Posts tagged temporal lobe
Articles and news from the latest research reports.
What happens in our brain when we unlock a door?
People who are unable to button up their jacket or who find it difficult to insert a key in lock suffer from a condition known as apraxia. This means that their motor skills have been impaired – as a result of a stroke, for instance. Scientists in Munich have now examined the parts of the brain that are responsible for planning and executing complex actions. They discovered that there is a specific network in the brain for using tools. Their findings have been published in the Journal of Neuroscience.
Researchers from Technische Universität München (TUM) and the Klinikum rechts der Isar hospital have analyzed the brain networks that control the use of tools or other utensils. Their chosen method of functional magnetic resonance imaging (fMRI) shows the areas of the brain that are activated when a person thinks, moves and performs actions.
The use of tools is an essential human skill. “Numerous studies are investigating the neural processes at play when we pick up a tool,” says Prof. Joachim Hermsdörfer from TUM’s Chair of Human Movement Science. “But many of these studies are restricted to test subjects observing an action, miming it, or simply visualizing it.” The aim of this latest study was to analyze the basic neural principles of tool use under the most realistic conditions possible.
In the MRI study, the subjects received ten everyday objects, including a hammer, a bottle-opener, a key, a lighter and a scissors as well as some unfamiliar objects. Their task was to either use the objects or simply lift them up and place them down again, first with the left and then with the right hand. When they analyzed the data, the scientists looked at the planning phase and the actual execution phase separately. In this way, they were able to identify the brain networks that were activated while the subjects planned and used a tool and those that controlled execution.
Tool-specific network in the brain
One important finding was that the left hemisphere was activated when the subjects planned to use a tool – regardless of the hand they held it in. In addition, the researchers recognized a distributed network responsible for both planning and execution. When working with unfamiliar objects, these regions of the brain were less activated.
The “tool network” consists of brain regions of the parietal and frontal lobes as well as regions in the posterior temporal lobe and another area in the lateral occipital lobe. What the researchers found, therefore, was a neural activation pattern that covered all elements of a complex action. This includes recognizing the objects as tools, understanding how they are used, and the motor action to actually use the tool.
“The study also allowed us to confirm that there are different streams of perception in the brain for different tasks,” explains Hermsdörfer. The dorsal stream of perception conducts signals to the posterior parietal lobe and is generally responsible for controlling actions. “It can be divided into two function-specific processing pathways. The dorso-dorsal stream controls basic gripping and movement processes, regardless of whether the person is familiar with the object or not. A second ventro-dorsal stream becomes active when we use tools that are familiar to us.
Armed with knowledge about the localization of these “action modules”, doctors could in future provide a more differentiated diagnosis of apraxia and develop improved therapeutic approaches.
Newly-Approved Brain Stimulator Offers Hope for Individuals With Uncontrolled Epilepsy
A recently FDA-approved device has been shown to reduce seizures in patients with medication-resistant epilepsy by as much as 50 percent. When coupled with an innovative electrode placement planning system developed by physicians at Rush, the device facilitated the complete elimination of seizures in nearly half of the implanted Rush patients enrolled in the decade-long clinical trials.
That’s good news for a large portion of the nearly 400,000 people in the U.S. living with epilepsy whose seizures can’t be controlled with medications and who are not candidates for brain surgery.
Epilepsy is a chronic neurological condition characterized by recurrent seizures that disrupt the senses, or can involve short periods of unconsciousness or convulsions. “Many people with epilepsy have scores of unpredictable seizures every day that make it impossible for them to drive, work or even get a good night’s sleep,” said Dr. Marvin Rossi, co-principal investigator of the NeuroPace Pivotal Clinical Trial and assistant professor of neurology at the Rush Epilepsy Center.
The NeuroPace RNS System uses responsive, or ‘on-demand’ direct stimulation to detect abnormal electrical activity in the brain and deliver small amounts of electrical stimulation to suppress seizures before they begin.
