Enhanced right amygdala activity in adolescents during encoding of positively valenced pictures

Abstract

While studies among adults implicate the amygdala and interconnecting brain regions in encoding emotional stimuli, few studies have examined whether developmental changes occur within this emotional-memory network during adolescence. The present study examined whether adolescents and adults differentially engaged the amygdala and hippocampus during successful encoding of emotional pictures, with either positive or negative valence. Eighteen adults and twelve adolescents underwent event-related fMRI while encoding emotional pictures. Approximately 30 minutes later, outside the scanner, subjects were asked to recall the pictures seen during the scan. Age group differences in brain activity in the amygdala and hippocampus during encoding of the pictures that were later successfully and unsuccessfully recalled were separately compared for the positive and negative pictures. Adolescents, relative to adults, demonstrated enhanced activity in the right amygdala during encoding of positive pictures that were later recalled compared to not recalled. There were no age group differences in amygdala or hippocampal activity during successful encoding of negative pictures. The findings of preferential activity within the adolescent right amygdala during successful encoding of positive pictures may have implications for the increased reward and novelty seeking behavior, as well as elevated rates of psychopathology, observed during this distinct developmental period.

Use of the light/dark test for anxiety in adult and adolescent male rats

“…Adolescent rats also have a deficit in expression of conditioned fear despite being able to retain the fear memory and express a normal freezing reaction in adulthood [71]. These data are consistent with the hypothesis that a combination of hyperactive approach and hypoactive avoidance contribute to the peak in risk taking and novelty seeking behavior during adolescence [13,14,72,73]. …”

“…Risk taking behavior peaks during adolescence and contributes to most of the major causes of adolescent injury and mortality [11,12]. Immature function of corticolimbic and neuromodulatory systems mediating avoidance of aversive stimuli is thought to contribute to these changes in adolescent behavior [13,14]. Behavior in unconditioned anxiety tests such as the LD test is thought to reflect impulsivity or risk taking in addition to anxiety, so the LD test may be a useful model to investigate neural systems relevant to adolescent risk taking [15–17].…”

Typical and Atypical Neurodevelopment for Face Specialization: An fMRI Study

“…The importance of the amygdala in face processing is well documented but findings are mixed as to whether children and adolescents show less (Ebner et al 2013), more (Guyer et al 2008; Hoehl et al 2010; Killgore and Yurgelun-Todd 2007; Vasa et al 2011) or comparable (Lobaugh et al 2006) levels of activation to faces than adults. Most of these studies used group comparisons of children and adults rather than examined changes with age over a developmental time window or used correlations with age, as in the present study.…”

Arrested development? Reconsidering dual-systems models of brain function in adolescence and disorders

“…These studies have been largely cross-sectional, and smaller in scope than investigations of developmental changes in brain structure, although the use of longitudinal methods and larger sample sizes has been growing in recent years (reviewed in [29]; see also [30]). Findings relevant to the dual-systems model include multiple reports of heightened subcortical (amygdala or VS) responses in adolescents to affective stimuli, including some emotional expressions and certain phases of reward processing [1-4,31,32]. Other studies contribute demonstrations of diffuse (non-focal) or diminished patterns of activity in PFC during cognitive control tasks, alongside potentially compensatory engagement of additional brain regions to achieve control [5-8,33-35].…”