| First Author | Kosugi K | Year | 2021 |
| Journal | Hippocampus | Volume | 31 |
| Issue | 3 | Pages | 294-304 |
| PubMed ID | 33296119 | Mgi Jnum | J:347171 |
| Mgi Id | MGI:7616600 | Doi | 10.1002/hipo.23289 |
| Citation | Kosugi K, et al. (2021) Activation of ventral CA1 hippocampal neurons projecting to the lateral septum during feeding. Hippocampus 31(3):294-304 |
| abstractText | A number of studies have reported the involvement of the ventral hippocampus (vHip) and the lateral septum (LS) in negative emotional responses. Besides these well-documented functions, they are also thought to control feeding behavior. In particular, optogenetic and pharmacogenetic interventions to LS-projecting vHip neurons have demonstrated that the vHip(-->LS) neural circuit exerts an inhibition on feeding behavior. However, there have been no reports of vHip neuronal activity during feeding. Here, we focused on LS-projecting vCA1 neurons (vCA1(-->LS) ) and monitored their activity during feeding behaviors in mice. vCA1(-->LS) neurons were retrogradely labeled with adeno-associated virus carrying a ratiometric Ca(2+) indicator and measured compound Ca(2+) dynamics by fiber photometry. We first examined vCA1(-->LS) activity in random food-exploring behavior and found that vCA1(-->LS) activation seemed to coincide with food intake; however, our ability to visually confirm this during freely moving behaviors was not sufficiently reliable. We next examined vCA1(-->LS) activity in a goal-directed, food-seeking lever-press task which temporally divided the mouse state into preparatory, effort, and consummatory phases. We observed vCA1(-->LS) activation in the postprandial period during the consummatory phase. Such timing- and pathway-specific activation was not observed from pan-vCA1 neurons. In contrast, reward omission eliminated this activity, indicating that vCA1(-->LS) activation is contingent on the food reward. Sated mice pressed the lever significantly fewer times but still ate food; however, vCA1(-->LS) neurons were not activated, suggesting that vCA1(-->LS) neurons did not respond to habitual behavior. Combined, these results suggest that gastrointestinal interoception rather than food-intake motions or external sensations are likely to coincide with vCA1(-->LS) activity. Accordingly, we propose that vCA1(-->LS) neurons discriminate between matched or unmatched predictive bodily states in which incoming food will satisfy an appetite. We also demonstrate that vCA1(-->LS) neurons are activated in aversive/anxious situations in an elevated plus maze and tail suspension test. Future behavioral tests utilizing anxious conflict and food intake may reconcile the multiple functions of vCA1(-->LS) neurons. |
