@misc{OguzZhouGlasaueretal., author = {Oguz, Ozgur S. and Zhou, Zhehua and Glasauer, Stefan and Wollherr, Dirk}, title = {An Inverse Optimal Control Approach to Explain Human Arm Reaching Control Based on Multiple Internal Models}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, issn = {2045-2322}, doi = {10.1038/s41598-018-23792-7}, pages = {17}, language = {en} } @misc{AnggrainiGlasauerWunderlich, author = {Anggraini, Dian and Glasauer, Stefan and Wunderlich, Klaus}, title = {Neural signatures of reinforcement learning correlate with strategy adoption during spatial navigation}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, issn = {2045-2322}, doi = {10.1038/s41598-018-28241-z}, pages = {14}, language = {en} } @misc{HausmannDaumerMacNeilageetal., author = {Hausmann, Peter and Daumer, Martin and MacNeilage, Paul R. and Glasauer, Stefan}, title = {Ecological momentary assessment of head motion: Towards normative data of head stabilization}, series = {Frontiers in Human Neuroscience}, volume = {13}, journal = {Frontiers in Human Neuroscience}, issn = {1662-5161}, doi = {10.3389/fnhum.2019.00179}, pages = {13}, abstract = {Head stabilization is fundamental for balance during locomotion but can be impaired in elderly or diseased populations. Previous studies have identified several parameters of head stability with possible diagnostic value in a laboratory setting. Recently, the ecological validity of measures obtained in such controlled contexts has been called into question. The aim of this study was to investigate the ecological validity of previously described parameters of head stabilization in a real-world setting. Ten healthy subjects participated in the study. Head and trunk movements of each subject were recorded with inertial measurement units (IMUs) for a period of at least 10 h. Periods of locomotion were extracted from the measurements and predominant frequencies, root mean squares (RMSs) and bout lengths were estimated. As parameters of head stabilization, attenuation coefficients (ACs), harmonic ratios (HRs), coherences, and phase differences were computed. Predominant frequencies were distributed tightly around 2 Hz and ACs, HRs, and coherences exhibited the highest values in this frequency range. All head stability parameters exhibited characteristics consistent with previous reports, although higher variances were observed. These results suggest that head stabilization is tuned to the 2 Hz fundamental frequency of locomotion and that previously described measures of head stability could generalize to a real-world setting. This is the first study to address the ecological validity of these measures, highlighting the potential use of head stability parameters as diagnostic tools or outcome measures for clinical trials. The low cost and ease of use of the IMU technology used in this study could additionally be of benefit for a clinical application.}, language = {en} } @misc{Glasauer, author = {Glasauer, Stefan}, title = {Sequential Bayesian updating as a model for human perception}, series = {Progress in Brain Research}, volume = {249}, journal = {Progress in Brain Research}, issn = {1875-7855}, doi = {10.1016/bs.pbr.2019.04.025}, pages = {3 -- 18}, abstract = {Sequential Bayesian updating has been proposed as model for explaining various systematic biases in human perception, such as the central tendency, range effects, and serial dependence. The present chapter introduces to the principal ideas behind Bayesian updating for the random-change model introduced previously and shows how to implement sequential updating using the exact method via probability distributions, the Kalman filter for Gaussian distributions, and a particle filter for approximate sequential updating. Finally, it is demonstrated how to couple perception to action by selecting an appropriate action based on the posterior distribution that results from sequential updating.