Gail, Alexander

[["dc.bibliographiccitation.firstpage","519"],["dc.bibliographiccitation.issue","3-5"],["dc.bibliographiccitation.journal","Visual Cognition"],["dc.bibliographiccitation.lastpage","530"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Eckhorn, Reinhard"],["dc.contributor.author","Bruns, Andreas"],["dc.contributor.author","Saam, Mirko"],["dc.contributor.author","Gail, Alexander"],["dc.contributor.author","Gabriel, Andreas"],["dc.contributor.author","Brinksmeyer, Hans Jörg"],["dc.date.accessioned","2017-09-07T11:47:50Z"],["dc.date.available","2017-09-07T11:47:50Z"],["dc.date.issued","2002"],["dc.description.abstract","We summarize recent studies of our group from the primary visual cortex V1 of behaving monkeys referring to the hypothesis of spatial feature binding by γ-synchronization (30-90 Hz). In agreement with this hypothesis the data demonstrates decoupling of γ-activities among neural groups representing figure and ground. As γ-synchronization in V1 is restricted to cortical ranges of few millimeters, feature binding may equivalently be restricted in visual space. Closer inspection shows that the restriction in synchrony is due to far-reaching travelling γ-waves with changing phase coupling. Based on this observation we extend the initial binding-by-synchronization hypothesis and suggest object continuity to be coded by phase continuity. It is further argued that the spatial phase changes of the V1 γ-waves in general will also limit lateral phase coupling to higher levels of processing. Instead of phase-locked γ-coupling, corticocortical cooperation among γ-processes may be mediated by mutual amplitude modulations that are more reliable than phase synchrony over larger distances. The relevance of this concept of corticocortical binding is demonstrated with subdural recordings from human subjects performing cognitive tasks. The experimental results are discussed on the basis of network models with spiking neurons."],["dc.identifier.doi","10.1080/13506280143000098"],["dc.identifier.gro","3150728"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7516"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","1350-6285"],["dc.title","Flexible cortical gamma-band correlations suggest neural principles of visual processing"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","287"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Experimental Brain Research"],["dc.bibliographiccitation.lastpage","296"],["dc.bibliographiccitation.volume","208"],["dc.contributor.author","Westendorff, Stephanie"],["dc.contributor.author","Gail, Alexander"],["dc.date.accessioned","2017-09-07T11:47:48Z"],["dc.date.available","2017-09-07T11:47:48Z"],["dc.date.issued","2010"],["dc.description.abstract","Reach movement planning involves the representation of spatial target information in different reference frames. Neurons at parietal and premotor stages of the cortical sensorimotor system represent target information in eye- or hand-centered reference frames, respectively. How the different neuronal representations affect behavioral parameters of motor planning and control, i.e. which stage of neural representation is relevant for which aspect of behavior, is not obvious from the physiology. Here, we test with a behavioral experiment if different kinematic movement parameters are affected to a different degree by either an eye- or hand-reference frame. We used a generalized anti-reach task to test the influence of stimulus-response compatibility (SRC) in eye- and hand-reference frames on reach reaction times, movement times, and endpoint variability. While in a standard anti-reach task, the SRC is identical in the eye- and hand-reference frames, we could separate SRC for the two reference frames. We found that reaction times were influenced by the SRC in eye- and hand-reference frame. In contrast, movement times were only influenced by the SRC in hand-reference frame, and endpoint variability was only influenced by the SRC in eye-reference frame. Since movement time and endpoint variability are the result of planning and control processes, while reaction times are consequences of only the planning process, we suggest that SRC effects on reaction times are highly suited to investigate reference frames of movement planning, and that eye- and hand-reference frames have distinct effects on different phases of motor action and different kinematic movement parameters."],["dc.identifier.doi","10.1007/s00221-010-2481-2"],["dc.identifier.gro","3150734"],["dc.identifier.pmid","21076817"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7523"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","0014-4819"],["dc.title","What is ‘anti’ about anti-reaches? Reference frames selectively affect reaction times and endpoint variability"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","840"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Cerebral Cortex"],["dc.bibliographiccitation.lastpage","850"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Gail, Alexander"],["dc.contributor.author","Brinksmeyer, Hans Jörg"],["dc.contributor.author","Eckhorn, Reinhard"],["dc.date.accessioned","2017-09-07T11:47:47Z"],["dc.date.available","2017-09-07T11:47:47Z"],["dc.date.issued","2002"],["dc.description.abstract","Previous work on figure–ground coding in monkey V1 revealed enhanced spike rates within an object's surface representation, synchronization of gamma oscillations (γ = 35–90 Hz) in object and background regions, but