Updated November 05, 2019
Research Spotlight
Electroencephalographic Signatures of the Neural Representation of Speech During Selective Attention
Using electroencephalography (EEG), Viswanathan et al. investigated how a mixture of two running speech streams is represented in the brain when attention is selectively directed to one stream versus the other. They found that brain rhythms in the delta, theta, and low-gamma frequency bands selectively track attended speech over ignored speech, but that there are large individual differences in the strength and pattern of attention effects. These results can inform models of selective attention, and guide the development of individualized brain-computer interface applications including EEG-guided hearing aids that can sense listener attention.
The neuronal potassium-chloride cotransporter KCC2 is dysregulated after numerous types of neuronal injuries and has been related to neuronal dysfunction, hyperalgesia and spasticity. In this study, we investigated KCC2 regulation on spinal motoneurons with axons injured during peripheral nerve transections. We illustrate that KCC2 loss on axotomized motoneurons occurs at the transcriptional level. This loss differs in time course, completeness and signaling mechanisms from KCC2 dysregulation in other neurons after various pathologies or in motoneurons after spinal cord injury (SCI). In contrast, KCC2 loss on axotomized motoneurons relates to muscle innervation, suggesting a dependence on target-derived signals. We argue that KCC2 loss in axotomized motoneurons may be part of the response that facilitates regeneration of motor axons in the periphery.
Also of Interest
Fast, Flexible Closed-Loop Feedback: Tracking Movement in “Real-Millisecond-Time”
Here, we implemented a method for tracking and reacting to movement in real time at low latency, i.e., in 2 ms. We use a neuromorphic camera chip to track movement of a whisker and generate an output based on whisker position. With training, mice learn to move whiskers to virtual target locations. Combined with the recent sophisticated techniques for monitoring and manipulating brain activity, methods like ours can be used to manipulate behavior or neural circuits that help animals adapt to changing values of a sequence of motor actions.
Given the common practice of excluding female animals from studies of maternal immune activation during pregnancy, it appears to be widely assumed that female outcomes are simply attenuated versions of more severe male outcomes. However, when females fetuses and offspring are closely examined in a model of lipopolysaccharide-induced maternal inflammation during pregnancy, we find that sex confers selective vulnerabilities and outcomes that impact the placenta, fetal brain, adult brain, and behavior in ways that are categorically distinct and in some cases opposite between females and males. Therefore, the effect of maternal immune activation on female offspring cannot be inferred from male outcomes and must be studied independently to fully understand the mechanisms that underlie prenatal vulnerability to maternal insults.
Compound Stimuli Reveal the Structure of Visual Motion Selectivity in Macaque MT Neurons
How do sensory systems build representations of complex features from simpler ones? Visual motion representation in cortex is a well-studied example: the direction and speed of moving objects, regardless of shape or texture, is computed from the local motion of oriented edges. Here we quantify tuning properties based on single-unit recordings in primate area MT, then fit a novel, generalized model of motion computation. The model reveals two core properties of MT neurons — speed tuning and invariance to local edge orientation — result from a single organizing principle: each MT neuron combines afferents that represent edge motions consistent with a common velocity, much as V1 simple cells combine thalamic inputs consistent with a common orientation.
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