Freezing behavior is measured by direct observation, scoring an animal as either freezing or active per interval of time, usually every 5–10 sec ( Fanselow 1990 Paylor et al.

(1994) define freezing as the absence of any movement except for respiratory-related movements. In mice, freezing is a common and easily measured response used as an index of fear conditioning ( Blanchard and Blanchard 1988 Graef 1994). Fear responses are elicited by previously neutral conditioned stimuli, such as a distinctive chamber (context) or auditory cue after the conditioned stimulus has been paired with an aversive unconditioned stimulus, such as footshock. Automation of freeze scoring would significantly increase efficiency and reliability of this learning and memory test.Įmotional responses such as fear are rapidly acquired through classical conditioning. In addition, the use of computer-scored freezing of 199 (BALB/cJ × C57BL/6J)F 2 mice enabled us to detect a suggestive gender-dependent chromosomal locus for contextual fear conditioning on distal chromosome 8 by QTL analysis. Previously reported strain differences between C57BL/6J and DBA/2J in context-dependent fear conditioning were also detected by the computer-based system. The different computer measures obtained during contextual fear conditioning tests showed high correlations with hand-scored freezing r values ranged from 0.87 to 0.94. We report the use of a computerized method based on latency between photobeam interruption measures as a reliable scoring criterion in mice. A technical limitation, particularly for genetic studies, is the method of direct observation used for quantifying this response, with the potential for bias or inconsistencies. The most commonly measured mouse behavior in fear conditioning tests is freezing.

Any-maze freezing nature mouse