A single-neuron tracing study of arkypallidal and prototypic neurons in healthy rats
- 626 Downloads
The external globus pallidus (GP) is known as a relay nucleus of the indirect pathway of the basal ganglia. Recent studies in dopamine-depleted and healthy rats indicate that the GP comprises two main types of pallidofugal neurons: the so-called “prototypic” and “arkypallidal” neurons. However, the reconstruction of complete arkypallidal neurons in healthy rats has not been reported. Here we visualized the entire axonal arborization of four single arkypallidal neurons and six single prototypic neurons in rat brain using labeling with a viral vector expressing membrane-targeted green fluorescent protein and examined the distribution of axon boutons in the target nuclei. Results revealed that not only the arkypallidal neurons but nearly all of the prototypic neurons projected to the striatum with numerous axon varicosities. Thus, the striatum is a major target nucleus for pallidal neurons. Arkypallidal and prototypic GP neurons located in the calbindin-positive and calbindin-negative regions mainly projected to the corresponding positive and negative regions in the striatum. Because the GP and striatum calbindin staining patterns reflect the topographic organization of the striatopallidal projection, the striatal neurons in the sensorimotor and associative regions constitute the reciprocal connection with the GP neurons in the corresponding regions.
KeywordsBasal ganglia Single neuron tracing Globus pallidus Striatum Arkypallidal neuron Prototypic neuron
We are deeply grateful to Prof. Paul Bolam for his sincere encouragement and critical reading of the manuscript. This study was supported by Grants-in-Aid from The Ministry of Education, Culture, Sports, Science, and Technology (MEXT) for Scientific Research (25282247, 15K12770); and for Scientific Researches on Innovative Areas “Prediction and Decision Making” (26120725) and “Adaptive Circuit Shift” (26112001).
Compliance with ethical standards
Conflict of interest
The authors declare no competing financial interest.
- Abdi A, Mallet N, Mohamed FY, Sharott A, Dodson PD, Nakamura KC, Suri S, Avery SV, Larvin JT, Garas FN, Garas SN, Vinciati F, Morin S, Bezard E, Baufreton J, Magill PJ (2015) Prototypic and arkypallidal neurons in the dopamine-intact external globus pallidus. J Neurosci 35:6667–6688CrossRefPubMedPubMedCentralGoogle Scholar
- Dodson PD, Larvin JT, Duffell JM, Garas FN, Doig NM, Kessaris N, Duguid IC, Bogacz R, Butt SJB, Magill PJ (2015) Distinct developmental origins manifest in the specialized encoding of movement by adult neurons of the external globus pallidus. Neuron 86:501–513CrossRefPubMedPubMedCentralGoogle Scholar
- Ohno S, Kuramoto E, Furuta T, Hioki H, Tanaka YR, Fujiyama F, Sonomura T, Uemura M, Sugiyama K, Kaneko T (2012) A morphological analysis of thalamocortical axon fibers of rat posterior thalamic nuclei: a single neuron tracing study with viral vectors. Cereb Cortex 22:2840–2857CrossRefPubMedGoogle Scholar