The Max Planck Institute for Biological Cybernetics is located in Tübingen, Baden-Württemberg, Germany. It is one of 80 institutes in the Max Planck Society .The institute is studying signal and information processing in the brain. We know that our brain is constantly processing a vast amount of sensory and intrinsic information by which our behavior is coordinated accordingly. How the brain actually achieves these tasks is less well understood, for example, how it perceives, recognizes, and learns new objects. The scientists at the Max Planck Institute for Biological Cybernetics aim to determine which signals and processes are responsible for creating a coherent percept of our environment and for eliciting the appropriate behavior. Scientists of three departments and seven research groups are working towards answering fundamental questions about processing in the brain, using different approaches and methods. Wikipedia.
Mooij J.M.,Max Planck Institute for Biological Cybernetics
Journal of Machine Learning Research | Year: 2010
This paper describes the software package libDAI, a free & open source C++ library that provides implementations of various exact and approximate inference methods for graphical models with discrete-valued variables. libDAI supports directed graphical models (Bayesian networks) as well as undirected ones (Markov random fields and factor graphs). It offers various approximations of the partition sum, marginal probability distributions and maximum probability states. Parameter learning is also supported. A feature comparison with other open source software packages for approximate inference is given. libDAI is licensed under the GPL v2+ license and is available at http://www.libdai.org. © 2010.
Dopjans L.,Max Planck Institute for Biological Cybernetics
Journal of vision | Year: 2012
Even though we can recognize faces by touch surprisingly well, haptic face recognition performance is still worse than for visual exploration. One possibility for this performance difference might be due to different encoding strategies in the two modalities, namely, holistic encoding in vision versus serial encoding in haptics. Here, we tested this hypothesis by promoting serial encoding in vision, using a novel, gaze-restricted display that limited the effective field of view in vision to resemble that of haptic exploration. First, we compared haptic with gaze-restricted and unrestricted visual face recognition. Second, we used the face inversion paradigm to assess how encoding differences might affect processing strategies (featural vs. holistic). By promoting serial encoding in vision, we found equal face recognition performance in vision and haptics with a clear switch from holistic to featural processing, suggesting that performance differences in visual and haptic face recognition are due to modality-specific encoding strategies.
Pohmann R.,Max Planck Institute for Biological Cybernetics
Magnetic Resonance in Medicine | Year: 2010
Quantification of perfusion in white matter is still difficult due to its low level, causing an often insufficiently low signal-to-noise ratio, and its long and inhomogeneous transit delays. Here, a technique is presented that accurately measures white matter perfusion by combining a spectroscopic single-voxel localization technique (point-resolved spectroscopy) with a pulsed arterial spin labeling encoding scheme (flow-sensitive alternating inversion recovery) to specifically address the properties of white matter. The transit delay was measured by shifting the position of a slice-selective saturation pulse between inversion and acquisition. Perfusion measurements resulted in values of 15.6 ± 3.2 mL/100 g/min in the left and 15.2 ± 4.8 mL/100 g/min in the right hemispheric white matter and 83.2 ± 15.2 mL/100 g/min in cortical gray matter. Taking dispersion of the transit times into account does not cause a significant change in the measured values. © 2010 Wiley-Liss, Inc.
Lewis R.,Max Planck Institute for Biological Cybernetics |
Noppeney U.,Max Planck Institute for Biological Cybernetics
Journal of Neuroscience | Year: 2010
Audiovisual synchrony enables integration of dynamic visual and auditory signals into a more robust and reliable multisensory percept. In this fMRI study, we investigated the neural mechanisms by which audiovisual synchrony facilitates shape and motion discrimination under degraded visual conditions. Subjects were presented with visual patterns that were rotated by discrete increments at irregular and unpredictable intervals while partially obscured by a dynamic noise mask. On synchronous trials, each rotation coincided with an auditory click. On asynchronous trials, clicks were noncoincident with the rotational movements (but with identical temporal statistics). Subjects discriminated shape or rotational motion profile of the partially hidden visual stimuli. Regardless of task context, synchronous signals increased activations bilaterally in (1) calcarine sulcus (CaS) extending into ventral occipitotemporal cortex and (2) Heschl's gyrus extending into planum temporale (HG/PT) compared with asynchronous signals. Adjacent to these automatic synchrony effects, synchrony-induced activations in lateral occipital (LO) regions were amplified bilaterally during shape discrimination and in the right posterior superior temporal sulcus (pSTS) during motion discrimination. Subjects' synchrony-induced benefits in motion discrimination significantly predicted blood oxygenation level-dependent synchrony effects in V5/hMT+. According to dynamic causal modeling, audiovisual synchrony increased connectivity between CaS and HG/PT bidirectionally, whereas shape and motion tasks increased forwards connectivity from CaS to LO or to pSTS, respectively. To increase the salience of partially obscured moving objects, audiovisual synchrony may amplify visual activations by increasing the connectivity between low level visual and auditory areas. These automatic synchrony-induced response amplifications may then be gated to higher order areas according to behavioral relevance and task context. Copyright © 2010 the authors.
