Brain stereotactic method and system based on turtle skull zero point

Abstract

The invention relates to the field of neuroscience experiments and biomedical engineering, and discloses a brain stereotactic method and system based on a turtle skull zero point, and the method comprises the following steps: taking a repeatedly recognizable bony mark point of a turtle skull as a zero point; a plane parallel to the reference plane of the brain stereotaxic instrument is established as an XY plane, and an axis parallel to the zero point probe is taken as a Z axis. Further, the invention provides a coordinate conversion method for converting target point coordinates in a three-dimensional image into a coordinate system of a stereotaxic instrument, which comprises the following steps of: positioning a zero point and a reference point in the image, determining a Z-axis direction, constructing an orthogonal coordinate base, and calculating rigid body transformation from an image coordinate system to a stereotaxic coordinate system; therefore, the three-dimensional displacement, the needle inserting depth and the track parameters for the movement of the positioning arm are output. The device can be used in cooperation with an existing brain stereotaxic instrument suitable for turtles, high-repeatability positioning of turtle brain region electrode implantation / injection is achieved, and the consistency and efficiency of cross-individual and cross-batch experiments are improved.

Description

Technical Field

[0001] This invention relates to the fields of neuroscience experiments and biomedical engineering, and in particular to a method and system for stereotactic brain localization based on a zero point on the skull of a turtle. Background Technology

[0002] Stereotactic brain localization is an indispensable core technology in neuroscience research, biomedical engineering, and brain-computer interfaces. It is primarily used to precisely implant electrodes, probes, or injection catheters into specific brain regions or neural nuclei in living animals. In recent years, turtles, as resilient amphibians capable of adapting widely to complex aquatic and terrestrial environments, have demonstrated significant application value and research potential in underwater bio-robotics, neural modulation, and biomimetic navigation experiments. Therefore, accurate brain region localization in turtles is a crucial prerequisite for conducting related research.

[0003] Currently, existing animal stereotaxic systems, coordinate maps, and supporting equipment are mainly designed for mammals such as rodents (e.g., rats, mice, or non-human primates). Mammal skulls typically have distinct and highly conserved suture points (such as the anterior fontanelle (Bregma) and lambda), which researchers can directly use as standard skull zero points and coordinate references for stereotaxic brain positioning. However, the skull anatomy of turtles differs significantly from that of mammals, lacking universally applicable standard anatomical zero points like "Bregma or Lambda." Furthermore, the fixation components of conventional stereotaxic instruments, such as ear rods and incisor clamps, are difficult to directly adapt to the unique beak morphology and middle ear retraction structure of turtles. This means that existing mammalian head fixation methods and positioning reference standards cannot be directly transferred to turtles. The positioning process in turtles often relies on the operator's personal experience, facing problems such as inconsistent zero points and difficulty in repeatedly establishing positioning coordinate systems.

[0004] On the other hand, with the popularization of medical imaging technology, magnetic resonance imaging (MRI) has become increasingly important. I Three-dimensional medical imaging, such as MRI, is widely used to obtain detailed three-dimensional structural information of the brain in live animals to determine the target location of target nuclei. However, in actual electrode implantation or injection surgery, the target coordinates in the image space must be accurately mapped and transferred to the mechanical coordinate system of the intraoperative stereotactic brain system. For turtle experiments, due to the lack of stable and reproducible external bony landmarks as a calibration bridge between the image and physical space, how to accurately map the target coordinates in the image space into the mechanical coordinate system of the stereotactic brain system presents a significant challenge. IThe stable and accurate transformation of target coordinates in image space to the intraoperative stereotactic coordinate system has always been a major bottleneck in this field. Traditional positioning methods struggle to achieve rigid body transformations between the image coordinate system and the physical execution coordinate system, making it difficult to directly convert "image-calibrated target points" into "instrument execution parameters." This results in a high degree of uncertainty in electrode implantation or injection surgery in turtle brain regions, leading to low consistency, accuracy, and efficiency in positioning across individuals and batches.

