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.