Dream Tanks

2 February 2008
The Rhythm (And Melody?) Of Life
By Rusty Rockets

Listening to music of any kind is an integral aspect of our lives, but is it a necessary aspect? There may be lots of folks who live without music, but scientific research shows there is much more to music than there is to other so-called leisure activities that we consider enjoyable.

Last week, a Systematic Review from The Cochrane Library revealed that therapists would soon be adding music to their arsenal of therapies to treat depression. One neuroscientist, Alan Harvey, goes as far as suggesting that music has an evolutionary basis in regard to the development of the human brain and how this development has subsequently shaped civilization. It's a suggestion that may explain why so many of us have such a passion for music, and why music therapies, at least anecdotally, seem to show so much promise.

At the recent Annual Australian Neuroscience Meeting in Hobart, Professor Harvey told attendees that music is not just something that sounds nice, but may have practical applications in fields such as education and therapy. "And yet it still seems a bit peripheral in medicine and in education because it's viewed as a luxury, something that's an add-on," he said on Australian Broadcasting Corporation radio recently. "I think [music is] actually core to our whole being, because it was there in the very beginning of us. Our founder population had music as well as language."

According to Harvey's theory, music is more than just an art and is essential to our make up. And he contends that it just could be responsible for the development of the human brain. But does that mean that music is still an essential aspect of our existence today, or – assuming that music once did have an evolutionary purpose – is music just a redundant evolutionary throwback, as some of Harvey's critics suggest? Answering questions such as this will probably comprise much of the book that Harvey, from the University of Western Australia, is planning to write about his controversial theory. A book that will show, one would hope, how music used in medicine has some foundation in science.

As Harvey freely admits, much of what he is proposing is nothing new; he's just piecing together an idea that cuts across a number of fields, such as evolution, neuroscience, and anthropology. As such, there are other researchers looking into how music can reveal insights, or be of practical benefit, in their particular field. Interestingly, many researchers have found that both music and language are inextricably linked in a fundamental way. In a study released in September of last year, Northwest University researchers wrote that music training has an all-encompassing holistic effect on how the nervous system processes sight and sound. As a result, the researchers reasoned that music training might be more important to verbal communication ability than other techniques, such as phonics.

"Audiovisual processing was much enhanced in musicians' brains compared to non-musician counterparts, and musicians also were more sensitive to subtle changes in both speech and music sounds," said Nina Kraus, Professor of Communication Sciences and Neurobiology and director of Northwestern's Auditory Neuroscience Laboratory. "Our study indicates that the high-level cognitive processing of music affects automatic processing that occurs early in the processing stream and fundamentally shapes sensory circuitry."

By identifying these multi-sensory traits peculiar to musicians, the researchers found that brain alterations resulting from exposure to music training affects the same communication skills required for both speaking and reading. "Musicians have a specialized neural system for processing sight and sound in the brainstem, the neural gateway to the brain," said lead author Gabriella Musacchia. But it was already well known that the pathway for multi-sensory processing originates in the brainstem, which is an evolutionary primeval part of the brain that has always been considered unmalleable. But in an exciting new development, the Northwestern researchers found that the brainstem exhibits much more plasticity than previously thought, and that it acts as a common pathway for both music and speech.

As a result, the researchers suggest that musical training could enhance literacy skills among children, or even help those with literacy disorders. "The study underscores the extreme malleability of auditory function by music training and the potential of music to tune our neural response to the world around us," said Kraus. It also begs the question of whether there is some merit to playing music to newborns. Furthermore, the Northwestern study provides some hope in regard to Alan Harvey's music theory, which claims that our link to music has evolutionary underpinnings. Previous findings show that children with literacy disorders also have brainstem transcription errors, which would suggest that Harvey might indeed be on the right track.