[0005] In summary, for experiments in turtle neuroscience and biomedical engineering, the existing stereotaxic positioning system cannot meet the high-precision, high-repeatability positioning requirements of turtle brain regions due to the lack of clearly defined and unified skull zero-point constraints, dedicated fixing and leveling devices, and reliable coordinate transformation algorithms from 3D medical images to physical instruments. Therefore, there is an urgent need in this field for a brain stereotaxic positioning method and system based on reproducible identifiable landmarks on the turtle skull that can accurately fuse medical images into the coordinate system of a stereotaxic instrument. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for stereotactic brain localization based on a zero point in the turtle skull, comprising the following steps: Acquire three-dimensional medical imaging data of turtle heads; Determine the image coordinates o of the skull zero point O in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis of the stereotaxic instrument. I Wherein, the zero point O of the skull is located at the midpoint of the posterior edge of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull. According to the image coordinates o I Image coordinates p I and direction vector z I Construct an orthogonal basis for the image coordinate system; Establish a stereo positioning coordinate system: take the plane that passes through the skull zero point O and is parallel to the reference plane of the brain stereo positioning instrument as the XY plane, take the direction that is parallel to the axis of the zero point probe as the Z axis, take the projection direction of the vector from the skull zero point O to the skull reference point P in the XY plane as the Y axis, and determine the X axis according to the right-hand rule. Based on the orthogonal basis of the image coordinate system and the stereo positioning coordinate system ΣS, calculate the rigid body transformation T from the image coordinate system to the stereo positioning coordinate system; The image coordinates of the target brain region are obtained from the three-dimensional medical image data, and the image coordinates of the target brain region are converted into execution coordinates in the stereo positioning coordinate system ΣS through the rigid body transformation T.

[0007] The present invention also provides a stereotactic system for turtle brains, comprising: The calculation module is used to acquire three-dimensional medical image data of the turtle's head; and to determine the image coordinates o of the zero point O of the skull in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis. I According to the image coordinates o I Image coordinates p I and direction vector z I Construct an orthogonal basis for the image coordinate system; establish a stereo positioning coordinate system and calculate the rigid body transformation from the image coordinate system to the stereo positioning coordinate system; convert the image coordinates of the target brain region into the execution coordinates in the stereo positioning coordinate system through the rigid body transformation and output them; The head fixing and leveling component is used to support and fix the turtle's body, as well as adjust the turtle's skull posture; A skull zero-point probe and positioning arm assembly, wherein the skull zero-point probe is mounted on the positioning arm, and the positioning arm is used to set the origin of the three-dimensional positioning coordinate system when the tip of the skull zero-point probe touches the skull zero point O of the turtle, and to perform three-dimensional spatial movement according to the execution coordinates output by the calculation module. Wherein, the zero point O of the skull is located at the midpoint of the posterior edge of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull.

[0008] The beneficial effects of this invention are as follows: The following is the section on the beneficial effects of this patent, which you have prepared for your reference. In patent drafting, the beneficial effects should be closely linked to the technical features employed in the invention, objectively stating the technological advancements and advantages directly resulting from these features: Compared with the prior art, the present invention has the following beneficial effects: This invention addresses the technical challenge of lacking a universally accepted standard anatomical zero point for turtles, similar to that of mammals (Bregma / Lambda). For the first time, this invention proposes using repeatable bony landmarks on the dorsal side of the turtle skull ("8 o'clock" as the skull zero point and "7 o'clock" as the reference point) as the positioning reference, and using the line connecting "7 o'clock and 8 o'clock" combined with the reference plane of a stereotaxic instrument as the directional constraint of the spatial coordinate system. This technique establishes a standardized spatial reference system suitable for turtles, significantly eliminating positioning drift caused by differences in operator experience and subjective judgment of anatomical structures, and achieving a highly repeatable coordinate system establishment.

[0009] This invention proposes a rigid body transformation algorithm for converting the coordinate system of three-dimensional medical images (such as MRI) to the coordinate system of an intraoperative stereotactic brain imaging system. By accurately locating the zero point and reference point in the image data and extracting the Z-axis direction vector to construct an orthogonal basis, the translation and rotation relationships between the two coordinate systems can be calculated. This method can directly and accurately convert the coordinates of any target brain region determined in the image space into the three-axis physical displacement and needle insertion depth of the positioning arm on the stereotactic body, allowing the target point planned in the image to be directly "landed" on the instrument readings. This completely changes the problem of high blindness in traditional turtle brain surgery positioning and greatly improves the targeting accuracy of electrode implantation or injection.

