Different Brain Cells Use Different Strategies to Communicate with Movement Control Centers
Background: The cerebral cortex communicates with the striatum through two major classes of layer 5 pyramidal neurons: intratelencephalic-type (IT-type) and pyramidal tract-type (PT-type). While both contribute to topographically organized corticostriatal circuits, how their projection patterns differ across cortical areas remains unclear. Clarifying these differences is essential to understanding how sensory and motor information are integrated in the basal ganglia.
Hypothesis: This study hypothesized that IT-type and PT-type cortical neurons exhibit distinct corticostriatal projection patterns, with IT-type neurons showing greater topographic precision and stereotypy than PT-type neurons, and that these differences vary across sensory, motor and frontal cortical areas.
Methods: The authors used Cre-driver mice specific for IT-type (Tlx3_PL56) and PT-type (Sim1_KJ18) neurons. Cre-dependent viral tracers expressing fluorescent reporters were injected into sensory, motor and frontal cortices. Brain sections were imaged and analyzed in three dimensions using Neurolucida for neuronal annotation and the BrainMaker module of NeuroInfo for whole-brain alignment to the CCF v3, enabling voxel-based quantification of corticostriatal projections.
Results: IT-type neurons projected bilaterally to cortex and striatum, while PT-type neurons projected ipsilaterally and to subcortical structures. IT-type projections displayed higher inter-animal consistency and greater overlap between interconnected cortical regions. PT-type projections were more focal, less stereotyped and exhibited reduced correlation across animals. Striatal clusters received distinct sensory and motor inputs organized along the anterior–posterior axis.
Conclusions: This study concluded that corticostriatal topography differs by cortical area and cell type. IT-type neurons provide broad, consistent mapping across interconnected cortical networks, whereas PT-type neurons convey more localized and variable projections, reflecting distinct roles in striatal information processing.
Hooks BM, Papale AE, Paletzki RF, Feroze MW, Eastwood BS, Couey JJ, Winnubst J, Chandrashekar J, Gerfen CR. Topographic precision in sensory and motor corticostriatal projections varies across cell type and cortical area. Nat Commun 2018;9(1):3549. doi: 10.1038/s41467-018-05780-7.
