G Deco

..In conclusion, these results suggest that the variability reduction under stimulation and attention is a property of neural circuits...

..The multistable attractor landscape defines a functionally meaningful dynamic repertoire of the brain network that is inherently present in the neuroanatomical connectivity...

..As the regime of balanced inputs has been experimentally observed, these results suggest that this regime is functionally important from an information encoding standpoint...

..In particular, the activity of the model resembles reported data from single-cell recordings in the prefrontal cortex...

..It is shown that the effects of neuromodulation by dopamine of the synaptic processes utilized in the neurons in the model leads to experimental predictions of the effects of manipulations of dopamine on working memory...

..We apply this technique to describe multistable phenomena. We show that increasing the noise amplitude results in a shifting of the bifurcation structure of the system...

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..We conclude that the neurodynamical mechanisms and computational principles underlying the decision-making processes in this perceptual discrimination task are consistent with a fluctuation-driven scenario in a multistable regime...

..Thus, neuronal fluctuations can be an advantage for brain processing because they lead to probabilistic behavior in decision making in this and other sensory tasks...

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..In particular, we are able to explain the asymmetrical effect of spatial cueing on neglect, and the phenomenon of extinction in the framework of visual search...

..We argue that elaborating principled and informed models is a prerequisite for grounding empirical neuroscience in a cogent theoretical framework, commensurate with the achievements in the physical sciences...

..These findings help explain why acetylcholine is necessary for top-down-driven attentional modulation, and suggest a close interdependence of cholinergic and feedback drive in mediating cognitive function...

..Large-scale systems dynamics are useful for keeping different functional subnetworks in a state of heightened competition, which can be stabilized and fired by even small modulations of either sensory or internal signals...

..We propose that the formation and dissolution of resting-state patterns reflects the exploration of possible functional network configurations around a stable anatomical skeleton...

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..Thus the neurophysiological basis for a psychophysical effect, Weber's Law, can be related to statistical fluctuations and divisive inhibition in an attractor decision-making network...

..Both experiment and simulations suggest that the global-precedence effect prevails under the condition of visual search...

..This suggests a major functional role for oscillatory brain activity that has been widely reported experimentally...

..Further, it is shown that, although NMDA nonlinear effects may be useful in attention, they are not necessary, with nonlinear effects (which may appear multiplicative) being produced in the way just described...

..The models also directly address how bottom-up and top-down processes interact in visual cognition, and show how some apparently serial processes reflect the operation of interacting parallel distributed systems...

..Moreover, the high variability activity of MPC neurons both within and between trials reflects stochastic fluctuations that may play a crucial role in the monkey's probabilistic perceptual reports...

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..Under lighter anesthesia, however, the distributions of the times spent in the up and down states were better fitted by such a model, suggesting a role for noise in determining the time spent in a particular state...

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..The computational viability of this architecture was tested by simulating a large-scale neural dynamical network...

..Consequently, our results suggest a physiological advantage of a pooled, multineuron representation of choice alternatives...

..Modular competition and cooperation might constitute general mechanisms for implementing context-dependent formation of working memory...

..The escape mechanism provides thus a dynamical basis for the wide range and variability of decision times observed experimentally...

..Thus, both synaptic facilitation and neuronal attractor dynamics can account for sequential decision making in such systems in the brain...

..We find that a linear change in network parameters relates to the changes in neural activity in consecutive correct trials during learning, which is important evidence for the underlying learning mechanisms...

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..This should be visible not only in the corresponding activity in the premotor area, but also in activity corresponding to other associations or even other stimuli in the prefrontal cortex...

..However, we show that there is an advantage in the processing of information if rate modulation is accompanied by gamma modulation, namely that reaction times are shorter, implying behavioral relevance for gamma synchronization...

..We find that for different levels of sensory evidence favoring one of the two interpretations of the ambiguous stimulus, higher levels of neural adaptation lead to quicker decisions contributing to a speed-accuracy trade off...

..The results of the present study are compared with those obtained in short-term laboratory exposures in an attempt to provide an integrative account...

..We conclude that subjects often exposed to dialectal word variations can store these in their lexicons, without altering their phoneme representations...

..We describe how these stochastic neurodynamical effects can be analyzed, and their importance in many aspects of brain function, including decision-making, memory recall, short-term memory, and attention...

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..Our neurodynamical model is used to numerically compute the neural activity of area V4 corresponding to such ignored stimulus, giving a good description of the experimental data...

..The proposed model draws together data of different spatial and temporal resolution, as are the above-mentioned imaging and single-cell results...

..Finally, we also reveal parameter regimes where the network has different modes of operation: selective working memory, attentional filtering, pure competition and noncompetitive amplification...

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..The network thus uses adaptation rather than associative synaptic modification to recall the order of the items in a recently presented sequence...

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..We conclude that the perceptual representation in visual areas like ITC can be strongly affected by the interaction with other areas which are devoted to higher cognitive functions...

..The results indicate that the sSoTS model can provide a biologically plausible account of human search over time as well as space...

..The operation of the model thus demonstrates with at least a high probability the neuronal dynamics underlying a key component of human behavior: the ability to adapt behavior according to context requirements--cognitive flexibility...

..Our results thus provide an existence proof of the feasibility of novel theoretical models and provide a mechanism to explain various psychophysical and physiological results...

..Neural computation has to exploit the itinerant dynamics between these states...

..Computational models of this processing are described...

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