Updated September 4th, 2024
Research Spotlight
Healthy adult brains generate alpha oscillations, and individual subjects have unique alpha oscillation frequencies, which impacts how they dynamically process, ignore, and attend to sensory information. Harlow and colleagues used a novel closed-loop technology and individualized approach to play sounds at physiologically distinct peak or trough phases of ongoing alpha oscillations. The authors found sounds played phase-locked to trough versus peak alpha phases measured with electroencephalography (EEG) elicit distinct brain potentials and changes in alpha oscillations. This study supports the feasibility of using a novel individualized, closed-loop, neuromodulation to investigate and potentially improve abnormal alpha and other oscillation activity associated with multiple neurological disorders.
Where in a fish’s brain is auditory information processed? Using a marker of neural activity (pS6) Corrales Parada and colleagues show that auditory stimulation activates the dorsal subdivision of the anterior tuberal nucleus in zebrafish diencephalon. The tract tracing confirmed that this region receives auditory inputs from a midbrain auditory region. The authors also provide a time course of pS6 phosphorylation, which is crucial for the effective usage of this marker in future neural activity studies.
Most-Discussed Research Published in July and August
Below are five Early Release articles that generated the most online discussion in July and August 2024, as measured by Altmetric. Altmetric data is available for all articles published in eNeuro on the Info & Metrics tab. Learn more about how the Altmetric score is calculated.
We developed an accessible, user-friendly, and open-source computational toolset for microglia morphology segmentation and analysis. While there has been considerable progress in the field to develop automated microglia morphology segmentation tools, the majority of published tools are not openly available or well documented, and there has been less transparency about the methods used to analyze the resulting morphological measures. Using our toolset, we took a data-informed approach to characterize different classes of microglia morphologies and to statistically model how membership across these forms dynamically changes across brain regions in an experimental mouse model. Application of our toolset will yield novel insights into microglia morphology differences at a single-cell resolution and in a spatially resolved manner across many different research questions.
Impact of Unitary Synaptic Inhibition on Spike Timing in Ventral Tegmental Area Dopamine Neurons
This study dissects the input–output relationship of ventral tegmental area dopamine neurons receiving inputs from single presynaptic inhibitory neurons. We measured unitary inhibitory postsynaptic currents from two major inhibitory inputs (the rostromedial tegmental nucleus and ventral pallidum) and simulated their impact on dopamine neuron firing based on new experimental data including the phase resetting curve and the reversal potential of the GABAA receptor-mediated currents. The results predict the impact of single and multiple unitary inhibitory postsynaptic conductances on spike timing and suggest that asynchronous, low-frequency inhibition can summate in a supralinear manner to powerfully slow or halt a dopamine neuron's firing.
GABAergic interneurons provide powerful inhibition to cortical circuits, by directly regulating the activity of other neurons through metabotropic GABAB receptors. While much is known about the basic properties of GABAB receptor signaling, current knowledge of the relative contribution made by specific interneuron subpopulations to this inhibitory neurotransmission mechanism is less well understood. Our results help address this knowledge gap by showing that the somatostatin-expressing interneuron subpopulation provide powerful GABAB receptor-mediated feedback inhibition in the mouse dentate gyrus. Furthermore, GABAB receptor activation in dentate gyrus was found to be tightly regulated by neuronal GABA uptake, and not astrocytes, thus providing self-regulated feedback inhibition. Together, these data provide novel insights into cell type-specific GABAB receptor-mediated control of dentate gyrus circuitry.
The scope of this work covers the analysis of in vitro electrophysiological recordings of neuronal populations derived from human pluripotent stem cells. The recordings were obtained using a state-of-the-art compartmentalized microfluidic device with an embedded microelectrode array (MEA) designed for in vitro modeling of a circular tripartite network of three spatially divergent brain areas. Neuronal signals were processed to explore the functioning of the neuronal networks. Custom MEA data analysis tools were developed to assess features of the formed networks, including circuitry-level synchronization and functional connectivity. The circular tripartite network model combined with an integrated analysis pipeline provides an opportunity for modeling neurological disorders and screening pharmacological compounds in vitro in a more validated manner.
In challenging listening conditions, people use focused attention to help understand individual talkers and ignore others, which changes their neural processing for speech at auditory through lexical levels. However, lexical processing for natural materials (e.g., conversations, audiobooks) has been difficult to measure, because of limitations of tools to estimate the predictability of individual words in longer discourses. The present investigation uses a contemporary large language model, GPT-4, to estimate word predictability, and demonstrates that listeners make online adaptations to their auditory neural processing in accord with these predictions; neural activity more closely tracks the acoustics of the target talker when words are less predictable from the context.
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