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INTRODUCTION Music has the ability to ensnare us all, not only with its mellifluous tones and rhythmic beats, but with its academic intrigue as to why and how it has such power. How does music affect us? To enjoy a song is to crawl inside its layered patterns and let the sound take over your mind; it is a process of seduction. An upset man can be seduced to tranquility, a lucid man can lose his sanity; religious or political views can be glorified and sadness can seem sexy. Music can be used for mating, communication, artistic expression, motivation, and the apotheosis of essentially anything. Throughout these behavioral affects, there is an underlying neurological process responding to the aforementioned type of aurally perceived pattern. This has been the source of many debates, essentially among evolutionary psychologists and neurologists who at first were baffled as to why a series of patterns of resonant frequencies can have so much power. Why are we so attracted to Resonance ? There are millions of different sounds we could have found beautiful, but resonance is what all musical creatures have agreed upon. Whales, birds, and humans all have decided on resonance and the resulting patterns of resonance that we are all familiar with (Gray, 2001). MUSIC IN THE ANIMAL KINGDOM Whales use music primarily for communication; its sounds are not only beautiful but are distinct and correspond to the origins of the whale pod. This distinctiveness implies environmental factors in the composition of these songs, but the universality implies a natural aspect. As is usual in such cases, it is most likely a mixture of the two. Birds use their songs primarily as a mating device. Evolutionary scientists have theorized that this is not directly beneficial to the species as song is actually a waste of energy and catches the attention of any predators in the area. If this is focused upon, song seems like an awful idea, however, it is now commonly thought that song functions to raise the natural selection bar for these birds of song. A bird must be in excellent health and must have developed properly in order to create a song worthy of attracting a mate, and only the most adept birds can sing and evade the consequential danger of predators drawn to its song (Gray, 2001). Whales and Birds are two of the most Phylogenetically complex and neurologically advanced groups of animals on earth, so the fact that they possess song should not be too surprising. That being said, the two most famous and popularly thought of as intelligent creatures have been left out of this: dolphins and chimpanzees. Dolphins possess language, but no real song, just a click-click-whine, with no real melody, while chimpanzees and other simians can be taught sign language, they have never been shown to learn music. THE BRAIN For and/or Birds ? Pitch We, as humans, love Resonant Frequencies ; they are present in all wave forms in physics, but when they are Aurally perceived we call them keys or pitches. In western music there are twelve chromatic Pitch Classes , which can be represented in many ways. In eastern music there are more notes than in the west. For instance, in western music there is only one interval between a C and a C sharp; but in India this is a large jump and there are many notes in between what we call a C and a C sharp. Each of these Pitch es can be arranged into Chords , which occur in characteristic sequences throughout Western music. For example, after two or three of these often-used chords are heard in sequence, the sequence of chords can be satisfactorily resolved only by a limited number of expected chords. This is a particular area of interest, as even musical laymen can detect these chord patterns and recognize when a chord progression has not resolved "correctly". Janata et al A paper by Janata et al. studied the cortical organisation of tonal relationships, to examine whether the auditory regions of the brain are organised in a similar fashion to the visual cortex. Would there be an organized strip of cells which all activate specifically to an A minor key? Janata found that the tori in the brain reacted in a specific pattern at unique distances from each other for specific keys. The voxels in the rostromedial Prefrontal Gyrus also exhibited selectivity for different keys. However across scanning sessions the voxels were found to rearrange themselves, but maintained a dynamic topography. In other words, there is no set strip of cells which respond to specific frequencies, although there was some correlation during the same session, this was not found to be constant across many sessions. Petr Janata theorized that, unlike visual objects, with finite visual features and distinct edges, musical keys are “abstract constructs that share core properties”. Most of music is not in the individual keys, but in the intervals crossed in the process of going from key to key. Perhaps the dynamic organization of tonal relationships is what gives music its ethereal nature, or perhaps it is music’s inherent ethereal nature which causes its neural perception to be dynamically organized. Twin studies The comprehension of musical pitch has been found to have a genetic correlation in a study between Monozygotic Twins and Dizygotic Twins (Drayna, Dennis). The