Keywords 29Lateral habenula, defensive behaviors, single cell calcium imaging in vivo, 30 aversion. Abstract 51Optimal selection of threat-driven defensive behaviors is paramount to an 52 animal's survival. The lateral habenula (LHb) is a key neuronal hub 53 coordinating behavioral responses to aversive stimuli. Yet, how individual LHb 54 neurons represent defensive behaviors in response to threats remains 55 unknown. Here we show that, in mice, a visual threat promotes distinct 56 defensive behaviors, namely runaway (escape) and action-locking (immobile-57 like). Fiber photometry of bulk LHb neuronal activity in behaving animals 58 revealed an increase and decrease of calcium signal time-locked with 59 runaway and action-locking, respectively. Imaging single-cell calcium 60 dynamics across distinct threat-driven behaviors identified independently 61 active LHb neuronal clusters. These clusters participate during specific time 62 epochs of defensive behaviors. Decoding analysis of this neuronal activity 63 unveiled that some LHb clusters either predict the upcoming selection of the 64 defensive action or represent the selected action. Thus, heterogeneous 65 neuronal clusters in LHb predict or reflect the selection of distinct threat-driven 66 defensive behaviors. 67 68 69 70 71 72 73 74When facing an external threat, animals select from a repertoire of innate 75 behavioral responses ranging from escape (runaway) to immobile-like (action-76 locking) strategies (Evans et al., 2019). These behaviors ultimately increase 77 individual survival, rely on the external environment, and can be adopted by 78 the same animal (De Franceschi et al., 2016; Eilam, 2005). The detection of a 79threat and the optimal selection of such threat-driven actions (i.e. runaway or 80 action-locking) require the coordination of complex brain networks. The recent 81 analysis of threat-driven escape behaviors unraveled the essential 82 contribution of neuronal circuits including the amygdala, the superior 83
Making decisions that factor the cost of time is fundamental to survival. Yet, while it is readily appreciated that our perception of time is intimately involved in this process, theories regarding intertemporal decision-making and theories regarding time perception are treated, largely, independently. Even within these respective domains, models providing good fits to data fail to provide insight as to why, from a normative sense, those fits should take their apparent form. Conversely, normative models that proffer a rationalization for why an agent should weigh options in a particular way, or to perceive time in a particular way, fail to account for the full body of well-established experimental evidence. Here we review select, yet key advances in our understanding, identifying conceptual breakthroughs in the fields of intertemporal decision-making and in time perception, as well as their limits and failings in the face of hard-won experimental observation. On this background of accrued knowledge, a new conception unifying the domains of decision-making and time perception is put forward (Training-Integrated Maximization of Reinforcement Rate, TIMERR) to provide a better fit to observations and a more parsimonious reckoning of why we make choices, and thereby perceive time, the way we do.
Motivational states are complex and consist of cognitive, emotional, and physiological components controlled by a network across multiple brain regions. An integral component of this neural circuitry is the bed nucleus of the stria terminalis (BNST). Here, we identified a subpopulation of neurons within BNST expressing the gene prepronociceptin (Pnoc BNST ), that can modulate the rapid changes in physiological arousal that occur upon exposure to stimuli with motivational salience. Using in vivo two-photon calcium imaging we found that excitatory responses from individual Pnoc BNST neurons directly corresponded with rapid increases in pupillary size and occurred upon exposure to both aversive and rewarding odors. Furthermore, optogenetic activation of these neurons increased pupillary size, but did not alter approach/avoidance or locomotor behaviors. These findings suggest that excitatory responses in Pnoc BNST neurons encode rapid arousal responses irrespective of tested behaviors. Further histological, electrophysiological, and single-cell RNA sequencing data revealed that Pnoc BNST neurons are composed of genetically and anatomically identifiable subpopulations that can be further investigated. Taken together, our findings demonstrate a key role for a Pnoc BNST neuronal ensemble in encoding the rapid arousal responses that are triggered by motivational stimuli.
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