}, language = {en} } @misc{SalmasiStemmlerGlasaueretal., author = {Salmasi, Mehrdad and Stemmler, Martin and Glasauer, Stefan and Loebel, Alex}, title = {Synaptic Information Transmission in a Two-State Model of Short-Term Facilitation}, series = {Entropy}, volume = {21}, journal = {Entropy}, number = {8}, issn = {1099-4300}, doi = {10.3390/e21080756}, pages = {13}, abstract = {Action potentials (spikes) can trigger the release of a neurotransmitter at chemical synapses between neurons. Such release is uncertain, as it occurs only with a certain probability. Moreover, synaptic release can occur independently of an action potential (asynchronous release) and depends on the history of synaptic activity. We focus here on short-term synaptic facilitation, in which a sequence of action potentials can temporarily increase the release probability of the synapse. In contrast to the phenomenon of short-term depression, quantifying the information transmission in facilitating synapses remains to be done. We find rigorous lower and upper bounds for the rate of information transmission in a model of synaptic facilitation. We treat the synapse as a two-state binary asymmetric channel, in which the arrival of an action potential shifts the synapse to a facilitated state, while in the absence of a spike, the synapse returns to its baseline state. The information bounds are functions of both the asynchronous and synchronous release parameters. If synchronous release facilitates more than asynchronous release, the mutual information rate increases. In contrast, short-term facilitation degrades information transmission when the synchronous release probability is intrinsically high. As synaptic release is energetically expensive, we exploit the information bounds to determine the energy-information trade-off in facilitating synapses. We show that unlike information rate, the energy-normalized information rate is robust with respect to variations in the strength of facilitation.}, language = {en} } @misc{GlasauerDieterichBrandt, author = {Glasauer, Stefan and Dieterich, Marianne and Brandt, Thomas}, title = {Computational neurology of gravity perception involving semicircular canal dysfunction in unilateral vestibular lesions}, series = {Progress in Brain Research}, volume = {248}, journal = {Progress in Brain Research}, issn = {1875-7855}, doi = {10.1016/bs.pbr.2019.04.010}, pages = {303 -- 317}, abstract = {Unilateral peripheral vestibular lesions not only lead to vertigo, nystagmus and imbalance, but also to a bias in the perception of verticality, which can be measured as tilt of the subjective visual vertical (SVV). Previously, this tilt has been assumed to be caused by a residual otolith bias, for example, because unequal numbers of active haircells on both sides of the utricular striola might result in an imbalance of the firing rates of central otolith neurons. Here we propose that a tilt of the subjective visual vertical might as well be caused by a vertical semicircular canal bias in the roll axis after unilateral peripheral lesions. The canal bias, acting similar to angular velocity stimuli, influences the SVV via the central gravity estimator, which under normal circumstances resolves a perceptual tilt-translation ambiguity. To illustrate our hypothesis, we compare model predictions to data on SVV measurements in patients with unilateral vestibular lesions while being tilted or being rotated eccentrically. We further embed the model of peripheral processing in a neural network that implements the idiotropic bias and represents the direction of gravity as population code in a three dimensional spherical topography.}, language = {en} } @misc{LehnenSchroederHenningsenetal., author = {Lehnen, Nadine and Schr{\"o}der, Lena and Henningsen, Peter and Glasauer, Stefan and Ramaioli, Cecilia}, title = {Deficient head motor control in functional dizziness: Experimental evidence of central sensory-motor dysfunction in persistent physical symptoms}, series = {Progress in Brain Research}, volume = {249}, journal = {Progress in Brain Research}, issn = {1875-7855}, doi = {10.1016/bs.pbr.2019.02.006}, pages = {385 -- 400}, abstract = {Understanding the mechanisms of symptoms that are insufficiently explained by organic dysfunction remains challenging. Recently, it has been proposed that such "functional symptoms" are based on erroneous sensory processing in the central nervous system (CNS), with internal expectations dominating sensory inputs. In a pilot study, we used a head motor control set-up to assess the interplay between sensory input and expectation on the example of patients with functional dizziness. Eight patients and 11 age-matched healthy controls performed large active eye-head gaze shifts towards visual targets in the natural situation and with the head moment of inertia 3.3-fold increased. The latter induces head oscillations and the expected sensory outcome of the movement, estimated in the CNS, does not match the actual sensory input. Head oscillations were assessed