Fig. 4.

Relationship between substantia nigra/ventral tegmental area (SN/VTA) structural integrity and flexibility of instrumental learning. (A) Higher SN/VTA integrity (indexed by magnetization transfer values of SN/VTA) in older adults correlated with both a reduced action bias and reduced interaction between action and valence learning (n = 42). (B) No correlation between SN/VTA integrity and the action bias or the action–valence interaction in younger adults (n = 30). Scatter plots, in which each dot represents an individual. Abbreviations: GAL, go to avoid losing; GW, go to win; NGAL, no-go to avoid losing; NGW, no-go to win.