDs or semiconductor lasers operating at optical wavelengths that may be particularly affected by hemodynamic properties. In an alternate embodiment, light emitting devices (e.g., LEDs) may output light in the ultraviolet (UV) spectrum to facilitate fluorescence spectroscopy measurements (e.g., based upon wavelength dependent fluorescence intensity differences exhibited by different tissue types, such as healthy tissue versus neoplastic tissue).

[0045] One representative type of device that may be suitable for particular embodiments of the ISOMC 400 is described by Eiji Higurashi et al., in “An Integrated Laser Blood Flowmeter,” Journal of Lightwave Technology, Vol. 21, No. 3, Mar. 2003, which is incorporated herein by reference in its entirety. Another type of device that may be suitable for particular ISOMC embodiments is described by S. Shinohara et al., in “Laser Doppler velocimeter using the self-mixing effect of a semiconductor laser diode,” Applied Optics, Vol. 25, No. 9, p. 1417-1419, May 1986, which is incorporated herein by reference in its entirety.

[0046] The signal processing unit 440 may comprise an analog and/or digital signal processing device for performing operations such as signal filtering; noise compensation; mathematical operations and/or signal analysis associated with intensity, power, spectral, and/or phase characteristics of detected optical signals; and/or other operations that may involve generated and/or detected optical signals (e.g., monitoring self-mixing behavior.

[0047] The control and communication unit 450 may comprise (1) a processing unit and associated circuitry for directing or managing the application of neural stimulation signals and the detection and processing of optical signals, and (2) telemetric communication circuitry that directs or manages signal transfer with the communication device 530. Such signal transfer may involve the transfer of measured or processed optical monitoring signals, such that they may be analyzed by an external device (e.g., the SOMPD 500 or other device).

[0048] In some embodiments, optical monitoring operations may occur on a periodic, intermittent, or specifically requested basis in order to conserve power. In some embodiments, the control and communication unit 450, the SOMPD 500, and/or another device may determine one or more neural stimulation parameters based upon detected and/or processed optical signals, and possibly initiate, adjust, vary, query, interrupt, resume, or discontinue the application of neural stimulation signals based upon such detected or processed signals.

[0049] In certain embodiments, an ISOMC 400 may comprise, be based upon, and/or utilize one or more elements described in U.S. Pat. Nos. 5,520,190 and 5,601,611, both of which are incorporated herein by reference in their entireties.

[0050] Also shown in FIG. 4 is an OMA 460 according to an embodiment of the invention. In one embodiment, the OMA 460 comprises a support member or structure 464 configured to carry a set of optical emission elements 466 and a set of optical detection elements 468. In various embodiments, an optical emission element 466 and/or an optical detection element 468 may comprise a set of optical fibers, possibly coupled to a lens or microlens; a wavelength filter; and/or another type of optical signaling element (e.g., a MEMS device). The optical fibers may be coupled to the optical I/O unit 430. In some embodiments, one or more portions of the support member or structure 464 may carry blocking, shielding, or filtering elements (e.g., an optically opaque, absorbing, or blocking material, coating, or layer) through which undesirable optical signals (e.g., optical signals originating external to the patient 10) that may affect optical monitoring operations.

[0051] The emission and detection elements 466, 468 may be positioned relative to each other in a manner that facilitates the detection of optical signals that are scattered, reflected, and/or emitted (e.g., in association with fluorescence) by target tissues, which may reside proximate to and/or somewhat distant from a monitoring site. In a representative embodiment, particular emission and detection elements 466, 468 may be separated from each other by approximately 0.5 cm to approximately 5.0 cm, or approximately 1.5 cm to approximately 3.5 cm, or approximately 2.0 cm to 3.0 cm.

[0052] Depending upon embodiment details and/or particular target tissues under consideration, optical signals detected by an OMA 460 may correspond or generally correspond to a target monitoring region 470. A target monitoring region 470 may be defined or approximately defined based upon a type of optical signal path through tissue, which may correspond to a modified Beer-Lambert law. In a representative embodiment, an OMA 460 may be implemented in a manner analogous to that described in U.S. Pat. No. 5,024,226, which is incorporated herein by reference in its entirety.

[0053] FIG. 5 is a schematic illustration of an OMA 462 according to another embodiment of the invention. The OMA 462 of FIG. 5 comprises emission elements 466 and detection elements 468 exhibiting a different configuration than that shown in FIG. 4, and which may facilitate monitoring corresponding to multiple target monitoring regions 470a-h.

