Patent Application
20100211081
The present invention relates generally to devices and methods for positioning instruments, such as electrodes, mechanical probes and needles, in the body of an animal. More particularly, the invention provides a microdrive and a modular microdrive assembly for precisely positioning the tips of substantially-rigid medical and scientific instruments in animal bodies without passing the substantially rigid instruments through a tubular guide or mounting the instruments on large and unwieldy stereotactic surgical guide systems, which is particularly useful for chronic implantation of the instruments in conscious and freely-moving animals.
In the fields of medical and experimental neurophysiology, implantable signal recording electrodes (often referred to as sensors, electrical probes or simply “probes”) are carefully inserted into the brain tissue of patient and animal subjects via small passageways drilled into the subject's skull. When the probes have been implanted and precisely positioned in an area of the brain targeted for treatment or study, they can detect and record high-quality action potentials of nearby neuronal populations. Detecting, recording and analyzing such action potentials in the brains of humans and certain laboratory animals, such as monkeys, cats, rats and mice, for instance, permit doctors and scientific researchers to develop new and improved treatments for disorders, injuries and ailments affecting the human brain and/or nervous system, as well as improve their knowledge and understanding of brain activity in animals and humans. Implanted electrodes also are sometimes used, for example, to study and/or stimulate certain areas of the brain when the normal sensory pathways between the brain and other portions of the body have been damaged or destroyed due to traumatic injury or neurological disease. The information obtained from these procedures help engineers and technicians build better and more sophisticated neural prostheses for seriously injured human patients. The information also permits doctors and researchers to monitor and predict epileptic seizures or estimate the effects of anticipated brain surgery.
Signal recording instruments, such as neuronal probes, are usually driven into the target area of the brain using devices known as microdrives. Microdrives typically utilize one or more bent or angled carrier tubes, tubular support hoses or guide cannulae to hold, support and/or guide flexible wire electrodes as they are advanced into the brain tissue. For example, U.S. Pat. No. 5,928,143, issued to McNaughton, the disclosure of which is incorporated herein by reference, describes an implantable multi-electrode device in which the recording electrodes are slidably carried in an array of elongated guide cannulae having lower ends, which are parallel with and adjacent to each other, and upper ends that are inclined outwardly from a central vertical axis by an angle of thirty degrees. The outward thirty-degree incline of the guide cannulae provide sufficient spacing between adjacent cannulae so that the electrodes are capable of being independently adjusted.
Similarly, U.S. Pat. No. 5,413,103, issued to Eckhorn, the disclosure of which is also incorporated herein by reference, describes a microprobe and probe apparatus in which a plurality of microprobes are carried by a plurality of stretched elastic support hoses having lower ends that are parallel and adjacent to each other and upper ends that are inclined outwardly to provide sufficient spacing for a plurality of independently adjustable microdrives.
In “Semi-Chronic Motorized Microdrive and Control Algorithm for Autonomously Isolating and Maintaining Optimal Extracellular Action Potentials,” J. Neurophysiol. 93:570-579 (2005), authors Cham, Branchaud, Nenadic, Greger, Anderson and Burdick describe a motorized microdrive, comprising piezoelectric linear actuators capable of autonomously positioning four independent electrodes carried in hollow steel carrier tubes that each must be “pre-bent” by various amounts to accommodate placement in a common guide tube that is off-center to each carrier tube.
Because the known devices for driving instruments into animal bodies, including the devices described above, require mounting the instruments in carrier tubes, support hoses or cannula that are bent, inclined, angled or curved in some manner, they can only be used to drive and position very flexible (high ductility) instruments capable of sustaining large plastic deformations without damage or catastrophic fracture, such as electrodes made from wire. As compared to high ductility instruments, low ductility instruments, such as probes and electrodes made from silicon, carbon fiber, rigid metal, glass or hard plastic, are relatively stiff and brittle under shear stresses, and are, therefore, much more likely to snap, break or crack under the stresses that would be required to mount them in the bent, angled, curved or inclined guiding and support structures associated with many known instrument positioning devices. Accordingly, the known instrument positioning devices are recognized as unsuitable for use with substantially rigid low ductility instruments.
