Biology subjects

Ishii, K. K.

Publications and source records attributed to Ishii, K. K..

5 recordsLinked to original sources

bioRxiv2026

A cholinergic eligibility trace facilitates amygdala plasticity in flavour avoidance learning

When an animal consumes a new food and consequently feels ill, it rapidly and robustly learns to avoid this food in the future, a form of learning termed conditioned flavour avoidance (CFA). Postingestive malaise often occurs long after novel food consumption, necessitating a neural mechanism that can facilitate plasticity between temporally distant events. Neuromodulators, acting through G-protein-coupled receptors (GPCRs) that can influence neuronal excitability on extended timescales, may facilitate this process. The projection of parabrachial (PB) Calca neurons to the central amygdala (CeA) is critical for formation of CFA. Here, we demonstrate that these neurons overlap with a PB population that releases acetylcholine (ACh) in the CeA. ACh is released in CeA during consumption of a novel solution and subsequent visceral malaise, consistent with a role in CFA acquisition. Two-photon calcium imaging in brain slices reveals that ACh widely activates CeA neurons and enhances glutamatergic responsivity on a timescale consistent with CFA learning. CRISPR-Cas9-mediated genetic knockdown and optogenetics demonstrate that ACh from PB facilitates CFA behavior. Large-scale neuronal recordings in the CeA along with our CRISPR approach reveal that loss of ACh signaling to CeA blocks key signatures of CFA-associated plasticity. Together, these data point to the cholinergic input from PB to central amygdala as a critical neuromodulatory signal that links activity over long timespans to facilitate associative learning in CFA.

neuroscience↗

bioRxiv2026

Subcortical recruitment dissociates isoflurane emergence from distinct wakeful states in mice

Emergence from general anesthesia, defined by a recovery of consciousness to the wakeful state, is a clinically consequential state transition that remains a passive process dependent on drug clearance. Despite the critical use of anesthesia, the neural circuitry underlying behavioral recovery remains poorly defined. Here, we map whole-brain neural activity during emergence from isoflurane anesthesia in mice using Fos immunolabeling, tissue clearing, and light-sheet microscopy. This approach enables unbiased quantification of neural activity at cellular resolution across the intact whole brain and supports subsequent network analysis. Rather than resembling wakefulness, emergence exhibits widespread cortical suppression alongside selective activation of discrete subcortical nuclei. This pattern of activity includes both previously implicated arousal-related regions and lesser-studied structures linked to respiratory, autonomic, interoceptive, and cerebellar function. By comparing emergence to two behaviorally distinct wakeful control states, we find that control state selection substantially shapes interpretation of whole-brain activity maps. This establishes dual-state comparisons as a broadly useful strategy for state-dependent circuit mapping. Functional network analysis further elucidates candidate central regions that strongly covary together during emergence, with the most integrated region being the ventral orbital cortex. This approach allows for targeted causal investigation, linking brain-wide circuit discovery with future hypothesis-driven mechanistic interrogation. Together, we find that emergence from isoflurane anesthesia reflects selective subcortical recruitment rather than broad global reactivation toward wakefulness. Significance StatementMillions of people undergo general anesthesia each year. While anesthetic unconsciousness is induced rapidly, emergence from altered consciousness is unpredictable. Neural mechanisms that underlie behavioral emergence remain poorly defined. Using whole-brain Fos mapping at cellular resolution, we found that emergence from isoflurane anesthesia is characterized by widespread cortical suppression alongside selective activation of discrete subcortical, autonomic, hindbrain, and cerebellar nuclei. This selective systems-level activity pattern identifies behavioral emergence as more than a simple global return toward wakefulness and highlights underappreciated neural circuitry involved in post-anesthetic recovery. Network analysis of the Fos maps further identifies candidate regions for targeted causal investigation of emergence-related regions.

neuroscience↗

bioRxiv2025

Hierarchical and Spatial Mapping of Whole-Brain c-Fos Activity Reveals Distinct Opioid and Withdrawal Neuronal Ensembles