[0010] The supporting system of this invention employs an extended base plate and a tortoise shell limiting baffle, a semi-circular ear rod adapted to the concave middle ear of tortoises, and a special mouth clamp with an insertion hole. This perfectly matches the beak morphology and shell characteristics of tortoises, achieving stable and reliable three-point fixation of the "mouth + both ears," and supporting life support operations such as tracheal intubation while stabilizing the head. Furthermore, by introducing a magnetic skull leveler, the tortoise's head posture can be quickly adjusted without damage, ensuring that the dorsal side of its skull is precisely parallel to the positioning instrument's reference plane. This effectively eliminates mechanical errors introduced by head tilt, further guaranteeing the system-level accuracy and experimental efficiency of stereotactic brain positioning. Attached Figure Description

[0011] Figure 1 : Schematic diagram of turtle skull and its location points; Figure 2 : Three-dimensional coordinates applicable to stereoscopic localization of turtle brains; Figure 3 Schematic diagram of nuclear magnetic resonance coordinate transformation for turtles; Figure 4 : A brain localization device suitable for turtles.

[0012] The attached figures are labeled as follows: 11 is the premaxilla (PMX), 12 is the prefrontal bone (PRFR), 13 is the frontal bone (FR), 14 is the postorbital bone (PORB), 15 is the parietal bone (PAR), and 16 is the squamous bone (SQ). 17 is the skull reference point P, 18 is the skull zero point O; 22 is the XZ plane, 23 is the XY plane; 33 is the X-axis direction, 34 is the Y-axis direction, and 35 is the Z-axis direction. 1-1 is the tortoise shell limiting baffle; 1-2 is the right expansion plate; 2 is the curved platform; 3 is the modified ear rod; 3-1 is the semi-circular ear rod head; 4 is the positioning arm; 5 is the electrode adapter; 6 is the tortoise mouth clamp, of which 6-1 is the length adjustment part and 6-2 is the height adjustment part; 7 is the skull leveler; 8 is the original base plate of the brain positioning instrument. Detailed Implementation

[0013] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” or “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0014] A stereotactic brain localization method based on a zero point in the turtle skull includes the following steps: Acquire three-dimensional medical imaging data of turtle heads; Determine the image coordinates o of the skull zero point O in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis of the stereotaxic instrument. I Wherein, the zero point O of the skull is located at the midpoint of the posterior edge of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull. According to the image coordinates o I Image coordinates p I and direction vector z I Construct an orthogonal basis for the image coordinate system; Establish a stereo positioning coordinate system: take the plane that passes through the skull zero point O and is parallel to the reference plane of the brain stereo positioning instrument as the XY plane, take the direction that is parallel to the axis of the zero point probe as the Z axis, take the projection direction of the vector from the skull zero point O to the skull reference point P in the XY plane as the Y axis, and determine the X axis according to the right-hand rule. Based on the orthogonal basis of the image coordinate system and the stereo positioning coordinate system ΣS, calculate the rigid body transformation T from the image coordinate system to the stereo positioning coordinate system; The image coordinates of the target brain region are obtained from the three-dimensional medical image data, and the image coordinates of the target brain region are converted into execution coordinates in the stereo positioning coordinate system ΣS through the rigid body transformation T.

[0015] The direction vector z, which is parallel to the zero-point probe axis of the stereotaxic instrument, is determined. I The methods include: During the acquisition of three-dimensional medical image data, a radiometric calibration rod coaxial with the zero-point probe is set up, and the centerline of the radiometric calibration rod is extracted from the three-dimensional medical image data as the direction vector z. I .

[0016] Before acquiring the three-dimensional medical image data, the turtle's body was fixed on the stereotaxic instrument and leveled. The normal vector of the leveling reference plane was extracted from the three-dimensional medical image data as the direction vector z. I .

[0017] In the three-dimensional medical image data, the normal vector of a local surface on the dorsal side of the skull is obtained by fitting the normal vector, and the normal vector is then compared with the image coordinates o. I Pointing to the image coordinate p I After orthogonalizing the vector, it becomes the direction vector z. I .

[0018] The step of calculating the rigid body transformation from the image coordinate system to the stereo positioning coordinate system based on the orthogonal basis of the image coordinate system and the stereo positioning coordinate system includes: Rigid body transformation as described in Including rotation matrix With translation vector ,satisfy ,in ,and The coordinates are the origin of the three-dimensional positioning coordinate system.

[0019] After obtaining the execution coordinates in the three-dimensional positioning coordinate system through the rigid body transformation, the following operation steps are also included: The zero-point probe tip on the positioning arm touches the zero point O of the turtle's skull, and the triaxial readings of the positioning arm are cleared to zero. Keeping the Z-axis of the positioning arm from advancing, move the positioning arm in the XY plane to the XY plane coordinate position corresponding to the execution coordinate qS; An opening in the skull is made at the XY plane coordinate position; Keeping the XY plane position unchanged, the positioning arm, which has been replaced by an electrode, is advanced along the Z axis to the Z-axis depth corresponding to the execution coordinate qS.