Nevertheless, substantially rigid low ductility instruments may be preferred, or even required, under certain circumstances, because they tend to resist kinking and bending better than high ductility instruments. As compared to flexible instruments, substantially rigid low ductility instruments can also be more effective because they are less susceptible to being deflected away from the targeted area by intervening tissue, protective membranes or other physiological structures or obstacles. Stiffer and stronger low ductility instruments significantly reduce the risk of encountering these problems because they are capable of withstanding higher compression and tension forces than high ductility instruments. Substantially rigid low ductility instruments also may be more easily extracted from the targeted area because they are less susceptible to catching, pulling, stretching or twisting while moving through tissue. Substantially rigid low ductility instruments may also provide better results than high ductility instruments due to some other inherent advantage or property, such as a higher degree of biocompatibility, better performance in a wider range of temperatures, or a higher resistance to corrosion or contamination due to the presence of water, heat, oxidizing agents and other chemicals, etc.
Stereotactic guide apparatuses capable of holding and positioning instruments that are not bent, angled, curved or inclined during mounting and surgical procedures have been introduced and used in the medical and scientific fields. But such apparatuses are typically mounted on and/or used in conjunction with external three-dimensional neurosurgical headframes or pulmonary surgery chestframes. Such headframes and chestframes are typically large and unwieldy devices that are bolted to the animal's body, which have swinging and/or rotating arcuate rails adapted to receive and hold the stereotactic guide apparatus at some precise distance away from the surface of the tissue or organ to be penetrated by the instrument. Consequently, using such stereotactic guide apparatuses to position instruments generally requires immobile and/or unconscious patients or animals, and thus have been found to be largely unsuitable and impractical for chronic implantation on conscious and freely moving subjects.
Conventional instrument positioning devices typically hold and extend the instruments through tubular-shaped guides and support structures, such as canulae, hoses or pipes. The primary purpose of these tubular-shaped guiding and support structures is to define the two-dimensional location above the tissue where the instruments will enter the tissue. However, rigid and substantially rigid instruments often have structures that are not uniform in diameter along their length, which makes it difficult, if not impossible, to place them in or move them in a precise manner through guiding and support tubes that characteristically have substantially uniform diameters along their length.
Accordingly, there is a need in the medical and scientific research fields for devices for driving and precisely positioning the tips of substantially rigid low ductility instruments, such as probes and needles made from silicon, carbon fiber, rigid metals, hard plastic, or other materials that have little or no elastic or plastic deformation ranges, without passing the substantially rigid instrument through a tubular guide and without requiring that the instrument be mounted on a relatively large and immobilizing frame required for a stereotactic guide apparatus. Such devices would be even more practical and convenient if they could also be used to drive and position the tips of flexible instruments (i.e., medium and high ductility instruments), such as wire probes and electrodes made from soft metals, like copper, silver, aluminum or gold.
As will be described in more detail below, aspects and embodiments of the present invention address the above-described needs, as well as other deficiencies and problems associated with known devices, by providing a microdrive and microdrive assembly for positioning a wide range of different types of instruments, whether those instruments are flexible, inflexible or anywhere in between, but which are especially useful for positioning the tips of substantially rigid instruments having a given or fixed geometry. Stated generally, the microdrive comprises a frame, a bottom plate having a bottom void therein, the bottom plate being adapted to be fixedly secured to the frame and surgically attached to the body so that the bottom void is fixedly disposed about a location on the surface of the body where the tip is to be inserted, a drive rod rotatably mounted to the frame, and a carriage with a threaded bore and a platform for fixedly mounting the substantially rigid instrument, the platform being configured to hold the substantially rigid instrument so as to permit the tip to be extended through the bottom void toward the surface of the body without passing the substantially rigid instrument through a tubular guide. The drive rod has a threaded shaft, which passes through the threaded bore on the carriage so that the threads of the threaded shaft are in complementary contact with the threads of the threaded bore. Rotating the drive rod in one direction (e.g., clockwise) produces a force at the complementary contact that urges the platform on the carriage closer to the surface, thereby forcing the instrument held by the carriage to penetrate (or move further into) the body. Rotating the drive rod in the opposite direction (e.g., counterclockwise) produces an opposite force at the complementary contact that urges the platform on the carriage away from the surface, thereby retracting or extracting the instrument from the body.
