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Category: neuroscience – Page 110

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How to explain our inner awareness that is at once most common and most mysterious? Traditional explanations focus at the level of neuron and neuronal circuits in the brain. But little real progress has motivated some to look much deeper, into the laws of physics — information theory, quantum mechanics, even postulating new laws of physics.

Watch more videos on consciousness as all physical: https://shorturl.at/PKpOk.

Sean Carroll is Homewood Professor of Natural Philosophy at Johns Hopkins University and fractal faculty at the Santa Fe Institute. His research focuses on fundamental physics and cosmology.

Continue reading “Sean Carroll — Physics of Consciousness” | >

Consciousness is comprised of arousal (i.e., wakefulness) and awareness. Substantial progress has been made in mapping the cortical networks that modulate awareness in the human brain, but knowledge about the subcortical networks that sustain arousal is lacking. We integrated data from ex vivo diffusion MRI, immunohistochemistry, and in vivo 7 Tesla functional MRI to map the connectivity of a subcortical arousal network that we postulate sustains wakefulness in the resting, conscious human brain, analogous to the cortical default mode network (DMN) that is believed to sustain self-awareness. We identified nodes of the proposed default ascending arousal network (dAAN) in the brainstem, hypothalamus, thalamus, and basal forebrain by correlating ex vivo diffusion MRI with immunohistochemistry in three human brain specimens from neurologically normal individuals scanned at 600–750 µm resolution. We performed deterministic and probabilistic tractography analyses of the diffusion MRI data to map dAAN intra-network connections and dAAN-DMN internetwork connections. Using a newly developed network-based autopsy of the human brain that integrates ex vivo MRI and histopathology, we identified projection, association, and commissural pathways linking dAAN nodes with one another and with cortical DMN nodes, providing a structural architecture for the integration of arousal and awareness in human consciousness. We release the ex vivo diffusion MRI data, corresponding immunohistochemistry data, network-based autopsy methods, and a new brainstem dAAN atlas to support efforts to map the connectivity of human consciousness.

One sentence summary We performed ex vivo diffusion MRI, immunohistochemistry, and in vivo 7 Tesla functional MRI to map brainstem connections that sustain wakefulness in human consciousness.

BF has a financial interest in CorticoMetrics, a company whose medical pursuits focus on brain imaging and measurement technologies. BF’s interests were reviewed and are managed by Massachusetts General Hospital and Mass General Brigham HealthCare in accordance with their conflict-of-interest policies.

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Is consciousness a scientific problem to be solved? Or a philosophical problem that will remain a mystery? What do scientists who study the brain think? And why do they think the way they do? These leading brain scientists share their intimate ideas about how the brain generates consciousness.

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Watch more interviews on neuroscience and the hard problem of consciousness: https://bit.ly/3NZ2gn5

Arnold B. Scheibel was a Professor of Neurobiology and Psychiatry and former Director of the Brain Research Institute (BRI) at UCLA.

Continue reading “How Brain Scientists Think About Consciousness” | >

Learn more about the Cognitive Science Student Association and the California Cognitive Science Conference at https://cssa.berkeley.edu.

Amy Arnsten — Yale University.

Abstract.
The recently evolved prefrontal cortex (PFC) subserves many of our highest-order cognitive functions, generating and sustaining the mental representations that underlie working memory, abstract reasoning, and top-down control of thought, action, and emotion. Due to the pioneering research of Patricia Goldman-Rakic, we have learned much about the neural basis underlying the ability of the dorsolateral prefrontal cortex (dlPFC) to generate mental representations, where microcircuits in deep layer III have extensive recurrent excitatory connections to maintain neuronal firing in the absence of sensory stimulation, while GABAergic interneurons provide lateral inhibition to refine the contents of working memory. However, these dlPFC circuits are also tremendously dependent on arousal state, with a narrow inverted U response to levels of acetylcholine, dopamine and norepinephrine. Even quite mild uncontrollable stress increases the release of dopamine and norepinephrine in the PFC, which rapidly impairs PFC functioning by 1) stimulating D1 and alpha-1-receptors, respectively, 2) these, in turn, activate feedforward calcium-cAMP signaling within spines, which then 3) open nearby potassium channels to disconnect PFC networks and take the PFC “off-line”. With chronic stress exposure, there is actual atrophy of PFC dendrites and spines. Understanding the neural events that weaken vs. strengthen PFC connectivity and function has led to the development of treatments for patients with stress-related PFC dysfunction, e.g. guanfacine and prazosin. This knowledge is also helping to illuminate the etiology of cognitive disorders, as genetic insults in schizophrenia often increase the activity of these stress signaling pathways, and the molecules that regulate the stress signaling pathways are lost with advancing age, leading to tau pathology as seen in Alzheimer’s disease.