no decrease in signal correlation across the representation of a contour. The latter observation seems to contradict previous statements on the role of γ-synchronization for scene segmentation. We re-examine these findings by analyzing different coupling measures and frequency ranges of population activities potentially contributing to figure–ground segregation. Multiple unit activity (MUA) and local field potentials (LFPs) were recorded by parallel μ-electrodes in monkey V1 during stimulation by a grating in which an object was defined by a shifted rectangle. In contradiction to the conclusions in previous work, we find strong decoupling of population activity between figure and ground representations compared to the situation in which the object is absent. In particular, coherence of lateγ-LFPs is strongly reduced, while reduction is absent during the early epochs of high-amplitude transients for LFP- and MUA-coherence at all frequencies, and at low frequencies also in the subsequent epochs. Our results of decoupling in late LFP γ-components among figure and ground representations suggest that these signals may support figure–ground segregation."],["dc.identifier.doi","10.1093/cercor/10.9.840"],["dc.identifier.gro","3150717"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7504"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","1460-2199"],["dc.title","Contour Decouples Gamma Activity Across Texture Representation in Monkey Striate Cortex"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2360"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Journal of Neurophysiology"],["dc.bibliographiccitation.lastpage","2375"],["dc.bibliographiccitation.volume","113"],["dc.contributor.author","Westendorff, Stephanie"],["dc.contributor.author","Kuang, Shenbing"],["dc.contributor.author","Taghizadeh, Bahareh"],["dc.contributor.author","Donchin, Opher"],["dc.contributor.author","Gail, Alexander"],["dc.date.accessioned","2017-09-07T11:47:49Z"],["dc.date.available","2017-09-07T11:47:49Z"],["dc.date.issued","2015"],["dc.description.abstract","Different error signals can induce sensorimotor adaptation during visually guided reaching, possibly evoking different neural adaptation mechanisms. Here we investigate reach adaptation induced by visual target errors without perturbing the actual or sensed hand position. We analyzed the spatial generalization of adaptation to target error to compare it with other known generalization patterns and simulated our results with a neural network model trained to minimize target error independent of prediction errors. Subjects reached to different peripheral visual targets and had to adapt to a sudden fixed-amplitude displacement (“jump”) consistently occurring for only one of the reach targets. Subjects simultaneously had to perform contralateral unperturbed saccades, which rendered the reach target jump unnoticeable. As a result, subjects adapted by gradually decreasing reach errors and showed negative aftereffects for the perturbed reach target. Reach errors generalized to unperturbed targets according to a translational rather than rotational generalization pattern, but locally, not globally. More importantly, reach errors generalized asymmetrically with a skewed generalization function in the direction of the target jump. Our neural network model reproduced the skewed generalization after adaptation to target jump without having been explicitly trained to produce a specific generalization pattern. Our combined psychophysical and simulation results suggest that target jump adaptation in reaching can be explained by gradual updating of spatial motor goal representations in sensorimotor association networks, independent of learning induced by a prediction-error about the hand position. The simulations make testable predictions about the underlying changes in the tuning of sensorimotor neurons during target jump adaptation."],["dc.identifier.doi","10.1152/jn.00483.2014"],["dc.identifier.gro","3150727"],["dc.identifier.pmid","25609106"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7515"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.issn","0022-3077"],["dc.title","Asymmetric generalization in adaptation to target displacement errors in humans and in a neural network model"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","9490"],["dc.bibliographiccitation.issue","30"],["dc.bibliographiccitation.journal","The Journal of neuroscience"],["dc.bibliographiccitation.lastpage","9499"],["dc.bibliographiccitation.volume","29"],["dc.contributor.author","Gail, Alexander"],["dc.contributor.author","Klaes, Christian"],["dc.contributor.author","Westendorff, Stephanie"],["dc.date.accessioned","2017-09-07T11:47:44Z"],["dc.date.available","2017-09-07T11:47:44Z"],["dc.date.issued","2009"],["dc.description.abstract","Planning goal-directed movements requires the combination of visuospatial with abstract contextual information. Our sensory environment constrains possible movements to a certain extent. However, contextual information guides proper choice of action in a given situation and allows flexible mapping of sensory instruction cues onto different motor actions. We used anti-reach tasks to test the hypothesis that spatial motor-goal representations in cortical sensorimotor areas are gain modulated by the behavioral context to achieve flexible remapping of spatial cue information onto arbitrary motor goals. We found that gain modulation of neuronal reach goal representations