Angelovski G.,Max Planck Institute for Biological Cybernetics
Angewandte Chemie - International Edition | Year: 2016
Bioresponsive MRI contrast agents hold great promise for monitoring major physiological and pathological processes in a non-invasive manner. They are capable of altering the acquired MRI signal as a consequence of changes in their microenvironment, thus allowing real-time functional reporting in living organisms. Importantly, chemistry offers diverse solutions for the design of agents which respond to a great number of specific targets. However, the path to the successful utilization of these biomarkers in the desired functional MRI studies involves careful consideration of multiple scientific, technical, and practical issues across various research disciplines. This Minireview highlights the critical steps for planning and executing such multidisciplinary projects with an aim to substantially improve our knowledge of essential biological processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Hong S.T.,Max Planck Institute for Biological Cybernetics
Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine | Year: 2011
Single voxel magnetic resonance spectroscopy with ultrashort echo time was implemented at 16.4 T to enhance the neurochemical profile of the rat brain in vivo. A TE of 1.7 msec was achieved by sequence optimization and by using short-duration asymmetric pulses. Macromolecular signal components were parameterized individually and included in the quantitative analysis, replacing the use of a metabolite-nulled spectrum. Because of the high spectral dispersion, several signals close to the water line could be detected, and adjacent peaks could be resolved. All 20 metabolites detected in this study were quantified with Cramér-Rao lower bounds below 20%, implying reliable quantification accuracy. The signal of acetate was detected for the first time in rat brain in vivo with Cramér-Rao lower bounds of 16% and a concentration of 0.52 μmol/g. The absolute concentrations of most metabolites showed close agreement with values previously measured using in vivo (1)H NMR spectroscopy and in vitro biochemical assay. © 2010 Wiley-Liss, Inc.
Panagiotaropoulos T.I.,Max Planck Institute for Biological Cybernetics
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2014
The combination of electrophysiological recordings with ambiguous visual stimulation made possible the detection of neurons that represent the content of subjective visual perception and perceptual suppression in multiple cortical and subcortical brain regions. These neuronal populations, commonly referred to as the neural correlates of consciousness, are more likely to be found in the temporal and prefrontal cortices as well as the pulvinar, indicating that the content of perceptual awareness is represented with higher fidelity in higher-order association areas of the cortical and thalamic hierarchy, reflecting the outcome of competitive interactions between conflicting sensory information resolved in earlier stages. However, despite the significant insights into conscious perception gained through monitoring the activities of single neurons and small, local populations, the immense functional complexity of the brain arising from correlations in the activity of its constituent parts suggests that local, microscopic activity could only partially reveal the mechanisms involved in perceptual awareness. Rather, the dynamics of functional connectivity patterns on a mesoscopic and macroscopic level could be critical for conscious perception. Understanding these emergent spatio-temporal patterns could be informative not only for the stability of subjective perception but also for spontaneous perceptual transitions suggested to depend either on the dynamics of antagonistic ensembles or on global intrinsic activity fluctuations that may act upon explicit neural representations of sensory stimuli and induce perceptual reorganization. Here, we review the most recent results from local activity recordings and discuss the potential role of effective, correlated interactions during perceptual awareness.
Harmeling S.,Max Planck Institute for Biological Cybernetics |
Williams C.K.I.,University of Edinburgh
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2011
Inferring latent structures from observations helps to model and possibly also understand underlying data generating processes. A rich class of latent structures is the latent trees, i.e., tree-structured distributions involving latent variables where the visible variables are leaves. These are also called hierarchical latent class (HLC) models. Zhang and Kočka [CHECK END OF SENTENCE] proposed a search algorithm for learning such models in the spirit of Bayesian network structure learning. While such an approach can find good solutions, it can be computationally expensive. As an alternative, we investigate two greedy procedures: The BIN-G algorithm determines both the structure of the tree and the cardinality of the latent variables in a bottom-up fashion. The BIN-A algorithm first determines the tree structure using agglomerative hierarchical clustering, and then determines the cardinality of the latent variables as for BIN-G. We show that even with restricting ourselves to binary trees, we obtain HLC models of comparable quality to Zhang's solutions (in terms of cross-validated log-likelihood), while being generally faster to compute. This claim is validated by a comprehensive comparison on several data sets. Furthermore, we demonstrate that our methods are able to estimate interpretable latent structures on real-world data with a large number of variables. By applying our method to a restricted version of the 20 newsgroups data, these models turn out to be related to topic models, and on data from the PASCAL Visual Object Classes (VOC) 2007 challenge, we show how such tree-structured models help us understand how objects co-occur in images. For reproducibility of all experiments in this paper, all code and data sets (or links to data) are available at http://people.kyb.tuebingen.mpg.de/harmeling/ code/ltt-1.4.tar. © 2006 IEEE.
Massimiliano D.L.,Max Planck Institute for Biological Cybernetics
Vision Research | Year: 2011
Handling a compliant object using a pinch grasp provides sensory information about deformation and resistive force from both index finger and thumb. In this paper, an object with rigid surfaces and composed of two compliant materials fixed on a central position is used to address how information from the two fingers is integrated into a holistic percept of compliance. Results indicate that with small differences in material compliance there is a small tendency to rely more on the information at the index finger. With larger differences in material compliance participants adopt different movement patterns with the two fingers to explore the objects. Compliance judgments depend on the relative amount of motion and force exerted-the finger that presses more contributes more to the final estimate. This tendency is consistent with the utilization of a unique force signal for the two fingers. The uneven contribution of the sensory information in the pinch leads to predictable compliance discrimination performance from the performance obtained using the fingers independently. © 2011 Elsevier Ltd.
Yu X.,Max Planck Institute for Biological Cybernetics
Nature Methods | Year: 2016
Magnetic resonance imaging (MRI) sensitivity approaches vessel specificity. We developed a single-vessel functional MRI (fMRI) method to image the contribution of vascular components to blood oxygenation level–dependent (BOLD) and cerebral blood volume (CBV) fMRI signal. We mapped individual vessels penetrating the rat somatosensory cortex with 100-ms temporal resolution by MRI with sensory or optogenetic stimulation. The BOLD signal originated primarily from venules, and the CBV signal from arterioles. The single-vessel fMRI method and its combination with optogenetics provide a platform for mapping the hemodynamic signal through the neurovascular network with specificity at the level of individual arterioles and venules. © 2016 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.