Play it again, Sam: How the brain recognizes familiar music

Source:McGill University Summary:Research 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 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.Share This 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). Credit: Palmer, Mathias McGill University[Click to enlarge image] 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).Credit: Palmer, Mathias McGill University 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." This study was conducted within the framework of the European Erasmus Mundus Auditory Cognitive Neuroscience exchange program, in which North American researchers complete a research project in collaboration with a European laboratory for 6-12 months.

The Brain Processes Complex Stimuli More Cumulatively Than We Thought

The finding represents a new view of how the brain creates internal representations of the visual world. "We are excited to see if this novel view will dominate the wider consensus" said senior author Dr. Miyashita, who is also Professor of Physiology at the University of Tokyo's School of Medicine, "and also about the potential impact of our new computational principle on a wide range of views on human cognitive abilities." The brain recalls the patterns and objects we observe by developing distinct neuronal representations that go along with them (this is the same way it recalls memories). Scientists have long hypothesized that these neuronal representations emerge in a hierarchical process limited to the same cortical region in which the representations are first processed. Because the brain perceives and recognizes the external world through these internal images, any new information about the process by which this takes place has the power to inform our understanding of related functions, including knowledge acquisition and memory. However, studies attempting to uncover the functional hierarchy involved in the cortical process of visual stimuli have tried to characterize this hierarchy by analyzing the activity of single nerve cells, which are not necessarily correlated with neurons nearby, thus leaving these analyses lacking. In a new study appearing in the 12 July issue of the journal Science, lead author Toshiyuki Hirabayashi and colleagues focus not on single neurons but instead on the relationship between neuron pairs, testing the possibility that the representation of an object in a single brain region emerges in a hierarchically lower brain area. "I became interested in this work," said Dr. Hirabayashi, "because I was impressed by the elaborate neuronal circuitry in the early visual system, which is well-studied, and I wanted to explore the circuitry underlying higher-order visual processing, which is not yet fully understood." Hirabayashi and colleagues analyzed nerve cell pairs in cortical areas TE and 36, the latter of which is hierarchically higher, in two adult macaques. After these animals looked at six sets of paired stimuli for several months to learn to associate related objects (a process that can lead to pair-coding neurons in the brain), the researchers recorded neuron responses in areas TE and 36 of both animals as they again performed this task. The neurons exhibited pair association, but not where the researchers would have thought. "The most surprising result," said senior author Dr. Yasushi Miyashita "was that the neuronal circuit that generated pair-association was found only in area TE, not in area 36." Indeed, based on previous studies, which indicated that the number of pair-coding neurons in area TE is much smaller, the researchers would have expected the opposite. During their study, Miyashita and other team members observed that in region TE of the macaque cortex, unit 1 neurons (or source neurons) provided input to unit 2 neurons (or target neurons), which -- unlike unit 1 neurons -- responded to both members of a stimulus pair. "The representations generated in area TE did not reflect a mere random fluctuation of response patterns," explained Dr. Miyashita, "but rather, they emerged as a result of circuit processing inherent to that area of the brain." In area 36, meanwhile, members of neuron pairs behaved differently; on average, unit 1 as well as unit 2 neurons responded to both members of a stimulus pair. Neurons in area 36 received input from area TE, but only from its unit 2 neurons. Taken together, these findings lead the authors to hypothesize the existence of a hierarchical relationship between regions TE and 36, in which paired associations first established in the former region are propagated to the latter one. Here, area 36 represents the next level of a so-called feed forward hierarchy. The work by Hirabayashi and colleagues suggests that the detailed representations of objects commonly observed in the brain are attained not by buildup of representations in a single area, but by emergence of these representations in a hierarchically prior area and their subsequent transfer to the brain region that follows. There, they become sufficiently prevalent for the brain to register. The work also reveals that the brain activity involved in recreating visual stimuli emerges in a hierarchically lower brain area than previously thought. Moving forward, the Japanese research team has plans to expand upon this research, thus continuing to contribute to studies worldwide that aim to give scientists the best possible tools with which to obtain a dynamic picture of the brain. As a next step, the team hopes to further elucidate interactions between the various cortical microcircuits that operate in memory encoding. Dr. Miyashita has conjectured that these microcircuits are manipulated by a global brain network. Using the results of this latest study, he and colleagues are poised to further evaluate this assumption. "It will also be important to weave the neuronal circuit mechanisms into a unified framework," said Dr. Hirabayashi," and to examine the effects of learning on these circuit organizations." Equipped with their new view of cortical processing, the team also hopes to trace the causal chain of memory retrieval across different areas of the cortex. "I am excited by the recent development of genetic tools that will allow us to do this," said Dr. Miyashita. A better understanding of object representations from one area of the brain to the next will shed even greater light on elusive aspects of this hierarchical organ

