28 research outputs found
Identification of cholinergic and non-cholinergic neurons in nucleus basalis.
<p>(<b>A</b>) Examples of retrospective streptavidin (green) and anti-ChAT (red) fluorescence for two recorded neurons. In one recording the streptavidin-positive soma co-labels with anti-ChAT. Anti-ChAT fails to label the other neuron, although nearby cells are ChAT<sup>+</sup>, indicating that the anti-ChAT staining was successful in this slice. (<b>B</b>) Summary schematic showing the locations of nucleus basalis and of all recordings. Red and blue markers indicate the somatic locations of recordings from ChAT<sup>+</sup> and ChAT<sup>β</sup> neurons, respectively. Grey shading indicates the probability distribution for nucleus basalis (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011046#s2" target="_blank">Methods</a> section and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011046#pone-0011046-g001" target="_blank">figure 1</a>).</p
Location and dimensions of nucleus basalis.
<p>(<b>A</b>) Widefield image of anti-ChAT immunofluorescence of a coronal section, approximately 1mm posterior to bregma, with prominent anti-ChAT staining in nucleus basalis and caudate putamen. (<b>B</b>) A sub-region of the section in A, showing ChAT-immunoreactive somata in nucleus basalis. (<b>C</b>) Illustration of the method used to describe the location of nucleus basalis. To pool the locations of nucleus basalis from multiple animals, for each section we first overlaid the anti-ChAT image onto a brightfield image of a representative coronal section (panel 1). This aligned all anti-ChAT images to the common brightfield image. For each section we manually drew an outline around all ChAT<sup>+</sup> somata in nucleus basalis (panel 2) and converted this outline to a binary mask (panel 3). These masks were averaged to give a probability density distribution for nucleus basalis (panel 4). (<b>D</b>) The probability density distribution was then aligned with a schematic of the coronal slice for display purposes. To calculate the dimensions of nucleus basalis we measured the probability density along major and minor axes of the approximately elliptical probability density distribution (dashed lines). (<b>E</b>) A threshold of 10% of the peak intensity (dashed line) in each axis gave dimensions for nucleus basalis of 2.52 mm in the ventromedial-dorsolateral (major) axis and 1.12 mm in the dorsomedial-ventrolateral (minor) axis.</p
Comparison of action potential waveforms.
<p>(<b>A</b>) Example action potentials from a ChAT<sup>+</sup> (black) and a ChAT<sup>β</sup> (grey) neuron, illustrating the difference in spike waveform. Spikes are aligned to threshold (filled arrowhead). The ChAT<sup>+</sup> neuron has a broader action potential with a shoulder on the decaying phase (open arrowhead). (<b>B</b>) The shoulder (open arrowhead) is clearly visible in the phase plot for ChAT<sup>+</sup> action potential: the shoulder reduces the maximum rate of decay of the action potential. (<b>C</b>) Threshold, amplitude, half width and decay time for action potentials in ChAT<sup>+</sup> (black) and ChAT<sup>β</sup> (grey) neurons. nβ=β9 ChAT<sup>+</sup> and 30 ChAT<sup>β</sup> neurons.</p
Examples of whole-cell recordings and subthreshold characteristics.
<p>(<b>A and B</b>) Maximum intensity projections of 2-photon image stacks acquired during recording from two neurons, one ChAT<sup>+</sup> (A) and one ChAT<sup>β</sup> (B). In each, the recording pipette is visible to the right of the soma. (<b>C and D</b>) Voltage responses to β200, β150, β100, β50, 0, 50 and +200 pA current steps for 300ms. Dashed lines indicate 0 mV. C is from the ChAT<sup>+</sup> neuron in A; D from the ChAT<sup>β</sup> neuron in B. (<b>E</b>) Voltage-current curves for the ChAT<sup>+</sup> (black, filled symbols) and ChAT<sup>β</sup> (open, grey symbols) neurons in A and B, both showing anomalous rectification at potentials hyperpolarized to rest. (<b>F</b>) Sag ratio (steady state / peak voltage) during 300 ms, β200 pA current steps in ChAT<sup>+</sup> and ChAT<sup>β</sup> neurons.</p
Cell-attached recordings and spontaneous firing activity.