is commonly induced by the behavioral context in individual neurons of both, the parietal reach region (PRR) and the dorsal premotor cortex (PMd). In addition, PRR showed stronger directional selectivity during the planning of a reach toward a directly cued goal (pro-reach) compared with an inferred target (anti-reach). PMd, however, showed stronger overall activity during reaches toward inferred targets compared with directly cued targets. Based on our experimental evidence, we suggest that gain modulation is the computational mechanism underlying the integration of spatial and contextual information for flexible, rule-driven stimulus–response mapping, and thereby forms an important basis of goal-directed behavior. Complementary contextual effects in PRR versus PMd are consistent with the idea that posterior parietal cortex preferentially represents sensory-driven, “automatic” motor goals, whereas frontal sensorimotor areas are stronger engaged in the representation of rule-based, “inferred” motor goals."],["dc.identifier.doi","10.1523/jneurosci.1095-09.2009"],["dc.identifier.gro","3150713"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7500"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","0270-6474"],["dc.title","Implementation of Spatial Transformation Rules for Goal-Directed Reaching via Gain Modulation in Monkey Parietal and Premotor Cortex"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1039"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","IEEE Transactions on Neural Networks"],["dc.bibliographiccitation.lastpage","1052"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Eckhorn, Reinhard"],["dc.contributor.author","Gail, Alexander"],["dc.contributor.author","Bruns, Andreas"],["dc.contributor.author","Gabriel, A."],["dc.contributor.author","Al-Shaikhli, Basim"],["dc.contributor.author","Saam, Mirko"],["dc.date.accessioned","2017-09-07T11:47:46Z"],["dc.date.available","2017-09-07T11:47:46Z"],["dc.date.issued","2004"],["dc.identifier.doi","10.1109/tnn.2004.833130"],["dc.identifier.gro","3150722"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7510"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","1045-9227"],["dc.title","Different Types of Signal Coupling in the Visual Cortex Related to Neural Mechanisms of Associative Processing and Perception"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","300"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Cerebral Cortex"],["dc.bibliographiccitation.lastpage","313"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Gail, Alexander"],["dc.date.accessioned","2017-09-07T11:47:47Z"],["dc.date.available","2017-09-07T11:47:47Z"],["dc.date.issued","2004"],["dc.description.abstract","Cortical synchronization at γ-frequencies (35–90 Hz) has been proposed to define the connectedness among the local parts of a perceived visual object. This hypothesis is still under debate. We tested it under conditions of binocular rivalry (BR), where a monkey perceived alternations among conflicting gratings presented singly to each eye at orthogonal orientations. We made multi-channel microelectrode recordings of multi-unit activity (MUA) and local field potentials (LFP) from striate cortex (V1) during BR while the monkey indicated his perception by pushing a lever. We analyzed spectral power and coherence of MUA and LFP over 4–90 Hz. As in previous work, coherence of γ-signals in most pairs of recording locations strongly depended on grating orientation when stimuli were presented congruently in both eyes. With incongruent (rivalrous) stimulation LFP power was often consistently modulated in consonance with the perceptual state. This was not visible in MUA. These perception-related modulations of LFP occurred at low and medium frequencies (<30 Hz), but not at γ-frequencies. Perception-related modulations of LFP coherence were also restricted to the low–medium range. In conclusion, our results do not support the expectation that γ-synchronization in V1 is related to the perceptual state during BR, but instead suggest a perception-related role of synchrony at low and medium frequencies."],["dc.identifier.doi","10.1093/cercor/bhg129"],["dc.identifier.gro","3150715"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/7502"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.relation.issn","1460-2199"],["dc.title","Perception-related Modulations of Local Field Potential Power and Coherence in Primary Visual Cortex of Awake Monkey during Binocular Rivalry"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","421"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Journal of Vision"],["dc.bibliographiccitation.lastpage","421"],["dc.bibliographiccitation.volume","12"],["dc.contributor.author","Anton-Erxleben, Katharina"],["dc.contributor.author","Westendorff, Stephanie"],["dc.contributor.author","Treue, Stefan"],["dc.contributor.author","Gail, Alexander"],["dc.date.accessioned","2018-02-26T14:23:21Z"],["dc.date.available","2018-02-26T14:23:21Z"],["dc.date.issued","2012"],["dc.description.abstract","Background: Attention improves the visual system’s spatial resolution and distorts the perception of visual space: Perceived locations are repulsed away from the attentional focus (Suzuki & Cavanagh, 1997). However, little is known about whether and how attention affects visual space in action. Methods: Here, we tested the effects of exogenous attention on visually guided reach movements. Attention was drawn involuntarily to a transient, uninformative