CUNNINGHAM LAB
METHODS
Non-Invasive Brain Stimulation
Transcranial Direct Current Stimulation (tDCS)
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation modality that delivers diffuse, low level amplitudes of current (1-4 mA) to the surface of the cortex. Changes in corticospinal excitability can be observed using transcranial magnetic stimulation and neuroimaging in a polarity, intensity and duration dependent manner.
Repetitive Transcranial Magnetic Stimulation (rTMS)
rTMS operates on the principle of electromagnetic induction using an insulated wire placed on the scalp. The coil produces a brief and strong alternating current that induces a perpendicular spatially focused magnetic field. The magnetic field induces current, which passes unimpeded through the skull, resulting in depolarization or hyperpolarization of neurons in superficial cortices, depending on the frequency and intensity of stimulation.
Single and Paired Pulse Transcranial Magnetic Stimulation (TMS)
Single pulse and paired-pulse TMS operates in a similar manner to rTMS, except it is delivered at higher intensities resulting in generated action potentials in the cortex that propagate to the muscle resulting in a muscle twitch. We use single pulse and paired-pulse TMS to study neuroplasticity and neurophysiology of the brain.
Transcranial Direct Current Stimulation (tDCS)
Repetitive Transcranial Magnetic Stimulation (rTMS)
Single and Paired Pulse Transcranial Magnetic Stimulation (TMS)
Functional MRI (fMRI)
Resting State Functional MRI (rs-fMRI)
Diffusion Tensor Imaging (DTI)
Neuroimaging
Functional MRI (fMRI)
fMRI records region specific brain activity by comparing changes in blood flow during voluntary movement vs. rest. We use fMRI to detect adaptive neuroplasticity following neurological insult. We also use fMRI to define targets for non-invasive brain stimulation.
Resting State Functional MRI (rs-fMRI)
Rs-fMRI is an imaging technique that can characterize functional connectivity (FC) across widespread cortical networks. Rs-fMRI is based on the finding that in subjects at rest, there are spontaneous, low-frequency fluctuations in the fMRI blood oxygen-level dependent signal that exhibits a high degree of temporal correlation within specific brain networks. We use Rs-fMRI to detect distal effects of non-invasive brain stimulation via the connectome.
Diffusion Tensor Imaging (DTI)
DTI assesses the integrity of the white matter tracts based on the principle of water diffusion, where white matter normally has anisotropic diffusion. The magnitude and directionality of anisotropic diffusion yields DTI metrics of tract integrity. We use DTI to assess the integrity of white matter tracts following neurological insult as well as to assess structural connectivity via the connectome.