Conflict between Threat Sensitivity and Sensation Seeking in the Adolescent Brain: Role of the Hippocampus, and Neurobehavioural Plasticity Induced by Pleasurable Early Enriched Experience.

Alberto Fernández-Teruel

doi:10.3390/brainsci11020268

Abstract

Adolescence is characterized both by the exacerbation of the experience of anxiety, fear or threat, on one hand, and by increased reward seeking (reward sensitivity) and risk taking on the other hand. The rise of these apparently opposite processes, i.e., threat-related anxiety and reward-related sensation seeking, seems to stem from a relatively decreased top-down inhibition of amygdala and striatal circuits by regulatory systems (e.g., prefrontal cortex, hippocampus) that mature later. The present commentary article aims to discuss recent related literature and focusses on two main issues: (i) the septo-hippocampal system (in particular the ventral hippocampus) might be a crucial region for the regulation of approach–avoidance conflict and also for the selection of the most appropriate responses during adolescence, and (ii) developmental studies involving early-life pleasurable-enriched experience (as opposed to early-life adversity) might be a useful study paradigm in order to decipher whether neuroplasticity induced by such experiences (for example, in the hippocampus and associated circuitry) may lead to better top-down inhibition and more “balanced” adolescent responses to environmental demands.

Highlights

Adolescence is a period of development characterized by an exacerbation of the experience of anxiety, fear or threat, on one hand, as well as—paradoxically—by increased reward seeking and risk taking [1,2,3,4,5,6,7]
It is a developmental period characterized by contrasting traits or phenotypes, such as increases in anxiety symptomatology, behaviourally characterized by avoidance, and increased risk taking behaviour, characterized by approach responses [1]
This paradoxical “double-edged sword”—the rise of both anxiety and sensation seeking—of adolescence seems to rely on the particular maturational stages and characteristics of amygdala (AMY)- and striatum-related circuits [1,2,3,4,5]. These threat- and rewardrelated circuits exhibit a developmental stage during adolescence that is often characterized by increased excitability of both, whereas regulatory systems responsible for top-down inhibitory control, such as the prefrontal cortex (PFC) and the hippocampus (HPC; in particular the ventral part, vHPC), seem to mature later (e.g., [8] and references therein; see Section 2.1)

Summary

Introduction

Adolescence is a period of development characterized by an exacerbation of the experience of anxiety, fear or threat, on one hand, as well as—paradoxically—by increased reward seeking (reward sensitivity) and risk taking [1,2,3,4,5,6,7]. These threat- and rewardrelated (respectively) circuits exhibit a developmental stage during adolescence that is often characterized by increased excitability of both, whereas regulatory systems responsible for top-down inhibitory control, such as the prefrontal cortex (PFC) and the hippocampus (HPC; in particular the ventral part, vHPC), seem to mature later (e.g., [8] and references therein; see Section 2.1) These four regions interact (i.e., are interconnected) and influence the behavioural output during adolescence [1,3,4,5,8,9,10,11,12]. It is proposed that the exacerbation of anxiety-/fear- and reward-related (sensation seeking, risk taking, impulsivity) experiences and behaviours is mediated by that decreased top-down inhibitory control [1,3,8,13]

Shifting the Focus to “Threat–Reward” Conflict

Approach–Avoidance Conflict in Adolescence

Conclusions