Trends in Neurosciences
ReviewNeural Cross-Frequency Coupling: Connecting Architectures, Mechanisms, and Functions
Section snippets
Mechanistic and Functional Characteristics of Cross-Frequency Coupling
Brain oscillations are observed in vivo and in vitro in almost any neuronal population of the neo- and paleocortex. While it is relatively easy to measure oscillations and observe their modulations in various sensory states and cognitive operations, it remains largely unclear what role, if any, they play in neural information processing or, more generally, in cognition 1, 2. An intriguing feature of neural oscillations is that rhythms of distinct frequencies show specific coupling properties 3,
Multi-Item or Sequence Encoding
Many neural systems need to concurrently maintain active representations of distinct items, while avoiding interferences: these can be objects in the visual field, items in working memory, or sequences of motor commands in a complex movement [4]. Neural oscillations offer a potentially efficient tool for multi-item representation by temporally clustering spikes pertaining to each item within distinct oscillations phases. This principle allows downstream neural systems to read-out a given item
Synchronization of Fast Oscillations for Long-Distance Communication
One of the most prominent roles assigned to neural oscillations is to mediate selective neural communication between areas, with in-phase regions communicating more efficiently than out-of-phase ones [73]. Gamma rhythms have predominantly been implicated in this so-called ‘communication through coherence’ mechanism, especially for bottom-up processes [74]. However, fast oscillations only synchronize at a local scale. By contrast, slower rhythms (<10 Hz) may synchronize between distant areas 75,
Temporal Parsing of Continuous Stimuli
Many biological stimuli are characterized by an intrinsic quasi-rhythmic temporal structure, or are processed in a rhythmic mode. Speech is marked with syllabic contours, odors are sniffed at the respiratory rhythm, visual scenes are explored at the pace of saccades, etc. 81, 82. While slow oscillations in sensory areas reflect the rhythm of the sensory signal or of sensory sampling, fast gamma oscillations underpin fine-grained sensory processing in a bottom-up fashion 28, 39, 74, 83. The
Concluding Remarks
The coupling between neural oscillations may take a variety of forms, emerge from different architectures, and underpin distinct functions. However, causal relationships between neural CFC and cognitive functions are yet to be demonstrated. We hope that, by clarifying the concepts and the relationships between mechanisms and function, the framework we outlined here will stimulate original research and hence contribute to filling conceptual and empirical gaps. Essential future developments in
Glossary
- Amplitude–amplitude coupling (AAC)
- coupling between the amplitudes of a slow oscillation (SO) and a fast oscillation (FO).
- Cross-frequency coupling (CFC)
- dynamical interactions between neural oscillations operating in different frequency bands.
- Dense-spiking oscillation
- oscillation generated by synchrony in a neural population in which each neuron in the population emits one spike per cycle at a specific phase.
- Interneuronal gamma (ING) oscillation
- gamma neural oscillation (>30 Hz) arising from
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