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See Yourself X / Madeline Schwartzman.

A coping style (also termed behavioural syndrome or personality) is defined as a correlated set of individual behavioural and physiological characteristics that is consistent over time and across situations. This relatively stable trait is a fundamental and adaptively significant phenomenon in the biology of a broad range of species, i.e. it confers differential fitness consequences under divergent environmental conditions. Behavioural flexibility appears to be an important underlying attribute or feature of the coping style that might explain consistency across situations. Proactive coping is characterized by low flexibility expressed as rather rigid, routine-like behavioural tendencies and reduced impulse control (behavioural inhibition) in operant conditioning paradigms. This article summarizes some of the evidence that individual differentiation in behavioural flexibility emerges as a function of underlying variability in the activation of a brain circuitry that includes the prefrontal cortex and its key neurochemical signalling pathways (e.g. dopaminergic and serotonergic input). We argue that the multidimensional nature of animal personality and the terminology used for the various dimensions should reflect the differential pattern of activation of the underlying neuronal network and the behavioural control function of its components. Accordingly, unravelling the molecular mechanisms that give rise to individual differences in the coping style will be an important topic in biobehavioural neurosciences, ecology and evolutionary biology.

Philosophical transactions of the Royal Society of London. Series B. Biological sciences, 2010-12, Vol.365 (1560), p.4021-4028

Coping styles and behavioural flexibility: towards underlying mechanisms

Stressful life events generally enhance the vulnerability for the development of human psychopathologies such as anxiety disorders and depression. The incidence rates of adult mental disorders steeply rises during adolescence in parallel with a structural and functional reorganization of the neural circuitry underlying stress reactivity. However, the mechanisms underlying susceptibility to stress and manifestation of mental disorders during adolescence are little understood. We hypothesized that heightened sensitivity to stress during adolescence reflects age-dependent differences in the expression of activity-dependent genes involved in synaptic plasticity. Therefore, we compared the effect of social stress during adolescence with social stress in adulthood on the expression of a panel of genes linked to induction of long-term potentiation (LTP) and brain-derived neurotrophic factor (BDNF) signaling. We show that social defeat during adolescence and adulthood differentially regulates expression of the immediate early genes BDNF, Arc, Carp, and Tieg1, as measured by qPCR in tissue lysates from prefrontal cortex, nucleus accumbens, and hippocampus. In the hippocampus, mRNA levels for all four genes were robustly elevated following social defeat in adolescence, whereas none were induced by defeat in adulthood. The relationship to coping style was also examined using adult reactive and proactive coping rats. Gene expression levels of reactive and proactive animals were similar in the prefrontal cortex and hippocampus. However, a trend toward a differential expression of BDNF and Arc mRNA in the nucleus accumbens was detected. BDNF mRNA was increased in the nucleus accumbens of proactive defeated animals, whereas the expression level in reactive defeated animals was comparable to control animals. The results demonstrate striking differences in immediate early gene expression in response to social defeat in adolescent and adult rats.

Frontiers in behavioral neuroscience, 2011-11, Vol.5, p.72-72

Social Defeat during Adolescence and Adulthood Differentially Induce BDNF-Regulated Immediate Early Genes

The current theories of animal personality are based on the observation that individual variation in behavior and physiology appears to be consistent across contexts. Rats of the Roman selection lines have been originally selected for differences in shuttle-box behavior. Besides differences in active avoidance, these animals differ more generally in coping style. Roman high avoidance (RHA) rats show high levels of active avoidance, whereas Roman low avoidance (RLA) rats tend to respond with a more passive (i.e. freezing) response. Based on the two tier model of coping styles, we hypothesized that RHA rats would show high levels of offensive behavior and are more impulsive compared to RLA rats. We characterized animals in a two-way active avoidance task on five consecutive days. Thereafter animals were tested for their level of offensive aggression and impulsive behavior. The level of offensive aggression was examined in a standard resident-intruder paradigm. Furthermore, we tested aspects of impulsivity in an unpredictable operant conditioning paradigm (variable interval-15 schedule) for food reinforcement and during extinction of lever press behavior. We show that RHA rats are indeed characterized by high levels of two-way active avoidance in a shuttle-box paradigm. Surprisingly, the level of offensive aggression was higher in RLA compared to RHA rats. Consistent with the coping style interpretation, the number of lever presses in the VI-15 schedule for food reinforcement was higher in RHA rats compared to RLA rats. During a session of frustrating non-reward, RHA rats were more persistent. Taken together, results of the two-way active avoidance task and VI-15 performance in rats of the Roman selection lines fit with the two tier model of coping styles. Unexpectedly, the level of offensive aggression does not match with this model.

Behavior genetics, 2013-05, Vol.43 (3), p.220-226

Correlated Behavioral Traits in Rats of the Roman Selection Lines

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See Yourself X / Madeline Schwartzman.

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Coping styles and behavioural flexibility: towards underlying mechanisms

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Social Defeat during Adolescence and Adulthood Differentially Induce BDNF-Regulated Immediate Early Genes

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Correlated Behavioral Traits in Rats of the Roman Selection Lines

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