By tracking brain activity when an animal stops to look around its environment, neuroscientists at the Johns Hopkins University believe they can mark the birth of a memory.
Using lab rats on a circular track, James Knierim, professor of neuroscience in the Zanvyl Krieger Mind/Brain Institute at Johns Hopkins, and a team of brain scientists noticed that the rats frequently paused to inspect their environment with head movements as they ran. The scientists found that this behavior activated a place cell in their brain, which helps the animal construct a cognitive map, a pattern of activity in the brain that reflects the animal’s internal representation of its environment.
In a paper recently published in the journal Nature Neuroscience, the researchers state that when the rodents passed that same area of the track seconds later, place cells fired again, a neural acknowledgement that the moment has imprinted itself in the brain’s cognitive map in the hippocampus.
The hippocampus is the brain’s warehouse for long- and short-term processing of episodic memories, such as memories of a specific experience like a trip to Maine or a recent dinner. What no one knew was what happens in the hippocampus the moment an experience imprints itself as a memory.
“This is like seeing the brain form memory traces in real time,” said Knierim, senior author of the research. “Seeing for the first time the brain creating a spatial firing field tied to a specific behavioral experience suggests that the map can be updated rapidly and robustly to lay down a memory of that experience.”
A place cell is a type of neuron within the hippocampus that becomes active when an animal or human enters a particular place in its environment. The activation of the cells helps create a spatial framework much like a map, that allows humans and animals to know where they are in any given location. Place cells can also act like neural flags that “mark” an experience on the map, like a pin that you drop on Google maps to mark the location of a restaurant.
“We believe that the spatial coordinates of the map are delivered to the hippocampus by one brain pathway, and the information about the things that populate the map, like the restaurant, are delivered by a separate pathway,” Knierim said. “When you experience a new item in the environment, the hippocampus combines these inputs to create a new spatial marker of that experience.”
In the experiments, researchers placed tiny wires in the brains of the rats to monitor when and where brain activity increased as they moved along the track in search of chocolate rewards. About every seven seconds, the rats stopped moving forward and turned their heads to the perimeter of the room as they investigated the different landmarks, behavior called “head-scanning.”
“We found that many cells that were previously silent would suddenly start firing during a specific head-scanning event,” Knierim said. “On the very next lap around the track, many of these cells had a brand new place field at that exact same location and this place field remained usually for the rest of the laps. We believe that this new place field marks the site of the head scan and allows the brain to form a memory of what it was that the rat experienced during the head scan.”
Knierim said the formation and stability of place fields and the newly activated place cells requires further study. The research is primarily intended to understand how memories are formed and retrieved under normal circumstances, but it could be applicable to learning more about people with brain trauma or hippocampal damage due to aging or Alzheimer’s.
“There are strong indications that humans and rats share the same spatial mapping functions of the hippocampus, and that these maps are intimately related to how we organize and store our memories of prior life events,” Knierim said. “Since the hippocampus and surrounding brain areas are the first parts of the brain affected in Alzheimer’s, we think that these studies may lend some insight into the severe memory loss that characterizes the early stages of this disease.”
Researchers discover that an important clue to diagnosing Parkinson’s disease may lie just beneath the skin.
Although Parkinson’s disease is the second most prevalent neurodegenerative disorder in the U.S., there are no standard clinical tests available to identify this widespread condition. As a result, Parkinson’s disease often goes unrecognized until late in its progression, when the brain’s affected neurons have already been destroyed and telltale motor symptoms such as tremor and rigidity have already appeared.
Now researchers from Beth Israel Deaconess Medical Center (BIDMC) have discovered that an important clue to diagnosing Parkinson’s may lie just beneath the skin.
In a study scheduled to appear in the October 29 print issue of the journal Neurology and currently published on-line, the investigators report that elevated levels of a protein called alpha-synuclein can be detected in the skin of Parkinson’s patients, findings that offer a possible biomarker to enable clinicians to identify and diagnose PD before the disease has reached an advanced stage.
Parkinson’s disease affects more than 1 million individuals throughout the U.S. Diagnosis is currently made through neurological history and examination, often by a patient’s primary care physician.
