The ventral pallidum (VP) is critical for invigorating reward seeking and is also involved in punishment avoidance, but how it contributes to such opposing behavioural actions remains unclear. Here we show that GABAergic and glutamatergic VP neurons selectively control behaviour in opposing motivational contexts. In vivo recording combined with optogenetics in mice revealed that these two populations oppositely encode positive and negative motivational value, are differentially modulated by animal's internal state and determine the behavioural response during motivational conflict. Furthermore, GABAergic VP neurons are essential for movements towards reward in a positive motivational context, but suppress movements in an aversive context. In contrast, glutamatergic VP neurons are essential for movements to avoid a threat but suppress movements in an appetitive context. Our results indicate that GABAergic and glutamatergic VP neurons encode the drive for approach and avoidance, respectively, with the balance between their activities determining the type of motivational behaviour.

Witnessing another person’s suffering elicits vicarious brain activity in areas that are active when we ourselves are in pain. Whether this activity influences prosocial behavior remains the subject of debate. Here participants witnessed a confederate express pain through a reaction of the swatted hand or through a facial expression, and could decide to reduce that pain by donating money. Participants donate more money on trials in which the confederate expressed more pain. Electroencephalography shows that activity of the somatosensory cortex I (SI) hand region explains variance in donation. Transcranial magnetic stimulation (TMS) shows that altering this activity interferes with the pain–donation coupling only when pain is expressed by the hand. High-definition transcranial direct current stimulation (HD-tDCS) shows that altering SI activity also interferes with pain perception. These experiments show that vicarious somatosensory activations contribute to prosocial decision-making and suggest that they do so by helping to transform observed reactions of affected body-parts into accurate perceptions of pain that are necessary for decision-making.

No abstract

26The ventral pallidum (VP) is critical for invigorating reward seeking and is also involved in 27 punishment avoidance, but how it contributes to such opposing behavioural actions remains 28 unclear. Here we show that GABAergic and glutamatergic VP neurons selectively control 29 behaviour in opposing motivational contexts. In vivo recording combined with optogenetics in 30 mice revealed that these two populations oppositely encode positive and negative motivational 31 value, are differentially modulated by animal's internal state and determine the behavioural 32 response during motivational conflict. Furthermore, GABAergic VP neurons are essential for 33 movements towards reward in a positive motivational context, but suppress movements in an 34 aversive context. In contrast, glutamatergic VP neurons are essential for movements to avoid a 35 threat but suppress movements in an appetitive context. Our results indicate that GABAergic and 36 glutamatergic VP neurons encode the drive for approach and avoidance, respectively, with the 37 balance between their activities determining the type of motivational behaviour. 38 39 and transmits information to multiple brain regions involved in motor control and motivation, such 49 as the ventral tegmental area (VTA), lateral habenula (LHb), mediodorsal thalamus and 50 pedunculopontine tegmental nucleus (Haber and Knutson, 2010). This connectivity places the VP 51 in an ideal location to transform information about the expected value of stimuli into motivation 52 (Mogenson et al., 1980). Indeed, a large body of work, comprehensively reviewed by others 53 (Humphries and Prescott, 2010;Root et al., 2015;Smith et al., 2009;Stephenson-Jones, 2019), 54 has identified the VP as a crucial driver of reward-seeking behaviour. For example, the VP is 55 important for the normal hedonic reactions to sucrose (Farrar et al., 2008), and lesions to the VP 56 decrease an animal's willingness to work for reward (Farrar et al., 2008;Richard et al., 2016). 57Conversely, rats will work to electrically self-stimulate their VP (Panagis et al., 1995; Panagis et 58 al., 1997), and pharmacological activation and disinhibition of the VP can both trigger feeding in 59 sated animals (Stratford et al., 1999). 60 61The VP is also implicated in avoidance behaviours (Stephenson-Jones, 2019;Wulff et al., 2018), 62as intra-VP mu-opioid activity is sufficient to drive conditioned place aversion (Skoubis and 63 Maidment, 2003), and activating mu opioid receptors in the VP can impair conditioned taste 64 avoidance (Inui and Shimura, 2017). In a similar manner, disinhibiting the VP through injections 65 of the GABAergic antagonist bicuculline induces anxiety-related behaviours and increases 66 avoidance in an approach/avoidance task in primates (Saga et al., 2017;Smith and Berridge, 2005). 67These findings suggest that the VP plays a role in the motivation to both seek reward and avoid 68 punishment. 69 70While the VP appears critical for motivating behaviour in appetitive and aversive contexts, how 71 this ...