neuroscience

The prefrontal cortex is a brain region involved in some of the defining characteristics of human beings, such as planning, complex problem-solving, and impulse regulation. Researchers from the PsychAD consortium have created the most comprehensive map to date of gene expression in this region across the lifespan. According to the authors, the maturation process is complete by approximately age 24. The study—which will facilitate research into aspects of aging and cognitive decline—is published in Nature alongside seven other papers describing disease-related alterations and new genetic risk factors.

A US-based team with Spanish participation has successfully transplanted cortical organoids—self-organizing fragments of lab-grown human brain tissue—into modified mice lacking most of their cerebral cortex, the brain layer responsible for functions ranging from cognition and language to attention and decision-making. The research, published in the journal Nature, shows that the human tissue survived, grew, and developed functional connections with the mice's brains and, extending beyond that, with the spinal cord. According to the authors, this could help generate new models for studying disease-related alterations in human brain circuits.

A new study reveals that the proportion of adults with dementia has risen significantly in Mexico, Peru and Puerto Rico over the last two decades, rising from one in ten older adults to almost one in six; a trend that runs counter to that seen in the US and other wealthy countries. Rates remained stable in Cuba and the Dominican Republic. The authors urge investment in prevention, dementia screening and care infrastructure. The study is published in JAMA Neurology.

An article published in Brain Health proposes using the concept of the ‘criticome’ to refer to the sensory, motor, social, cultural and environmental information recorded from pregnancy up to the age of 25, which is the period of greatest brain plasticity. According to the authors, this concept reframes autism, schizophrenia and depression as developmental disorders rather than purely synaptic disorders. Besides, they say this approach would have implications for educational policy, mental health care and screen use, amongst other issues.

The eyes are connected to the brain via the retina, which makes it a potential pathway for brain stimulation. A study published in Cell Reports Physical Science has used contact lenses equipped with a system for transcorneal electrical stimulation to treat depression in animal models of the disorder. Mice fitted with the device showed behavioural improvements, including increased sociability, as well as physiological changes, such as the restoration of altered neural connections. The results were comparable to those obtained with fluoxetine —known commercially as Prozac— administered for three weeks in one of the mouse groups.

The hallucinogen psilocybin, found in certain mushrooms, is being investigated as a treatment for conditions such as depression. A study published in Nature Communications shows that a single 25 mg dose of the compound can produce brain changes lasting up to a month after administration. These were measured using neuroimaging techniques in 28 healthy adults who had never taken psychedelics. In terms of psychological effects, participants showed increased cognitive flexibility, psychological insight, and well-being after one month.

Autism spectrum disorders are often accompanied by social communication difficulties, which are treated through behavioral interventions. A type of transcranial magnetic stimulation, accelerated continuous theta-burst stimulation, has demonstrated efficacy and safety in improving this aspect in a clinical trial published in the BMJ. The trial included 200 children from China (167 boys and 33 girls) aged 4 to 10 with autism spectrum disorder, half of whom had intellectual disabilities. One group of participants received 10 daily sessions targeting the motor cortex over five consecutive days, while the other group received sham sessions. The treated group showed greater improvements in both social communication and language skills for one month following treatment.

A study published in Science analyzed more than 100,000 human neocortical cells from weeks 13 to 23 of gestation, when cortical neurons are generated. The samples came from 26 donors, some with and others without Down syndrome. Using single-cell genomics, they observed how trisomy 21 disrupts the developmental sequence of various types of neurons, which could explain subsequent differences in cognition. A second study in the same journal, which examines the postnatal brains of children with Down syndrome, finds that many of these changes persist into childhood. The authors note that their study will not have short-term clinical applications, but they hope it can be used to develop specific drugs or create gene therapies. 

A US team analyzed the genetic activity of individual brain cells from 15 men and 15 women and found 133 genes that showed consistent differences. Although biological sex explained only a small part of the differences they found when comparing all the brains, variants in many of these genes have been associated with neuropsychiatric and neurodegenerative disorders—such as ADHD, schizophrenia, depression, and Alzheimer's—suggesting that sex differences could play a role in the distinct risk men and women have of developing certain diseases. The authors, however, acknowledge that the sex-related differences in their study could stem from differences in socialization and experience. The results are published in Science.  

Various studies have shown that exercise benefits the brain. Now, an international team has studied in mice how physical activity affects the brain and how these changes influence the effects of exercise. The research, published in Neuron, has shown that physical activity causes brain changes in a region of the hypothalamus involved in how the body uses energy and in regulating blood sugar. If these neurons were blocked immediately after exercise, the animals showed no improvement in endurance or metabolism with training. The authors suggest that activating these neurons may help the body recover faster, allowing other parts, such as the muscles, lungs, and heart, to adapt more quickly to more intense workouts.