“Even the experts are wrong in diagnosing Parkinson’s disease a large percentage of the time,” says senior author Roy Freeman, MD, Director of the Autonomic and Peripheral Nerve Laboratory at BIDMC and Professor of Neurology at Harvard Medical School. “A reliable biomarker could help doctors in more accurately diagnosing Parkinson’s disease at an earlier stage and thereby offer patients therapies before the disease has progressed.”
Alpha-synuclein is a protein found throughout the nervous system. Although its function is unknown, it is the primary component of protein clumps known as Lewy bodies, which are considered the hallmark of Parkinson’s disease. There is accumulating evidence that the protein plays a role in Parkinson’s disease development.
“Alpha-synuclein deposition occurs early in the course of Parkinson’s disease and precedes the onset of clinical symptoms,” explains Freeman, who with his coauthors suspected that the protein was elevated in the skin’s structures with autonomic innervation.
“Symptoms related to the autonomic nervous system, including changes in bowel function, temperature regulation, and blood pressure control may antedate motor symptoms in Parkinson’s patients,” he explains. “Skin-related autonomic manifestations, including excessive and diminished sweating and changes in skin color and temperature, occur in almost two-thirds of patients with Parkinson’s disease. The skin can provide an accessible window to the nervous system and based on these clinical observations, we decided to test whether examination of the nerves in a skin biopsy could be used to identify a PD biomarker.”
To test this hypothesis, the research team enrolled 20 patients with Parkinson’s disease and 14 control subjects of similar age and gender. The participants underwent examinations, autonomic testing and skin biopsies in three locations on the leg. Alpha-synuclein deposition and density of cutaneous sensory, sudomotor and pilomotor nerve fibers were measured.
As predicted, their results showed that alpha-synuclein was increased in the cutaneous nerves supplying the sweat glands and pilomotor muscles in the Parkinson’s patients. Higher alpha-synuclein deposition in the nerves supplying the skin’s autonomic structures was associated with more advanced Parkinson’s disease and worsening autonomic function.
“There is a strong and unmet need for a biomarker for Parkinson’s disease,” says Freeman. “Alpha-synuclein deposition within the skin has the potential to provide a safe, accessible and repeatable biomarker. Our next steps will be to test whether this protein is present in the cutaneous nerves of individuals at risk for Parkinson’s disease, and whether measurement of alpha-synuclein deposition in the skin can differentiate Parkinson’s disease from other neurodegenerative disorders.”
Study coauthors include BIDMC investigators Ningshan Wang, PhD and Christopher Gibbons, MD (co-first authors) and Jacob Lafo.
This study was supported by National Institutes of Health grant K23NS020509 and grants from the Langer Family Foundation and the RJG Foundation.
Researchers at UT Southwestern Medical Center have identified a cellular switch that potentially can be turned off and on to slow down, and eventually inhibit the growth of the most commonly diagnosed and aggressive malignant brain tumor.
Findings of their investigation show that the protein RIP1 acts as a mediator of brain tumor cell survival, either protecting or destroying cells. Researchers believe that the protein, found in most glioblastomas, can be targeted to develop a drug treatment for these highly malignant brain tumors. The study was published online Aug. 22 inCell Reports.
“Our study identifies a new mechanism involving RIP1 that regulates cell division and death in glioblastomas,” said senior author Dr. Amyn Habib, associate professor of neurology and neurotherapeutics at UT Southwestern, and staff neurologist at VA North Texas Health Care System. “For individuals with glioblastomas, this finding identified a target for the development of a drug treatment option that currently does not exist.”
In the study, researchers used animal models to examine the interactions of the cell receptor EGFRvIII and RIP1. Both are used to activate NFκB, a family of proteins that is important to the growth of cancerous tumor cells. When RIP1 is switched off in the experimental model, NFκB and the signaling that promotes tumor growth is also inhibited. Furthermore, the findings show that RIP1 can be activated to divert cancer cells into a death mode so that they self-destruct.
According to the American Cancer Society, about 30 percent of brain tumors are gliomas, a fast-growing, treatment-resistant type of tumor that includes glioblastomas, astrocytomas, oligodendrogliomas, and ependymomas. In many cases, survival is tied to novel clinical trial treatments and research that will lead to drug development.
The Department of Neurology and Neurotherapeutics at UT Southwestern is ranked in the top 20 in the nation, according to U.S. News & World Report. UT Southwestern physicians routinely deal with the most difficult neurology cases referred from around the region, state, and nation.