[0020] Before the zero-point probe tip on the positioning arm reaches the zero point O of the turtle's skull, the process also includes fixing and leveling the turtle's head: The turtle's body is placed on the base plate of the stereoscopic positioning device, and the turtle's shell is locked by the shell limiting baffle. Insert the endotracheal tube through the insertion hole on the mouth clamp and lock the mouth clamp. Use the semi-circular ear rod to press against the middle ear recess of the turtle. Place the magnetic skull leveler under the turtle's head and adjust the skull height and angle so that the dorsal plane of the turtle's skull is parallel to the reference plane of the stereotaxic instrument.

[0021] The present invention also includes a stereotactic system for turtle brains, comprising: The calculation module is used to acquire three-dimensional medical image data of the turtle's head; and to determine the image coordinates o of the zero point O of the skull in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis. I According to the image coordinates o I Image coordinates p I and direction vector z I Construct an orthogonal basis for the image coordinate system; establish a stereo positioning coordinate system and calculate the rigid body transformation from the image coordinate system to the stereo positioning coordinate system; convert the image coordinates of the target brain region into the execution coordinates in the stereo positioning coordinate system through the rigid body transformation and output them; The head fixing and leveling component is used to support and fix the turtle's body, as well as adjust the turtle's skull posture; A skull zero-point probe and positioning arm assembly, wherein the skull zero-point probe is mounted on the positioning arm, and the positioning arm is used to set the origin of the three-dimensional positioning coordinate system when the tip of the skull zero-point probe touches the skull zero point O of the turtle, and to perform three-dimensional spatial movement according to the execution coordinates output by the calculation module. Wherein, the zero point O of the skull is located at the midpoint of the posterior edge of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull.

[0022] The head fixing and leveling assembly includes: a base plate, and a tortoise shell limiting baffle, an ear rod, a mouth clamp and a skull leveler disposed on the base plate; The tortoise shell limiting baffle is used to clamp the tortoise shell placed on the base plate; The mouth clamp has a hole for the tracheal tube to pass through and includes a clamp for clamping and fixing the turtle's mouth. The ear rod is a semi-circular-headed ear rod used to abut against the depression in the middle ear of the turtle; The skull leveler is a magnetic structure, placed below the turtle's head, used to adjust the dorsal plane of the turtle's skull to be parallel to the reference plane of the stereotaxic instrument.

[0023] Example S1 Image Acquisition Preparation: Anesthetize the turtle and monitor its vital signs, and clean the tissue around its head; place an MR imaging calibration rod coaxial with the zero-point probe as needed (or fix the probe substitute in the coaxial direction) for subsequent extraction of the probe direction vector.

[0024] S2 Acquisition of 3D MRI Data: Acquire 3D volumetric MRI data of the glans penis and complete DICOM export or volumetric data reconstruction to obtain the image coordinate system. The three-dimensional voxel / space coordinates below.

[0025] The zero and reference points of the skull in S3 imaging are marked in the MRI volumetric data: Coordinates of skull zero point O (corresponding to skull landmark 18) in the image ; Coordinates of reference point P (corresponding to skull landmark 17) in the image .

[0026] Extracting probe / calibrator orientation from S4 images: Centerline fitting of the calibration rod (or probe substitute) is performed on the MRI volume data to obtain the unit direction vector. The Parallel to the axis of the intraoperative zero-point probe.

[0027] S5 Determining target brain region coordinates in MRI: Select the target brain region (e.g., the center of a nucleus / center of a target structure) in the MRI and record its image coordinates. .

[0028] S6 Calculation of orthogonal basis for constructing image coordinate system: ; ; ; and order The image basis matrix is ​​obtained. .

[0029] S7 Constructing the orthogonal basis of the stereo positioning instrument's coordinate system: In the stereo positioning instrument's coordinate system Define: The plane passing through the zero point O of the skull and parallel to the reference plane of the positioning instrument is the XY plane; The coaxial direction with the zero-point probe is ; Will The projection direction in the XY plane is defined as ; make The instrument basis matrix is ​​obtained. .

[0030] S8 calculates the coordinate transformation from image to stereo positioning device: calculates the rotation matrix. During the procedure, the time was reset to zero at 8 o'clock. The translation vector is obtained. This results in rigid body transformation. .