<p>(<b>A</b>) Schematic illustration of a coronal slice approximately 1mm posterior to bregma, based on the atlas of Franklin and Paxinos (2008) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011046#pone.0011046-Sim1" target="_blank">[25]</a>. (<b>B</b>) Brightfield image of a slice showing the region around nucleus basalis during recording from a neuron in nucleus basalis. Arrowheads mark the recording pipette. (<b>C</b>) Example of a cell-attached recording from a neuron which did not exhibit spontaneous activity. Current injection (500 pA, 300 ms) evoked action potentials. Inset: action potential waveform. (<b>D</b>) Raster plots showing 10 seconds of irregular firing in 12 spontaneously firing neurons recorded in the cell-attached configuration. Each vertical line denotes the timing of an action potential and neurons are arranged in two columns, each containing the plots for 6 neurons. (<b>E</b>) Raster plots from two spontaneously firing neurons in the whole-cell configuration. The neurons were identified as ChAT+ (red) and ChATβ (blue) neurons by retrospective immunocytochemistry.</p
Electrophysiology of ChAT<sup>+</sup> and ChAT<sup>β</sup> magnocellular neurons in adult mouse nucleus basalis.
<p>Electrophysiology of ChAT<sup>+</sup> and ChAT<sup>β</sup> magnocellular neurons in adult mouse nucleus basalis.</p
Comparison of firing rates and after-spike potentials.
<p>(<b>A</b>) Spike frequency as a function of injected current for ChAT<sup>+</sup> (black symbols) and ChAT<sup>β</sup> neurons (grey symbols). The shaded areas denote the full range of each population (nβ=β9 ChAT<sup>+</sup> and 28 ChAT<sup>β</sup> neurons). Inset: Spike amplitudes during trials with only three action potentials. ChAT<sup>+</sup> (black symbols) and ChAT<sup>β</sup> neurons (grey symbols) displayed weak spike amplitude accommodation. (<b>B</b>) Example action potentials from a ChAT<sup>+</sup> (black) and a ChAT<sup>β</sup> (grey) neuron, illustrating the differences in after-spike potentials. Traces were aligned to the threshold (arrowhead). Inset: Same action potentials on an expanded time scale, clearly showing the fAHP and, in the ChAT<sup>β</sup> neuron, the ADP. (<b>C</b>) Plots showing the amplitudes of fAHP, ADP and sAHP for ChAT<sup>+</sup> (black) and ChAT<sup>β</sup> (grey) neurons. nβ=β9 ChAT<sup>+</sup> and 30 ChAT<sup>β</sup> neurons.</p
Hyperpolarization of cholinergic neurons from ChAT-Cre/Ai35(Arch-GFP) mice.
<p><b>(A)</b> Whole-cell recordings from Arch-GFP-labeled neurons in nucleus basalis in acute slices from Arch-ChR2 mice, illustrating the effects of 300 ms white illumination (bar) at intensities of 1.2, 1.7, 2.2 and 3.7 mW/mm<sup>2</sup>. Dashed horizontal lines denote 0 mV. Resting membrane potentials -51, -51, -52 and -52 mV. <b>(B)</b> Steady-state hyperpolarization and membrane time constant during white illumination from the recording illustrated in panel A. Arrowheads indicate example traces in panel A. <b>(C and D)</b> Inhibition of spiking by white illumination. Spiking was evoked by DC (C) or 2Hz (D) current injection to depolarize cell beyond spike threshold. Spikes were eliminated by 7 mW/mm<sup>2</sup> white illumination (bar) for 1 second (C) or for 20 ms (D). Initial membrane potential (during DC current injection) was -33 mV in panel C and resting membrane potential was -49 mV in panel D.</p
Membrane properties of cholinergic neurons.
<p>Membrane properties of cholinergic neurons.</p