FR2811511A1 - Evaluation of modifications to locomotive functions of rodents due to nervous system lesions, uses a horizontal ladder, in a closed corridor, as rodent walks along, infrared sensors detect its movements - Google Patents

Abstract

A first detection system (6) is placed at a distance of several millimeters under a platform (21) and a second (5) above the platform. The system includes infrared beam generators and sensors emitting and detecting beams parallel to bars crossing a corridor walkway. The sensors are positioned between two successive bars. The data from all of the sensors are translated into a single measuring data by means of an OR gate. Rodent locomotion evaluation system includes: (a) a principal corridor (2) having a section suitable for the size of the animal, having a walkway platform (21) formed from a number of crossbars (22) with open space between them; a first detection system (6) designed to detect the paws of the animal between the bars and to provide paw placement error data; a second detection system (5) to determine the position of the animal in the corridor and to provide animal position data; a data processor for the position and error data so as to deduce a locomotion evaluation function for the animal moving along the corridor.

Description

Method and device for evaluating functions

rodent locomotives.

  The present invention relates to a method and device for evaluating the locomotor functions of rodents. It is in particular intended for the study of changes in locomotion, due to central or peripheral nerve damage. It also aims to assess functional recovery after trauma, and the effectiveness of neurotropic or neuromuscular treatments in the context of functional recovery studies after injuries. The invention aims to provide a device and method for automated, simple, rapid measurement, and providing data.

well standardized.

  Different methods of assessing locomotor functions, and more specifically nerve repair techniques, and neuromotor tests, have already been used or at least tried in the laboratory. These methods, which include histological methods, electrophysiological methods and behavioral methods, aim in particular to highlight the toxic effects of a product, the consequences of physical trauma or the therapeutic effects of a substance. For example, after damage to a nerve, such as the sciatic nerve, these methods are used to assess repair in order to make a diagnosis or simply to understand the mechanisms. The present invention is in the field of behavioral methods which are based on the detection and study of behavioral modifications induced by various agents. This demonstration requires prior knowledge of the usual behavior of the animal species used for the test. Attempts have already been made to define and quantify the normal locomotion of the rat on the basis of several characteristic variables of walking. These variables can be defined in terms of positioning of the legs relative to each other, in duration of steps, etc. It has also been proposed to associate locomotor activity with the study of an animal's trajectory under different conditions and to draw results by comparison. Still other methods have attempted to quantify the locomotor capacities by observing movements other than walking, for example by observing and evaluating grooming movements of the rat or grasping by

this one of an object.

  But the description of a behavior present

  the disadvantage of being laborious and, in known methods, requires the sustained attention of a

well-trained experimenter.

  Still other methods aim to analyze the imprints of the paws and to define a certain number of characteristic parameters thereof, and to study the evolution of these parameters over time and / or as a function of trauma or other treatments inflicted on classes d test animals. According to yet another method, video sequences of the movement of the animal are recorded, then, from the images obtained, we study the relative angular positions of the different parts of a member and their evolution during the

displacement.

  If the observation and the analysis can be carried out more easily and more precisely in these last two methods, the fact remains that the choice and the quantification of the parameters retained lead to tedious operations of measurement and calculation which can difficult to undergo extensive automation, since the basic images obtained, footprints or external video image of the member,

  do not lend themselves to reliable automated analysis.

  Furthermore, to avoid being forced to observe spontaneous and therefore unpredictable behavior of the animal, it is also sought to induce the type of behavior to be observed, so

  objective and reproducible, to study it more easily.

  This is why, it is desired to study the most automated techniques possible, allowing reliable, precise and fast measurements. It is one of

  objectives of the present invention.

  The present invention also aims to propose a system making it possible to study the locomotor behavior as a whole and to assess the quality of the locomotor activity, in particular by the most reliable and objective measurement possible of the effects that factors various can cause on the nervous system, in fields such as, for example, in toxicology, pharmacology, neurophysiology, traumatology, etc. With these objectives in view, the invention relates to a device for evaluating the locomotor functions of rodents or the like, characterized in that it comprises: - a main corridor of section adapted to the size of the animal, having a floor formed of a plurality of transverse bars spaced apart and distributed in a longitudinal direction of the corridor, and determining between them transverse openings, - first detection means, adapted to detect an introduction of a leg of the animal between two of the said bars, and provide in response information on the error in placing the legs, - second detection means, to determine the location of the animal in the corridor, and provide location information, - information processing means of location and placement error information, to deduce an assessment of locomotor functions

  of the animal moving in the corridor.