[0031] S9 calculates the execution coordinates of the target point under the stereo positioning system: converts the target point coordinates to: Output As the three-axis movement and advance depth of the positioning arm of the positioning instrument.

[0032] The S10 positioning device is used to fix the turtle's body and complete three-point fixation: Place the turtle on the positioning device's extended base plate, center and lock it using the turtle shell limiting baffle; pass the tracheal tube through the pre-drilled hole in the mouth clamp and lock the clamp head, while adjusting the mouth clamp length and height to ensure the head posture is appropriate; use a semi-circular ear stick to gently press the middle ear recess to form a "mouth + both ears" three-point fixation. S11 Skull Leveling and Locking of Reference Plane: Place the magnetic skull leveler under the head, adjust the skull posture to the required reference (XY plane parallel to the reference plane of the positioning instrument) using the four corner nuts, and lock it in place by tightening the locking nut. S12 Expose the skull and identify points 17 and 18: Cut and separate the soft tissues of the head to expose the dorsal skull; identify landmarks 17 and 18 based on the skull morphology.

[0033] S13 Zero-point zeroing and coordinate system establishment: Install the zero-point probe on the positioning arm, ensuring the probe tip precisely reaches skull landmark point 18; zero the three-axis readings of the positioning arm, ensuring point 18 corresponds to the origin of the stereo positioning instrument. .

[0034] S14 Positioning arm moves to the target projection position: Keeping the Z-axis stationary, first move the positioning arm in the XY plane to... Position the electrode / drill above the target projection point.

[0035] S15 Skull opening and meningeal treatment: In The skull is drilled at the corresponding location, and dural fenestration / puncture is performed as needed, with the hole diameter matching the electrode diameter.

[0036] S16 Electrode Clamping and Z-axis Advancement Implantation: Secure the electrode to the electrode adapter and connect it coaxially with the positioning arm; while maintaining... Proceed along the Z-axis to [the destination] while keeping the current unchanged. At the corresponding depth, the electrode tip is delivered to the target location to complete electrode implantation.

[0037] S17 Electrode Fixation and Incision Treatment: The electrode is fixed to the skull using bone wax / dental cement / light-cured resin, etc., to complete the closure or leave the interface.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for stereotactic brain localization based on a zero point in the skull of turtles, characterized in that, Includes the following steps: Acquire three-dimensional medical imaging data of turtle heads; Determine the image coordinates o of the skull zero point O in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis of the stereotaxic instrument. I Wherein, the zero point O of the skull is located at the midpoint of the posterior margin of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull. According to the image coordinates o I , image coordinates p I , and direction vector z I , an orthogonal basis of the image coordinate system is constructed; Establish a stereo positioning coordinate system: take the plane that passes through the skull zero point O and is parallel to the reference plane of the brain stereo positioning instrument as the XY plane, take the direction that is parallel to the axis of the zero point probe as the Z axis, take the projection direction of the vector from the skull zero point O to the skull reference point P in the XY plane as the Y axis, and determine the X axis according to the right-hand rule. Based on the orthogonal basis of the image coordinate system and the stereo positioning coordinate system ΣS, calculate the rigid body transformation T from the image coordinate system to the stereo positioning coordinate system; The image coordinates of the target brain region are obtained from the three-dimensional medical image data, and the image coordinates of the target brain region are converted into execution coordinates in the stereo positioning coordinate system ΣS through the rigid body transformation T.

2. The brain stereotactic localization method based on the zero point of the turtle skull according to claim 1, characterized in that, The determining a direction vector z parallel to the zero probe axis of the brain stereotaxic apparatus I includes: In the acquisition of three-dimensional medical image data, a visible calibration rod coaxial with the zero probe is provided, and a center line of the visible calibration rod is extracted as the direction vector z in the three-dimensional medical image data I .

3. The brain stereotactic localization method based on the zero point of the turtle skull according to claim 1, characterized in that, The determining a direction vector z parallel to the zero probe axis of the brain stereotaxic apparatus I includes: Before three-dimensional medical image data acquisition, the tortoise body is fixed on a brain stereotactic instrument and leveled, and a normal vector of a leveling reference plane in the three-dimensional medical image data is extracted as the direction vector z I .

