26 August 2016
Eight people who have spent years paralyzed from spinal cord injuries have regained partial sensation and muscle control in their lower limbs after training with brain-controlled robotics. The patients used brain-machine interfaces, including a virtual reality system that used their own brain activity to simulate full control of their legs. The research led by Duke University academics offers promise for people with spinal cord injury, stroke and other conditions to regain strength, mobility and independence. Several patients saw changes after seven months of training. After a year, four patients' sensation and muscle control changed significantly enough that doctors upgraded their diagnoses from complete to partial paralysis.
Most patients saw improvements in their bladder control and bowel function, reducing their reliance on laxatives and catheters, he said. These changes reduce patients' risk of infections, which are common in patients with chronic paralysis and are a leading cause of death. Brain-machine systems establish direct communication between the brain and computers or often prosthetics, such as robotic limbs. Researchers believe with weekly training, the rehab patients re-engaged spinal cord nerves that survived the impact of the car crashes, falls and other trauma that paralyzed their lower limbs. At the beginning of rehabilitation, five participants had been paralyzed at least five years; two had been paralyzed for more than a decade.
24 August 2016
Déjà vu was thought to be caused by the brain making false memories, but researcher at the University of St Andrews, UK, now suggests this is wrong. Exactly how déjà vu works has long been a mystery, partly because it’s fleeting and unpredictable nature makes it difficult to study. Researchers developed a way to trigger the sensation of déjà vu in the lab. The technique uses a standard method to trigger false memories. It involves telling a person a list of related words – such as bed, pillow, night, dream – but not the key word linking them together (i.e. sleep). When the person is later quizzed on the words they’ve heard, they tend to believe they have also heard ‘sleep’ – a false memory. To create the feeling of déjà vu, they asked people if they had heard any words beginning with the letter ‘s’.
The volunteers replied that they hadn’t. This meant that when they were later asked if they had heard the word sleep, they were able to remember that they couldn’t have, but at the same time, the word felt familiar. They report having this strange experience of déjà vu. The team used fMRI to scan the brains of 21 volunteers while they experienced this triggered déjà vu. We might expect that areas of the brain involved in memories, such as the hippocampus, would be active during this phenomenon, but this wasn’t the case. The team found that the frontal areas of the brain that are involved in decision making were active instead. If these findings are confirmed, they suggest that déjà vu is a sign that your brain’s memory checking system is working well, and that you’re less likely to misremember events.
13 August 2016
After reflexively reaching out to grab a hot pan falling from the stove, you may be able to withdraw your hand at the very last moment to avoid getting burned. That is because the brain's executive control can step in to break a chain of automatic commands. Several new lines of evidence suggest that the same may be true when it comes to the reflex of recollection—and that the brain can halt the spontaneous retrieval of potentially painful memories. Within the brain, memories sit in a web of interconnected information. As a result, one memory can trigger another, making it bubble up to the surface without any conscious effort. When you get a reminder, the mind's automatic response is to do you a favor by trying to deliver the thing that's associated with it, neuroscientists say at the University of Cambridge. But sometimes we are reminded of things we would rather not think about. Humans are not helpless against this process, however. Previous imaging studies suggest that the brain's frontal areas can dampen the activity of the hippocampus, a crucial structure for memory, and therefore suppress retrieval.
In an effort to learn more, researchers recently investigated what happens after the hippocampus is suppressed. They asked 381 college students to learn pairs of loosely related words. Later, the students were shown one word and asked to recall the other—or to do the opposite and to actively not think about the other word. Sometimes between these tasks they were shown unusual images, such as a peacock standing in a parking lot. They found that the participants' ability to subsequently recall the peacocks and other strange pictures was about 40 percent lower if they had been instructed to suppress memories of words before or after seeing the images, compared with trials in which they had been asked to recall the words. This provides further evidence that a memory-control mechanism exists and suggests that trying to actively forget a particular memory can negatively affect general memory. They call the phenomenon an “amnesic shadow” because it apparently blocks recollection of unrelated events happening around the time of decreased hippocampal activity. The results may explain why some people who have experienced trauma have poor memory of everyday events.
12 August 2016
Many criminal offenders display psychopathic traits, such as antisocial and impulsive behaviour. And yet some individuals with psychopathic traits do not commit offences for which they are convicted. As with any other form of behaviour, psychopathic behaviour has a neurobiological basis. Researchers from the Donders Institute and the Department of Psychiatry at Radboudumc wanted to find out whether the way a psychopath’s brain works is visibly different from that of a non-psychopath. And whether there are differences between the brains of criminal and non-criminal psychopaths. Researchers in the Department of Psychiatry at Radboudumc carried out tests on 14 convicted psychopathic individuals, and 20 non-criminal individuals, half of whom had a high score on the psychopathy scale. The participants performed tests while their brain activity was measured in an MRI scanner.
They saw that the reward centre in the brains of people with many psychopathic traits (both criminal and non-criminal) were more strongly activated than those in people without psychopathic traits. It has already been proved that the brains of non-criminal individuals with psychopathic traits are triggered by the expectation of reward. This research shows that this is also the case for criminal individuals with psychopathic traits. Another interesting difference was discovered between non-criminal people with multiple psychopathic traits and criminal people with psychopathic traits. There is a difference in the communication between the reward centre and an area in the middle of the forebrain. Good communication between these areas would appear to be a condition for self-control. Results seem to indicate that the tendency to commit an offence arises from a combination of a strong focus on reward and a lack of self-control. This is the first project in which convicted criminals were actually examined.
09 August 2016
Scientists in Singapore have made a big leap on research on the ‘mini-brain’. These advanced mini versions of the human midbrain will help researchers develop treatments and conduct other studies into Parkinson’s Disease (PD) and ageing-related brain diseases. These mini midbrain versions are three-dimensional miniature tissues that are grown in the laboratory and they have certain properties of specific parts of the human brains. This is the first time that the black pigment neuromelanin has been detected in an organoid model. The study also revealed functionally active dopaminergic neurons. The human midbrain, which is the information superhighway, controls auditory, eye movements, vision and body movements. It contains special dopaminergic neurons that produce dopamine – which carries out significant roles in executive functions, motor control, motivation, reinforcement, and reward.
Also causing PD is the dramatic reduction in neuromelanin production, leading to the degenerative condition of patients, which includes tremors and impaired motor skills. This creation is a key breakthrough for studies in PD, which affects an estimated seven to 10 million people worldwide. Furthermore, there are people who are affected by other causes of parkinsonism. Researchers now have access to the material that is affected in the disease itself, and different types of studies can be conducted in the laboratory instead of through simulations or on animals. Using stem cells, scientists have grown pieces of tissue, known as brain organoids, measuring about 2 to 3 mm long. These organoids contain the necessary hallmarks of the human midbrain, which are dopaminergic neurons and neuromelanin.