Power Fluctuations in Beta and Gamma Frequencies in Rat Globus Pallidus: Association with Specific Phases of Slow Oscillations and Differential Modulation by Dopamine D₁and D₂Receptors

Abstract

Modulation of oscillatory activity through basal ganglia-cortical loops in specific frequency bands is thought to reflect specific functional states of neural networks. A specific negative correlation between beta and gamma sub-bands has been demonstrated in human basal ganglia and may be key for normal basal ganglia function. However, these studies were limited to Parkinson's disease patients. To confirm that this interaction is a feature of normal basal ganglia, we recorded local field potential (LFP) from electrodes in globus pallidus (GP) of intact rats. We found significant negative correlation between specific frequencies within gamma (Ϸ60 Hz) and beta (Ϸ14 Hz) bands. Furthermore, we show that fluctuations in power at these frequencies are differentially nested within slow (Ϸ3 Hz) oscillations in the delta band, showing maximum power at distinct and different phases of delta. These results suggest a hierarchical organization of LFP frequencies in the rat GP, in which a low-frequency signal in the basal ganglia can predict the timing and interaction of power fluctuations across higher frequencies. Finally, we found that dopamine D 1 and D 2 receptor antagonists differentially affected power in gamma and beta bands and also had different effects on correlation between them and the nesting within delta, indicating an important role for endogenous dopamine acting on direct and indirect pathway neurons in the maintenance of the hierarchical organization of frequency bands. Disruption of this hierarchical organization and subsequent disordered beta-gamma balance in basal ganglia disorders such as Parkinson's disease may be important in the pathogenesis of their symptoms.

Habit learning is associated with major shifts in frequencies of oscillatory activity and synchronized spike firing in striatum

“…Our findings establish that β-band oscillations in the VMS occur predominantly in brief, approximately 100-to 200-ms bursts. We found no evidence for prolonged periods of β-oscillations when we analyzed the data trial by trial, consonant with findings by Dejean et al (19). Remarkably, the β-bursts that we observed directly corresponded to transient episodes in which the spikes of striatal FSIs and projection neurons were synchronized to the β-band oscillations.…”

Systemic Blockade of Dopamine D2-Like Receptors Increases High-Voltage Spindles in the Globus Pallidus and Motor Cortex of Freely Moving Rats

“…The present study observed that dopamine D 2 -like receptor antagonists, but not D 1 -like receptor antagonists, increased the power of HVS activity in the M1 cortex and LFP of the GP, indicating that D 2 -like receptors play a role in the modulation of HVSs. This is in line with previous findings which suggest that dopamine D 2 -like receptors may have a special role in the regulation of BG rhythmic activity via dopamine [29]. As the GP comprises extensive local axon collaterals, and projects to all other BG nuclei, it is considered to be central in propagating and synchronizing oscillatory activity in the cortical–BG networks [30], [31], [32].…”

Basal Ganglia Beta Oscillations Accompany Cue Utilization

“…We have previously reported that striatal LFPs show mutually exclusive dynamic states, characterized by combinations of either ~20 Hz beta and ~50 Hz low-gamma rhythms, or ~8 Hz theta and ~80 Hz high-gamma rhythms, respectively (Berke, 2009; see also Dejean et al, 2011). These distinct states were visible in our current comodulograms: in STR, GP, and STN ~50 Hz power was positively correlated with beta power and negatively correlated with ~80 Hz activity.…”