Age-related differences in laterality of cortical activations in swallowing

The present study examined age differences in neural lateralization patterns during swallowing and three related tasks, using functional magnetic resonance imaging (fMRI). Ten healthy right-handed young adults (mean age = 21.7 years, SD = 2.1 years) and nine healthy elders (mean age = 70.2 years, SD = 3.9 years) were scanned in a 3-T MRI head scanner. Participants were visually cued to "prepare to swallow," "swallow," "tap your tongue," and "clear your throat" in randomized order. Laterality preference for each task was examined within and between groups using region-of-interest (ROI) analyses in seven areas of the left and right primary sensorimotor and premotor cortices. Results of the within-group comparisons verified a more active role of the left premotor cortex in motor-cognitive planning of deglutition in both young and older adults and a more active role of selected areas of the right hemisphere during swallowing in young adults. Greater variability was seen during tongue tapping and throat clearing in both groups. Finally, as people age the cortical hemispheric control of swallowing seems to start becoming more symmetrical/bilateral, which may indicate neural compensatory mechanisms of the aging brain commonly seen for other motor and cognitive functions.