Abstract
The basal ganglia and pontocerebellar systems regulate somesthetic-guided motor behaviors and receive prominent inputs from sensorimotor cortex. In addition, the claustrum and thalamus are forebrain subcortical structures that have connections with somatosensory and motor cortices. Our previous studies in rats have shown that primary and secondary somatosensory cortex (S1 and S2) send overlapping projections to the neostriatum and pontine nuclei, whereas, overlap of primary motor cortex (M1) and S1 was much weaker. In addition, we have shown that M1, but not S1, projects to the claustrum in rats. The goal of the current study was to compare these rodent projection patterns with connections in cats, a mammalian species that evolved in a separate phylogenetic superorder. Three different anterograde tracers were injected into the physiologically identified forepaw representations of M1, S1, and S2 in cats. Labeled fibers terminated throughout the ipsilateral striatum (caudate and putamen), claustrum, thalamus, and pontine nuclei. Digital reconstructions of tracer labeling allowed us to quantify both the normalized distribution of labeling in each subcortical area from each tracer injection, as well as the amount of tracer overlap. Surprisingly, in contrast to our previous findings in rodents, we observed M1 and S1 projections converging prominently in striatum and pons, whereas, S1 and S2 overlap was much weaker. Furthermore, whereas, rat S1 does not project to claustrum, we confirmed dense claustral inputs from S1 in cats. These findings suggest that the basal ganglia, claustrum, and pontocerebellar systems in rat and cat have evolved distinct patterns of sensorimotor cortical convergence.
Highlights
The cerebral cortex contains numerous modality-specific regions, with each area specialized for a specific type of information processing
Whereas rat S1 does not project to claustrum, we confirmed dense claustral inputs from S1 in cats. These findings suggest that the basal ganglia, claustrum, and pontocerebellar systems in rat and cat have evolved distinct patterns of sensorimotor cortical convergence
We only analyzed cases in which transported tracer labeling was apparent in all subcortical regions of interest: striatum, claustrum, thalamus, and the basal pontine nuclei
Summary
The cerebral cortex contains numerous modality-specific regions, with each area specialized for a specific type of information processing (for review see Krubitzer 2009). Somatosensory and motor cortical areas are thought to process aspects of touch and movement, respectively (Borich et al 2015; Chapin and Lin 1984; Hall and Lindholm 1974; Hoffer et al 2003; Kaas 2004; but see Matyas et al 2010) Information across these two modalities must be integrated in both directions to achieve appropriate somesthetic-guided movements and accurate sensory perceptions of the resulting bodily motion (Arce-McShane et al 2016; Khateb et al 2017; Lee et al 2008, 2013; Murthy and Fetz 1992; PaiVieira et al 2013; Umeda et al 2019, Zagha et al 2013). Our previous work in rodents, for example, has shown that the claustrum receives dense inputs from motor cortex and sends bifurcating projections back to both sensory and motor cortex (Smith and Alloway 2010, 2014; Smith et al 2012)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
