Enhanced Lexical Tone Learning in Musicians: Behavioral and Neural Evidence

We have conducted a series of experiments examining musicians’ ability to learn to use pitch in word identification and the possible underlying cortical mechanisms. Unlike English, most languages of the world, called tone languages, use pitch patterns (or lexical tones) to mark word meaning. We trained musicians and nonmusicians who are native English-speaking adults to identify a vocabulary of six English monosyllabic pseudo-words superimposed with three lexical tones (high-level, rising and falling pitch patterns), totaling 18 words (e.g., /pesh/ spoken with a high-level and rising pitch patterns mean ‘glass’ and ‘pencil,’ respectively). Learning to use pitch lexically is essential for mastering the vocabulary. We found that all subjects improved to a certain degree; however, musicians showed the most successful learning. Behavioral, neurophysiologic (hemodynamic responses measured before and after training), and neuroanatomic factors associated with learning were investigated. Behaviorally, musicians (and successful learners) showed better pitch pattern identification measured before training. Neurophysiologically, fMRI revealed increased activation in the auditory cortex in the successful learners even before training. Neuroanatomically, the gray matter volume of the left Heschl’s Gyrus was larger in the successful learners. Multiple regression analysis showed that these behavioral, neurophysiologic, and neuroanatomic factors combined significantly predicted how well a subject learned. After training, fMRI revealed fewer areas of activation in the successful learners relative to the less successful learners, suggesting learning-related cortical streamlining. Of note, the few areas of activation in the successful learners included the dorsal (but not ventral) auditory cortex. These results are discussed in the framework of the Reverse Hierarchy Theory of perceptual learning (Ahissar & Hochstein, 2004), focusing on how long-term exposure to pitch in one context (music) can result in efferent modulation of sensory encoding and attention weighting (Nosofsky, 1986; Goldstone, 1988) that ultimately facilitates the generalization of pitch processing and learning in another context (speech).

Investigators

Tyler Perrachione
Anil Roy

Patrick Wong

Collaborators

Cath Warrier (Northwestern University)
Virginia Penhune (Montreal Neurological Institute)
Todd Parrish (Northwestern University)
Robert Zatorre (Montreal Neurological Institute)

White label shows left HG label from (A) a representative successful learner and (B) a representative less successful learner.

Brain activation revealed by the Successful vs. Less Successful Learners (Post-Training Speech) contrast. Stronger activation for the successful and less successful learners are indicated by red and blue clusters, respectively.