Posts tagged brainwaves
Articles and news from the latest research reports.
Electrical stimulation of brain alters dreams
Nighttime dreams in which you show up at work naked, encounter an ax-wielding psychopath or experience other tribulations may become a thing of the past thanks to a discovery reported on Sunday.
Applying electrical current to the brain, according to a study published online in Nature Neuroscience, induces “lucid dreaming,” in which the dreamer is aware that he is dreaming and can often gain control of the ongoing plot.
The findings are the first to show that inducing brain waves of a specific frequency produces lucid dreaming.
The Ways to Control Dreaming
In 2008, Isaac Katz, a civil service officer, passed away just before reaching his 78th birthday. He had been struggling with cardiovascular problems for some time. His son, Arnon Katz, now a 47-year-old tech entrepreneur, was beside himself with grief, and frustrated by the fact that he would never speak to his father again.
At the time, the younger Katz had been training himself to lucid dream—a phenomenon in which the dreamer becomes aware they are dreaming and can potentially control their actions as well as the content and context of the dream. But despite keeping a dream journal and diligently practicing other techniques, hadn’t had any success. All that changed, though, a year after his father’s death.
Katz recalled in a recent phone interview that he was mid-dream when his mother suddenly warned him in a voiceover, “Hey, you’re dreaming right now, so don’t take what your father is saying too seriously.”
Katz told me, “Suddenly everything slowed down and became incredibly vivid and real. I knew I was dreaming, but I felt I was with my father and could choose what to say as if I was awake. When I woke up, I realized that our brains are capable of creating an entire reality apart from waking life.” Many other lucid dreamers have said something similar.
Katz said the experience allowed him to finally “close the circle.” The frustration he felt in the year following his father’s death was gone.
Researcher: More study needed on interrogation techniques that measure brain waves
When police in Spain tried to locate two murder victims last year, they sought assistance on places to search from a tool that measured the brain activity of the convicted and confessed killers.
The technology, known as Brain Fingerprinting, developed by the American-based company Government Works Inc., basically seeks to use brain wave data in response to certain stimuli or details to determine whether a person is telling the truth. U.S. courts have sparingly allowed the higher-tech version of the traditional polygraph test or lie detector, and it has aided in both exoneration and conviction in American cases.
As the use of Brain Fingerprinting has expanded beyond the United States, a University of Kansas researcher argues the technology is based on an incorrect assumption about how human memory works.
"At the very least, we need to ask them to do several more methodological checks and make sure that whenever these technologies are used in legal contexts, we make clear the limitations of that technology," said Sarah Robins, an assistant professor of philosophy who studies the philosophy of neuroscience and related issues in neuroethics. “Maybe there’s a stronger claim here that this should never make it into court, but my stance is to say: ‘Let’s think about the technology and the assumptions behind it.’”
Robins details the theoretical issues surrounding Brain Fingerprinting in her essay “Memory Traces, Memory Errors, and the Possibility of Neural Lie Detection,” which will appear in “Brain Theory,” edited by Charles Wolfe. Also in Wolfe’s book, John Symons, a KU professor of philosophy, has co-authored the chapter “Computing with Bodies: Morphology, Function, and Computational Theory.”
Wolfe, a research fellow of the Department of Philosophy and Moral Sciences at the University of Ghent in Belgium, is scheduled to speak at 7 p.m. Friday, May 2, at the Kansas Room of the Kansas Union.
(Source: news.ku.edu)
Laughter May Work Like Meditation in the Brain
Laughter triggers brain waves similar to those associated with meditation, according to a small new study.
It also found that other forms of stimulation produce different types of brain waves.
The study included 31 people whose brain waves were monitored while they watched humorous, spiritual or distressing video clips. While watching the humorous videos, the volunteers’ brains had high levels of gamma waves, which are the same ones produced during meditation, researchers found.
During the spiritual videos, the participants’ brains showed higher levels of alpha brain waves, similar to when a person is at rest. The distressing videos caused flat brain wave bands, similar to when a person feels detached, nonresponsive or doesn’t want to be in a certain situation.
Researchers were led by Lee Berk, an associate professor in the School of Allied Health Professions, and an associate research professor of pathology and human anatomy in the School of Medicine, at Loma Linda University, in California.
The study was scheduled to be presented Sunday at the Experimental Biology meeting held in San Diego. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
“What we have found in our study is that humor associated with mirthful laughter sustains high-amplitude gamma-band oscillations. Gamma is the only frequency found in every part of the brain,” Berk said in a university news release.
“What this means is that humor actually engages the entire brain — it is a whole brain experience with the gamma wave band frequency and humor, similar to meditation, holds it there; we call this being ‘in the zone,’” Berk explained.
