ULTRA NEUROMODULATION TECHNIQUES

BACKGROUND

[0001] The subject matter disclosed herein relates to neuromodulation and more specifically, to techniques for modulating a physiological response using energy applied from an energy source.

[0001] Neuromodulation has been used to treat a variety of clinical conditions. For example, electrical stimulation at various locations along the spinal cord has been used to treat chronic back pain. Such treatment may be performed by an implantable device that periodically generates electrical energy that is applied to a tissue to activate certain nerve fibers, which in turn may result in a decreased sensation of pain. In the case of spinal cord stimulation, the stimulating electrodes are generally positioned in the epidural space, although the pulse generator may be positioned somewhat remotely from the electrodes, e.g., in the abdominal or gluteal region, but connected to the electrodes via conducting wires. In other implementations, deep brain stimulation may be used to stimulate particular areas of the brain to treat movement disorders, and the stimulation locations may be guided by neuroimaging. Such central nervous system stimulation is generally targeted to the local nerve or brain cell function and is mediated by electrodes that deliver electrical pulses and that are positioned at or near the target nerves. However, positioning electrodes at or near the target nerves is challenging. For example, such techniques may involve surgical placement of the electrodes that deliver the energy. In addition, specific tissue targeting via neuromodulation is challenging. Electrodes that are positioned at or near certain target nerves mediate neuromodulation by triggering an action potential in the nerve fibers, which in turn results in neurotransmitter release at a nerve synapse and synaptic communication with the next nerve. Such propagation may result in a relatively larger or more diffuse physiological effect than desired, as current implementation of implanted electrodes stimulate many nerves or axons at once. Because the neural pathways are complex and interconnected, a more targeted modulated effect may be more clinically useful.

BRIEF DESCRIPTION

[0002] Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed subject matter, but rather these embodiments are intended only to provide a brief summary of possible embodiments. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0003] In one embodiment, a modulation system is provided that includes an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and a controller configured to: spatially select the region of interest; focus the energy on the region of interest; and adjustably control repeated application of the energy via the energy application device to the region of interest to induce repeated preferential activation of a subset of the synapses within a predefined time, the subset being located in the region of interest, to cause a persistent change to one or more molecules of interest after the repeated application of energy.

[0004] In another embodiment, a modulation system is provided that includes an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and a controller configured to: spatially select the region of interest; focus the energy on the region of interest; and repeatedly control application of the energy via the energy application device to the region of interest to induce preferential activation of a subset of the synapses within a predefined time, the subset being located in the region of interest, to cause a persistent change to one or more molecules of interest after the repeated application of energy.

[0005] In another embodiment, a system for treating diabetes in a subject is provided that includes an ultrasound energy application device configured to apply an ultrasound dose regimen to an internal organ; and a controller adapted to control the ultrasound energy

application device to apply the ultrasound dose regimen, wherein the ultrasound dose regimen comprises a plurality of energy doses applied at separate time points within a time window of the ultrasound dose regimen.

[0006] In another embodiment, a modulation system is provided that includes an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and a controller configured to: spatially select the region of interest; focus the energy on the region of interest; and repeatedly control application of the energy via the energy application device to the region of interest to apply a low duty-cycle energy dose regimen to the region of interest, wherein the low duty-cycle dose regimen comprises a plurality of electrical stimulations that are separated by an adjustable off period of at least 4 hours, wherein the off period is determined at least in part on feedback received by the controller.

[0007] In another embodiment, a method for treating a subject having a metabolic disorder is provided that includes applying an ultrasound dose regimen to an internal organ of the subject having the metabolic disorder to treat the metabolic disorder, wherein the ultrasound dose regimen comprises a plurality of ultrasound energy doses applied at separate time points.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0009] FIG. l is a schematic representation of a neuromodulation system using a pulse generator according to embodiments of the disclosure;

[0010] FIG. 2 is a block diagram of a neuromodulation system according to embodiments of the disclosure;

[0011] FIG. 3 is a schematic representation of an ultrasound energy application device in operation according to embodiments of the disclosure;

[0012] FIG. 4A is an ultrasound visualization of the spleen that may be used as spatial information to focus on a region of interest in a spleen according to embodiments of the disclosure;

[0013] FIG. 4B is an ultrasound visualization of the liver that may be used as spatial information to focus on a region of interest in a liver according to embodiments of the disclosure;

[0014] FIG. 5 is a flow diagram of a neuromodulation technique according to embodiments of the disclosure;

[0015] FIG. 6 is a schematic illustration of the energy application device configured as an extracorporeal device and including an ultrasound transducer;

[0016] FIG. 7 is a schematic illustration of the energy application device and the pulse generator configured to apply high-intensity focused ultrasound;

[0017] FIG. 8 is an example of an energy application device that may be used in conjunction with the system of FIG. 7;

[0018] FIG. 9 is a schematic illustration of the experimental setup for ultrasound energy application to achieve target physiological outcomes;

[0019] FIG. 10 is an experimental timeline of ultrasound energy application;

[0020] FIG. 11 shows pulse characteristics of the applied ultrasound energy pulses;

[0021] FIG. 12 shows a hydrophone measurement setup;

[0022] FIG. 13 shows an example of an ultrasound pressure field in x-y plane;

[0023] FIG. 14 shows experimental workflow for LPS injection for generating a model of inflammation and/or hyperglycemia/hyperinsulemia and ultrasound treatments;

[0024] FIG. 15A is a schematic illustration of broad vagus nerve stimulation;

[0025] FIG. 15B is a schematic illustration of targeted organ-based peripheral neuromodul ati on;

[0026] FIG. 16A is an experimental timeline of ultrasound energy application to a rat spleen;

