Effects of Lifelong Musicianship on White Matter Integrity and Cognitive Brain Reserve.

There is a significant body of research that has identified specific, high-end cognitive demand activities and lifestyles that may play a role in building cognitive brain reserve, including volume changes in gray matter and white matter, increased structural connectivity, and enhanced categorical perception. While normal aging produces trends of decreasing white matter (WM) integrity, research on cognitive brain reserve suggests that complex sensory-motor activities across the life span may slow down or reverse these trends. Previous research has focused on structural and functional changes to the human brain caused by training and experience in both linguistic (especially bilingualism) and musical domains. The current research uses diffusion tensor imaging to examine the integrity of subcortical white matter fiber tracts in lifelong musicians. Our analysis, using Tortoise and ICBM-81, reveals higher fractional anisotropy, an indicator of greater WM integrity, in aging musicians in bilateral superior longitudinal fasciculi and bilateral uncinate fasciculi. Statistical methods used include Fisher's method and linear regression analysis. Another unique aspect of this study is the accompanying behavioral performance data for each participant. This is one of the first studies to look specifically at musicianship across the life span and its impact on bilateral WM integrity in aging.

L2 speech perception in noise: An fMRI study of advanced Spanish learners.

This experiment examined the neural correlates of second language (L2) speech perception in noise in advanced Spanish students. Participants completed a speech perception task in quiet and noise in their first language (L1 = English) and L2 during fMRI. Behavioral tests of L2 Spanish sentence recognition confirmed that advanced learners of Spanish can recognize sentences in quiet and in noise with an average of 85.45% and 74.43% accuracy, respectively. While listening to degraded sentences in the L2, both auditory and executive processing regions (specifically those of attention) were activated. While listening to L2 sentences in noise, learners focused on decoding the speech signal at the perceptual level, indicating a bottom-up processing strategy relying heavily on the signal's phonetic detail. During the processing of L1 in noise there was only significant activation in executive processing regions like the cingulate cortex and a region linked to lexical-semantic access (LIFG). In this case, participants appear to use a top-down strategy for sentence recognition, relying on lexical resources using a holistic strategy for perception. These findings suggest that L2 learners use fundamentally different perceptual strategies and neural circuits for understanding speech in noise in their L1 and L2.