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Category: neuroscience – Page 322

The results of a human study carried out by an international research team have provided valuable new insights into the activity of the brain’s noradrenaline (NA) system, which has been a longtime target for medications to treat attention-deficit/hyperactivity disorder, depression, and anxiety. The study employed what the researchers claim is a groundbreaking methodology, developed to record real-time chemical activity from standard clinical electrodes implanted into the brain routinely for epilepsy monitoring.

The results offer up new insights into brain chemistry, which could have implications for a wide array of medical conditions, and also demonstrate use of the new strategy for acquiring data from the living human brain.

“Our group is describing the first ‘fast’ neurochemistry recorded by voltammetry from conscious humans,” said Read Montague, PhD, the VTC Vernon Mountcastle research professor at Virginia Tech, and director of the Center for Human Neuroscience Research and the Human Neuroimaging Laboratory of the Fralin Biomedical Research Institute at VTC. “This is a big step forward and the methodological approach was implemented completely in humans – after more than 11 years of extensive development.” Montague is senior, and co-corresponding author of the researchers’ published paper in Current Biology, which is titled “Noradrenaline tracks emotional modulation of attention in human amygdala.” In their paper the authors concluded, “By showing that neuromodulator estimates can be obtained from depth electrodes already in standard clinical use in the conscious human brain, our study opens the door to a new area of research on the neuromodulatory basis of human health and disease.”

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When scientists measure a particle, it seems to collapse to one fixed state. Yet no one can be sure what’s causing collapse, also called reduction of the state. Some scientists and philosophers even think that wave function collapse is an elaborate illusion. This debate is called the measurement problem in quantum mechanics.

The measurement problem has led many physicists and philosophers to believe that a conscious observer is somehow acting on quantum particles. One proposal is that a conscious observer causes collapse. Another theory is that a conscious observer causes the universe to split apart, spiralling out alternate realities. These worlds would be parallel yet inaccessible to us so that we only ever see things in one single state in whatever possible world we’re stuck in. This is the Multiverse or Many Worlds theory. “The point of view that it is consciousness that reduces the state is really an absurdity,” says Penrose, adding that a belief in Many Worlds is a phase that every physicist, including himself, eventually outgrows. “I shouldn’t be so blunt because very distinguished people seem to have taken that view.” Penrose demurs. He politely but unequivocally waves off the idea that a conscious observer collapses wave functions by looking at them. Likewise, he dismisses the view that a conscious observer spins off near infinite universes with a glance. “That’s making consciousness do the job of collapsing the wave function without having a theory of consciousness,” says Penrose. “I’m turning it around and I’m saying whatever consciousness is, for quite different reasons, I think it does depend on the collapse of the wave function. On that physical process.”

What’s causing collapse? “It’s an objective phenomenon,” insists Penrose. He’s convinced this objective phenomenon has to be the fundamental force: gravity. Gravity is a central player in all of classical physics conspicuously missing from quantum mechanics.

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Stress may enhance the brain’s ability to encode and store memory, a new Yale study finds.

A team led by Yale Department of Psychiatry’s Elizabeth Goldfarb, PhD, found study participants were more able to remember specific pairings of images after taking cortisol, a key stress hormone.

“We discovered this pathway where cortisol is helping the hippocampus talk to itself, and that helps people remember emotional experiences better,” Goldfarb says.

The hippocampus is a key brain region involved in encoding memory. Cortisol boosts connectivity in this region to enhance memory, according to Yale researchers.

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Stupendous paper on a new spatial transcriptomic atlas of mouse brain by Shi et al. from Xiao Wang’s group at MIT. They leverage their in situ sequencing method “STARmap PLUS” to profile 1,022 genes in 3D and map 1.09 million cells across the adult mouse brain and spinal cord. While they did not use the whole brain, instead opting for a series of thick sections at regular intervals, they still covered a lot of ground! Furthermore, they employed graph-theoretic computational methods to predict wider gene expression profiles of cells in their dataset, imputing single-cell expression profiles of 11,844 genes. This dataset/resource will serve the neurobiology community in elucidating the mechanistic workings of the brain!

In situ spatial transcriptomic analysis of more than 1 million cells are used to create a 200-nm-resolution spatial molecular atlas of the adult mouse central nervous system and identify previously unknown tissue architectures.

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Investigators have discovered a new subtype of interneurons in the retina that allows the eye to see and identify objects better in both the light and in the dark, according to a Northwestern Medicine study published in Nature Communications.

The findings dismantle previous notions about the inner workings of the eye and also have broader implications for informing future neuroscience research, according to Yongling Zhu, Ph.D., assistant professor of Ophthalmology, of Neuroscience and senior author of the study.

In a mammalian eye, the retina converts light into that the then sends to the brain, enabling vision. Before being transmitted to the brain, the electrical signals are processed in a dense, synaptic layer within the retina, which is divided into two halves.

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Findings could help scientists develop regenerative therapies for spinal cord injuries and other neurological conditions.

Neurons, the main cells that make up our brain and spinal cord, are among the slowest cells to regenerate after an injury, and many neurons fail to regenerate entirely. While scientists have made progress in understanding neuronal regeneration, it remains unknown why some neurons regenerate and others do not.

Using single-cell RNA.

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When humans make decisions, such as picking what to eat from a menu, what jumper to buy at a store, what political candidate to vote for, and so on, they might be more or less confident with their choice. If we are less confident and thus experience greater uncertainty in relation to their choice, our choices also tend to be less consistent, meaning that we will be more likely to change our mind before reaching a final decision.

While neuroscientists have been exploring the neural underpinnings decision-making for decades, many questions are still unanswered. For instance, how neural network computations support decision-making under varying levels of certainty remain poorly understood.

Researchers at the National Institute of Mental Health in Bethesda, Maryland recently carried out a study on aimed at better understanding the neural network dynamics associated with decision confidence. Their paper, published in Nature Neuroscience, offers evidence that energy landscapes in the can predict the consistency of choices made by monkeys, which is in turn a sign of the animals’ confidence in their decisions.

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The parabrachial nuclear complex (PBN) is a nexus for aversion and for the sensory and affective components of pain perception. We have previously shown that during chronic pain PBN neurons in anesthetized rodents have amplified activity. We report a method to record from PBN neurons of behaving, head-restrained mice while applying reproducible noxious stimuli. We find that both spontaneous and evoked activity are higher in awake animals compared with urethane anesthetized mice. Fiber photometry of calcium responses from calcitonin-gene-related peptide–expressing PBN neurons demonstrates that these neurons respond to noxious stimuli. In both males and females with neuropathic or inflammatory pain, responses of PBN neurons remain amplified for at least 5 weeks, in parallel with increased pain metrics. We also show that PBN neurons can be rapidly conditioned to respond to innocuous stimuli after pairing with noxious stimuli. Finally, we demonstrate that changes in PBN neuronal activity are correlated with changes in arousal, measured as changes in pupil area.

SIGNIFICANCE STATEMENT The parabrachial complex is a nexus of aversion, including pain. We report a method to record from parabrachial nucleus neurons of behaving mice while applying reproducible noxious stimuli. This allowed us to track parabrachial activity over time in animals with neuropathic or inflammatory pain. It also allowed us to show that the activity of these neurons correlates with arousal states and that these neurons can be conditioned to respond to innocuous stimuli.

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