[0027] FIG. 16B shows splenic norepinephrine, acetylcholine, and TNF-a at different applied ultrasound energy levels to the rat spleen, shown as ultrasound pressure MPa;

[0028] FIG. 16C shows circulating concentrations of TNF-a for the same conditions as FIG. 16B

[0029] FIG. 16D shows splenic IL-la concentrations for the same conditions as FIG. 16B;

[0030] FIG. 16E shows response time for induced changes in splenic TNFa concentrations relative to control;

[0031] FIG. 16F shows a 2D ultrasound image of the rat spleen used to focus the ultrasound stimulus to spatially select the splenic target;

[0032] FIG. 16G shows the timeline of a study designed to measure the duration of effect of the stimulus on cholinergic anti-inflammatory pathway activation;

[0033] FIG. 16H shows the concentration of splenic TNF-a after protective ultrasound treatments;

[0034] FIG. 161 shows the concentrations of activated/phosphorylated kinases as a result of splenic ultrasound modulation;

[0035] FIG. 16J shows example ultrasound burst durations and the effects on norepinephrine (NE), acetylcholine (ACh), and tissue necrosis factor alpha (TNF-a) concentrations in ultrasound-stimulated spleens (after LPS injection) using alternative ultrasound- stimul ati on parameters ;

[0036] FIG. 16K shows example ultrasound carrier frequencies and the effects on norepinephrine (NE), acetylcholine (ACh), and tissue necrosis factor alpha (TNF-a) concentrations in ultrasound-stimulated spleens (after LPS injection) using alternative ultrasound- stimul ati on parameters ;

[0037] FIG. 17A shows the effect of splenic ultrasound modulation compared to standard electrode or implant-based vagal nerve stimulation (VNS) on splenic TNF-a and in the presence of various inhibitors;

[0038] FIG. 17B shows the effect of a-bungarotoxin on splenic concentrations of (left) norepinephrine (NE) and (right) TNF-a after ultrasound stimulation of LPS-treated rodents with and without the effects of BTX or a surgical vagotomy;

[0039] FIG. 17C shows data comparing the effect of VNS (at several stimulation intensities and frequencies) versus splenic ultrasound stimulation (at 0.83 MPa) on heart rate;

[0040] FIG. 17D shows data confirming the previously observed side effect of VNS on attenuation of LPS-induced hyperglycemia and absence of this side-effect when using splenic ultrasound stimulation;

[0041] FIG. 18A is a 2D ultrasound image of the rat liver used to focus the ultrasound stimulus;

[0042] FIG. 18B shows the effect of ultrasound stimulation of the liver on LPS-induced hyperglycemia;

[0043] FIG. 18C shows measurements of relative concentrations (compared to no ultrasound stimulation) of several molecules associated with either insulin sensitivity and both insulin mediated as well as non-insulin dependent glucose uptake in the liver and changes in hypothalamic markers associated with metabolic function;

[0044] FIG. 18D shows cFOS immunohistochemistry images (left) and data showing the number of activated neurons in the LPS control and ultrasound stimulated samples (right);

[0045] FIG. 18E shows additional immunohistochemistry images showing cFOS expression in the brainstem in LPS control (top) versus ultrasound stimulated samples (bottom);

[0046] FIG. 18F shows example MRI overlays between activation maps (over SPGR volume; left) and a brain atlas (over SPBR volume; right);

[0047] FIG. 18G shows a graph of ADC increase in both left and right paraventricular nuclei of the hypothalamus (PVNs);

[0048] FIG. 19 shows circulating glucose after liver stimulation in a diabetic rat;

[0049] FIG. 20 shows circulating triglycerides after liver stimulation in a diabetic rat;

[0050] FIG. 21 shows circulating glucagon after liver stimulation in a diabetic rat;

[0051] FIG. 22 shows circulating insulin after liver stimulation in a diabetic rat;

[0052] FIG. 23 shows circulating leptin after liver stimulation in a diabetic rat;

[0053] FIG. 24 shows circulating norepinephrine after liver stimulation in a diabetic rat; [0054] FIG. 25 shows hypothalamic insulin receptor substrate 1 (IRS-l) after liver stimulation in a diabetic rat;

[0055] FIG. 26 shows hypothalamic phospho-Akt after liver stimulation in a diabetic rat;

[0056] FIG. 27 shows hypothalamic GLUT4 after liver stimulation in a diabetic rat;

[0057] FIG. 28 shows hypothalamic norepinephrine after liver stimulation in a diabetic rat;

[0058] FIG. 29 shows hypothalamic glucose-6-phosphate after liver stimulation in a diabetic rat;

[0059] FIG. 30 shows hypothalamic glucagon-like peptide (GLP-l) after liver stimulation in a diabetic rat;

[0060] FIG. 31 shows hypothalamic gamma-aminobutyric acid (GABA) after liver stimulation in a diabetic rat;

[0061] FIG. 32 shows hypothalamic brain-derived neurotrophic factor (BDNF) after liver stimulation in a diabetic rat;

[0062] FIG. 33 shows hypothalamic neuropeptide Y (NPY) after liver stimulation in a diabetic rat;

[0063] FIG. 34 shows hepatic IRS-l after liver stimulation in a diabetic rat;

[0064] FIG. 35 shows hepatic phospho-Akt after liver stimulation in a diabetic rat;

[0065] FIG. 36 shows hepatic glucose transporter 2 (GLUT2) after liver stimulation in a diabetic rat;

[0066] FIG. 37 shows hepatic norepinephrine after liver stimulation in a diabetic rat; [0067] FIG. 38 shows hepatic glucose-6-phosphate after liver stimulation in a diabetic rat;

[0068] FIG. 39 shows hepatic GLP-l after liver stimulation in a diabetic rat;

[0069] FIG. 40 shows pancreatic glucagon after liver stimulation in a diabetic rat;

[0070] FIG. 41 shows pancreatic insulin after liver stimulation in a diabetic rat;

[0071] FIG. 42 shows pancreatic leptin after liver stimulation in a diabetic rat;

[0072] FIG. 43 shows pancreatic IRS-l after liver stimulation in a diabetic rat;

[0073] FIG. 44 shows pancreatic GLUT2 after liver stimulation in a diabetic rat;

[0074] FIG. 45 shows pancreatic phospho-Akt after liver stimulation in a diabetic rat; and

[0075] FIG. 46 shows persistent effects post-treatment in a Zucker rat model.

