The Dreams of Santiago Ramón y Cajal is both a portrait of Cajal’s legacy as well as a testament to the beauty and vulnerability that occurs when our brain and body communicates. Though Cajal’s legacy is monumental; he is lesser known than his pioneering counterparts such as Newton, Darwin, and Einstein. For those who are unfamiliar with Cajal, the first part of the book reads as a biography. Readers become acquainted with his life and work, which are heavily intertwined. Before Cajal, the brain was seen as a “continuous web” as opposed to the individual units known as neurons that Cajal discovered them to be through his use of the Golgi stain. He, as well as Golgi, received the Nobel Prize for his groundbreaking work on the structure of the nervous system in 1906.
Posts tagged neuroscience
Attribution of meaning and personal relevance is important for our everyday lives. In psychiatric disorders, the attribution of meaning is often altered, and the mechanisms causing this were unknown. LSD has also been shown to alter the attribution of meaning and personal relevance to the environment and our sense of self. However, the exact mechanism and brain structures had not been investigated yet. Therefore, LSD offered a unique opportunity to investigate these phenomena.
Is “now” expandable? Why do you seem to experience time in slow motion in a sudden emergency, like an accident? Eagleman’s (terrifying) experiments show that in fact you don’t perceive more densely, the amygdala cuts in and records the experience more densely, so when the brain looks back at that dense record, it thinks that time must have subjectively slowed down, but it didn’t. “Time and memory are inseparable.” This also explains why time seems to speed up as you age. A child experiences endless novelty, and each summer feels like it lasted forever. But you learn to automatize everything as you age, and novelty is reduced accordingly, apparently speeding time up. All you have to do to feel like you‘re living longer, with a life as rich as a child’s, is to never stop introducing novelty in your life.
The flip of a single molecular switch helps create the mature neuronal connections that allow the brain to bridge the gap between adolescent impressionability and adult stability. Now Yale School of Medicine researchers have reversed the process, recreating a youthful brain that facilitated both learning and healing in the adult mouse.
Scientists have long known that the young and old brains are very different. Adolescent brains are more malleable or plastic, which allows them to learn languages more quickly than adults and speeds recovery from brain injuries. The comparative rigidity of the adult brain results in part from the function of a single gene that slows the rapid change in synaptic connections between neurons.
By monitoring the synapses in living mice over weeks and months, Yale researchers have identified the key genetic switch for brain maturation a study released March 6 in the journal Neuron. The Nogo Receptor 1 gene is required to suppress high levels of plasticity in the adolescent brain and create the relatively quiescent levels of plasticity in adulthood. In mice without this gene, juvenile levels of brain plasticity persist throughout adulthood. When researchers blocked the function of this gene in old mice, they reset the old brain to adolescent levels of plasticity.
“These are the molecules the brain needs for the transition from adolescence to adulthood,” said Dr. Stephen Strittmatter. Vincent Coates Professor of Neurology, Professor of Neurobiology and senior author of the paper. “It suggests we can turn back the clock in the adult brain and recover from trauma the way kids recover.”
Rehabilitation after brain injuries like strokes requires that patients re-learn tasks such as moving a hand. Researchers found that adult mice lacking Nogo Receptor recovered from injury as quickly as adolescent mice and mastered new, complex motor tasks more quickly than adults with the receptor.
“This raises the potential that manipulating Nogo Receptor in humans might accelerate and magnify rehabilitation after brain injuries like strokes,” said Feras Akbik, Yale doctoral student who is first author of the study.
Researchers also showed that Nogo Receptor slows loss of memories. Mice without Nogo receptor lost stressful memories more quickly, suggesting that manipulating the receptor could help treat post-traumatic stress disorder.
“We know a lot about the early development of the brain,” Strittmatter said, “But we know amazingly little about what happens in the brain during late adolescence.”
