Laboratory Analysis of Behavioral Effects of Drugs of Abuse in Rodents - Drugs of Abuse: Neurological Reviews and Protocols - page 465

breaks using software supplied by the photobeam manufacturer. “Crossovers”
are calculated by dividing the chamber into quadrants, and tabulating a
“crossover” each time the rodent enters one of the predefined quadrants
subdividing the chamber. Again, this measure may generally be calculated from
the pattern of photobeam breaks using software supplied by the manufacturer.
The calculated locomotion measure may be validated by videotaping a
session, and replaying the session on a video monitor with masking tape placed
vertically and horizontally bisecting the video image of the behavioral chamber.
The locomotor measure calculated by computer is compared to the locomotor
measure determined manually in the test session. We have employed manual
observation of rodents treated with increasing amphetamine doses (0.1, 2.5, 5,
and 10 mg/kg) to validate computer-generated locomotion measures. Because
“distance traveled” and “crossovers” are not identical measures, choice of a
particular locomotion measure will depend on the given study and specifi c
drug of abuse studied.
3.2. Stereotypical Behaviors
Stereotypy refers to repetitive, perseverative patterns of behavior. Measure-
ment of stereotypy can be accurately determined only by direct observation
of the animal, and cannot be calculated from analysis of photobeam breaks.
This translates into a labor intensive undertaking for experiments analyzing
the effect of drugs of abuse on stereotypy.
A variety of rating scales to estimate stereotyped behaviors quantitatively
have been described (1-4) . In practice, we have found measurement of the
percentage of time engaged in stereotyped behavior to be the simplest method
of analyzing stereotyped behavior (5) . Observers rate behavior for 30 s of
each 3-min interval ( see Note 2 ). The percent of each 30-s interval engaged in
stereotyped behaviors including focused sniffi ng, repetitive chewing, licking,
or biting, or repetitive head and limb movements is determined (5) .
4. Notes
1. The specifi c plans for equipment housing animals will in almost all cases require
approval of the local Institution Animal Care and Use Committee. It is highly
recommended to review plans with a representative of the committee at an early
stage of the planning process.
2. Measures of stereotyped behavior are subjective. It is important that raters be
blind to animal treatment. For best results, two raters should score animals
independently and a measure of inter-rater reliability established. In addition,
stereotypy scores should be compared to automated measures of data collection
(such as locomotor measurement) to ensure that the independent measurements
are consistent (i.e., locomotion goes down as stereotypy goes up).