DETAILED DESCRIPTION

[0076] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers’ specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0077] Any examples or illustrations given herein are not to be regarded in any way as restrictions on, limits to, or express definitions of, any term or terms with which they are utilized. Instead, these examples or illustrations are to be regarded as being described with respect to various particular embodiments and as illustrative only. Those of ordinary skill in the art will appreciate that any term or terms with which these examples or illustrations are utilized will encompass other embodiments that may or may not be given therewith or elsewhere in the specification and all such embodiments are intended to be included within the scope of that term or terms. Language designating such non-limiting examples and illustrations includes, but is not limited to:“for example,”“for instance,”“such as,”“e.g.,” “including,” and“in one (an) embodiment.”

[0078] Provided herein are techniques for neuromodulation based on direct and focused stimulation of targeted regions of interest. The targeted regions of interest may be any tissue or structure in the body having a plurality of types of axon terminals forming synapses with non-neuronal cells or fluids. In one example, the region of interest may be in an organ or structure, such as a liver, pancreas, or gastrointestinal tissue. Neuromodulation of regions of interest permits a limited and nonablative application of energy to only the targeted regions of interest and without the energy being applied outside of the regions of interest. Energy application may trigger effects outside of the regions of interest, e.g., in the organ containing the region of interest as well as in other organs and structures that do not contain the region of interest. However, these effects outside of the region/s of interest may be achieved without direct energy application to areas outside of the region/s of interest. Accordingly, systemic effects may be realized through local energy application. As provided herein, the systemic effects may also be realized with intermittent and noncontinuous energy application. Further, the effects may be realized for hours and days after the energy application.

[0079] In certain embodiments, the neuromodulation as provided herein may be used as a treatment for chronic disorders to alter progression and, in certain embodiments, to reverse the effects of chronic disorders. In one embodiment, a patient diagnosed with a disease may present for neuromodulation treatment. After treatment, the patient may have achieved clinical benchmarks that are associated with a healthy patient. For example, a patient with diabetes may present with blood glucose and/or insulin levels outside of a normal range. Post treatment, the patient may have blood glucose and/or insulin levels that are in the normal range. In another example, a patient with abnormal immune responsiveness may, post treatment, regain characteristics of normal immune response, including altered immune cell populations and/or altered lymph drainage.

[0080] The neuromodulation to targeted regions of interest may yield treatment results that persist beyond the treatment time. The neuromodulation may alter a disease state of a patient to achieve long-lasting results. For example, a treatment of repeated energy applications to targeted regions of interest over a defined period of time may yield persistent improvements in disease symptoms. In one embodiment, the improvements are relative to untreated patients or patients treated with conventional therapies. The predefined period of time may be a time window of hours or days within which the treatment occurs. Further, the treatment may include one or more separate energy application events within the predefined period of time.

[0081] Also provided herein are techniques that may be applied to the treatment of glucose metabolism and associated disorders and that may alter disease progression. In one embodiment, liver modulation at one or more regions of interest may be used to treat diabetes (i.e., type 1 or type 2 diabetes), hyperglycemia, sepsis, trauma, infection, diabetes-associated dementia, obesity, or other eating or metabolic disorders. In one example, neuromodulation may be used to promote weight loss, control appetite, treat cachexia, or increase appetite. For example, direct pancreatic stimulation may result in increased appetite, while direct liver stimulation may cause a decrease in NPY, which in turn promotes signals of satiety. The neuromodulation as provided herein may alter a glucoregulatory setpoint relative to a pretreatment state to achieve long-lasting treatment effects days, weeks, and/or months beyond treatment. In one example, neuromodulation in a diabetic patient may yield an initial reduction in circulating glucose relative to the baseline (before neuromodulation) during the treatment window (e.g., hours or days). However, after treatment has concluded, while the circulating glucose may increase in the time after treatment, the increase may plateau at a new setpoint that is significantly lower than the pre-treatment setpoint. The new setpoint may be at a level associated with clinical benefits.

[0082] As provided herein, the neuromodulation treatment as provided herein may involve repeated and separate energy application to the same region of interest over the predefined treatment time. For example, the neuromodulation may be once daily at the region of interest (e.g., the porta hepatis), whereby the once daily treatment may be according to preset modulation parameters, for two or more consecutive days.

