Small animal functional magnetic resonance head fixator

Abstract

The utility model discloses a functional magnetic resonance head fixator for small animals, which belongs to the technical field of biological experiments and comprises a cylinder and a fixing component. The cylinder is composed of a cylinder upper portion and a cylinder lower portion which are arranged in the horizontal direction and matched with each other. A fixed platform arranged in the horizontal direction is arranged on the cylinder wall of the upper part of the cylinder; the fixing platform is provided with fixing holes. The fixing assembly comprises a fixing rod and a fixing piece. One end of the fixing rod is vertically fixed on the skull surface of the small animal, and the other end of the fixing rod penetrates out of the upper part of the cylinder from inside to outside through the fixing hole; and the cylinder lower part is fixed below the cylinder upper part to form a cylinder arranged along the horizontal direction. According to the skull fixing device, the stability and the reliability of fixing the skull of a waking small animal for a long time can be obviously improved, the skull is fixed at a horizontal position during scanning, the accuracy of coronal plane scanning is improved, and the credibility of subsequent whole-brain data analysis is guaranteed.

Description

Technical Field

[0001] The utility model belongs to the technical field of biological experiments and relates to a functional magnetic resonance (MRI) fixator, in particular to a small animal functional magnetic resonance (MRI) head fixator. Background Art

[0002] With the rapid development of basic neuroscience research, functional magnetic resonance imaging (fMRI) of small animal brains has become one of the most critical techniques for studying changes in brain function in vivo. fMRI is widely used in neuroscience research due to its relatively high temporal and spatial resolution and its ability to noninvasively and repeatedly observe neural activity anywhere in the brain. Existing small animal fMRI instruments only allow fMRI examinations of the subject within a narrow testing tube. Full-brain scans typically take over 20 minutes to complete, and the use of paramagnetic metal fixators to secure the skull is prohibited during the examination. Because experimental animals are unable to consciously cooperate in fMRI experiments, continuous isoflurane inhalation anesthesia combined with intravenous dexmedetomidine anesthesia is typically used to eliminate body movements. A plastic nose bar and homemade toothpick ear bars are then used to maintain the animal's head in a horizontal position for the fMRI experiment. However, the following issues exist: 1. The use of anesthetics can significantly affect changes in brain function, distorting test results; 2. Without anesthetics, the aforementioned devices are insufficient to counteract the animal's struggling response when awake; and 3. The fMRI detection tube is confined to a narrow space, and conventional stereotaxic ear bar mounting brackets are too large to be assembled with antimagnetic materials onto the sides of the animal's head and provide a reliable support point. Clearly, performing awake fMRI on small animals urgently requires reliably securing the animal's head within the confined tube, which is crucial for accurately collecting real-time brain function signals. Utility Model Content

[0003] The utility model provides a small animal functional magnetic resonance head fixator to overcome the defects of the prior art.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A functional magnetic resonance imaging (MRI) head holder for small animals comprises a cylinder and a fixing assembly; the cylinder comprises an upper cylinder portion and a lower cylinder portion that are arranged horizontally and match each other; the cylinder wall of the upper cylinder portion has a fixing platform arranged horizontally; the fixing platform has a fixing hole; the fixing assembly comprises a fixing rod and a fixing piece; one end of the fixing rod is vertically fixed to the surface of the small animal's skull, and the other end passes through the fixing hole from the inside to the outside of the upper cylinder portion, and the fixing piece fixes the fixing rod to the fixing platform; the lower cylinder portion is fixed below the upper cylinder portion, forming a cylinder arranged horizontally.

[0006] To optimize the above technical solutions, specific measures taken also include:

[0007] Furthermore, the fixing rod is a bolt and the fixing piece is two nuts; the head of the bolt is vertically fixed to the surface of the skull of the small animal; the two nuts are threadedly connected to the screw portion of the bolt, one nut is located above the fixing platform, and the other nut is located below the fixing platform; when the two nuts are rotated to clamp the fixing platform, the fixing rod is fixed to the fixing platform.

[0008] Furthermore, a rubber pad is attached to the lower surface of the fixed platform.

[0009] Furthermore, the fixing rod has a needle channel arranged along its length and open at the upper end. The inner diameter of the needle channel matches the vertical positioning needle of the stereotaxic instrument, and the fixing rod can be fixedly sleeved on the vertical positioning needle through the needle channel.

