The brain's response to sensory input is strikingly modulated by behavioral state. Notably, the visual response of mouse primary visual cortex (V1) is enhanced by locomotion, a tractable and accessible example of a time-locked change in cortical state. The neural circuits that transmit behavioral state to sensory cortex to produce this modulation are unknown. In vivo calcium imaging of behaving animals revealed that locomotion activates vasoactive intestinal peptide (VIP)-positive neurons in mouse V1 independent of visual stimulation and largely through nicotinic inputs from basal forebrain. Optogenetic activation of VIP neurons increased V1 visual responses in stationary awake mice, artificially mimicking the effect of locomotion, and photolytic damage of VIP neurons abolished the enhancement of V1 responses by locomotion. These findings establish a cortical circuit for the enhancement of visual response by locomotion and provide a potential common circuit for the modulation of sensory processing by behavioral state.

Transmission from striatal cholinergic interneurons (CINs) controls dopamine release through nicotinic acetylcholine receptors (nAChRs) on dopaminergic axons. Anatomical studies suggest that cholinergic terminals signal predominantly through non-synaptic volume transmission. However, the influence of cholinergic transmission on electrical signaling in axons remains unclear. We examined axo-axonal transmission from CINs onto dopaminergic axons using perforated-patch recordings, which revealed rapid spontaneous EPSPs with properties characteristic of fast synapses. Pharmacology showed that axonal EPSPs (axEPSPs) were mediated primarily by high-affinity α6-containing receptors. Remarkably, axEPSPs triggered spontaneous action potentials, suggesting that these axons perform integration to convert synaptic input into spiking, a function associated with somatodendritic compartments. We investigated the cross-species validity of cholinergic axo-axonal transmission by recording dopaminergic axons in macaque putamen and found similar axEPSPs. Thus, we reveal that synaptic-like neurotransmission underlies cholinergic signaling onto dopaminergic axons, supporting the idea that striatal dopamine release can occur independently of somatic firing to provide distinct signaling.

Goal-directed behaviors involve distributed brain networks. The small size of the mouse brain makes it amenable to manipulations of neural activity dispersed across brain areas, but existing optogenetic methods serially test a few brain regions at a time, which slows comprehensive mapping of distributed networks. Laborious operant conditioning training required for most experimental paradigms exacerbates this bottleneck. We present an autonomous workflow to survey the involvement of brain regions at scale during operant behaviors in mice. Naive mice living in a home-cage system learned voluntary head-fixation (>1 hr/day) and performed difficult decision-making tasks, including contingency reversals, for 2 months without human supervision. We incorporated an optogenetic approach to manipulate activity in deep brain regions through intact skull during home-cage behavior. To demonstrate the utility of this approach, we tested dozens of mice in parallel unsupervised optogenetic experiments, revealing multiple regions in cortex, striatum, and superior colliculus involved in tactile decision-making.

Recent advances in the field of Voltage Imaging, with a special focus on new constructs and novel implementations.

Basal Ganglia Advances is a collection highlighting research on the structure, function, and disorders of the basal ganglia. It features studies spanning neuroscience, clinical insights, and computational models, serving as a hub for advances in movement, cognition, and behavior.

Work related to place tuning, spatial navigation, orientation and direction. Mainly includes articles on connectivity in the hippocampus, retrosplenial cortex, and related areas.

This brief review summarizes the most recent progress in in vivo voltage imaging in the neurosciences, as an extension to the work presented at the voltage imaging session of the 2025 FENS regional meeting in Oslo. First, we outline the latest advances in genetically encoded voltage indicators. Next, we examine technical innovations that have reshaped imaging platforms and lay the groundwork to investigate neural activity in real time across large fields of view and in deep tissue. Finally, we highlight a selection of compelling applications that have emerged over the past 5 years, illustrating how voltage imaging evolved from a proof of concept to being deployed to answer pending neuroscientific questions.

Activity of the mesolimbic dopamine system has long been implicated in encoding primary rewards and contributing to the addictive properties of drugs of abuse. Dopamine neurons in the ventral tegmental area (VTA) of the midbrain typically show patterns of spontaneous burst activity that align with the onset of salient events or rewarding stimuli, resulting in phasic dopamine release in the nucleus accumbens (NAc). Fiber photometry is increasingly being used as an accessible technique to quantify neural activity with high temporal resolution at sensors offering signal specificity in stable recordings over extended periods of time. It has been well established by multiple techniques that opioids increase mesolimbic dopamine activity, likely through disinhibition of VTA neurons. Here we used fiber photometry to compare sub-second transient events from VTA neurons with GCaMP6f and dopamine release in the lateral shell of the NAc with dLight1.3b and GRABDA2h in response to morphine treatment. In weekly sessions, one dose of morphine was administered in escalating order (2.5, 5,7.5, and 10 mg/kg, intraperitoneal). Consistent with prior literature, both GCaMP6f in VTA neurons and dLight1.3b in NAc showed patterns of increased signal following morphine treatment. In contrast, morphine suppressed transient activity at GRABDA2h sensors. Further analyses of whole signal streams from each sensor showed a generalized increase, but reduction in variability of the GRABDA2h signal, consistent with the interpretation of sensor saturation. Such results emphasize the importance of the inclusion of appropriate controls to contextualize the interpretation of biosensor responses, particularly in response to pharmacological treatment.

Intracranial atherosclerotic stenosis-related large vessel occlusion (ICAS-LVO) represents a distinct subset of acute ischemic stroke with unique diagnostic and therapeutic challenges during endovascular therapy. Compared with embolic LVO, ICAS-LVO is associated with higher rates of reocclusion and the frequent use of adjunctive interventions. This Brief Practice Update summarizes current evidence and expert consensus to guide the identification and management of ICAS-LVO during endovascular therapy. The Society of Vascular and Interventional Neurology Guidelines and Practice Standards committee convened a multidisciplinary writing group of neurointerventionalists to review available literature and define key clinical questions on ICAS-LVO and endovascular therapy. Evidence was appraised using the Society of Vascular and Interventional Neurology framework for Class of Recommendation and Level of Evidence, adapted from the American College of Cardiology/American Heart Association. Draft statements were iteratively refined and approved by the Society of Vascular and Interventional Neurology Guidelines and Practice Standards Quality Committee for adherence to internal standards and endorsed by the Society of Vascular and Interventional Neurology Board of Directors. Evidence was derived from randomized trials, multicenter registries, cohort studies, post hoc analyses, and meta-analyses addressing diagnostic features, first-line thrombectomy strategies, and adjunctive therapies in ICAS-LVO. Both stent retriever and direct aspiration approaches are acceptable initial strategies; however, durable recanalization is only achieved in about half of patients. Adjunctive use of intravenous or intra-arterial glycoprotein IIb/IIIa inhibitors, balloon angioplasty, and rescue stenting has demonstrated improved recanalization rates and favorable functional outcomes in observational studies, without increased hemorrhagic complications. However, the quality of evidence remains weak. A summary of recommendations is provided to guide practice in common procedural scenarios. This Brief Practice Update provides evidence-based and expert consensus recommendations for the diagnosis and endovascular treatment of ICAS-LVO. Management should be individualized by incorporating the clinical presentation, imaging characteristics, and operator expertise. While adjunctive therapy may be beneficial in select cases, high-quality randomized trials are needed to define optimal strategies and establish standardized algorithms for this challenging stroke subtype.