[0083] The present techniques relate to modulation of synapses at axon terminals in a tissue via an application of energy by an energy source. For example, these may include axoextracellular synapses formed between presynaptic axon terminals and postsynaptic non-neuronal cells. In addition, while certain disclosed embodiments are discussed in the context of axoextracellular synapses, it should be understood that the axon terminals may form axosecretory, axosynaptic, axosomatic or axoextracellular synapses, and that additionally or alternatively, these synaptic types are contemplated as being selectively modulated, as provided herein. Further, certain axon terminals may terminate in interstitial or body fluid that may also experience neurotransmitter release as a result of the modulation. The disclosed synapses may be modulated to alter an activity in the synapses, e.g., a release of neurotransmitters from the presynaptic axon terminals. In turn, the altered activity may lead to local effects and/or non-local (e.g., systemic) effects. The present techniques permit energy to be focused in a targeted manner on a volume of tissue that includes certain axon terminals to preferentially directly activate the targeted axon terminals to achieve desired outcomes. In this manner, the targeted axon terminals within a region of interest are activated while, in certain embodiments, axon terminals in the same organ or tissue structure but that are outside of the region of interest are not activated. Because organs and tissue structures may include different types of axon terminals that

form synapses with different types of postsynaptic non-neuronal cells, the region of interest may be selected that includes axon terminals that, when activated, yield the desired targeted physiological outcome. Accordingly, the modulation may target a specific type of axon terminal on the basis of the presynaptic neuron type, the postsynaptic cell type, or both.

[0084] For example, in one embodiment, the type of axon terminal may be an axon terminal forming an axoextracellular synapse with a resident (i.e., tissue-resident or non circulating) liver, pancreatic, or gastrointestinal tissue cell. That is, the axoextracellular synapse is formed at a junction between an axon terminal and a nonneuronal cell or interstitial or body fluid. Accordingly, the application of energy leads to modulation of metabolic function in the region of interest. However, it should be understood that, based on the population of axon terminal types and the characteristics of the presynaptic neuron type and postsynaptic cells (e.g., immune cells, lymph cells, mucosal cells, muscle cells, etc.) of the axoextracellular synapse, different targeted physiological effects may be achieved. Accordingly, applying energy to a region of interest in a tissue of a subject may activate axon terminals and their associated axoextracellular synapse within the region of interest while untargeted axon terminals (and associated synapses) outside of the region of interest may be unaffected. However, because modulation may result in systemic effects, untargeted axon terminals outside of the region of interest may experience certain systemic changes as a result of the activation of the axon terminals within the region of interest. As provided herein, preferential activation or direct activation may refer to cells or structures that experience direct application of energy within a region of interest. That is, axon terminals, axoextracellular synapses, and/or postsynaptic non-neuronal cells or interstitial or body fluid that directly experience the applied energy as provided herein.

[0085] The human nervous system is a complex network of nerve cells, or neurons, found centrally in the brain and spinal cord and peripherally in the various nerves of the body. Neurons have a cell body, dendrites and an axon. A nerve is a group of neurons that serve a particular part of the body. Nerves may contain several hundred neurons to several hundred thousand neurons. Nerves often contain both afferent and efferent neurons.

Afferent neurons carry signals to the central nervous system and efferent neurons carry signals to the periphery. A group of neuronal cell bodies in one location is known as a ganglion. Electrical signals generated in the nerves (e.g., via stimulation, which may be intrinsic or externally applied) are conducted via neurons and nerves. Neurons release neurotransmitters at synapses (connections) adjacent to a receiving cell to allow continuation and modulation of the electrical signals. In the periphery, synaptic transmission often occurs at ganglia.

[0086] The electrical signal of a neuron is known as an action potential. Action potentials are initiated when a voltage potential across the cell membrane exceeds a certain threshold. This action potential is then propagated down the length of the neuron. The action potential of a nerve is complex and represents the sum of action potentials of the individual neurons in it. The junction between the axon terminals of a neuron and the receiving cell is called a synapse. Action potentials travel down the axon of the neurons to its axon terminal, the distal termination of the branches of an axon nerve that forms a presynaptic ending or a synaptic terminal of the nerve fiber. The electrical impulse of the action potential triggers migration of vesicles containing neurotransmitters to a presynaptic membrane of the presynaptic axon terminal and ultimately the release of the neurotransmitters into a synaptic cleft (e.g., the space formed between the presynaptic and the postsynaptic cell) or the axoextracellular space. A synapse that reaches a synaptic terminal to convert the electrical signal of the action potential to a chemical signal of neurotransmitter release is a chemical synapse. Chemical synapses may be contrasted with electrical synapses in which the ionic currents flowing into a presynaptic axon terminal can cross the barrier of the two cell membranes and enter a postsynaptic cell.

[0087] The physiological effect of the action potential is mediated by ion movement across a cell membrane. Neurons actively maintain a resting membrane potential via ion pumps that facilitate movement of ions such as Na+, K+, and CT through the neuronal membrane. Different types of neurons may maintain different resting potentials, e.g., -75mV to -55mV. An action potential is generated by an influx of ions, i.e., a movement of charge to generate a large deviation in the membrane potential that is associated with a temporary rise in voltage across the membrane, e.g., a rise to a membrane potential in a range of 30-60 mV. The action potential in an individual neuron may be initiated in response to a neurotransmitter release from a presynaptic (e.g., upstream) neuron, which in turn results in receptor binding at the postsynaptic cell and a cascade of events which leads to an influx of ions and membrane depolarization that results in an action potential that is propagated through the nerve.

[0088] Synapses may be located at a junction between two neurons, which permits an action potential to be propagated down a nerve fiber. However, axon terminals may also form synapses at the junctions between neurons and non-neuronal cells or may terminate at interstitial fluid or body fluid. Examples of synapse types are synapses with immune cells at a neuroimmune junction, synapses with resident sensory cells within an organ, or synapses with gland cells. Release of neurotransmitters into a synaptic cleft and binding to receptors in a postsynaptic membrane of a postsynaptic cell results in downstream effects that are dependent on the nature of the presynaptic neuron and the specific neurotransmitters released as well as the nature of the postsynaptic cell, e.g., types of available receptors of the postsynaptic cell. In addition, an action potential may be excitatory or inhibitory. An excitatory postsynaptic action potential is a postsynaptic potential that makes the postsynaptic neuron more likely to fire or release a subsequent action potential while an inhibitory postsynaptic action potential is a postsynaptic potential that makes the postsynaptic neuron less likely to fire or release a subsequent action potential. Further, several neurons may work together to release neurotransmitters in concert that trigger downstream action potentials or inhibit downstream action potentials.

