Table 1.

Candidate mechanisms linking elevated beta-band activity with excitation-inhibition imbalance

Intrinsic alterations   Inhibitory interneurons maybe more susceptible to: (i) α-syn accumulation,212 and/or (ii) higher excitability due to increased synaptic conductance, i.e. elevated Ca2+ influx via NMDA and Ca2 + channels.211 Larger numbers of interneurons participating in the beta oscillations. Increased oscillatory coherence between interneurons. Top-down alterations   α-Syn accumulation in neighbouring brain regions resulting in compensatory input to interneurons, increasing their spiking. Bottom-up alterations   α-Syn increases conductance of projection neurons, sufficiently exciting the interneurons such that the latter induces a strong inhibitory input silencing the former. Combinations of the above intrinsic, top-down, and bottom-up alterations.