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The hippocampus supports a multiplicity of functions, with the dorsal region contributing to spatial representations and memory, and the ventral hippocampus (vH) being primarily involved in emotional processing. While spatial encoding has been extensively investigated, how the vH activity is tuned to emotional states, e.g. to different anxiety levels, is not well understood. We developed an adjustable linear track maze (aLTM) for male mice with which we could induce a scaling of behavioral anxiety levels within the same spatial environment. Using in vivo single-unit recordings, optogenetic manipulations and population-level analysis, we examined the changes and causal effects of vH activity at different anxiety levels. We found that anxiogenic experiences activated the vH and that this activity scaled with increasing anxiety levels. We identified two processes that contributed to this scaling of anxiety-related activity: increased tuning and successive remapping of neurons to the anxiogenic compartment. Moreover, optogenetic inhibition of the vH reduced anxiety across different levels, while anxiety-related activity scaling could be decoded using a linear classifier. Collectively, our findings position the vH as a critical limbic region that functions as an 'anxiometer' by scaling its activity based on perceived anxiety levels. Our discoveries go beyond the traditional theory of cognitive maps in the hippocampus underlying spatial navigation and memory, by identifying hippocampal mechanisms selectively regulating anxiety. Significant statement This study reveals how the ventral hippocampus (vH) functions as an "anxiometer", tuning its activity to different anxiety levels. Using an adjustable linear track maze (aLTM) for mice, we demonstrated that vH activity scales with increased anxiety. By recording single-neuron activity and performing optogenetic manipulation of vH during the aLTM task, we identified key neuronal mechanisms for neuronal scaling during anxiety. Additionally, a linear classifier was used to highlight anxiety-related activity scaling. Our findings advance the understanding of hippocampal function beyond spatial navigation and memory, offering new insights into how the brain regulates anxiety at the neuronal level., (Copyright © 2025 the authors.)

Acquiring and exploiting memories of rewarding experiences is critical for survival. The spatial environment in which a rewarding stimulus is encountered regulates memory retrieval. The ventral hippocampus (vH) has been implicated in contextual memories involving rewarding stimuli such as food, social cues or drugs. Yet, the neuronal representations and circuits underlying contextual memories of socially rewarding stimuli are poorly understood. Here, using in vivo electrophysiological recordings, in vivo one-photon calcium imaging, and optogenetics during a social reward contextual conditioning paradigm in male mice, we show that vH neurons discriminate between contexts with neutral or acquired social reward value. The formation of context-discriminating vH neurons following learning was contingent upon the presence of unconditioned stimuli. Moreover, vH neurons showed distinct contextual representations during the retrieval of social reward compared to fear contextual memories. Finally, optogenetic inhibition of locus coeruleus (LC) projections in the vH selectively disrupted social reward contextual memory by impairing vH contextual representations. Collectively, our findings reveal that the vH integrates contextual and social reward information, with memory encoding of these representations supported by input from the LC., (© 2024. The Author(s).)

The present case report describes a rare case of a cardiac abnormality diagnosed as Supravalvular Mitral Stenosis in an asymptomatic cat. An 11-years old cat was presented for orthopedic evaluation, and during general clinical examination a heart rate of 180 bpm and left diastolic cardiac murmur grade III-IV/VI, between the mitral and aortic foci, were found. Radiographic, echocardiographic, angiocardiographic and post-mortem (the patient died during anesthesia performed to diagnose the orthopedic condition) magnetic resonance and pathologic findings are reported herein., (© 2022. Società Italiana di Ultrasonologia in Medicina e Biologia (SIUMB).)