Localization of stimulating electrodes.

<p>Groups symbols were plotted in the same side for the sake of clarity. Abbreviations: DGLSC and DWLSC – deep gray and white layers of superior colliculus, DMPAG, DLPAG, LPAG and VLPAG – dorsomedial, dorsolateral, lateral and ventrolateral columns of the periaqueductal gray matter, DR – dorsal raphe, IC – inferior colliculus. Numbers refer to anteroposterior coordinates in relation to bregma of coronal plates of Paxinos and Watson's (1998) rat brain atlas <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0090726#pone.0090726-Paxinos1" target="_blank">[42]</a>.</p

Brain areas stimulated in controls (CTRL), sham-isolated rats (SHAM) and neonatally-isolated rats (NSI).

<p>DMPAG, DLPAG and LPAG – dorsomedial, dorsolateral and lateral columns of periaqueductal gray matter, DLSC – deep layers of superior colliculus.</p

Median threshold intensities (I₅₀±SE) of neonatally-isolated rats, sham-isolated rats and non-handled controls.

<p>Symbols represent values significantly different from controls (*) and sham-isolated rats (⁺) for Bonferroni's 5% criterion (likelihood ratio χ² tests for curve location).</p

Effects of neonatal social isolation on the performance of adult rats in the elevated plus-maze (<i>n</i> = 19–27) and forced swimming test (<i>n</i> = 18–24).

<p>Columns represent mean±SEM. CTRL – controls, SHAM – sham-isolated rats, NSI – neonatally-isolated rats. EAE – number of entries in enclosed arms (mean±SEM), OAE% - percent of entries in open arms, OAT% - percent of time in open arms. * P<0.005, statistically different from CTRL.</p

Intensity-response threshold curves of panic-like behaviors evoked by electrical stimulations of the dorsal periaqueductal gray matter.

<p>Curves are the best-fitted logistic functions of threshold response accumulated proportions in function of the logarithm of the stimulus intensity (µA). The abscissa is in logarithmic scale. Dashed lines (–) indicate significant differences between groups (P<0.05, likelihood-ratio χ² test for curve location). Abbreviations: r – responders, n –number of stimulated rats.</p

Protocol of neonatal social isolation (NSI).

<p>PN – postnatal day, ICS – intracranial stimulation, EPM – elevated plus-maze, FST-1 – forced swimming pretest session, FST-2 – forced swimming test session.</p