Detection of a temporal structure in the rat behavioural response to an aversive stimulation in the emotional object recognition (EOR) task.

Aim of the research was to investigate whether a temporal structure could be detected in the behavioural response to an aversive stimulation. A fear-related memory task was used in rats, placed in a modified version of the Novel Object Recognition task known as Emotional Object Recognition task, i.e. a behavioural assay that orbits around the declarative memory for an aversive experience. To this purpose, twelve male Wistar rats, divided in two groups (Control and Aversive memory), observed after 4 h (OR4h) and after 24 h (OR24h) from the delivery of an aversive stimulation, associated to a specific object, were used. Data were evaluated both in terms of conventional quantitative approaches and by means of T-pattern analysis, namely a multivariate technique able to unveil the temporal structure of behaviour and the relationships amongst the behavioural items in time. Results evidenced several changes between groups and over time as well. Mean occurrences and mean durations showed significant differences between OR4h and OR24h sessions and between Control and Aversive memory groups for behavioural items of Exploration, Object-related aversion and Immobility. T-pattern analysis revealed important changes of behavioural variability, complexity and repetitiveness, (i.e., the three main qualitative features of T-patterns) in the Aversive memory group. These outcomes highlight a simpler and linear behavioural profile, focused only on specific sequences of particularly repetitive events. Overall, the present study demonstrates a) the presence of a temporal organization of fear-related behavioural events and b) the influence of learning on the modifications observed over time.

Combining Quantitative and Qualitative Data in the Study of Feeding Behavior in Male Wistar Rats.

The first step in a behavioral study is represented by the organization of a suitable ethogram, that is, a formal description of individual components of the behavior. Then, each component of such a behavioral repertoire can be quantified (e.g., how many times it occurs, its duration, percent distribution, latency, etc.). However, it is our contention that the possibility to describe the behavior of a living being by means of hundreds or even thousands of numbers concerning isolated components, disjointed from the comprehensive behavioral architecture, does not imply the possibility to use those numbers to reconstruct the meaning of behavior. Such a level of comprehension requires a qualitative approach based on the analysis of behavioral structure and its underlying dynamics. By means of synergic utilization of quantitative and qualitative data a more complete description of a given behavior becomes available. In present study we discuss results obtained from observations of feeding behavior in two groups of male Wistar rats: a control group, under standard diet, and a second group, under hyperglycidic one. Results have been presented both in terms of quantitative evaluations and in terms of structural/qualitative ones, the latter obtained by means of T-pattern detection and analysis. As to quantitative results, mean durations showed a significant reduction of Walking and Feeding and an increase of Hind-Paw Licking and Body Grooming; concerning mean occurrences, a significant increase of Front-Paw Licking, Hind-Paw Licking, and Body Grooming was present; percent distributions showed significant reductions for Walking and Feeding and a significant increase for all grooming activities. As to qualitative assessments, T-pattern analysis unveiled a clear-cut behavioral reorganization induced by the hyperglycidic diet. If on the one hand, 50 different T-patterns were detected in subjects under standard diet, on the other hand, 703 different T-patterns were discovered in animals under hyperglycidic treatment, with a highly significant increase of mean lengths and a significant reduction of mean occurrences of T-patterns. Synergic evaluation of results in terms of quantitative and qualitative aspects shows, in rats fed with hyperglycidic diet, an increased anxiety condition, likely dependent on food-related stimuli and suggestive of a pervasive craving-related behavior.