Morphoelectric and transcriptomic divergence of the layer 1 interneuron repertoire in human versus mouse neocortex

Neocortical layer 1 (L1) is a site of convergence between pyramidal-neuron dendrites and feedback axons where local inhibitory signaling can profoundly shape cortical processing. Evolutionary expansion of human neocortex is marked by distinctive pyramidal neurons with extensive L1 branching, but whether L1 interneurons are similarly diverse is underexplored. Using Patch-seq recordings from human neurosurgical tissue, we identified four transcriptomic subclasses with mouse L1 homologs, along with distinct subtypes and types unmatched in mouse L1. Subclass and subtype comparisons showed stronger transcriptomic differences in human L1 and were correlated with strong morphoelectric variability along dimensions distinct from mouse L1 variability. Accompanied by greater layer thickness and other cytoarchitecture changes, these findings suggest that L1 has diverged in evolution, reflecting the demands of regulating the expanded human neocortical circuit.

FIOLA: an accelerated pipeline for fluorescence imaging online analysis

Optical microscopy methods such as calcium and voltage imaging enable fast activity readout of large neuronal populations using light. However, the lack of corresponding advances in online algorithms has slowed progress in retrieving information about neural activity during or shortly after an experiment. This gap not only prevents the execution of real-time closed-loop experiments, but also hampers fast experiment-analysis-theory turnover for high-throughput imaging modalities. Reliable extraction of neural activity from fluorescence imaging frames at speeds compatible with indicator dynamics and imaging modalities poses a challenge. We therefore developed FIOLA, a framework for fluorescence imaging online analysis that extracts neuronal activity from calcium and voltage imaging movies at speeds one order of magnitude faster than state-of-the-art methods. FIOLA exploits algorithms optimized for parallel processing on GPUs and CPUs. We demonstrate reliable and scalable performance of FIOLA on both simulated and real calcium and voltage imaging datasets. Finally, we present an online experimental scenario to provide guidance in setting FIOLA parameters and to highlight the trade-offs of our approach.

High-fidelity estimates of spikes and subthreshold waveforms from 1-photon voltage imaging in vivo

The ability to probe the membrane potential of multiple genetically defined neurons simultaneously would have a profound impact on neuroscience research. Genetically encoded voltage indicators are a promising tool for this purpose, and recent developments have achieved a high signal-to-noise ratio in vivo with 1-photon fluorescence imaging. However, these recordings exhibit several sources of noise and signal extraction remains a challenge. We present an improved signal extraction pipeline, spike-guided penalized matrix decomposition-nonnegative matrix factorization (SGPMD-NMF), which resolves supra- and subthreshold voltages in vivo. The method incorporates biophysical and optical constraints. We validate the pipeline with simultaneous patch-clamp and optical recordings from mouse layer 1 in vivo and with simulated and composite datasets with realistic noise. We demonstrate applications to mouse hippocampus expressing paQuasAr3-s or SomArchon1, mouse cortex expressing SomArchon1 or Voltron, and zebrafish spines expressing zArchon1.

Assessing people with dementia: the role of the aged care assessment team and memory clinics

BACKGROUND

A cross-sectional survey of all patients reviewed by the aged care assessment team (ACAT) service and memory clinics between 1 January and 31 December 2012. The ACAT catchment included an estimated 14 325 people over the age of 70.

AIMS

To determine the numbers and outcomes of assessments for cognitive problems by the ACAT and hospital memory clinics for patients within a single ACAT catchment area.

METHODS

Data collected included patient demographics, diagnoses, referral and pharmacological treatment. Flow of referrals to the services that diagnose and manage dementia, and the number of incident dementia cases diagnosed in 2012 were determined.

RESULTS

The ACAT service assessed 1005 patients from the catchment, of which 241 patients already had a diagnosis of dementia. When compared with the estimated dementia prevalence in Australia, 19% of prevalent dementia cases (n = 1260) within the catchment were reviewed by the ACAT. The two memory clinics saw a combined 186 new referrals (91 and 95 respectively) from within the catchment, with a total of 82 patients (22 and 60 respectively) receiving a new diagnosis of dementia. Using Australian estimates of dementia incidence, this would suggest 29% of 286 incident cases were managed through these memory clinics.

CONCLUSIONS

Geriatric services are responsible for the assessment and management of a large proportion of the estimated number of patients with dementia in this catchment area. Further resourcing and standardisation of the pathways to dementia assessment is required in Australia in order to diagnose and manage effectively people with dementia.