Population dynamics underlying associative learning in the dorsal and ventral hippocampus

Abstract

Animals associate cues with outcomes and continually update these associations as new information is presented. The hippocampus is crucial for this, yet how neurons track changes in cue-outcome associations remains unclear. Using 2-photon calcium imaging, we tracked the same dCA1 and vCA1 neurons across days to determine how responses evolve across phases of odor-outcome learning. We find that, initially, odors elicited robust responses in dCA1, whereas in vCA1 responses emerged after learning, including broad representations that stretched across cue, trace, and outcome periods. Population dynamics in both regions rapidly reorganized with learning, then stabilized into ensembles that stored odor representations for days, even after extinction or pairing with a different outcome. Finally, we found stable, robust signals across CA1 when anticipating reward, but not when anticipating inescapable shock. These results identify how the hippocampus encodes, stores, and updates learned associations, and illuminates the unique contributions of dorsal and ventral hippocampus.

Sensory cortical ensembles exhibit differential coupling to ripples in distinct hippocampal subregions

“…Proposed functional variations along the hippocampal longitudinal axis include cognitive versus affective signal processing (Fanselow & Dong, 2010; Moser & Moser, 1998; Strange et al, 2014), fine-grained versus coarse representation of information (Harland et al, 2017; Jung et al, 1994; Poppenk et al, 2013), and faithful versus subjective representation of experienced events (Biane et al, 2022; Yun et al, 2023). Thus, it is likely that dAct and iAct ensembles have different functions.…”

Neural signatures of stress susceptibility and resilience in the amygdala-hippocampal network

“…One week prior to lick training, head bar surgeries were conducted on all mice (8-9 weeks old). Similar to previously described protocol ( 46 ), mice were anesthetized with 1.5% isoflurane with O 2 flow rate of 1 L/min, and head-fixed in a stereotaxic frame. A custom-made titanium head bar was then attached to the skull using Metabond adhesive cement (Parkell, Edgewood, NY).…”

“…For mice that underwent chemogenetic manipulations, adult males (8-9 weeks old) received viral micro-infusion in the same surgery as head bar attachment, similar to previously described protocol ( 46 ). Specifically, AAV8-hSyn-DIO-hM3D(Gq)-mCherry (Addgene, 44361-AAV8, 2.9 x 10 13 vg/ml) or AAV8-hSyn-DIO-mCherry (Addgene, 50459-AAV8, 1.0 x 10 13 vg/ml) was micro-infused in vCA1 bilaterally (500 nL per hemisphere, -3.52 mm AP, ±3.1 ML, -4.2 [150 nL], -4.1 [200 nL] and -4.0 [150 nL] DV, from bregma according to Paxinos and Franklin [2011]), and AAV2retro-CAG-Cre (UNC Vector Core, Ed Boyden’s stock, 4.1x10 12 vg/ml) was micro-infused in BLA bilaterally (500 nL per hemisphere, -1.80 mm AP, ±3.1 ML, -5.0 [150 nL], -4.8 [200 nL] and -4.6 [150 nL] DV).…”

“…Similar to previously described method ( 46 ), a linear support vector machine (SVM) classifier was trained to classify patterns of activity into two discrete categories. Results are reported as the generalized performance of the decoder using cross-validation with 80/20 training/testing split.…”

“…For mice that underwent chemogenetic manipulations, adult males (8-9 weeks old) received viral micro-infusion in the same surgery as head bar attachment, similar to previously described protocol (46). Specifically, AAV8-hSyn-DIO-hM3D(Gq)-mCherry (Addgene, 44361-AAV8, 2.9 x 10 13 vg/ml) or AAV8-hSyn-DIO-mCherry (Addgene, 50459-AAV8, 1.0 x 10…”