[0010] Furthermore, the upper portion of the cylinder has a downwardly recessed fixing groove, and the bottom surface of the fixing groove serves as the fixing platform.

[0011] Furthermore, the materials of the cylinder and the fixing component are both anti-magnetic materials.

[0012] Furthermore, the outer diameter of the cylinder matches the inner diameter of a detection channel of a functional magnetic resonance imaging machine.

[0013] Furthermore, the cross-sections of the upper part and the lower part of the cylinder are both semicircular.

[0014] Regarding fMRI testing, the existing solution is to use toothpicks as ear bars to maintain a horizontal head position with the nose facing forward after the animal is anesthetized. This solution cannot meet the needs of maintaining the animal's head in a conscious state. The present fixator connects the upper and lower parts of the cylinder to provide a force-bearing outer frame. A fixing platform is provided on the upper part of the cylinder, and the fixing platform has fixing holes. The head of the bolt is fixed to the top of the animal's skull with dental cement. The screw portion of the bolt passes through the fixing hole from bottom to top and is fixed to the fixing platform with a nut. Because the fixing platform is in a horizontal position, the bolt fixation ensures that the animal's skull is firmly connected to the upper part of the cylinder in the vertical direction and does not move. When the lower and upper parts of the cylinder are connected to form a cylindrical structure with tape, the animal and the cylinder as a whole can be inserted into the fMRI detection tube for awake scanning experiments.

[0015] The beneficial effects of the present invention are:

[0016] 1. Achieve stable fixation in narrow tubes: Unlike the previous method of inserting ear rods on the left and right sides, this fixator vertically fixes the bolt screw portion by clamping the platform with a nut within the cylinder formed by the upper and lower parts of the cylinder. The bolt head is fixed to the skull with dental cement. This structure fixes the small animal's skull in the vertical direction within the tube cavity. The outer diameter of the cylinder matches the inner diameter of the detection tube, making the fixator extremely compatible with the detection tube of the fMRI machine.

[0017] Second, the skull can be kept in a horizontal position for testing: Because the fixation procedure for the fixator's bolts can be performed under a stereotaxic apparatus, the skull is in a horizontal position when the bolts are placed. The bolts are inserted and guided by vertical positioning pins to connect with the skull, ensuring that the bolt's screw is in a vertical position when the skull is horizontal. When the bolts are fixed vertically to the fixing platform, the fixing platform is in a horizontal position, which ensures that the skull remains in a horizontal position after fixation.

[0018] 3. It can achieve long-term head fixation when the mouse is awake: because the bolt head is firmly connected to the skull with dental cement in advance, the bolt uses a pair of nuts to vertically clamp the fixing platform and rubber pad when in use. The rubber pad has elasticity when under pressure, ensuring that the bolt screw is securely fixed and the mouse's head will not shake due to the mouse's struggle in the awake state.

[0019] 4. Ensures the reliability of data analysis: Because the animal's head is in a standard horizontal position during scanning, the data read during brain tissue layer scanning can establish a more accurate spatial position relationship with the standard brain map, thus ensuring the accuracy of subsequent data analysis.

[0020] 5. A safe test environment can be guaranteed: Because the above structures are all made of anti-magnetic materials, the use process is safe and reliable and will not cause damage to the experimenters and testing machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the three-dimensional structure of the small animal functional magnetic resonance imaging head holder;

[0022] Figure 2 This is a front cross-sectional view of the small animal functional magnetic resonance imaging head holder;

[0023] The marks in the accompanying drawings are: 11, upper part of the cylinder; 12, lower part of the cylinder; 13, fixing platform; 131, fixing hole; 132, rubber pad; 21, bolt; 211, needle channel; 22, nut. DETAILED DESCRIPTION

[0024] The specific implementation of the present utility model is described below with reference to the accompanying drawings.

[0025] like Figure 1 and 2As shown, the utility model provides a small animal functional magnetic resonance head fixator, which includes a cylinder and a fixing component.

[0026] The cylinder consists of an upper cylinder part 11 and a lower cylinder part 12 which are arranged in a horizontal direction and match each other. The wall of the upper cylinder part 11 has a fixing platform 13 arranged in a horizontal direction. The fixing platform 13 has a fixing hole 131. The fixing assembly includes a fixing rod and a fixing piece. One end of the fixing rod is vertically fixed to the surface of the skull of the small animal through dental cement, and the other end passes through the fixing hole 131 from the inside to the outside of the upper cylinder part 11. The fixing piece fixes the fixing rod to the fixing platform 13. The lower cylinder part 12 is fixed below the upper cylinder part 11, forming a cylinder arranged in a horizontal direction, which serves as a force-bearing outer frame.