[0089] Neuromodulation is a technique in which energy from an external energy source is applied to certain areas of the nervous system to activate or increase the nerve or nerve function and/or block or decrease the nerve or nerve function. In certain neuromodulation techniques, one or more electrodes are applied at or near target nerves, and the application of energy is carried through the nerve (e.g., as an action potential) to cause a physiological response in areas of the downstream of the energy application site. However, because the nervous system is complex, it is difficult to predict the scope and eventual endpoint of the physiological response for a given energy application site.

[0090] While strategies for ultrasound modulation of the central nervous system (i.e. brain tissue) have demonstrated successful modulation of neural activity, attempts to modulate peripheral nerves have lagged. For example, ultrasound modulation of the central nervous system (CNS) involves stimulation of cortical regions of the brain, which are rich in synaptic structures while attempts at ultrasound stimulation of peripheral nerves have targeted nerve trunks that are less rich in or devoid of synaptic structures.

[0091] In the present technique, modulation of peripheral nerves involves targeting one or more peripheral axon terminals to in turn impact blood glucose levels and/or to impact glucose regulatory pathways and/or insulin production pathways. In present techniques, repeated energy pulses are applied to the subject’s internal tissue comprising axon terminals that include axoextracellular synapses or neuronal junctions with other cell types, interstitial fluid, or body fluid, e.g., at synapses between a neuronal cell and a non-neuronal cell, whereby applying energy to synapse causes activation of the presynaptic axon terminals and/or activation at the postsynaptic cell to cause a targeted physiological outcome. In one example, stimulation of axon terminals releases neurotransmitter/ neuropeptide or induces altered neurotransmitter release in a vicinity of neighboring non neuronal cells such as secretory or other cells and modulates cell activity. Further, via such modulation, modulation of other tissue structures or organs may be achieved, without direct stimulation. In one embodiment, direct energy application to a relatively small region of an organ (e.g., a volume less than 25% of the total organ volume) may result in stimulation of action potentials in afferent projecting neurons that project into different areas of the brain (e.g., the hypothalamus). However, this result may be achieved without direct brain stimulation of synapse-rich regions. The direct brain stimulation may result in undesired activation of other pathways that may interfere with or swamp a desired physiological outcome. Further, direct brain stimulation may involve invasive procedures. Accordingly,

the present techniques permit granular activation of either brain activity or activity within an organ in a manner that is more targeted and more specific than direct brain stimulation or electrical peripheral nerve stimulation.

[0092] Benefits of the present techniques include local modulation at the region of interest of the tissue to achieve effects that change a concentration of one or more molecules of interest. Further, the local modulation may involve direct activation of a relatively small region of tissue (e.g., less than 25% of a total tissue volume) to achieve these effects. In this manner, the total applied energy is relatively small to achieve a desired physiological outcome. In certain embodiments, the applied energy may be from a non-invasive extracorporeal energy source (e.g., ultrasound energy source, mechanical vibrator). For example, a focused energy probe may apply energy through a subject’s skin and is focused on a region of interest of an internal tissue. Such embodiments achieve the desired physiological outcome without invasive procedures or without side effects that may be associated with other types of procedures or therapy.

[0093] Provided herein are techniques for neuromodulation in which energy from an energy source (e.g., an external or extracorporeal energy source) is applied to axon terminals in a manner such that neurotransmitter release at the site of focus of the energy application, e.g., the axon terminals, is triggered in response to the energy application and not in response to an action potential. That is, the application of energy directly to the axon terminals acts in lieu of an action potential to facilitate neurotransmitter release into a neuronal junction (i.e., synapse) with a non-neuronal cell. The application of energy directly to the axon terminals further induces an altered neurotransmitter release from the axon terminal within the synapse (e.g., axoextracellular synapse) into the vicinity of neighboring non-neuronal cells. In one embodiment, the energy source is an extracorporeal energy source, such as an ultrasound energy source or a mechanical vibrator. In this manner, non-invasive and targeted neuromodulation may be achieved directly at the site of energy focus rather than via modulation at an upstream site that in turn triggers an action potential to activate downstream targets.

[0094] In certain embodiments, the target tissues are internal tissues or organs that are difficult to access using electrical stimulation techniques. Contemplated tissue targets include gastrointestinal (GI) tissue (stomach, intestines), muscle tissue (cardiac, smooth and skeletal), epithelial tissue (epidermal, organ/GI lining), connective tissue, glandular tissues (exocrine/endorcrine), etc. In one example, focused application of energy at a neuromuscular junction facilitates neurotransmitter release at the neuromuscular junction without an upstream action potential. Contemplated modulation targets may include portions of a pancreas responsible for controlling insulin release or portions of the liver responsible for glucose regulation.

[0095] Neuromodulation to the targeted regions of interest may exert a change in physiological processes to interrupt, decrease, or augment one or more physiological pathways in a subject to yield the desired physiological outcome. Further, because the local energy application may result in systemic changes, different physiological pathways may be changed in different ways and at different locations in the body to cause an overall characteristic profile of physiological change in the subject caused by and characteristic of the targeted neuromodulation for a particular subject. While these changes are complex, the present neuromodulation techniques provide one or more measurable targeted physiological outcomes that, for the treated subjects, are the result of the neuromodulation and that may not be achievable without the application of energy to the targeted region/s of interest or other intervention. Further, while other types of intervention (e.g., drug treatment) may yield a subset of the physiological changes caused by neuromodulation, in certain embodiments, the profile of the induced physiological changes as a result of the neuromodulation may be unique to the neuromodulation (and its associated modulation parameters) at the targeted region/s of interest and may differ from patient to patient.

