The canary in the coalmine: The sensitivity of mesolimbic dopamine to environmental adversity during development

Ventral striatal activity links adversity and reward processing in children

“…Early childhood is considered a sensitive period as variations in the quality of experience during this time have lasting implications for behavioral, neurophysiological, and neuroendocrine organization. This may be especially true of the reward system, given its role in learning and motivated behavior specifically, and its importance for adaptation to different environments more generally (for discussion see Gatzke-Kopp 2011;Frankenhuis & Weerth, 2013). For example, using tasks that engaged the reward system, our results show that children who experienced greater adversity exhibited potentiated reward-related learning and impulsive decision-making.…”

“…It is unclear whether mechanisms relating adversity and reward processing are molecular (e.g., D2-receptor down-regulation; Hall et al, 1998), anatomical (e.g., volumetric changes within the reward system or in the integrity of fiber tracts connecting the reward system to other brain regions, etc. ), or involve interactions with other systems such as the stress system (see Gatzke-Kopp, 2011;Piazza, Maccari, Deminiére, Le Moal, Morméde, & Simon 1991;Piazza & Le Moal, 1996;Pruessner et al, 2004). These …”

“…According to developmental and evolutionary theory (Gatzke-Kopp; Gluckman & Hanson, 2004;Meaney, 2001;Meaney, 2010), biological systems, such as the reward system, enjoy considerable functional plasticity early in development, making them highly attuned to indicators of environmental quality. Thus, adjustments in dopamine-related phenotypic traits -including dopamine availability, dopamine receptor density, and dopamine-mediated behavioral traits such as learning rate to rewards, activity level, and novelty seeking -can occur in response to variation in environmental quality, including variation that falls within a normative range (Gatzke-Kopp, 2011;Gluckman & Hanson, 2004). These adjustments may be adaptive in the short-term, but carry the burden of increased risk of adverse outcomes such as addiction and psychopathology.…”

“…These effects appear to extend to humans, as early-life adversity has been associated with elevated levels of striatal dopamine (Egerton et al, 2016;Preussner et al, 2004), and increased striatal dopamine release to rewarding stimuli such as amphetamine (Oswald et al, 2014). Whether these associations hold for normative levels of adversity -as might be predicted (Gatzke-Kopp, 2011;Gluckman & Hanson, 2004) -is unknown.…”

Striatal dopamine receptor plasticity in neurotensin deficient mice

“…The mesolimbic and nigrostriatal DA systems are known to display a great deal of plasticity in response to pharmacological [30–32], genetic [33,34], and developmental manipulations [35]. The experiments described in this paper examined whether a deficit in NT produced alterations in DA system tone and function by investigating striatal and cortical DA and DA metabolite concentrations, DA receptor and transporter gene expression and binding, and behavioral sensitivity to selective DA receptor agonists in NT −/− mice.…”