healthcare technology

As we move through the world, what we see is seamlessly integrated with our memory of the broader spatial environment.

How does the brain accomplish this feat? A new study from Dartmouth College reveals that three regions of the brain in the posterior cerebral cortex, which the researchers call "place-memory areas," form a link between the brain's perceptual and memory systems. The findings are published in Nature Communications.

For the study, an innovative methodology was employed. Participants were asked to perceive and recall places that they had been to in the real world during functional magnetic resonance imaging (fMRI), which produced high-resolution, subject specific maps of brain activity. Past studies on scene perception and memory have often used stimuli that participants knew of but had never visited, like famous landmarks, and have pooled data across many subjects. By mapping the brain activity of individual participants using real-world places that they had been to, researchers were able to untangle the brain's fine-grained organization.

In one experiment, 14 participants provided a list of people that they knew personally and places that they have visited in real-life (e.g., their father or their childhood home). Then, while in the fMRI scanner, the participants imagined that they were seeing those people or visiting those places. Comparing the brain activity between people and places revealed the place-memory areas. Importantly, when the researchers compared these newly identified regions to the brain areas that process visual scenes, the new regions were overlapping but distinct.

 "Learning how the mind is organized is at the heart of the quest of understanding what makes us human.

The place-memory network provides a new framework for understanding the neural processes that drive memory-guided visual behaviors, including navigation," explains Robertson.

The research team is currently using virtual reality technology to explore how representations in the place-memory areas evolve as people become more familiar with new environments.

read the original unedited article at https://medicalxpress.com/news/2021-05-reveals-memories-familiar-brain.html

read the study paper "A network linking scene perception and spatial memory systems in posterior cerebral cortex"  at http://dx.doi.org/10.1038/s41467-021-22848-z

Neurological disorders such as Parkinson's disease and epilepsy have had some treatment success with deep brain stimulation, but those require surgical device implantation.

A multidisciplinary team at Washington University in St. Louis has developed a new brain stimulation technique using focused ultrasound that is able to turn specific types of neurons in the brain on and off and precisely control motor activity without surgical device implantation.

The team, led by Hong Chen, is the first to provide direct evidence showing noninvasive, cell-type-specific activation of neurons in the brain of mammal by combining ultrasound-induced heating effect and genetics, which they have named sonothermogenetics.

It is also the first work to show that the ultrasound- genetics combination can robustly control behavior by stimulating a specific target deep in the brain.

Results of the three years of research, which was funded in part by the National Institutes of Health's BRAIN Initiative, were published online in Brain Stimulation May 11, 2021.

"Our work provided evidence that sonothermogenetics evokes behavioral responses in freely moving mice while targeting a deep brain site," Chen said. "Sonothermogenetics has the potential to transform our approaches for neuroscience research and uncover new methods to understand and treat human brain disorders."

more at https://medicalxpress.com/news/2021-05-tool-deep-brain-neurons-combining.html

As researchers learn more about the brain, it has become clear that responsive neurostimulation is becoming increasingly effective at probing neural circuit function and treating neuropsychiatric disorders, such as epilepsy and Parkinson's disease. But current approaches to designing a fully implantable and biocompatible device able to make such interventions have major limitations: their resolution isn't high enough and most require large, bulky components that make implantation difficult with risk of complications.

A Columbia Engineering team led by Dion Khodagholy has come up with a new approach that shows great promise to improve such devices. Building on their earlier work to develop smaller, more efficient conformable bioelectronic transistors and materials, the researchers orchestrated their devices to create high performance implantable circuits that allow reading and manipulation of brain circuits.

Their multiplex-then-amplify (MTA) system requires only one amplifier per multiplexer, in contrast to current approaches that need an equal number of amplifiers as number of channels.

The team built the MTA device and then confirmed its functionality by developing a fully implantable, responsive embedded system that can acquire—in real time—individual neural action potentials using conformable conducting polymer-based electrodes. It can accomplish this with low-latency arbitrary waveform stimulation and local data storage—all within a miniaturized (approximately the size of a quarter) physical footprint.

Khodagholy collaborated on the study, published today by Proceedings of the National Academy of Sciences (PNAS), with Jennifer N. Gelinas, Department of Neurology and the Institute for Genomic Medicine at Columbia University Irving Medical Center.

read more at https://medicalxpress.com/news/2021-05-neuroelectronic-brain-circuits.html