Updated July 16, 2019
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Determination of postsynaptic targets, shape and size of the synaptic junctions provide critical data on synaptic functionality. This study is the first attempt to unveil the synaptic organization of the neuropil of the human cerebral cortex using 3D electron microscopy. The results provide a new, large, quantitative ultrastructure dataset of the synaptic organization of the normal human cortex and synaptic alterations that occur in Alzheimer’s disease.
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Rodent Activity Detector (RAD), an Open Source Device for Measuring Activity in Rodent Home Cages
Physical activity is an important determinant of human health, which reduces the risk of cardiovascular, metabolic and neurologic disorders. Better methods for tracking physical activity in research studies may lead to insights that improve physical activity levels in people. To this end, we designed and built an inexpensive device to continuously track home-cage activity levels in rodents. Our device, rodent activity detector (RAD), allows for high-throughput activity monitoring with minimal investigator intervention, presenting an economical and efficient option for investigating physical activity levels in research studies.
Each member of a species is unique, down to its neurons. The ability to experimentally identify a specific neuron across individuals allows investigating the neuron’s variability in spiking activity patterns and therefore its function. Identified neuron types produce stereotypical, albeit individually unique, activity patterns. Uniqueness of activity can be caused by variability observed in the intrinsic properties of neurons and the synaptic connections of the circuit. Here, we propose that, for a rhythmic neuronal motor circuit, the uniqueness derives mainly from differences in synaptic strength rather than from differences in intrinsic membrane conductances. The neuron types that we studied are from the leech heartbeat system. However, our results are general and can translate to other neuronal networks that control output phasing.
Sex Differences in Cognitive Flexibility and Resting Brain Networks in Middle-Aged Marmosets
We examined sex differences in multiple outcomes (cognition, motor function, stress reactivity and resting state functional connectivity) in middle-aged marmosets. We found that female marmosets had poorer reversal learning relative to males. Resting state functional connectivity analyses revealed substantial sex differences in cognitive networks, with differences in both overall neural network metrics and specific regions, including the prefrontal cortex, caudate, putamen, and nucleus accumbens. Sex-dependent correlations between reversal learning and neural connectivity measures indicate that the sex difference in cognitive performance is related to sex-dependent patterns of resting brain networks. Although these data are correlational and cannot determine causal effects, they are consistent with human resting state data, supporting the idea that cognitive sex differences have identifiable intrinsic neural correlates.
To understand the role of the basolateral nucleus of the amygdala (BLA) in the retrieval of conditioned taste aversion (CTA), we developed a new behavioral paradigm that overcomes the limitations of traditional behavioral procedures in CTA studies. In male rats, we measured time stamps of the approach behavior to a conditioned stimulus (CS) and licking of a spout. BLA inactivation not only increased CS consumption but also decreased avoidance and aversion to the CS. These results reveal that the BLA is essential for CTA retrieval by processing two distinct behavioral responses in parallel: avoidance and palatability. We further demonstrate that multi-dimensional analysis of animal behavior is an important factor for elucidating brain function.
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