  As will be understood, the evaluation of the locomotor functions is based on a measurement of the faults of placement of the legs on the bars, during a movement of the animal in the corridor, displacement that the animal is forced to carry out when walking on bars. The dimensions in section of the corridor are such that the animal can move along a trajectory corresponding substantially to the longitudinal direction of the corridor, but can also optionally stop there, back off, or even turn around. The detection of said placement faults is carried out by the first detection means, which detect any passage of a leg of the animal between any two bars, therefore reflecting a difficulty in placing its legs on the bars to progress normally. It will be readily understood, and by simplifying the explanation, that, for a given configuration of the bars in the floor and for a substantially identical course, the greater the number of errors, the more this reflects a behavioral deficiency. As will be seen later, the processing of the information obtained with the device will in practice be more elaborate and complex for a better determination of the functions.

locomotives of the animal.

  To detect errors in positioning the legs with correct reliability, the first detection means are arranged so as to pick up the passage of a leg at a height of around a few millimeters to a few centimeters below the floor, for example from 5 to 25 mm, said height possibly being variable along the corridor, adapted and possibly adjustable according to the tests to be carried out and / or

the animal used.

  Preferably, the first detection means include infrared radiation sensor systems, generating infrared beams transverse to the corridor, and therefore substantially parallel to the bars. Also preferably, several, for example three, such sensor systems located between two successive bars will be used to improve the reliability of the detection, the information of all the sensors located between two determined bars being transcribed in a single measurement data by means of an "OR" door or providing a similar logic function. Thus, it suffices that one of the infrared beams is interrupted by a leg of the animal slipped between two bars for a datum

  placement error is generated.

  The second detection means preferably also include infrared sensor systems, emitting beams transverse to the

  corridor and distributed along said corridor, located above

  above the floor. For example, the sensors are placed every 15 cm, about 4 cm above the floor. These beams are interrupted by the passage of the animal, which makes it possible to follow its movement, and to obtain information on the speed of movement, the stops or change of direction, all these data can then be correlated to provide an illustration behavior and its variations over time or depending on the corridor area where the animal is located, as we will see later. The placement error data are also correlated with the location data, to be able to report not only the number of times a leg of the animal falls in the free space between two bars but also

  when and where on the route.

  The corridor is preferably substantially straight, although any other configuration can be envisaged. According to a particular arrangement of the invention, the device comprises a platform for

  departure located at one end of the corridor, and a platform

  finish form located at the opposite end. In order to encourage the animal to move from the departure platform to the arrival platform, the device is preferably equipped with aversive means at the departure platform, and attractive means at the level of the arrival platform. Aversive means, such as intense light, repellant odor, sounds or ultrasound, etc., aim to encourage the animal to leave the arrival platform and therefore to move in the corridor. Equivalently, attractive means such as aperitif odor, sexual pheromone, darkness, etc. also aim to encourage movement to the arrival platform. In the case of a circular corridor, there will not really be a departure or arrival platform, but it will be possible for example to use aversive or attractive removable and / or mobile means to initiate the movement of the animal at the start of the test

  and encourage him to continue moving.

  According to particular provisions of the invention, the bars can have a circular or polygonal section, possibly variable from one bar to another. The bars can also be inclined, or the floor itself as a whole inclined up or down from the starting platform to the arrival platform. The bars can also be distributed irregularly along the corridor, with for example variations in spacing or height. Such variations make it possible to subject the animal to various conditions of movement and to study modifications of its behavior in the face of

various situations.

  The invention also relates to a method for evaluating the locomotor functions of rodents or the like, according to which the animal is made to move in a corridor on a floor formed of bars spaced from one another and oriented transversely to the longitudinal direction of the corridor; its location in the corridor is detected during its movement as well as errors in the placement of its legs on the bars, errors signaled by sensors detecting the passage of a leg in one of the spaces located between any two bars; we measure travel times between predefined positions and we also measure numbers and error times, so as to obtain data representative of the distance traveled and the number and duration of errors, and we deduce an evaluation of the locomotor functions as a function of

  lesions or other neurological deficiencies of the animal.

  According to a preferred arrangement, the data collected is processed by a fuzzy classification algorithm, applying fuzzy logic to classify the animals tested according to the lesions or deficiencies induced in these animals. Other characteristics and advantages will appear

  in the description which will be made of a device and

  a method for assessing the locomotor capacity of

rats, according to the invention.

  Reference will be made to the accompanying drawings in which:) - Figure 1 is a perspective and cutaway view of the device, - Figure 2 is a longitudinal sectional view of the device, - Figures 3 to 8 schematically illustrate different embodiments of the floor of the device, - Figures 9 and 10 illustrate two alternative embodiments of the corridor of the device, - Figure 11 is an example of a graphic representation of the path of the animal in the device during

of a test.