Brain Frontal Lobes Not Sole Center of Human Intelligence, Comparative Research Suggests

May 13, 2013 — Human intelligence cannot be explained by the size of the brain's frontal lobes, say researchers.  Research into the comparative size of the frontal lobes in humans and other species has determined that they are not -- as previously thought -- disproportionately enlarged relative to other areas of the brain, according to the most accurate and conclusive study of this area of the brain.

It concludes that the size of our frontal lobes cannot solely account for humans' superior cognitive abilities.

The study by Durham and Reading universities suggests that supposedly more 'primitive' areas, such as the cerebellum, were equally important in the expansion of the human brain. These areas may therefore play unexpectedly important roles in human cognition and its disorders, such as autism and dyslexia, say the researchers.

The study is published in the Proceedings of the National Academy of Sciences (PNAS) today.

The frontal lobes are an area in the brain of mammals located at the front of each cerebral hemisphere, and are thought to be critical for advanced intelligence.

Lead author Professor Robert Barton from the Department of Anthropology at Durham University, said: "Probably the most widespread assumption about how the human brain evolved is that size increase was concentrated in the frontal lobes.
"It has been thought that frontal lobe expansion was particularly crucial to the development of modern human behaviour, thought and language, and that it is our bulging frontal lobes that truly make us human. We show that this is untrue: human frontal lobes are exactly the size expected for a non-human brain scaled up to human size.

"This means that areas traditionally considered to be more primitive were just as important during our evolution. These other areas should now get more attention. In fact there is already some evidence that damage to the cerebellum, for example, is a factor in disorders such as autism and dyslexia."

The scientists argue that many of our high-level abilities are carried out by more extensive brain networks linking many different areas of the brain. They suggest it may be the structure of these extended networks more than the size of any isolated brain region that is critical for cognitive functioning.

Previously, various studies have been conducted to try and establish whether humans' frontal lobes are disproportionately enlarged compared to their size in other primates such as apes and monkeys. They have resulted in a confused picture with use of different methods and measurements leading to inconsistent findings

Using Anticholinergics for as Few as 60 Days Causes Memory Problems in Older Adults

May 7, 2013 — Research from the Regenstrief Institute, the Indiana University Center for Aging Research and Wishard-Eskenazi Health on medications commonly taken by older adults has found that drugs with strong anticholinergic effects cause cognitive impairment when taken continuously for as few as 60 days. A similar impact can be seen with 90 days of continuous use when taking multiple drugs with weak anticholinergic effect.

The study of 3,690 older adults is among the first to explore how length of use of this group of drugs affects the brain. The study is available online in advance of publication in a print issue of Alzheimer's & Dementia, the journal of the Alzheimer's Association. The research was funded by a grant (R24MH080827) from the National Institute on Aging.

Anticholinergic drugs block acetylcholine, a nervous system neurotransmitter. Drugs with anticholinergic effects are sold over the counter and by prescription. Older adults commonly use over-the-counter drugs with anticholinergic effects as sleep aids and to relieve bladder leakage. Drugs with anticholinergic effects are frequently prescribed for many chronic diseases including hypertension, cardiovascular disease and chronic obstructive pulmonary disease.

A list of drugs noting their anticholinergic burden can be found on the Aging Brain Care website.

The Regenstrief Institute, IU Center for Aging Research and Wishard-Eskenazi Health researchers reported that continuously taking strong anticholinergics, like many sleeping pills or antihistamines, for only 60 days caused memory problems and other indicators of mild cognitive impairment. Taking multiple drugs with weaker anticholinergic effects, such as many common over-the-counter digestive aids, had a negative impact on cognition in 90 days.

"We found that a high anticholinergic burden -- either from one or multiple drugs -- plus two to three months of continuous exposure to that high burden approximately doubled the risk of developing cognitive impairment," said Noll Campbell, Pharm.D., study co-author and Regenstrief Institute investigator. "Millions of older adults are taking sleeping pills or prescription drugs year after year that may be impacting their organizational abilities and memory."

