However, such precision is not present on the level of a single muscle. The functional role of synchronization can be seen at all levels of psychological reality: brain function, perception, motor behavior, higher-order action, mental processes, dyadic behavior, and collective action in social groups. Synchronization plays a crucial role in how the brain performs its functions.
Brain function requires both the segregation and integration of information, whether sensory or retrieved from memory. With the development of techniques for visualizing brain activity, we know relatively well how the brain segregates such information by specifying distinct regions for processing specific types of information.
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Our knowledge about how the brain integrates information, however, is much more limited. The leading hypothesis relates information integration to synchronization between regions processing different types of information e. Synchronized activity of neural assemblies in the brain is theorized to be important to the performance of sensory and perceptual functions von der Malsburg, Synchronized oscillations between brain regions have been observed in motor and cognitive functions, specifically in conscious processing von der Malsburg, ; Tononi et al. Sensation of the simplest object requires the synchronized activity of neural ensembles cf.
Moreover, long-range synchrony between distant brain regions is observed in multiple forms of behavior Harris and Gordon, Correlation code is also thought to underlie selective attention Niebur et al. To understand how synchronization of neural activity could fulfill the role of information integration, we need to realize what a daunting task it is to combine inputs from so many dispersed and functionally distinct sources.
The binding problem represents the prototypical challenge for integration of information in the brain. If a person is perceiving a blue circle and a red square for example, how does the brain bind the shape and color features to form a representation of the object? In other words, how does the brain know that the circle is blue and the square is red?
Singer and Gray proposed that temporal characteristics of the neural activity are responsible for the binding, such that all the neuronal groups coding different features of the same object will synchronize their activity to within the range of milliseconds. This process enables integration of multiple features and the concurrent performance of multiple perceptual functions, such as the integration of features into several distinct objects. This can be achieved by using distinct temporal patterns e. The same mechanism may explain hierarchical organization, where one group of neurons belongs to more than one integrative unit at the same time e.
The temporal correlation hypothesis also explains how integrated wholes may interact at higher levels of information processing, as synchronized neural assemblies form a functional unit at a higher level, which is distinguishable from other neural assemblies because of its particular temporal pattern.
Synchronized neural assemblies are more visible than are unsynchronized assemblies, even if the former are smaller, because a neuron is much more likely to produce an action potential if the incoming signals from its input neurons are synchronized. Such binding must occur across virtually all modalities: auditory binding may be needed to discriminate the sound of a single voice in the crowd, and binding across time is required to perceive the motion of the object.
A cross-modal binding is required to associate the sound of a ball striking a bat with the visual percept of it, so both can be perceived as different aspects of the same event. Cognitive binding, for example, must link visual perception of an object with its semantic knowledge, memory reconstruction, and cross modal identification see Neuron, 24 , , for a review.
Synchronized activity is mostly visible and recorded as synchronous oscillations in the electrical activity between various brain regions.
At each level of information processing, synchronized groups form functional units that integrate into increasingly complex structures. These neuronal groups from different brain regions may correspond, for example, to personal memories, affective reactions, and so forth, with respect to the object. Each assembly at a lower level may be responsible for detecting specific features of the stimulus, but it is the synchronized representation of the various assemblies that gives rise to conscious awareness of the object.
Such a synchronized neural group is similar to the notion of cell assembly , as proposed by Hebb , in which intragroup connections facilitate activation of the entire group when a single neuron is activated.
The temporal correlation hypothesis does not require the formation of stable structural connections, but rather proposes that temporal strengthening of synapses LTP—long-term potentiation may also be responsible for the creation of a synchronized functional unit. Functional units are therefore dynamical formations appearing for a short time and disassembling shortly thereafter, allowing for the creation of new functional units Rychwalska, To a certain extent, the interaction among elements may also change on an even more intermittent basis due to changes in focus of attention e.
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Attention, in other words, brings together diverse groups of neurons that then have the opportunity to synchronize with one another. Such high integration requires long-range correlations and complex temporal patterns of coordination. In other words, functional binding between distinct neural assembles has to be highly flexible, enabling the functional cluster to move through a sequence of distinct states without losing its synchronization Koch et al.
Nakatani et al. At the same time, loss of consciousness itself e. Once conscious representations are formed in accordance with the scenario outlined above , they become elements subject to further integration processes that result in higher order mental structures such as action representations, judgments, and self-concepts. As with the brain, synchronization plays a crucial role in this process. If the process of progressive integration can maintain synchronization among a subset of elements, it proceeds until a cognitive function is performed e.
Considerable research has established that coherence is indeed a basic principle in cognitive function and structure cf. Abelson et al. Within this framework, a variety of mechanisms have been identified whose function is to maintain coherence in the face of incongruent information or social influence e.