The device is surgically placed underneath the scalp within the skull and connected to electrodes that are strategically placed within the brain where the seizures originate (called the seizure focus). A programmed computer chip in the skull communicates with the system to record data and to help regulate responsive stimulation.
The unique electrode placement planning modeling system developed at Rush uses a computer-intensive mapping system that facilitates surgical placement of electrodes at the precise location in the brain’s temporal lobe circuitry. When stimulated, these extensive epileptic circuits are calmed. The modeling system predicts where in the brain the activity begins and spreads, so that the device can better influence the maximal extent of the epileptic pathway.
The device also acts as an implanted EEG for recording brain activity. This function was first shown at Rush to help determine whether the patient will further benefit from a surgical resection, in which surgeons remove a portion of the temporal lobe network. Dr. Richard Byrne, chairman of Neurosurgery at Rush, implants the electrodes in the temporal lobes.
As a result, physicians at Rush can offer patients the new implantable neurostimulator device, a surgical resection or both with the possibility of completely eliminating seizures. “This device is also being used at Rush as a foundation and inspiration for building cutting-edge hybrid stimulation therapy-drug molecule delivery systems,” said Rossi.
“Devices that treat epilepsy may offer new hope to patients when medication is ineffective and resection is not an option,” said Rossi. “Not long ago, it was highly unlikely that these patients would ever be free of their seizures. Now, several of our Rush patients with this device are actually able to drive, lower or even eliminate their medications and aren’t as limited as they once were. There is no doubt that quality of life of the majority of our implanted patients is significantly improved.”
According to the Centers for Disease Control and Prevention, in 2010, epilepsy affected approximately 2.3 million adults in the U.S. and 467,711 children under the age of 17.
(Source: rush.edu)
Study reveals how ecstasy acts on the brain and hints at therapeutic uses
Brain imaging experiments have revealed for the first time how ecstasy produces feelings of euphoria in users.
Results of the study at Imperial College London, parts of which were televised in Drugs Live on Channel 4 in 2012, have now been published in the journal Biological Psychiatry.
The findings hint at ways that ecstasy, or MDMA, might be useful in the treatment of anxiety and post-traumatic stress disorder (PTSD).
MDMA has been a popular recreational drug since the 1980s, but there has been little research on which areas of the brain it affects. The new study is the first to use functional magnetic resonance imaging (fMRI) on resting subjects under its influence.
Twenty-five volunteers underwent brain scans on two occasions, one after taking the drug and one after taking a placebo, without knowing which they had been given.
The results show that MDMA decreases activity in the limbic system – a set of structures involved in emotional responses. These effects were stronger in subjects who reported stronger subjective experiences, suggesting that they are related.
Communication between the medial temporal lobe and medial prefrontal cortex, which is involved in emotional control, was reduced. This effect, and the drop in activity in the limbic system, are opposite to patterns seen in patients who suffer from anxiety.
MDMA also increased communication between the amygdala and the hippocampus. Studies on patients with PTSD have found a reduction in communication between these areas.
The project was led by David Nutt, the Edmond J. Safra Professor of Neuropsychopharmacology at Imperial College London, and Professor Val Curran at UCL.
Dr Robin Carhart-Harris from the Department of Medicine at Imperial, who performed the research, said: “We found that MDMA caused reduced blood flow in regions of the brain linked to emotion and memory. These effects may be related to the feelings of euphoria that people experience on the drug.”
Professor Nutt added: “The findings suggest possible clinical uses of MDMA in treating anxiety and PTSD, but we need to be careful about drawing too many conclusions from a study in healthy volunteers. We would have to do studies in patients to see if we find the same effects.”
MDMA has been investigated as an adjunct to psychotherapy in the treatment of PTSD, with a recent pilot study in the US reporting positive preliminary results.
As part of the Imperial study, the volunteers were asked to recall their favourite and worst memories while inside the scanner. They rated their favourite memories as more vivid, emotionally intense and positive after MDMA than placebo, and they rated their worst memories less negatively. This was reflected in the way that parts of the brain were activated more or less strongly under MDMA. These results were published in the International Journal of Neuropsychopharmacology.
