Contrast independence of dynamic random dot correlogram evoked VEP amplitude.

Dynamic random dot correlograms (DRDCs) are binocular stimuli that evoke a percept and a visual evoked potential (VEP) only in case of a mature and functional binocular system. DRDC-VEP is a method extensively used to study cortical binocularity in human infants and nonverbal children. Although the DRDC-VEP was invented 3 decades ago, neither the fundamental parameters, including contrast, of the stimulation nor the cerebral processing mechanisms have been clarified.

Excitability changes induced in the human primary visual cortex by transcranial direct current stimulation: direct electrophysiological evidence.

Purpose: Transcranial direct current stimulation (tDCS) has been shown to modify the perception threshold of phosphenes elicited by transcranial magnetic stimulation (TMS). The current study was undertaken to examine whether tDCS, when applied over the occipital cortex, is also able to affect visual-evoked potentials (VEPs), which characterize occipital activation in response to visual stimulation, in a polarity-specific way.

Method: For this purpose, VEPs evoked by sinusoidal luminance grating in an on/off mode were recorded before, immediately after, and 10, 20, and 30 minutes after the end of 5, 10, or 15 minutes of anodal or cathodal tDCS of the primary visual cortex.

Facilitation of probabilistic classification learning by transcranial direct current stimulation of the prefrontal cortex in the human.

The aim of our study was to test if the electrical stimulation of the prefrontal cortex (PFC) could modify probabilistic classification learning (PCL). Transcranial direct current stimulation (tDCS) was administered to the left prefrontal and to the primary visual cortex of 22 healthy subjects while they performed a PCL task. In this task subjects learned which of two outcomes would occur on each trial after presentation of a particular combination of cues.

Pulse configuration-dependent effects of repetitive transcranial magnetic stimulation on visual perception.

Transcranial magnetic stimulation (TMS) is a noninvasive technique for direct stimulation of the neocortex. In the last two decades it is successfully applied in the study of motor and sensory physiology. TMS uses the indirect induction of electrical fields in the brain generated by intense changes of magnetic fields applied to the scalp.