Faculty Bibliography

High-density microelectrode arrays have opened new possibilities for systems neuroscience, but brain motion relative to the array poses challenges for downstream analyses. We introduce DREDge (Decentralized Registration of Electrophysiology Data), a robust algorithm for the registration of noisy, nonstationary extracellular electrophysiology recordings. In addition to estimating motion from action potential data, DREDge enables automated, high-temporal-resolution motion tracking in local field potential data. In human intraoperative recordings, DREDge's local field potential-based tracking reliably recovered evoked potentials and single-unit spike sorting. In recordings of deep probe insertions in nonhuman primates, DREDge tracked motion across centimeters of tissue and several brain regions while mapping single-unit electrophysiological features. DREDge reliably improved motion correction in acute mouse recordings, especially in those made with a recent ultrahigh-density probe. Applying DREDge to recordings from chronic implantations in mice yielded stable motion tracking despite changes in neural activity between experimental sessions. These advances enable automated, scalable registration of electrophysiological data across species, probes and drift types, providing a foundation for downstream analyses of these rich datasets.

Cortical networks for the production of spoken language in humans are organized by phonetic features^1,2, such as articulatory parameters^3,4 and vocal pitch^5,6. Previous research has failed to find an equivalent forebrain representation in other species^7-11. To investigate whether this functional organization is unique to humans, here we performed population recordings in the vocal production circuitry of the budgerigar (Melopsittacus undulatus), a small parrot that can generate flexible vocal output^12-15, including mimicked speech sounds¹⁶. Using high-density silicon probes¹⁷, we measured the song-related activity of a forebrain region, the central nucleus of the anterior arcopallium (AAC), which directly projects to brainstem phonatory motor neurons^18-20. We found that AAC neurons form a functional vocal motor map that reflects the spectral properties of ongoing vocalizations. We did not observe this organizing principle in the corresponding forebrain circuitry of the zebra finch, a songbird capable of more limited vocal learning²¹. We further demonstrated that the AAC represents the production of distinct vocal features (for example, harmonic structure and broadband energy). Furthermore, we discovered an orderly representation of vocal pitch at the population level, with single neurons systematically selective for different frequency values. Taken together, we have uncovered a functional representation in a vertebrate brain that displays unprecedented commonalities with speech-related motor cortices in humans. This work therefore establishes the parrot as an important animal model for investigating speech motor control and for developing therapeutic solutions for addressing a range of communication disorders^22,23.

Our brains integrate sensory, cognitive and internal state information with memories to extract behavioral relevance. Cortico-hippocampal interactions likely mediate this interplay, but underlying circuit mechanisms remain elusive. Unlike the entorhinal cortex-to-hippocampus pathway, we know little about the organization and function of the hippocampus-to-cortex feedback circuit. Here we report in mice, two functionally distinct parallel hippocampus-to-entorhinal cortex feedback pathways: the canonical disynaptic route via layer 5 and a novel monosynaptic input to layer 2/3. Circuit mapping reveals that hippocampal input predominantly drives excitation in layer 5 but feed-forward inhibition in layer 2/3. Upon repetitive pairing with cortical layer 1 inputs, hippocampal inputs undergo homosynaptic potentiation in layer 5, but induce heterosynaptic plasticity and spike output in layer 2/3. Behaviorally, hippocampal inputs to layer 5 and layer 2/3 support object memory encoding versus recall, respectively. Two-photon imaging during navigation reveals hippocampal suppression reduces spatially tuned cortical axonal activity. We present a model, where hippocampal feedback could iteratively shape ongoing cortical processing.

