Page 138 - Migraine, the heart and the brain

Chapter 7
ve minus phase two). Secondary outcome was the individual spread of x coordinates observed when there was no visual feedback of the hand (movement variability; phase two).
During classical Pavlovian eyeblink conditioning an eyeblink eliciting unconditioned stimulus (US; e.g. an air puff) is repeatedly preceded by a conditioned stimulus (CS; e.g. an auditory tone), ultimately inducing a conditioned response (CR) on the CS alone (Koekkoek et al., 2003; Koekkoek et al., 2005) (Fig. 3A). Participants are equipped with a headphone, video goggles (Logitech, USA) and an air puff nozzle connected to it. The 580 ms tone CS (1 kHz, 70-90 dB) is delivered via the headphone, while the 30 ms air puff US is applied to the left cornea via the nozzle, creating a CS-US interval of 550 ms. The experiment consists of 8 blocks, each consisting of 1 US-only, 6 paired CS-US, and 1 CS-only trial (Fig. 3A). Eyelid movements are recorded with the Magnetic Distance Measurement Technique (MDMT) (Koekkoek et al., 2005; Smit et al., 2008). Individual eyeblink traces are analyzed offline with custom computer software (LabVIEW®) by an experienced researcher, blinded for participant characteristics. Eyelid movements larger than 2 x SD of the 500 ms pre-CS period are considered as signi cant and further categorized into auditory startle response (latency to peak 10- 150 ms) and cerebellar CRs (latency to onset 150-500 ms and latency to peak 150-600 ms) (Fig. 3B). As primary outcome measures for this test of learning-dependent timing we used the adaptive timing of eyeblink CRs as represented by the mean latency to CR onset and mean latency to CR peak-time (Table 5). As secondary outcome measures we used the peak-amplitude of the CRs per session, expressed as percentage of the mean URs in US-only trials, and the percentage of CRs of paired trials before and after conditioning, applying a 2 SD criterion for eyelid position to pass baseline and an attention check for the nal blocks (using a 5 SD criterion did not result in additional signi cant differences among groups; data not shown). CR peak-amplitude and CR peak-time were only calculated for trials in which a CR was present and auditory startle responses were not further analyzed.
The body-sway task measures balance abnormalities during stance and gait tasks by quantifying body-sway using body-worn gyroscopes measuring angular velocity (Allum and Carpenter, 2005; Horlings et al., 2008; Kung et al., 2009). The equipment consists of 1) a foam support (density of 25 kg/m3) with a height, width and length of 10 cm, 44 cm and 102 cm, respectively, on which the subjects have to stand and walk; 2) two digital angular velocity transducers with low drift (less than 6o/h) that are attached to the lower back at L1-L3 level using a special belt (Supplementary gure 1E) (Swaystar system, Balance International Innovations GmbH Switzerland); and 3)
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