PERFUSION CHAMBER, SYSTEM AND METHOD FOR STUDYING THE BRAIN ACTIVITY IN VIVO Russian patent published in 2021 - IPC A61B5/25 A61B17/80 A61B90/10 A61B90/14 B01L99/00 

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine, namely to a perfusion chamber, a system and a method for studying the brain activity in vivo. The perfusion chamber for studying the brain activity in vivo constitutes a monolithic structure. The structure is made of plastic exhibiting dielectric properties, applying a technology based on a three-dimensional digital model. The structure consists of a load-bearing body. The body comprises an input channel for the perfusion solution, a channel for introducing the reference electrode, a channel for introducing the input perfusion solution temperature sensor, a preliminary chamber, an input spiral chute between the preliminary and main chambers, a main chamber, an output spiral chute between the main chamber and the perfusion solution output hole, a perfusion solution output hole, mounting grooves, a point for attaching the skull of an animal. The input channels of the chamber are made in the form of through ducts. The through ducts exit into the preliminary chamber. The preliminary chamber is connected with the main chamber by means of an inlet spiral chute. The exit from the preliminary chamber is located above the bottom of the main chamber and is configured to supply a liquid gravitationally. The main chamber has the shape of a truncated paraboloid of rotation and is connected by an outlet spiral chute with the perfusion solution output hole in the lower part of the perfusion chamber, configured to accommodate a second temperature sensor for controlling the temperature of the output solution. Located along the perimeter of the perfusion chamber are three mounting grooves for attachment to the stereotactic apparatus. The point of attachment of the skull of an animal is located at the bottom of the main chamber and is made in the form of a truncated cone adapted to the size and curvature of the skull of the studied animal. The system for studying the brain activity in vivo consists of a perfusion chamber and a brain surface clamp. The brain surface clamp is made of plastic with application of the technology based on a three-dimensional digital model. The clamp constitutes a plastic disk with a smooth surface, perforated with a set of periodic round holes. The clamp is equipped with a technical rim along the perimeter of the disk, configured to reinforce the structure. The reinforced plastic disk is connected with a fastener by means of two handles. The fastener is inserted into the clamp holder. The brain surface clamp is therein configured to be replaced in case of failure thereof, applying the technology based on a three-dimensional digital model. The clamp holder is installed in a micromanipulator, configured for adjusting the position and degree of pressure on the brain tissues. The brain surface clamp is placed directly on the surface of the brain in the main chamber of the perfusion chamber after attachment thereof to the animal and removal of a section of the skull and the dura mater. In another variant, the system consists of a perfusion chamber, a brain surface clamp, a system for attaching to a stereotactic apparatus, and a flow perfusion system. The system for attaching to a stereotactic apparatus constitutes support columns whereon the perfusion chamber rests at the points of the mounting grooves. Bolts are passed through the mounting grooves of the perfusion chamber and the support columns. The bolts are secured in the stereotactic apparatus. The perfusion chamber is attached to the animal in the provided point of attachment to the skull of the animal. The flow perfusion system constitutes elements of a perfusion system located consecutively. Each subsequent element is therein located below the previous one to ensure gravitational supply of a liquid, including a buffer tank, a connecting tube, a controller dropper, a connecting tube, a heating linear flow element, a perfusion chamber, a flexible connection, a perfusion solution level adjuster, a vacuum suction channel connected to a vacuum suction system. The flexible connection is made of two fittings connected by a flexible tube. The buffer tank is connected with the controller dropper via a connecting tube, configured to control the flow rate of the perfusion solution and ensure galvanic isolation of the perfusion solution in the perfusion chamber and the buffer tank. The controller dropper, in turn, is connected by means of a tube with the heating linear flow element, configured to set the required temperature of the perfusion solution. The outlet of the heating linear flow element is connected with the perfusion solution input channel of the perfusion chamber by means of a tube. The perfusion solution outlet of the perfusion chamber is connected by means of a flexible connection and is coupled with the perfusion solution level adjuster, configured to perform reciprocating vertical movement thereof and thus adjust the level of perfusion solution in the main chamber due to the effect of communicating vessels, configured for excess perfusion solution in the perfusion solution level adjuster to be removed through the vacuum suction channel connected to the vacuum suction system. In implementation of the method, a preliminary preparatory operation for removing the scalp and the cover tissues is performed on the warmed animal under anesthesia. The skull of the animal is attached to the perfusion chamber at the provided attachment point using first cyanoacrylate glue, then dental cement. The perfusion chamber is attached in the stereotactic apparatus using the mounting grooves. Bolts are inserted into the grooves, passing through the support columns, whereon the claimed perfusion chamber rests, in turn. The perfusion chamber is connected to the flow perfusion system. For this purpose, the outlet of the heating linear flow element is connected with the perfusion solution input channel of the perfusion chamber by means of a tube. The perfusion solution outlet of the perfusion chamber is connected by means of a flexible connection to the perfusion solution level adjuster. The adjuster performs reciprocating vertical movement and thus adjusts the level of perfusion solution in the main chamber due to the effect of communicating vessels. Excess perfusion solution in the perfusion solution level adjuster is removed through the vacuum suction channel connected to the vacuum suction system. The temperature sensors are placed through the perfusion solution input channel in the preliminary chamber and the holes for the perfusion solution outlets to monitor the actual temperature of the input and output solution. A section of the skull and the dura mater is removed. The brain surface clamp is placed directly on the brain surface in the main chamber of the perfusion chamber. Electrophysiological studies of the brain activity are conducted using a reference electrode in the form of silver chlorinated wire. The wire is therein placed in the channel for introducing the reference electrode and recording electrodes located in the brain through the holes of the perforated reinforced plastic disk. Optical studies of the brain activity are conducted by means of recording the electromagnetic emission of the visible and infrared ranges reflected from the brain tissues in the areas of holes of the perforated reinforced plastic disk by video surveillance systems.

EFFECT: apparatus and method for studying the brain activity in vivo are provided for conducting electrophysiological and optical studies of the brain activity, such as studies of the effect of medicinal products and biologically active substances on the brain activity in vivo.

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