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Enhanced oscillations at beta frequencies (8–30 Hz) are a signature neural dynamic pathology in the basal ganglia and cortex of Parkinson's disease patients. The mechanisms underlying these pathological beta oscillations remain elusive. Here, using mathematical models, we find that robust beta oscillations can emerge from inhibitory interactions between striatal medium spiny neurons. The interaction of the synaptic GABAa currents and the intrinsic membrane M-current promotes population oscillations in the beta frequency range. Increased levels of cholinergic drive, a condition relevant to the parkinsonian striatum, lead to enhanced beta oscillations in the striatal model. We show experimentally that direct infusion of the cholinergic agonist carbachol into the striatum, but not into the neighboring cortex, of the awake, normal rodent induces prominent beta frequency oscillations in the local field potential. These results provide evidence for amplification of normal striatal network dynamics as a mechanism responsible for the enhanced beta frequency oscillations in Parkinson's disease.

A holistic understanding of tissue and organ structure and function requires the detection of molecular constituents in their original three-dimensional (3D) context. Imaging mass cytometry (IMC) enables simultaneous detection of up to 40 antigens and transcripts using metal-tagged antibodies but has so far been restricted to two-dimensional imaging. Here we report the development of 3D IMC for multiplexed 3D tissue analysis at single-cell resolution and demonstrate the utility of the technology by analysis of human breast cancer samples. The resulting 3D models reveal cellular and microenvironmental heterogeneity and cell-level tissue organization not detectable in two dimensions. 3D IMC will prove powerful in the study of phenomena occurring in 3D space such as tumor cell invasion and is expected to provide invaluable insights into cellular microenvironments and tissue architecture.

Genomic alterations shape cell phenotypes and the structure of tumor ecosystems in poorly defined ways. To investigate these relationships, we used imaging mass cytometry to quantify the expression of 37 proteins with subcellular spatial resolution in 483 tumors from the METABRIC cohort. Single-cell analysis revealed cell phenotypes spanning epithelial, stromal and immune types. Distinct combinations of cell phenotypes and cell-cell interactions were associated with genomic subtypes of breast cancer. Epithelial luminal cell phenotypes separated into those predominantly impacted by mutations and those affected by copy number aberrations. Several features of tumor ecosystems, including cellular neighborhoods, were linked to prognosis, illustrating their clinical relevance. In summary, systematic analysis of single-cell phenotypic and spatial correlates of genomic alterations in cancer revealed how genomes shape both the composition and architecture of breast tumor ecosystems and will enable greater understanding of the phenotypic impact of genomic alterations.

Human and animal studies have converged to suggest that caffeine consumption prevents memory deficits in aging and Alzheimer’s disease through the antagonism of adenosine A 2A receptors (A 2A Rs). To test if A 2A R activation in the hippocampus is actually sufficient to impair memory function and to begin elucidating the intracellular pathways operated by A 2A R, we have developed a chimeric rhodopsin-A 2A R protein ( optoA 2A R ), which retains the extracellular and transmembrane domains of rhodopsin (conferring light responsiveness and eliminating adenosine-binding pockets) fused to the intracellular loop of A 2A R to confer specific A 2A R signaling. The specificity of the optoA 2A R signaling was confirmed by light-induced selective enhancement of cAMP and phospho-mitogen-activated protein kinase (p-MAPK) (but not cGMP) levels in human embryonic kidney 293 (HEK293) cells, which was abolished by a point mutation at the C terminal of A 2A R. Supporting its physiological relevance, optoA 2A R activation and the A 2A R agonist CGS21680 produced similar activation of cAMP and p-MAPK signaling in HEK293 cells, of p-MAPK in the nucleus accumbens and of c-Fos/phosphorylated-CREB (p-CREB) in the hippocampus, and similarly enhanced long-term potentiation in the hippocampus. Remarkably, optoA 2A R activation triggered a preferential p-CREB signaling in the hippocampus and impaired spatial memory performance, while optoA 2A R activation in the nucleus accumbens triggered MAPK signaling and modulated locomotor activity. This shows that the recruitment of intracellular A 2A R signaling in the hippocampus is sufficient to trigger memory dysfunction. Furthermore, the demonstration that the biased A 2A R signaling and functions depend on intracellular A 2A R loops prompts the possibility of targeting the intracellular A 2A R-interacting partners to selectively control different neuropsychiatric behaviors.

Dissecting neural circuitry in non-human primates (NHP) is crucial to identify potential neuromodulation anatomical targets for the treatment of pharmacoresistant neuropsychiatric diseases by electrical neuromodulation. How targets of deep brain stimulation (DBS) and cortical targets of transcranial magnetic stimulation (TMS) compare and might complement one another is an important question. Combining optogenetics and tractography may enable anatomo-functional characterization of large brain cortico-subcortical neural pathways. For the proof-of-concept this approach was used in the NHP brain to characterize the motor cortico-subthalamic pathway (m_CSP) which might be involved in DBS action mechanism in Parkinson’s disease (PD). Rabies-G-pseudotyped and Rabies-G-VSVg-pseudotyped EIAV lentiviral vectors encoding the opsin ChR2 gene were stereotaxically injected into the subthalamic nucleus (STN) and were retrogradely transported to the layer of the motor cortex projecting to STN. A precise anatomical mapping of this pathway was then performed using histology-guided high angular resolution MRI tractography guiding accurately cortical photostimulation of m_CSP origins. Photoexcitation of m_CSP axon terminals or m_CSP cortical origins modified the spikes distribution for photosensitive STN neurons firing rate in non-equivalent ways. Optogenetic tractography might help design preclinical neuromodulation studies in NHP models of neuropsychiatric disease choosing the most appropriate target for the tested hypothesis.

