A Macintosh Computer System for Collecting and Analyzing Rodent Sexual Behavior.

James L. Weed
Department of Psychology, University of Georgia, Athens, GA 30602

James L. Boone
Institute of Ecology, University of Georgia, Athens, GA 30602

Abstract

We present a Macintosh based computer system for collection and analysis of rodent sexual behavior. Two computer programs are presented. The first is an entirely generalizable real time data collection program that records any keyboard or keypad inputs (e. g. user defined behavior codes) and their time of occurrence. The second is somewhat generalizable; we use it to analyze frequencies, durations and latencies relative to a copulatory series, (including mounts, intromissions and ejaculations). To our knowledge, these are the first such programs available on the Macintosh platform.

Keywords: Macintosh microcomputer, male sexual behavior, rodents, event recording, hamster

Introduction

In recent years, several microcomputer programs have been developed for the collection and analysis of rodent sexual behavior (3, 4, 5, 7). These authors have shown that computer programs can simplify behavioral analysis primarily through the reduction of hand transcription, but also through automated data analysis. We present a Macintosh based system that differs from the previous programs in two ways. First, these programs run on a Macintosh, and as these computers become more common, there is a need for programs that run on this platform. Second, most of the previous programs only record data on specific behaviors (but see 5); our data collection program is entirely generalizable to collecting any number of behaviors over any length of time.

Methods

Hardware

The computers used in this work were Macintosh SE and SE/30s equipped with hard drives and a minimum of 1 megabyte of random access memory (RAM). However, due to the standardized Macintosh environment, our programs run under any model that runs Microsoft QuickBASIC (Microsoft Corporation, Redmond, WA). Currently, this includes MacPlus and later models, including computers running System 7.

Software - Data Recorder

We have written two programs in Microsoft QuickBASIC. The first is a generalized data recorder, and the second is a data analysis program. The generalized data recorder accepts any keyboard or keypad input and applies a time stamp when the enter or return keys are depressed (Fig. 1). This system allows for recording simultaneous behaviors with user

defined start and stop codes. For instance, if an animal urinates while feeding, both behaviors and their durations can be recorded. This could be adapted for recording the behavior of several animals at the same time. The data recorder is very fast and can record several observations per second to the nearest 0.1 seconds.

There are no time limits or other constraints placed on the operator. A user definable timer can alert the user (audio or visual) at any fixed time interval or at a specified time following a pre-defined behavior code. In the present application, that of recording the copulatory behavior of Syrian golden hamsters (Mesocricetus auratus), the criterion for test termination is fifteen minutes without an intromission (2). The data recorder program accesses the clock, giving a running tally of total duration while simultaneously restarting a countdown timer each time the defined behavior code is recorded. The timer function can be redefined for a particular data (behavioral) recording application, such as all occurrence, instantaneous, scan samples, or focal animal observations (1).

The program outputs a comma delimited text (ASCII) file that contains the observation and the time that each observation was entered. Editing is allowed within the data recorder. Incorrectly keyed behavior codes can be deleted or corrected immediately if desired. Alternatively, error codes (e. g., "99" or "delete observation 3 lines up") can be entered which allows for editing the data at a later time with any word processor. At startup, the data recorder requires that header information be input. This information is used for identifying the data file both in the output file and in files created by the data analysis program.

Software - Data Analysis

In the present use of the data recorder, only one pair of copulating hamsters is observed at a time. This is a constraint on the analysis program, i.e., data are summarized and analyzed for one pair of subjects each time. Our data analysis program reads the data file and summarizes the following behaviors by copulatory series (2): ejaculation frequency, mount latency, intromission latency, lordosis latency, total lordosis time, series number, series duration, frequency of intromissions and mounts, ejaculation latency, post-ejaculation interval, mean inter-intromission interval, lordosis duration, and frequency counts of other behaviors (Fig. 2 ). All other behaviors recorded (e. g. urinating, grooming, female-specific acts, etc.) are also tabulated relative to these intervals. Output can be directed to the screen, a text file, or a printer. Because our studies employed a complex experimental design, we did not write programs for statistical analysis or graphical display, but rather transported program outputs to commercially available statistical programs. Presently we use Microsoft Word, Microsoft Excel (Microsoft Corporation, Redmond, WA), and Systat (Systat, Inc., Evanston, IL) to edit and analyze the data. No complex data transformations are necessary.

Discussion

The main benefit of our data recording scheme over previous ones is that any event can be recorded. Therefore, an observer can record anything, regardless of whether that behavior is the focus of the current study. This permits the collection of large amounts of data that need not interfere with the current study, while preserving those observations for future analyses. Our analysis program overlooks behaviors not relevant to our study, although the program summarizes these other behaviors by ejaculation interval. By appropriately defining events, these programs could be used by researchers interested in other time dependent questions. So long as events are measured relative to some specific event, these programs could be quite general. For instance, if picking up a food item were the pivotal event, a researcher could analyze how long it took for an animal to pick up a food item, and what it did, and for how long, between picking up additional food items. If female copulatory behavior were the focus of a study, parameters could be redefined to analyze these patterns (6).

References

1. Altmann, J. Observational study of behavior: sampling methods. Behaviour. 49:227-267; 1974.

2. Bunnell, B. N.; Boland, B. D.; Dewsbury, D. A. Copulatory behavior of golden hamsters (Mesocricetus auratus). Behaviour. 61:180-206; 1977.

3. Claro, F.; Del Abril, A.; Segovia, S.; Guillamon, A. SBR: A computer program to record and analyse sexual behavior in rodents. Physiol. Behav. 48:489-493; 1990.

4. Hendrie, C. A.; Bennett, S. A microcomputer technique for the detailed behavioural, and automatic statistical, analysis of animal behaviour. Physiol. Behav. 32:865-869; 1984

5. Holmes, G. M.; Holmes, D. G.; Sachs, B. D. An IBM-PC based data collection system for recording rodent sexual behavior and for general event recording. Physiol. Behav. 44:825-828; 1988.

6. McClintock, M. K.; Adler, N. T. The role of the female during copulation in wild and domestic norway rats (Rattus norvegicus). Behaviour. 67:67-96; 1978.

7. Rakerd, B.; Brigham, D. A.; Clements, L. G. A microcomputer-based system for recording and analyzing behavioral data regarding the sexual activity of male rodents. Physiol. Behav. 35:999-1001; 1985.

Figures

Figure 1. Computer display of the data recorder. Entries include behavior codes (4, 5, and 45), time when the behavior code was entered, and miscellaneous notes concerning behaviors not previously defined with behavior codes.

Figure 2. Computer display of output from the data analysis program. The top five lines identify the individuals tested, drug doses, and test date. The body of the table lists behavior frequencies, durations, and latencies by series. EF = ejaculation frequency, IF = intromission frequency, MF = mount frequency, EL = ejaculation latency, PEI = post-ejaculation interval, MIII = mean inter-intromission interval, FLD = frozen lordosis duration, WLD = walking lordosis duration.