Dr Carhart-Harris said: “In healthy volunteers, MDMA seems to lessen the impact of painful memories. This fits with the idea that it could help patients with PTSD revisit their traumatic experiences in psychotherapy without being overwhelmed by negative emotions, but we need to do studies in PTSD patients to see if the drug affects them in the same way.”
Exercise May be the Best Medicine for Alzheimer’s
New research out of the University of Maryland School of Public Health shows that exercise may improve cognitive function in those at risk for Alzheimer’s by improving the efficiency of brain activity associated with memory. Memory loss leading to Alzheimer’s disease is one of the greatest fears among older Americans. While some memory loss is normal and to be expected as we age, a diagnosis of mild cognitive impairment, or MCI, signals more substantial memory loss and a greater risk for Alzheimer’s, for which there currently is no cure.
The study, led by Dr. J. Carson Smith, assistant professor in the Department of Kinesiology, provides new hope for those diagnosed with MCI. It is the first to show that an exercise intervention with older adults with mild cognitive impairment (average age 78) improved not only memory recall, but also brain function, as measured by functional neuroimaging (via fMRI). The findings are published in the Journal of Alzheimer’s Disease.
“We found that after 12 weeks of being on a moderate exercise program, study participants improved their neural efficiency – basically they were using fewer neural resources to perform the same memory task,” says Dr. Smith. “No study has shown that a drug can do what we showed is possible with exercise.”
Recommended Daily Activity: Good for the Body, Good for the Brain
Two groups of physically inactive older adults (ranging from 60-88 years old) were put on a 12-week exercise program that focused on regular treadmill walking and was guided by a personal trainer. Both groups – one which included adults with MCI and the other with healthy brain function – improved their cardiovascular fitness by about ten percent at the end of the intervention. More notably, both groups also improved their memory performance and showed enhanced neural efficiency while engaged in memory retrieval tasks.
The good news is that these results were achieved with a dose of exercise consistent with the physical activity recommendations for older adults. These guidelines urge moderate intensity exercise (activity that increases your heart rate and makes you sweat, but isn’t so strenuous that you can’t hold a conversation while doing it) on most days for a weekly total of 150 minutes.
Measuring Exercise’s Impact on Brain Health and Memory
One of the first observable symptoms of Alzheimer’s disease is the inability to remember familiar names. Smith and colleagues had study participants identify famous names and measured their brain activation while engaged in correctly recognizing a name – e.g., Frank Sinatra, or other celebrities well known to adults born in the 1930s and 40s. “The task gives us the ability to see what is going on in the brain when there is a correct memory performance,” Smith explains.
Tests and imaging were performed both before and after the 12-week exercise intervention. Brain scans taken after the exercise intervention showed a significant decrease in the intensity of brain activation in eleven brain regions while participants correctly identified famous names. The brain regions with improved efficiency corresponded to those involved in the pathology of Alzheimer’s disease, including the precuneus region, the temporal lobe, and the parahippocampal gyrus.
The exercise intervention was also effective in improving word recall via a “list learning task,” i.e., when people were read a list of 15 words and asked to remember and repeat as many words as possible on five consecutive attempts, and again after a distraction of being given another list of words.
“People with MCI are on a very sharp decline in their memory function, so being able to improve their recall is a very big step in the right direction,” Smith states.
The results of Smith’s study suggest that exercise may reduce the need for over-activation of the brain to correctly remember something. That is encouraging news for those who are looking for something they can do to help preserve brain function.
Dr. Smith has plans for a larger study that would include more participants, including those who are healthy but have a genetic risk for Alzheimer’s, and follow them for a longer time period with exercise in comparison to other types of treatments. He and his team hope to learn more about the impact of exercise on brain function and whether it could delay the onset or progression of Alzheimer’s disease.
Scientists identify key to learning new words
For the first time scientists have identified how a pathway in the brain which is unique to humans allows us to learn new words.
The average adult’s vocabulary consists of about 30,000 words. This ability seems unique to humans as even the species closest to us - chimps - manage to learn no more than 100.