When the instrument is an electrical device, such as an electrode, a flexible electric cable carries electrical signals between the instrument and an electrical connector mounted to the frame. The electrical connector is typically coupled to an interface cable that is coupled to a remote signal processor or remote signal generator. When the instrument is a fluid-transporting device, such as a needle, a flexible fluid tube carries fluids between the instrument and a fluid connector mounted to the frame, and the fluid connector is fluidly-coupled to a remote fluid reservoir. In another aspect of the present invention, there is provided a modular microdrive assembly for positioning instruments in the body of an animal, comprising a plurality of microdrives, as described above, which are secured to one or more plates (e.g., a top plate and a bottom plate) which serve to stabilize and orient the plurality of microdrives, and optionally, a protective cover that shields and protects the microdrives and associated connections from external forces.
The term “instrument” encompasses any tool, utensil or implement that is typically inserted and positioned in a body by applying forces which cause that tool, utensil or implement to pierce and penetrate the tissue of the body in a precise and controlled manner. Thus, the term “instrument” includes, without limitation, sensor and stimulation devices, such as electrical and mechanical probes, as well as fluid transporting devices, such as needles. The instruments may be made of any material, including, for example, silicon, carbon fiber, glass, metal, plastic or rubber, and may be fixedly mounted to the platform on the carriage using, for example, an epoxy adhesive, acrylic, polyurethane, cyanoacrylate, or any other type of reliable adhesive. The instrument may also be mounted to the platform on the carriage using a clamp, screw or clip.
Unlike conventional instrument positioning devices, the present invention can be used with substantially rigid, relatively unflexible low ductility instruments because it does not require that the instrument be bent, angled, twisted, stretched or otherwise subjected to elastic or plastic deformation for mounting purposes. Embodiments of the present invention also do not require using neurosurgical headframes, breast frames, chest frames, or any other type of large and immobilizing apparatus bolted to the body, which is designed to hold the positioning device away from the surface of the body where the tip of the instrument is to be inserted. Unlike the conventional systems, embodiments and variations of the present invention also achieve precise horizontal and vertical positioning within the animal body without requiring that the instruments be carried in or extended through guiding tubes, hoses or pipes.
Another aspect of the present invention provides a method for positioning the tip of a substantially rigid instrument in the body of an animal using the above-described microdrive, the method comprising the steps of: (1) fixedly mounting the substantially rigid instrument to the platform on the carriage; (2) surgically attaching the bottom plate to the body so that the bottom void is fixedly disposed about a location on the surface of the body where the tip is to be inserted; fixedly securing the frame to the bottom plate so that the tip of the substantially rigid instrument mounted on the platform extends through the bottom void toward the surface of the body without passsing the substantially rigid instrument through a tubular guide; and rotating the drive rod in one direction to produce a force at the complementary contact which urges the platform on the carriage closer to the surface, thereby forcing the tip of the substantially rigid instrument to penetrate the body.
The present invention and various aspects, features and advantages thereof are explained in detail below with reference to exemplary and therefore non-limiting embodiments and with the aid of the drawings, which constitute a part of this specification and include depictions of the exemplary embodiments. In these drawings:
Prior to the present invention, it has not been possible to use substantially rigid, low ductility instruments, such as silicon or carbon fiber probes, glass and metal needles, in certain medical and scientific research applications because the substantially rigid instruments could not be dynamically altered or deformed (i.e., bent, angled or curved) in order to install them on the known instrument driving devices. Microdrives and modular microdrive assemblies according to embodiments of the present invention are capable of positioning both substantially rigid low ductility instruments and substantially flexible high ductility instruments in animal bodies, without altering their given geometries and without using a stereotactic surgery guiding apparatus.
Microdrive
As previously stated, the microdrive comprises a frame, a drive rod rotatably mounted to the frame, and a carriage having a platform configured to hold the instrument in a position adjacent to a location on the surface of the body where the instrument is to be inserted. A bottom plate having a bottom void therethrough is adapted to be fixedly secured to the frame and surgically attached to the body so that the bottom void is fixedly disposed about the location on the surface of the body where the tip is to be inserted. The drive rod has a helical threaded shaft, which passes through a complementary helical threaded bore on the carriage so that both the drive rod and the carriage are removably attached to the frame, and the threads of the threaded shaft are in complementary contact with the threads of the threaded bore. The instrument may or may not be in actual contact with the surface of the body prior to penetration. Turning the drive rod in one direction (whether by manual or automatic means) produces forces at the complementary contact that move the platform on the carriage down the shaft of the drive rod and closer to the surface of the body. This movement causes the tip of the instrument mounted to the platform on the carriage to penetrate the body, or move further into the body. Reversing the rotation of the drive rod produces opposite forces at the complementary contact which cause the platform on the carriage to move up the shaft of the drive rod and away from the surface of the body, thereby retracting or extracting the tip of the instrument.
