Comparisons of fitted time series obtained from the GLM for ROIs in awake dogs.

<p>The ROIs are in brain regions that were activated by low and high odor concentration, as well as parametric modulation by odor intensity in awake dogs. These regions are olfactory bulb and cerebellum, which are shown in bold face in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t003" target="_blank">Tables 3</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t004" target="_blank">4</a>, and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t006" target="_blank">6</a>. In each of these regions, the ROI was determined by a sphere which centers at the peak activation of parametric modulation and has a radius of 2 mm. Fitted time series for low concentration are shown in blue, and high concentration in red.</p

Group activation maps for awake dogs.

<p>(Overall FDR = 0.05, cluster threshold  = 15 voxels using AlphaSim, t-contrast) Three orthogonal views are shown for each subfigure. Hot colormap is used for activation intensity, and important areas are indicated by arrows with labels. Subfigure (A) corresponds to low concentration odorant (0.016 mM), subfigure (B) corresponds to high concentration odorant (0.16 mM). The activation in olfactory bulb for low concentration is not visible in this view, please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t003" target="_blank">Table 3</a> for activation statistics with regard to this region. (A: Anterior, P: posterior, S: superior, I: inferior, L: left, R: right)</p

Group activation maps for parametric modulation in anesthetized dogs (A) and awake dogs (B).

<p>(Overall FDR = 0.05, cluster threshold  = 15 voxels using AlphaSim, t-contrast). Three orthogonal views are shown for each subfigure. Hot colormap is used for activation intensity, and important areas are indicated by arrows with labels. (A: Anterior, P: posterior, S: superior, I: inferior, L: left, R: right)</p

Odorant applicator sequences controlled by VT-8 Warner Timer software and fMRI experimental block design.

<p>For the first sequence, green arrows indicate the onset time of the odorant stimulus and red arrows indicate when the stimulation ends. For the second one, green arrows indicate the onset of clearance of odorant, and red arrows indicate when it ends. The third sequence shows the fMRI block design in this work, matching the first sequence. “0” and “1” denote the odor “on” and “off” conditions.</p

A schematic of the olfactory pathway in canines.

<p>Arrows indicate the olfactory signal flow. Anterior olfactory cortex, piriform cortex, periamygdaloid cortex, and entorhinal cortex are contained in a green box and the green arrows extending from this green box indicate the olfactory signal from them go to frontal cortex and thalamus. The gray arrow from entorhinal cortex to hippocampal formation indicates the olfactory signal to hippocampus comes only from the entorhinal cortex. For functions of each site, please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone.0086362-Jensen1" target="_blank">[1]</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone.0086362-Zald1" target="_blank">[4]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone.0086362-Ramnani1" target="_blank">[6]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone.0086362-Zobel1" target="_blank">[7]</a>.</p

Comparison of activation maps with and without camera motion tracking parameters as regressors.

<p>(Overall FDR = 0.05, cluster threshold  = 15 voxels using AlphaSim, t-contrast) The activtion maps were for low concentration (0.016 mM) in awake dogs. The activation map obtained with only SPM realignment parameters as regressors is shown in cool colormap. The activation map with camera motion tracking parameters and SPM realignment parameters as regressors is shown in hot colormap. The common areas are overlaid such that they appear as purple. We found 3 clusters, 379 voxels in cool-colored map (same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t003" target="_blank">Table 3</a>); 3 clusters, 396 voxels in hot-colorred map, and 3 clusters, 340 voxels in the common area. (A: Anterior, P: posterior, S: superior, I: inferior, L: left, R: right)</p

The interlinked trigger system.

<p>Arrows denote the triggering direction. A laptop with VT-8 software <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone.0086362-Warner1" target="_blank">[35]</a> provided the interface to trigger the odorant applicator. The VT-8 software is a platform that can be used to design and display sequence of odorant flow and clearance, and provides communication and control to odorant applicator to generate the expected experimental sequence. Once the odorant applicator started to give odorant stimulus, it sent a signal to the trigger synchronizer, which then triggered the scanner and sent a signal to the manual trigger. The manual trigger, as the name suggests, was manually set for switching between two states. One was waiting for signals from trigger synchronizer, and the other was waiting for signal from a hand-pressed button. In our experiment, the first state was used for data collection and the second was used only for testing. Upon receiving the signal, it triggered the infrared radiation transmitter to give off infrared rays, and the infrared camera to start recording infrared reflections from the dog's head, and the motion parameter recording palmtop to start calculating displacement parameters. When the camera was triggered, it sent the signal to the monitor for display.</p

A black dog positioned with muzzle in mask for odorant delivery.

<p>The dot reflector is mounted to dog's head for motion tracking, the knee coil encompasses the dog's head and the mask is mounted on the front frame of the knee coil.</p

Flow chart of proposed spatial normalization procedure.

<p>A good quality anatomical image of an anesthetized dog was chosen as the template from Session 4 (4, being just an example). Then one functional image from the same session (Session 4) was chosen and normalized to the template. Subsequently, this transformed functional image was used as a template to normalize other functional images of other sessions. (*Anes:Anesthetized)</p

Cluster-level statistics of activations for anesthetized dogs, low concentration of odorant.^*

<p>*: ROIs shown in bold face were commonly activated for low and high (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t002" target="_blank">Table 2</a>) odor concentration, as well as parametric modulation by odor concentration (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t005" target="_blank">Table 5</a>).</p