Aberrant age-related alterations in spontaneous cortical activity in participants with cerebral palsy

Abstract

Introduction: Cerebral Palsy (CP) is the most common neurodevelopmental motor disability, resulting in life-long sensory, perception and motor impairments. Moreover, these impairments appear to drastically worsen as the population with CP transitions from adolescents to adulthood, although the underlying neurophysiological mechanisms remain poorly understood.

Methods: We began to address this knowledge gap by utilizing magnetoencephalographic (MEG) brain imaging to study how the amplitude of spontaneous cortical activity (i.e., resting state) is altered during this transition period in a cohort of 38 individuals with spastic diplegic CP (Age range = 9.80-47.50 years, 20 females) and 67 neurotypical controls (NT) (Age range = 9.08-49.40 years, Females = 27). MEG data from a five-minute eyes closed resting-state paradigm were source imaged, and the power within the delta (2-4 Hz), theta (5-7 Hz), alpha (8-12 Hz), beta (15-29 Hz), and gamma (30-59 Hz) frequency bands were computed.

Results: For both groups, the delta and theta spontaneous power decreased in the bilateral temporoparietal and superior parietal regions with age, while alpha, beta, and gamma band spontaneous power increased in temporoparietal, frontoparietal and premotor regions with age. We also found a significant group x age interaction, such that participants with CP demonstrated significantly less age-related increases in the spontaneous beta activity in the bilateral sensorimotor cortices compared to NT controls.

Discussion: Overall, these results demonstrate that the spontaneous neural activity in individuals with CP has an altered trajectory when transitioning from adolescents to adulthood. We suggest that these differences in spontaneous cortical activity may play a critical role in the aberrant motor actions seen in this patient group, and may provide a neurophysiological marker for assessing the effectiveness of current treatment strategies that are directed at improving the mobility and sensorimotor impairments seen in individuals with CP.

Keywords: beta; magnetoencephalography; neuroimaging; resting state; sensorimotor.

Figure 1

Main effects of age. Statistical maps thresholded with threshold-free cluster enhancement (TFCE) depict regions showing aging effects in the delta, theta, alpha, beta, and gamma bands. The corresponding scatter plots display relative power in percent units on the y-axis and age on the x-axis. The dots and trendline in each plot represent extracted values from each cluster peak per participant. (A) Delta (2–4 Hz) power decreased with advancing age in bilateral temporoparietal regions. (B) Theta (3–6 Hz) power decreased with advancing age in bilateral superior parietal regions. (C) Alpha (8–12 Hz) power increased with advancing age in bilateral temporoparietal regions. (D) Beta (15–29 Hz) power increased with advancing age in the left postcentral gyrus and right superior parietal regions. (E) Gamma (30–59 Hz) band power increased with advancing age with bilateral cluster peaks in premotor regions. The color bar next to each map shows the log transformed TFCE values.

Figure 2

Interaction effects of group and age. Scatter plots display relative beta power in percent units on the y-axis and age on the x-axis in bilateral left (A) and right (B) motor cortices. The blue circles and trendline represent NT controls, while the green circles and trendline represent participants with CP. In both regions, relative beta power increased in both groups, but with distinct slopes. The color bar between the two maps shows the scale of log transformed TFCE values. Extracted cluster peak average values are plotted for each participant in the graph.