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The largest animals do not have proportionally bigger brains — with humans bucking this trend — a new study published in Nature Ecology and Evolution has revealed.

Researchers at the University of Reading and Durham University collected an enormous dataset of brain and body sizes from around 1,500…

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Toronto, Ontario —A new ultra-high-performance brain PET system allows for the direct measurement of brain nuclei as never before seen or quantified. With its ultra-high sensitivity and resolution, the NeuroEXPLORER provides exceptional brain PET images and has the potential to spur advances in the treatment of many brain diseases. This research was presented at the 2024 Society of Nuclear Medicine and Molecular Imaging (SNMMI) Annual Meeting, and the grouping of images highlighting targeted tracer uptake in specific brain nuclei has been selected as the 2024 SNMMI Henry N. Wagner, Jr., Image of the Year.

Each year, SNMMI chooses an image that best exemplifies the most promising advances in the field of nuclear medicine and molecular imaging. The state-of-the-art technologies captured in these images demonstrate the capacity to improve patient care by detecting disease, aiding diagnosis, improving clinical confidence, and providing a means of selecting appropriate treatments. This year, the SNMMI Image of the Year was chosen from more than 1,500 abstracts submitted for the meeting.

The image quality of PET systems has improved in recent years, mostly by increases in sensitivity, including enhanced time-of-flight capabilities. However, these systems have shown only minimal improvement in intrinsic resolution. To address these issues, researchers designed the NeuroEXPLORER PET scanner with a focus on ultra-high sensitivity and resolution, as well as continuous head motion correction.

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The largest animals do not have proportionally bigger brains—with humans bucking this trend—a study published in Nature Ecology & Evolution has revealed.

Researchers at the University of Reading and Durham University collected an enormous dataset of brain and body sizes from around 1,500 species to clarify centuries of controversy surrounding brain size evolution.

Bigger brains relative to are linked to intelligence, sociality, and behavioral complexity—with humans having evolved exceptionally large brains. The new research reveals the largest animals do not have proportionally bigger brains, challenging long-held beliefs about brain evolution.

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Researchers at the Okinawa Institute of Science and Technology (OIST) have developed a potentially transformative approach to treating Alzheimer’s disease, A team from the former Cellular and Molecular Synaptic Function Unit have reported significant progress in reversing cognitive decline and restoring memory in transgenic mice using a synthetic protein. The findings, published in Brain Research, offer hope for a viable treatment to alleviate the debilitating symptoms associated with this neurodegenerative condition.

“We successfully reversed the symptoms of Alzheimer’s disease in mice,” explained Dr Chia-Jung Chang, first author of the study and presently a member of the Neural Computation Unit at OIST. “We achieved this with a small, synthetic peptide, PHDP5, that can easily cross the blood-brain barrier to directly target the memory center in the brain [1].”

Longevity. Technology: There is a pressing need to find effective treatments for Alzheimer’s; along with other forms of dementia, this debilitating disease currently affects approximately 55 million people worldwide, and this number is predicted to nearly double every 20 years, reaching 78 million in 2030 and 139 million in 2050. As well as a health burden, Alzheimer’s is an economic burden – the annual global cost of dementia has now rocketed to more than US$1.3 trillion, with a projected rise to US$2.8 trillion by 2030 on the horizon [2].

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