audiology 2012

<p>All other parameters as in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000092#pcbi-1000092-g010" target="_blank">Figure 10</a>. (A) Individual mean synaptic currents of all nonsensory nodes. (B) Total synaptic currents averaged across the nonsensory sheet. The injection of the externally evoked sensory currents into the prior activity actually has a slightly desynchronizing effect.</p

Spiking neurons network behavior as a function of the inhibition level

<p><b>.</b> (<b>A</b>) Mean synaptic current and (<b>B</b>) estimated Fisher information for the population receiving an extra bias . This quantity measures the network activity sensitivity to the bias and is calculated at bias Hz (black, blue and green curves, respectively). The Fisher information peaks around the excitatory and inhibitory synaptic currents balance. Due to noise in the data, it is almost impossible to distinguish the different curves.</p

INSI and NS magnitude histograms.

<p>(a) Experimental INSI distribution in one representative culture, using 500 ms time bins. The distribution is bimodal, with either very short INSIs (<1.5 s) or much longer ones (>6 s).The inset zooms on the long INSIs (>6 s) and uses a larger time bin (5 s). Notice the (somewhat) long tail: the distribution is positively skewed. (b) Conversely, the experimental NS magnitude distribution is unimodal and quite narrow (only the first NS of each BNS is taken into account). (c and d) Same histograms for the model, with and s (Note that we fitted the NS timescales, but not their magnitudes. Indeed, we do not know how many neurons each electrode picks on average; therefore we cannot estimate the true average number of spikes per second per neuron).</p

Fatigue timescales' separation.

<p>For panels (a–b)  = 1.6 s, while for panels (c–d)  = 1.2 s. In all cases,  = 0.8 s,  = 1.6 s, and W₀ = 8.6 (a) Mean population firing rate as a function of time. (b) Adaptation leak conductance g_a (population-averaged) as a function of time. Inside a BNS, it tends to accumulate across successive NSs, until it is high enough to prevent subsequent NSs. Thus BNS termination is almost deterministic, while BNS initiation is stochastic. (c) Mean population firing rate as a function of time. (d) Adaptation leak conductance g_a (population-averaged) as a function of time. It cannot accumulate across successive NSs. Thus both BNS initiation and termination are stochastic. This can lead to hundreds of ms long BNSs, which is not realistic.</p

Working point.

<p>Each curve corresponds to all the possible (Mean IBNSI, CV) points that the model can reach by varying the recurrent excitatory weight W₀ (see values in italic), keeping constant. Simulations stopped when 300 BNSs were recorded (with an additional 5h limit). Cases with less than 100 BNSs were discarded. The boxes represent 95% confidence intervals (estimated with bootstrapping), for both CV and mean IBNSI. We fitted a Poisson-with-refractory-period model CV  =  (mean-T)/mean for each value. The legend shows estimated refractory periods T, with 95% confidence intervals, and the coefficients of determination R². Gray circles represent the experimental cultures, and the numbers inside are the corresponding days in vitro (DIV), which did not correlate with the mean INSIs, or the CV. The horizontal gray line materializes the asymptotic limit CV = 1.</p

Fano factor reduction as a function of the inhibition level in the biased competition case for cohesion level

<p><b>.</b> Two selective populations receive a stimulus, and attention is allocated to one of them. The Fano factor is averaged over the neurons in each stimulated population. Fano factor reduction (<b>A</b>) for the attended stimulus corresponding population and (<b>B</b>) for the non-attended one.</p

Fano factor as a function of the cohesion and inhibition levels in the (A) non-matched rate and (B) matched rate conditions.

<p>Fano factor (top) without and (middle) with external stimulation ( Hz) and (bottom) their difference, i.e. the stimulus driven reduction of the Fano factor. The difference in Fano factor between two consecutive contours is . For the Fano factor reduction, the interval is indicated by the light blue color, and values less than are indicated in white. These results show that a reduction of the Fano factor consistent with the experiments occurs indeed around the bifurcation line, for sufficient inhibition ().</p

Mean TE as a function of gamma frequency band power.

<p>We plot the TE for six different / modification ratios (solid line). A higher / modification ratio causes the network to oscillate in the gamma frequency range and thus increases the power in the gamma frequency band (dashed line). Error bars indicate 95% confidence intervals; averaged over 100 trials.</p

Fano factor without and with attention in the case of one stimulus.

<p>After ms of stimulus presentation to a given selective population (with rate Hz), attention is allocated (with bias Hz) (red curve). Comparison to the case without attention (blue curve).</p

Spearman rank correlation coefficient.

<p>The rank correlation between the 60 Hz power in two neuronal pools is plotted as a function of the phase shift in the gamma band. A phase shift of zero represents the mean phase shift which is the point where the rank correlation is highest. The solid line indicates a cosine fit.</p