Tesser et al. The nature of the cognitive function dictates the specific metric by which coherence is assessed. In forming a judgment of someone, the function is the establishment of an unequivocal behavior orientation toward the person cf. Jones and Gerard, In self-understanding, the function is self-assessment cf. Tesser and Campbell, In action representation, the function is effective performance cf.
Vallacher and Wegner, In each case, the issue of coherence is how well the elements support each other i. Thus, a coherent social judgment is one in which all the activated cognitive elements are consistent in their implications for evaluation of the target. In self-understanding, meanwhile, a coherent self-concept is one in which activated self-relevant information paints the same evaluative portrait.
conglamoliri.ga And in action, a representation is effective to the extent that the lower-level action features synchronize to produce a fluid performance cf. Vallacher et al. When coherence among elements cannot be achieved in the process of progressive integration, control mechanisms disassemble the emerging structure and attempt to coordinate the elements or a new set of elements. This process may be repeated until the function is achieved i.
A new function, in other words, may emerge from the disassembly and subsequent reconfiguration of cognitive elements Vallacher et al. The functioning of mind may thus be described as the continual assembly and disassembly of cognitive elements in the search for coherence. The stream of consciousness may ultimately be a tumbling ground for whimsies James, , but this very feature of thought enables the emergence of structure and effective function.
The progressive assembly and disassembly of system elements is reflected in the temporal trajectory of emergent thought. In social judgment, for example, univalent evaluatively congruent information is organized into progressively higher level structures reflecting increased coherence, a scenario that is reflected in thought-induced attitude polarization Tesser, Mixed valence information, however, tends to result in the repeated assembly and disassembly of differently valenced elements in a process of dynamic integration cf.
The process of progressive integration has also been observed with respect to self-reflection, with individuals who are instructed to focus on the details of their action displaying increasing oscillations in their self-evaluations during self-reflective thought, indicative of the assembly of progressively higher-order evaluatively coherent structures Vallacher and Nowak, ; Vallacher et al. From the perspective of synchronization, coherence of cognitive representations is fundamental.
Coherent representations will be integrated into higher-order representations, while incoherent ones will either be disintegrated or will have their incoherent parts eliminated in the process of integration. From this standpoint, the signals of coherence are global cross-modal signals. Coherence in one sensory modality favors progressive information integration in other modalities; incoherence in one modality disrupts signal integration taking place in different modality.
Research has shown that watching incoherent figures evokes a sensation that a musical selection does not follow familiar principles, while watching coherent figures facilitates the feeling that such music is familiar Ziembowicz et al. Despite the deep roots of this perspective in classic treatments of mind e. Connectionism has emerged in recent years as the tool of choice in investigating how systems resolve conflict and maximize coherence cf. Read and Miller, Thus, the function of cognitive networks is assumed to be the satisfaction of multiple constraints represented by connections , such that the network achieves a configuration in which the states of nodes are least conflictful.
Although connectionist models can solve the coherence problem, they have an important limitation with respect to modeling the scenario we have described.
In particular, most models are limited to a single step, in that once a coherent solution has been achieved, the system is trapped in this state and does not evolve further. The mental content and structures that emerge in line with the synchronization scenario outlined above provide the basis for overt behavior in the context of environmental constraints, challenges, concerns, and personal goals. This scenario of repeated assembly and disassembly of mental representations in service of effective action is central to action identification theory Vallacher and Wegner, The theory holds that effective performance of an action is associated with progressive integration of the lower-level structural elements of the action.
A novice tennis player, for example, is likely to identify his or her behavior in terms of the basic acts involved—adjusting body position, swinging the racket, and so forth. By the same token, if the action becomes ineffective when identified at a particular level of identification, the person is likely to shift to a lower-level identification that reflects the basic structural elements of the action.
The tennis player who fails to play tennis effectively, for example, may regain mental control of the action by refocusing his or her conscious attention on shifting his or her body position and swinging the racket. The emphasis on the cognitive representation of action in this scenario may seem at odds with a large body of research on behavioral coordination e. Researchers in this area have emphasized that reactions to changing environmental circumstances and skill acquisition do not require conscious mental representations. Instead, there is a direct coupling of perception and action, such that environmental affordances are registered at a perceptual level without the need for higher-level cognitive interpretation.
Environmental affordances also shape motor reactions through coupling of behavior and perception, such that refined and skillful enactment of behavior leads to finer distinctions in the perception of the context in which the action unfolds. This perspective holds that in developing a motor skill, the specific movements become coupled, so that the system as a whole loses degrees of freedom e. So although hundreds of muscles are involved in even such an act as shaking hands, for example, it is unlikely that the central nervous system could cognitively cope with the control of each muscle.
These patterns of mutual constraint are flexible, changing in accordance with the requirements of the function.