It has long been believed that language learning depends on the integration of hearing and repeating words but the neural mechanisms behind learning new words remained unclear. Previous studies have shown that this may be related to a pathway in the brain only found in humans and that humans can learn only words that they can articulate.
Now researchers from King’s College London Institute of Psychiatry, in collaboration with Bellvitge Biomedical Research Institute (IDIBELL) and the University of Barcelona, have mapped the neural pathways involved in word learning among humans. They found that the arcuate fasciculus, a collection of nerve fibres connecting auditory regions at the temporal lobe with the motor area located at the frontal lobe in the left hemisphere of the brain, allows the ‘sound’ of a word to be connected to the regions responsible for its articulation. Differences in the development of these auditory-motor connections may explain differences in people’s ability to learn words.
The results of the study are published in the journal Proceedings of the National Academy of Sciences (PNAS).
Dr Marco Catani, co-author from the NatBrainLab at King’s College London Institute of Psychiatry said: “Often humans take their ability to learn words for granted. This research sheds new light on the unique ability of humans to learn a language, as this pathway is not present in other species. The implications of our findings could be wide ranging – from how language is taught in schools and rehabilitation from injury, to early detection of language disorders such as dyslexia. In addition these findings could have implications for other disorders where language is affected such as autism and schizophrenia.”
The study involved 27 healthy volunteers. Researchers used diffusion tensor imaging to image the structure of the brain before a word learning task and functional MRI, to detect the regions in the brain that were most active during the task. They found a strong relationship between the ability to remember words and the structure of arcuate fasciculus, which connects two brain areas: the territory of Wernicke, related to auditory language decoding, and Broca’s area, which coordinates the movements associated with speech and the language processing.
In participants able to learn words more successfully their arcuate fasciculus was more myelinated i.e. the nervous tissue facilitated faster conduction of the electrical signal. In addition the activity between the two regions was more co-ordinated in these participants.
Dr Catani concludes, “Now we understand that this is how we learn new words, our concern is that children will have less vocabulary as much of their interaction is via screen, text and email rather than using their external prosthetic memory. This research reinforces the need for us to maintain the oral tradition of talking to our children.”
(Source: kcl.ac.uk)
Path of Plaque Buildup in Brain Shows Promise as Early Biomarker for Alzheimer’s Disease
The trajectory of amyloid plaque buildup—clumps of abnormal proteins in the brain linked to Alzheimer’s disease—may serve as a more powerful biomarker for early detection of cognitive decline rather than using the total amount to gauge risk, researchers from Penn Medicine’s Department of Radiology suggest in a new study published online July 15 in the Journal of Neurobiology of Aging.
Amyloid plaque that starts to accumulate relatively early in the temporal lobe, compared to other areas and in particular to the frontal lobe, was associated with cognitively declining participants, the study found. “Knowing that certain brain abnormality patterns are associated with cognitive performance could have pivotal importance for the early detection and management of Alzheimer’s,” said senior author Christos Davatzikos, PhD, professor in the Department of Radiology, the Center for Biomedical Image Computing and Analytics, at the Perelman School of Medicine at the University of Pennsylvania.
Today, memory decline and Alzheimer’s—which 5.4 million Americans live with today—is often assessed with a variety of tools, including physical and bio fluid tests and neuroimaging of total amyloid plaque in the brain. Past studies have linked higher amounts of the plaque in dementia-free people with greater risk for developing the disorder. However, it’s more recently been shown that nearly a third of people with plaque on their brains never showed signs of cognitive decline, raising questions about its specific role in the disease.
Now, Dr. Davatzikos and his Penn colleagues, in collaboration with a team led by Susan M. Resnick, PhD, Chief, Laboratory of Behavioral Neuroscience at the National Institute on Aging (NIA), used Pittsburgh compound B (PiB) brain scans from the Baltimore Longitudinal Study of Aging’s Imaging Study and discovered a stronger association between memory decline and spatial patterns of amyloid plaque progression than the total amyloid burden.
