Delta-mediated cross-frequency coupling organizes oscillatory activity across the rat cortico-basal ganglia network

Abstract

The brain's ability to integrate different behavioral and cognitive processes relies on its capacity to generate neural oscillations in a cooperative and coordinated manner. Cross-frequency coupling (CFC) has recently been proposed as one of the mechanisms involved in organizing brain activity. Here we investigated the phase-to-amplitude CFC (PA-CFC) patterns of the oscillatory activity in the cortico-basal ganglia network of healthy, freely moving rats. Within-structure analysis detected consistent PA-CFC patterns in the four regions analyzed, with the phase of delta waves modulating the amplitude of activity in the gamma (low-gamma ~50 Hz; high-gamma ~80 Hz) and high frequency ranges (high frequency oscillations HFO, ~150 Hz). Between-structure analysis revealed that the phase of delta waves parses the occurrence of transient episodes of coherence in the gamma and high frequency bands across the entire network, providing temporal windows of coherence between different structures. Significantly, this specific spatio-temporal organization was affected by the action of dopaminergic drugs. Taken together, our findings suggest that delta-mediated PA-CFC plays a key role in the organization of local and distant activities in the rat cortico-basal ganglia network by fine-tuning the timing of synchronization events across different structures.

Ventral striatal gamma oscillations are highly variable from trial to trial, and are dominated by behavioural state, and only weakly influenced by outcome value

“…PAC with the theta and alpha rhythms was generally similar in magnitude and preferred phase, which was reversed as compared with the preferred delta phase. These results add to the emerging sense that PAC is a ubiquitous feature of cortico‐striatal loops (Lopez‐Azcarate et al ., ), as well as of inputs specific to the vStr. We found statistically significant differences in the PAC of high‐gamma power to the delta rhythm, depending on outcome value.…”

Beyond the Connectome: The Dynome

“…Most notably, low frequency delta rhythms (1–4 Hz) are known to coordinate large portions of the brain (Fujisawa & Buzsaki, 2011; Nacher et al , 2013). Some of this coordination is done through subcortical structures, notably the thalamus and the basal ganglia (Amzica & Steriade, 1998; Lopez-Azcarate et al , 2013; Antzoulatos & Miller, 2014). …”

Brain Rhythms Connect Impaired Inhibition to Altered Cognition in Schizophrenia

“…In the ventral striatum, schizophrenia-associated abnormalities may decrease hippocampal θ modulation [113, 114]. In rat dorsal striatum, dopamine agonism changes low-frequency phase modulation of high frequency power from the δ to the θ band [115], suggesting coordination with hippocampus rather than PFC [109]. This is intriguing, given the dorso-ventral gradient of functional hypo- to hyperconnectivity with frontal cortex observed in the striatum in schizophrenia [116]: in ventral striatum, decreased hippocampal input may be tied to increased cortical input, while similar mechanisms may have opposite effects in dorsal striatum, contributing to an altered interplay between cortical and limbic influences on striatum [117].…”