Wavelet analysis of arterial pressure and <i>SV</i> recordings.

<p>Analysis of (a,b) arterial blood pressure and (c,d) <i>SV</i> of a single retinal vessel of a representative rat. Left panels: Color-coded wavelet energy over frequencies and time. Three time intervals are selected according to the experimental protocol: control, U-46619, and SNAP. Right panels: Wavelet energy spectra. Different colors code different time intervals as the legend describes. The peak at 0.5 Hz corresponds to Mayer waves, 1 Hz corresponds to ventilation frequency and 6.4 Hz corresponds to the pulse. <i>SV</i> analysis reveals the same frequencies although shape of the peaks and response to drug infusion are different.</p

Schematic presentation.

<p>The experimental set up (left panel) and the experimental protocol (right panel). Experimental setup includes endoscope (1), laser module (2), and CMOS camera (3). The rat was anesthetized and paralyzed. Experimental protocol includes I.V. infusion of U-46619 and SNAP.</p

Wavelet analysis of <i>SV</i> recordings.

<p>Response of two vessels in the same representative rat. Left panels: Color-coded wavelet energy over frequencies and time. Right panels: Wavelet energy spectra where different colors correspond to control (red), U-46619 administration (green) and SNAP administration (blue) periods. Note that vessels in the same network may respond differently: (a,b) One vessel demonstrates vasomotion activity at the frequency of about 0.17 Hz in response to infusion of U-46619 and no Mayer wave activity is observed. (c,d) The other vessel demonstrates a weaker response to U-46619 at about 0.15 Hz but shows Mayer wave activity at 0.5 Hz in response to SNAP administration.</p

Change of <i>SV</i> dynamics in response to drug infusion.

<p>“Exp” denotes experiment (animal) number. <i>N</i> is the number of vessels segmented from individual experiments. <i>m</i> is the number of vessels for which spontaneous oscillatory activity (at least 10% above the noise background) was detected. <i>E</i> is the wavelet energy of the most prominent peak in the response relative to the wavelet energy at the same frequency in the control (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0173805#pone.0173805.e004" target="_blank">Eq 3</a>). <i>f</i> is the most prominent frequency in the corresponding frequency band. Energies and frequencies correspond to the vessels with induced vasomotion, i.e. to <i>n</i>₁ and <i>n</i>₂ vessels. Indexes 1 and 2 denote frequency bands of 0.1–0.3 Hz and 0.3–0.7 Hz, respectively. <i>n</i> is the number of vessels for which prominence of the highest peak (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0173805#pone.0173805.e005" target="_blank">Eq 4</a>) in the response is at least 10% higher than in the control.</p

Distribution of number of vessels with increased activity.

<p>The ratio of number of vessels <i>n</i>_1,2 with increased activity in response to drug administration to the total number of vessels <i>N</i> allocated in an individual experiment. The activity is estimated in two frequency bands: 0.1–0.3 Hz (dark blue and dark orange) and 0.3–0.7 Hz (light blue and light orange).</p

Organized spatial phase dynamics.

<p>(A) Phase maps for a short time interval (the same preparation as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105879#pone-0105879-g004" target="_blank">Figure 4</a>), every 4th frame is shown. Wrapped phase is color-coded from to . Each row of 10 frames roughly corresponds to one period of TGF oscillation. Maps in each column tend to reproduce their phase pattern for 4 periods. (B) First four empirical spatial eigenmodes (PC1–PC4) for the time period from 900 to 1100 seconds and the corresponding paired phase plots, displaying how coefficients for the pairs of modes change with time in relation to another mode. Clear oscillatory behaviour is seen for the first two eigenmodes, which correspond to concentric phase wave-like pattern. (inset) Cumulative fraction of variance explained by the first 20 modes; first two modes capture around 45% of the variation in the data. (C) Dynamics of the fraction of variance explained by the first 4 modes in moving 250 s-wide time windows for the 6 experiments shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105879#pone-0105879-g002" target="_blank">Figure 2</a>. (D) boxplots that summarize the values shown in (C), phase delays are highly spatially organized over the whole experiment.</p

Schematic presentation of characteristics used for spectral analysis.

<p>Blue curve is the response (U-46619 or SNAP) wavelet spectrum, green curve is the control spectrum. <i>f</i>_<i>r</i> and <i>f</i>_<i>c</i> are the frequencies of the most prominent peaks in the response and control spectra, respectively. <i>E</i>_<i>r</i>(<i>f</i>_<i>r</i>) and <i>E</i>_<i>c</i>(<i>f</i>_<i>r</i>) are the energy values in the response and control spectra, respectively. <i>E</i>_<i>rb</i> is the energy value of the noise background in the response spectrum at <i>f</i>_<i>r</i>, and <i>E</i>_<i>cb</i> is the energy value of the noise background in the control spectrum at <i>f</i>_<i>c</i>.</p

Image segmentation.

<p>A representative example of image segmentation. a) Mean SV frame. Red polygons mark regions for vessel segmentation. b) Vessel <i>SV</i> profile as a function of time. Values at each moment of time are calculated as averaged values along scan lines perpendicular to the vessel axis over the selected region. The center line (dashed) always belongs to the individual vessel (high <i>SV</i> values).</p

Local coherence maps for the preparations shown in Figure 2.

<p>Areas of highly locally coherent dynamics can be seen in all preparations, even in the one where only small fraction of the kidney surface showed significant TGF peak in Fourier spectrum. White square in the lower left corner show the span of the neighborhood area.</p

Heart position with respect to the objective and laser light.

<p>An isolated heart is attached to the perfusion system through an aortic cannula for retrograde perfusion. Excitation and registration of the Raman scattering is done through the objective.</p