1,355 research outputs found
Sensorimotor coordination and metastability in a situated HKB model
Oscillatory phenomena are ubiquitous in nature and have become particularly relevant for the study of brain and behaviour. One of the simplest, yet explanatorily powerful, models of oscillatory Coordination Dynamics is the Haken–Kelso–Bunz (HKB) model. The metastable regime described by the HKB equation has been hypothesised to be the signature of brain oscillatory dynamics underlying sensorimotor coordination. Despite evidence supporting such a hypothesis, to our knowledge, there are still very few models (if any) where the HKB equation generates spatially situated behaviour and, at the same time, has its dynamics modulated by the behaviour it generates (by means of the sensory feedback resulting from body movement). This work presents a computational model where the HKB equation controls an agent performing a simple gradient climbing task and shows (i) how different metastable dynamical patterns in the HKB equation are generated and sustained by the continuous interaction between the agent and its environment; and (ii) how the emergence of functional metastable patterns in the HKB equation – i.e. patterns that generate gradient climbing behaviour – depends not only on the structure of the agent's sensory input but also on the coordinated coupling of the agent's motor–sensory dynamics. This work contributes to Kelso's theoretical framework and also to the understanding of neural oscillations and sensorimotor coordination
Dwelling Quietly in the Rich Club: Brain Network Determinants of Slow Cortical Fluctuations
For more than a century, cerebral cartography has been driven by
investigations of structural and morphological properties of the brain across
spatial scales and the temporal/functional phenomena that emerge from these
underlying features. The next era of brain mapping will be driven by studies
that consider both of these components of brain organization simultaneously --
elucidating their interactions and dependencies. Using this guiding principle,
we explored the origin of slowly fluctuating patterns of synchronization within
the topological core of brain regions known as the rich club, implicated in the
regulation of mood and introspection. We find that a constellation of densely
interconnected regions that constitute the rich club (including the anterior
insula, amygdala, and precuneus) play a central role in promoting a stable,
dynamical core of spontaneous activity in the primate cortex. The slow time
scales are well matched to the regulation of internal visceral states,
corresponding to the somatic correlates of mood and anxiety. In contrast, the
topology of the surrounding "feeder" cortical regions show unstable, rapidly
fluctuating dynamics likely crucial for fast perceptual processes. We discuss
these findings in relation to psychiatric disorders and the future of
connectomics.Comment: 35 pages, 6 figure
Neuronal assembly dynamics in supervised and unsupervised learning scenarios
The dynamic formation of groups of neurons—neuronal assemblies—is believed to mediate cognitive phenomena at many levels, but their detailed operation and mechanisms of interaction are still to be uncovered. One hypothesis suggests that synchronized oscillations underpin their formation and functioning, with a focus on the temporal structure of neuronal signals. In this context, we investigate neuronal assembly dynamics in two complementary scenarios: the first, a supervised spike pattern classification task, in which noisy variations of a collection of spikes have to be correctly labeled; the second, an unsupervised, minimally cognitive evolutionary robotics tasks, in which an evolved agent has to cope with multiple, possibly conflicting, objectives. In both cases, the more traditional dynamical analysis of the system’s variables is paired with information-theoretic techniques in order to get a broader picture of the ongoing interactions with and within the network. The neural network model is inspired by the Kuramoto model of coupled phase oscillators and allows one to fine-tune the network synchronization dynamics and assembly configuration. The experiments explore the computational power, redundancy, and generalization capability of neuronal circuits, demonstrating that performance depends nonlinearly on the number of assemblies and neurons in the network and showing that the framework can be exploited to generate minimally cognitive behaviors, with dynamic assembly formation accounting for varying degrees of stimuli modulation of the sensorimotor interactions
Temporal structure of neural oscillations underlying sensorimotor coordination: a theoretical approach with evolutionary robotics
The temporal structure of neural oscillations has become a widespread hypothetical
\mechanism" to explain how neurodynamics give rise to neural functions. Despite the
great number of empirical experiments in neuroscience and mathematical and computa-
tional modelling investigating the temporal structure of the oscillations, there are still
few systematic studies proposing dynamical explanations of how it operates within closed
sensorimotor loops of agents performing minimally cognitive behaviours. In this thesis
we explore this problem by developing and analysing theoretical models of evolutionary
robotics controlled by oscillatory networks. The results obtained suggest that: i) the in-
formational content in an oscillatory network about the sensorimotor dynamics is equally
distributed throughout the entire range of phase relations; neither synchronous nor desyn-
chronous oscillations carries a privileged status in terms of informational content in relation
to an agent's sensorimotor activity; ii) although the phase relations of oscillations with
a narrow frequency difference carry a relatively higher causal relevance than the rest of
the phase relations to sensorimotor coordinations, overall there is no privileged functional
causal contribution to either synchronous or desynchronous oscillations; and iii) oscilla-
tory regimes underlying functional behaviours (e.g. phototaxis, categorical perception) are
generated and sustained by the agent's sensorimotor loop dynamics, they depend not only
on the dynamic structure of a sensory input but also on the coordinated coupling of the
agent's motor-sensory dynamics. This thesis also contributes to the Coordination Dynam-
ics framework (Kelso, 1995) by analysing the dynamics of the HKB (Haken-Kelso-Bunz)
equation within a closed sensorimotor loop and by discussing the theoretical implications
of such an analysis. Besides, it contributes to the ongoing philosophical debate about
whether actions are either causally relevant or a constituent of cognitive functionalities by
bringing this debate to the context of oscillatory neurodynamics and by illustrating the
constitutive notion of actions to cognition
Coordination dynamics in the sensorimotor loop