“It appears to be more about the spatial pattern of this plaque progression, and not so much about the total amount found in brains. We saw a difference in the spatial distribution of plaques among cognitive declining and stable patients whose cognitive function had been measured over a 12-year period. They had similar amounts of amyloid plaque, just in different spots,” Dr. Davatzikos said. “This is important because it potentially answers questions about the variability seen in clinical research among patients presenting plaque. It accumulates in different spatial patterns for different patients, and it’s that pattern growth that may determine whether your memory declines.”
The team, including first author Rachel A. Yotter, PhD, a postdoctoral researcher in the Section for Biomedical Image Analysis, retrospectively analyzed the PET PiB scans of 64 patients from the NIA’s Baltimore Longitudinal Study of Aging whose average age was 76 years old. For the study, researchers created a unique picture of patients’ brains by combining and analyzing PET images measuring the density and volume of amyloid plaque and their spatial distribution within the brain. The radiotracer PiB allowed investigators to see amyloid temporal changes in deposition.
Those images were then compared to California Verbal Learning Test (CLVT) scores, among other tests, from the participants to determine the longitudinal cognitive decline. The group was then broken up into two subgroups: the most stable and the most declining individuals (26 participants).
Despite lack of significant difference in the total amount of amyloid in the brain, the spatial patterns between the two groups (stable and declining) were different, with the former showing relatively early accumulation in the frontal lobes and the latter in the temporal lobes.
A particular area of the brain may be affected early or later depending on the amyloid trajectory, according to the authors, which in turn would affect cognitive impairment. Areas affected early with the plaque include the lateral temporal and parietal regions, with sparing of the occipital lobe and motor cortices until later in disease progression.
“This finding has broad implications for our understanding of the relationship between cognitive decline and resistance and amyloid plaque location, as well as the use of amyloid imaging as a biomarker in research and the clinic,” said Dr Davatzikos. “The next step is to investigate more individuals with mild cognitive impairment, and to further investigate the follow-up scans of these individuals via the BLSA study, which might shed further light on its relevance for early detection of Alzheimer’s.”
(Source: uphs.upenn.edu)
How two brain areas interact to trigger divergent emotional behaviors
New research from the University of North Carolina School of Medicine for the first time explains exactly how two brain regions interact to promote emotionally motivated behaviors associated with anxiety and reward.
The findings could lead to new mental health therapies for disorders such as addiction, anxiety, and depression. A report of the research was published online by the journal, Nature, on March 20, 2013.
Located deep in the brain’s temporal lobe are tightly packed clusters of brain cells in the almond shaped amygdala that are important for processing memory and emotion. When animals or people are in stressful situations, neurons in an extended portion of the amygdala called the bed nucleus of the stria terminalis, or BNST, become hyperactive.
But, almost paradoxically, neurons in the BNST, which modulate fear and anxiety, reach into a portion of the midbrain that’s involved in behavioral responses to reward, the ventral tegmental area, or VTA.
“For many years it’s been known that dopamine neurons in the VTA are involved in reward processing and motivation. For example, they’re activated during exposure to drugs of abuse and naturally rewarding experiences,” says study senior author Garret Stuber, PhD, assistant professor in the departments of Psychiatry and Cell Biology and Physiology, and the UNC Neuroscience Center. “On the one hand, you have this area of the brain – the BNST – that’s associated with aversion and anxiety, but it’s in direct communication with a brain reward center. We wanted to figure out exactly how these two brain regions interact to promote different types of behavioral responses related to anxiety and reward.”
In the past, researchers have tried to get a glimpse into the inner workings of the brain using electrical stimulation or drugs, but those techniques couldn’t quickly and specifically change only one type of cell or one type of connection. But optogenetics, a technique that emerged about seven years ago, can.
In the technique, scientists transfer light-sensitive proteins called “opsins” – derived from algae or bacteria that need light to grow – into the mammalian brain cells they wish to study. Then they shine laser beams onto the genetically manipulated brain cells, either exciting or blocking their activity with millisecond precision.