twins were given a “Distorted Tunes Test” and had to point out an incorrect pitch in a melody. This study is another indicator of the natural and inherent existence of music, which has (for some reason) been engrained in our minds. Rhythm Music itself can be broken down into three main components: rhythm, melody, and lyrics. All three of these contribute to a song, although some genre’s concentrate on one aspect or another. Techno tends to concentrate on the beat; vocal and new-age tend to focus on the Melody , while hip hop and folk music concentrate on the Poetry . Rhythm is found everywhere in life; the brain is not excluded from this generalization. The Circadian Rhythm seems to be on a time scale which is far too large to contribute to music. The beats per minute in a song have been known to affect heart rate, and (coincidentally?) fall roughly in the same range of a normal human heart beat. A fast song can make the heart beat faster, while a slower paced song can make the heart beat slower . It would be interesting to see if there are any connections from the Auditory Cortex (or anywhere in the auditory network) which connect to the medulla to regulate heart beat. Perhaps even from the ear directly to the Hypothalamus , analogous to the Retino-hypothalamic Tract . Gray and McCormick It has also been found that the brain has its own rhythm in several studies, one of which was by Charles Gray of UC Davis and another by David McCormick of Yale U. School of Medicine (Schechter 1996). The so-called “chatter cells” coordinate rhythmic firings of millions of cells in bursts around 30-60 hertz. The idea is that this may link anatomically distant neural structures and although it has not been directly tied to music, nothing relates more anatomically and functionally distant structures than the subject of this paper. It has been indicated that different parts of the auditory cortex are involved in processing rhythm, specifically the belt and parabelt areas of the Right Hemisphere . When individuals are preparing to tap out a rhythm of regular intervals (1:2 or 1:3) the “left frontal cortex, left parietal cortex, and right cerebellum are all activated”(Tramo, 2001). With more difficult rhythms such as a 1:2.5, more of the cortex and cerebellum are involved. Still, the structures involved in tonal comprehension and speech are better known than the rhythm and involve many distant structures. Tonality and emotion It has been indicated that the right auditory cortex a primary component for perceiving pitch, and parts of harmony, melody and rhythm (Tramo 2001). Janata found that there are tonally sensitive areas in the medial prefrontal cortex, the cerebellum, the Superior Temporal Sulci of both hemispheres and the Superior Temporal Gyri (which has a skew towards the right hemisphere). When unpleasant melodies are played, the Posterior Cingulated Cortex is activated, indicating a form of pain (Tramo, 2001). The right brain has also been found to be correlated with emotion, which can also activate areas in the cingluate in times of emotional pain, specifically social rejection (Eisenberger). This evidence, along with observations, has led many musical theorists, philosophers and neuroscientists to link emotion with tonality. This seems almost obvious; the tones in music seem like a characterization of the tones in human speech which indicate emotional content. The Vowels in the Phonemes of a song are elongated for a dramatic effect, and it seems as though speech tones and musical tones are one and the same. This would be the case, however, studies on Amusia suggest at least a slight separation between speech Tonality and musical tonality. Congenital amusics are individuals who are incapable of distinguishing between pitches, they are unmoved by dissonance and a wrong key on a piano never bothers them. They cannot be taught to remember a melody or to recite a song. This being said, they are still capable of hearing the tonality of speech, for example, they can tell the difference between “You speak French” and “You speak French?” when spoken. Perhaps this suggests some sort of linear organization in the right brain for comprehending tone, analogous to the left hemisphere’s linguistic organization. Knowing this, it would be interesting to see if amusics have a flatter Affect than a control, or if right brain damaged patients exhibit at least a partial amusia. It would also be interesting if anyone were to do a study to see if patients with Amygdala damage exhibit some form of amusia. It seems as though tonality and rhythm are the most important and unique components to music, but lyrics play an important part too. Linguistics and organization Linguistics has generally been attributed to the left side of the brain, especially to the famous Broca’s Area , and the left Planum Temporale within Wernicke’s Area . Evolutionary neurobiologists have made endocasts of the skulls of early humans and have shown that society developed right along side the Lateralization of the planum temporale to the left side. This area has been indicated in musical ability, linguistic ability and in word memory. Musicians have been shown to have significantly more developed left planum temporales, and have also shown to have a greater word memory (Chan et al.). Chan’s study controlled for