Chapter 9~ The Music Instinct

   Daniel J. Levitin starts the chapter with a quote from cognitive scientist Steven Pinker. Pinker said music is a "pleasure-seeking behavior that exploits pleasure channels that evolved to reinforce an adaptive behavior." Pinker goes on to say music is useless and human life would remain the same if music vanished. He believes music does not help humans reach goals such as, reproduction. Daniel J. Levitin disagrees with Pinker and gives evidence to support his argument. He defines the theory of evolution and points out the statement, "survival of the fittest" is an oversimplification of evolution. Organisms must do two things in order to be successful and fit. Fitness is based on one's reproductive success. Thus, an organism must successfully reproduce and pass its genes on to its offspring. The second thing is that the organisms' offsprings must be viable meaning they must survive and reproduce their own offsprings. This leads into Daniel J. Levitin's first piece of evidence. Natural selection will select towards features of organisms that will make the organism more attractive to possible mates because an organism must mate to pass on its genes. Darwin believed music played a role in sexual selection. He said music is used to charm and woo prospective mates. Darwin also believed that music was like a peacock's tail, which is an example of sexual dimorphism, which is used to impress mates. Such features' only purpose is to make the organism more attractive to mates. Geoffrey Miller, a cognitive physiologist , compares Darwin's ideas to modern society. Miller states that musicians show two things that are signs of sexual fitness. The first sign is that musicians show their good physical health. The second sign is that professional musicians have the resources to support another human being. This can also be seen in other examples from modern society. Wealthy people tend to show off their luxurious life to show potential mates that they have more than enough resources and to show their overall sexual fitness. Daniel J. Levitin suggests that creativity has been selected by evolution as an indication of sexual fitness. In a study to see the effect of creativity  on sexual selection, women were studied to see the type of men they preferred. The results showed that women preferred men who were creative but poor to men who were rich but had average creativity. Daniel J. Levitin makes two more points to support his idea. He says that if music is nonadaptive, then people who love music would be at an evolutionary disadvantage. The second point he makes is that music would not be practiced today if it had no adaptive value. Humans would not practice music then because it would be a waste of time and energy. Many cognitive scientists believe music preceded speech communication. They think music helped humans' ancestors prepare for speech communication. They think music has also helped humans refine their motor skills, paving the way for the development of muscle control which is required for speech communication. People like Pinker think music is only performed as a spectator activity. According to Levitin, music has only become a spectator activity in the last five hundred years. The evidence Daniel J. Levitin presents shows that music is more than a spectator activity and is useful in human life.

Peacock's tails are used to impress potential mates

   This Is Your Brain On Music by Daniel J. Levitin explains how music affects the human brain and why music is important. Daniel J. Levitin provides extensive details to support his statements and shows both sides of arguments regarding music and neural theory. He also adds his personal experiences to make the book more than just constant facts being piled on the reader. Daniel J. Levitin also explains music theory and neural theory so that the reader understands the two theories though the reader is not a professional on the topics. The book provides a good understanding of how music affects the human brain and ties all the concepts together well. I would recommend this book to others because of the overall knowledge the book provides to the reader.

Chapter 6~ After Dessert, Crick Was Still Four Seats Away from Me

   Music with a pulse is generally what humans listen to. Pulse within music generally is regular and evenly spaced. The pulse in music causes humans to create expectations in the piece of music they are listening to. Composers use pulse to set up expectations in a piece and then deviate from the expectations to move the listener emotionally. Composers also subdivide the regular beat, accenting certain notes differently than others. Groove is a strong momentum created from beat divisions that rhythmically drives the song. Groove is usually a subtle feature of a song and is best when it does not have a regular pulse. Composers also change the pulse subtlety by changing the dynamics of a song to reflect the emotions of humans. Dynamics consists of how loud or soft a musician should play, tempo changes, and crescendos and decrescendos. The brain uses feature extraction to create a schema or a model of a constant pulse in a song. This can also be called metrical extraction. The brain will then know when a piece of music deviates from the constant pulse whether it be through dynamics or the subdivision of beats. Violations of expectations is what moves humans emotionally when listening to a song.

