Automated video analysis system reveals distinct diurnal behaviors in C57BL/6 and C3H/HeN mice.

Advances in rodent behavior dissection using automated video recording and analysis allows detailed phenotyping. This study compared and contrasted 15 diurnal behaviors recorded continuously using an automated behavioral analysis system for a period of 14 days under a 14/10 light/dark cycle in single housed C3H/HeN (C3H) or C57BL/6 (C57) male mice. Diurnal behaviors, recorded with minimal experimental interference and analyzed using phenotypic array and temporal distribution analysis showed bimodal and unimodal profiles in the C57 and C3H mice, respectively. Phenotypic array analysis revealed distinct behavioral rhythms in Activity-Like Behaviors (i.e. walk, hang, jump, come down) (ALB), Exploration-Like Behaviors (i.e. dig, groom, rear up, sniff, stretch) (ELB), Ingestion-Like Behaviors (i.e. drink, eat) (ILB) and Resting-Like Behaviors (i.e. awake, remain low, rest, twitch) (RLB) of C3H and C57 mice. Temporal distribution analysis demonstrated that strain and time of day affects the magnitude and distribution of the spontaneous homecage behaviors. Wheel running activity, water and food measurements correlated with timing of homecage behaviors. Subcutaneous (3 mg/kg, sc) or oral (0.02 mg/ml, oral) melatonin treatments in C57 mice did not modify either the total 24 h magnitude or temporal distribution of homecage behaviors when compared with vehicle treatments. We conclude that C3H and C57 mice show different spontaneous activity and behavioral rhythms specifically during the night period which are not modulated by melatonin.

Function of dog's auditory cortex in tests involving auditory location cues and directional instrumental response.

Twenty one dogs, distributed into four groups, were trained pre-operatively in differentiation of auditory location or frequency cues. In each group instrumental responses, reinforced by food consisted in placing by the animal its right paw on the side levers. The first differentiation, go-left, go-right task with two location cues, required the animal to place its paw on the lever opposite to the source of the cue. The second differentiation task with the same location cues required placing the paw on the lever located close to the cue. The third task, involving 700 Hz vs. 1,000 Hz tone, required responding to one lever to the presentation of one tone and responding to the opposite lever to the presentation of the other. The last task was a symmetrically reinforced go, no-go differentiation with, again, auditory location cues: the animals were trained to place the paw on a lever to one location cue and to withhold this response to the other location cue. Bilateral ablation of the primary auditory cortex produced a considerable impairment of the performance of the two go-left, go-right tasks involving location cues. The go-left, go-right task employing frequency cues, and the symmetrically reinforced go, no-go task with location cues, were only slightly disturbed by this lesion.

Function of cat's caudate nucleus in tasks involving spatial discontiguity between location of cue and response.

Cats were trained on go-left, go-right tasks with auditory frequency (F) or auditory location cues. The latter were used either with cue-response spatial discontiguity (LspD) or contiguity (LspC). Bilateral lesions located in the ventral segment of the caudate produced severe impairments on F and LspD tasks performance. Similar lesions, however, had no effect on the performance of the LspC task. Our findings show that spatial discontiguity between the location of cue and response is a crucial factor producing deficit on spatial tasks performance.

Effects of prefrontal lesions on left leg-right leg differentiation to nondirectional acoustic cues in dogs.

Twenty five dogs were trained preoperatively in left leg- right leg differentiation to nondirectional acoustic cues. Removal of the medial precruciate cortex as well as the proreal or orbital cortex together with underlying fibers did not affect performance of the task, whereas lesions which involved the fibers underlying the medial precruciate cortex produced more or less pronounced, yet moderate impairment. Comparison between impairment described in this paper and that obtained following similar lesions in earlier experiment with directional cues indicates that fibers underlying the medial precruciate cortex are of greater importance when directional cues are involved in task.

Prefrontal cortex and manipulatory go left-go right differentiation to acoustic directional cues in dogs.

In 20 dogs the manipulatory go left – go right differentiation to acoustic directional cues was elaborated. All dogs received total prefrontal, or dorsolateral (total or partial) or medial (total or partial) cortical ablations. All total ablations markedly affected performance of the task, whereas the partial removals produced moderate or no impairment. Thus, both the dorsolateral and medial prefrontal cortex are involved in this type of differentiation.

The magnet reaction, a symptom of prefrontal ablation.

After bilateral ablation of the medial precruciate cortex in dogs and cats, or dorsolateral prefrontal cortex in monkeys, the animals approach the source of the conditional stimulus (CS) indicating availability of food either before or instead of approaching the food itself. This behavior is designated the "magnet reaction". It is particularly evident when the source of the CS is located in a direction different from that taken to reach the food. Lesions elsewhere in the frontal lobes do not produce this effect.

Effects of prefrontal lesions on left leg-right leg differentiation in dogs.

Twenty five animals trained in the left leg-right leg differentiation were given orbital, proreal or medial precruciate lesions. Pure cortical ablations did not affect the task whereas these deep lesions involving the bundle of fibers inside the prefrontal region caused severe deficit. The medial lesions (superficial and deep) produced disinhibition of the intertrial reactions. The nature of the deficit in the differentiation and the relation between this deficit and the disinhibition is discussed.