He said that with laughter, “it’s as if the brain gets a workout.” This effect is important because it “allows for the subjective feeling states of being able to think more clearly and have more integrative thoughts,” Berk said. “This is of great value to individuals who need or want to revisit, reorganize or rearrange various aspects of their lives or experiences, to make them feel whole or more focused.”
Controlling Brain Waves to Improve Vision
Have you ever accidently missed a red light or a stop sign? Or have you heard someone mention a visible event that you passed by but totally missed seeing?
“When we have different things competing for our attention, we can only be aware of so much of what we see,” said Kyle Mathewson, Beckman Institute Postdoctoral Fellow. “For example, when you’re driving, you might really be concentrating on obeying traffic signals.”
But say there’s an unexpected event: an emergency vehicle, a pedestrian, or an animal running into the road—will you actually see the unexpected, or will you be so focused on your initial task that you don’t notice?
“In the car, we may see something so brief or so faint, while we’re paying attention to something else, that the event won’t come into our awareness,” says Mathewson. “If you present this scenario hundreds of times to someone, sometimes they will see the unexpected event, and sometimes they won’t because their brain is in a different preparation state.”
By using a novel technique to test brain waves, Mathewson and colleagues are discovering how the brain processes external stimuli that do and don’t reach our awareness. A paper about their results, “Dynamics of Alpha Control: Preparatory Suppression of Posterior Alpha Oscillations by Frontal Modulators Revealed with Combined EEG and Event-related Optical Signal,” published this month in the Journal of Cognitive Neuroscience, reveals how alpha waves, typically thought of as your brain’s electrical activity while it’s at rest, can actually influence what we see or don’t see.
The researchers used both electroencephalography (EEG) and the event-related optical signal (EROS), developed in the Cognitive Neuroimaging Laboratory of Gabriele Gratton and Monica Fabiani, professors of psychology and members of the Beckman Institute’s Cognitive Neuroscience Group, and authors of the study.
While EEG records the electrical activity along the scalp, EROS uses infrared light passed through optical fibers to measure changes in optical properties in the active areas of the cerebral cortex. Because of the hard skull between the EEG sensors and the brain, it can be difficult to find exactly WHERE signals are produced. EROS, which examines how light is scattered, can noninvasively pinpoint activity within the brain.
“EROS is based on near-infrared light,” explained Fabiani and Gratton via email. “It exploits the fact that when neurons are active, they swell a little, becoming slightly more transparent to light: this allows us to determine when a particular part of the cortex is processing information, as well as where the activity occurs.”
This allowed the researchers to not only measure activity in the brain, but also allowed them to map where the alpha oscillations were originating. Their discovery: the alpha waves are produced in the cuneus, located in the part of the brain that processes visual information.
The alpha can inhibit what is processed visually, making it hard for you to see something unexpected.
By focusing your attention and concentrating more fully on what you are experiencing, however, the executive function of the brain can come into play and provide “top-down” control—putting a brake on the alpha waves, thus allowing you to see things that you might have missed in a more relaxed state.
“We found that the same brain regions known to control our attention are involved in suppressing the alpha waves and improving our ability to detect hard-to-see targets,” said Diane Beck, a member of the Beckman’s Cognitive Neuroscience Group, and one of the study’s authors.
“Knowing where the waves originate means we can target that area specifically with electrical stimulation” said Mathewson. “Or we can also give people moment-to-moment feedback, which could be used to alert drivers that they are not paying attention and should increase their focus on the road ahead, or in other situations alert students in a classroom that they need to focus more, or athletes, or pilots and equipment operators.”
The study examined 16 subjects and mapped the electrical and optical data onto individual MRI brain images.
Why your nose can be a pathfinder
When I was a child I used to sit in my grandfather’s workshop, playing with wood shavings. Freshly shaven wood has a distinct smell of childhood happiness, and whenever I get a whiff of that scent my brain immediately conjures up images of my grandfather at his working bench, the heat from the fireplace and the dog next to it.
Researchers at the Kavli Institute for Systems Neuroscience have recently discovered the process behind this phenomenon. The brain, it turns out, connects smells to memories through an associative process where neural networks are linked through synchronised brain waves of 20-40 Hz.
– We all know that smell is connected to memories, Kei Igarashi, lead author, explains.– We know that neurons in different brain regions need to oscillate in synchrony for these regions to speak effectively to each other. Still, the relationship between interregional coupling and formation of memory traces has remained poorly understood. So we designed a task to investigate how odour-place representation evolved in the entorhinal and hippocampal region, to figure out whether learning depends on coupling of oscillatory networks.