age, grade point average and years of education and found that when given a 16 word memory test, the musicians averaged one to two more words above their non musical counterparts. Even though most scientists attribute this ability to the lateralization, or attribute the lateralization to this ability, it has been found that chimpanzees have the same lateralization as humans. Based on this evidence, the chimp should be able to have the linguistic ability associated with this. This is just another indication that there is much more needed to produce music than a left planum temporale. DEVELOPMENT Malyarenko played music in a background setting for a group of four year old preschoolers for a period of six months. The musical group had significantly greater Interhemispheric activity and range coherence than the control. Also, the musical four year olds were found to have greater left hemisphere intrahemispheric coherence (Strickland, 2001). Musicians have been found to have more developed anterior portions of the Corpus Callosum in a study by Cowell et al. in 1992 (Strickland, 2001). This was confirmed by a study by Schlaug et al in 1995 who found that classical musicians between the ages of 21 and 36 have significantly greater anterior corpora callosa than the non-musical control. Schlaug also found that there was a strong correlation of musical exposure before the age of seven greatly increases the size of the corpus callosum (Strickland, 2001). These fibers join together the left and right hemispheres and indicate an increased relaying between both sides of the brain. This suggests the merging between the spatial- emotiono-tonal processing of the right brains and the linguistical processing of the left brain. It has been thought that this large relaying across many different areas of the brain has contributed to music’s ability to aide in memory function. Memory Musical training has been shown to aid in Memory functions in many different ways. Although the exact neural mechanism of how it helps it not fully agreed upon, it could be a neural exercise of different parts of the brain which are involved in memory. Another idea is that it could form neural connections from different angles to a single memory and help to create different pathways for the recall of a single memory. Altenmuller et al studied the difference between active and passive musical instruction and found the results to be equally effective in the short term. However, it was found that over a longer period of time, the actively taught students retained much more information than the passively taught students. The actively taught students were also found to have greater cerebral cortex activation; this would indicate that the musically taught students were more effectively taught. It should also be noted that the passively taught students weren’t wasting their time; they, along with the active group, displayed greater left hemisphere activity which is typical in trained musicians (Strickland, 2001). There is also an anecdote of a woman with Chronic Dementia due to her age, she could not remember integral portions of her life such her place of birth, her place of residence for the majority of her life, or if she had had a short career singing on the radio. Despite this extreme dotage, she could remember every song she had sang perfectly (Skloot, 2002). It has also been indicated that simple melodies get “stuck” in our heads easier than more complex ones. Evolutionary Biologists theorized that simpler tunes helped the ancient profession of the Bard sing and remember oral histories. It has been shown that the more predictable the tune, the easier it is to get stuck in the head (Shouse, 2001). When subjects are asked to remember a song in their heads, the same parts of the brains light up except fainter and the primary auditory cortex is not activated as much. AUDITORY CORTICES The has been indicated in the processing of “harmonic, melodic and rhythmic patterns.”(Music, Maestro, please!, 2002). The Tertiary Auditory Cortex supposedly integrates everything into the overall experience of music (Music, maestro please! 2002). This aligns with the studies of people remembering a song in their minds; they do not perceive any sound, but experience the melody, rhythm and overall experience of music. By deduction, when the primary auditory cortex is activated without auditory input, this should cause a hallucination. The going belief is that whole experience of music actually does terminate in the tertiary auditory cortex, which unites everything into the full experience. If so, it would be interesting to study a subject without a tertiary auditory cortex. This would be very difficult to do as the tertiary cortex is simply a ring around the secondary, which is a ring around the primary AC. The power of music should not be underestimated. It is the neural triathlon, triggering an incredible concatenation of neural events, along with many parallel processes. The incredible, linguistic, emotional, rhythmic, mnemonic powers of music have been a great source of entertainment and functionality in both our modern and ancient human environments. There is little doubt that the discoveries of musical comprehension from a neurological standpoint have only just begun. |
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