Aberrant cortico-subcortical functional connectivity among women with poor motor control: toward uncovering the substrate of hyperkinetic perseveration.

OBJECTIVE

Hyperkinetic perseveration (HKP) refers to perseverative repetition of rudimentary motor output. Although HKP is known to be associated with brain injuries and certain neurodegenerative disorders (primarily those involving the frontal lobes and the basal ganglia), an increased tendency to exhibit HKP is also commonly associated with apparently normal aging (i.e., in the absence of known neuropathology). The purpose of the present study was to examine anomalies in brain functioning associated with HKP tendencies in a non-injured brain.

METHOD

The present study examined functional MRI connectivity patterns associated with HKP in a sample of 24 "young" (ages 25-35 years) and 20 "old" (ages 65-75 years) healthy community dwelling women. Participants performed a motor learning task (the Push-Turn-Taptap task: PTT) known to elicit HKP. On a separate day, participants were scanned on a Siemens 3T Trio MR scanner with a 12-channel head coil, while performing a block-design motor sequence learning task that was designed to be a scanner analog for the PTT task. Cortico-subcortical connectivity patterns involving two subcortical regions of interest (putamen and thalamus) and three cortical regions (sensory-motor cortex, Brodmann Area 6, inferior frontal gyrus) were examined.

RESULTS

Older participants exhibited a higher rate of HKP compared to younger participants. Age-related HKP was associated with hemispheric asymmetry marked by a relatively stronger right-hemisphere cortico-subcortical connectivity involving the sensory-motor cortex and, to a lesser extent, Brodmann Area 6. These patterns were distinct from connectivity patterns associated with aging alone.

CONCLUSIONS

HKP is related to anomalies involving frontal-subcortical circuits. Future research should examine specific components of the basal-ganglia circuitry.