Individualized and Clinically Derived Stimuli Activate Limbic Structures in Depression: An fMRI Study

In the search for neurobiological correlates of depression, a major finding is hyperactivity in limbic-paralimbic regions. However, results so far have been inconsistent, and the stimuli used are often unspecific to depression. This study explored hemodynamic responses of the brain in patients with depression while processing individualized and clinically derived stimuli.Eighteen unmedicated patients with recurrent major depressive disorder and 17 never-depressed control subjects took part in standardized clinical interviews from which individualized formulations of core interpersonal dysfunction were derived. In the patient group such formulations reflected core themes relating to the onset and maintenance of depression. In controls, formulations reflected a major source of distress. This material was thereafter presented to subjects during functional magnetic resonance imaging (fMRI) assessment.Increased hemodynamic responses in the anterior cingulate cortex, medial frontal gyrus, fusiform gyrus and occipital lobe were observed in both patients and controls when viewing individualized stimuli. Relative to control subjects, patients with depression showed increased hemodynamic responses in limbic-paralimbic and subcortical regions (e.g. amygdala and basal ganglia) but no signal decrease in prefrontal regions.This study provides the first evidence that individualized stimuli derived from standardized clinical interviewing can lead to hemodynamic responses in regions associated with self-referential and emotional processing in both groups and limbic-paralimbic and subcortical structures in individuals with depression. Although the regions with increased responses in patients have been previously reported, this study enhances the ecological value of fMRI findings by applying stimuli that are of personal relevance to each individual's depression

Measuring aggressiveness in growing pigs in a resident-intruder situation

International audienceStudies concerning aggression after mixing unfamiliar pigs have shown that there is a great variability in the levels of aggression shown by individual pigs. This study examined whether individual aggressiveness can be measured in a resident-intruder situation and whether it is a stable characteristic of individuals, which does not simply reflect the age or sex class of the animal. These latter requirements are of fundamental importance in establishing the existence of individual personality or temperament characteristics in animals. The research was carried out in three datasets, with a total of 218 pigs, females and entire males, at the age of 7 and 11 weeks, For the test, individual pigs were isolated in one half of their home pen, and an intruder pig was introduced. This pig was 2-3 weeks younger than the resident pig. The time from when the resident first made contact to when it attacked the intruder pig was used as a measure of aggressiveness. If the resident did not attack, the test was terminated after 3.5 min. The test was repeatable across two consecutive days as well as across four weeks. Aggressiveness was found to be unrelated to characteristics of the test pigs, such as sex, age, body weight and body weight ranked within litter. Attack latency was not affected by the sex of the intruder pig, If the intruder was less than half the body weight of the test pig, it was less likely to be attacked. Considerable variation was found within as well as between litters, The importance of the nature of the test arena, and implications of the duration of the test are discussed, Using attack latency as a measure of aggressiveness and a relatively short time limit, the test provides a useful tool for measuring aggressiveness without compromising the welfare of the animals involved