Neuronal pericellular baskets: neurotransmitter convergence and regulation of network excitability

Abstract

A pericellular basket is a presynaptic configuration of numerous axonal boutons outlining a target neuron soma and its proximal dendrites. Recent studies show neurochemical diversity of pericellular baskets and suggest that neurotransmitter usage together with the dense, soma-proximal boutons may permit strong input effects on different timescales. Here we review the development, distribution, neurochemical phenotypes, and possible functions of pericellular baskets. As an example, we highlight pericellular baskets formed by projections of certain Pet1/Fev neurons of the serotonergic raphe nuclei. We propose that pericellular baskets represent convergence sites of competition or facilitation between neurotransmitter systems on downstream circuitry, especially in limbic brain regions, where pericellular baskets are widespread. Study of these baskets may enhance our understanding of monoamine regulation of memory, social behavior, and brain oscillations.

Keywords: Pet1/Fev; VGLUT3; co-transmission; memory; pericellular basket; serotonin.

Figure 1.. Combinations of neurochemically distinct pericellular baskets can target a shared cell soma.

(A) Convergence of TH⁺ and VGLUT3⁺ pericellular baskets has been reported in the lateral septum [2]. (B) 5-HT⁺ and VGLUT3⁺ baskets from separate Pet1 neuron lineages converge on the same targets in the cortex, hippocampus, and septum [14]. (C) Baskets comprised of 5-HT⁺, VGLUT3⁺, and VGLUT3⁺/5-HT⁺ fibers are common in the septum [14]. (D) It remains to be tested whether other combinations of axons known to form pericellular baskets converge on their target neurons.