Cholinergic interneurons (CINs) are essential elements of striatal circuits and functions. Although acetylcholine signaling via muscarinic receptors (mAChRs) has been well studied, more recent data indicate that postsynaptic nicotinic receptors (nAChRs) located on striatal GABAergic interneurons (GINs) are equally critical. One example is that CIN stimulation induces large disynaptic inhibition of striatal projection neurons (SPNs) mediated by nAChR activation of GINs. Although these circuits are ideally positioned to modulate striatal output, the neurons involved are not definitively identified because of an incomplete mapping of CINs-GINs interconnections. Here, we show that CINs modulate four GINs populations via an intricate mechanism involving co-activation of presynaptic and postsynaptic mAChRs and nAChRs. Using optogenetics, we demonstrate the participation of tyrosine hydroxylase-expressing GINs in the disynaptic inhibition of SPNs via heterotypic electrical coupling with neurogliaform interneurons. Altogether, our results highlight the importance of CINs in regulating GINs microcircuits via complex synaptic/heterosynaptic mechanisms.

Voltage imaging has emerged as a powerful tool for recording membrane potential changes in living cells, offering a direct measurement of rapid neuronal events with high temporal precision. Since the brain is a three-dimensional circuit, it is essential to record signals across a volume. However, achieving effective three-dimensional voltage imaging over large neuronal populations remains challenging due to the need for high imaging speed, high signal-to-noise ratio, and extensive volume coverage. In this study, we demonstrate in vivo three-dimensional voltage imaging in larval zebrafish using oblique plane microscopy and QFDBD-QUAS-driven expression of the genetically encoded voltage indicator Ace-mNeon2-Kv2.1, achieving volumetric imaging rates of up to 200 volumes per second (VPS). This approach enables dye-free voltage imaging, simplifying experimental workflows and improving the reproducibility of in vivo voltage imaging experiments for investigating neuronal circuit dynamics in the living zebrafish animal model.

The neurotransmitter acetylcholine (ACh) is essential in both the central and peripheral nervous systems. Recent studies highlight the significance of interactions between ACh and various neuromodulators in regulating complex behaviors. The ability to simultaneously image ACh and other neuromodulators can provide valuable information regarding the mechanisms underlying these behaviors. Here we developed a series of red fluorescent G-protein-coupled receptor activation-based ACh sensors, with a wide detection range and expanded spectral profile. The high-affinity sensor rACh1h reliably detects ACh release in various brain regions, including the nucleus accumbens, amygdala, hippocampus and cortex. Moreover, rACh1h can be coexpressed with green fluorescent sensors to record ACh release together with other neurochemicals in various behavioral contexts using fiber photometry, mesoscopic imaging and two-photon imaging with high spatiotemporal resolution.

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.

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

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

High-resolution extracellular electrophysiology is the gold standard for recording spikes from distributed neural populations and is especially powerful when combined with optogenetics for manipulation of specific cell types with high temporal resolution. We integrated these approaches into prototype Neuropixels Opto probes, which combine electronic and photonic circuits. These devices pack 960 electrical recording sites and two sets of 14 light emitters onto a 70-μm-wide, 1-cm-long shank, allowing spatially addressable optogenetic stimulation with blue and red light. In mouse cortex, Neuropixels Opto probes delivered high-quality recordings together with spatially addressable optogenetics, differentially activating or silencing neurons at distinct cortical depths. In the mouse striatum and other deep structures, Neuropixels Opto probes delivered efficient optotagging, facilitating the identification of two cell types in parallel. Neuropixels Opto probes represent a promising tool for recording, identifying and manipulating neuronal populations.

Tumors in pet dogs provide a valuable comparative model for evaluating immune checkpoint inhibitor (ICI) therapies in humans. Whether mismatch repair deficiency (MMRd) predicts response to ICI in dogs, as it does in humans, remains unknown. To enable biomarker-driven clinical trials, development of a validated canine mismatch repair (MMR) assay is required. Mass spectrometry identified PMS1 as the binding partner of MLH1 in dogs, rather than PMS2. A novel monoclonal antibody was developed to detect PMS1 in both canine and human tissues by immunohistochemistry (IHC). A multiplex immunofluorescence assay was established to simultaneously detect MLH1, MSH2, MSH6, and PMS2 in parallel to PMS1. MMR protein expression profiles were characterized across 39 human colorectal cancers, 25 patient-derived xenografts (PDXs), and 43 canine tumor samples. PMS1 is frequently lost in conjunction with MLH1 and PMS2 in human colorectal and endometrial tumors. In canine cancers, lymphomas and mast cell tumors demonstrated a high incidence of MMRd typified by the loss of two or more markers, frequently including MLH1/PMS1. Loss of PMS1 alone occurred in three of 19 canine soft tissue sarcomas. A standardized definition of MMRd in dogs is essential to advance biomarker-driven ICI trials. The multiplex MMR assay described here enables detection of MMRd across species and tumor types. MMRd is a frequent event in common canine cancers, establishing dogs as a relevant model for evaluating ICI therapies. These MMR assays are now suitable for implementation in canine biomarker-guided clinical studies.

Anti-CD19 chimeric antigen receptor T (CAR T) cells have promising therapeutic potential for diffuse large B-cell lymphoma (DLBCL), yet many treated patients relapse due to progressive disease driven by CD19-negative clones. Tandem CAR (TCAR) designs co-targeting CD19 and CD20 may overcome this problem. However, murine and primate models do not fully recapitulate human disease and clinical responses to CAR T therapy, limiting preclinical optimization. Moreover, clinical trials are lengthy and costly, further delaying the evaluation of new strategies. By contrast, canine DLBCL closely resembles the human disease, and CAR T trials in canines are feasible, with clinical sequelae that mirror those observed in human CAR T therapy. We previously reported CD20 loss in canine DLBCL patients treated with CD20-specific CAR T cells, consistent with mechanisms of antigen escape in humans. We therefore hypothesized that canine DLBCL could be leveraged to accelerate the translation of more effective TCAR-based strategies, benefiting both canine and human patients. To test this, we first assessed the expression of CD19 and CD20 in canine lymphoma patient samples. We then developed canine TCARs directed against CD19 and CD20 and evaluated their efficacy and specificity against canine DLBCL cells. We show that canine B-cell lymphoma co-expresses CD19 and CD20 with heterogeneous expression patterns similar to those observed in humans, and that TCAR-engineered canine T cells effectively and specifically eliminate cells expressing CD19 and/or CD20. Our TCAR platform holds promise to improve outcomes in canine DLBCL and to further optimize next-generation CAR-based strategies before entering human trials.