[0096] The neuromodulation techniques discussed herein may be used to cause a physiological outcome of a change in concentration (e.g., increased, decreased) of a molecule of interest and/or a change in characteristics of a molecule of interest. That is, selective modulation of one or more molecules of interest (e.g., a first molecule of interest, a second molecule of interest, and so on) may refer to modulating or influencing a concentration (circulating, tissue) or characteristics (covalent modification) of a molecule as a result of energy application to one or more regions of interest (e.g., a first region of interest, a second region of interest, and so on) in one or more tissues (e.g., a first tissue, a second tissue, and so on). Modulation of a molecule of interest may include changes in characteristics of the molecule such as expression, secretion, translocation of proteins and direct activity changes based on ion channel effects either derived from the energy application itself or as a result of molecules directly effecting ion channels. Modulation of a molecule of interest may also refer to maintaining a desired concentration of the molecule, such that expected changes or fluctuations in concentration do not occur as a result of the neuromodulation. Modulation of a molecule of interest may refer to causing changes in molecule characteristics, such as enzyme-mediated covalent modification (changes in phosphorylation, aceylation, ribosylation, etc). That is, it should be understood that selective modulation of a molecule of interest may refer to molecule concentration and/or molecule characteristics. The molecule of interest may be a biological molecule, such as one or more of carbohydrates (monosaccharaides, polysaccharides), lipids, nucleic acids (DNA, RNA), or proteins. In certain embodiments, the molecule of interest may be a signaling molecule such as a hormone (an amine hormone, a peptide hormone, or a steroid hormone).

[0097] The disclosed neuromodulation techniques may be used in conjunction with a neuromodulation system. FIG. 1 is a schematic representation of a system 10 for neuromodulation to achieve neurotransmitter release and/or activate components (e.g., the presynaptic cell, the postsynaptic cell) of a synapse in response to an application of energy. The depicted system includes a pulse generator 14 coupled to an energy application device 12 (e.g., an ultrasound transducer). The energy application device 12 is configured to receive energy pulses, e.g., via leads or wireless connection, that in use are directed to a region of interest of an internal tissue or an organ of a subject, which in turn results in a targeted physiological outcome. In certain embodiments, the pulse generator 14 and/or the energy application device 12 may be implanted at a biocompatible site (e.g., the abdomen),

and the lead or leads couple the energy application device 12 and the pulse generator 14 internally. For example, the energy application device 12 may be a MEMS transducer, such as a capacitive micromachined ultrasound transducer.

[0098] In certain embodiments, the energy application device 12 and/or the pulse generator 14 may communicate wirelessly, for example with a controller 16 that may in turn provide instructions to the pulse generator 14. In other embodiments, the pulse generator 14 may be an extracorporeal device, e.g., may operate to apply energy transdermally or in a noninvasive manner from a position outside of a subject’s body, and may, in certain embodiments, be integrated within the controller 16. In embodiments in which the pulse generator 14 is extracorporeal, the energy application device 12 may be operated by a caregiver and positioned at a spot on or above a subject’s skin such that the energy pulses are delivered transdermally to a desired internal tissue. Once positioned to apply energy pulses to the desired site, the system 10 may initiate neuromodulation to achieve targeted physiological outcome or clinical effects.

[0099] In certain embodiments, the system 10 may include an assessment device 20 that is coupled to the controller 16 and assesses characteristics that are indicative of whether the targeted physiological outcome of the modulation have been achieved. In one embodiment, the targeted physiological outcome may be local. For example, the modulation may result in local tissue or function changes, such as tissue structure changes, local change of concentration of certain molecules, tissue displacement, increased fluid movement, etc.

[00100] The modulation may result in systemic or non-local changes, and the targeted physiological outcome may be related to a change in concentration of circulating molecules or a change in a characteristic of a tissue that does not include the region of interest to which energy was directly applied. In one example, the displacement may be a proxy measurement for a desired modulation, and displacement measurements below an expected displacement value may result in modification of modulation parameters until an expected displacement value is induced. Accordingly, the assessment device 20 may be configured to assess concentration changes in some embodiments. In some embodiments, the assessment device 20 may be an imaging device configured to assess changes in organ size and/or position. While the depicted elements of the system 10 are shown separately, it should be understood that some or all of the elements may be combined with one another. Further, some or all of the elements may communicate in a wired or wireless manner with one another.

[00101] Based on the assessment, the modulation parameters of the controller 16 may be altered. For example, if a desired modulation is associated with a change in concentration (circulating concentration or tissue concentration of one or more molecules) within a defined time window (e.g., 5 minutes, 30 minutes after a procedure of energy application starts) or relative to a baseline at the start of a procedure, a change of the modulation parameters such as pulse frequency or other parameters may be desired, which in turn may be provided to the controller 16, either by an operator or via an automatic feedback loop, for defining or adjusting the energy application parameters or modulation parameters of the pulse generator 14.

[00102] The system 10 as provided herein may provide energy pulses according to various modulation parameters. For example, the modulation parameters may include various stimulation time patterns, ranging from continuous to intermittent. With intermittent stimulation, energy is delivered for a period of time at a certain frequency during a signal-on time. The signal-on time is followed by a period of time with no energy delivery, referred to as signal-off time. The modulation parameters may also include frequency and duration of a stimulation application. The application frequency may be continuous or delivered at various time periods, for example, within a day or week. The treatment duration may last for various time periods, including, but not limited to, from a few minutes to several hours. In certain embodiments, treatment duration with a specified stimulation pattern may last for one hour, repeated at, e.g., 72 hour intervals. In certain embodiments, treatment may be delivered at a higher frequency, say every three hours, for shorter durations, for example, 30 minutes. The application of energy, in accordance with modulation parameters, such as the treatment duration and frequency, may be adjustably controlled to achieve a desired result.

