Where is music processed in the brain

According to Aniruddh D. Patel of the Neurosciences Institute in San Diego, imaging findings suggest that a region in the frontal lobe enables proper construction of the syntax of both music and language, whereas other parts of the brain handle related aspects of language and music processing.

Imaging studies have also given us a fairly fine-grained picture of the brain's responses to music. These results make the most sense when placed in the context of how the ear conveys sounds in general to the brain [ see box on opposite page ]. Like other sensory systems, the one for hearing is arranged hierarchically, consisting of a string of neural processing stations from the ear to the highest level, the auditory cortex.

The processing of sounds, such as musical tones, begins with the inner ear cochlea , which sorts complex sounds produced by, say, a violin, into their constituent elementary frequencies. The cochlea then transmits this information along separately tuned fibers of the auditory nerve as trains of neural discharges.

Eventually these trains reach the auditory cortex in the temporal lobe. Different cells in the auditory system of the brain respond best to certain frequencies; neighboring cells have overlapping tuning curves so that there are no gaps.

Indeed, because neighboring cells are tuned to similar frequencies, the auditory cortex forms a frequency map across its surface [ see box on page 41 ]. The response to music per se, though, is more complicated. Music consists of a sequence of tones, and perception of it depends on grasping the relations between sounds.

Many areas of the brain are involved in processing the various components of music. Consider tone, which encompasses both the frequencies and loudness of a sound. At one time, investigators suspected that cells tuned to a specific frequency always responded the same way when that frequency was detected. But in the late s David Diamond, Thomas M. McKenna and I, working in my laboratory at the University of California, Irvine, raised doubts about that notion when we studied contour, which is the pattern of rising and falling pitches that is the basis for all melodies.

We constructed melodies consisting of different contours using the same five tones and then recorded the responses of single neurons in the auditory cortices of cats. We found that cell responses the number of discharges varied with the contour. Responses depended on the location of a given tone within a melody; cells may fire more vigorously when that tone is preceded by other tones rather than when it is the first.

Moreover, cells react differently to the same tone when it is part of an ascending contour low to high tones than when it is part of a descending or more complex one. These findings show that the pattern of a melody matters: processing in the auditory system is not like the simple relaying of sound in a telephone or stereo system. Most research has focused on melody, but rhythm the relative lengths and spacing of notes , harmony the relation of two or more simultaneous tones and timbre the characteristic difference in sound between two instruments playing the same tone are also of interest.

Studies of rhythm have concluded that one hemisphere is more involved, although they disagree on which hemisphere. The problem is that different tasks and even different rhythmic stimuli can demand different processing capacities. For example, the left temporal lobe seems to process briefer stimuli than the right temporal lobe and so would be more involved when the listener is trying to discern rhythm while hearing briefer musical sounds.

The situation is clearer for harmony. Imaging studies of the cerebral cortex find greater activation in the auditory regions of the right temporal lobe when subjects are focusing on aspects of harmony.

Timbre also has been assigned a right temporal lobe preference. Patients whose temporal lobe has been removed such as to eliminate seizures show deficits in discriminating timbre if tissue from the right, but not the left, hemisphere is excised. In addition, the right temporal lobe becomes active in normal subjects when they discriminate between different timbres.

Brain responses also depend on the experiences and training of the listener. Even a little training can quickly alter the brain's reactions. For instance, until about 10 years ago, scientists believed that tuning was fixed for each cell in the auditory cortex. Our studies on contour, however, made us suspect that cell tuning might be altered during learning so that certain cells become extra sensitive to sounds that attract attention and are stored in memory.

To find out, Jon S. Bakin, Jean-Marc Edeline and I conducted a series of experiments during the s in which we asked whether the basic organization of the auditory cortex changes when a subject learns that a certain tone is somehow important. Our group first presented guinea pigs with many different tones and recorded the responses of various cells in the auditory cortex to determine which tones produced the greatest responses. Next, we taught the subjects that a specific, nonpreferred tone was important by making it a signal for a mild foot shock.

The guinea pigs learned this association within a few minutes. We then determined the cells' responses again, immediately after the training and at various times up to two months later. The neurons' tuning preferences had shifted from their original frequencies to that of the signal tone. Thus, learning retunes the brain so that more cells respond best to behaviorally significant sounds.

This cellular adjustment process extends across the cortex, editing the frequency map so that a greater area of the cortex processes important tones. One can tell which frequencies are important to an animal simply by determining the frequency organization of its auditory cortex [ see box on opposite page ].

The retuning was remarkably durable: it became stronger over time without additional training and lasted for months. These findings initiated a growing body of research indicating that one way the brain stores the learned importance of a stimulus is by devoting more brain cells to the processing of that stimulus.

