Development Of Behavioral Inhibition Research Articles

Approach, avoidance, and the detection of conflict in the development of behavioral inhibition

Motivation has played an integral role in understanding personality development. Two motivational systems, one associated with seeking reward (approach motivation) and one associated with avoidance of threat (avoidance motivation), have been theorized to represent individual differences in behavioral responses to the environment. However, contextual factors, particularly those with a high degree of novelty, ambiguity, and unpredictability, may simultaneously activate both systems, thereby causing approach–avoidance conflict. The resulting behavior, commonly called inhibition, is characterized by an inability to engage in motivated, goal-directed behavior and is theorized to reflect a core component of anxiety. A form of inhibition observed in childhood, behavioral inhibition (BI), is a relatively stable temperamental profile characterized by negative affect in response to unfamiliar and unpredictable contexts and is a risk factor for anxiety. Our review draws from findings in clinical and cognitive neuroscience to argue that BI reflects an increased sensitivity of both approach and avoidance motivational systems, thereby increasing the likelihood of approach–avoidance conflict within the context of unfamiliar or unpredictable stimuli and environments. Such motivational conflict activates neural systems associated with conflict monitoring, which leads to increases in arousal (e.g., sympathetic nervous system activity) and onlooking behavior, two commonly observed characteristics of childhood BI.

The Development of Behavioral Inhibition in Chinese Children From 2 to 7 Years of Age

Behavioral inhibition is one of the most important dimensions of temperament that has a pervasive and long-term impact on individual personality and social functioning.The present study examined the stability of behavioral inhibition,based on laboratory observations,in a sample of children in China from two to seven years of age. The participants in the initial study included 124 children at two years.Among them,103 participated in a follow up study at four years,and 100 at seven years.There were 113 children who took part in the laboratory observation at least once at 2,4 and 7 years,and the complete longitudinal sample consisted of 89 children. The results indicated that the stability of behavioral inhibition of Chinese children from 2 to 7 years was generally weak.From 2 to 7 years,31.5%(28) of the children were classified as the stable group and 68.5%(61) as the unstable group.With the increase of age from 2 to 7 years,there was a tendency for children in the extremely inhibited and uninhibited groups to change toward the middle group.However,from 2 to 4 years,behavioral inhibition in the extreme groups was more stable than that in the middle group.There was no sex difference in the behavioral inhibition from 2 to 7 years.The results might be related to the influence of the macro-level social and cultural changes in the society.

Effects of a brief sensorimotor training on the development of behavioral inhibition in the mouse

In the young C57Bl6 mouse, the hyperexcitability phase (`pop-corn' stage) which normally occurs around the 16–18th postnatal day and lasts 3–6 days, was greatly shortened by an intensive sensorimotor training when the `pop-corn' stage appeared. It was prevented when the animals were trained for 4 days before it appeared. This might suggest, at least in part, that an early short duration sensorimotor training increased the rate of maturation of the inhibitory systems that sustain the development of the motor behavior.

Relative contributions of pituitary -Adrenal hormones to the ontogeny of behavioral inhibition in the rat

Recent investigations revealed that adrenalectomized (ADX) rat pups exhibit deficits in behavioral inhibition. Furthermore, administration of exogenous corticosterone (CORT) restores behavioral inhibition in ADX pups. Although these studies suggest that CORT has an important role in the development of behavioral inhibition, the relative behavioral effects of elevated pituitary hormone secretion induced by ADX are not known. Therefore, experiments were conducted to assess the potential behavioral effects of elevated adrenocorticotropin (ACTH) secretion induced by ADX and to further evaluate the contribution of endogenous CORT to the development of behavioral inhibition. In Experiment 1., we verified that 10-day-old ADX rats exhibit high levels of plasma ACTH throughout the preweaning period associated with the development of behavioral inhibition. In Experiment 2, 10-day-old pups were hypophysectomized (HYPOX) and ADX and were compared behaviorally to sham-operated controls on day 14. When tested in the presence of an anesthetized unfamiliar adult male rat, HYPOX + ADX pups exhibited low levels of freezing accompanied by ultrasonic vocalizations. These pups also had reduced concentrations of plasma ACTH and CORT. In Experiment 3, 10-day-old pups were HYPOX and tested for behavioral inhibition on day 14. In comparison to sham-operated controls, HYPOX rats exhibited significantly lower levels of freezing and had reduced plasma concentrations of ACTH and CORT. Results demonstrate clearly that deficits in freezing occur even in the presence of low plasma ACTH concentrations. Therefore, elevated secretion of pituitary hormones is not a major factor that contributes to the ADX-induced deficits in behavioral inhibition. In addition, results considerably strengthen the contention that endogenous adrenal steroids have a prominent role in the development of neural pathways regulating the expression of behavioral inhibition.