[00103] FIG. 2 is a block diagram of certain components of the system 10. As provided herein, the system 10 for neuromodulation may include a pulse generator 14 that is adapted to generate a plurality of energy pulses for application to a tissue of a subject. The pulse generator 14 may be separate or may be integrated into an external device, such as a controller 16. The controller 16 includes a processor 30 for controlling the device. Software code or instructions are stored in memory 32 of the controller 16 for execution by the processor 30 to control the various components of the device. The controller 16 and/or the pulse generator 14 may be connected to the energy application device 12 via one or more leads 33 or wirelessly

[00104] The controller 16 also includes a user interface with input/output circuitry 34 and a display 36 that are adapted to allow a clinician to provide selection inputs or modulation parameters to modulation programs. Each modulation program may include one or more sets of modulation parameters including pulse amplitude, pulse width, pulse frequency, etc. The pulse generator 14 modifies its internal parameters in response to the control signals from controller device 16 to vary the stimulation characteristics of energy pulses transmitted through lead 33 to an subject to which the energy application device 12 is applied. Any suitable type of pulse generating circuitry may be employed, including but not limited to, constant current, constant voltage, multiple-independent current or voltage sources, etc. The energy applied is a function of the current amplitude and pulse width duration. The controller 16 permits adjustably controlling the energy by changing the modulation parameters and/or initiating energy application at certain times or cancelling/suppressing energy application at certain times. In one embodiment, the adjustable control of the energy application device is based on information about a concentration of one or more molecules in the subject (e.g., a circulating molecule). If the information is from the assessment device 20, a feedback loop may drive the adjustable control. For example, if a circulating glucose concentration, as measured by the assessment device 20, is above a predetermined threshold or range, the controller 16 may initiate energy application to a region of interest (e.g., liver) and with modulation parameters that are associated with a reduction in circulating glucose. The initiation of energy application may be triggered by the glucose concentration drifting above a predetermined (e.g., desired) threshold or outside a predefined range. In another embodiment, the adjustable control may be in the form of altering modulation parameters when an initial application of energy does not result in an expected change in a targeted physiological outcome (e.g., concentration of a molecule of interest) within a predefined time frame (e.g., 1 hour, 2 hours, 4 hours, 1 day).

[00105] In one embodiment, the memory 32 stores different operating modes that are selectable by the operator. For example, the stored operating modes may include instructions for executing a set of modulation parameters associated with a particular treatment site, such as regions of interest in the liver, pancreas, gastrointestinal tract, spleen. Different sites may have different associated modulation parameters. Rather than having the operator manually input the modes, the controller 16 may be configured to execute the appropriate instruction based on the selection. In another embodiment, the memory 32 stores operating modes for different types of treatment. For example, activation may be associated with a different stimulating pressure or frequency range relative to those associated with depressing or blocking tissue function. In a specific example, when the energy application device is an ultrasound transducer, the time-averaged power (temporal average intensity) and peak positive pressure are in the range of 1 mW/cm2 - 30,000 mW/cm2 (temporal average intensity) and 0.1 MPa to 7 MPa (peak pressure). In one example, the temporal average intensity is less than 35 W/cm2 in the region of interest to avoid levels associated with thermal damage & ablation/cavitation. In another specific example, when the energy application device is a mechanical actuator, the amplitude of vibration is in the range of 0.1 to 10 mm. The selected frequencies may depend on the mode of energy application, e.g., ultrasound or mechanical actuator.

[00106] In another embodiment, the memory 32 stores a calibration or setting mode that permits adjustment or modification of the modulation parameters to achieve a desired result. In one example, the stimulation starts at a lower energy parameter and increases incrementally, either automatically or upon receipt of an operator input. In this manner, the operator may achieve tuning of the induced effects as the modulation parameters are being changed.

[00107] The system may also include an imaging device that facilitates focusing the energy application device 12. In one embodiment, the imaging device may be integrated with or the same device as the energy application device 12 such that different ultrasound parameters (frequency, aperture, or energy) are applied for selecting (e.g., spatially selecting) a region of interest and for focusing energy to the selected region of interest for targeting and subsequently neuromodulation. In another embodiment, the memory 32 stores one or more targeting or focusing modes that is used to spatially select the region of interest within an organ or tissue structure. Spatial selection may include selecting a subregion of an organ to identify a volume of the organ that corresponds to a region of interest. Spatial selection may rely on image data as provided herein. Based on the spatial selection, the energy application device 12 may be focused on the selected volume corresponding to the region of interest. For example, the energy application device 12 may be configured to first operate in the targeting mode to apply a targeting mode energy that is used to capture image data to be used for identifying the region of interest. The targeting mode energy is not at levels and/or applied with modulation parameters suitable for preferential activation. However, once the region of interest is identified, the controller 16 may then operate in a treatment mode according to the modulation parameters associated with preferential activation.

[00108] The controller 16 may also be configured to receive inputs related to the targeted physiological outcomes as an input to the selection of the modulation parameters. For example, when an imaging modality is used to assess a tissue characteristic, the controller 16 may be configured to receive a calculated index or parameter of the characteristic.

