Why Music Is Number, Time, and Pitch in Space

Source: JS Bach's Original Manuscripts for Solo Violin Partitas and Sonatas

Number, space, and classical music are highly structured domains that are also characterized by certain regularities. Our intuitive ability to detect and process numerical magnitude, transform spatial relationships, and understand the temporal aspect of music can be boiled down to our ability to manipulate magnitude information that is modality-insensitive. The multimodal magnitude system that is responsible for multi-sensory and multimodal integration is instantiated by our intraparietal sulcus (IPS) (Walsh, 2003).

The Intraparietal Sulcus Is the Seat of the Multimodal Magnitude Processing and Integration Center of the Brain That Connects Space, Time, and the Temporal Aspect of Music.

Neuroimaging studies in the lab show that in several animal species (e.g., rats, chickens, and ourselves), there are neurons that are specifically attuned to numerical magnitude. These neuronal groups can be found in the intraparietal sulcus area in the parietal cortex of the brain. Some researchers elevated intraparietal sulcus (IPS) to the status of the seat of number sense (Dehaene, Spelke, Pinel, Stanescu, & Tsivkin, 1999; Schel & Klingberg, 2017).

Interestingly, IPS also activates when participants perform tasks that require manipulating spatial relationships (Bray, Almas, Arnold, Iaria, & MacQueen, 2015) (Silk, Bellgrove, Wrafter, Mattingley, & Cunnington, 2010). Perhaps the most intriguing finding in this area of research is one reported by Schäfer, Fachner, and Smukalla (2013), which indicates that the mere act of listening to music is sufficient in temporarily changing the representation of space and time in our brain. This finding suggests that number, space, and the temporal aspect of music are intricately intertwined in our brains.

Listening to Mozart May Temporarily Improve Our Ability to Perform Spatial Transformation, But Practicing a Musical Instrument Makes the Improvement Permanent—That Is, Instantiated by IPS.

Listening to classical music is not exactly the same experience as actively practicing an instrument. Therefore, “the Mozart effect,” which was noted by a research group, showed that just being exposed to a particular Mozart piano sonata (K448) for 10 minutes can temporarily induce a small increase in the listeners’ ability to reason spatially; however, that should not be confounded with a more robust finding that has been consistently replicated across multiple research groups.

According to those studies, long-term musical training, and in particular, practicing a musical instrument, is positively associated with a more long-lasting improvement in performance on tasks involving manipulating spatial relationships in imagined two- and three-dimensional space. Spatial reasoning is a strong predictor of STEM learning outcomes from early childhood to young adulthood. We can therefore infer from this body of works that the cognitive advantage conferred by music training across number, space, and temporal aspects of music may be due to a shared multimodal magnitude processing center that is modality-insensitive and is substantiated by the IPS (Skagerlund, Karlsson, & Träff, 2016; Walsh, 2003).

Beyond the Temporal Aspect: Transposing a Piece of Music Across Different Key Areas Can Also Activate the IPS.

One may think that the link between number, music, and space is limited to the extent that processing temporal magnitude is relevant in decoding a piece of music. However, the story does not end here. Beyond the temporal aspect, pitch also plays a vital role in comprehending a piece of music. However, in what way does our IPS support pitch processing?

According to Foster and Zatorre (2010), transposing a musical composition across different key areas activates the right IPS of both musically trained and untrained participants. Furthermore, a whole-brain voxel-wise regression analysis of brain oxygenation level-dependent signal showed that performance in pitch transformation is positively associated with activities in the right IPS. This study expanded the notion that “Music Is Number in Space” to “Music Is Number, Time, and Pitch in Space” via a general-purpose magnitude processing center (Gennari, Dehaene, Valera, & Dehaene-Lambertz, 2023).