Different Note Possibilities to Subdivide the Beat

    The cerebellum's functions are timing and the coordination of movements. The cerebellum is the part of the brain that keeps track of the beat to create a schema. Through the studies of Jeremy Schmahmann, it has been concluded that the cerebellum contains many connections to the human emotional centers of the brain, the amygdala and frontal lobe. The question that followed this discovery was,"what is the connection between movement and emotion." Daniel J. Levitin had the opportunity to sit down with Francis Crick and discuss this question. Francis Crick told him, "Look at the connections." Daniel J. Levitin conducted several experiments to measure and analyze the interaction of different brain regions with each other. He discovered that listening to music caused brain regions to become activated in a set order. The first region that was activated was the auditory cortex. The auditory cortex processed the components of the sound. Then the frontal regions of the brain were activated, processing musical structure and producing expectations. A network of regions called the mesolimbic system was activated last, causing the nucleus accumbens to be activated. The cerebellum and basal ganglia were active throughout the process. As a result, dopamine levels increased in the nucleus accumbens and the cerebellum helped regulate emotion because of its connections to the frontal lobes and mesolimbic system.

   Music is a way to improve people's moods. Music imitates some aspects of vocal communication. It activates some of the same regions of the brain that vocal communication does. It also activates regions that are involved with motivation, reward, and emotion. When listening to music, the brain is constantly updating its expectations of what will come next in the song. The cerebellum, through its connections, causes humans to feel delight or happiness when it updates its expectations after a song deviates from the cerebellum's previous expectations. Humans also feel joy when their expectations are correct and the expected beats are played in a given song. The way human react to music is based purely on connections between the different brain regions. A single song can activate the oldest and newest parts of the brain and can activate the regions in the back of the brain, all the way to the front of the brain.

Chapter 5~ You Know My Name, Look Up the Number

   Daniel J. Levitin poses the question of why can music trigger memories in humans that seem to be lost. Memories are encoded in groups of neurons and with the right cue, it will cause the memory to be retrieved. The more a memory is accessed, the easier it is to retrieve that memory later on. A song can be a cue that accesses memories, thus making the music move the person listening in a certain way because humans' memory systems are closely linked to the humans' emotional systems. Tune recognition involves neural computations interacting with memory. The brain extracts features that remain constant from each listening of a particular piece of music to perform these computations. When trying to remember a memory, the brain undergoes a process similar to perceptual completion in which it fills in the missing information. For example, if someone is recounting a dream, they will not remember each detail, so they begin fabricating information to finish the story. This activity takes place in the left side of the brain. There are two views on how humans preserve memories. The constructivist view is that the function of a memory is to ignore irrelevant details, while preserve the gist. The record-keeping view is that a memory is like a video camera that records each and every detail accurately.  There is evidence that supports both views, but according to Daniel J. Levitin neither one is correct and there is no theory that is correct at the moment.

   Humans have categories for all things whether they be living or inanimate. Music is categorized into different genres based on the musical structure of a piece. Some songs have elements of different genres, but they are still categorized under a certain genre. For example, a song might have elements of heavy metal like guitar riffs, but it is categorized as pop because the song resembles a pop song overall. Songs are categorized into genres based on the prototypical songs for musical categories. Daniel J. Levitin gives the example of choosing colors. When someone asks to choose the color red out of various shades of the color, one would choose the best example of red. There are three scenarios that organisms must deal with that are based on categorization. The first is that objects that appear similar are different. Objects may create similar or identical patterns of stimulation on humans' eardrums, retinas, taste buds, or touch sensors that cause humans to think the objects are the same. For example, an apple on a tree is different than an apple in someone's hand, but the two are different. The second scenario is that objects are identical though they might appear different. Looking at an object from different viewpoints might make the object appear as two different objects. The human brain has to extract information from the different viewpoints to create a unified representation of the object. The third scenario is that though objects are different, they are from the same category. For example, a red apple is different from a green apple, but both are apples. These three scenarios use the sensory surfaces to gather information for analysis to which adaptive behavior is dependent on. The concept of categorization allows listeners, composers, and performers to know the elements of a genre that a song of that genre should have. This gives the human brain expectations of what should happen in the music. When the music deviates from the expectation, it moves people and causes them to feel different emotions.