LEHRER: You suggest that glia and their calcium waves might play a role in creativity. Could you explain? KOOB: This idea stems from dreams, sensory deprivation and day dreaming. Without input from our senses through neurons, how is it that we have such vivid thoughts? How is it that when we are deep in thought we seemingly shut off everything in the environment around us? In this theory, neurons are tied to our muscular action and external senses. We know astrocytes monitor neurons for this information. Similarly, they can induce neurons to fire. Therefore, astrocytes modulate neuron behavior. This could mean that calcium waves in astrocytes are our thinking mind. Neuronal activity without astrocyte processing is a simple reflex; anything more complicated might require astrocyte processing. The fact that humans have the most abundant and largest astrocytes of any animal and we are capable of creativity and imagination also lends credence to this speculation. Calcium is also released randomly and without stimulation from astrocytes’ internal stores in small bursts called ‘puffs.’ These random puffs can lead to waves. It is possible that the seemingly random thoughts during dreams and sensory deprivation experience could be calcium puffs becoming waves in our astrocytes. Basically, it is obvious that astrocytes are involved in brain processing in the cortex, but the main questions are, do our thoughts and imagination stem from astrocytes working together with neurons, or are our thoughts and imagination solely the domain of astrocytes? Maybe the role of neurons is to support astrocytes.
As neuroscientists continue to conduct brain stimulation experiments, publish results in journals and hold conferences, the D.I.Y. practitioners have remained quiet downstream listeners, blogging about scientists’ experiments, posting unrestricted versions of journal articles and linking to videos of conference talks. Some practitioners create their own manuals and guides based on published papers. The growth of D.I.Y. brain stimulation stems in part from a larger frustration with the exclusionary institutions of modern medicine, such as the exorbitant price of pharmaceuticals and the glacial pace at which new therapies trickle down to patients. For people without an institutional affiliation, even reading a journal article can be prohibitively expensive. The open letter this month is about safety. But it is also a recognition that these D.I.Y. practitioners are here to stay, at least for the time being. While the letter does not condone, neither does it condemn. It sticks to the facts and eschews paternalistic tones in favor of measured ones. The letter is the first instance I’m aware of in which scientists have directly addressed these D.I.Y. users. Though not quite an olive branch, it is a commendable step forward, one that demonstrates an awareness of a community of scientifically involved citizens.
We now know that if you take the same subject and do tDCS with exactly the same settings on different days, they can have very different responses. We know there’s a huge amount that can actually change what effect tDCS has. What you’re doing at the time tDCS is administered, or before tDCS is administered, has an effect. There are so many different things that can have an effect – your age, your gender, your hormones, whether you drank coffee that morning, whether you’ve had exposure to brain stimulation previously, your baseline neurotransmitter level — all of this stuff can affect what tDCS does to your brain. And some of those things vary on a day-to-day basis.
The ability to remember the past and imagine the future can significantly affect a person’s decisions in life. Scientists refer to the brain’s ability to think about the past, present, and future as “chronesthesia,” or mental time travel, although little is known about which parts of the brain are responsible for these conscious experiences. In a new study, researchers have used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of mental time travel and better understand the nature of the mental time in which the metaphorical “travel” occurs.
By administering mild electric currents to the brain, neuroscientists from Frankfurt University have successfully induced self-awareness in sleeping volunteers. Amazingly, the technique could be used to help people take better control of their dreams. But it’s also a discovery that’s offering critical insights into the very nature of consciousness itself. Gamma waves have been linked to consciousness before — a process called gamma coherence — but this is the first time scientists have used it to coax self-awareness during the dream cycle.
Enter the EyeWire project, an online game that recruits volunteers to map out those cellular contours within a mouse’s retina. The game was created and launched in December 2012 by a team led by H. Sebastian Seung, a neuroscientist at the Massachusetts Institute of Technology in Cambridge. Players navigate their way through the retina one 4.5-micrometer tissue block at a time, coloring the branches of neurons along the way. Most of the effort gets done in massive online competitions between players vying to map out the most volume. (Watch a video of a player walking through a tissue block here.) By last week, the 120,000 EyeWire players had completed 2.3 million blocks. That may sound like a lot, but it is less than 2% of the retina.
Resting-state activity is important, if the amount of energy devoted to it is any indication. Blood flow to the brain during rest is typically just 5–10% lower than during task-based experiments1. And studying the brain at rest should help to show how the active brain works. Research on resting-state networks is helping to map the brain’s intrinsic connections by showing, for example, which areas of the brain prefer to talk to which other areas, and how those patterns might differ in disease.