Table 1
Neurological imaging and measurement techniques
| Technique | Role of Technique | Advantages | Limitations |
|---|---|---|---|
| Positron Emission Tomography (PET) | Three-dimensional functional imaging of a radioactive tracer (injected the body). | Reasonable spatial resolution. | Requires injection of radionucleotide, expensive (require full time staff & radionucleotide cost), restricted movement environment, not portable. |
| Functional Magnetic Resonance Imaging (fMRI) | Measure three-dimensional changes in cerebral blood flow overlaid on a magnetic resonance imaging brain map. | High spatial resolution. | Expensive (require full time staff), restricted movement environment, not portable. Reliant upon neurovascular coupling, which is the interpretation of the blood oxygen level dependent (BOLD) signal. Low temporal resolution. |
| Transcranial Magnetic Stimulation (TMS) | Sends a magnetic burst targeted toward a general anatomic region. | Non-invasive, can be used to elicit motor evoked potentials (MEPs) with measurable amplitude and latency using surface electromyography (EMG). | Requires high level of training to deliver, and interpret. Variability can be high depending on relative positions of coil, and participant. Low spatial resolution. |
| Magnetoencephalography (MEG) | Measures magnetic fields from cerebral sources. | High temporal resolution. | Expensive (require full time staff), requires high level of training to deliver, and interpret, restricted movement environment, not portable. |
| Electroencephalography – Surface (EEG) | Records spontaneous electrical activity from the central nervous system relative to a reference electrode. | High temporal resolution, records electrical responses concurrently with presentation of other stimuli. | Requires high level of training to deliver, and interpret. Surface recorded, and not time locked to external pre-cognitive stimuli, spatial resolution limited. |
| Somatosensory Evoked Potentials – Short Latency (SEPs) | Responses of PNS and CNS to time locked and consistent stimulation producing electrical activity as consistent measureable waveforms that can be averaged for clean interpretation. Measured using surface EEG. | Time locked to stimulus (consistent), early peaks are pre-cognitive in response to stimulation. | Requires high level of training to deliver, and interpret. Surface recorded, spatial resolution limited to peak interpretation. |
| Event Related Potentials (ERPs) | Brain response directly related to a sensory, motor or cognitive event. Waveforms are averaged by repeated exposure to the “event” or stimuli of interest. Measured using surface EEG. | High temporal resolution (<1 ms) | Poorly defined spatial resolution. Requires high level of training to deliver, and interpret. |
| Source Localization | Mathematical model for data de-convolution, allows for de-blurring of scalp EEG. | Improves EEG spatial resolution from a centimetre scale on the cortex to a millimetre scale. | Requires high level of level of training to deliver, and interpret |
| Standardized Weighted Low-Resolution Brain Electromagnetic Tomography (swLORETA) | Mathematical model used to determine the depth of source localization of EEG signals. | Improves EEG and Source Localization interpretation. | Requires high level of level of training to deliver, and interpret. |