   How do songs get stuck in people's heads? Neural mechanisms that underlie perception of music and memory for music called ear worms. The neural circuits that represent a song get stuck in "playback mode" or plays back over and over again. Small pieces of songs get stuck rather than whole songs. Simple songs and commercial jingles are more likely to get stuck rather than complex songs. The fragment of a song that gets stuck is usually fifteen to thirty seconds. Songs that suit a person musical preference are also more likely to get stuck in their head. People with obsessive-compulsive disorder are often troubled with ear worms and have to take medication. When people sing the songs that get stuck in their heads, they usually sing the songs with accurate pitch and tempo, according to Daniel J. Levitin's studies. Songs have an overall sound with specific pitches and rhythms. Human memory remembers the overall soundscape of a song that allows humans to sing the song with accurate pitch and tempo.

Chapter 3 ~Behind The Curtain

   The chapter opens with the difference between the mind and the brain. According cognitive scientists,  the part of each human that embodies their thoughts, hopes, desires, memories, beliefs, and experiences is the mind while the brain is an organ of the body. Cognitive scientists compare this to a computer. The brain is like the computer's hardware and the mind is like the programs that run on the hardware. Scientists take this one step further stating different minds can arise from very similar brains like different programs can run on the same hardware. The idea of dualism from René Descartes states the mind and brain are two separate things. According to Dualists, the mind of a human already exists before birth and the brain is an instrument of the mind that helps it carry out its functions. The brain has networks of interconnected neurons that compute information sent to them and then combine their computations which leads to thoughts, decisions, perceptions and consciousness. The average brain has one hundred billion neurons with a number of connection possibilities. Today, scientists believe the sum total of a human's thoughts, beliefs, and experiences is represented in electrochemical activity in the brain. The mind cannot function without the brain, but the brain can still exist without the mind, just thoughtless. Particular regions of the brain are responsible or involved with certain functions of the body. Neuropsychological investigation allows scientists to map out areas of the brain's areas of function. For example, the result of strokes, tumors, head injury, or other trauma, cause damage to an area of the brain and leads to the loss of a mental or bodily function. When a specific area of the brain is damaged and the loss of a specific mental or bodily function occurs as a result in hundreds of similar cases, scientists can conclude that the specific area of the brain is involved with the function that was lost.  Damage to the Wernicke's area, just above and behind the left ear, causes difficulty in understanding spoken language. Damage to the motor cortex, the region at the top of the head, causes difficulty to finger movement and damage to the hippocampal complex, region in the center, prevents the formation of new memories. The frontal lobes are connected to aspects of self and personality, but scientists have yet to create a map of the personality traits that are distributed widely throughout the brain because of the complex regional differentiation of structure and function in the brain.

   Music activity affects most regions of the brain. Music begins with the cochlear nuclei, the brain stem, and the cerebellum, It then travels up to the auditory cortices. When a person tries to sing along with a song, they use their hippocampus and inferior frontal cortex. When a person taps along with the music, they use the timing circuits in their cerebellum. Performing music with any instrument involves the frontal lobes, the motor cortex, and the sensory cortex. Listening to lyrics or remembering them involves the temporal and frontal lobes. The emotions humans experience from music involves the amygdala.

