Axial Plane Optical Microscopy

We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues

Volumetric two-photon imaging of neurons using stereoscopy (vTwINS)

Two-photon laser scanning microscopy of calcium dynamics using fluorescent indicators is a widely used imaging method for large scale recording of neural activity in vivo. Here we introduce volumetric Two-photon Imaging of Neurons using Stereoscopy (vTwINS), a volumetric calcium imaging method that employs an elongated, V-shaped point spread function to image a 3D brain volume. Single neurons project to spatially displaced “image pairs” in the resulting 2D image, and the separation distance between images is proportional to depth in the volume. To demix the fluorescence time series of individual neurons, we introduce a novel orthogonal matching pursuit algorithm that also infers source locations within the 3D volume. We illustrate vTwINS by imaging neural population activity in mouse primary visual cortex and hippocampus. Our results demonstrate that vTwINS provides an effective method for volumetric two-photon calcium imaging that increases the number of neurons recorded while maintaining a high frame-rate

Patterned Photostimulation in the Brain

Photostimulation has been instrumental in the past two decades for studying the structural synaptic plasticity and functional connectivity of neuronal circuits. With the advent of optogenetic strategies, this approach has been further expanded and used to identify the neuronal substrates of behavior via monitoring and modulating the activity of specific neuronal types in vivo. To date, however, photostimulation has been mainly implemented via full-field illumination and laser scanning protocols, which suffer from limited selectivity and stop short of generating asynchronous and spatially distributed neuronal firing patterns, characteristic for brain activity

Striking lives: multiple narratives of South Asian women’s employment, identity and protest in the UK

This article draws on the narratives of the two groups of South Asian women (SAW) in the UK who took part in industrial disputes some 30 years apart, in order to examine the ways in which they have negotiated their way through their classed, racialized and gendered inclusion in the labour market. The comparison of the Grunwick and the Gate Gourmet disputes and the employment histories of the actors involved in these disputes enables us to explore the centrality of waged work to the social construction of a diasporic identity and the complexity of SAW’s identities in the UK. This article utilizes an intersectional framework, based on life history interviews, to reinterpret historical events by examining women’s experiences of industrial action in the context of their class backgrounds and changing class positions, and particular histories of migration and settlement

Genomic anatomy of the Tyrp1 (brown) deletion complex

Chromosome deletions in the mouse have proven invaluable in the dissection of gene function. The brown deletion complex comprises >28 independent genome rearrangements, which have been used to identify several functional loci on chromosome 4 required for normal embryonic and postnatal development. We have constructed a 172-bacterial artificial chromosome contig that spans this 22-megabase (Mb) interval and have produced a contiguous, finished, and manually annotated sequence from these clones. The deletion complex is strikingly gene-poor, containing only 52 protein-coding genes (of which only 39 are supported by human homologues) and has several further notable genomic features, including several segments of >1 Mb, apparently devoid of a coding sequence. We have used sequence polymorphisms to finely map the deletion breakpoints and identify strong candidate genes for the known phenotypes that map to this region, including three lethal loci (l4Rn1, l4Rn2, and l4Rn3) and the fitness mutant brown-associated fitness (baf). We have also characterized misexpression of the basonuclin homologue, Bnc2, associated with the inversion-mediated coat color mutant white-based brown (B(w)). This study provides a molecular insight into the basis of several characterized mouse mutants, which will allow further dissection of this region by targeted or chemical mutagenesis

Cortical Up states induce the selective weakening of subthreshold synaptic inputs

Slow-wave sleep is thought to be important for retuning cortical synapses, but the cellular mechanisms remain unresolved. During slow-wave activity, cortical neurons display synchronized transitions between depolarized Up states and hyperpolarized Down states. Here, using recordings from LIII pyramidal neurons from acute slices of mouse medial entorhinal cortex, we find that subthreshold inputs arriving during the Up state undergo synaptic weakening. This does not reflect a process of global synaptic downscaling, as it is dependent on presynaptic spiking, with network state encoded in the synaptically evoked spine Ca2+ responses. Our data indicate that the induction of synaptic weakening is under postsynaptic control, as it can be prevented by correlated postsynaptic spiking activity, and depends on postsynaptic NMDA receptors and GSK3β activity. This provides a mechanism by which slow-wave activity might bias synapses towards weakening, while preserving the synaptic connections within active neuronal assemblies