“…Study design might play a role, since studies reporting increased NAcc activity during reward in individuals with bipolar disorder tended to use card guessing or roulette tasks (Caseras et al, 2013; Mason et al, 2014; Nusslock et al, 2014), whereas studies reporting decreased NAcc activity tended to use Monetary Incentive Delay (or MID) tasks (O'Sullivan et al, 2011; Schreiter et al, 2016). Other methodological reasons for variation might include smaller sample sizes (e.g., fewer than 20 per group (Abler et al, 2008; Berghorst et al, 2016; Bermpohl et al, 2010; Kollmann et al, 2017; Linke et al, 2012; Mason et al, 2014; Nusslock et al, 2012; O'Sullivan et al, 2011; Schreiter et al, 2016; Singh et al, 2013; Trost et al, 2014; Urošević et al, 2016; Yip et al, 2015)), insufficiently large incentives to increase NAcc activity in healthy controls (Nusslock et al, 2012), or the lack of neutral or loss conditions for comparison (Nusslock et al, 2012). Thus, while some FMRI evidence implies abnormalities in the neural processing of incentives in bipolar disorder, the direction and strength of these effects remains unclear.…”