Cortical activity during motor execution, motor imagery, and imagery-based online feedback Kai J. Miller, Gerwin Schalk, Eberhard E. Fetz, Marcel den Nijs, Jeffrey G. Ojemann, and Rajesh P. N. Rao Presenter: Ting-Yuan Huang Advisor: Chun-Yu Lin

Introduction Imagery has been shown to be crucial for motor skill learning in – Learning new skills – Relearning motion after neurological injury Motor imagery could play an important role in rehabilitation or prosthesis control like – Paraplegic individuals – Stroke patients – Amputate patients

Neuroimaging Direct activation related to electrical activity of the brain – Electroencephalography (EEG) – Magnetoelectroencephalography (MEG) Consequent haemodynamic response – Positron emission tomography (PET) – Functional magnetic resonance imaging (fMRI) – Functional near infrared spectroscopy (fNIRS) MEG PET NIRS

Introduction The areas involved in motor planning and motor execution – Medial supplemental motor area – Premotor cortex – Dorsolateral prefrontal cortex – Posterior parietal cortex

Introduction With EEG and MEG studies find – Primary motor cortex (motor imagery) – Lateral frontoparietal cortex (overlap between movement and imagery)

Electrocorticography (ECoG) Using electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral cortex

Electrocorticography (ECoG) ECoG is an invasive procedure (craniotomy), may be performed in the operating room – Intraoperative ECoG (during surgery) – Extraoperative ECoG (outside of surgery) Signals can characterize local cortical dynamics with very high spatiotemporal precision

Electrocorticography (ECoG) Potential power spectral density (PSD) – Low-frequency band (LFB) (8–32 Hz) – High-frequency band (HFB) (76–100 Hz)

Electrocorticography (ECoG) Movement – Low-frequency band (LFB) (8–32 Hz) Decrease in power – High-frequency band (HFB) (76–100 Hz) Increase in power ECoG to address the problem of imagery- associated cortical activity – Similar to movement in LFB & HFB – 25% of actual movement in cortical activity

Methods Eight subjects: – Underwent craniotomy – Placement 38 electrodes arrays for 5–7 days to localize seizure foci before surgery

Methods Three tasks – Interval-timed active motor movement – Interval-timed motor imagery – A cursor-to-target movement task To provide feedback on motor imagery

Movement task Simple and repetitive movements of – Hand – Tongue – Shoulder – Simple vocalization

Imagery task Imagining making identical movement rather than executing the movement – Cues Hand, Tongue, Shrug, Move for each movement modality – The imagery was kinesthetic rather than visual

Results Movements & Imagery: HFB LFB

Feedback task Selected a feedback feature used for online cursor control and imagine to move a cursor toward one target Hits or Miss Hits or Miss Rest & move the cursor to the other target move a cursor toward one target Active Idle & Passive Feedback

Feedback task 5-7 min for learning how to control the cursor Targets were presented in random order – Up/down – Left/right

Feedback task

Results Relative activation – Feedback > Movement > Imagery

Results

Discussion The spatially broad decrease in power in the LFB and spatially focal increase in power in the HFB were observed during imagery and movement When this same imagery was used to control a cursor in a simple feedback task, we found an augmentation of spatially congruent cortical activity, even beyond that found during movement