Improving the Reliability of the Flash Visual Evoked Potential P2 (FVEP-P2).

Influence of colors in distractor videos on the recording of cortical auditory evoked potentials

ABSTRACT Purpose To compare the morphological differences in CAEP obtained with black-and-white versus colored distractor videos, and to verify whether the black-and-white format reduces response variability. Methods This cross-sectional analytical study, approved by an ethics committee (protocol nº 3.477.022), included 30 adults aged 18–35 years with normal hearing. Participants underwent CAEP recordings using /ba/ and /da/ stimuli under two conditions: silent black-and-white and silent colored videos. Latencies, amplitudes, and interlatency intervals were analyzed using paired t-tests and Levene’s test (p < 0.05). Results Colored videos resulted in longer latencies for P1 and P2 in both ears, reduced P1 amplitude in the right ear, and increased P2 amplitude bilaterally. The P1-N1 interval was greater with black-and-white videos, while the N1-P2 interval increased with colored videos in the left ear. Conclusion The use of colored videos influences CAEP morphology and variability and should be carefully considered in clinical and research contexts.

The steady-state visual evoked potential (SSVEP): A review of applications in cognitive and clinical neuroscience and neural engineering

A scoping, narrative roadmap of SSVEP applications organized into three primary domains is provided, highlighting the versatility of SSVEPs in investigating neural mechanisms, supporting diagnosis and treatment of neurological and psychiatric conditions, and advancing brain-computer interface technology.

Evaluating the reliability of structured light entoptic tasks.

Human perception of polarised light, known as Haidinger's brushes, is linked to macular health but is typically too faint for reliable clinical use. Structured light can enhance these entoptic patterns, but the test-retest reliability of this approach requires validation. Here, we evaluated the reliability of a structured light-based psychophysical task in twenty-five participants (fifty eyes) across two sessions separated by one to fourteen days. Participants viewed structured light stimuli that produced rotating entoptic patterns and identified the rotation direction in a two-alternative forced-choice paradigm while a central obstruction varied in size to determine retinal eccentricity thresholds. Intraclass correlation coefficients demonstrated good to excellent reliability, with values of 0.83 for right eyes and 0.93 for left eyes. Bland-Altman analysis revealed non-significant mean differences of -0.32 degrees and - 0.12 degrees for right and left eyes, respectively, with limits of agreement spanning approximately 6° and 4° around mean thresholds of ~ 6.1° and ~ 6.5°, confirming an absence of systematic bias. These findings indicate that structured light-based psychophysical tasks can yield repeatable measurements of entoptic pattern extent in healthy individuals. Further validation in clinical populations and older age groups is required before the method can be recommended for clinical screening.

Electrophysiological signatures of visual cortical dysfunction in Parkinson's disease: An integrative EEG-based review.

Parkinson's disease (PD) can disrupt retinal, early cortical, oscillatory, and distributed visuoperceptual processing. This structured integrative review synthesized human evidence from pattern electroretinography (PERG), electroretinography (ERG), optical coherence tomography (OCT)-linked and conventional visual evoked potentials (VEPs), visual event-related potentials (ERPs), electroencephalography (EEG), steady-state visual evoked potentials (ssVEPs), and occipital transcranial magnetic stimulation-electroencephalography (TMS-EEG), with searches verified up to 18 July 2026. Findings were organized into four domains: 1) Retinal and retinocortical contributions: retinal dysfunction can delay or attenuate afferent input, yet concurrent retinal physiology is rarely measured; therefore VEP abnormalities cannot generally be assigned specifically to cortex. 2) Early visual encoding: prolonged pattern-reversal P100 latency is the most reproducible finding, including a pooled 6.04-ms delay across 20 case-control studies, whereas amplitude findings are inconsistent. 3) Oscillatory dynamics: PD-specific ssVEP evidence suggests altered contextual gain, but it derives from one small unreplicated study; gamma-band and task-EEG findings remain sparse and confound-sensitive. 4) Higher-order and network-level processing: visual ERPs, resting microstates, and occipital TMS-EEG indicate possible associations with hallucinations, cognition, and network connectivity, but current studies are cross-sectional or unreplicated. Overall, PD is characterized by multilevel visual-pathway dysfunction rather than a single cortex-specific biomarker. Ophthalmic status, retinal physiology, medication state, cognition, mood, sleep, and recording quality should be controlled before electrophysiological measures are used for localization, stratification, or prognosis.

Neurophysiological Evidence of Visual Cortical Alterations in Mild Primary Glaucoma: A Resting-State EEG Microstate Study

Early Ocular Response to Visual Motion in Patients With Persistent Postural‐Perceptual Dizziness

Persistent postural‐perceptual dizziness (PPPD) patients with visual dependency rely more on visual cues and may have altered oculomotor responses to visual motion. This study examined early eye movement responses to large‐field motion stimuli—the ocular following responses (OFRs)—in 30 PPPD patients and 29 healthy controls. Participants viewed horizontal motion in peripheral and/or central visual fields while eye movements were recorded. OFR velocity 200 ms after stimulus onset and suppression efficacy were analyzed across four central field sizes from 5° to 42° radius. Both groups exhibited strong OFRs to stimuli in the central visual field that increased with the size of the stimulation area. When the central visual field was stationary and the surrounding area moved, patients showed significantly higher eye velocity than controls. Both groups could partially suppress OFRs, but healthy controls were more effective at suppressing eye movements during peripheral stimulation. Patients also showed greater visual dependency on the dynamic subjective visual vertical (2.2° vs. 1.2°), which correlated with OFR magnitude. Overall, PPPD patients were less able to keep their eyes still during peripheral visual motion, producing greater retinal slip and disrupting volitional fixation—an abnormality that may contribute to dizziness and discomfort in visually complex environments.