The research was conducted with support from the National Institutes of Health, NASA, and the Cancer Prevention and Research Institute of Texas.
UT Southwestern investigators who participated in the study include former postdoctoral researcher Dr. Vineshkumar Puliyappadamba, senior research associate Dr. Sharmistha Chakraborty, former research assistant Sandili Chauncey, and senior research scientist Dr. Li Li, all from the Department of Neurology and Neurotherapeutics. Dr. Kimmo Hatanpaa, associate professor of pathology; Dr. Bruce Mickey, director of the Annette G. Strauss Center in Neuro-Oncology; Dr. David Boothman, professor of radiation oncology and pharmacology in the Harold C. Simmons Comprehensive Cancer Center; and Dr. Sandeep Burma, associate professor of radiation oncology, also contributed to the research.
Scientists at Albert Einstein College of Medicine of Yeshiva University have shown that high-functioning autism spectrum disorder (ASD) children appear to outgrow a critical social communication disability. Younger children with ASD have trouble integrating the auditory and visual cues associated with speech, but the researchers found that the problem clears up in adolescence. The study was published today in the online edition of the journal Cerebral Cortex.
“This is an extremely hopeful finding,” said lead author John Foxe, Ph.D., professor of pediatrics and in the Dominick P. Purpura Department of Neuroscience, as well as director of research of the Children’s Evaluation and Rehabilitation Center at Einstein. “It suggests that the neurophysiological circuits for speech in these children aren’t fundamentally broken and that we might be able to do something to help them recover sooner.”
According to Dr. Foxe, the ability to integrate “heard” and “seen” speech signals is crucial to effective communication. “Children who don’t appropriately develop this capacity have trouble navigating educational and social settings,” he said.
In a previous study, Dr. Foxe and his colleagues demonstrated that children with ASD integrate multisensory information such as sound, touch and vision differently from typically developing children. Among typically developing children, multisensory integration (MSI) abilities were known to continue improving late into childhood. The current study looked at whether one aspect of MSI — integrating audio and visual speech signals — continues to develop in high-functioning children with ASD as well.
In the study, 222 children ages 5 to 17, including both typically developing children and high-functioning children with ASD, were tested for how well they could understand speech with increasing levels of background noise. In one test, the researchers played audio recordings of simple words. In a second test, the researchers played a video of the speaker articulating the words, but no audio. A third test presented the children with both the audio and video recordings.
The test mimics the so-called “cocktail party” effect: a noisy environment with many different people talking. In such settings, people naturally rely on both auditory and facial clues to understand what another person is saying. “You get a surprisingly big boost out of lip-reading, compared with hearing alone,” said Dr. Foxe. “It’s an integrative process.”
In the first test (audio alone), the children with ASD performed almost as well as typically developing children across all age groups and all background noise levels. In the second test (video alone), the children with ASD performed significantly worse than the typically developing children across all age groups and all background noise levels. “But the typically developing children didn’t perform very well, either,” said Dr. Foxe. “Most people are fairly terrible at lip-reading.”
In the third test (audio and video), the younger children with ASD, ages 6 to 12, performed much worse than the typically developing children of the same age, particularly at higher levels of background noise. However, among the older children, there was no difference in performance between the typically developing and children with ASD.
“In adolescence, something amazing happens and the kids with ASD begin to perform like the typically developing kids,” said Dr. Foxe. “At this point, we can’t explain why. It may be a function of a physiological change in their brain or of interventions they’ve received, or both. That is something we need to explore.”
The researchers acknowledge some limitations to their study. “Instead of doing a cross-sectional study like this, where we tested children at various ages, we would prefer to do a longitudinal study that would involve the same kids who’d be followed over the years from childhood through adolescence,” Dr. Foxe said. “We also need to find a way to study what is happening with low- and mid-functioning children with ASD. They are much less tolerant of testing and thus harder to study.”
According to the researchers, the work highlights the need to develop more effective therapies to help ASD children better integrate audio and visual speech signals. “We are beginning to work on that,” said Dr. Foxe.