To characterise the effectiveness of Bruton tyrosine kinase inhibitors with venetoclax in patients with refractory or relapsed mantle cell lymphoma, with or without the addition of an anti-CD20 antibody. Progression-free and overall survival were estimated for forty-nine patients treated with Bruton tyrosine kinase inhibitors and venetoclax (200 mg, daily) or in combination with an anti-CD20 monoclonal antibody between June 2018 and February 2022 in China. The median number of treatment lines before combination therapy was three (range, 2-7). The median patient age was 62 years, with a male-to-female ratio of 3.08:1. Patients exhibited high-risk features including Ki-67 ≥ 30% (89.8%), blastoid/pleomorphic histology (36.7%), high-risk mantle cell lymphoma International Prognostic Index group (42.9%), complex karyotype (27.7%), TP53 mutations (71.4%), TP53 mutations combined with other high-risk gene mutations including KMT2D, NSD2, CCND1, NOTCH1, CDKN2A, NOTCH2 and SMARCA4 (57.1%), and progression of disease within 24 months (65.3%), with similar efficacy and prognosis to low-risk cases. Basic clinical and cytogenetic characteristics, as well as efficacy and survival, were similar between the dual and triple combination therapy groups (all p > 0.05). The optimal overall response and complete remission rates were 67.4% and 53.1%, respectively. The 3-year progression-free and overall survival rates were 37.5% and 50.8%, respectively. Eastern Cooperative Oncology Group≥2was an independent predictor of progression-free survival. Eastern Cooperative Oncology Group performance status ≥ 2, TP53 mutations combined with other high-risk gene mutationswere independent factors for poor overall survival. The most common adverse reactions were haematological and pulmonary infections. The leading cause of death was disease progression (19/22). The combination of Bruton tyrosine kinase inhibitors and venetoclax, demonstrated good efficacy in patients with refractory or relapsed mantle cell lymphoma, particularly in the early treatment. There was no efficacy or survival advantages of adding CD20 antibodies. Patients in the ultrahigh-risk group required more aggressive treatments.

Astrocytes are a highly abundant glial cell type and perform critical homeostatic functions in the central nervous system. Like neurons, astrocytes have many discrete heterogeneous subtypes. The subtype identity and functions are, at least in part, associated with their anatomical location and can be highly restricted to strategically important anatomical domains. Here, we report that astrocytes forming the glia limitans superficialis, the outermost border of the brain and spinal cord, are a highly specialized astrocyte subtype and can be identified by a single marker: myocilin (Myoc). We show that glia limitans superficialis astrocytes cover the entire brain and spinal cord surface, exhibit an atypical morphology, and are evolutionarily conserved from zebrafish, rodents, and non-human primates to humans. Identification of this highly specialized astrocyte subtype will advance our understanding of CNS homeostasis and potentially be targeted for therapeutic intervention to combat peripheral inflammatory effects on the CNS.

BACKGROUND/UNASSIGNED:handling and arrhythmia susceptibility. METHODS/UNASSIGNED:There are a large number of rare ITPR1 missense variants reported in open data repositories. Based on their locations in the ITPR1 channel structure, we selected and characterized 33 human ITPR1 missense variants from open databases and identified 21 human ITPR1 GOF variants. We generated a mouse model carrying a human ITPR1 GOF variant, ITPR1-W1457G (W1447G in mice). RESULTS/UNASSIGNED:release, delayed afterdepolarization, and triggered activity in Purkinje cells. To assess the potential role of ITPR1 variants in arrhythmia susceptibility in humans, we looked up a gene-based association study in the UK Biobank data set and identified 7 rare ITPR1 missense variants showing potential association with cardiac arrhythmias. Remarkably, in vitro functional characterization revealed that all these 7 ITPR1 variants resulted in GOF. CONCLUSIONS/UNASSIGNED:Our studies in mice and humans reveal that enhanced function of ITPR1, a well-known movement disorder gene, increases the risk for cardiac arrhythmias.