Dr. Campbell is also an IU Center for Aging Research scientist, a research assistant professor in the Department of Pharmacy Practice, Purdue University College of Pharmacy, and a clinical pharmacy specialist in geriatrics with Wishard-Eskenazi Health Services.

"While the link between anticholinergics and cognitive impairment has been reported by our group and others, the cumulative burden of anticholinergics was rather unexpected, as was the lack of a clear association between anticholinergic burden and dementia," said Regenstrief Institute investigator Malaz Boustani, M.D., MPH. Dr. Boustani, the senior author of the study, who is also associate director of the IU Center for Aging Research and an associate professor of medicine at IU School of Medicine. He sees patients at the Healthy Aging Brain Center at Wishard-Eskenazi Health.

"The fact that taking anticholinergics is linked with mild cognitive impairment, involving memory loss without functional disability, but not with Alzheimer's disease and other dementing disorders, gives hope. Our research efforts will now focus on whether anticholinergic-induced cognitive impairment may be reversible," Dr. Boustani said.

Alzheimer's Fuzzy Signals Into High Definition

 May 7, 2013 — Scientists at the Virginia Tech Carilion Research Institute have discovered how the predominant class of Alzheimer's pharmaceuticals might sharpen the brain's performance

17One factor even more important than the size of a television screen is the quality of the signal it displays. Having a life-sized projection of Harry Potter dodging a Bludger in a Quidditch match is of little use if the details are lost to pixilation.

The importance of transmitting clear signals, however, is not relegated to the airwaves. The same creed applies to the electrical impulses navigating a human brain. Now, new research has shown that one of the few drugs approved for the treatment of Alzheimer's disease helps patients by clearing up the signals coming in from the outside world.

The discovery was made by a team of researchers led by Rosalyn Moran, an assistant professor at the Virginia Tech Carilion Research Institute. Her study indicates that cholinesterase inhibitors -- a class of drugs that stop the breakdown of the neurotransmitter acetylcholine -- allow signals to enter the brain with more precision and less background noise.

"Increasing the levels of acetylcholine appears to turn your fuzzy, old analog TV signal into a shiny, new, high-definition one," said Moran, who holds an appointment as an assistant professor in the Virginia Tech College of Engineering. "And the drug does this in the sensory cortices. These are the workhorses of the brain, the gatekeepers, not the more sophisticated processing regions -- such as the prefrontal cortex -- where one may have expected the drugs to have their most prominent effect."

Alzheimer's disease affects more than 35 million people worldwide -- a number expected to double every 20 years, leading to more than 115 million cases by 2050. Of the five pharmaceuticals approved to treat the disease by the U.S. Food and Drug Administration, four are cholinesterase inhibitors. Although it is clear that the drugs increase the amount of acetylcholine in the brain, why this improves Alzheimer's symptoms has been unknown. If scientists understood the mechanisms and pathways responsible for improvement, they might be able to tailor better drugs to combat the disease, which costs more than $200 billion annually in the United States alone.

In the new study, Moran recruited 13 healthy young adults and gave them doses of galantamine, one of the cholinesterase inhibitors commonly prescribed to Alzheimer's patients. Two electroencephalographs were taken -- one with the drugs and one without -- as the participants listened to a series of modulating tones while focusing on a simple concentration task.

The researchers were looking for differences in neural activity between the two drug states in response to surprising changes in the sound patterns that the participants were hearing.

The scientists compared the results with computer models built on a Bayesian brain theory, known as the Free Energy Principle, which is a leading theory that describes the basic rules of neuronal communication and explains the creation of complex networks.

The theory hypothesizes that neurons seek to reduce uncertainty, which can be modeled and calculated using free energy molecular dynamics. Connecting tens of thousands of neurons behaving in this manner produces the probability machine that we call a brain.

Moran and her colleagues compiled 10 computer simulations based on the different effects that the drugs could have on the brain. The model that best fit the results revealed that the low-level wheels of the brain early on in the neural networking process were the ones benefitting from the drugs and creating clearer, more precise signals.

"When people take these drugs you can imagine the brain bathed in them," Moran said. "But what we found is that the drugs don't have broad-stroke impacts on brain activity. Instead, they are working very specifically at the cortex's entry points, gating the signals coming into the network in the first place."