The instrument may be a mechanical probe, an electrical device, such as an electrical probe, or a fluid transporting instrument, such as a needle. If the instrument is an electrical device, embodiments of the invention provide an electrical connector, which is mounted to the frame, and a flexible electrical cable (or “lead”), which carries electrical signals recorded by the instrument to the electrical connector. The electrical connector is typically coupled to an interface cable, which is configured to carry the electrical signals from the microdrive to a remote signal processor. The electrical connector and flexible electrical cable may also be configured to carry electrical signals in the opposite direction, so that electrical signals produced by a remote signal generator and carried by the interface cable to the electrical connector mounted to the frame may be transmitted to the instrument via the flexible electrical cable (and subsequently introduced into the body of the animal). In some cases, multiple electrical probes, or probes having multiple channels, will be mounted to the microdrive, in which case multiple flexible electrical cables, or flexible cables having multiple transmission channels, may be employed to carry multiple signals from the probe (or probes) to the electrical connector. Where multiple flexible cables are needed to accommodate multiple probes or multiple channels, a flexible ribbon cable, comprising multiple electrical leads, may be used. The interface between the electrical connector on the one hand, and the remote signal processor or generator on the other hand, may comprise an electrical conductor (e.g., a physical wire or cable) or a wireless transmitter/receiver configured to communicate using electromagnetic waves (e.g., radio).
If the instrument mounted to the carriage is a fluid transporting device, such as a needle, then embodiments of the invention may be utilized to precisely position the fluid transporting device in the animal body prior to injecting or collecting fluids. In this case, a fluid connector is coupled to a flexible tube that transports the fluids between the fluid connector and the instrument. The fluid connector is also connected via an interface tube to an external or remote fluid reservoir, pumping mechanism, or both. This arrangement permits fluids extracted from the body with the instrument to pass through the flexible tube, through the fluid connector and the interface tube, and into the remote fluid reservoir. The arrangement may also be used to move fluid in the opposite direction. The fluid connector, the flexible tube or the instrument, or all of them, may contain flow control valves that permit the fluid to travel in only one direction, thereby preventing backward flows and possible contamination of the source.
The carriage on the microdrive of the present invention includes at least one flange (preferably two) that are in slidable contact with the frame, which stabilizes the carriage against compression and tension forces and inhibits the carriage from rotating around the rotational axis of the drive rod. A bracket, coupled to the frame and in slidable contact with the carriage, further stabilizes the carriage, and inhibits the carriage from rotating about an axis substantially transverse to the rotational axis of the drive rod.
In some embodiments, the upper end of the drive rod passes entirely through and out of the top of the frame. In this case, the portion of drive rod extending out of the top of the frame may comprise or be attached to one of a variety of different structures to facilitate rotating the drive rod, such as a turnable knob, a crank, a thumbwheel, a bolt head, a slotted head, a headless slot, a socketed head, a headless socket, a Phillips head, a square-drive head, a Torx head, a Tri-Wing head, a Torq-Set head or a spanner head. However, automatic and/or machine-controlled rotation may be achieved by coupling to the drive rod any suitable motor drive mechanism, including, for example, a direct current (DC) motor, a stepper motor, a servo motor, or a piezoelectric motor. Such motor drive mechanisms, which are already known in the art, may be configured to automatically rotate the drive rod in very precise, predetermined increments, which causes the instrument attached to the carriage to move into or out of the tissue in very precise, predetermined increments. The lower end of the drive rod may be secured to the frame via any fastener or combination of fasteners that will not impede the drive rod's rotation, including, for example, a washer, a nut, a double nut, a c-clip, a pin, or the like.