Smell guides the way in maze
The researchers designed a maze for rats, where a rat would see a hole to poke its nose into. When poking into the hole, the rat was presented with one of two alternative smells. One smell told the rat that food would be found in the left food cup behind the rat. The other smell told it that there was food in the right cup. The rat would soon learn which smell would lead to a reward where. After three weeks of training, the rats chose correctly on more than 85% of the trials. In order to see what happened inside the brain during acquisition, 16–20 electrode pairs were inserted in the hippocampus and in different areas of the entorhinal cortex.
After the associations between smell and place were well established, the researchers could see a pattern of brain wave activity (the electrical signal from a large number of neurons) during retrieval.
Coherent brain activity evolves with learning
– Immediately after the rat is exposed to the smell there is a burst in activity of 20–40 Hz waves in a specific connection between an area in the entorhinal cortex, lateral entorhinal cortex (LEC), and an area in the hippocampus, distal CA1 (dCA1), while a similar strong response was not observed in other connections, Igarashi explains.
This coherence of 20–40 Hz activity in the LEC and dCA1 evolved in parallel with learning, with little coherence between these areas before training started. By the time the learning period was over, cells were phase locked to the oscillation and a large portion of the cells responded specifically to one or the other of the smell-odour pairs.
Long distance communication in brain mediated by waves
– This is not the first time we observe that the brain uses synchronised wave activity to establish network connections, Edvard Moser, director of the Kavli Institute for Systems Neuroscience says. – Both during encoding and retrieval of declarative memories there is an interaction between these areas mediated through gamma and theta oscillations. However, this is the first study to relate the development of a specific band of oscillations to memory performance in the hippocampus. Together, the evidence is now piling up and pointing in the direction of cortical oscillations as a general mechanism for mediating interactions among functionally specialised neurons in distributed brain circuits.
So, there you have it – the signals from your nose translate and connect to memories in an orchestrated symphony of signals in your head. Each of these memories connects to a location, pinpointed on your inner map. So when you feel a wave of reminiscence triggered by a fragrance, think about how waves created this connection in the first place.
How the brain recognizes familiar music
Research from McGill University reveals that the brain’s motor network helps people remember and recognize music that they have performed in the past better than music they have only heard. A recent study by Prof. Caroline Palmer of the Department of Psychology sheds new light on how humans perceive and produce sounds, and may pave the way for investigations into whether motor learning could improve or protect memory or cognitive impairment in aging populations. The research is published in the journal Cerebral Cortex.
“The memory benefit that comes from performing a melody rather than just listening to it, or saying a word out loud rather than just hearing or reading it, is known as the ’production effect’ on memory”, says Prof. Palmer, a Canada Research Chair in Cognitive Neuroscience of Performance. “Scientists have debated whether the production effect is due to motor memories, such as knowing the feel of a particular sequence of finger movements on piano keys, or simply due to strengthened auditory memories, such as knowing how the melody tones should sound. Our paper provides new evidence that motor memories play a role in improving listeners’ recognition of tones they have previously performed.”
For the study, researchers recruited twenty skilled pianists from Lyon, France. The group was asked to learn simple melodies by either hearing them several times or performing them several times on a piano. Pianists then heard all of the melodies they had learned, some of which contained wrong notes, while their brain electric signals were measured using electroencephalography (EEG).
“We found that pianists were better at recognizing pitch changes in melodies they had performed earlier,” said the study’s first author, Brian Mathias, a McGill PhD student who conducted the work at the Lyon Neuroscience Research Centre in France with additional collaborators Drs. Barbara Tillmann and Fabien Perrin.
The team found that EEG measurements revealed larger changes in brain waves and increased motor activity for previously performed melodies than for heard melodies about 200 milliseconds after the wrong notes. This reveals that the brain quickly compares incoming auditory information with motor information stored in memory, allowing us to recognize whether a sound is familiar.
“This paper helps us understand ‘experiential learning’, or ‘learning by doing’, and offers pedagogical and clinical implications,” said Mathias, “The role of the motor system in recognizing music, and perhaps also speech, could inform education theory by providing strategies for memory enhancement for students and teachers.”
(Source: mcgill.ca)
Figure 1: Typical slow gamma (left), fast gamma (center) and theta (right) brain-wave patterns measured during voluntary actions in rats.
Banding together to control movement
Synchrony is critical for the proper functioning of the brain. Synchronous firing of neurons within regions of the brain and synchrony between brain waves in different regions facilitate information processing, yet researchers know very little about these neural codes. Now, new research led by Tomoki Fukai of the RIKEN Brain Science Institute reveals how one region of the brain uses multiple brain-wave frequency bands to control movement.
