Effects of vagal nerve stimulation on time perception

In this study, it was aimed to investigate the effects of Vagal Nerve Stimulation (VNS) turning off on time perception in patients with drug-resistant epilepsy. After completing the Beck Depression Inventory and Beck Anxiety Scale, the computerized time perception tests; Paced Motor Timing Test, Time Interval Comparison Test, Time Interval Reproduction Test (TIRT) and Time Interval Estimation Test were applied to 14 patients included in the study, and the data were analyzed. Time Interval Reproduction Test are evaluated; significant changes were observed in TIRT in both the reported time value (p = 0.03; Z = -2.166) and the ratio value (p = 0.03; Z = -2.166) for 2000 millisecond (ms). These values are higher when VNS is turned off. No significant change was observed in other findings. In our study, it was revealed that for all time units in the TIRT, the internal clock runs faster when the VNS is on. Pace of time is perceived slower than it actually is. The increase in attention results with a slowing down in time perception. For example, at the time of a traffic accident, attention is at the highest level and the accident is perceived as is in slow motion. When it is evaluated according to Scalar Expectancy Theory (SET), positive effects on alertness, attention and focus that occur with VNS causes the internal clock to accelerate and slows down the time perception. In our study, in the 2000 ms Time Interval Reproduction Test with VNS on; the internal clock runs faster and time is perceived as running slower. This slowdown in time perception can be interpreted as an indirect indicator of increased attention with VNS. Although considering the effects of VNS on noradrenaline, serotonin, dopamine and depression the internal clock is expected to slow down when VNS is on. Our results reveal that time perception has a complicated mechanism than known.