cue (white square, 72ms) at one of two locations at 11.4º eccentricity and ±45º polar angle in either the upper left or upper right quadrant, respectively. After a brief delay (56ms), a reach target (green circle, 29ms) appeared at a randomly chosen position along an imaginary half-circle within the upper visual field with the same eccentricity as the cue positions. In the ‘attended’ condition, cue and target appeared within the same quadrant, whereas in the ‘unattended’ condition they appeared in opposite hemifields. For each target location, we calculated the distance between reach endpoint and target for the attended and the unattended condition. Results & Conclusions: In the attended condition, reach endpoints toward targets in the vicinity of the attentional cue were repulsed away from the cue by up to ~0.9º, relative to the unattended condition. The spatial profile of the magnitude of this effect follows an ‘M’-shape centered on the focus of attention; i.e., the cue did not affect reaches toward targets at the cued location or far away from it. Reaction times (target onset to movement start) tended to be slower for targets near the cue, whereas movement times (movement start to landing time) at all locations tended to be faster in the attended than in the unattended condition. These results are consistent with an attentional distortion of visual space and suggest a parallelism between the perception and action systems for the representation of location."],["dc.identifier.doi","10.1167/12.9.421"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/12628"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.title","Attention distorts reach space"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","204"],["dc.bibliographiccitation.lastpage","219"],["dc.bibliographiccitation.volume","11454"],["dc.contributor.author","Unakafov, Anton M."],["dc.contributor.author","Schultze-Gerlach, Thomas"],["dc.contributor.author","Kagan, Igor"],["dc.contributor.author","Moeller, Sebastian"],["dc.contributor.author","Gail, Alexander"],["dc.contributor.author","Treue, Stefan"],["dc.contributor.author","Eule, Stephan"],["dc.contributor.author","Wolf, Fred"],["dc.contributor.editor","Kaufmann, P."],["dc.contributor.editor","Castillo, P."],["dc.date.accessioned","2019-07-30T07:45:17Z"],["dc.date.available","2019-07-30T07:45:17Z"],["dc.date.issued","2019"],["dc.description.abstract","A Transparent game is a game-theoretic setting that takes action visibility into account. In each round, depending on the relative timing of their actions, players have a certain probability to see their partner’s choice before making their own decision. This probability is determined by the level of transparency. At the two extremes, a game with zero transparency is equivalent to the classical simultaneous game, and a game with maximal transparency corresponds to a sequential game. Despite the prevalence of intermediate transparency in many everyday interactions such scenarios have not been sufficiently studied. Here we consider a transparent iterated Prisoner’s dilemma (iPD) and use evolutionary simulations to investigate how and why the success of various strategies changes with the level of transparency. We demonstrate that non-zero transparency greatly reduces the set of successful memory-one strategies compared to the simultaneous iPD. For low and moderate transparency the classical “Win - Stay, Lose - Shift” (WSLS) strategy is the only evolutionary successful strategy. For high transparency all strategies are evolutionary unstable in the sense that they can be easily counteracted, and, finally, for maximal transparency a novel “Leader-Follower” strategy outperforms WSLS. Our results provide a partial explanation for the fact that the strategies proposed for the simultaneous iPD are rarely observed in nature, where high levels of transparency are common."],["dc.identifier.doi","10.1007/978-3-030-16692-2_14"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/62176"],["dc.language.iso","en"],["dc.publisher","Springer"],["dc.publisher.place","hm"],["dc.relation.crisseries","Lecture Notes in Computer Science"],["dc.relation.isbn","978-3-030-16691-5"],["dc.relation.isbn","978-3-030-16692-2"],["dc.relation.ispartof","Applications of Evolutionary Computation. Applications of Evolutionary Computation."],["dc.relation.ispartofseries","Lecture Notes in Computer Science;"],["dc.relation.issn","0302-9743"],["dc.relation.issn","1611-3349"],["dc.title","Evolutionary Successful Strategies in a Transparent iterated Prisoner’s Dilemma"],["dc.type","book_chapter"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Bulletin of the American Physical Society"],["dc.bibliographiccitation.volume","58"],["dc.contributor.author","Witt, Annette"],["dc.contributor.author","Battaglia, Demian"],["dc.contributor.author","Gail, Alexander"],["dc.date.accessioned","2018-02-26T14:17:17Z"],["dc.date.available","2018-02-26T14:17:17Z"],["dc.date.issued","2013"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/12627"],["dc.language.iso","en"],["dc.notes","https://meetings.aps.org/Meeting/MAR13/Event/190986"],["dc.notes.status","fcwi"],["dc.relation.conference","American Physical Society March Meeting"],["dc.relation.eventend","2013-03-22"],["dc.relation.eventlocation","Baltimore, Md"],["dc.relation.eventstart","2013-03-18"],["dc.title","Paradoxical Behavior of Granger Causality"],["dc.type","conference_abstract"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]