New publication: Perineuronal nets stabilize the grid cell network
A reliable sense of space is essential for daily life and memory formation. Breaking down the extracellular matrix around grid cells makes the mental map unstable [Nature Communications 11th of January, 2021].
Perineuronal nets (green) surrounding ntorhinal PV+ neuron (red) in entorhinal cortex.
The grid cells of medial entorhinal cortex forms a reference frame for mapping physical space, but it is still unclear how grid cells achieve their extraordinary stable
activity patterns across time and environments. In sensory cortices, a specialized form of
extracellular matrix (perineuronal nets, PNNs) has been shown to stabilize synapses and reduce plasticity, but the role of PNNs in spatial coding remained unknown.
In the current study we removed PNNs in entorhinal cortex of adult rats and found a dramatically impaired grid cell coding of a novel environment. Surprisingly, when we returned the rats to familiar arenas, the stored grid cell maps had become unstable.
Furthermore we show that both the temporal and spatial organization of firing is disturbed after PNN removal. This is remarkable as the temporal organization of grid cells is preserved between behaviour and sleep (Gardner et al.; Trettel et al., 2019) and even when the grid pattern is lost after hippocampal inactivation (Bonnevie et al., 2013; Almog et al., 2019, bioRxiv doi.org/10.1101/592006).
Christensen AC, Lensjø KK, Lepperød ME, Dargly SA, Sutterud H, Blackstad JS, Fyhn M, Hafting T. Perineuronal nets stabilize the grid cell network. Nature Communications 12: 253 (2021). https://doi.org/10.1038/s41467-020-20241-w