[0054] Also shown in FIG. 4 is a SOMA 480 according to an embodiment of the invention. In one embodiment, the SOMA 480 comprises a support member or structure 464 configured to carry a set of electrical contacts or electrodes 122, a set of optical emission elements 466, and a set of optical detection elements 468. The electrodes 122 may be coupled to the electrical signal I/O unit 420 by a set of lead wires 124, and the optical emission and detection elements 466, 468 may be coupled to the optical signal I/O unit 430. A target monitoring region 470 may correspond to tissue located between, beneath, and/or proximate to one or more electrodes 122.

[0055] FIG. 6A is a schematic illustration of a SOMA 481 according to another embodiment of the invention. In one embodiment, the SOMA 481 comprises a set of electrodes 122, optical emission elements 466, and optical detection elements 468 configured in a manner that establishes or approximately establishes one or more optical signal phase relationships between emission and detection elements 466, 468. For instance, a set of optical emission elements 466 and a set of optical detection elements 468 may be positioned, organized, or arranged to form a phased optical array. Such phase relationships may be relevant to phase cancellation optical signal analysis as described by Britton Chance et al., in “A novel method for fast imaging of brain function, non-invasively, with light,” Optics Express, Vol. 2, No. 10, 11 May 1998, p. 411-423, which is incorporated herein by reference in its entirety.

[0056] FIG. 6B is a schematic illustration of a SOMA 482 according to another embodiment of the invention. In one embodiment, the SOMA 482 comprises a set of electrodes 122, optical emission elements 466, and optical detection elements 468 configured in a manner that establishes multiple target monitoring regions 470. Many other types of support member, electrode, emission element, and/or detection element configurations are possible in accordance with various embodiments of the present invention.

[0057] In some embodiments, a SOMA 480, 481, 482 may omit one or more optical detection elements 468, such that optical signals output by particular optical emission elements 466 carried by the SOMA may be detected by one or more optical signal detection devices that are external to the patient (e.g., proximate to the patient's skull).

[0058] In certain embodiments, an ISOMC 400, an electrode assembly 120, an OMA 460, and/or a SOMA 480 may be implemented using peg- or screw-type structures, for example, in a manner that is identical and/or analogous to that described in U.S. patent application Publication No. US 2005/0075680, incorporated herein by reference in its entirety, and U.S. Pat. No. 5,024,226.

[0059] FIG. 7 is a flow diagram of a process 600 for neural stimulation in association with optical monitoring according to an embodiment of the invention. Process 600 may contain various process portions, particular aspects of which are described in detail hereafter.

[0060] Process portion 610 can include identifying one or more neural stimulation and/or optical monitoring sites, and process portion 620 can include implanting a set of neural stimulation and possibly optical monitoring devices in a patient 10. Process portion 630 can include monitoring optical signals in patient tissue, for example, within or relative to one or more brain regions. Process portion 640 can include applying neural stimulation to the patient at one or more stimulation sites, in accordance with particular neural stimulation parameters. Process portion 650 can include monitoring optical signals in patient tissue, some of which may have been exposed to or affected by neural stimulation signals.

[0061] Process portion 660 can include determining whether to adjust or vary neural stimulation, possibly based upon particular optical monitoring signals and/or processed information associated therewith. In the event that neural stimulation is to be adjusted or modified, process portion 670 can include determining an adjusted, modified, or updated set of stimulation parameters, possibly based upon particular optical monitoring signals and/or processed information associated therewith. Process portion 640 may subsequently apply neural stimulation in accordance with the updated stimulation parameters. Adjustment of neural stimulation parameters populations may occur in a real-time, approximately real-time, or delayed manner. Process portion 680 can include determining whether to interrupt or discontinue neural stimulation, in which case process portion 690 can include discontinuing neural stimulation and possibly optical monitoring operations.

[0062] In other embodiments, a process 600 may be directed toward neural stimulation and/or chemical substance delivery in association with optical monitoring. One or more of the previously described process portions may involve the application, variation, interruption, or cessation of chemical substance delivery based upon monitored optical signals and/or processed information generated from such signals, in a manner that may or may not depend upon the application of neural stimulation to one or more target neural populations.

[0063] From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. For example, certain aspects of the systems and methods described above may be automated or partially automated, and may be implemented on computer systems and/or via computer-readable media. In particular embodiments, aspects of the stimulation site selection procedure and/or the evaluation procedure can be automated in such a fashion. Further, in some embodiments, data obtained from a first neural population can be used to identify signal delivery parameters for a second neural population of the same patient. In other embodiments, data obtained from stimulating one type of neural population in one patient can be used to at least influence the choice of signal delivery parameters selected for a different type of neural population in a different patient. Aspects of the invention described in the context of particular embodiments may be combined or eliminated in other embodiments. Although advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages. Additionally, none of the foregoing embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims.