‘Disgusted’ Rats Teaching Scientists About Nausea, Work May Lead to New Cancer Treatments
Nausea is a common and distressing side effect of many drugs and treatments. Unlike vomiting, nausea is not well understood, but new research by University of Guelph scientists may soon change that.
Guelph PhD student Katharine Tuerke, neuroscience researcher Cheryl Limebeer and Prof. Linda Parker in the Department of Psychology believe they’ve found the mechanism in the brain that is responsible for the sensation of nausea – with the help of some “disgusted” rats.
Their study was published this week in Journal of Neuroscience.
“Although everyone has experienced nausea at some point, its neurobiology is poorly understood due to a lack of animal models,” said Parker, who holds the Canada Research Chair in Behavioural Neuroscience.
“We know about vomiting. The vomiting reflex is very well characterized, but the experience of nausea is something that little is known about. How is it generated? Where is it generated?”
Although rats can’t vomit, they do display a disgust reaction called gaping when re-exposed to a taste that made them feel nauseous in the past. Therefore, these gaping reactions in rats provide a model to understand brain mechanisms that produce nausea in humans.
Filed under nausea side effect emetic drugs animal model neuroscience psychology insular cortex science
The Date of Interbreeding between Neandertals and Modern Humans
Comparisons of DNA sequences between Neandertals and present-day humans have shown that Neandertals share more genetic variants with non-Africans than with Africans. This could be due to interbreeding between Neandertals and modern humans when the two groups met subsequent to the emergence of modern humans outside Africa. However, it could also be due to population structure that antedates the origin of Neandertal ancestors in Africa. We measure the extent of linkage disequilibrium (LD) in the genomes of present-day Europeans and find that the last gene flow from Neandertals (or their relatives) into Europeans likely occurred 37,000–86,000 years before the present (BP), and most likely 47,000–65,000 years ago. This supports the recent interbreeding hypothesis and suggests that interbreeding may have occurred when modern humans carrying Upper Paleolithic technologies encountered Neandertals as they expanded out of Africa.
Filed under Neandertals Modern humans DNA genomics genetics evolution interbreeding neuroscience psychology science
Morphine and cocaine affect reward sensation differently
A new study by scientists in the US has found that the opiate morphine and the stimulant cocaine act on the reward centers in the brain in different ways, contradicting previous theories that these types of drugs acted in the same way.
Morphine and cocaine both affect the flow of the neurotransmitter dopamine, which has been shown to be important in the feeling of reward. When a dopamine neuron is stimulated it releases dopamine, which is then taken up by neighboring cells. Any excess is reabsorbed into the original dopamine neuron by a process known as “reuptake.”
Cocaine is known to block reuptake, and the excess dopamine leads to an enhanced reward effect. Cocaine is also known to make the cells in the nucleus accumbens, which receives signals from the VTA, more sensitive to cocaine. It was already known a protein called brain-derived neurotrophic factor (BDNF) in the VTA region of the brain enhances the reward response to cocaine.
The new study shows that BDNF has the opposite effect when morphine is present, decreasing the reward response and the development of addiction rather than enhancing it. The researchers identified numerous genes regulated by BDNF and associated with its effects. They used genetic techniques to suppress BDNF, and then directly excited the neurons in the nucleus accumbens that normally receives transmitted impulses from the VTA.
They found that suppressing BDNF in the VTA allowed morphine to increase the excitability of dopamine neurons and hence enhance the reward. When they optically excited the dopamine terminals in the nucleus accumbens that normally receive the transmissions from the VTA, they also found a reversal in the normal effect of BDNF.
Filed under BDNF brain cocaine dopamine morphine neuron neuroscience psychology reward addiction science
Research identifies the mechanism that protects our brains from turning stress and trauma into post-traumatic stress disorder
Researchers from the University of Exeter Medical School have for the first time identified the mechanism that protects us from developing uncontrollable fear.
Our brains have the extraordinary capacity to adapt to changing environments – experts call this ‘plasticity’. Plasticity protects us from developing mental disorders as the result of stress and trauma.
Researchers found that stressful events re-programme certain receptors in the emotional centre of the brain (the amygdala), which the receptors then determine how the brain reacts to the next traumatic event.
These receptors (called protease-activated receptor 1 or PAR1) act in the same way as a command centre, telling neurons whether they should stop or accelerate their activity.
