A system for automatic recording and analysis of motor activity in rats

We describe the design and evaluation of an electronic system for the automatic recording of motor activity in rats. The device continually locates the position of a rat inside a transparent acrylic cube (50 cm/side) with infrared sensors arranged on its walls so as to correspond to the x-, y-, and z-axes. The system is governed by two microcontrollers. The raw data are saved in a text file within a secure digital memory card, and offline analyses are performed with a library of programs that automatically compute several parameters based on the sequence of coordinates and the time of occurrence of each movement. Four analyses can be made at specified time intervals: traveled distance (cm), movement speed (cm/s), time spent in vertical exploration (s), and thigmotaxis (%). In addition, three analyses are made for the total duration of the experiment: time spent at each x–y coordinate pair (min), time spent on vertical exploration at each x–y coordinate pair (s), and frequency distribution of vertical exploration episodes of distinct durations. User profiles of frequently analyzed parameters may be created and saved for future experimental analyses, thus obtaining a full set of analyses for a group of rats in a short time. The performance of the developed system was assessed by recording the spontaneous motor activity of six rats, while their behaviors were simultaneously videotaped for manual analysis by two trained observers. A high and significant correlation was found between the values measured by the electronic system and by the observers.     

Some simple Apple II software for the collection and analysis of observational data

Two general-purpose software packages for collecting and analyzing observational data from a variety of settings are discussed. One package is designed for coding mutually exclusive behavioral states using the Apple’s keyboard as an input device. The other is designed to monitor temporally overlapping behaviors, and it makes use of the Apple II’s built-in game-control button inputs to indicate up to three behavioral states that may occur simultaneously.     

Harmonic analysis of a complex motor behavior

This study deals with the learning of a complex motor task. The example used is rock climbing, where the subject's motricity is highly constrained by the natural environment. The working hypothesis is that the sensorimotor system searches for behavioral solutions characterized by minimal energy expenditure in the dissipation of forces. Harmonic systems — which satisfy this requirement — are used as models for testing the source signal defined by the acceleration curve at the learner's center of gravity. It is shown that only the dynamics of an expert's motor behavior are harmonic, while those of a beginner are stochastic (or chaotic). It is also shown that for experts, the process of adaptation to environmental constraints involves the relaxation of the dynamics and the ensuing emergence of a stable state which corresponds to a quasi-periodic attractor. A harmonic analysis is used to distinguish the environmental and intrinsic components of the behavioral dynamics, shown to result from the coupling of these two components via resonance.     

Temporal compatibility in dual motor tasks II: Simultaneous articulation and hand movements

Simultaneous articulation did not interfere with hand responses if the responses shared the same time period. Otherwise there was marked interference even after performance had stabilized with practice. These results generalized previous findings for simultaneous left-and right-hand responses (Klapp, 1979) to show that even highly distinctive responses can be generated in parallel only if they have compatible timing.     

On-line versus off-line control of rapid aiming movements

Recent studies have shown the importance of visual feedback during the rapid initial phase of aiming movements for the control of direction (e.g., Bard, Paillard, Fleury, Hay, & Larue, 1990; Blouin, Teasdale, Bard, & Fleury, in press; Teasdale, Blouin, Bard, & Fleury, 1991). In most of these studies, visual feedback conditions were presented in blocked sessions. Consequently, higher-order processes (e.g., feedforward and/or learning processes), along with on-line processing of visual feedback, might have contributed to the better accuracy found when subjects had visual feedback of only the initial portion of the movements (compared with movements without visual feedback). To test this possibility, we studied subjects' performance of rapid arm movements under different types of presentation (random, precued, and blocked) of the visual feedback conditions of the trajectory (no vision, initial portion only, and vision of the entire trajectory). Directional errors were larger in the no-vision condition than in both conditions with visual feedback. There were no differences among the presentation conditions, suggesting that on-line processing of visual information contributed to the control of the arm movements.     

3-D graphics animation program for the Apple II

A graphics design program for creating point-light displays of transforming 3-D objects is presented. This program was written for an Apple II microcomputer interfaced to a Texas Instruments TMS 9918A video display processor. In contrast to other 3-D design programs, it uses individual point-lights undergoing circular trajectories as a design primitive. An editor enables the user to enter and edit specific motion parameters for defining the parallel projection of as many as 16 point-lights on the screen. These parameters are then used to calculate and store in an animation list the screen positions of each point-light for each frame. Number of frames to be displayed and display rate are user defined.     

On-line trajectory modifications of planar,goal-directed arm movements

Sometimes a goal-directed arm movement has to be modified en route due to an unforeseen perturbation such as a target displacement or a hand displacement by an external force. In this paper several aspects of that modification process are addressed. Subjects had to perform a point-to-point movement task on a computer screen using a mouse-coupled pointer as the representation of the hand position. Trajectory modifications were imposed by unexpectedly changing the position of the target or by changing the relation between mouse and screen pointer.In the first series of experiments, we examined how often a trajectory is updated. Here, trajectory modifications were imposed by unexpectedly changing the normal relation between mouse and pointer to a shear-like relation, where a percentage of the forward/backward position of the hand was added to the pointer position in the left/right direction. Withdrawal of visual feedback during the movement revealed that trajectories were updated at interval times shorter than 200 ms. From the similarity with experiments where the original relation between mouse and pointer was restored during the movements, we conclude that motor plans are updated on-line to move the hand from its current perceived position to the target.In a second series of experiments, we studied whether a continuous change in target position yields similar trajectory modifications as a continuous hand displacement. To mimic the latter perturbation, we used the above-mentioned distortion of the mouse-pointer relation. We found that the resulting hand paths did not differ for the two visual perturbations and conclude that the perturbed, goal-directed movements are modified in a consistent way, irrespective of whether the position of the target or hand was perturbed. Simulations of the experimental data with a kinematic reaching model support this conclusion.     

The analysis of multiphasic signals with the Apple II/FIRST microprocessor system

An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning from uniphasic response signals (Scandrett & Gormezano, 1980). The present paper covers an expansion in the capabilities of the system by the development of a multiphasic signal analysis algorithm written in FIRST, an interactive, high-level, dictionary-based language. The program provides unprecedented efficiency, sensitivity, and flexibility in the analysis of multiphasic analog response signals in classical conditioning experiments. Moreover, the program has the potential to analyze even more complex signal patterns.     

Segmentation and coupling in complex movements

In two experiments we explore the structure of complex sequences of drawing movements. We find that in these movements a single parameter--the velocity gain factor--relates the geometrical and kinematic aspects of the movement trajectory via a two-thirds power law. In Experiment 1 we investigate the relation between the velocity gain factor and the linear extent of the trajectory. In Experiment 2 we demonstrate that the gain factor provides a criterion for segmenting the movement into distinct units of motor action, and we investigate the effects of the speed of execution on this segmentation. A theoretical analysis shows that the results of both Experiments 1 and 2 can be given a unitary interpretation by assuming a coupling function of variable strength between segments. The general problem of representing motor programs is discussed within this theoretical framework.     

On-line analysis of the GSR

This study reports the use of the λ, a measure of sequential dependency developed by Lathrop (1964) in connection with electrodermal activity. Thirteen female subjects, ranging in age from 19 to 53, participated in a simple repeat-stimulus habituation experiment: GSR data in percent-change and λ were compared. A high, positive correlation was obtained. Consequently, the use of λ is advocated because it shows both initial value and sequential dependency and meets the criteria for analysis based on the probability of statistics such ast andF.