Lifeboat Foundation

Salk Institute researchers, as part of a larger collaboration with research teams around the world, analyzed more than half a million brain cells from three human brains to assemble an atlas of hundreds of cell types that make up a human brain in unprecedented detail.

The research, published in a special issue of the journal Science on October 13, 2023, is the first time that techniques to identify brain cell subtypes originally developed and applied in mice have been applied to human brains.

“These papers represent the first tests of whether these approaches can work in human brain samples, and we were excited at just how well they translated,” says Professor Joseph Ecker, director of Salk’s Genomic Analysis Laboratory and a Howard Hughes Medical Institute investigator. “This is really the beginning of a new era in brain science, where we will be able to better understand how brains develop, age, and are affected by disease.”

Whether in the brain or in the muscles, wherever there are nerve cells, there are synapses. These contact points between neurons form the basis for the transmission of excitation, the communication between neurons. As in any communication process, there is a sender and a receiver: Nerve cell processes called axons generate and transmit electrical signals thereby acting as signal senders.

Synapses are points of contact between axonal nerve terminals (the pre-synapse) and post-synaptic neurons. At these synapses, the electrical impulse is converted into chemical messengers that are received and sensed by the post-synapses of the neighboring neuron. The messengers are released from special membrane sacs called synaptic vesicles.

As well as transmitting information, synapses can also store information. While the structure and function of synapses are comparably well understood, little is known about how they are formed.

A quarter-century ago, researchers discovered that adults, not just developing infants, can generate new brain cells, a process called neurogenesis. But it’s still not clear what role these new neurons play in health or disease.

In a new mouse study, Columbia University researchers found that neurogenesis in adults is critical for maintaining brain circuits that support working memory across the lifespan and chronic loss of adult neurogenesis causes progressive memory loss, like that seen in age-related cognitive decline and Alzheimer’s disease in humans.

The study, “Adult-born neurons maintain hippocampal cholinergic inputs and support working memory during aging,” was published in July in the journal Molecular Psychiatry.

A study by researchers in the laboratory of Dr. Huda Zoghbi, distinguished service professor at Baylor College of Medicine and director of the Jan and Dan Duncan Neurological Research Institute (Duncan NRI) at Texas Children’s Hospital, has discovered that diminished memory recall in Rett syndrome mice can be restored by activating specific inhibitory cells in the hippocampus. The findings are published in the current edition of Neuron.

Rett syndrome is a neurodevelopmental disorder characterized by loss of acquired cognitive, motor, language and social skills after the first year of life as well as profound learning and memory impairments. In particular, contextual memories, those that encode an event and the circumstances in which the event was experienced, are diminished in mouse models of Rett syndrome. Previous research has suggested that diminished contextual memories result from disruptions in the finely tuned balance between excitatory and inhibitory synaptic inputs that constantly bombard hippocampal neurons.

Zoghbi’s team hypothesized that disruptions in this balance may alter the size and composition of ensembles of hippocampal neurons needed to encode a contextual memory. Using a miniature microscope, they directly monitored these ensembles as mice recalled a fearful experience. They found that Rett mice have larger and more correlated ensembles of neurons than wild-type mice, suggesting that hippocampal pyramidal neurons are not receiving enough inhibition in Rett mice.

Developing brains become shaped by the sights, sounds, and experiences of early life. The brain’s circuits grow more stable as we age. However, some experiences later in life open up opportunities for these circuits to be rapidly rewired. New research from Cold Spring Harbor Laboratory Associate Professor Stephen Shea helps explain how the brain adapts during a critical period of adulthood: the time when new mothers learn to care for their young.

Shea’s work in mice shows how this learning process is disrupted when a small set of neurons lack a protein called MECP2. In humans, MECP2 dysfunction causes the rare neurodevelopmental disorder Rett syndrome. Shea’s findings could point researchers toward the brain circuits involved in Rett syndrome and potential treatment strategies. His research could also have implications for more common neurological conditions.

Shea explains, “It’s not lost on us that Rett syndrome patients have difficulty interpreting and producing language. Difficulties with communicating are widespread in autism spectrum disorders. One of the reasons we study Rett syndrome is that this may be a valuable model for other forms of autism.”

Central learning and memory hubs change in response to sex hormones. A new study in Nature Mental Health by Rachel Zsido and Julia Sacher of the Max Planck Institute for Human Cognitive and Brain Sciences and the University Clinic in Leipzig, Germany, links rhythmic oscillations in ovarian hormone levels in women during the menstrual cycle to changes in brain structure.

Ovarian hormones have significant effects on the brain, and early menopause may be associated with an increased risk of accelerated brain aging and dementia later in life. However, the effects of ovarian hormone fluctuations on brain structure earlier in life are less defined. In their current study, Zsido and Sacher show that fluctuations in ovarian hormones affect structural plasticity in key brain regions during the reproductive years.

To do this, the scientists collected blood samples from 27 female study participants, used ultrasound to track follicle growth in the ovaries to pinpoint ovulation timing, and utilized ultra-high field 7 Tesla MRI to zoom into subregions of the medial temporal lobe and hippocampus. That’s because these regions are dense with sex hormone receptors and are critical for cognitive function, such as episodic memory.

In a move that echoes a sci-fi series, researchers have developed a super-small material that was able to not only stimulate nerves in rodents, but reconnect them as well. The finding could lead to injectable particles that take the place of larger implants.

In creating the particles, researchers at Rice University started with two layers of a metallic glass alloy called Metglas and wedged a piezoelectric layer of lead zirconium titanate in between them. Piezoelectric materials generate electricity when they have mechanical forces applied to them. Metglas is a magnetostrictive material, which means it changes its shape when it has a magnetic field applied to it. In this case, the change in shape of the Metglas in the presence of magnetic pulses caused the piezoelectric material inside to generate an electrical signal. Materials that do this are known as magnetoelectric.

“We asked, ‘Can we create a material that can be like dust or is so small that by placing just a sprinkle of it inside the body you’d be able to stimulate the brain or nervous system?’” said lead author Joshua Chen, a Rice doctoral alumnus. “With that question in mind, we thought that magnetoelectric materials were ideal candidates for use in neurostimulation. They respond to magnetic fields, which easily penetrate into the body, and convert them into electric fields – a language our nervous system already uses to relay information.”

The DOD is looking for tech that will protect against “cognitive attacks” that could disable soldiers wearing virtual reality devices.

In a suite of 21 papers published in the journals Science (12), Science Advances , and Science Translational Medicine , a large consortium of researchers shares new knowledge about the cells that make up our brains and the brains of other primates. It’s a huge leap from previously published work, with studies and data that reveal new insights about our nervous systems’ cellular makeup across many regions of the brain and what is distinctive about the human brain.

The research consortium is a concerted effort to understand the human brain and its modular, functional nature. It was brought together by the National Institutes of Health’s Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative.

Hundreds of scientists from around the world worked together to complete a range of studies exploring the cellular makeup of the human brain and those of other primates, and to demonstrate how a transformative new suite of scalable techniques can be used to study the detailed organization of the human brain at unprecedented resolution.