Electrophysiology

Electrophysiology measures voltage changes or electric current in brain cells and tissue of people with bipolar disorder.

Eye movement dysfunction

What is eye movement dysfunction? Smooth pursuit eye movement is a visual tracking reflex evoked by a smoothly moving target, usually elicited by stimuli presented on a computer monitor. The aim of the smooth pursuit reflex is to maintain the image of the moving target on the fovea, the region of the retina with the highest density of photoreceptors. The neural pathways involved in generating smooth pursuit are a complex network from the cortical visual pathways through to the brainstem ocular motor nuclei (III, IV and VI), and consequently an alteration in smooth pursuit performance may not in itself shed…

Mismatch negativity

What is mismatch negativity? Mismatch negativity (MMN) is an auditory event-related potential that is generated when a stimulus feature deviates from the regularity of previous auditory stimuli. This deviance can be a simple physical characteristic, such as tone duration, intensity, frequency or location; or more abstract presentation characteristics, such as a lower tone in a series of ascending tones. In this way, MMN generation relies on the creation of an auditory (echoic) memory trace for the preceding tones, in order to identify the subsequent deviance. MMN is thought to be an automatic, pre-attentional process and functions as an index of…

N170

What is the N170? The N170 wave is an event-related brain potential measured using electroencephalography. The N170 is a negative waveform that peaks at approximately 170 msec after stimulus presentation. It is observed at occipitotemporal sites and with greater amplitude over the right hemisphere. The N170 ERP is observed in response to a variety of facial stimuli, and so it may reflect a neural mechanism for detection of human faces. What is the evidence for N170 anomalies in people with bipolar disorder? Low quality evidence in unclear of N170 amplitude and latency changes in people with bipolar disorder compared to…

P300

What is the P300? The P300 wave is an event-related potential, measured using EEG. It is a spike in brain activity approximately 300ms following presentation of an infrequent target stimulus, which is alternated with more frequent standard stimuli to create an ‘oddball’ paradigm. The subject must respond only to the infrequent target stimulus. The amplitude of the P300 response is proportional to the amount of attentional resource devoted to the task and the degree of information processing required, while the latency is considered a measure of stimulus classification speed, unrelated to behavioural response time. What is the evidence for P300…

P50

What is the P50? The P50 event-related potential is interpreted as a physiological substrate for an inability to “gate” or inhibit irrelevant sensory information. In this paradigm, paired auditory clicks are presented, separated by a 500ms interval. The first click initiates or conditions the inhibition, while the second (test) click indexes the strength of the inhibition. P50 ratio is quantified as the amplitude of the response to the second click divided by the first. An absence of a reduced response to the second stimulus is interpreted as a failure of inhibitory mechanisms, postulated to represent a defect in sensory gating,…

NeuRA Libraries

Title Colour Legend:
Green - Topic summary is available.
Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.