in patients and in healthy subjects and compared to prior results from patients with organic disease (vestibular loss and cerebellar ataxia). Head oscillations in patients with functional dizziness were different from those of healthy subjects (F(1,17) = 27.26, P < 0.001, partial η2 = 0.62), and similar to those of patients with cerebellar ataxia, and with vestibular loss (F(2,19) = 0.56, P = 0.58). Even in the natural, unweighted, condition, head oscillations were higher in functional dizziness patients than in healthy subjects (P = 0.001). Since an extensive work-up failed to demonstrate any explanatory peripheral vestibular, motor, or cerebellar organic dysfunction, these motor control deficits are a first indication of erroneous interplay between expectations and sensory input in the CNS that could account for persistent physical symptoms.}, language = {en} } @misc{GlasauerShi, author = {Glasauer, Stefan and Shi, Zhuanghua}, title = {Central Tendency as Consequence of Experimental Protocol}, series = {2019 Conference on Cognitive Computational Neuroscience, 13-16 September 2019, Berlin, Germany}, journal = {2019 Conference on Cognitive Computational Neuroscience, 13-16 September 2019, Berlin, Germany}, address = {Berlin}, doi = {10.32470/CCN.2019.1148-0}, pages = {268 -- 271}, abstract = {Perceptual biases found experimentally are often taken to indicate that we should be cautious about the veridicality of our perception in everyday life. Here we show, to the contrary, that such biases may be a consequence of the experimental protocol that cannot be generalized to other situations. We show that the central tendency, an overestimation of small magnitudes and underestimation of large ones, strongly depends on stimulus order. If the same set of stimuli is, rather than being presented in the usual randomized order, is applied in an order that displays only small changes from one trial to the next, the central tendency decreases significantly. This decrease is predicted by a probabilistic model that assumes iterative trial-wise updating of a prior of the stimulus distribution. We conclude that the commonly used randomization of stimuli introduces systematic perceptual biases that may not relevant in everyday life.}, language = {en} } @misc{DietrichHeidgerSchnieppetal., author = {Dietrich, Haike and Heidger, F. and Schniepp, Roman and MacNeilage, Paul R. and Glasauer, Stefan and W{\"u}hr, Max}, title = {Head motion predictability explains activity-dependent suppression of vestibular balance control}, series = {Scientific Reports}, volume = {10}, journal = {Scientific Reports}, issn = {2045-2322}, doi = {10.1038/s41598-019-57400-z}, abstract = {Vestibular balance control is dynamically weighted during locomotion. this might result from a selective suppression of vestibular inputs in favor of a feed-forward balance regulation based on locomotor efference copies. The feasibility of such a feed-forward mechanism should however critically depend on the predictability of head movements (HMP) during locomotion. To test this, we studied in 10 healthy subjects the differential impact of a stochastic vestibular stimulation (SVS) on body sway (center-of-pressure, COP) during standing and walking at different speeds and compared it to activity-dependent changes in HMp. SVS-cop coupling was determined by correlation analysis in frequency and time domains. HMP was quantified as the proportion of head motion variance that can be explained by the average head trajectory across the locomotor cycle. SVS-COP coupling decreased from standing to walking and further dropped with faster locomotion. Correspondingly, HMP increased with faster locomotion. Furthermore, SVS-COP coupling depended on the gait-cycle-phase with peaks corresponding to periods of least HMP. These findings support the assumption that during stereotyped human self-motion, locomotor efference copies selectively replace vestibular cues, similar to what was previously observed in animal models.}, language = {en} } @misc{SalmasiGlasauerStemmler, author = {Salmasi, Mehrdad and Glasauer, Stefan and Stemmler, Martin}, title = {Short-term facilitation and neurotransmitter spillover counteract each other in neuronal information transmission}, series = {28th Annual Computational Neuroscience Meeting: CNS*2019}, journal = {28th Annual Computational Neuroscience Meeting: CNS*2019}, issn = {1471-2202}, doi = {10.1186/s12868-019-0538-0}, pages = {155 -- 156}, language = {en} }