We need look no further than the tone-deaf, or amusic individuals, for further evidence that there is certainly a link between music and language processing in the brain. While your partner or family member may sound like a cat being strangled in the shower, they're at least enjoying their own musical mayhem. For someone who really is tone-deaf – roughly 4 percent of the population – music cannot be perceived in the way it is intended, nor create music themselves – music's just noise, and they find no pleasure in it at all.

Using neuroimaging, researchers from the Montreal Neurological Institute of McGill University found that amusic individuals had more gray matter in particular regions (namely the right interior frontal gyrus and the right auditory cortex) associated with processing musical pitch than did people who are not tone-deaf. "Overall, behavioral evidence indicates that congenital amusia is due to a severe deficit in the processing of pitch information. However, until now, very little was known about the neural correlates of this disorder," says lead author Dr. Krista Hyde.

Interestingly, Hyde's findings on musical disorders are also linked to a literacy disorder. "Specifically, we found that tone-deaf individuals had a thicker cortex (or gray matter) in particular brain regions known to be involved in auditory and musical processing. This parallels with what has been observed in the learning disability dyslexia, in which the cortex is thicker in areas of the brain involved in reading ability."

From these studies we have seen that music is not only integral to human enjoyment, but that music is linked to fundamental aspects of our cognitive make-up. In this respect, the multi-sensory training that music provides us with can be considered a vital bridge between how we perceive our environment and how we communicate what we experience to others. Perhaps this is why enjoying music with others can often be such a unifying experience.

28 February 2008
This Is Your Brain On Jazz
by Kate Melville

Using functional magnetic resonance imaging (fMRI), two scientists have discovered that when jazz musicians improvise, their brains turn off areas linked to self-censoring and inhibition, and turn on those that let self-expression flow. The joint research, using musician volunteers from the Johns Hopkins University's Peabody Institute, sheds light on the creative improvisation that artists and non-artists use in everyday life, the researchers say.

Reporting their findings in Public Library of Science (PLoS) ONE, the scientists, from the Johns Hopkins University's School of Medicine and the National Institute on Deafness and Other Communications Disorders (NIDCD), describe their curiosity about the possible neurological underpinnings of the almost trance-like state jazz artists enter during spontaneous improvisation.

"When jazz musicians improvise, they often play with eyes closed in a distinctive, personal style that transcends traditional rules of melody and rhythm," says Johns Hopkins' Charles J. Limb. "It's a remarkable frame of mind, during which, all of a sudden, the musician is generating music that has never been heard, thought, practiced or played before. What comes out is completely spontaneous."

Though many recent studies have focused on understanding what parts of a person's brain are active when listening to music, Limb says few have actually delved into brain activity while music is being spontaneously composed. Curious about his own "brain on jazz," he and a colleague, Allen R. Braun, of NIDCD, devised a plan to view in real time the brain functions of musicians improvising.

For the study, they recruited six trained jazz pianists and designed a special keyboard to allow the pianists to play inside a fMRI machine. Because fMRI uses powerful magnets, the researchers designed the unconventional keyboard with no iron-containing metal parts that the magnet could attract.

After recording baseline brain scans while the subjects played scales and memorized pieces of music, Limb and Braun then analyzed the brain scans as the musicians improvised their own tunes. Since the brain areas activated during memorized playing are parts that tend to be active during any kind of piano playing, the researchers subtracted those images from ones taken during improvisation. Left only with brain activity unique to improvisation, the scientists saw strikingly similar patterns, regardless of whether the musicians were doing simple improvisation on the C-major scale or playing more complex tunes with the jazz quartet.

The scientists found that a region of the brain known as the dorsolateral prefrontal cortex, a broad portion of the front of the brain that extends to the sides, showed a slowdown in activity during improvisation. This area has been linked to planned actions and self-censoring, such as carefully deciding what words you might say at a job interview. Shutting down this area could lead to lowered inhibitions, Limb suggests.