Kaniza Illusion

   The human brain fills missing information as a result of the human perceptual system. This information could be visual or auditory. For example, in the Kaniza illusion, we see a white triangle on top of the black one. The human perceptual system completes the information that is not there. This action is an evolutionary adaptation because the perceptual system can fill in missing information that can help make quick decisions in life or death situations. The auditory system has its own perceptual system. Richard Warren, a cognitive psychologist, recorded a sentence and then cut out a piece of the sentence. The missing piece was replaced with static. People who heard the sentence said they heard both the sentence and static during the missing portion of the sentence. The auditory system of those people filled in the missing information. The auditory system does this by a process called feature extraction. The brain extracts low level features from audio. Low level processing refers to the perception of build block characteristics of a sensory stimulus. The brain does this by using specialized neural networks that breakdown the signal caused by the stimulus into information regarding pitch, timbre, spatial location, loudness, and tone. High level processing uses the information from the low level processing to create an image to fill in the missing information. This is what allows human to expect what will come next in the music. The human auditory system generates this information based on four factors. The first is the music that has already come before in the piece of music we are listening to. The second is what the brain remembers will come next if the music is familiar. The third is what the brain expects will come next if it has been exposed to a familiar style of music. The last factor is any additional information given, such as an unexpected movement by the performer. The auditory system's perceptual system helps humans expect what will happen in the music. These expectations are a factor in how humans react to a piece of music.

   After birth, the brain has a period of rapid neural development in which new neural connections are formed. The brain reduces these connections to the ones that are used the most. This develops into the basis of human understanding of music. The human understanding of music is based on human experiences as well. Detectors in the brain use feature extraction to process the structure of scales and chords. This forms expectations of what will happen next in the music. These expectations determine how someone is moved by a piece of music and whether or not they like the style of the music. Musical expectations link music theory and neural theory to help scientists understand how music gives rise to patterns of neural activations.
 

Chapter 1~ What Is Music?

   The opening chapter explains music theory, defining key words necessary to know in order to better understand the novel. Daniel J. Levitin defines a set of key terms that are the basis to music and help explain other musical concepts. According to Levitin, pitch is the frequency of a particular tone and its relative position on the musical scale. Rhythm is defined as the duration and grouping of a series of notes. Tempo is the speed or pace of a particular piece. Contour is the overall shape of a melody. It only recognizes whether a note goes up or down and does not measure the amount of this change. Timbre is the distinct quality of sound produced by a particular instrument. Loudness refers to the amount of energy an instrument creates. These elements help one understand the concepts of meter, key, melody, and harmony. Meter is defined by Levitin as the way tones are grouped across time. The combination of rhythm and meter drive all music. Key refers the hierarchy that exists between the tones in a piece. Melody refers to the main theme of a piece. Harmony is a parallel to the melody and is chord progression that forms a background for the melody and forms expectations in a musical piece. Daniel J. Levitin emphasizes these terms and their importance in the first chapter because he uses them often in later chapters.

   Daniel J. Levitin then goes more in depth about pitch because music is defined by a set of pitch relations. He poses the question of what defines pitch. Frequency is the measuring device of pitch and if an object creates a sound with a frequency that can not be heard, then it is not truly a pitch. Daniel J. Levitin continues with how pitch conveys different emotions in a musical piece. Humans generally associate different pitches with different emotions. For example, low notes usually convey sadness while high notes usually convey excitement or happiness. Daniel J. Levitin then explains how humans distinguish different pitches. Hair cells in the basilar membrane of the inner ear are frequency selective. At one end of the basilar membrane, low-frequency pitches excite the hair cells and high-frequency pitches excite the hair cells at the other end. In the middle, medium-frequency excite hair cells. The frequency selective hair cells create what is called a tonotopic map because the different frequencies are spread across the membrane. Once there is activity detected in the membrane, an electrical signal is sent to the auditory cortex which also has a tonotopic map. Like the auditory cortex and basilar membrane, the brain responds to different pitches in different areas. Daniel J. Levitin also talks about timbre in greater detail. Timbre is the result of the overtone series which is the numbered order of overtones from the fundamental frequency. Timbre is important because it is what humans use to distinguish between two things whether they are living or nonliving. For example, timbre helps human recognize the bark of dog from the purr of a cat. Timbre also allows humans to detect emotions in another person's voice based on the timbre of their voice. Daniel J. Levitin compares timbre to the way a painter uses shading to change the overall emotion or feeling of a painting and to separate different shapes. Like painters, composers use timbre to convey a particular emotion and to separate different melodic shapes.  Daniel J. Levitin uses the first chapter to explain music theory to provide the basis for his novel.