OT and PCX Odor signal∶noise.

<p>(<b>A</b>) Average signal∶noise (s∶n, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034926#s2" target="_blank">Methods</a>) in OT and PCX units. Each point represents average s∶n of each unit, across all odor presentations (>4 trials/unit) and odors. Horizontal bars = average s∶n across units ± SEM. *<i>p</i><0.05, ANOVA followed by Fisher's PLSD.</p

Electrode tip locations verifying extent of OT and PCX recording sites.

<p>Coronal stereotaxic panels showing the approximate location of electrode tips from records used for analysis. Coronal sections span from 2.0 – 0.5 mm anterior of bregma, in 0.5 mm intervals. Panels adapted from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034926#pone.0034926-Paxinos1" target="_blank">[61]</a>.</p

OT and PCX units show odor-specific and sexually-differentiated odor responsivity.

<p>Histogram of OT and PCX odor response data calculated in ‘% responding’ (as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034926#pone-0034926-g004" target="_blank">Fig. 4A</a>), with male and female subjects grouped (<b>A</b>) and sorted by sex (<b>B</b>). Numbers above bars = # units responding.</p

Spontaneous multi-unit activity in the OT and PCX.

<p>(<b>A</b>) Average spontaneous firing rates of OT (left) and PCX units (right). Each point represents average within units of 2 sec prior to odor, across 4–6 trials (<i>n</i> = 30 OT units, 25 PCX units). Horizontal bars = average ± SEM. *<i>p</i><0.05, 2-tailed <i>t</i>-test. (<b>B</b>) Average spontaneous firing rates of males and female units within the OT (left) and PCX units (right). Same data as in (A). Horizontal bars = firing rate average across units ± SEM. n.s. = <i>p</i>>0.05, 2-tailed <i>t</i>-test.</p

Example OT and PCX odor-evoked spike trains and stimulus histograms.

<p>Multiunit activity (MUA) from a single OT (top) and PCX (bottom) recording. Also shown in raster and peristimulus time histogram (PSTH) form is the activity of a single isolated unit (1 unit/region) across each trial of odor presentation. For these purposes, we selected a spontaneously active OT example which is representative of the greater spontaneous firing among OT units versus those found in the PCX (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034926#pone-0034926-g002" target="_blank">Fig. 2</a>). In this example, the PCX unit burst more phasic with respiration, though this is not consistent across all units. Units from both structures in these examples responded to 2 of the 5 odors.</p

Odor-evoked response probability in the OT and PCX.

<p>(<b>A</b>) 3-dimensional histogram of odor selectivity among OT (left) and PCX units (right) in response to the five odorants (male mouse urine, female mouse urine, fox urine, chow, IsoAA; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0034926#s2" target="_blank">Materials and Methods</a>). <i>p</i> value = 2-tailed <i>t</i>-test of spiking 2 sec pre-odor vs. 2 sec during odor (≥4 trials/odor/unit). Units arrangement (#1,2,3, etc.) is based upon average magnitude of significance across odors. Whereas some odors evoked significant responses throughout numerous units (e.g., IsoAA), others (e.g., fox urine) did not. (<b>B</b>) Pie charts of unit tuning in OT and PCX. 0 = not responsive to any odor, 4 = responsive to 4 odors (no unit responded to all 5 odors). 50% of OT and 58% of PCX units displayed a significant modulation in firing rate to at least one odor. Same data as in (A). (<b>C</b>) Pie charts of response magnitudes of odor-evoked activity in OT and PCX. Same data as in (A).</p

Onset of odor input is similar between OT and PCX.

<p>(<b>A</b>) Example traces of unit firing and respiration over the course of 1 sec. Inhalation in respiratory trace is an upward deflection. Hash marks represent unit responses (spikes). t_onset = latency from first inhalation initiation during odor (circle) until the time of the first action potential (depicted here by the green horizontal arrow). (<b>B</b>) Average t_onset values ± SEM within the OT (red) and PCX (blue). (<b>C</b>) Cumulative probability plot of t_onset values (same data as in (B)). Dashed lines = normal fits of OT (red) and PCX (blue) cumulative probability data.</p

Temporal dynamics of odor-evoked activity in OT and PCX neural ensembles.

<p>(<b>A</b>) 3-dimensional histograms of average firing frequency for each unit across the five odors within the OT (top) and the PCX (bottom). Diversity of intensity in spontaneous firing and odor-evoked changes in firing are visible within both structures. Units arrangement (#1,2,3, etc.) is arbitrary but consistent across panels within regions. (<b>B</b>) Average firing frequency of OT (top) and PCX (bottom) units relative to odor onset sorted by odors. (<b>C</b>) Raw (top) and normalized (bottom) average firing frequency of OT and PCX units sorted by odors (left to right). (<b>D</b>) Average firing frequency across all odors and units. Data displayed as mean ± SEM. Vertical magenta dashed line = odor onset.</p