The researchers also saw increased activity in the medial prefrontal cortex, which sits in the center of the brain's frontal lobe. This area has been linked with self-expression and activities that convey individuality, such as telling a story about yourself. "Jazz is often described as being an extremely individualistic art form. You can figure out which jazz musician is playing because one person's improvisation sounds only like him or her," says Limb. "What we think is happening is when you're telling your own musical story, you're shutting down impulses that might impede the flow of novel ideas."

Limb notes that this type of brain activity may also be present during other types of improvisational behavior that are integral parts of life for artists and non-artists alike. For example, he notes, people are continually improvising words in conversations and improvising solutions to problems on the spot. "Without this type of creativity, humans wouldn't have advanced as a species. It's an integral part of who we are," Limb says.

In research that may lead to new therapies for children with autism and Asperger's syndrome, researchers from Northwestern University have found the first biological evidence that musical training enhances an individual's ability to recognize emotion in speech.

Reporting the findings in the European Journal of Neuroscience, the study's lead author Dana Strait explained that the more years of musical experience musicians possessed and the earlier the age they began their music studies increased their nervous systems' abilities to process emotion in sound. "Quickly and accurately identifying emotion in sound is a skill that translates across all arenas, whether in the predator-infested jungle or in the classroom, boardroom or bedroom," she noted.

The study involved measuring brainstem processing of three acoustic correlates (pitch, timing and timbre) in musicians and non-musicians to a scientifically validated emotion sound. The 30 subjects were right-handed men and women with and without music training who were between the ages of 19 and 35.

Study participants were asked to watch a subtitled nature film to keep them entertained while they were hearing, through earphones, a 250-millisecond fragment of a distressed baby's cry. Sensitivity to the sound, and in particular to the more complicated part of the sound that contributes most to its emotional content, was measured through cranial electrodes.

The researchers found that the musicians' brainstems lock onto the complex part of the sound known to carry more emotional elements but de-emphasize the simpler (less emotion conveying) part of the sound. This was not the case in non-musicians.

In essence, musicians more economically and more quickly focus their neural resources on the important - in this case emotional - aspect of sound. "That their brains respond more quickly and accurately than the brains of non-musicians is something we'd expect to translate into the perception of emotion in other settings," Strait said.

The authors of the study also note that the acoustic elements that musicians process more efficiently are the very same ones that children with language disorders, such as dyslexia and autism, have problems encoding. Strait suggests that musical training might help promote emotion processing in these populations.

In memory of the infamous and mysterious "H.M."–who sadly passed away last Tuesday–we re-post this elderly article from the archives. R.I.P., H.M. This article was originally published on 06 June 2007.

"I don't remember things," Henry explained to the unfamiliar female interviewer. She seemed very curious about how he spends a typical day, and about what he had eaten for breakfast, but his efforts to summon the information from his mind were fruitless. He could easily answer her questions regarding his childhood and early adult years, but the indefinite expanse of time since then was bereft of memories. In fact, from moment to moment Henry feels almost as though he has just awakened from a deep sleep, with the fleeting remnants of a dream always just beyond his grasp. Each experience, dull or dramatic, evaporates from his memory within a few dozen heartbeats and leaves no trace.

For over fifty years Henry has lived with anterograde amnesia, a form of profound memory loss which prevents new events from reaching his long-term memory. As a result his only memories are those he possessed prior to his amnesia, and the small window of moments immediately preceding the present.

The amnesia frequently depicted in fiction is a very rare retrograde variety known as dissociative fugue, where one's identity and all memories prior to the pivotal event are compromised. In contrast, anterograde amnesia does not deprive the sufferer of their identity, their past, or their skills; it merely prevents new memories from forming. As a consequence one's final memories are frozen in perpetuity, often accompanied by a constant sensation that one has just awoken from an "unconscious" state which filled the intervening time.