Before a traumatic event, PAR1s usually tell amygdala neurons to remain active and produce vivid emotions. However, after trauma they command these neurons to stop activating and stop producing emotions – so protecting us from developing uncontrollable fear.
This helps us to keep our fear under control, and not to develop exaggerated responses to mild or irrelevant fear triggers – for example, someone who may have witnessed a road traffic accident who develops a fear of cars or someone who may have had a dog jump up on them as a child and who now panics when they see another dog.
The research team used mice in which the PAR1 receptors were genetically de-activated and found that the animals developed a pathological fear in response to even mild, aversive stimuli.
The study was led by Professor Robert Pawlak of University of Exeter Medical School. He said: “The discovery that the same receptor can either awaken neurons or ‘switch them off’ depending on previous trauma and stress experience, adds an entirely new dimension to our knowledge of how the brain operates and emotions are formed.”
Professor Pawlak added: “We are now planning to extend our study to investigate if the above mechanisms, or genetic defects of the PAR1 receptor, are responsible for the development of anxiety disorders and depression in human patients. There is more work to be done, but the potential for the development of future therapies based on our findings is both exciting and intriguing.”
The article describing the above findings has recently been published in one of the most prestigious psychiatry journals, Molecular Psychiatry.
(Source: eurekalert.org)
Filed under brain PTSD plasticity stress PAR1s neuron neuroscience psychology science
Training computers to understand the human brain
Understanding how the human brain categorizes information through signs and language is a key part of developing computers that can ‘think’ and ‘see’ in the same way as humans. Hiroyuki Akama at the Graduate School of Decision Science and Technology, Tokyo Institute of Technology, together with co-workers in Yokohama, the USA, Italy and the UK, have completed a study using fMRI datasets to train a computer to predict the semantic category of an image originally viewed by five different people.
The participants were asked to look at pictures of animals and hand tools together with an auditory or written (orthographic) description. They were asked to silently ‘label’ each pictured object with certain properties, whilst undergoing an fMRI brain scan. The resulting scans were analysed using algorithms that identified patterns relating to the two separate semantic groups (animal or tool).
After ‘training’ the algorithms in this way using some of the auditory session data, the computer correctly identified the remaining scans 80-90% of the time. Similar results were obtained with the orthographic session data. A cross-modal approach, namely training the computer using auditory data but testing it using orthographic, reduced performance to 65-75%. Continued research in this area could lead to systems that allow people to speak through a computer simply by thinking about what they want to say.
Filed under brain fMRI semantics technology multi-voxel pattern analysis neuroscience psychology science
Dementia: The Self-Portraits of William Utermohlen
About the art work: When he learned in 1995 that he had Alzheimer’s disease, William Utermohlen, an American artist living in London, immediately began work on an ambitious series of self-portraits. The artist pursued this project over an eight-year period, adapting his style to the growing limitations of his perception and motor skills and creating images that powerfully documented his experience of his illness. The resulting body of work serves as a unique artistic, medical, and personal record of one man’s struggle with dementia.
Full Article: The Dementia Plague
Filed under brain dementia alzheimer alzheimer's disease art William Utermohlen neuroscience psychology science
What number is halfway between 1 and 9? Is it 5 — or 3?
Ask adults from the industrialized world what number is halfway between 1 and 9, and most will say 5. But pose the same question to small children, or people living in some traditional societies, and they’re likely to answer 3.
Cognitive scientists theorize that that’s because it’s actually more natural for humans to think logarithmically than linearly: 30 is 1, and 32 is 9, so logarithmically, the number halfway between them is 31, or 3. Neural circuits seem to bear out that theory. For instance, psychological experiments suggest that multiplying the intensity of some sensory stimuli causes a linear increase in perceived intensity.
In a paper that appeared online last week in the Journal of Mathematical Psychology, researchers from MIT’s Research Laboratory of Electronics (RLE) use the techniques of information theory to demonstrate that, given certain assumptions about the natural environment and the way neural systems work, representing information logarithmically rather than linearly reduces the risk of error.
Filed under brain sensory perception information theory Weber–Fechner law neuroscience psychology science
Caffeinated Coffee Linked to Loss of Vision
Consumption of caffeinated coffee is associated with an increased risk of developing exfoliation glaucoma, the leading cause of secondary glaucoma worldwide, according to a new study led by Dr Louis Pasquale of Brigham and Women’s Hospital in Boston.
Filed under brain caffeine vision glaucoma coffee consumption neuroscience psychology science
