Lateral septum as a nexus for mood, motivation, and movement

•The lateral septum (LS) is organized along rostral/caudal and dorsal/ventral axes.•The LS computes a context-dependent ‘integrated movement value signal’.•The integrated signal is sent downstream to guide decisions and optimize performance.•Integration failure may result in contextually inappropriate motor responses.•This theory explains contradictions in LS results related to mood and movement. The lateral septum (LS) has been implicated in a wide variety of functions, including emotional, motivational, and spatial behavior, and the LS may regulate interactions between the hippocampus and other regions that mediate goal directed behavior. In this review, we suggest that the lateral septum incorporates movement into the evaluation of environmental context with respect to motivation, anxiety, and reward to output an ‘integrated movement value signal’. Specifically, hippocampally-derived contextual information may be combined with reinforcement or motivational information in the LS to inform task-relevant decisions. We will discuss how movement is represented in the LS and the literature on the LS’s involvement in mood and motivation. We will then connect these results to LS movement-related literature and hypotheses about the role of the lateral septum. We suggest that the LS may communicate a movement-scaled reward signal via changes in place-, movement-, and reward-related firing, and that the LS should be considered a fundamental node of affect and locomotor pathways in the brain.