How opioid exposure and withdrawal states shape brain activity at the systems and circuit level remains poorly understood. Here, we use whole-brain, cellular-resolution c-Fos mapping to define brain-wide activity patterns and neuronal ensembles associated with morphine administration and withdrawal. To account for the brains anatomically nested structure, we developed and applied a hierarchical statistical framework that detects region-specific changes in activity and outperforms conventional methods that treat brain regions as individual, unrelated units. These distributed signals formed ensembles with consistent and anatomically structured patterns of activity, both within subregions and across multiple connected brain areas. By combining TRAP2-based activity tagging with acute whole-brain c-Fos staining, we identified morphine- and withdrawal-activated ensembles and found that they are largely non-overlapping at the single-cell level, even within the same brain region. Integration with existing spatial transcriptomics datasets identified molecular markers for these state-specific ensembles in key brain areas such as the nucleus of accumbens, amygdala and ventral tegmental areas. Lastly, by integrating Allen mouse whole-brain transcriptional datasets, we identified the molecular identity of the morphine- administration and withdrawal ensembles. These findings define dissociable neuronal ensembles that encode opposing drug states and introduce a scalable framework for linking whole-brain activity to molecular and circuit-level mechanisms. HighlightsO_LIWhole-brain neural activity mapping identifies the regional and spatial difference of morphine-administration and withdrawal neuronal ensembles. C_LIO_LIBRANCH, a hierarchical statistical testing framework, offers increased sensitivity and anatomical interpretability for whole-brain datasets. C_LIO_LITRAP2-based activity tagging reveals brain-wide separation of acute morphine and withdrawal ensembles at the cellular level. C_LIO_LIA systematic analysis of the whole brain neural activity data combined with spatial transcriptomic data revealed molecular features of opioid-related neural ensembles. C_LI

neuroscience↗

bioRxiv2025

Esr1-Dependent Signaling and Transcriptional Maturation in the Medial Preoptic Area of the Hypothalamus Shapes the Development of Mating Behavior during Adolescence

Mating and other behaviors emerge during adolescence through the coordinated actions of steroid hormone signaling throughout the nervous system and periphery. In this study, we investigated the transcriptional dynamics of the medial preoptic area (MPOA), a critical region for reproductive behavior, using single-cell RNA sequencing (scRNAseq) and in situ hybridization techniques in male and female mice throughout adolescence development. Our findings reveal that estrogen receptor 1 (Esr1) plays a pivotal role in the transcriptional maturation of GABAergic neurons within the MPOA during adolescence. Deletion of the estrogen receptor gene, Esr1, in GABAergic neurons (Vgat+) disrupted the developmental progression of mating behaviors in both sexes, while its deletion in glutamatergic neurons (Vglut2+) had no observable effect. In males and females, these neurons displayed distinct transcriptional trajectories, with hormone-dependent gene expression patterns emerging throughout adolescence and regulated by Esr1. Esr1 deletion in MPOA GABAergic neurons, prior to adolescence, arrested adolescent transcriptional progression of these cells and uncovered sex-specific gene-regulatory networks associated with Esr1 signaling. Our results underscore the critical role of Esr1 in orchestrating sex-specific transcriptional dynamics during adolescence, revealing gene regulatory networks implicated in the development of hypothalamic controlled reproductive behaviors. One Sentence SummarySingle cell RNA sequencing reveals how adolescent sex hormones sculpt hypothalamic cell types required for mating behavior.

neuroscience↗

bioRxiv2023

Post-Mating Inhibition of Female Sexual Drive via Heterogeneous Neuronal Ensembles in the Medial Preoptic Area

Male ejaculation acutely suppresses sexual motivation in male mice. In contrast, relatively little is known about how male ejaculation affects sexual motivation and sexual behavior in female mice. How the brain responds to completion of mating is also unclear. Here, by using self-paced mating assay, we first demonstrate that female mice show decreased sexual motivation acutely after experiencing male ejaculation. By using brain-wide analysis of activity-dependent labeling, we next pinpointed the medial preoptic area as a brain region strongly activated during the post-ejaculatory period. Furthermore, using freely moving in vivo calcium imaging to compare neural activity of inhibitory and excitatory neurons in the medial preoptic area, we revealed that a subset of the neurons in this region respond significantly and specifically to male ejaculation but not to female-to-male sniffing or to male mounting. While there were excitatory and inhibitory neurons that showed increased response to male ejaculation, the response magnitude as well as the proportion of neurons responding to the event was significantly larger in the inhibitory neuron population. Next, by unbiased classification of their responses, we also found a subpopulation of neurons that increase their activity late after the onset of male ejaculation. These neurons were all inhibitory indicating that male ejaculation induces a prolonged inhibitory activity in the medial preoptic area. Lastly, we found that chemogenetic activation of medial preoptic area neurons that were active during post-ejaculatory period, but not during appetitive or consummatory periods, were sufficient to suppress female sexual motivation. Together, our data illuminate the importance of medial preoptic area as a brain node which encodes a negative signal that sustains low sexual motivation state after the female mice experience ejaculation. HighlightsO_LIFemale mice show decreased sexual motivation in the post-ejaculatory period. C_LIO_LIA subset of MPOA neurons in female respond specifically to male ejaculation. C_LIO_LIMale-ejaculation evokes persistent activity in MPOA inhibitory neurons in females. C_LIO_LIActivation of a subset of MPOA neurons is sufficient to suppress female sexual motivation. C_LI

neuroscience↗