A paradox in the lateralisation of the visual evoked response

Dissociated vertical deviation: evidence of abnormal visual pathway projection.

“…VER results. Unilateral DVD: Amplitude: contrary to the results recorded in normal subjects and patients with congenital strabismus, when the temporal hemiretina was stimulated in the eye with the DVD, the amplitude recorded (mean [3][4][5][6][7][8][9][10][11][12] ,uV) at the ipsilateral occipital lobe recording electrode-i.e., the electrode ipsilateral to the half field in which the checkerboard was presented-was smaller than the amplitude recorded (mean 3-08 ,uV) at the contralateral occipital lobe recording electrode-i.e., the electrode contralateral to the half field in which the checkerboard was presented-in 78-5% of the cases (Fig. 2).…”

Microstates in Language-Related Brain Potential Maps Show Noun–Verb Differences

“…Even though the field topographies might be focalized by data transformations such as spatial high pass filtering (e.g., current source density computations), the putative sources cannot be assumed to be located perpendicular below the scalp distribution extrema (e.g., the ''paradoxical lateralization'' of the visual P100 (Barrett, Blumhardt, Halliday, Halliday, & Kriss, 1976). However, the location of the mean of the two centroid locations of a potential map is a simple estimate of the surface-projected location of an assumed single electric source that explains the field; this location of the observed noun mean fields was more to the left than that of the verb mean fields (double-ended p ϭ .020, t ϭ 2.95, df ϭ 16).…”

Electrophysiological assessment of visual pathway function in infants

“…It has been postulated that this apparently para doxical distribution for PlOO occurs because electrodes over the ipsilateral scalp are well placed to pick up activity of generators situated in the medial surface of the acti vated occipital cortex, contralateral to the stimulated field. 38 In patients with unilateral occipital lesions associated with homonymous hemianopic defects, the pattern rever sal PIOO is predominantly distributed over the side of scalp ipsilateral to the preserved half-field. The distri bution is the same when comparing responses from each eye, i.e.…”

“…t We do not favour rou tine use of sedation or anaesthesia as these procedures carry risks, and can alter the YEP (the latter can affect the ERG also), thus complicating clinical interpretation of any detected response changes. In our experience, it is diagnostically more advantageous (and cost effective) to average skin ERGs and VEPs together in order to get an estimate of both gross retinal function (from the ERG) and macular pathway function (from the YEP) in a single recording session lasting [30][31][32][33][34][35][36][37][38][39][40] A. KRISS AND 1. RUSSELL-EGGITT conditions is tested first; flash stimulation is then per formed, first under darkened conditions then photopically.…”