Accuracy of vocalization discrimination based on the spike activities of an ensemble of neurons in AAF and PAF.

<p>The results of 3, 5, 10, 25 and 50 randomly selected neurons are plotted as a function of the bin size in different panels. Circles (AAF) and triangles (PAF) are the mean values of 50 neuron selections and the dots represent the SD. To facilitate comparison, the functions of PAF are shifted slightly to the right. Asterisk indicates that the difference of mean values between AAF and PAF neurons is statistically significant (p<0.05, t-test).</p

Responses to the fifteen different stimuli by a representative AAF neuron.

<p>In each panel, the top shows the sonogram of the stimulus with the y-axis denoting the frequency from 0 Hz (bottom) to 5 kHz (top) on a linear scale. Time is on the x-axis, and the gray scale displays the energy of the stimulus, with darker colors indicating greater power. Below the sonograms are the spike rasters. Each line is a different trial (bottom line is the first trial of that stimulus type) and each dot mark represents a single spike. Below this is the post-stimulus time histogram (PSTH). Bin size is 1 ms, smoothed by with a Gaussian kernel (σ = 10). A–E show forward meows, F–H are time-reversed meows, K–O are human vowels. This neuron shows similar temporal patterns of response to all the stimuli.</p

Stimulus information transmitted by AAF and PAF neurons.

<p>A and B: transmitted information as a function of the temporal precision (1/q) of the example AAF and PAF neurons shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052942#pone-0052942-g001" target="_blank">Figs 1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052942#pone-0052942-g002" target="_blank">2</a>. Filled symbols represent the value of information is significantly higher than the chance level (H_shuffled +2SD). C and D: scatters of the highest value of information (H_max) versus the information obtained when only the firing rate is considered (H_count at q = 0) in AAF and PAF neurons. Diagonal line corresponds to H_count = H_max.</p

Individual PSTHs of 102 PAF neurons.

<p>Conventions as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0052942#pone-0052942-g003" target="_blank">Fig. 3</a>.</p

Comparison of the mean PSTHs averaged across all AAF and PAF neurons.

<p>Black and white curves represent the mean PSTHs of AAF and PAF, respectively. Shaded area represents SE. Vertical dashed lines indicate the onset and offset of stimulus, respectively.</p

Comparison of response properties of AAF and PAF neurons.

<p>A: mean of excitatory response duration averaged over 102 PAF neurons against those of 92 AAF neurons. Each symbol represents the mean value of one stimulus. Filled symbol indicates that the difference of mean values between AAF and PAF neurons is statistically significant (p<0.05, t-test). Open symbol indicates that the difference is non-significant. B: comparison of suppressive response durations. C: comparison of mean response magnitudes. D: comparison of peak response magnitudes. E: comparison of peak latencies.</p

Accuracy of vocalization discrimination based on the spike activities of single neurons in AAF and PAF.

<p>A: percentage of correctly discriminated vocalizations as calculated from the example neurons in Fig. 1 (circles) and 2 (triangles), respectively. The percentage of correct classification is plotted as a function of the bin size. Dotted line indicates the chance performance of discrimination (6.7%). B: percentage of correct classification for the population of AAF and PAF neurons as a function of the bin size. Circles (AAF) and triangles (PAF) are the mean values and the dots represent the SD.</p

Individual PSTHs depicting the response patterns of 92 AAF neurons to different stimuli.

<p>The absolute firing rates of each neuron were normalized to Z-scores and, for visualization purposes, smoothed and displayed in grayscale plots. PSTHs are aligned at the onset of tone. Black horizontal bars at bottom of plot show the duration of stimulus. Within each plot, neurons were ranked by the neuron’s BF.</p

Effectiveness of each stimulus to evoke a neural response.

<p>A and B: percentage of neurons showing an excitatory response to each stimulus in AAF and PAF. C and D: percentage of neurons showing a suppressive response to each stimulus in AAF and PAF.</p

Relation between response magnitude and BF.

<p>A and B: mean response magnitude of all 15 vocalizations versus the BF of AAF and PAF neurons, respectively. C: Energy distribution of our vocalization stimuli. Solid line indicates the mean SPL of the 15 vocalizations. Dotted line indicates the mean+SD. Each spectrum of vocalization was normalized by its maximum as 0, before calculating the mean and SD.</p