A Neural Basis for Perceptual Dynamics

Hock, Howard S.; Schöner, Gregor

doi:10.1007/978-3-642-16262-6_7

Cited by 6 publications

(6 citation statements)

References 34 publications

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“…Such hysteresis effects are signatures of state-dependent neural dynamics (Hock and Schöner, 2010;Hock et al, 2003;Wilson, 1999). Accordingly, perception at any moment in time depends not only on stimulus-initiated detector activation, but also on the immediately preceding activation state of the ensembles of detectors that are activated by the stimulus.…”

Section: Perceptual Hysteresismentioning

confidence: 96%

Measuring Perceptual Hysteresis with the Modified Method of Limits: Dynamics at the Threshold

Hock¹,

Schöner²

2010

Seeing and Perceiving

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This article describes modifications to the psychophysical method of limits that eliminate artifacts associated with the classical method, and thereby indicate whether or not there is perceptual hysteresis. Such hysteresis effects, which are characteristic of dynamical systems, would provide evidence that the near-threshold perception of an attribute is affected by stabilization mechanisms intrinsic to individual neural detectors, and by nonlinear interactions that functionally integrate the detectors when there is sufficient stimulus-initiated activation, thereby stabilizing activation at suprathreshold levels. The article begins with a review of research employing the modified method of limits. It concludes with a model and computational simulations showing how detection instabilities inherent in neural dynamics can create 'activational gaps' between the functionally-integrated and functionally-independent states of neural ensembles, resulting in clear and distinct discrimination between the perception and non-perception of an attribute. The 'self-excitation' threshold for engaging such functionally-integrating detector interactions is differentiated from the traditional 'read-out' threshold (criterion) that determines whether or not the attribute in question can be perceived.

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Section: Perceptual Hysteresismentioning

confidence: 96%

Measuring Perceptual Hysteresis with the Modified Method of Limits: Dynamics at the Threshold

Hock¹,

Schöner²

2010

Seeing and Perceiving

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“…How such changes map onto phase flow patterns remains to be seen, however. Regardless, visual perception have been shown to exhibit characteristics pertaining to attractor dynamics (such as multistability and hysteresis, [54] , [55] ). The corresponding perceptual stability has been shown to depend on (biophysical) processes that stabilize the activation of individual neurons in ensembles of detectors and excitatory and inhibitory interactions among them [54] .…”

Section: Discussionmentioning

confidence: 99%

Complex Processes from Dynamical Architectures with Time-Scale Hierarchy

2011

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The idea that complex motor, perceptual, and cognitive behaviors are composed of smaller units, which are somehow brought into a meaningful relation, permeates the biological and life sciences. However, no principled framework defining the constituent elementary processes has been developed to this date. Consequently, functional configurations (or architectures) relating elementary processes and external influences are mostly piecemeal formulations suitable to particular instances only. Here, we develop a general dynamical framework for distinct functional architectures characterized by the time-scale separation of their constituents and evaluate their efficiency. Thereto, we build on the (phase) flow of a system, which prescribes the temporal evolution of its state variables. The phase flow topology allows for the unambiguous classification of qualitatively distinct processes, which we consider to represent the functional units or modes within the dynamical architecture. Using the example of a composite movement we illustrate how different architectures can be characterized by their degree of time scale separation between the internal elements of the architecture (i.e. the functional modes) and external interventions. We reveal a tradeoff of the interactions between internal and external influences, which offers a theoretical justification for the efficient composition of complex processes out of non-trivial elementary processes or functional modes.

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“…Detection instability Global-to-local feedback that is strong enough to overcome the effects of cross-direction inhibition is initiated in the model when there is sufficient feedforward activation from rotation-consistent local motion detectors for global activation to cross the self-excitation threshold and create a detection instability (Bicho et al, 2000;Hock & Schöner, 2010, 2011Johnson et al, 2009;Schneegans & Schöner, 2008;Schöner, 2008). A recursive feedback loop is initiated in which global-to-local feedback increases the activation of rotation-consistent local motions, which, in turn increases the local-to-global feedforward activation that boosts global activation, and so on.…”

Section: Methodsmentioning

confidence: 99%

“…Whether hierarchical global rotation or global parallel-path motion is perceived depends on whether the activation of the rotation-consistent local motion detectors is sufficiently boosted by the excitatory feedforward/feedback loop to overcome the effects of cross-direction inhibition both within and between the motion quartets. Global-to-local feedback would thereby create a detection instability (Bicho, Mallelt, & Schöner, 2000;Hock & Schöner, 2011;Johnson, Spencer, & Schöner, 2009;Schneegans & Schöner, 2008;Schöner, 2008), which implies a selfexcitation threshold in addition to the read-out threshold that determines whether or not activation is sufficient for motion to be perceived (Hock & Schöner, 2010). Either activation remains below the self-excitation threshold (and thereby, the read-out threshold as well), or it is sufficient to pass through the self-excitation threshold and initiate an activation-stabilizing feedforward/feedback loop.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

“…The proportion of switches from global rotational rocking to global parallel-path motion is indicated for descending trials by the inverted vertical axis on the right rocking or global parallel-path motion patterns are formed depends on the relative strength of global-to-local feedback versus long-range, cross-direction inhibition. (4) The initiation of global-to-local feedback and the stabilization of the hierarchical rotation pattern at both global and local levels requires that the activation of the global detectors pass through a detection instability, as described in the introduction (Bicho et al, 2000;Hock & Schöner, 2010, 2011Johnson et al, 2009;Schneegans & Schöner, 2008;Schöner, 2008). The self-excitation threshold for the detection instability can be exceeded when weak activation of local detectors is supplemented by stochastic fluctuations.…”

Section: The Dynamical Modelmentioning

confidence: 99%

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The temporal dynamics of global-to-local feedback in the formation of hierarchical motion patterns: psychophysics and computational simulations

Hock

Schöner

Brownlow

et al. 2011

Atten Percept Psychophys

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Four motion quartets, each ambiguous with respect to the perception of parallel-path horizontal or vertical motion, were arranged in a diamond configuration. Both global parallel-path motion (the same motion axis for all the quartets), which is typical for multiquartet stimuli, and global rotational rocking are perceived. Experiment 1 indicated that rotational rocking is established at different levels of processing. Globally, larger displacements of each quartet's elements increase the angle of rotation and, thereby, the perception of rotational rocking. Locally, larger displacements have the opposite effect, weakening motion percepts. Experiment 2 showed that global-to-local feedback affects the local perception of rotation-consistent versus rotation-inconsistent motion directions. Experiment 3 provided evidence for hysteresis effects indicative of competition between global rotational rocking and parallel-path motion. The experimental results were simulated by a two-level dynamical model incorporating global-to-local feedback, with recurrent feedforward/feedback loops creating detection instabilities that amplify activation at both global and local levels of the rotational-rocking pattern.

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A Neural Basis for Perceptual Dynamics

Cited by 6 publications

References 34 publications

Measuring Perceptual Hysteresis with the Modified Method of Limits: Dynamics at the Threshold

Measuring Perceptual Hysteresis with the Modified Method of Limits: Dynamics at the Threshold

Complex Processes from Dynamical Architectures with Time-Scale Hierarchy

The temporal dynamics of global-to-local feedback in the formation of hierarchical motion patterns: psychophysics and computational simulations

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