  The device shown in Figures 1 and 2 is in the general form of an elongated box 1, having for example a length of about 1 meter, and whose side walls 11 determine a circulation corridor 2 extending along the longitudinal direction, and whose section is for example about 15 X 15 cm. Corridor 2 comprises a floor 21 formed by a set of transverse bars 22 which are mutually parallel and substantially

  perpendicular to the longitudinal direction of the corridor.

  At one end of the corridor, the device comprises a starting platform 3, the floor 31 of which can also be formed of bars, in the extension of the floor of the corridor. A partition wall 32 in which an opening for the passage of the rat has been made, separates the corridor from said platform. A lamp 33, for example a white fluorescent tube, makes it possible to generate aversive lighting on the starting platform, intended to encourage the rat to flee and to push it to advance in the corridor. Other aversive means can be added, for example the release of a repellent odor, shock, sound or ultrasound, electric shock, etc. Conversely, at the other end of the corridor, there is an arrival platform 4, having a solid floor 41, therefore more secure than the bars, and also separated from the corridor by a partition 42 in

  which a passage opening is provided. The platform

  arrival form is arranged so as to constitute an attractive refuge for the rat, its attractive power being able to be increased for example by dark walls, darkness, appetizing odor, sexual pheromone, social congener, food reinforcements, etc. A cover 12 partially or completely closes

the top of the box 1.

  All types of materials can be used for the various constituent elements of the box, resistant in particular to nibbling, scratches and urine, such as for example plastic, polycarbonate, etc. 0 In the example shown, all the bars 22 of the floor are located in the same horizontal plane. For example, for a corridor length of around 80 cm, there are 25 identical bars of 3 mm

  diameter and spaced 30 mm from each other.

  At a level of approximately 4 cm above the floor, several infrared sensors 5 are distributed, by

  example every 15 cm, along the length of the corridor.

  Each sensor includes a transmitter located on one side of the corridor and emitting a ray crossing the corridor and detected by a receiver located on the other side, so that the passage of the rat in the corridor interrupts the ray. Other infrared sensors 6 are similarly arranged below the level of the floor, for example at an adjustable height from 6 to 21 mm relative to the axis of the bars. The sensors 6 are grouped into sets of three sensors for example, each of these sets being located in the longitudinal direction of the corridor between two successive bars, as can be seen 3 (well FIG. 2. The sensors 6 make it possible to detect any introduction of a rat's leg between the bars, coming to cut the infrared beam of at least one sensor. Having several sensors in parallel between two bars makes detection more reliable. For each set of sensors 6, the information transmitted is transcribed into a single piece of data I0 through an "OR" door so as not to count the same drop of leg between the bars more than once

  if it cuts several beams.

  All the sensors 5 and 6 are connected to electronic cards for acquiring the data supplied by the sensors, these cards being able for example to be placed along the side walls 11 outside the corridor, and

  linked for processing information to a micro-

computer, not shown.

  The set of bars in the corridor extends the floor of the starting platform also made in the form of bars, so that the rat can somehow familiarize themselves in the starting area with the environment on which it will move before to enter the measurement zone formed by the corridor. This makes it possible to limit the risks of an excessively intense exploratory activity of the rat in the corridor, which could disturb the measurements for example by too many introductions of its head between the bars, leading to detect breaks in the light beams by the muzzle of the rat and therefore false detection of errors

leg placement.

  To make a measurement, place a rat on the floor of the starting platform. During its

  movement between the starting platform and the platform

  arrival form, we detect its position thanks to the position sensors 5 and the placement errors of its

  legs on the bars thanks to the sensors 6.

  The position sensors 5 make it possible to follow the progress of the animal and possibly calculate its speed of movement, detect its stops or its reversals. When it leaves the starting platform, the rat cuts the beam from the first sensor, 3> marked P0, which triggers the start of data acquisition, then moves to the following bars, ll successively cutting the beams of the following position sensors, marked Pi The graph in FIG. 11 illustrates a path of the animal in the successive sections of the corridor delimited by the sensors 5. We can thus observe and list the different phases of progression in forward movement MA, walking rear MR and AR stops, in successive sections, and correlate the signals from the placement sensors 6, ERR signifying a displacement with placement error and / ERR without error. Various methods can be used for data processing. One can for example directly record the data collected in a file in the form of a table, making it possible to calculate the journey times between two positions Pi and the stops or hesitation times, and to deduce therefrom an overall journey time and a time overall hesitation, and also to determine the number and duration of placement errors made in each corresponding section, and to deduce an evaluation of the total number of errors and the overall correction times. All the data collected during measurements carried out on various animals can then be processed to draw conclusions therefrom on 2) 5 the locomotor capacities of the test animals as a function of various parameters, and can in particular for this purpose be processed by various algorithms. classification, in particular using fuzzy logic. Tests carried out made it possible to show good agreement between the data provided by the device and visual surveys carried out during these tests. The device according to the invention is not limited to the device which has been described above solely by way of

example.

