neuroscience

A team of neuroscientists from the International Brain Laboratory has described for the first time a virtually complete map of brain activity in mice during the decision-making process. To do so, they recorded the activity of more than half a million neurons across 12 different laboratories, representing 95% of brain volume. The map contradicts a hierarchical view of information processing and shows that decision-making is distributed in a coordinated manner across multiple brain areas. The results are published in two articles simultaneously in the journal Nature.

Various studies claimed that the loss of a limb caused a reorganisation of the “body map” integrated in the brain: neighbouring regions invaded and reused the brain area that previously represented the amputated limb. But a new study refutes this theory. Cortical representation remains stable even when the body suffers the loss of a limb. The team, which published its study in Nature Neuroscience, analysed three people who were about to undergo amputation of one of their hands, studying for the first time the maps of the hand and face before and after amputation, with follow-up for up to five years. Even without the hand, the corresponding brain region was activated in an almost identical way.

Researchers at Harvard Medical School have published new findings in Nature on the role of reduced lithium levels in Alzheimer's disease, based on experiments with mice and analysis of brain tissue and blood samples from humans. The team claims to have achieved improvements in memory in mouse models with lithium orotate. They caution that they have not proven that lithium is safe or effective in protecting against neurodegeneration in patients, and that their findings must be confirmed in humans through clinical trials.

Researchers in the United States have used stem cells created from patients with a very rare type of ALS, more prevalent in Brazil, to target a key gene in the stress response and reverse the damage suffered by motor neurons in the laboratory. They believe it is "a promising proof-of-concept for future therapeutic strategies" and "could help lay the foundation for genetically informed clinical trials".

A team from Sweden has analysed post mortem brain samples from people aged between 0 and 78 using various techniques and found that, although it varies between individuals, new neurons continue to form in the hippocampus with no apparent age limit. Although previous studies had reached similar conclusions, controversy remains about these results. According to the authors, the new work ‘provides an important piece of the puzzle in understanding how the human brain works and changes throughout life.’ The results are published in the journal Science.

The brain can become habituated to the deterioration of democracy, warn a neuroscientist and a law expert in an editorial published in Science Advances. "When democratic norms are violated repeatedly, people begin to adapt,’ they explain, calling for a "dishabituation" to democratic decline. This requires "see[ing] things not in light of the deterioration of recent years, but in light of our best historical practices, our largest ideals, and our highest aspirations.

An international study with 72 participants has found that greater connectivity between certain brain areas is associated with greater mathematical computational ability. In addition, weak electrical stimulation in a particular area was associated with improved computational learning in volunteers with lower connectivity. The results are published in the journal Plos Biology.  

A new study sheds light on how the brain adjusts its ‘wiring’ during learning, concluding that different dendritic segments of the same neuron follow different rules for communicating through their connections - synapses. The findings challenge the idea that neurons follow a single learning strategy and offer a new perspective on how the brain learns and adapts its behaviour. The work, carried out in mice, is published in the journal Science.

A set of articles published in Nature and Nature Methods draws a high-resolution map of the structure of and connections between the brain cells of mice. The map is based on data from a single cubic millimetre of brain and includes more than 200,000 cells, around 84,000 neurons and 524 million synaptic connections. Although this is a very small part of the mouse brain, it will help us understand how different types of cells work together.

A multidisciplinary team of researchers in the United States has implanted a paralysed person with a brain-computer interface capable of detecting and decoding finger movements. The system achieved a degree of accuracy that allowed him to play a video game. The results are published in the journal Nature Medicine.