NRSC 4132 Blog

The response of a brain while listening to music is very different than the response of the brain to many other types of stimuli. While observing a scene there is no direct way to see how the brain is processing the image. Many different part of the brain must integrate the cloudy points of stimulation (or lack of stimulations,) pattern recognition, and memory among other things for the person to perceive what it is they are looking at. It is a very subjective experience that is difficult for a neuroscientist to analyze. Sound on the other hand (especially simple rhythmic sound) is often very directly observable by many available neurological measurements including EEGs. This has recently been the center of much attention in neuroscience and had provided fodder for several books including This is Your Brain on Music by Daniel J. Levitin and Musicophelia by Oliver Sacks.
EEG studies of patient response to rhythmic beats is the focus of Tagging the Neuronal Entrainment to Beat and Meter from the Journal of Neuroscience published this July. This study tries to delineate how the human mind processes beats and meter in general. Previously many studies were done exploring how musical meter can create an expectation in the listener, you have probably experienced this yourself by tapping your foot to a song you?ve never heard before. Most music (maybe excluding some jazz and freeform types of music) follows some predictable pattern and our brains zero in on them (wonderful recognizers of pattern that they are.)The theory of resonance has been proposed to explain these observances hypothesizing that after certain exposure to the rhythmic beats (or music) large groups of neurons become ?entrained? and resonate at frequency correlating with the music?s beat. By altering the beats from what is expected scientists have studied what the call evoked potentials (or EPs.)
In the studies done in this particular article researchers at the Institute of Neuroscience of the Universite Catholique de Louvain in Brussels, Belgium had participants listen to a 2.4 Hz beat an imagine it as either a binary beat (1 2, 1 2, 1 2, as in a march) or ternary (1 2 3, 1 2 3, 1 2 3, like in a waltz.) As a control they had some participants listen to the beat but did not instruct them to image a particular meter. They then monitored the response of the participants? EEGs. The researchers found that EEGs showed increases in amplitude of subharmonic frequencies in the groups that were imagining the binary and ternary beats. That means in the control group they showed a strong 2.4 Hz signal the binary group showed strong 2.4 and 1.2 Hz signal and the ternary group showed strong 2.4, 1.6, and .8 Hz signals. This supports many of the previous research done on this topic showing that direct observation of the physical experience of music can be measured and quantified using existing mode of neurological research. This may open doors to understanding how the brain processes other types of stimuli and art in the future.