  In particular, the shape, the number, and the arrangement of the bars constituting the floor can be modified, as shown in particular in FIGS. 3 to 8, only by way of non-imitative complementary examples. Figure 3 illustrates a floor formed of bars regularly spaced but whose assembly is inclined relative to the horizontal, the angle of inclination may be variable, between 0 and 90, and variable along the corridor. FIG. 4 illustrates the case of bars arranged regularly but alternately at I0 two different levels. Figure 5 shows a variant arrangement, not regular. FIG. 6 illustrates the case of an arrangement in which: the spacing between

  Successive bars vary along the corridor.

  The section of the bars can also be modified, as illustrated in FIG. 7, where the bars: are flat, or FIG. 8 showing a variant with bars of rectangular section, of width and

variable spacing.

  In general, the bars can be of any circular, polygonal, etc. section, variable from one bar to another, and possibly inclined by

compared to the horizontal.

  The shape of the corridor can also be modified, for example in a U as shown in figure 9, or in a track

  substantially circular as shown in Figure 10.

  As position sensors, it is also possible to use other sensors of the light type than the infrared sensors mentioned above, for example Le of video, thermal, mechanical, volume, ohermoductile, etc. sensors. The use of vid) os) or dJe type matrix sensors may, for example, allow, for example, image or signal processing, to distinguish whether: 'is indeed a paw or for example a snout which has passed between the bars, and thus to remove possible

errors.

  The device according to the invention makes it possible (to discriminate between impaired motor or impaired explorer behavior and healthy behavior. It can therefore be used for the evaluation of the development of locomotor or exploratory deficiency in rodents after repair or rehabilitation. addition of a multidimensional algorithm based on classical or fuzzy logic makes it possible to make

the completely autonomous system.

  The device can be used with any type of rodent, for the observation of locomotor and exploratory behavior, after the following treatments: physical trauma, chemical trauma and behavioral trauma, by administration of neurotoxic, neuropharmacological products,

  neurophysiological, neurochemical, neuromuscular.

Claims (10)

  1. Device for evaluating the locomotor functions of rodents, characterized in that it comprises: - a main corridor (2) of section adapted to the size of the animal, having a floor (21) formed of urine   plurality of spaced apart transverse bars (22) and.   distributed in a longitudinal direction of the corridor, eL determining transverse openings between them, - first detection means (6), adapted 1 for detecting an introduction of an animal's leg between two of said bars, and providing in response error information for placing the legs, - second detection means (5), for determining the location of the animal in the (corridor, and providing location information, - means for processing the location information and placement error information, to deduce an evaluation of the locomotor functions   of the animal moving in the corridor.   2. Device according to claim 1, characterized (in that the first detection means (6) ontL disposed at a height of about a few millimeters at   a few centimeters under the floor (21).   3. Device according to claim 1, characterized in that the first detection means (6) comprise systems of sensors with infrared radiation, which generate transverse infrared beams or   corridor substantially parallel to the bars.   4. Device according to claim 3, characterized in that several sensor systems (6) are located between two successive bars, and the information of all the sensors located between two determined bars is transcribed in a single measurement data by means an "OR" door.   5. Device according to claim 1, characterized in that the second detection means (5) comprise infrared sensor systems, emitting beams transverse to the corridor and distributed along the   said corridor, located above the floor (21).   I () 6. Device according to claim 1, characterized   in that the corridor is substantially straight.   7. Device according to claim 1, characterized in that the device comprises a starting platform (3) located at one end of the corridor, and a   arrival platform (4) located at the opposite end.   8. Device according to claim 7, characterized in that the device is equipped with aversive means   (33) at the starting platform (3).   9. Device according to claim 7, caract-erise in that, the device is equipped with attractive means   aThe level of the arrival platform (4).   10. Method for evaluating the locomotor functions of rodents, according to which the animal is made to move in a corridor (2) on a floor (21) in the form of 0) bars (22) spaced from one another and oriented transversely to the longitudinal direction of the cetlleir, it detects during its movement its location (in the corridor as well as errors in the placement of its legs on the bars, errors signaled by sensors (6) detecting the passage of a leg in one of the spaces located between any two bars; we measure travel times between predefined positions and error times, so as to obtain data representative of the distance traveled and of the number and duration of the errors, and we deduces an evaluation of the locomotor functions as a function of   lesions or other neurological deficiencies of the animal.