Talis Bachmann | bioRxiv Science

bioRxiv2016

Disrupting dorsolateral prefrontal cortex by rTMS reduces the P300 based marker of deception

It is well known that electroencephalographic event related potential component P300 is sensitive to perception of critical items in a concealed information test. However, it is not known whether the relative level of expression of P300 as a neural marker of deception can be manipulated by means of non-invasive neuromodulation. Here, we show that while P300 exhibited systematic amplitude differences in response to the more as well as the less significant stimuli items encountered at the \"crime scene\" compared to neutral items, offline rTMS to dorsolateral prefrontal cortex attenuated P300 amplitude in response to the critical items. Yet, the individual subjects showed different sensitivity of the P300 as the marker of concealment. We conclude that rTMS can be used for subduing electrophysiological markers of deception, but this effect depends on whether the subject belongs to the group of CIT-sensitive individuals.

Neuroscience↗

bioRxiv2014

General markers of conscious visual perception and their timing

The goal of the present investigation was to identify reliable markers of conscious visual perception and to characterize their onset latency and its variability. To that end many visual stimuli from different categories were presented at near-threshold contrast and contrastive analyses were carried out on 100 balanced subsets of the data. N200 and P300 were the two reliable markers of conscious perception common to all perceived stimuli and absent for all non-perceived stimuli. The estimated mean onset latency for both markers was shortly after 200 ms. However, the onset latency of both of these markers of conscious perception showed considerable variability depending on which subsets of the data were considered. Some of this variability could be attributed to noise, but it was first and foremost the amplitude fluctuation in the condition without conscious perception that explained the variability in onset latencies of the markers of conscious perception. The present results help to understand why different studies have observed different onset times for the neural correlates of conscious perception. Moreover, the consciousness markers explored here have more generality as stimulus specificity was reduced.

Neuroscience↗