Organization of the anterior limb of the internal capsule in the rat

Veronique Coizet, Sarah R. Heilbronner, Carole Carcenac, Philippe Mailly, Julia F. Lehman, Marc Savasta, Oivier David, Jean Michel Deniau, Henk J. Groenewegen, Suzanne N. Haber

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Dysfunction of the orbitofrontal (OFC) and anterior cingulate (ACC) cortices has been linked with several psychiatric disorders, including obsessive-compulsive disorder, major depressive disorder, posttraumatic stress disorder, and addiction. These conditions are also associated with abnormalities in the anterior limb of the internal capsule, the white matter (WM) bundle carrying ascending and descending fibers from the OFC and ACC. Furthermore, deep-brain stimulation (DBS) for psychiatric disorders targets these fibers. Experiments in rats provide essential information on the mechanisms of normal and abnormal brain anatomy, including WM composition and perturbations. However, whereas descending prefrontal cortex (PFC) fibers in primates form a well defined and topographic anterior limb of the internal capsule, the specific locations and organization of these fibers in rats is unknown. We address this gap by analyzing descending fibers from injections of an anterograde tracer in the rat ACC and OFC. Our results show that the descending PFC fibers in the rat form WM fascicles embedded within the striatum. These bundles are arranged topographically and contain projections, not only to the striatum, but also to the thalamus and brainstem. They can therefore be viewed as the rat homolog of the primate anterior limb of the internal capsule. Furthermore, mapping these projections allows us to identify the fibers likely to be affected by experimental manipulations of the striatum and the anterior limb of the internal capsule. These results are therefore essential for translating abnormalities of human WM and effects of DBS to rodent models.

Original languageEnglish (US)
Pages (from-to)2539-2554
Number of pages16
JournalJournal of Neuroscience
Volume37
Issue number10
DOIs
StatePublished - Mar 8 2017

Bibliographical note

Funding Information:
This work was supported by the National Institutes of Health (Grant P50MH106435 to S.N.H. and Grant F32MH103931 to S.R.H.) and INSERM.

Keywords

  • Cingulate
  • Deep-brain stimulation
  • Homology
  • Orbitofrontal
  • Prefrontal cortex
  • White matter

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