Organizing action of corticosterone on the development of behavioral inhibition in the preweanling rat

Altricial rat pups develop the ability to freeze and to terminate their emission of ultrasonic vocalizations when exposed to an unfamiliar adult male rat. This developmental competence in expressing behavioral inhibition is impaired when rat pups are adrenalectomized (ADX) on postnatal day 10, a period prior to the emergence of behavioral inhibition. Adrenalectomy, however, fails to induce similar behavioral deficits when performed after behavioral inhibition has developed. Results suggest that adrenal steroids are involved in promoting the development but not the activation of behavioral inhibition. To critically test this hypothesis, four groups of rats were adrenalectomized on day 10 and tested for behavioral inhibition on day 18. Prior to testing, one group of rats received daily s.c. injections of vehicle whereas another group was treated with daily injections of 3.0 mg/kg of corticosterone (B). The other two groups of rats received daily B injections on only days 10–13 or days 14–17. Results indicated that ADX rats treated with B only on days 10–13 as well as throughout exhibited significantly higher levels of freezing than the other two treatment groups. In order to evaluate whether the behavioral inhibitory deficits produced by ADX at 10 days of age are due to a delayed insensitivity to the 3.0 mg/kg dose of B, day 10 pups were ADX and injected on days 14–17 with doses of B as high as 12 mg/kg. When tested for behavioral inhibition on day 18, these high doses of B were found to be ineffective in potentiating freezing above the level of vehicle-treated rats. Together, results suggest that prior to the end of the second postnatal week endogenous adrenal steroids and in particular B, are critically involved in developmental changes necessary for the eventual species typical expression of behavioral inhibition.

Intracranial action of corticosterone facilitates the development of behavioral inhibition in the adrenalectomized preweanling rat.

We tested the hypothesis that in preweanling rats central administration of exogenous corticosterone (CORT) is sufficient to facilitate the development of behavioral inhibition. 28-gauge cannulae containing varying concentrations of CORT (0, 25, 50 and 100%) were implanted unilaterally into the lateral ventricles of 9-day-old rat pups. After a 24-h postoperative recovery period, pups were adrenalectomized. At 14 days of age, pups were tested for behavioral inhibition which consisted of removing the pup from the nest and exposing it to an unfamiliar adult male rat. Pups implanted with cannulae containing 0, 25 and 50% concentrations of CORT spent significantly less time in freezing postures than pups implanted with cannulae containing 100% CORT. These freezing pups also tended to emit fewer ultrasonic vocalizations than pups in the other three implant conditions, albeit the level obtained was not statistically significant. RIAs indicated that, in general, hormone-filled cannulae produced no detectable concentrations of plasma CORT on the day of the test or on days preceding testing. Results suggest that in the early postnatal period endogenous CORT acts centrally to facilitate the development of neural pathways involved in the ontogenetic expression of behavioral inhibition.

Emerging cholinergic mechanisms and ontogeny of response inhibition in the mouse.

Mice, 7, 11, 15, 19, and 85-115 (adult) days of age, served as subjects in experiments assessing effects of anticholinergics on the development of behavioral inhibition. The centrally active anticholinergic scopolamine produced a dose-dependent elevation in locomotor activity in 19-day-old and adult mice. Acquisition and retention of a step-off passive avoidance response (PAR) was initially studied in nondrugged subjects. Mice as young as 7 days of age learned and retained the PAR for 1 hr. Twenty-four-hour savings, however, were not observed until 19 days of age. Simple PAR performance deficits following scopolamine injection were first seen at 15 days of age. Mice in those age groups exhibiting 24-hr retention (19-day-olds and adults) were used to assess carry-over effects of scopolamine on retest. Only in the case of juveniles did scopolamine, injected prior to training, disrupt 24-hr retest performance. Since methylscopolamine, a peripherally active anticholinergic, had no effect on activity and PAR performance, it is assumed that scopolamine's effects were of central origin. The results suggest that behavioral suppression comes under cholinergic control during the second and third postnatal weeks but that cholinergic mechanisms may not mediate response inhibition uniformly throughout development.