Multimodal characterisation of sensorimotor oscillations

Abstract

The studies in this project have investigated the ongoing neuronal network oscillatory activity found in the sensorimotor cortex using two modalities: magnetoencephalography (MEG) and in vitro slice recordings. The results have established that ongoing sensorimotor oscillations span the mu and beta frequency region both in vitro and in MEG
recordings, with distinct frequency profiles for each recorded laminae in vitro, while MI and SI show less difference in humans. In addition, these studies show that connections
between MI and SI modulate the ongoing neuronal network activity in these areas. The stimulation studies indicate that specific frequencies of stimulation affect the ongoing activity in the sensorimotor cortex. The continuous theta burst stimulation (cTBS) study demonstrates that cTBS predominantly enhances the power of the local ongoing activity.
The stimulation studies in this project show limited comparison between modalities, which is informative of the role of connectivity in these effects. However, independently these
studies provide novel information on the mechanisms on sensorimotor oscillatory interaction.
The pharmacological studies reveal that GABAergic modulation with zolpidem changes the neuronal oscillatory network activity in both healthy and pathological MI. Zolpidem enhances the power of ongoing oscillatory activity in both sensorimotor laminae and in
healthy subjects. In contrast, zolpidem attenuates the “abnormal” beta oscillatory activity
in the affected hemisphere in Parkinsonian patients, while restoring the hemispheric beta
power ratio and frequency variability and thereby improving motor symptomatology.
Finally we show that independent signals from MI laminae can be integrated in silico to resemble the aggregate MEG MI oscillatory signals. This highlights the usefulness of combining these two methods when elucidating neuronal network oscillations in the
sensorimotor cortex and any interventions.

Date of Award	21 May 2013
Original language	English
Supervisor	Ian M Stanford (Supervisor) & Stephen D Hall (Supervisor)