4. The brain stereotactic localization method based on the zero point of the turtle skull according to claim 1, characterized in that, The determining a direction vector z parallel to the zero probe axis of the brain stereotaxic apparatus I includes: In the three-dimensional medical image data, a local surface of the back side of the skull is fitted to obtain a normal vector thereof, and the normal vector is orthogonalized with respect to a vector pointing to the image coordinate o I , and the result is used as the direction vector z I . I ​ 5. The brain stereotactic localization method based on the zero point of the turtle skull according to claim 1, characterized in that, The step of calculating the rigid body transformation from the image coordinate system to the stereo positioning coordinate system based on the orthogonal basis of the image coordinate system and the stereo positioning coordinate system includes: The rigid body transformation Including rotation matrix With translation vector ,satisfy ,in ,and The coordinates are the origin of the three-dimensional positioning coordinate system.

6. The brain stereotactic method based on the zero point of the turtle skull according to claim 5, characterized in that, After obtaining the execution coordinates in the three-dimensional positioning coordinate system through the rigid body transformation, the following operation steps are also included: The zero-point probe tip on the positioning arm touches the zero point O of the turtle's skull, and the triaxial readings of the positioning arm are cleared to zero. Keeping the Z-axis of the positioning arm from advancing, move the positioning arm in the XY plane to the XY plane coordinate position corresponding to the execution coordinate qS; An opening in the skull is made at the XY plane coordinate position; Keeping the XY plane position unchanged, the positioning arm, which has been replaced by an electrode, is advanced along the Z axis to the Z-axis depth corresponding to the execution coordinate qS.

7. The brain stereotactic localization method based on the zero point of the turtle skull according to claim 6, characterized in that, Before the zero-point probe tip on the positioning arm reaches the zero point O of the turtle's skull, the process also includes fixing and leveling the turtle's head: The turtle's body is placed on the base plate of the stereoscopic positioning device, and the turtle's shell is locked by the shell limiting baffle. Insert the endotracheal tube through the insertion hole on the mouth clamp and lock the mouth clamp. Use the semi-circular ear rod to press against the middle ear recess of the turtle. Place the magnetic skull leveler under the turtle's head and adjust the skull height and angle so that the dorsal plane of the turtle's skull is parallel to the reference plane of the stereotaxic instrument.

8. A stereotactic system for turtle brains, used to implement the stereotactic brain positioning method based on a zero point of the turtle skull as described in any one of claims 1 to 7, characterized in that, include: The calculation module is used to acquire three-dimensional medical image data of the turtle's head; and to determine the image coordinates o of the zero point O of the skull in the three-dimensional medical image data. I and the image coordinates p of the skull reference point P I And determine the direction vector z parallel to the zero-point probe axis. I According to the image coordinates o I Image coordinates p I and direction vector z I Construct an orthogonal basis for the image coordinate system; establish a stereo positioning coordinate system and calculate the rigid body transformation from the image coordinate system to the stereo positioning coordinate system; convert the image coordinates of the target brain region into the execution coordinates in the stereo positioning coordinate system through the rigid body transformation and output them; The head fixing and leveling component is used to support and fix the turtle's body, as well as adjust the turtle's skull posture; A skull zero-point probe and positioning arm assembly, wherein the skull zero-point probe is mounted on the positioning arm, and the positioning arm is used to set the origin of the three-dimensional positioning coordinate system when the tip of the skull zero-point probe touches the skull zero point O of the turtle, and to perform three-dimensional spatial movement according to the execution coordinates output by the calculation module. Wherein, the zero point O of the skull is located at the midpoint of the posterior edge of the parietal bone on the dorsal midline of the skull, and the reference point P of the skull is located at the midpoint of the suture between the frontal and parietal bones on the dorsal midline of the skull.

9. The turtle brain stereotaxic positioning system according to claim 8, characterized in that, The head fixing and leveling assembly includes: a base plate, and a tortoise shell limiting baffle, an ear rod, a mouth clamp and a skull leveler disposed on the base plate; The tortoise shell limiting baffle is used to clamp the tortoise shell placed on the base plate; The mouth clamp has a hole for the tracheal tube to pass through and includes a clamp for clamping and fixing the turtle's mouth. The ear rod is a semi-circular-headed ear rod used to abut against the depression in the middle ear of the turtle; The skull leveler is a magnetic structure, placed below the turtle's head, used to adjust the dorsal plane of the turtle's skull to be parallel to the reference plane of the stereotaxic instrument.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the data processing and coordinate transformation steps in the brain stereotactic localization method based on the zero point of the turtle skull as described in any one of claims 1 to 5.

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