Adipose-derived leptin contributes to energy homeostasis by balancing food intake and motor output, but how leptin acts in brain motor centers remains poorly understood. We investigated the influence of leptin on neuronal activity in two basal ganglia nuclei involved in motor control: the substantia nigra pars compacta (SNc) and pars reticulata (SNr). Using a mouse reporter line to identify cells expressing leptin receptors (LepRs), we found that in both sexes, a majority of SNc dopamine neurons express a high level of LepR. Whole-cell recording in ex vivo midbrain slices from male wild-type mice showed that leptin activates SNc dopamine neurons directly and increases somatodendritic dopamine release. Although LepR expression in SNr GABA output neurons was low, leptin also activated these cells. Additional experiments showed that the influence of leptin on SNr neurons is indirect and involves D1 dopamine receptors and TRPC3 channels. Administration of leptin to male mice increased locomotor activity, consistent with activation of dopamine neurons in the SNc coupled to previously reported amplification of axonal dopamine release by leptin in striatal slices. These findings indicate that in addition to managing energy homeostasis through its actions as a satiety hormone, leptin also promotes axonal and somatodendritic dopamine release that can influence motor output.Significance statement Dopamine neurons regulate motivated behaviors, but how they are influenced by metabolic hormones, like leptin, is incompletely understood. We show here that leptin increases the activity of substantia nigra (SN) pars compacta dopamine neurons directly, and that this enhances somatodendritic dopamine release. Leptin also increases the activity of GABAergic neurons in the SN pars reticulata, but does so indirectly via D1 dopamine receptors activated by locally released dopamine. Consistent with increased nigral dopamine neuron activity and previous evidence showing that leptin amplifies striatal dopamine release, systemic leptin increases locomotor behavior. This increase in motor activity complements the well-established inhibitory effect of leptin on food intake and adds an additional dimension to the regulation of energy balance by this hormone.

The growth cone is a highly motile tip structure that guides axonal elongation and directionality in differentiating neurons. Migrating immature neurons also exhibit a growth cone-like structure (GCLS) at the tip of the leading process. However, it remains unknown whether the GCLS in migrating immature neurons shares the morphological and molecular features of axonal growth cones and can thus be considered equivalent to them. Here, we describe a detailed method for time-lapse imaging and optical manipulation of growth cones using a super-resolution laser-scanning microscope. To observe growth cones in elongating axons and migrating neurons, embryonic cortical neurons and neonatal ventricular-subventricular zone (V-SVZ)-derived neurons, respectively, were transfected with plasmids encoding fluorescent protein-conjugated cytoskeletal probes and three-dimensionally cultured in Matrigel, which mimics the in vivo background. At 2-5 days in vitro, the morphology and dynamics of these growth cones and their associated cytoskeletal molecules were assessed by time-lapse super-resolution imaging. The use of photoswitchable cytoskeletal inhibitors, which can be reversibly and precisely controlled by laser illumination at two different wavelengths, revealed the spatiotemporal regulatory machinery and functional significance of growth cones in neuronal migration. Furthermore, machine learning-based methods enabled us to automatically segment growth cone morphology from elongating axons and the leading process. This protocol provides a cutting-edge methodology for studying the growth cone in developmental and regenerative neuroscience, being adaptable for various cell biology and imaging applications. Key features • Three-dimensional primary culture of migrating and differentiating neurons in Matrigel. • Visualization of fine morphology and dynamics of growth cones using super-resolution imaging. • Optical manipulation of cytoskeletal molecules in growth cones using photoswitchable inhibitors. • Machine learning-based extraction of growth cone morphology.

The mediodorsal (MD) thalamus is a critical partner for the prefrontal cortex (PFC) in cognitive control. Accumulating evidence has shown that the MD regulates task uncertainty in decision making and enhance cognitive flexibility. However, the computational mechanism of this cognitive process remains unclear. Here we trained biologically-constrained computational models to delineate the mechanistic role of MD in context-dependent decision making. We show that the addition of a feedforward MD structure to the recurrent PFC increases robustness to low cueing signal-to-noise ratio, enhances working memory, and enables rapid context switching. Incorporating genetically identified thalamocortical connectivity and interneuron cell types into the model replicates key neurophysiological findings in task-performing animals. Our model reveals computational mechanisms and geometric interpretations of MD in regulating cue uncertainty and context switching to enable cognitive flexibility. Our model makes experimentally testable predictions linking cognitive deficits with disrupted thalamocortical connectivity, prefrontal excitation-inhibition imbalance and dysfunctional inhibitory cell types.