Electrical Brain Imaging
This non-invasive technique records graded potentials from large populations of neurons via electrodes placed on the scalp.
What is electroencephalography (EEG)?
This imaging technique involves injecting a radioactive isotope to measure the uptake of specific molecules in the brain.
What is Positron Emission Tomography (PET)?
This technique uses two electrodes and a small battery-powered current to depolarize or hyperpolarize neurons under the scalp.
What is Transcranial Direct Current Stimulation (tDCS)?
This therapeutic technique involves surgically implanting an electrode to deliver electrical stimulation to deep brain structures, and is famously used to treat motor symptoms in Parkinson's disease.
What is Deep-Brain Stimulation (DBS)?
This imaging technique uses X-rays to create 3D images of the brain but is minimally sensitive to the contrast between grey and white matter.
What is computed tomography (CT)?
This type of analysis involves averaging many trials of EEG data that are time-locked to a specific stimulus or event.
What are event-related potentials (ERPs)?
This signal, measured by fMRI, is based on the difference in magnetic properties between oxygenated and deoxygenated hemoglobin.
What is the BOLD (Blood-Oxygenation Level Dependent) signal?
This technique relies on the principle of electromagnetic induction to pass a magnetic field through the skull, inducing a secondary electrical current in the brain.
What is Transcranial Magnetic Stimulation (TMS)?
These two highly specific techniques, used in animal models, allow researchers to control the activity of genetically targeted neurons with either light or a chemical compound.
What are Optogenetics and DREADDs (Chemogenetics)?
This non-invasive technique relies on measuring the magnetic properties of hydrogen protons after they are aligned by a strong magnetic field and perturbed by radiofrequency pulses.
What is Magnetic Resonance Imaging (MRI)?
This non-invasive method uses SQUIDs (superconducting quantum interference devices) to measure the magnetic fields produced by neuronal activity.
This is the characteristic, slow pattern of increased blood flow to an active brain region that is tracked by fMRI.
What is the Haemodynamic Response Function (HRF)?
Though carrying a stigma, this procedure involves the induction of a seizure and is one of the most effective treatments for treatment-resistant depression.
What is Electroconvulsive Therapy (ECT)?
A recent, highly successful DBS trial for depression targeted white matter tracts connected to this brain region.
What is the subgenual cingulate cortex (sgACC)?
This method visualizes the brain's white matter tracts by measuring the restricted diffusion of water molecules along axon bundles.
What is Diffusion-Weighted Imaging (DWI)?
This invasive technique involves placing an electrode array directly on the pial surface of the brain to record cortical local field potentials (LFPs).
What is Electrocorticography (ECoG)?
A key advantage of PET is the ability to create highly selective tracers to image specific targets, such as these neurotransmitter receptors.
What are dopamine receptors?
This emerging stimulation technique can target deep cortical and subcortical structures using ultrasonic waves.
What is Transcranial Focused Ultrasound (TfUS)?
This "N of 1" personalized approach for depression precision brain mapping to place surface electrodes at specific prefrontal targets to cure depression.
What is Personalized Adaptive Cortical Electrostimulation (PACE)?
Unlike standard MRI which images water, this specialized technique can measure the concentration of different brain metabolites and neurotransmitters.
What is Magnetic Resonance Spectroscopy (MRS)?
This is the most invasive electrical recording method, using probes inserted deep into brain tissue to record single-cell activity.
What are single-cell recordings (or depth electrodes)?
This type of fMRI measures intrinsic brain organization by analyzing spontaneous BOLD signal fluctuations while participants are not performing a task.
What is resting-state fMRI?
Unlike tDCS, TMS is powerful enough to directly induce these all-or-none neural signals.
What are action potentials?
In the above case study, this resting-state brain network was found to be particularly large, a finding that has been replicated in several other depression cohorts.
What is the "salience network"?
When a radiofrequency pulse is applied, the amount of time it takes hydrogen protons to return to the B0/longitudinal orientation is known as this type of 'decay' time.
What is longitudinal relaxation time (or T1 relaxation time)?
Unlike EEG, MEG is NOT sensitive to these neural sources.
What are radial dipoles?
What is "cognitive subtraction"?
This is thought of as the main advantage of ultrasonic neuromodulation relative to TMS and tDCS.
What is the ability to target deep structures directly?
This would be the main advantage of genetically targeted tools like optogenetics and DREADDs in future human trials.
What is the ability to target specific neural populations (i.e., highest level of 'circuit-specificity')?
The amount of time it takes for hydrogen protons to go out of phase after the application of a radiofrequency pulse is referred to as this type of decay time.
What is transverse relaxation time (or T2 relaxation)?