Henry's handicap is the unintended result of experimental brain surgery performed in 1953. In his late teens the highly intelligent student began to experience frequent grand mal seizures, characterized by loss of consciousness, muscle spasms, and rigidity. The frequency of these epileptic events increased to the point that he was stricken with spontaneous episodes of unconsciousness every few minutes. After exploring every other avenue known to contemporary medicine, Dr. William Scoville administered a radical resection of the man's medial temporal lobes in a desperate bid to reclaim some quality of life for young Henry. In that respect the experimental operation was a success– the patient's severe seizures were reduced dramatically after the operation– however the surgeon was distressed to discover that the removal of the hippocampi had stripped Henry of his ability to form new memories.

The location of the human hippocampiThe development seriously hindered Henry from pursuing a normal life, but due to his condition he quickly became the world's most famous subject in the study of the human brain. His real identity is a closely kept secret to this day, and he is referred to in medical literature by only his initials, "H.M." However unfortunate, H.M.'s handicap helped to propel memory research beyond the realm of the philosophical for the first time in history. Earlier efforts to explore memory had been limited to animal studies, where scientists deliberately damaged various regions of lab animals' brains to monitor any loss of memory functions. Such experiments were not only unpleasant for the animals, but frustratingly inconclusive for the researchers.

H.M. has been described as a friendly and articulate man with a higher-than-average IQ, sporting a charming personality in spite of his condition. Now in his early eighties, he still vividly recalls events from his childhood such as the stock market crash of 1929, but he is stricken with renewed grief every time he learns of his mother's death. The grief is short-lived, however, as the substance of the news soon slips from the feeble grasp of his "working memory." In an interview with researchers, he described the sensation:

Like most anterograde amnesiacs, Henry experienced a degree of retrograde amnesia as well, blurring the details of the months leading up to the fateful operation.

Similar cases of anterograde amnesia have appeared over the years, often caused by Korsakoff's Syndrome, a thiamine (vitamin B1) deficiency brought on by chronic alcoholism, malnutrition, eating disorders, or poisoning. This strongly suggests that thiamine is necessary to maintain the memory-writing features of the brain. Some abnormal viral infections can also produce the affliction, as is the case with a famed music expert named Clive Wearing. His ability to store memories was destroyed by a rogue infection of the herpes simplex 1 virus which attacked his brain's hippocampus rather than triggering the typical cold sores. Other known causes include brain tumors, oxygen deprivation, and dementia-related diseases such as Alzheimer's. In each instance it is found that the hippocampi have been compromised, indicating that these small structures are vital in laying down long-term memories. The hippocampus does not seem to play a role in recollection, however, since existing memories remain accessible.

Though anterograde amnesiacs are blocked from storing new information, researchers were astonished to discover that subjects are nonetheless capable of mastering new and complex tasks over time. Subjects who repeatedly practice skills such as backwards writing or guitar-playing can demonstrate measurable improvement, though in each instance the subject believes that he or she is attempting the task for the first time. This insight cast serious doubt upon the long-held belief that all memory is stored in a common mental reservoir. It also demonstrated that procedural memory– the "how to" memory of motor skills– is not governed by the exact same circuitry as episodic memory (autobiographical events) and semantic memory (general knowledge and facts). A diagram of one of Henry M's living spaces, and his depiction of it three years after moving out.Additionally, some patients have experienced the Tetris Effect hours or days after playing the game during experiments; they describe vivid dreams of falling Tetris shapes though they possess no conscious memory of the game's existence.

A neuroscientist named Suzanne Corkin has been following Henry's M.'s progress for about forty-three years, but each time she introduces herself he greets her as though he is meeting her for the first time. One one occasion, however, a nurse mentioned to Henry that "Dr. Corkin" had been asking about him, and he responded by asking, "Suzanne?" Though he could not say who she was, he had somehow managed to associate her first and last name.

