Subcortical Plasticity Following Perceptual Learning in a Pitch Discrimination Task

Abstract

Practice can lead to dramatic improvements in the discrimination of auditory stimuli. In this study, we investigated changes of the frequency-following response (FFR), a subcortical component of the auditory evoked potentials, after a period of pitch discrimination training. Twenty-seven adult listeners were trained for 10 h on a pitch discrimination task using one of three different complex tone stimuli. One had a static pitch contour, one had a rising pitch contour, and one had a falling pitch contour. Behavioral measures of pitch discrimination and FFRs for all the stimuli were measured before and after the training phase for these participants, as well as for an untrained control group (n=12). Trained participants showed significant improvements in pitch discrimination compared to the control group for all three trained stimuli. These improvements were partly specific for stimuli with the same pitch modulation (dynamic vs. static) and with the same pitch trajectory (rising vs. falling) as the trained stimulus. Also, the robustness of FFR neural phase locking to the sound envelope increased significantly more in trained participants compared to the control group for the static and rising contour, but not for the falling contour. Changes in FFR strength were partly specific for stimuli with the same pitch modulation (dynamic vs. static) of the trained stimulus. Changes in FFR strength, however, were not specific for stimuli with the same pitch trajectory (rising vs. falling) as the trained stimulus. These findings indicate that even relatively low-level processes in the mature auditory system are subject to experience-related change.

Development of subcortical speech representation in human infants

“…Mice that are reared in the presence of repetitive clicks do not develop adult-like spectral tuning of IC neurons compared to mice who are reared in normal acoustic environments (Sanes and Constantine-Paton, 1985). Modulation of FFR responses has been demonstrated in humans with training (Carcagno and Plack, 2011) and with enhanced access to the signal through the use of an assistive listening device (Hornickel et al, 2012). Therefore, the early representation of low frequencies may arise from greater fetal exposure to sound in this frequency range.…”

A Little Goes a Long Way: How the Adult Brain Is Shaped by Musical Training in Childhood

“…We predicted that musical training during childhood leads to more robust neural processing of sound later in life. Our predictions were based on evidence that auditory brainstem responses (ABRs) to complex sounds are sensitive to the lifelong musical experience (Kraus and Chandrasekaran, 2010), language you speak (Krishnan et al, 2005;Krishnan and Gandour, 2009), the instrument you play , early and extensive bilingual experience (Krizman et al, 2012), and short-term auditory training (Song et al, 2008(Song et al, , 2012Carcagno and Plack, 2011;Chandrasekaran et al, 2012).…”

Subcortical encoding of sound is enhanced in bilinguals and relates to executive function advantages

“…The auditory brainstem response to complex sounds (cABR), a measure of auditory encoding strength and fidelity, provides a biological snapshot of the putative role of bottom-up and top-down processes that shape experience-dependent plasticity (24,25). Indeed, the cABR is malleable with training, whether relatively short in duration (26,27) or more protracted, such as lifelong experience with tonal languages or musicianship (28,29,30). Interestingly, musicians also demonstrate advantages in cognitive processing (i.e., attention and memory) that mirror those seen in bilinguals (31,32); and, in lifelong musicians, these advantages correlate with enhanced neural processing of sound, as measured by the cABR (28,29,33).…”