Cerebellum (2012) 11:246–258 lurcher mutants with regard to cell density [27]. Future experiments should provide a more detailed picture of the total number of neurons per cell type per CN. Behavioral Effects of Widespread Purkinje Cell Loss The abnormal motor behavior in both young and old PCα1KO mice was dominated by ataxic movements. Since the behav- ioral abnormalities were already visible before the degeneration occurred (i.e. in young P18 and P30 PCα1KO mice), this indicates that the lack of functional CaV2.1 channels in Purkinje cells can induce the same behavioral aberrations as an absence of Purkinje cells (i.e. in old P200–250 PCα1KO mice). The severity of the ataxic symptoms in PCα1KO mice was also reflected by the fact that, unlike the WT controls, the mutants did not show an increase in their performance on the rotarod over time. Whether there is cerebellar motor learning deficit in the PCα1KO mice could not be assessed since motor learning (i.e. showing improved performance on the rod over time) may have been obscured by the severity of the ataxic phenotype. The severe effect on motor coordination in PCα1KO mice is likely to be due to the disrupted Purkinje cell output and the subsequent deregulation of activity pat- terns downstream [18, 42], which might be relatively normal, at least initially, as was described for lurcher mice [43]. Summary This report represents a cell type-specific ablation of CaV2.1 channels leading to a disease phenotype. We demonstrate that specific ablation of these channels in Purkinje cells is sufficient to cause cerebellar ataxia that precedes progressive Purkinje cell loss. Conditional Cacna1a mice appear espe- cially useful for dissecting the cell-specific role of CaV2.1 channels in neuronal circuitries such as in the cerebellum and in revealing the mechanisms underlying human disease. Acknowledgments The authors are grateful to E. Galliano for constructive discussion and help with the rotarod experiments and T.J.H. Ruigrok for the excellent assistance with the quantification of the histological data. This work was supported by a grant from the Centre for Medical Systems Biology within the framework of the Netherlands Genomics Initiative/Netherlands Organisation for Scientific Research (NWO; A.v.d.M.), Erasmus Fellowship (F.E.H.), NWO-ALW (F.E.H., C.D.Z.), NWO-ZON-MW (F.E.H., C.D.Z.), Neuro- BSIK (C.D.Z.), Prinses Beatrix fonds (C.D.Z.), and National Institutes of Health R01 NS33592 (E.J.H.). Conflicts of interest The authors declare that there are no potential conflicts. Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which per- mits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. 257 References 1. Mintz IM, Adams ME, Bean BP. P-type calcium channels in rat central and peripheral neurons. Neuron. 1999;9:85–95. 2. Westenbroek RE, Sakurai T, Elliott EM, Hell JW, Starr TV, Snutch TP, et al. Immunochemical identification and subcellular distribu- tion of the alpha 1A subunits of brain calcium channels. J Neurosci. 1995;15:6403–18. 3. Kulik A, Nakadate K, Hagiwara A, Fukazawa Y, Luján R, Saito H, et al. Immunocytochemical localization of the alpha 1A subunit of the P/Q-type calcium channel in the rat cerebellum. Eur J Neurosci. 2004;19:2169–78. 4. Jun K, Piedras-Renteria ES, Smith SM, Wheeler DB, Lee SB, Lee TG, et al. Ablation of P/Q-type Ca(2+) channel currents, altered synaptic transmission, and progressive ataxia in mice lacking the alpha(1A)-subunit. Proc Natl Acad Sci USA. 1999;96:15245–50. 5. Fletcher CF, Tottene A, Lennon VA, Wilson SM, Dubel SJ, Paylor R, et al. Dystonia and cerebellar atrophy in Cacna1a mice lacking P/Q calcium channel activity. FASEB J. 2001;15:1288–90. 6. Kaja S, van de Ven RC, Broos LA, Frants RR, Ferrari MD, van den Maagdenberg AM, et al. Characterization of acetylcholine release and the compensatory contribution of non-Ca(v)2.1 channels at motor nerve terminals of leaner Ca(v)2.1-mutant mice. Neuroscience. 2007;144:1278–87. 7. Katoh A, Jindal JA, Raymond JL. Motor deficits in homozygous and heterozygous P/Q-type calcium channel mutants. J Neuro- physiol. 2007;97:1280–7. 8. Herrup K, Wilczynski SL. Cerebellar cell degeneration in the leaner mutant mouse. Neuroscience. 1982;7:2185–96. 9. Rhyu IJ, Oda S, Uhm CS, Kim H, Suh YS, Abbott LC. Morphologic investigation of rolling mouse Nagoya (tg(rol)/tg (rol)) cerebellar Purkinje cells: an ataxic mutant, revisited. Neurosci Lett. 1999;266:49–52. 10. Sawada K, Kalam Azad A, Sakata-Haga H, Lee NS, Jeong YG, Fukui Y. Striking pattern of Purkinje cell loss in cerebellum of an ataxic mutant mouse, tottering. Acta Neurobiol Exp. 2009;69:138–45. 11. Zwingman TA, Neumann PE, Noebels JL, Herrup K. Rocker is a new variant of the voltage-dependent calcium channel gene Cacna1a. J Neurosci. 2001;21:1169–78. 12. Hoebeek FE, Stahl JS, van Alphen AM, Schonewille M, Luo C, Rutteman M, et al. Increased noise level of Purkinje cell activities minimizes impact of their modulation during sensorimotor control. Neuron. 2005;45:953–65. 13. Walter JT, Alviña K, Womack MD, Chevez C, Khodakhah K. Decreases in the precision of Purkinje cell pacemaking cause cerebellar dysfunction and ataxia. Nat Neurosci. 2006;9:389–97. 14. Zhou YD, Turner TJ, Dunlap K. Enhanced G protein-dependent modulation of excitatory synaptic transmission in the cerebellum of the Ca2+ channel-mutant mouse, tottering. J Physiol. 2003;547:497–507. 15. Matsushita K, Wakamori M, Rhyu IJ, Arii T, Oda S, Mori Y, et al. Bidirectional alterations in cerebellar synaptic transmission of tottering and rolling Ca2+ channel mutant mice. J Neurosci. 2002;22:4388–98. 16. Chen G, Popa LS, Wang X, Gao W, Barnes J, Hendrix CM, et al. Low-frequency oscillations in the cerebellar cortex of the tottering mouse. J Neurophysiol. 2009;101:234–45. 17. Campbell DB, North JB, Hess EJ. Tottering mouse motor dysfunction is abolished on the Purkinje cell degeneration (pcd) mutant background. Exp Neurol. 1999;160:268–78. 18. Hoebeek FE, Khosrovani S, Witter L, De Zeeuw CI. Purkinje cell input to cerebellar nuclei in tottering: ultrastructure and physiol- ogy. Cerebellum. 2008;7:547–58.