Researchers Introduce New Brain Mapping Model Which Could Improve Effectiveness of Transcranial Magnetic Stimulation

Brain researchers from the Perelman School of Medicine at the University of Pennsylvania have developed a new brain mapping model which could improve the success rate of transcranial magnetic stimulation (TMS) in treating conditions including depression, neuropathic pain, and stroke. The model helps pinpoint target sites during TMS, a procedure that uses magnetic fields to stimulate nerve cells in the brain to alleviate or eliminate symptoms of stroke, depression, and attention disorders. The new model was presented at the 67th American Academy of Neurology Annual Meeting in Washington, D.C. on Wednesday, April 22.

During TMS, a large electromagnetic coil is placed on the scalp near the forehead. The device creates electric currents that rouse nerve cells in the cerebrum, the part of the brain involved in thinking, perceiving, planning, and understanding language. Through this arousal, improvements in the underlying condition have been achieved. But the technique hasn’t worked for everyone.

“We know that certain genotypes reduce TMS efficacy, but aside from that we really don’t understand why TMS works for some and not for others,” said lead researcher John D. Medaglia, PhD, a postdoctoral fellow at Penn’s Laboratory for Cognition and Neural Stimulation. “Our goal is to better understand how to appropriately model and target the neural system so that we can know with certainty whether the treatment will succeed.”

“Advances in neuroscience have increasingly shown the importance of understanding brains as complex and changing networks,” said Medaglia. “In this light, the use of TMS to date has not been optimal because of the relative absence of clear scientific principles for understanding how TMS affects network operations in the brain.”

Medaglia says that the challenge is to identify the best possible location for placing the coil in order to generate good results. “We use a model borrowed from engineering called network control theory to suggest how information about the brain’s structures and connections that can be obtained from imaging studies can be used to better understand and enhance the effects of TMS on brain networks,” he said “This new way of thinking about brain networks and how they are controlled could lead to better informed, neuroscience-driven TMS therapies that optimize the effects of TMS on brain activity.”

The Penn model emphasizes precision in placement as a precursor to enhanced results. It utilizes 3-D brain data inspired by the Human Connectome Project to make informed inferences about optimal placement of the coil during treatment. The Human Connectome Project is an NIH-supported initiative which includes 3-D scanning of the brains of 1,200 healthy adult subjects over a three-year span (2012 to 2015). The goal is to map the connections between neural pathways (“white matter”) that link different regions of grey matter to each another. Regions of the brain need to communicate via white matter in order to carry out behavior involved in daily life.

“Placing the coil even millimeters or centimeters away from the optimal location could result in the treatment being partially or completely ineffective,” says Medaglia. “Our model relies on extensive knowledge of brain neuron interconnections to guide clinicians in best situating the electromagnetic coil.”

Medaglia and his colleagues focused on white matter connecting regions of the brain important for routine behavior, time-consuming behavior, and challenging mental activity. Pinpointing the most visibly robust or favorably connected (depending on the circumstances) neural connections for these areas enabled the investigators to develop a model for predicting placement locations that would likely increase beneficial TMS effects on patients with specific afflictions arising from these locations in the brain.

The Penn team plan to begin testing the model in the coming months. “We will be looking to see if patients treated under it fare better after TMS than those treated under current approaches,” Medaglia said.

Magnetic fields frozen into meteorite grains tell a shocking tale of solar system birth

The most accurate laboratory measurements yet made of magnetic fields trapped in grains within a primitive meteorite are providing important clues to how the early solar system evolved. The measurements point to shock waves traveling through the cloud of dusty gas around the newborn Sun as a major factor in solar system formation.

The results appear in a paper published Nov. 13 in the journal Science. The lead author is graduate student Roger Fu of MIT, working under Benjamin Weiss; Steve Desch of Arizona State University’s School of Earth and Space Exploration is a co-author of the paper.

“The measurements made by Fu and Weiss are astounding and unprecedented,” says Desch. “Not only have they measured tiny magnetic fields thousands of times weaker than a compass feels, they have mapped the magnetic fields’ variation recorded by the meteorite, millimeter by millimeter.”

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(Image caption: This functional magnetic resonance imaging map shows a center periphery connectivity mass in the primary visual cortex (V1) of the congenitally blind brain. Credit: Ella Striem-Amit and Amir Amedi)

New study challenges conventional wisdom that sight-based brain sensory network organization is impaired with blindness

Is visual input essential to how the topographical map of the visual cortex develops in the human brain?

In new research published today, scientists at the Hebrew University of Jerusalem and in Germany and the USA show that the way in which the brain organizes its visual sense remains intact even in people who are blind from birth, and that at least the pattern of functional connectivity between the visual area and the topographical representation of space (up/down, left/right, etc.) can develop on its own without any actual visual experience.

The findings, reported in the prestigious peer-reviewed neuroscience journal Brain, dispel the nearly half-century belief that the visual cortex — the area of the brain concerned with the sense of sight — completely fails to develop properly in people who are blind at birth, suggesting it might not be completely correct.

“Though the ‘blind brain’ wiring may change greatly in the blind in its frontal language related parts, it still retains the most fundamental topographical and functional connectivity organizational principles of the visual cortex, known as 'retinotopic mapping’ — the processing of two-dimensional visual images through the eye,” said co-lead researcher Amir Amedi, associate professor of medical neurobiology at the Hebrew University’s Edmond and Lily Safra Center for Brain Sciences and IMRIC, the Institute for Medical Research Israel-Canada.

