THYMOS
A newsletter of research on Consciousness, Mind and Life

by piero scaruffi

Researchers are welcome to submit news and articles about breakthroughs and events in the areas of cognitive science, artificial intelligence, neurobiology, artificial life, linguistics, neural networks, connectionism, cognitive psychology, mind, philosophy, psychology, consciousness. Email the editor at this Email address. Readers who would like to receive periodic news and updates on cognitive science, philosophy of mind, neurobiology, artificial intelligence, etc, are invited to register to my mailing list.

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December 2020
November 2020
  • Bradley Lega's student Gray Umbach at University of Texas Southwestern has been able to observe time cells in the human hippocampus for the first time. Clearly, it is important that our episodic memory encodes temporal information, and "time cells" are the neurons in the hippocampus that attend to this task. He identified them in the medial temporal lobe of the human brain during memory encoding and retrieval. (paper)
  • Andrea Bari in Susumu Tonegawa's team at MIT identified specific brain circuits that focus attention: norepinephrine-producing neurons in the locus coeruleus, located deep into the brainstem. This area communicates via two different pathways with the prefrontal cortex, one that helps to ignore distractions and one that curbs impulses (paper)

October 2020
  • Yaoyao Jia at North Carolina State University has developed a wireless 5x3 square-millimeter chip that can be surgically implanted to read brain activity and to stimulate the brain with both light and electrical current. Besides reading neural signals and stimulating the brain, this chip can also shine light onto neurons that have been genetically modified to respond to specific wavelengths of light. (paper)
  • Some people are born without a corpus callosum (the link between the brain's two hemispheres). Vanessa Siffredi's team at the University of Geneva have detected significant neuronal plasticity in such patients. Their brain creates more intra-hemispheric connections (paper)

September 2020
  • Earl Miller of MIT and Mikael Lundqvist of Stockholm University have found that the information flow through the hierarchy of cortical regions corresponds to a change in brainwave frequency: higher regions (the ones that make sense of what is going on and decide how to act) use higher-frequency waves (theta and gamma), lower regions (the ones that initially process sensory information) use lower-frequency waves (alpha and beta). The beta band peaked at 11 Hz, parietal beta peaked at 15 Hz, and prefrontal beta peaked at 19 Hz, while gamma occurred at 65 Hz, parietal gamma topped at 72 Hz, and prefrontal gamma at 80 Hz. (paper)
  • An article written by GPT-3

August 2020
  • Nikolaus Weiskopf's team at the Max Planck Institute for Human Cognitive and Brain Sciences has made the superficial white matter of the brain (that covers the grey matter) visible in the human brain. This layer of the brain is largely a mystery because until now it was not possible to study it appropriately. Evgeniya Kirilina used Magnetic Resonance Imaging at a very high field strength (7 Tesla compared to typical 1.5 or 3 Tesla) in order to create high-resolution maps of the white-grey matter border throughout the entire brain. The team demonstrated that the superficial white matter contains a lot of iron, which creates a lot of myelin, which explains the white color. This white substance could be important for some brain functions. After all, myelin facilitates the transmission of information between neurons. (paper)
  • Several neurodegenerative disorders are caused by the death of neurons. Unfortunately, neurogenesis is rare after childhood and so we lose neurons all the time. David Hyde of the University of Notre Dame, in collaboration with Johns Hopkins University, Ohio State University and the University of Florida, has pinpointed the networks of genes that regulate the process of neuron regeneration. They have already been able to regenerate retinal neurons. (paper)

July 2020
  • Humans are the only animals known to have the ARHGAP11B gene. The ARHGAP11B gene protein is located in mitochondria. This gene causes the stem cells in the brain to multiply, in a manner similar to rapidly-dividing tumour cells (basal progenitor amplification). The result is an explosion of stem cells in the brain and a larger brain. That could be the single reason why the human neocortex is about three times bigger than that of our closest relatives, the chimpanzees. The mechanism was explained by Wieland Huttner's team at the Max Planck Institute for Molecular Cell Biology and Genetics. (paper). Now the same team, in collaboration with Hideyuki Okano of Keio University in Japan (a pioneer of the technology to generate transgenic non-human primates) and the Central Institute for Experimental Animals in Japan, transported the gene into monkeys (marmosets) and proved that it causes their brain to develop a larger neocortex. The same team had already shown (in 2015) that this was the case for mice and ferrets but this is the first time that the fact has been proven for another primate. The team believes that this gene evolved (about five million years ago) by partial duplication of ARHGAP11A, which is ubiquitous in animals. The ARHGAP11B protein contains a sequence of 47 amino acids that is not found in the ARHGAP11A protein, and this sequence could well be responsible for our bigger brain. In 2016 this team showed that these 47 amino acids are the result of a simple mistake, a single C-to-G base substitution in the gene, that probably occurred between 1.5 million and 500,000 years ago (which causes the loss of 55 nucleotides from the messenger RNA, which causes a shift in the reading frame, which causes the 47 amino acid sequence). The German-Japanese team generated baby transgenic marmosets equipped with the gene ARHGAP11B. After 101 days, the team measured their neocortex and found that it was both enlarged and folded, just like the human brain is (paper)

June 2020
  • Peter Mitchell of Royal Melbourne Hospital, in collaboration with the two professors who founded Synchron (Nicholas Opie and Thomas Oxley, co-directors of the Vascular Bionics Laboratory), developed a tiny wireless device called StentrodeT that was implanted in two patients who suffered from severe paralysis due to motor neuron disease. The patients are now able to use an eye-tracker for cursor navigation and this chip allowed them to type sentences at a typing speed of 14-20 characters per minute. (paper)

May 2020

April 2020
  • Sai Chavala's team at the University of North Texas Health Science Center was able to restore restore sight in mice by turning skin cells into light-sensing eye cells. They chemically (not genetically) reprogrammed skin cells to behave like rod photoreceptors, i.e. retinal cells, which were then transplanted into the eyes. The direct reprogramming used by Chavala's team is faster than the more famous genetic reprogramming of induced pluripotent stem-cells: it takes ten days where IPS reprogramming takes six months. (paper)

March 2020
  • John Loike wonders whether human-animal chimeras should be granted "personhood". Xenotransplantation is a combination of gene editing and stem-cell biology to create human-pig or human-sheep chimeras that can grow human organs (for example, kidneys) that can then transplanted into humans. Some day these methods can evolve to generate animals that incorporate human cells into their brains: would that animal now be human, at least to a degree? The question is: what is the percentage of human neurons that renders an animal a human being?

February 2020
  • The neuronal gene Arc seems to be important for long-term memory in the mammalian brain. Jason Shepherd at the University of Utah has discovered that the protein due to the expression of this gene self-assembles into a virus-like capsid that encapsulates RNA. Capsid is the protein shell of a virus. These capsids are released from the cell, delivering such RNA and proteins to neighboring cells (paper). One can speculate that cell-to-cell communication is, at least in some cases, a special case of viral infection. In fact, a genetic analysis of Arc shows that it has the same evolutionary ancestry as the HIV. One can speculate that some viruses evolved to become part of our brain functions, and that memory consolidation itself could be a form of "viral infection".

January 2020
  • Using a supercomputer and evolutionary algorithms, Michael Levin's student Sam Kriegman at Tufts Univ, computer scientist Joshua Bongard of the University of Vermont and microsurgeon Douglas Blackiston used a supercomputer to design tiny, millimeter-wide, programmable, living robots, or "xenobots": they repurposed living cells (from frog embryos) and re-assembled them into new life-forms. These are body forms that never existed in nature (paper)
  • Xenobots

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