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 HuangAdvisor: 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)

MEGPET

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

Rest & move the cursor to the other

target

move a cursor toward one

target

move a cursor toward one

target

ActiveActive Idle & PassiveIdle & Passive FeedbackFeedback

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