Methods: Body sway was analyzed by measuring the center of pressure (CoP) in 10 healthy participants on a pressure-sensitive treadmill during standing and walking at 0.4 or 0.8 m/s. Continuous SVS (0–25 Hz; peak amplitude at±4.5 mA) was delivered by a bipolar binaural electrode configuration over the mastoid processes to evoke postural responses in the roll plane. Time-dependent coherence between SVS and medio-lateral body sway was analyzed to examine the dynamic impact of vestibular cues during locomotion. HMP was estimated using a previously established model (MacNeilage and Glasauer, 2017).
Results: SVS-CoP coherence decreased from standing to slow walking and further decreased with increasing locomotor speed (p< 0.001). Correspondingly, HMP increased with faster locomotion (p= 0.001). SVS-CoP coherence depended on the gait cycle phase with two distinct peaks occurring at 25 …
Surface filling-in and contour interpolation contribute independently to Kanizsa figure formation
(2018)
Both, the hippocampal formation and the neocortex are contributing to declarative memory, but their functional specialization remains unclear. We investigated the differential contribution of both memory systems during free recall of word lists. In total, 21 women and 17 men studied the same list but with the help of different encoding associations. Participants associated the words either sequentially with the previous word on the list, with spatial locations on a well-known path, or with unique autobiographical events. After intensive rehearsal, subjects recalled the words during functional magnetic resonance imaging (fMRI). Common activity to all three types of encoding associations was identified in the posterior parietal cortex, in particular in the precuneus. Additionally, when associating spatial or autobiographical material, retrosplenial cortex activity was elicited during word list recall, while hippocampal activity emerged only for autobiographically associated words. These findings support a general, critical function of the precuneus in episodic memory storage and retrieval. The encoding-retrieval repetitions during learning seem to have accelerated hippocampus-independence and lead to direct neocortical integration in the sequentially associated and spatially associated word list tasks. During recall of words associated with autobiographical memories, the hippocampus might add spatiotemporal information supporting detailed scenic and contextual memories.
The vestibular sensors in the inner ear measure head movement with respect to an inertial frame of reference. The chapter describes the principles of measurement of the vestibular sensors, the physical stimuli that are measured, and specific issues that require central processing. An overview about so-called artificial vestibular stimuli that mimic the effect of natural head movement is provided.