Modular Microdrive Assembly
A modular microdrive assembly according to an embodiment of the invention comprises one or more microdrives secured to two plates (a top plate and a bottom plate). As previously stated, the bottom plate is adapted for surgical attachment to the region on the animal's body where the instrument is to be inserted. For example, if the instrument is to be inserted into the brain tissue of a laboratory mouse, then the bottom plate may be configured, in terms of its size and shape, for attachment to the mouse's skull immediately adjacent to the targeted brain tissue. The bottom plate has within it a bottom void (comprising, for instance, some type of hole, aperture, bore, slit, passageway, notch, cutout or other opening) that, after attachment to the animal's body, will be adjacent to a location on the surface of the body where the tip of the instrument is to be inserted. The bottom void is sufficiently large to permit the penetrating tip of the instrument to pass through it as the instrument moves toward or away from the targeted area.
The plurality of microdrives on the modular microdrive assembly have a plurality of drive rods. Rotating the plurality of drive rods in one direction (although not necessarily the same direction) produces forces at the complementary contacts that urge the carriages on the plurality of microdrives to move toward the surface of the body, thereby pushing a plurality of instruments mounted to the carriages through the bottom void and the tips of the instruments into the targeted area. When the direction of rotation on the drive rods is reversed, opposite forces are produced at the complementary contacts that urge the carriages away from the surface of the body, thereby pulling the tips of the instruments mounted to the carriages through the bottom void and out of the targeted area. The top plate and bottom plates, which combine to significantly increase the stability of the modular microdrive assembly while it is in use, may be secured to the microdrives using screws, adhesive, or any other suitable means of attachment. However, screws may be preferred because they typically permit the components of the microdrive assembly to be more easily assembled, disassembled and reused.
The plurality of drive rods may be configured to rotate independently. Thus, embodiments of the present invention may used to independently insert and position multiple instruments in the body of an animal (i.e., independent positioning of any subset of the multiplicity of instruments), and maintain the independent positions over an extended period of time. The ability to independently adjust the vertical displacement of a subset of the multiplicity of instruments coupled to the drive rods may be particularly useful, for instance, when the multiplicity of instruments includes instruments of different types (e.g., a mix of electrodes, mechanical probes and needles mounted on a single microdrive assembly concurrently). Alternatively, the plurality of drive rods may be configured to rotate in a synchronized manner in order to facilitate precisely positioning a plurality of instruments simultaneously at substantially the same depth in the animal body and maintaining that same vertical position over an extended period of time.
Exemplary Uses and Applications
It is anticipated that embodiments of the invention may be utilized in a variety of fields, including without limitation the field of experimental neurophysiology. Thus, embodiments of the invention may be surgically implanted on the skulls of laboratory animals, such as rats, mice, birds and monkeys, and used to record neuronal signals originating in the brain while the animal is conscious and mobile. It should be noted, however, that embodiments of the invention may be adapted for surgical implantation on other parts of animal bodies, such as the spinal cord or chest plate, for instance, and then used to precisely position instruments in other biological structures, including, for example, nerve tissue in the spinal cord, blood vessels, air passages, muscles or organs located within the chest cavity, and other parts of the body. Embodiments of the invention may also be used in research experiments or treatment procedures involving anesthetized and/or restrained animals.
Conscious and behaving laboratory animals that have microdrive assemblies implanted on their bodies may tend to tug and pull on the assembly or the interface cable attached to the assembly, which may cause damage to the assembly or disconnect the interface cable or interface connectors. To mitigate this problem, modular microdrive assemblies according to some embodiments of the invention include protective covers that at least partially enclose the interface cable and the microdrives in the microdrive assembly, thereby providing added protection against damage or disconnections resulting from such external forces. The protective cover comprises a substantially rigid receptacle having a hollow interior chamber into which the protected portions of the microdrives and interface cable extend. The interface cable may be clamped or screwed to the protective cover so that pulling and tugging forces introduced to the interface cable are far less likely to disconnect the interface cable from the microdrives. Instead, these forces are transmitted to and dissipated by the entire microdrive assembly, which is itself rigidly affixed to the animal's head or body. Preferably, but not necessarily, the top of the protective cover has holes in it that permit the drive rods to be rotated without disengaging the interface cable or removing the protective cover from the top plate.
Exemplary microdrives and modular microdrive assemblies according to embodiments of the invention will now be described in more detail with reference to the figures.
Receptacle 61 has an inner hollow chamber that is sufficiently large to accommodate a flange 73 on the lower end of interface coupling screw 72, interface wires 78, interface connectors 76 and the portions of the electrical microdrives 28 that extend through and above top plate 50. The inner hollow chamber of receptacle 61 also protects slotted heads 21a fitted to the tops of drive rods 20, the upper portions of the frames 10 and the electrical connectors 22 of the electrical microdrives 28.
