Increased dendritic membrane excitability persists in fifteen week atrophic SCA1 Purkinje neurons.

<p><b>(A)</b> Representative dendritic whole-cell patch clamp recordings from a fifteen week old wild-type Purkinje neuron (soma-to-patch distance: 45.0 μm) and fifteen week old ATXN1[82Q] Purkinje neuron (soma-to-patch distance: 48.6 μm). Traces have been aligned at the threshold of the spike. <b>(B)</b> Scatter-plots with single-exponent decay best-fit lines for back-propagating action potential (bAP) amplitude measurements in wild-type and ATXN1[82Q] Purkinje neurons at fifteen weeks of age show less attenuation of bAPs in ATXN1[82Q] mice. Each data point represents a recording from a separate cell. Best-fit line is an exponential decay model with two parameters, of the form <i>y</i> = <i>Ae</i><sup>−<i>bx</i></sup>, consistent with a previous study of action potential backpropagation in Purkinje neurons [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0198040#pone.0198040.ref037" target="_blank">37</a>] and showing R<sup>2</sup> values of 0.9834 (wild-type) and 0.9346 (ATXN1[82Q]). <b>(C)</b> Scatter-plots with single-exponent growth best-fit lines for bAP half-width measurements in wild-type and ATXN1[82Q] Purkinje neurons at fifteen weeks of age show wider bAPs in ATXN1[82Q] mice. Each data point represents a recording from a separate cell. Best-fit line is an exponential growth model with two parameters, of the form <i>y</i> = <i>Ae</i><sup><i>bx</i></sup>. <b>(D)</b> Representative action potential from a somatic whole-cell recording in wild-type and ATXN1[82Q] Purkinje neurons at fifteen weeks of age. The peak-to-trough amplitude of action potentials (summarized in <b>(E)</b>) and the action potential half-width (summarized in <b>(F)</b>) recorded at the soma do not differ significantly between wild-type and ATXN1[82Q] Purkinje neurons at fifteen weeks of age. In <b>(B</b>, <b>C</b>, <b>E</b>, and <b>F)</b> N = 5–10 mice were utilized per genotype. Where error bars are present, data are mean ± SEM. * = <i>P<0</i>.<i>05</i>; NS = Not significant. Statistical significance derived by extra sum of squares F test to determine whether one should reject the null hypothesis that data are best described by a single curve rather than two curves separated by genotype <b>(B</b>, <b>C)</b> or unpaired two-tailed Student’s T-Test <b>(E</b>, <b>F)</b>.</p>