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Category: neuroscience – Page 101

July 17, 2024 – The changes can begin in middle age, but they’re not usually noticeable until decades later. By age 60 and beyond, the changes can pick up speed and may become obvious.

“As we get older, our brain actually starts to shrink and lose mass,” said Marc Milstein, PhD, a Los Angeles brain health researcher. The start of that shrinkage, as well as the path it takes, can vary, said Milstein, who wrote The Age-Proof Brain.

“Starting at 40, our overall brain volume can start shrinking about 5% every 10 years,” he said. “Our brain has connections where our memories are stored, and as we age, we lose some of these connections. That can make it challenging to remember and to learn new information.”

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Discussion at the Moving Naturalism Forward workshop, October 2012. Participants include Sean Carroll, Jerry Coyne, Richard Dawkins, Terrence Deacon, Simon DeDeo, Daniel Dennett, Owen Flangan, Rebecca Goldstein, Janna Levin, David Poeppel, Massimo Pigliucci, Nicholas Pritzker, Alex Rosenberg, Don Ross, and Steven Weinberg.

Visit https://www.preposterousuniverse.com/.… for more information.

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Keith Frankish is an Honorary Reader at the University of Sheffield, UK, a Visiting Research Fellow with The Open University, UK, and an Adjunct Professor with the Brain and Mind Programme at the University of Crete. He specializes in philosophy of mind, philosophy of psychology, and philosophy of cognitive science. His books include Illusionism: As a Theory of Consciousness, Consciousness: the Basics, and Consciousness.

/ friction.
/ discord.
/ frictionphilo.

00:00 — Introduction.
01:29 — René Descartes.
08:40 — Illusionism vs. eliminativism.
12:50 — Behaviorism.
15:22 — Perceptions vs. qualia.
17:35 — Color perception.
24:15 — Illusion for whom?
30:39 — Explaining the illusion.
43:44 — Identity theorist response?
50:13 — Diet qualia.
52:06 — Demonstratives and recognitional concepts.
56:53 — Physicalism and illusionism.
1:00:29 — Conceivability and possibility.
1:10:50 — Weakening acquaintance.
1:14:20 — Functionalism.
1:19:17 — Daniel Dennett.
1:23:03 — Mary’s room.
1:29:35 — Conclusion.

Possibilities by Jay Someday / jaysomeday

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The idea of the brain as a computer is everywhere. So much so we have forgotten it is a model and not the reality. It’s a metaphor that has lead some to believe that in the future they’ll be uploaded to the digital ether and thereby achieve immortality. It’s also a metaphor that garners billions of dollars in research funding every year. Yet researchers argue that when we dig down into our grey matter our biology is anything but algorithmic. And increasingly, critics contend that the model of the brain as computer is sending scientists (and their resources) nowhere fast. Is our attraction to the idea of the brain as computer an accident of current human technology? Can we find a better metaphor that might lead to a new paradigm?

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If there’s one phrase the June 2024 U.S. presidential debate may entirely eliminate from the English vocabulary it’s that age is a meaningless number. Often attributed to boxer Muhammad Ali, who grudgingly retired at age 39, this centuries-old idea has had far-reaching consequences in global politics, as life expectancy more than doubled since the start of the 20th century, and presidents’ ages shifted upwards. We say “age is what we make of it” to ourselves and to policymakers, and think it’s a harmless way to dignify the aged. But how true is it? And if it isn’t true, why would we lie?

For centuries, we have confused our narrative of what aging should be with what its ruthless biology is. Yet pretending that biological age does not matter is at best myopic, and at worst, it’s a dangerous story to our governments, families, and economies. In just 11 years — between 2018 and 2029 — U.S. spending on Social Security and Medicare will more than double, from $1.3 trillion to $2.7 trillion per year. As we age, our odds of getting sick and dying by basically anything go up exponentially. If smoking increases our chances of getting cancer by a factor of 15, aging does so 100-fold. At age 65, less than 5% of people are diagnosed with Alzheimer’s. Beyond age 85, nearly half the population has some form of dementia. Biological aging is the biggest risk factor for most chronic diseases; it’s a neglected factor in global pandemics; and it even plays a role in rare diseases.

This explains why in hospitals, if there’s one marker next to a patient’s name, it’s their age. How many birthday candles we have blown out is an archaic surrogate marker of biological aging. Yet it’s the best we have. Chronological age is so telling of overall health that physicians everywhere rely on it for life-or-death decisions, from evaluating the risks of cancer screening to rationing hospital beds.

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Analyzed the global trends in this area of neuroscience. To identify and further facilitate the development of cerebral organoids, we utilized bibliometrics and visualization methods to analyze the global trends and evolution of brain organoids in the last 10 years. First, annual publications, countries/regions, organizations, journals, authors, co-citations, and keywords relating to brain organoids were identified. The hotspots in this field were also systematically identified. Subsequently, current applications for brain organoids in neuroscience, including human neural development, neural disorders, infectious diseases, regenerative medicine, drug discovery, and toxicity assessment studies, are comprehensively discussed.

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Organoids are carefully grown collections of cells in a dish, designed to mimic organ structures and composition better than conventional cell cultures and give researchers a unique view into how organs such as the brain grow and develop. To make them experimentally useful, scientists need to determine how faithfully these models reproduce the behavior of cells in the body.

Now, researchers at the Broad Institute of MIT and Harvard and Harvard University have found that human brain organoids replicate many important cellular and molecular events of the developing human cortex, the part of the brain responsible for movement, perception, and thought. Their findings appear today in Cell.

The team grew brain organoids from stem cells and closely studied their growth over a six-month period, using tools that map cell position, gene expression, and chromatin accessibility — which determines how gene activity is regulated — at a single-cell level and over time. They then constructed an “atlas” characterizing more than 600,000 cells from organoids that were sampled as they developed and matured. The team found that after the first month, in each organoid they made, the same types of cells developed in the same order and expressed the same genes as cells in the developing human embryo.

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The dramatic advances in efferent neural interfaces over the past decade are remarkable, with cortical signals used to allow paralyzed patients to control the movement of a prosthetic limb or even their own hand. However, this success has thrown into relief, the relative lack of progress in our ability to restore somatosensation to these same patients. Somatosensation, including proprioception, the sense of limb position and movement, plays a crucial role in even basic motor tasks like reaching and walking. Its loss results in crippling deficits. Historical work dating back decades and even centuries has demonstrated that modality-specific sensations can be elicited by activating the central nervous system electrically. Recent work has focused on the challenge of refining these sensations by stimulating the somatosensory cortex (S1) directly. Animals are able to detect particular patterns of stimulation and even associate those patterns with particular sensory cues. Most of this work has involved areas of the somatosensory cortex that mediate the sense of touch. Very little corresponding work has been done for proprioception. Here we describe the effort to develop afferent neural interfaces through spatiotemporally precise intracortical microstimulation (ICMS). We review what is known of the cortical representation of proprioception, and describe recent work in our lab that demonstrates for the first time, that sensations like those of natural proprioception may be evoked by ICMS in S1. These preliminary findings are an important first step to the development of an afferent cortical interface to restore proprioception.

Keywords: Intracortical microstimulation (ICMS); Prosthesis; Somatosensation; Somatosensory cortex.

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