Biology subjects

King, B. R.

Publications and source records attributed to King, B. R..

2 recordsLinked to original sources

bioRxiv2020

Hippocampal and striatal responses during motor learning are modulated byprefrontal cortex stimulation

While it is widely accepted that motor sequence learning (MSL) is supported by a prefrontal-mediated interaction between hippocampal and striatal networks, it remains unknown whether the functional responses of these networks can be modulated in humans with targeted experimental interventions. The present proof- of-concept study employed a comprehensive multimodal neuroimaging approach, including functional magnetic resonance (MR) imaging and MR spectroscopy, to investigate whether individually-tailored theta-burst stimulation of the dorsolateral prefrontal cortex can modulate responses in the hippocampus and striatum during motor learning. Our results indicate that stimulation influenced task-related connectivity patterns within hippocampo-frontal and striatal networks. Stimulation also altered the relationship between the levels of gamma-aminobutyric acid (GABA) in the stimulated prefrontal cortex and learning-related changes in both activity and connectivity in fronto-striato-hippocampal networks. This study provides the first experimental evidence that brain stimulation can alter motor learning-related functional responses in the striatum and hippocampus.

neuroscience↗

bioRxiv2020

XMAP215 and γ-tubulin additively promote microtubule nucleation in purified solutions

Microtubule nucleation is spatiotemporally regulated in cells by several molecules, including the template {gamma}-tubulin and the polymerase XMAP215. Recently, XMAP215 and the {gamma}-tubulin ring complex were reported to function synergistically, and this synergy was hypothesized to be due to direct binding between XMAP215 and {gamma}-tubulin. Here, we address this hypothesis by 1) probing domain requirements for XMAP215 to promote microtubule nucleation and 2) testing whether XMAP215 functions synergistically with {gamma}-tubulin in the absence of the other ring complex proteins. We confirm that {gamma}-tubulin and XMAP215 are classically defined nucleators that reduce the nucleation lag seen in bulk tubulin assembly. Then, using deletion constructs, we show that XMAP215s ability to nucleate microtubules in purified solutions correlates with its ability to elongate existing microtubules and does not depend on the number of TOG domains. Finally, we show that XMAP215 and {gamma}-tubulin promote {beta}-tubulin assembly in an additive, not synergistic, manner. Thus, their modes of action during microtubule nucleation are distinct, and the synergy reported between XMAP215 and the {gamma}-tubulin ring complex is not due to {gamma}-tubulin alone.

biochemistry↗