Music mnemonics aid Verbal Memory and Induce Learning - Related Brain Plasticity in Multiple Sclerosis

Abstract

Recent research on music and brain function has suggested that the temporal pattern structure in music and rhythm can enhance cognitive functions. To further elucidate this question specifically for memory, we investigated if a musical template can enhance verbal learning in patients with multiple sclerosis (MS) and if music-assisted learning will also influence short-term, system-level brain plasticity. We measured systems-level brain activity with oscillatory network synchronization during music-assisted learning. Specifically, we measured the spectral power of 128-channel electroencephalogram (EEG) in alpha and beta frequency bands in 54 patients with MS. The study sample was randomly divided into two groups, either hearing a spoken or a musical (sung) presentation of Rey's auditory verbal learning test. We defined the "learning-related synchronization" (LRS) as the percent change in EEG spectral power from the first time the word was presented to the average of the subsequent word encoding trials. LRS differed significantly between the music and the spoken conditions in low alpha and upper beta bands. Patients in the music condition showed overall better word memory and better word order memory and stronger bilateral frontal alpha LRS than patients in the spoken condition. The evidence suggests that a musical mnemonic recruits stronger oscillatory network synchronization in prefrontal areas in MS patients during word learning. It is suggested that the temporal structure implicit in musical stimuli enhances "deep encoding" during verbal learning and sharpens the timing of neural dynamics in brain networks degraded by demyelination in MS.

Keywords: alpha/beta oscillations; deep encoding; electroencephalogram; learning-related neural synchrony; musical mnemonic; verbal memory.

Figure 1

Rey’s auditory verbal learning test (RAVLT). There were 10 presentations of the same word list and one presentation of a new distractor word list. On each trial, subjects hear the full list of 15 words before being prompted to recall. Subjects are asked to perform free recall of the words again (without additional presentation) in two memory tests, M1 = immediate recall after the distractor list and M2 = recall after a 20 min delay and distractor task (D, distractor task).

Figure 2

Music enhances pair-wise word order learning and memory. X-axis: trial (learning trials 1–10, distractor trial “Dd,” and memory trials 1 and 2). The % of recalled word pairs in correct order (Y-axis) is the change relative to trial 1. Bars are standard error.

Figure 3

Music enhances memory for correct five word order sequences only during recall but not during acquisition. X-axis: trial (learning trial 1–10, distractor trial “D,” and memory trials 1 and 2). The % of recalled word sequences in correct order (Y-axis) is the change relative to trial 1. Bars are standard error. Bar graphs on right show % of correct word order for learning trials 6–10.

Figure 4

Music induces a different form of learning-related synchronization (LRS) during verbal learning in MS than non-musical learning. Left: music enhances bilateral frontal alpha₁ LRS. Right: music is associated with significantly reduced left posterior beta LRS than conventional spoken verbal learning (*denotes statistically significant difference between the groups).