[0027] Specifically, the upper part 11 of the cylinder has a downwardly concave fixed groove, and the bottom surface of the fixed groove is a fixed platform 13. Specifically, the fixed groove is composed of a pair of side walls and a fixed platform 13. The side walls are arranged perpendicular to the ground in the front-to-back direction, and the fixed platform 13 is arranged parallel to the ground. The upper edge of the side wall is arc-shaped, and the inner and outer diameters of the arc are the same as those of the upper part 11 of the cylinder. The upper edge of the side wall forms an arc connection with the cross-section of the main part of the upper part 11 of the cylinder (the part except the fixed groove). The lower edge of the side wall is a straight line. When the upper part 11 of the cylinder is laid flat with the arc surface facing downward, the lower edge of the side wall is parallel to the ground. The side wall forms a vertical connection with the front and rear edges of the fixed platform 13 through the lower edge. The other two edges of the fixed platform 13 are parallel to the main part of the upper part 11 of the cylinder. When the upper part 11 of the cylinder is laid flat, the fixed platform 13 is parallel to the ground. Of course, the fixed platform 13 can also be a boss surface that protrudes upward from the upper part 11 of the cylinder, which can also realize the function of fixing the fixed rod.

[0028] The cross-sections of the upper part 11 and the lower part 12 of the cylinder are both semicircular. When in use, the curved surface of the upper part 11 of the cylinder faces downward, while the curved surface of the lower part 12 of the cylinder faces upward. The two structures complement each other and are fixed together to form a complete cylinder by wrapping adhesive tape. The outer diameter of the cylinder matches the inner diameter of the detection channel of the magnetic resonance imaging machine and can be inserted into the detection channel as a whole. In the detection pipeline, the upper part 11 of the cylinder is fixed downwardly to the top of the small animal's skull by bolts 21, and the lower part 12 of the cylinder provides a force support point for the upper part 11 of the cylinder.

[0029] In a specific embodiment, the fixing rod is a bolt 21, and the fixing member is two nuts 22. The head of the bolt 21 is vertically fixed to the surface of the skull of the small animal. The two nuts 22 are threadedly connected to the screw portion of the bolt 21, one nut 22 is located above the fixing platform 13, and the other nut 22 is located below the fixing platform 13. The bolt 21 is vertically fixed to the fixing platform 13 by the two nuts 22: when the two nuts 22 are rotated to clamp the fixing platform 13, the fixing rod is fixed to the fixing platform 13. Specifically, when the bolt 21 is screwed with a nut 22 and passes through the fixing hole 131 from bottom to top, because the outer diameter of the nut 22 is larger than the fixing hole 131, it can be ensured that the nut 22 does not pass through the fixing hole 131, thereby limiting the position of the bolt 21. When another nut 22 is screwed from the fixing hole 131, the bolt 21 can be connected to the upper part 11 of the cylinder as a whole through the two nuts 22.

[0030] In a preferred embodiment, a rubber pad 132 is attached to the lower surface of the fixing platform 13. When the nut 22 is tightened toward the fixing platform 13, the rubber pad 132 is squeezed by the nut 22 below, which ensures that the nut 22 is fixed in position and does not loosen.

[0031] Bolt 21 has an open needle channel 211 along its length. The inner diameter of needle channel 211 matches the vertical positioning needle of the stereotaxic instrument. A fixing rod can be securely positioned over the vertical positioning needle through needle channel 211. During insertion of the stereotaxic instrument, bolt 21 moves up and down with the vertical positioning needle, ensuring that bolt 21 remains vertical while dental cement is applied to the skull of the small animal.

[0032] The cylinder and the fixing components are made of anti-magnetic materials, such as acrylic or ceramic, to prevent damage to the magnetic resonance imaging machine.