▪ Abstract  The cerebellum is an evolutionarily conserved structure critical for motor learning in vertebrates. The model that has influenced much of the work in the field for the past 30 years suggests that motor learning is mediated by a single plasticity mechanism in the cerebellum: long-term depression (LTD) of parallel fiber synapses onto Purkinje cells. However, recent studies of simple behaviors such as the vestibulo-ocular reflex (VOR) indicate that multiple plasticity mechanisms contribute to cerebellum-dependent learning. Multiple plasticity mechanisms may provide the flexibility required to store memories over different timescales, regulate the dynamics of movement, and allow bidirectional changes in movement amplitude. These plasticity mechanisms must act in combination with appropriate information-coding strategies to equip motor-learning systems with the ability to express learning in correct contexts. Studies of the patterns of generalization of motor learning in the VOR provide insight about the coding of information in neurons at sites of plasticity. These principles emerging from studies of the VOR are consistent with results concerning more complex behaviors and thus may reflect general principles of cerebellar function.

U-ExM enables near-native expansion microscopy of samples in vitro and in cells. The combination of U-ExM with confocal microscopy and HyVolution revealed details of centriole chirality that were previously accessible only by electron microscopy.

Human and animal studies have converged to suggest that caffeine consumption prevents memory deficits in aging and Alzheimer's disease through the antagonism of adenosine [A.sub.2A] receptors ([A.sub.2A]Rs). To test if [A.sub.2A]R activation in the hippocampus is actually sufficient to impair memory function and to begin elucidating the intracellular pathways operated by [A.sub.2A]R, we have developed a chimeric rhodopsin-[A.sub.2A]R protein (opto[A.sub.2A]R), which retains the extracellular and transmembrane domains of rhodopsin (conferring light responsiveness and eliminating adenosine-binding pockets) fused to the intracellular loop of [A.sub.2A]R to confer specific [A.sub.2A]R signaling. The specificity of the opto[A.sub.2A]R signaling was confirmed by light-induced selective enhancement of cAMP and phospho-mitogen-activated protein kinase (p-MAPK) (but not cGMP) levels in human embryonic kidney 293 (HEK293) cells, which was abolished by a point mutation at the C terminal of [A.sub.2A]R. Supporting its physiological relevance, opto[A.sub.2A]R activation and the [A.sub.2A]R agonist CGS21680 produced similar activation of cAMP and p-MAPK signaling in HEK293 cells, of p-MAPK in the nucleus accumbens and of c-Fos/phosphorylated-CREB (p-CREB) in the hippocampus, and similarly enhanced long-term potentiation in the hippocampus. Remarkably, opto[A.sub.2A]R activation triggered a preferential p-CREB signaling in the hippocampus and impaired spatial memory performance, while opto[A.sub.2A]R activation in the nucleus accumbens triggered MAPK signaling and modulated locomotor activity. This shows that the recruitment of intracellular [A.sub.2A]R signaling in the hippocampus is sufficient to trigger memory dysfunction. Furthermore, the demonstration that the biased [A.sub.2A]R signaling and functions depend on intracellular [A.sub.2A]R loops prompts the possibility of targeting the intracellular [A.sub.2A]R-interacting partners to selectively control different neuropsychiatric behaviors. Molecular Psychiatry (2015) 20, 1339-1349; doi: 10.1038/mp.2014.182; published online 17 February 2015

The heterogeneity of breast cancer plays a major role in drug response and resistance and has been extensively characterized at the genomic level. Here, a single-cell breast cancer mass cytometry (BCMC) panel is optimized to identify cell phenotypes and their oncogenic signalling states in a biobank of patient-derived tumour xenograft (PDTX) models representing the diversity of human breast cancer. The BCMC panel identifies 13 cellular phenotypes (11 human and 2 murine), associated with both breast cancer subtypes and specific genomic features. Pre-treatment cellular phenotypic composition is a determinant of response to anticancer therapies. Single-cell profiling also reveals drug-induced cellular phenotypic dynamics, unravelling previously unnoticed intra-tumour response diversity. The comprehensive view of the landscapes of cellular phenotypic heterogeneity in PDTXs uncovered by the BCMC panel, which is mirrored in primary human tumours, has profound implications for understanding and predicting therapy response and resistance. The heterogeneity of breast cancer has a major role in drug response and resistance. In this study, the authors use patient-derived tumour xenografts as a platform for drug testing and correlation with single-cell proteomic phenotypes characterized by mass cytometry.