Neurons See What We Tell Them to See

Neurons programmed to fire at specific faces—such as the famously reported “Jennifer Aniston neuron”—may be more in line with the conscious recognition of faces than the actual images seen. Subjects presented with a blended face, such as an amalgamation of Bill Clinton and George W. Bush, had significantly more firing of such face-specific neurons when they recognized the blended or morphed face as one person or the other. Results of the study led by Christof Koch at the Allen Institute for Brain Science, and carried out by neuroscientists Rodrigo Quian Quiroga at the University of Leicester, Alexander Kraskov at University College London and Florian Mormann at the University of Bonn, under the clinical supervision of the neurosurgeon Itzhak Fried at the University of California at Los Angeles Medical School, are published online today in the journal Neuron.

Some neurons in the region of the brain known as the medial temporal lobe are observed to be extremely selective in the stimuli to which they respond. A cell may only fire in response to different pictures of a particular person who is very familiar to the subject (such as loved one or a celebrity), the person’s written or spoken name, or simply recalling the person from memory.

“These highly specific cells are an entry point to investigate how the brain makes meaning out of visual information,” explains Christof Koch, Chief Scientific Officer at the Allen Institute for Brain Science and senior author on the paper. “We wanted to know how these cells responded not just to a simple image of a person’s face, but to a more ambiguous image of that face averaged or morphed with another person’s face.”

For the trials, subjects were shown either the face of individuals such as Bill Clinton or George W. Bush (the “adaptor” image), and then an ambiguous face which was a blend of both faces. Primed with the Clinton image, subjects tended to recognize Bush’s face in the blended image, while subjects who saw Bush’s face first recognized the blended face as Clinton. That is, even though the blended images were identical, subjects tended to consciously perceive the identity of face to which they were not adapted.

Researchers wanted to know whether these selective neurons responded to the actual image on the screen, or whether they responded more to the perception that the image caused in the brain of the subject. When subjects recognized the ambiguous face as belonging to Clinton, their Clinton-specific neurons fired. However, when subjects recognized that same face as Bush, the neurons fired significantly less. These results indicated that conscious recognition of the face played a crucial role in whether the neurons fired, rather than the raw visual stimulus.

“This study provides further evidence that stimulus-specific neurons in the medial temporal lobe follow the subjective perception of the person, as opposed to faithfully reporting the visual stimulus the person sees,” explains Koch. “This distinction may help us glean insight into how the brain takes raw visual information and transforms it into something meaningful, which can be further modulated by other aspects of experience in the brain.”

Infant brains imply adult ills: Researchers study traits in babies as young as two weeks

Brain images from newborns are giving scientists a glimpse of the future - not just into the lives of their tiny subjects but also paths to treatment for adult patients with schizophrenia and Alzheimer’s disease.

Researchers from the University of North Carolina-Chapel Hill found degeneration in the brains of 2-week-old infants, a result considered a “game changer” for the field of brain research, said Jay Giedd, a brain imaging specialist for the National Institute of Mental Health.

"Our original model was that the brain was fine until someone got the illness," Giedd said. "This work shows that these changes are there probably from conception. It also suggests that while these traits don’t cause brain damage, they set up the brain to be slightly different."

The researchers examined scans of 272 newborns. About 15 percent were found to have smaller medial temporal lobe sections. “The medial temporal lobe plays an important role in memory,” said Rebecca Knickmeyer, a UNC assistant professor of psychiatry and co-author of the research, published last month in Cerebral Cortex, an online journal.

"The idea is that this is an anatomical vulnerability. If you start out with less, you might hit active symptoms earlier in life."

The researchers also found specific gene traits associated with Alzheimer’s in babies with the smaller media temporal lobes.

"We were interested because it was generally known that people’s genes contribute to psychiatric conditions later in life, but pretty much all the existing studies were in adults," Knickmeyer said. "Our question was ‘When were these genes exerting their effect?’ Now we know it’s much earlier than previously thought, perhaps before birth."

Research such as this would benefit from the Brain Activity Map under development through the National Institutes of Health. The project’s 10-year goal is to create a map of the brain’s nearly 30,000 genes as well as the circuitry system that transmits information via brain waves.

President Obama mentioned the project in his State of the Union address and is expected to include funding for the project in the upcoming federal budget. Foundations and some private companies have also expressed interest in assisting in the project, which is expected to push brain research to a higher level.