[0033] The application method of the small animal functional magnetic resonance head fixator of the utility model is as follows:

[0034] Taking mice undergoing awake fMRI experiments as an example, the procedure for implanting bolt 21 is as follows: Under satisfactory anesthesia, the mouse's head is fixed to a stereotaxic apparatus. After disinfection with iodine, a longitudinal incision is performed on the scalp to fully expose the anterior and posterior fontanelles. Using a vertical positioning needle, the depth of the needle is measured at the anterior and posterior fontanelles and at positions symmetrically located lateral to the midline. The ear bars and nose bridge are adjusted to equalize the anterior and posterior fontanelles and the positions symmetrically located lateral to the midline. At this point, the skull surface is absolutely horizontal. The vertical positioning needle is raised and moved to a position above the midpoint of the anterior and posterior fontanelles on the midline. An appropriate thickness of dental cement is applied to the top of the skull. The vertical positioning needle is inserted through needle channel 211 to connect to the screw portion of bolt 21. As the vertical positioning needle is lowered vertically, the head of bolt 21 is lowered along with the vertical positioning needle until it contacts the dental cement and adheres to the skull surface. Dental cement is then applied layer by layer until the exposed skull surface is completely covered and the head of bolt 21 is submerged. After confirming that the dental cement has solidified, the needle is withdrawn upwards, completing the implantation of bolt 21 in the skull.

[0035] Seven days after surgery, the animals underwent fMRI experiments. Prior to the formal experiment, the animals were placed in the fMRI experimental room and allowed to acclimate to the noise environment of the machine for three days. After induction of sevoflurane anesthesia, a nut 22 was first screwed onto the bolt 21 securing the animal's head. The bolt then passed through the fixing hole 131 and upward from the fixing platform 13. Another nut 22 was then screwed down the shaft of the bolt 21, securing the two nuts 22 firmly to the platform 13 and the rubber pad. The elasticity of the rubber pad prevented the nuts 22 from loosening easily after tightening. After tightening, the tip of the mouse's nose was ensured to be facing forward. At this point, the bolt 21 completely secured the mouse's head to the upper cylindrical portion 11. After aligning the upper and lower cylindrical portions 11 and 12 to form a cylinder, the cylinder was secured with a single layer of transparent tape. The animal, along with the entire cylinder, was then placed into the detection tube of the fMRI machine. Once the animal regained consciousness, an awake fMRI scan was performed.

[0036] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the present invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should also be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0037] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A small animal functional magnetic resonance imaging head holder, characterized by: including a cylinder and a fixing assembly; The cylinder is composed of an upper cylinder part and a lower cylinder part which are arranged in a horizontal direction and match each other; The wall of the upper part of the cylinder has a fixing platform arranged in the horizontal direction; the fixing platform has a fixing hole; The fixing assembly includes a fixing rod and a fixing piece; One end of the fixing rod is fixed vertically to the surface of the skull of the small animal, and the other end passes through the fixing hole from the inside to the outside and out of the upper part of the cylinder. The fixing piece fixes the fixing rod to the fixing platform; The lower part of the cylinder is fixed below the upper part of the cylinder to form a cylinder arranged in a horizontal direction; The fixing rod has a needle channel arranged along its length and open at the upper end. The inner diameter of the needle channel matches the vertical positioning needle of the stereotaxic instrument. The fixing rod can be fixedly sleeved on the vertical positioning needle through the needle channel.

2. The small animal functional magnetic resonance imaging head holder according to claim 1, characterized in that: in, The fixing rod is a bolt, and the fixing piece is two nuts; The head of the bolt is fixed vertically to the surface of the small animal's skull; Two nuts are threadedly connected to the screw portion of the bolt, one nut is located above the fixed platform, and the other nut is located below the fixed platform; when the two nuts are rotated until they clamp the fixed platform, the fixed rod is fixed to the fixed platform.

3. The small animal functional magnetic resonance imaging head holder according to claim 2, characterized in that: in, A rubber pad is attached to the lower surface of the fixed platform.

4. The small animal functional magnetic resonance imaging head holder according to claim 1, characterized in that: in, The upper part of the cylinder is provided with a downwardly recessed fixing groove, and the bottom surface of the fixing groove is the fixing platform.

5. The small animal functional magnetic resonance imaging head holder according to claim 1, characterized in that: in, The cylinder and the fixing component are both made of antimagnetic materials.

6. The small animal functional magnetic resonance imaging head holder according to claim 1, characterized in that: in, The outer diameter of the cylinder matches the inner diameter of a detection channel of a functional magnetic resonance imaging machine.

7. The small animal functional magnetic resonance imaging head holder according to claim 1, characterized in that: in, The cross sections of the upper part and the lower part of the cylinder are both semicircular.

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