Although it is not possible to record from single neurons in humans during learning, brain-imaging studies can detect changes in the average magnitude of responses of thousands of cells in various parts of the cortex.

In Ray Dolan and his colleagues at University College London trained human subjects in a similar type of task by teaching them that a particular tone was significant.

The group found that learning produces the same type of tuning shifts seen in animals. The long-term effects of learning by retuning may help explain why we can quickly recognize a familiar melody in a noisy room and also why people suffering memory loss from neurodegenerative diseases such as Alzheimer's can still recall music that they learned in the past. Even when incoming sound is absent, we all can listen by recalling a piece of music.

Think of any piece you know and play it in your head. Where in the brain is this music playing? In Andrea R. Halpern of Bucknell University and Robert J. Zatorre of the Montreal Neurological Institute at McGill University conducted a study in which they scanned the brains of nonmusicians who either listened to music or imagined hearing the same piece of music. Another area in the cerebrum called the dorsolateral frontal cortex is stimulated when hearing music to keep the song in working memory and bring up images that are associated with the sounds, and to visualize the music when playing it, according to the National Institute of Neurological Disorders and Stroke.

The motor cortex is also an area of the cerebrum. It helps to control body movements such as when playing a musical instrument, by processing visual and sound cues. The cerebellum is located at the back of the head, below the cerebrum.

The National Institute of Neurological Disorders and Stroke explains that this organ is the second largest in the brain and is a vital control center for reflex actions, balance, rhythm and coordinating skeletal muscle movement.

The cerebellum helps to create smooth, flowing and integrated movements when hearing or playing music. It works in harmony with other parts of the brain to affect rhythmic movement in the body when moving in response to the music. The cerebellum allows a performer to move the body in accordance to reading or visualizing music when playing a musical instrument, as described by the Center for Neuroskills. Our vocalizations, and our ability to perceive their nuances and subtlety, co-evolved. In a UCLA study, neurologists Istvan Molnar-Szakacs and Katie Overy watched brain scans to see which neurons fired while people and monkeys observed other people and monkeys perform specific actions or experience specific emotions.

If you are watching an athlete, for example, the neurons that are associated with the same muscles the athlete is using will fire. This mirror effect goes for emotional signals as well. When we see someone frown or smile, the neurons associated with those facial muscles will fire.

Visual and auditory clues trigger empathetic neurons. Corny but true: If you smile you will make other people happy. We feel what the other is feeling—maybe not as strongly, or as profoundly—but empathy seems to be built into our neurology.

It has been proposed that this shared representation as neuroscientists call it is essential for any type of communication.

The border between what you feel and what I feel is porous. That we are social animals is deeply ingrained and makes us what we are. We think of ourselves as individuals, but to some extent we are not; our very cells are joined to the group by these evolved empathic reactions to others.

And when a singer throws back his head and lets loose, we understand that as well. We have an interior image of what he is going through when his body assumes that shape. We anthropomorphize abstract sounds, too. Simple feelings—sadness, happiness and anger—are pretty easily detected.

Footsteps might seem an obvious example, but it shows that we connect all sorts of sounds to our assumptions about what emotion, feeling or sensation generated that sound. The UCLA study proposed that our appreciation and feeling for music are deeply dependent on mirror neurons. When you watch, or even just hear, someone play an instrument, the neurons associated with the muscles required to play that instrument fire.

Do you have to know how to play the piano to be able to mirror a piano player? Edward W. Large at Florida Atlantic University scanned the brains of people with and without music experience as they listened to Chopin. As you might guess, the mirror neuron system lit up in the musicians who were tested, but somewhat surprisingly, it flashed in non-musicians as well.

The UCLA group contends that all of our means of communication—auditory, musical, linguistic, visual—have motor and muscular activities at their root. By reading and intuiting the intentions behind those motor activities, we connect with the underlying emotions. Our physical state and our emotional state are inseparable—by perceiving one, an observer can deduce the other.

People dance to music as well, and neurological mirroring might explain why hearing rhythmic music inspires us to move, and to move in very specific ways. Music, more than many of the arts, triggers a whole host of neurons. Multiple regions of the brain fire upon hearing music: muscular, auditory, visual, linguistic. Oliver Sacks wrote about a brain-damaged man who discovered that he could sing his way through his mundane daily routines, and only by doing so could he remember how to complete simple tasks like getting dressed.

Melodic intonation therapy is the name for a group of therapeutic techniques that were based on this discovery. Mirror neurons are also predictive.

When we observe an action, posture, gesture or a facial expression, we have a good idea, based on our past experience, what is coming next. But most folks catch at least a large percentage of them.