Control of movement requires activation of numerous muscle groups in correct sequence, a function achieved by the motor cortex. To investigate the contribution of brain waves to this process, Fukai and his colleagues inserted multi-channel electrodes into the motor cortex of rats to record brain-wave patterns as the animals learned to push, hold and then pull a lever to obtain a food reward. They also developed a machine-learning technique to extract spike sequences of individual neurons from the recorded waves.
Fukai and his colleagues found that brain waves of different frequencies appeared during distinct stages of the movements. Fast gamma waves, with frequencies of around 100 hertz, were most prominent when the rats pushed or pulled the lever, whereas slow gamma waves, with frequencies of 25–40 hertz, peaked when the rats held the lever to prepare for the next pull. Theta waves (4–10 hertz) peaked while the rats held the lever, and the initiation of the pulling movement coincided with a specific phase of these oscillations (Fig. 1).
Both frequencies of gamma waves were coupled to the theta waves such that the peaks of all three brain-wave frequencies occurred at the same time. The activity of different types of nerve cells in different layers of the motor cortex was also synchronized with specific brain-wave frequencies. Importantly, cells encoding different stages of the sequential movements fired in distinct phases of the theta waves.
The results suggest that theta waves play an important role in coordinating the neuronal activity underlying the planning and execution of voluntary movement. Theta waves are known to be important for the processing of spatial information in the hippocampus, but this is the first time that a similar code has been observed in the motor cortex.
“We are currently using machine-learning techniques to study how phase-locked spikes in different layers of the motor cortex encode motor information,” says Fukai. “We are also studying whether a similar oscillatory coordination takes place in the prefrontal cortex during decision-making.”
Disease and sleep: Recent studies find new links
One in five U.S. adults shows signs of chronic sleep deprivation, and a shortage of sleep has been linked to health problems as different as diabetes and Alzheimer’s disease. Recent studies have found some interesting connections between illness and what is happening in our brains as we snooze.
Synaptic mechanisms of brain waves
Team at IST Austria examines synaptic mechanisms of rhythmic brain waves • Achievement possible through custom-design tools developed in collaboration with the institute’s Miba machine shop
How information is processed and encoded in the brain is a central question in neuroscience, as it is essential for high cognitive function such as learning and memory. Theta-gamma oscillations are “brain waves” observed in the hippocampus of behaving rats, a brain region involved in learning and memory. In rodents, theta-gamma oscillations are associated with information processing during exploration and spatial navigation. However, the underlying synaptic mechanisms have so far remained unclear. In research published this week in the journal Neuron, postdoc Alejandro Pernía-Andrade and Professor Peter Jonas, both at the Institute of Science and Technology Austria (IST Austria), discovered the synaptic mechanisms underlying oscillations at the dentate gyrus (main entrance of the hippocampus). Furthermore, the researchers suggest a role for these oscillations in the coding of information by the dentate gyrus principal neurons. Thus, these findings contribute to a better understanding of how information is processed in the brain.
Brain oscillations are, in fact, rhythmic changes in voltage in the extracellular space, referred to as electrical brain signals associated with the processing of information. These electrical signals are similar to those seen in electro-encephalographic recordings (EEG) in humans. Pernía-Andrade and Jonas observed these oscillations in a brain region called the hippocampus in behaving rats, and recorded oscillations occurring in this area using extracellular probes. To understand how oscillations are generated and which synaptic events trigger these oscillations, the researchers looked at synaptic transmission in granule cells (principal cells at the main entrance of the hippocampus) from both the extracellular (oscillations) and the intracellular perspectives (synaptic currents and neuronal firing), and then correlated the two. They discovered that excitatory and inhibitory synaptic signals contributed to different frequencies of oscillations, with excitation from the entorhinal cortex generating theta oscillations and inhibition by local dentate gyrus interneurons generating gamma oscillations. Together, excitation and inhibition provide the rhythmic signals of oscillations. It has been speculated that oscillations may help the dentate gyrus to encode information by acting as reference signals in temporal coding. Pernía-Andrade and Jonas now show that granule cell neurons send signals only at specific times in the cycle of oscillations. This so-called “phase locking” is necessary if oscillations are to function as reference signals in temporal coding.
The precise, high-resolution recording from granule cells necessary for these discoveries was possible only through technological innovations by Pernía-Andrade and Jonas, as previously no equipment was available to record synaptic signals in active rats in such high resolution. They are the result of a collaboration with the Miba machine shop, IST Austria’s electrical and mechanical SSU (Scientific Service Unit). Adapting commercially available equipment and custom-designing tools, Pernía-Andrade, Jonas and Todor Asenov, manager of the Miba machine shop, produced the first tools for precise biophysical analysis in active rats. This research is therefore not only a scientific advance but also represents a significant technological and conceptual progress in the quest to understand neuronal behavior under natural conditions.
(Source: ist.ac.at)