Fig. 1. Behavioral circuits characterized by optogenetics.

One of the greatest strengths of optogenetics is the ability to activate distinct subsets of neurons based on biochemical composition or projection target with high temporal resolution. Cell-type-specific targeting has allowed us to establish causal relationships between neural circuit elements and specific behaviors. In addition, the ability to perform projection-specific targeting has allowed us to study functionally-distinct distal projections from individual structures previously thought to be homogeneous in function. These advantages have allowed optogenetics to help build us a more comprehensive neural map of the circuits involved in emotional valence and motivated behaviors: (A) reward, aversion, salience; ((B)–(D)) aversion; (E) reward; (F) aversion; (G) reward, aversion; ((H)–(J)) reward; (K) reward, aversion, movement; (L) aggression; ((M) and (N)) feeding; ((O) and (P)) fear; (Q) anxiety; ((R)–(U)) Fear; (V) Promotes Escape-Related Behavior; (W) Suppresses Escape-Related Behavior. For all figures, structures depicted are not to scale and include a subset of optogenetic behavioral manipulations. Abbreviations: AC, auditory cortex; ARC, arcuate nucleus; BLA, basolateral amygdala; CeA, central amygdala; DG, dentate gyrus; DRN, Dorsal Raphe; EP, entopeduncular nucleus; HPC, hippocampus; LDT, laterodorsal tegmentum; LHb, lateral habenula; mPFC, medial prefrontal cortex; NAc, nucleus accumbens; PVH, paraventricular hypothalamus; RMTg, rostromedial tegmental area; STRd, dorsal striatum; VMHvl, ventrolateral subdivision of the ventromedial hypothalamus; VTA, ventral tegmental area.