Based on whether the index or parameter is above or below a predefined threshold, the modulation parameters may be modified. In one embodiment, the parameter can be a measure of tissue displacement of the affected tissue or a measure of depth of the affected tissue. Other parameters may include assessing a concentration of one or more molecules of interest (e.g., assessing one or more of a change in concentration relative to a threshold or a baseline/control, a rate of change, determining whether concentration is within a desired range). Further, the energy application device 12 (e.g., an ultrasound transducer) may operate under control of the controller 16 to a) acquire image data of a tissue that may be used to spatially select a region of interest within the target tissue b) apply the modulating energy to the region of interest and c) acquire image to determine that the targeted physiological outcome has occurred (e.g., via displacement measurement). In such an embodiment, the imaging device, the assessment device 20 and the energy application device 12 may be the same device.

[00109] In another implementation, a desired modulation parameter set may also be stored by the controller 16. In this manner, subject-specific parameters may be determined. Further, the effectiveness of such parameters may be assessed over time. If a particular set of parameters is less effective over time, the subject may be developing insensitivity to activated pathways. If the system 10 includes an assessment device 20, the assessment device 20 may provide feedback to the controller 16. In certain embodiments, the feedback may be received from a user or an assessment device 20 indicative of a characteristic of the target physiological outcome. The controller 16 may be configured to cause the energy application device to apply the energy according to modulation parameters and to dynamically adjust the modulation parameters based on the feedback. For example, based on the feedback, the processor 16 may automatically alter the modulation parameters (e.g., the frequency, amplitude, or pulse width of an ultrasound beam or mechanical vibration) in real time and responsive to feedback from the assessment device 20.

[00110] In one example, the present techniques may be used to treat a subject with a metabolic disorder. The present techniques may also be used to regulate blood glucose level in subjects with disorders of glucose regulation. Accordingly, the present techniques may be used to promote homeostasis of a molecule of interest or to promote a desired circulating concentration or concentration range of one or more molecules of interest (e.g., glucose, insulin, glucagon, or a combination thereof). In one embodiment, the present techniques may be used to control circulating (i.e., blood) glucose levels. In one embodiment, the following thresholds may be used to maintain blood glucose levels in a dynamic equilibrium in the normal range:

Fasted:

Less than 50mg/dL (2.8mmol/L): Insulin Shock

50-70mg/dL (2.8-3.9mmol/L): low blood sugar/hypoglycemia

70-110 mg/dL (3.9-6. lmmol/L): normal

H0-l25mg/dL (6. l-6.9mmol/L): elevated/impaired (pre-diabetic)

125 (7mmol/L): diabetic

Non-fasted (postprandial approximately 2 hours after meal):

70-l40mg/dL: Normal

l40-l99mg/dL (8-1 lmmol/L): Elevated or“borderline’Vprediabetes

More than 200mg/dL: (1 lmmol/L): Diabetes

For example, the techniques may be used to maintain circulating glucose concentration to be under about 200 mg/dL and/or over about 70 mg/dL. The techniques may be used to maintain glucose in a range between about 4-8 mmol/L or about 70-150 mg/dL. The techniques may be used to maintain a normal blood glucose range for the subject (e.g., a patient), where the normal blood glucose range may be an individualized range based on the patient’s individual factors such as weight, age, clinical history. Accordingly, the application of energy to one or more regions of interest may be adjusted in real time based on the desired end concentration of the molecule of interest and may be adjusted in a feedback loop based on input from an assessment device 20. For example, if the assessment device 20 is a circulating glucose monitor or a blood glucose monitor, the real-time glucose measurements may be used as input to the controller 16.

CLAIMS:

1. A modulation system comprising:

an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and

a controller configured to:

spatially select the region of interest;

focus the energy on the region of interest; and

adjustably control repeated application of the energy via the energy application device to the region of interest to induce repeated preferential activation of a subset of the synapses within a predefined time, the subset being located in the region of interest, to cause a persistent change to one or more molecules of interest after the repeated application of energy.

2. The system of claim 1, wherein the controller comprises:

a processor; and

a memory storing instructions configured to be executed by the processor to spatially select the region of interest, focus the energy on the region of interest and the second region of interest, or control the application of the energy, or a combination thereof.

3. The system of claim 1, wherein the controller is configured to receive, from an assessment device, an input indicative of the first molecule concentration.

4. The system of claim 1, wherein the organ is a liver.

5. A modulation system comprising:

an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and

a controller configured to:

spatially select the region of interest;

focus the energy on the region of interest; and

repeatedly control application of the energy via the energy application device to the region of interest to induce preferential activation of a subset of the synapses within a predefined time, the subset being located in the region of interest, to cause a persistent change to one or more molecules of interest after the repeated application of energy.

6. A system for treating diabetes in a subject, the system comprising:

an ultrasound energy application device configured to apply an ultrasound dose regimen to an internal organ; and

a controller adapted to control the ultrasound energy application device to apply the ultrasound dose regimen, wherein the ultrasound dose regimen comprises a plurality of energy doses applied at separate time points within a time window of the ultrasound dose regimen.

7. A modulation system comprising:

an energy application device configured to apply energy to a region of interest in a subject, the region of interest being a sub-region of an organ comprising synapses between neuronal cells and respective non-neuronal cells; and

a controller configured to:

spatially select the region of interest;

focus the energy on the region of interest; and

repeatedly control application of the energy via the energy application device to the region of interest to apply a low duty-cycle energy dose regimen to the region of interest, wherein the low duty-cycle dose regimen comprises a plurality of electrical stimulations that are separated by an adjustable off period of at least 4 hours, wherein the off period is determined at least in part on feedback received by the controller.

8. A method for treating a subject having a metabolic disorder, comprising:

applying an ultrasound dose regimen to an internal organ of the subject having the metabolic disorder to treat the metabolic disorder, wherein the ultrasound dose regimen comprises a plurality of ultrasound energy doses applied at separate time points.