Over the years a modest amount of semantic information has actually managed to seep into Henry's long-term memory, suggesting that his brain may be struggling to find alternate pathways with sporadic success. He knows that a president named John Kennedy was assassinated in 1963, and he can draw a roughly accurate diagram of a home where he lived for a few years following his surgery. Henry seems untroubled by the elderly face which stares back at him from the mirror, suggesting that he is unsurprised by the notion that decades that have passed since his life-changing operation. When asked what he thought about how he looked, he responded matter-of-factly, "I'm not a boy." He also seems to have learned that his memory is broken and that scientists are studying him to discover more about the human mind. Once, when asked whether he is happy, Henry responded "Yes" without hesitation. He followed with, "the way I figure it is, what they find out about me helps them to help other people."

Small talk with H.M. tends to be a bit repetitive, but occasionally revealing. During a visit to the Massachusetts Institute of Technology to conduct memory tests, Dr. Corkin asked Henry if he knew where he was as they strolled down a nondescript corridor. "Why of course," he replied with a grin, "I'm at MIT!"

Taken aback, Dr. Corkin asked, "How do you know that?"

Laughing, Henry pointed at a nearby student wearing an MIT sweater. "Got you that time!"

Not only did the event demonstrate his intact sense of humor, but it showed that his powers of deduction are unhindered by his memory malady. On another occasion Henry was asked what he does to try to remember things. "Well," he replied with a chuckle, "That I don't know ’cause I don't remember what I tried."

A scene from MementoIn a rare example of scientific correctness in Hollywood, the reality of anterograde amnesia was depicted with reasonable accuracy in the 2001 film Memento. The filmmakers applied the concept of reverse chronology to mimic the effects of the condition, allowing viewers to share in the protagonist's confusion regarding prior events.

Owing to his unfortunate ailment Henry M. will never be able to understand the inestimable gift he has given to the field of neurology. The amnesic octogenarian presently resides in a Connecticut nursing home, where even today he continues to help researchers to coax secrets from the human mind. Furthermore, Henry's lifelong contribution to science will not cease upon his death; he and his court-appointed guardian have agreed to donate his brain to science so that neurologists may one day examine the offending lesions in detail.

Though science still possesses a poor understanding of memory's machinations, Henry and other sufferers of anterograde amnesia have provided a considerable number of indispensable clues. Their unwitting contributions will not be soon forgotten.

27 March 2008
Brain Has Sixth Sense For Calories
by Kate Melville

The latest issue of the journal Neuron carries news of a "sixth sense" that scientists say can detect calories in food without the involvement of our regular taste sensors.

In the experiments, the researchers genetically altered mice to remove their sweet taste receptor cells, making them "sweet-blind." The research team then performed behavioral tests in which they compared normal and sweet-blind mice in their preference for sugar solutions (sucrose) and those containing the non-caloric sweetener sucralose. The researchers found that the sweet-blind mice showed a preference for calorie-containing sugar water that did not depend on their ability to taste.

In analyzing the brains of the sweet-blind mice, the researchers showed that the animals' reward circuitry was switched on by caloric intake, independent of the animals' ability to taste. Those analyses showed that levels of the brain chemical dopamine, known to be central to activating the reward circuitry, increased with caloric intake. Also, electrophysiological studies showed that neurons in the food-reward region, called the nucleus accumbens, were activated by caloric intake, independent of taste.

Interestingly, the researchers found that a preference for sucrose over sucralose developed only after ten minutes of a one-hour feeding session and that neurons in the reward region also responded with the same delay.

"We showed that dopamine-ventral striatum reward systems, previously associated with the detection and assignment of reward value to palatable compounds, respond to the caloric value of sucrose in the absence of taste receptor signaling," the researchers noted. "Thus, these brain pathways do not exclusively encode the sensory-related hedonic impact of foods, but might also perform previously unidentified functions that include the detection of gastrointestinal and metabolic signals."

The finding that the brain's reward system is switched on by this "sixth sense" machinery could have implications for understanding the causes of obesity. For example, the findings suggest why high-fructose corn syrup, widely used as a sweetener in foods, might contribute to obesity. It may be that fructose produces stronger activation of the reward system and that removing high-fructose corn syrup as a sweetener will curb some desire for these products.