"As brain scientists, we were giddy to hear this," Giedd said. "Motivation is sky high. If they fund this, we believe our work will really take off." Giedd, who is familiar with but did not participate in the infant brain study, said the search for treatments or cures for diseases such as Alzheimer’s, autism, schizophrenia and Parkinson’s disease have been stymied by the many mysteries that remain regarding how the brain functions.

"If we understood more about the mechanisms that cause these diseases, we could step in and do something about it," Giedd said. "The brain is so complicated. Most diseases don’t just involve one or two or even three genes. It might be 60 or 100 genes, along with upbringing, diet and environment. There are so many parameters to the equation."

Knickmeyer said her research team plans to follow up with the newborns as they grow into adulthood to see whether the traits displayed by infants change over time or remain stable throughout their lives.

Daniel Kaufer, cognitive neurology and memory disorders chief for UNC’s Department of Neurology, said he thinks the time is right for great advances in brain research.

"We are at the crossroads of two important events: the realization that brain disorders may occur long before symptoms begin, and the development of brain imaging technology to record brain processes," Kaufer said.

Learning more about the brain’s functions through gene mapping may be the third piece of the puzzle. “Right now, there is no map of the human brain,” said Murali Doraiswamy, professor of psychiatry and behavioral sciences at Duke University School of Medicine.

Doraiswamy said the brain carries thousands of genes that influence thought, perception, emotion, memory and other mental activities. “We want to find out how much is nature and how much is nurture,” he added. “I think we are at the forefront of something very insightful, but also a little frightening.”

MAPPING A NEW WORLD

The Brain Activity Map is being planned as a decade-long research effort to create a comprehensive outline of the structure of the human brain and its neurons.

Funding is expected to come from a variety of sources, including the federal government, private industry and research foundations.

Details of the project have not yet been made public. But it is being compared to the DNA sequencing effort known as the Human Genome Project, which ran from 1990 to 2003 and cost $3.8 billion.

In-brain monitoring shows memory network

Working with patients with electrodes implanted in their brains, researchers at the University of California, Davis, and The University of Texas Health Science Center at Houston (UTHealth) have shown for the first time that areas of the brain work together at the same time to recall memories. The unique approach promises new insights into how we remember details of time and place.

"Previous work has focused on one region of the brain at a time," said Arne Ekstrom, assistant professor at the UC Davis Center for Neuroscience. "Our results show that memory recall involves simultaneous activity across brain regions." Ekstrom is senior author of a paper describing the work published Jan. 27 in the journal Nature Neuroscience.

Ekstrom and UC Davis graduate student Andrew Watrous worked with patients being treated for a severe seizure condition by neurosurgeon Dr. Nitin Tandon and his UTHealth colleagues.

To pinpoint the origin of the seizures in these patients, Tandon and his team place electrodes on the patient’s brain inside the skull. The electrodes remain in place for one to two weeks for monitoring.

Six such patients volunteered for Ekstrom and Watrous’ study while the electrodes were in place. Using a laptop computer, the patients learned to navigate a route through a virtual streetscape, picking up passengers and taking them to specific places. Later, they were asked to recall the routes from memory.

Correct memory recall was associated with increased activity across multiple connected brain regions at the same time, Ekstrom said, rather than activity in one region followed by another.

However, the analysis did show that the medial temporal lobe is an important hub of the memory network, confirming earlier studies, he said.

Intriguingly, memories of time and of place were associated with different frequencies of brain activity across the network. For example, recalling, “What shop is next to the donut shop?” set off a different frequency of activity from recalling “Where was I at 11 a.m.?”

Using different frequencies could explain how the brain codes and recalls elements of past events such as time and location at the same time, Ekstrom said.

"Just as cell phones and wireless devices work at different radio frequencies for different information, the brain resonates at different frequencies for spatial and temporal information," he said.

The researchers hope to explore further how the brain codes information in future work.

The neuroscientists analyzed their results with graph theory, a new technique that is being used for studying networks, ranging from social media connections to airline schedules.

"Previously, we didn’t have enough data from different brain regions to use graph theory. This combination of multiple readings during memory retrieval and graph theory is unique," Ekstrom said.

Placing electrodes inside the skull provides clearer resolution of electrical signals than external electrodes, making the data invaluable for the study of cognitive functions, Tandon said. “This work has yielded important insights into the normal mechanisms underpinning recall, and provides us with a framework for the study of memory dysfunction in the future.”