Abstract
Striatal projection neurons form a sparsely-connected inhibitory network, and this arrangement may be essential for the appropriate temporal organization of behavior. Here we show that a simplified, sparse inhibitory network of Leaky-Integrate-and-Fire neurons can reproduce some key features of striatal population activity, as observed in brain slices. In particular we develop a new metric to determine the conditions under which sparse inhibitory networks form anti-correlated cell assemblies with time-varying activity of individual cells. We find that under these conditions the network displays an input-specific sequence of cell assembly switching, that effectively discriminates similar inputs. Our results support the proposal that GABAergic connections between striatal projection neurons allow stimulus-selective, temporally-extended sequential activation of cell assemblies. Furthermore, we help to show how altered intrastriatal GABAergic signaling may produce aberrant network-level information processing in disorders such as Parkinson’s and Huntington’s diseases.
Highlights
The basal ganglia are critical brain structures for behavioral control, whose organization has been highly conserved during vertebrate evolution [1]
Striatal projection neurons have loose inhibitory interconnections, and here we show that even a highly simplified model of this striatal network is capable of producing slowly-changing activity sequences
The inhibitory postsynaptic potentials (PSPs) are modeled as α-functions characterized by a decay time τα and a peak amplitude APSP
Summary
The basal ganglia are critical brain structures for behavioral control, whose organization has been highly conserved during vertebrate evolution [1]. The great majority (> 90%) of striatal neurons are GABAergic medium spiny neurons (MSNs), which project to other basal ganglia structures and make local collateral connections within striatum [4]. These local connections were proposed in early theories to achieve action selection through strong winner-take-all lateral inhibition [5, 6], but this idea fell out of favor once it became clear that MSN connections are sparse (nearby connection probabilities ’ 10–25% [7, 8]), unidirectional and relatively weak [9, 10]. This proposal is of high potential significance, since sequential dynamics may be central to the striatum’s functional role in the organization and timing of behavioral output [17, 18]
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