Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MRI technique lets researchers directly compare similarities, differences between monkey and human brain

22.10.2002


James Todd


Researchers have developed a new way to use a decade-old imaging method to directly compare the brains of monkeys with those of humans. Their report appeared in the journal Science.

The method uses functional Magnetic Resonance Imaging (fMRI) – a technique that measures blood volume and flow and blood-oxygen levels in the brain. It also provides an indirect measure of neuronal activity in different regions of the brain.

Neurons need oxygen and glucose to work. Blood carries both substances, and both can cross the blood-brain barrier. When a particular region of the brain is activated, the blood flow to that area temporarily increases in order to supply the neurons with fresh oxygen and glucose.



“What we’re doing is an indirect measurement of the human brain’s electrical activity,” said Wim Vanduffel, the report’s lead author and an instructor at the Athinoula A. Martinos Center for Biomedical Imaging in Charlestown, Mass.

“It’s the best way at present for investigating patterns of neural activity in humans,” he said.

The researchers used the same fMRI technique on humans and on monkeys to compare activity in an area of the brain called the visual cortex, the region that processes vision and motion. While each species shares similar traits in the visual cortex, the researchers did find distinct differences between the species in two key areas.

“Implicit in the neuroscience community was that the monkey cortex is a good model for the human cortex,” said James Todd, a study co-author and a professor of psychology at Ohio State University. “Scientists didn’t have any choice but to make that assumption, as the monkey brain was the only model we had to work with.”

What set the fMRI technique used in this study apart from past fMRI experiments on monkeys is that the monkeys remained conscious during the experiments.

“Until this point, anybody who has used fMRI on monkeys did so while the animals were sedated,” Todd said. “That presents a real problem since sedation may alter the patterns of neural activity that occur when monkeys are awake.”

Eleven human subjects each participated in 14 separate fMRI scan sessions, and three juvenile macaques participated in at least eight sessions. While each session produced data, some of the sessions produced weak signals. Therefore, the researchers averaged together the sessions in order to obtain reliable results.

The experiments were conducted in a laboratory run by Guy Orban, head of the division of neurophysiolgy at Katholieke Universiteit Leuven in Belgium, where Wim Vanduffel also holds a postdoctoral position. Todd was responsible for designing the images viewed by all of the subjects.

For each session, a human subject lay on his back inside the fMRI and watched as nine randomly connected lines began to rotate on a monitor inside the machine. This procedure could not be used on the monkeys, however, because monkeys don’t like lying on their backs. Instead, the researchers used juvenile monkeys that could be seated within the fMRI apparatus.

The researchers looked for areas of the visual cortex that were activated while the subjects watched rotating 3-D images. Each portion of a subject’s visual cortex was scanned during each session in the fMRI. In order to better see the areas of activity in the monkey brain, the macaques were injected with a solution that enhanced the contrast shown in the final scans.

“For unknown reasons, the fMRI signals from the monkeys were weaker than those from the humans,” Orban said. “Since the monkey brain is smaller, we needed to use a contrasting agent to increase the fMRI’s ability to pick up a signal.”

While a regular MRI measures tissue density and structure, fMRI measures the flow, volume and oxygenation of blood in tissue. In the current study, this technique was used to investigate regions of the brain that were activated when the subjects looked at the moving 3-D images.

“The advantage of functional MRI is that scientists can see which regions of the brain are active,” Orban said.

The results showed pronounced differences between the two species: in an area of the human visual cortex called V3A – an area thought to be responsible for a variety of visual functions, such as motion processing and stereoscopic depth – and also in the intraparietal cortex. The researchers noted that, in humans, four distinct areas of the intraparietal cortex were involved in processing the rotating 3-D images. There is no clear counterpart to this region in monkeys.

“The results suggest that, as humans evolved, some portions of their brains adapted to produce specific abilities, such as controlling fine motor skills,” Orban said.

The results don’t mean that monkeys don’t have 3-D visual capabilities. The findings do show that researchers now have a technique enabling them to make reliable comparisons between a monkey brain and a human brain.

“This study provides the first evidence of a functional difference between the human and the monkey brain,” Todd said. “The results show that, in at least one important aspect, the brains function quite differently.”

“We were in a paradoxical situation before we had these results,” Orban said. “On one hand, it’s obvious that humans and monkeys are different.

“On the other hand, when we use the physiology of the monkey brain as a model to explain what we see in a human functional MRI scan, we had assumed that the activity was occurring in the same region in each brain. We had to make an assumption, which we knew would be wrong from time to time. We just didn’t know when that assumption would be wrong.”

“Now we have a way to verify when the monkey model does not apply and when it really can apply,” Orban said. “And we can be much more precise in extrapolating findings from monkeys to humans.”

Support for this research came from the Inter-University Attraction Poles (a Belgian research foundation); GOA (a regional research support foundation in Belgium); the Fund for Scientific Research - Flanders (FWO-Flanders); and the Queen Elisabeth Medical Foundation.

Todd, Orban and Vanduffel conducted the study with Denis Fize, Hendrik Peuskens, Katrien Denys and Stefan Sunaert, all of Katholieke Universiteit Leuven.


Contact: James Todd, 614-292-8661; Todd.44@osu.edu
Guy Orban, 011 +32 16 345744; Guy.Orban@Med.Kuleuven.Ac.Be
Wim Vanduffel, 617-726-0318; wim@nmr.mgh.harvard.edu

Written by Holly Wagner, 614-292-8310; Wagner.235@osu.edu

James Todd | EurekAlert!
Further information:
http://www.fmrib.ox.ac.uk/fmri_intro/
http://www.nmr.mgh.harvard.edu/index.html
http://www.cog.ohio-state.edu/people/cfaculty/todd.html

More articles from Life Sciences:

nachricht Chains of nanogold – forged with atomic precision
23.09.2016 | Suomen Akatemia (Academy of Finland)

nachricht Self-assembled nanostructures hit their target
23.09.2016 | King Abdullah University of Science and Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Chains of nanogold – forged with atomic precision

23.09.2016 | Life Sciences

New leukemia treatment offers hope

23.09.2016 | Health and Medicine

Self-assembled nanostructures hit their target

23.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>