As shown in
Typically, modular microdrive assembly 100 is mounted to the skull 96 so that, prior to rotating the drive rods 20, the penetrating tips of the electrical instruments 32b are close to the surface of the exposed dura 98 or the exposed brain tissue 94 where the instruments are to be inserted. The instruments may then be lowered into dura 98 and brain tissue 94 by, for example, inserting a screw driver through holes located in the top of protective cover 60 (best shown in
Although the exemplary modular microdrive assembly 100 shown in
As shown in
Electrical connector 22 is mounted to the upper portion of frame 10 using any reliable adhesive. Flexible electrical cable 24 is electrically coupled at one end to electrical connector 22, and electrically coupled at its other end to the upper portion 32a of electrical instrument 32a-b, which is mounted to platform 14 of carriage 12. Thus, electrical connector 22 serves to secure the upper end of flexible electric cable 24 to the frame 10, which imparts modularity to the device. This modularity permits an operator, for example, to switch from one external interface cable to another without disturbing the flexible electric cable 24 or the instrument 32a-b. For clarity and ease of understanding, the middle portion of the flexible electrical cable 24 has been removed from the diagram shown in
The electrical instrument 32a-b may be made from one or more of a variety of different materials, including, for example, silicon, carbon fiber, glass, metal, plastic or rubber. Platform 14 comprises a surface that is adapted to allow fixedly mounting the instrument to the carriage 12 using, for example, an epoxy adhesive, acrylic, polyurethane, cyanoacrylate, or any other type of reliable adhesive. The electrical instrument 32a-b may also be mounted to the platform 14 on the carriage using a clamp, screw or clip (not shown).
Substantially rigid instruments include instruments having sufficient internal strength and rigidity (stiffness) so that imposing vertical motion (i.e., motion parallel to the Y-axis in
Assembling the various components in the manner described above and as shown by the exploded diagram of
It should also be apparent from
Depending on a number factors, including, for example, the diameter of instrument being inserted, the density and resistance of the penetrated tissue, and obstacles that may be located in the path of the instrument, the inventors of the present invention have observed that operating electrical microdrive 28 to push or pull the tip of electrical instrument 32a-b further into or out of the subject tissue can produce relatively significant insertion and extraction forces at 32b that attempt to tilt or rotate the carriage 12 about tilt axes that are substantially transverse to the intended rotation of drive rod 20 (i.e., around the X- and Z-axes shown in
Fluid microdrive 29 operates substantially in the same manner as electrical microdrive 28. When slotted head 21a is rotated in the counterclockwise direction, for example, the complementary contact 30 between the outside threads of threaded shaft 21b and the inner threads of threaded bore 16 on carriage 12 urges carriage 12 toward the lower end of the drive rod 20, thereby lowering platform 14, which causes the needle (fluid instrument 33a-b) to move toward or further into any tissue immediately below it. Conversely, when slotted head 21a is rotated in the clockwise direction, the complementary contact 30 between the outside threads of threaded shaft 21b and the inner threads of threaded bore 16 on carriage 12 urges carriage 12 away from the lower end of drive rod 20, thereby raising platform 14, which causes the needle to move away from or out of any tissue immediately below it.
Although not specifically shown in the figures, it should be understood and appreciated that a plurality of fluid microdrives 29 (as shown in
Protective cover 60 also includes on its top and front sides, respectively, an outlet 64 that intersects a slit 66, which together are configured to permit passing the wires of an interface cable (discussed in more detail below with reference to
The protective cover 60 may be made from any suitably rigid and/or resilient material, such as plastic, metal or glass, to provide protection for the drive rods, electrical connectors, fluid connectors and interface wires situated within the interior hollow chamber of receptacle 61 against intentional and inadvertent external forces and influences produced, for example, by the subject animal or other animals in the immediate vicinity. Depending on the geometry of the modular microdrive assembly it is intended to cover and protect, protective cover 60 may have any one of a variety of different shapes, including without limitation, a cube, a dome, a pyramid or a cylinder. The protective cover 60 may also be transparent, translucent or opaque.