The paper is titled “Severe Multisensory Speech Integration Deficits in High-Functioning School-Aged Children with an Autism Spectrum Disorder (ASD) and their Resolution during Early Adolescence.” Other Einstein contributors are Sophie Molholm, Ph.D., Victor Del Bene, Daniella Blanco, Hans-Peter Frey and Lars Ross, Ph.D. Additional coauthors are Natalie Russo, Ph.D., at Syracuse University (Syracuse, NY) and Dave Saint-Amour at Université du Québec à Montréal (Montreal, Canada).
This study was primarily supported by a grant from the National Institute of Mental Health (MH085322), part of the National Institutes of Health. Pilot support was provided by Cure Autism Now, the Wallace Research Foundation, Fondation du Quebec de Recherche sur la Societe et la Culture, and the Canadian Institute of Health Research.
Now you’ve moved your eyes away from the above image let’s get to the nitty-gritty! I have to admit a curvaceous woman with beautiful big breasts is always a delight and I know I am not alone. But what is the fascination with those big, bulbous bags of fat drooping from women’s chests?
Scientists have never satisfactorily explained men’s curious breast fixation, but now, a neuroscientist has struck upon an explanation that he says “just makes a lot of sense.”
Larry Young, a professor of psychiatry at Emory University who studies the neurological basis of complex social behaviors, believes human evolution has harnessed an ancient neural circuit that originally evolved to strengthen the mother-infant bond during breast-feeding, and now uses this brain circuitry to strengthen the bond between couples as well. The result? Men, like babies, love breasts.
The mechanics of it are as such; when a woman’s nipples are stimulated during breast-feeding, the neurochemical oxytocin, otherwise known as the “love drug,” floods her brain, helping to focus her attention and affection on her baby. But research over the past few years has shown that in humans, this circuitry isn’t reserved for exclusive use by infants.
Recent studies [why was I not invited to these?] have found that nipple stimulation enhances sexual arousal in the great majority of women, and it activates the same brain areas as vaginal and clitoral stimulation. When a sexual partner touches, massages or nibbles a woman’s breasts, this triggers the release of oxytocin in the woman’s brain, in the same way as when a baby nurses. But in this context, the oxytocin focuses the woman’s attention on her sexual partner, strengthening her desire to bond with this person.
In other words, men can and do make themselves more desirable by correctly stimulating a woman’s breasts during foreplay and sex. Evolution has, in a sense, made men want to do this.
Attraction to breasts is a brain organisation effect that occurs in straight males when they go through puberty, Evolution has selected for this brain organization in men that makes them attracted to the breasts in a sexual context, because the outcome is that it activates the female bonding circuit, making women feel more bonded with him. It’s a behaviour that males have evolved in order to stimulate the female’s maternal bonding circuitry.
So, why did this evolutionary change happen in humans, and not in other breast-feeding mammals? Young suggests that it is because we form monogamous relationships, whereas 97% of mammals do not. “Secondly, it might have to do with the fact that we are upright and have face-to-face sex, which provides more opportunity for nipple stimulation during sex. In monogamous voles, for example, the nipples are hanging toward the ground and the voles mate from behind, so this didn’t evolve, maybe the nature of our sexuality has allowed greater access to the breasts.”
Prof. Young says competing theories of men’s breast fixation don’t stand up to scrutiny. For example, the argument that men tend to select full-breasted women because they think these women’s breast fat will make them better at nourishing babies falls short when one considers that “sperm is cheap” compared with eggs, and men don’t need to be choosy.
But Young’s new theory will face scrutiny of its own. Commenting on the theory, Rutgers University anthropologist Fran Mascia-Lees, who has written extensively about the evolutionary role of breasts, said one concern is that not all men are attracted to them. “Always important whenever evolutionary biologists suggest a universal reason for a behavior and emotion: how about the cultural differences?” Mascia-Lees wrote. Also, in some African cultures, for example, women don’t cover their breasts, and men don’t seem to find them so, shall we say, titillating. I guess you could liken this to a 16 year old on a holiday on the Costa del Sol, topless women abound but after two weeks they are no longer as appealing.
Young states however, that just because breasts aren’t covered in these cultures “doesn’t mean that massaging them and stimulating them is not part of the foreplay in these cultures. As of yet, there are not very many studies that look at [breast stimulation during foreplay] in an anthropological context.”
Personally, I am very interested in furthering the research and will be looking for ‘test subjects’ in this and other areas shortly 😉