The last two decades have witnessed radical changes of perspective about the nature of intelligence and cognition, leaving behind some of the assumptions of computational functionalism. From the myriad of approaches seeking to substitute the old rule-based symbolic perception of mind, we are especially interested in two of them. The first is Embodied and Situated Cognition, where the advances in modeling complex adaptive systems through computer simulations have reconfigured the way in which mechanistic, embodied and interactive explanations can conceptualize the mind. We are particularly interested in the concept of sensorimotor loop, which brings a new perspective about what is needed for a meaningful interaction with the environment, emphasizing the role of the coordination of effector and sensor activities while performing a concrete task. The second one is the framework of Coordination Dynamics, which has been developed as a result of the increasing focus of neuroscience on self-organized oscillatory brain dynamics. It provides formal tools to study the mechanisms through which complex biological systems stabilize coordination states under conditions in which they would otherwise become unstable. We will merge both approaches and define coordination in the sensorimotor loop as the main phenomena behind the emergence of cognitive behavior. At the same time, we will provide methodological tools and concepts to address this hypothesis. Finally, we will present two case studies based on the proposed approach: 1. We will study the phenomenon known as “intermittent behavior”, which is observed in organisms at different levels (from microorganisms to higher animals). We will propose a model that understands intermittent behavior as a general strategy of biologica organization when an organism has to adapt to complex changing environments, and would allow to establish effective sensorimotor loops even in situations of instable engagement with the world. 2. We will perform a simulation of a phonotaxis task performed by an agent with an oscillator network as neural controller. The objective will be to characterize robust adaptive coupling between perceptive activity and the environmental dynamics just through phase information processing. We will observe how the robustness of the coupling crucially depends of how the sensorimotor loop structures and constrains both the emergent neural and behavioral patterns. We will hypothesize that this structuration of the sensorimotor space, in which only meaningful behavioral patterns can be stabilized, is a key ingredient for the emergence of higher cognitive abilities
Perspectives on the Neuroscience of Cognition and Consciousness
The origin and current use of the concepts of computation, representation and information in Neuroscience are examined and conceptual flaws are identified which vitiate their usefulness for addressing problems of the neural basis of Cognition and Consciousness. In contrast, a convergence of views is presented to support the characterization of the Nervous System as a complex dynamical system operating in the metastable regime, and capable of evolving to configurations and transitions in phase space with potential relevance for Cognition and Consciousness
Analysis of Embodied and Situated Systems from an Antireductionist Perspective
The analysis of embodied and situated agents form a dynamical system perspective is often
limited to a geometrical and qualitative description. However, a quantitative analysis is necessary
to achieve a deep understanding of cognitive facts.
The field of embodied cognition is multifaceted, and the first part of this thesis is devoted to exploring
the diverse meanings proposed in the existing literature. This is a preliminary fundamental
step as the creation of synthetic models requires well-founded theoretical and foundational
boundaries for operationalising the concept of embodied and situated cognition in a concrete
neuro-robotic model. By accepting the dynamical system view the agent is conceived as highly
integrated and strictly coupled with the surrounding environment. Therefore the antireductionist
framework is followed during the analysis of such systems, using chaos theory to unveil global
properties and information theory to describe the complex network of interactions among the
heterogeneous sub-components.
In the experimental section, several evolutionary robotics experiments are discussed. This class
of adaptive systems is consistent with the proposed definition of embodied and situated cognition.
In fact, such neuro-robotics platforms autonomously develop a solution to a problem exploiting
the continuous sensorimotor interaction with the environment.
The first experiment is a stress test for chaos theory, a mathematical framework that studies erratic
behaviour in low-dimensional and deterministic dynamical systems. The recorded dataset
consists of the robots’ position in the environment during the execution of the task. Subsequently,
the time series is projected onto a multidimensional phase space in order to study the underlying
dynamic using chaotic numerical descriptors. Finally, such measures are correlated and confronted
with the robots’ behavioural strategy and the performance in novel and unpredictable
environments.
The second experiment explores the possible applications of information-theoretic measures for
the analysis of embodied and situated systems. Data is recorded from perceptual and motor
neurons while robots are executing a wall-following task and pairwise estimations of the mutual
information and the transfer entropy are calculated in order to create an exhaustive map of the
nonlinear interactions among variables. Results show that the set of information-theoretic employed
in this study unveils characteristics of the agent-environemnt interaction and the functional
neural structure.
This work aims at testing the explanatory power and impotence of nonlinear time series analysis
applied to observables recorded from neuro-robotics embodied and situated systems
Linking embodied coordination dynamics and subjective experiences in musical interactions : a renewed methodological paradigm
Embodied music cognition provides a valuable and comprehensive research paradigm within systematic musicology to describe and explain musical sense-making. The basic claim underlying musical embodiment is that subjective meaning, in its broadest sense, is actively constructed within humans’ bodily interaction with music. As such, the empirical study of bodily coordination may provide insights into the subjective aspects of musical experiences. In the present paper, we advocate for a dynamical systems approach to human music interaction, focusing on the time-varying principles, and the relational aspects of the musical interaction process. We propose a model that integrates these focus points, to investigate the link between embodied coordination dynamics, subjective experience and sense-making. We then discuss possible quantitative and qualitative techniques that allow to operationalise the model into concrete empirical music research. Finally, we conclude by presenting some illustrative research cases conducted at IPEM, Ghent University institute for systematic musicology
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