To secure the interface cable 70 to the protective cover 60, the top portion of interface coupling screw 72 is pushed through outlet 64. The lower portion of interface coupling screw 72 has a circular flange 73 having a sufficient diameter to prevent interface coupling screw 72 from passing entirely through outlet 64 to the outside of protective cover 60. A nut 74 is threaded over the top of interface coupling screw 72, which firmly holds interface coupling screw 72 to the top of the interior hollow chamber of receptacle 61.
Because interface cable 70 is firmly attached to the protective cover 60 by interface coupling screw 72 and nut 74, forces exerted against interface cable 70 (such as tugging and pulling by the subject animal) are transmitted to and dissipated by the rigid and stable dispositions of the top and bottom plates, which are themselves tightly secured to the subject animal's skull with the dental cement. This arrangement creates less strain on the individual interface wires 78, interface electrical connectors 76 and electrical connectors 22 situated inside the protective cover 60. To remove the interface cable 70 from the protective cover 60, nut 74 is removed from interface coupling screw 72 so that interface coupling screw 72 and a sufficient length of interface cable 70 may be drawn into and through the interior hollow chamber of receptacle 61, so that interface cable 70 can pass through the slit 66 and be entirely removed from protective cover 60.
As shown best in
Other microdrive assembly configurations, besides the rectangular-shaped configurations described above, are possible. For example, although the modular microdrive assemblies 100, 102 and 104, described above, are configured so that four microdrives are held in place by rectangular-shaped top and bottom plates, one may also manufacture, for instance, larger or smaller top and bottom plates to accommodate a larger or smaller number of microdrives. Thus, it may be possible, depending on the size and geometry of the implantation site, to put six, eight, ten or more microdrives in a sufficiently-large set of top and bottom plates. In addition, annular-shaped top and bottom plates may be manufactured, which could then provide support for placing a multiplicity of microdrives in a circular configuration. In such configurations, the number of microdrives that could be attached to the top and bottom plates is only limited by the size and thickness of the microdrives, along with the size and geometry of the implantation site. Moreover, it should be appreciated that the frames, as well as the top and bottom plates, do not have to have the same, or even similar, shapes. Thus, a variety of differently-shaped frames, top plates and bottom plates may be combined to produce a single modular microdrive assembly, and to facilitate placing a plurality of microdrives on the single microdrive assembly in a plurality of different orientations to accommodate a variety of different and independent insertion angles for the instruments, as well as simultaneously attaching and independently positioning a mix of different types of instruments.
The size and shape of the top plate may determine the size and shape of the protective cover. For instance, unlike the substantially rectangular-shaped protective cover 60, described above with reference to
In general, using an embodiment of the present invention to record signals produced in the body of an animal comprises the steps of: (1) mounting a recording instrument, such as an electrode, on the carriage of the microdrive; (2) coupling one end of the flexible electrical cable to the instrument; (3) coupling the other end of the flexible cable to the electrical connector mounted on the microdrive; (4) securing the microdrive to the bottom plate; (5) securing the top plate to the microdrive; (6) attaching the bottom plate to the body so that the bottom void in the bottom plate is adjacent to the location of the body where the instrument is to be inserted; (7) electrically coupling one end of an interface cable to the electrical connector mounted to the microdrive; (8) passing at least a portion of the interface cable through the protective cover; (9) connecting the interface cable to a remote signal processor; (10) attaching the protective cover to the top plate; and (11) rotating the drive rod in one direction to produce a force at the complementary contact that urges the carriage closer to the location, thereby pushing the instrument mounted on the carriage through the bottom void and into the body. The steps do not necessarily have to be performed in this order.
Although the exemplary embodiments, uses and advantages of the invention have been disclosed above with a certain degree of particularity, it will be apparent to those skilled in the art upon consideration of this specification and practice of the invention as disclosed herein that alterations and modifications can be made without departing from the spirit or the scope of the invention, which are intended to be limited only by the following claims and equivalents thereof. It can be appreciated, for example, that the concepts and general procedures, as described above with reference to particular embodiments, are valid for positioning instruments in any animal (including humans), and are not limited to use with the aforementioned laboratory animals.
This application is a Continuation-In-Part of International Application No. PCT/US2008/75111, filed on Sep. 3, 2008 (hereby incorporated by this reference), which claims the benefit of U.S. Provisional Application No. 60/970,952, filed on Sep. 8, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60970952 | Sep 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2008/075111 | Sep 2008 | US |
| Child | 12718747 | US |