Operating within the Hebrew University’s Faculty of Medicine, IMRIC coordinates research within the departmental areas of medical neurobiology, molecular genetics and biology, immunology and cancer research.

The researchers found that the same “mapping” divisions-of-labor present in the normally sighted brain are also present in the brains of people born blind as reflected from their resting state connectivity patterns. This fundamental organization of the visual cortex was even found in people whose eyes did not develop normally, suggesting normal eye development may not be necessary for the establishment of large-scale functional connectivity network mapping in the most fundamental visual areas like V1, the primary visual cortex.

Contrary to conventional wisdom, the latest findings reported by Prof. Amir Amedi, Dr. Ella Striem-Amit and Smadar Ovadia-Caro suggest that some key features and properties of visual cortex organization do not require visual experience to progress. The study further adds that the brain’s visual cortex does not lose all of its properties even when completely deprived of vision.

“Some of the brain’s connectivity maps is hardwired, possibly dependent on genetically-driven processes that do not need any external sensory information for their activation, while other process might indeed need visual input to specialize” Amedi said. The visual brain resting-state connectivity networks separated to up vs. down, right vs. left, front vs. back are also present in the brain of those born blind, according the study.

Previous research by neurophysiologists David Hubel and Torsten Wiesel, which earned them a Nobel Prize in 1981, suggested that sight restoration could not be attempted on people blind from birth. Therefore, they surmised, the blinded cortex could not enable the blind-from-birth to have sight.

According to Hebrew University’s Amedi, this latest research, combined with other research conducted in the Amedi Lab for Multisensory Research, “means that it may be possible to successfully teach blind people to 'see with sounds and touch.’” Using tools of sensory substitution, it may be possible to aid people born blind (or late blind) in a variety of new ways in the future, including restoring high-order functional pattern recognition for objects, localization, shape and even numbers and text, as previously reported in the prestigious journal Nature Communications (Abboud et al., Nature Comm., 2015). Any blind person can download and train themselves  on using such technologies for free via the following link:

Earth’s magnetic heartbeat
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ESA - SWARM Mission logo.

10 May 2016

With more than two years of measurements by ESA’s Swarm satellite trio, changes in the strength of Earth’s magnetic field are being mapped in detail.

Launched at the end of 2013, Swarm is measuring and untangling the different magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere – an undertaking that will take several years to complete.

Changes in strength of Earth’s magnetic field
Although invisible, the magnetic field and electric currents in and around Earth generate complex forces that have immeasurable effects on our everyday lives.

The field can be thought of as a huge bubble, protecting us from cosmic radiation and electrically charged atomic particles that bombard Earth in solar winds. However, it is in a permanent state of flux.

Presented at this week’s Living Planet Symposium, new results from the constellation of Swarm satellites show where our protective field is weakening and strengthening, and importantly how fast these changes are taking place.

The animation above shows the strength of Earth’s magnetic field and how it changed between 1999 and May 2016.

Blue depicts where the field is weak and red shows regions where it is strong. As well as recent data from the Swarm constellation, information from the CHAMP and Ørsted satellites were also used to create the map.

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The force that protects our planet
It shows clearly that the field has weakened by about 3.5% at high latitudes over North America, while it has strengthened about 2% over Asia. The region where the field is at its weakest – the South Atlantic Anomaly – has moved steadily westward and weakened further by about 2%.

In addition, the magnetic north pole is wandering east, towards Asia.

The second animation shows the rate of change in Earth’s magnetic field between 2000 and 2015. Regions where changes in the field slowed are shown in blue while red shows where changes speeded up.

For example, changes in the field have slowed near South Africa, but have changed faster over Asia.

The magnetic field is thought to be produced largely by an ocean of molten, swirling liquid iron that makes up our planet’s outer core, 3000 km under our feet. Acting like the spinning conductor in a bicycle dynamo, it generates electrical currents and thus the continuously changing electromagnetic field.

It is thought that accelerations in field strength are related to changes in how this liquid iron flows and oscillates in the outer core.

Swarm shows rate of change
Chris Finlay, senior scientist at DTU Space in Denmark, said, “Swarm data are now enabling us to map detailed changes in Earth’s magnetic field, not just at Earth’s surface but also down at the edge of its source region in the core.

“Unexpectedly, we are finding rapid localised field changes that seem to be a result of accelerations of liquid metal flowing within the core.”

Rune Floberghagen, ESA’s Swarm mission manager, added, “Two and a half years after the mission was launched it is great to see that Swarm is mapping the magnetic field and its variations with phenomenal precision.

“The quality of the data is truly excellent, and this paves the way for a profusion of scientific applications as the data continue to be exploited.”

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Swarm constellation
It is clear that ESA’s innovative Swarm mission is providing new insights into our changing magnetic field. Further results are expected to lead to new information on many natural processes, from those occurring deep inside the planet to weather in space caused by solar activity.

In turn, this information will certainly yield a better understanding of why the magnetic field is weakening in some places, and globally.

Related links:

Living Planet 2016:

Swarm / Earth Explorers / The Living Planet Programme:

ESA’s magnetic field mission Swarm:

Images, Videos, Text, Credits: ESA/ATG medialab/DTU Space.

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