Transferring enriched environment-mice to standard cages (SCs) immediately abolished ocular dominance-plasticity.

<p>Intrinsic signal imaging of V1-activation in EE→SC-mice after MD, and its quantification. MD was induced after 1 day (1d) or one week (1w) in SC. Layout and data display as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186999#pone.0186999.g001" target="_blank">Fig 1</a>.</p

Ocular dominance-shifts happen already after 2 days of monocular deprivation in adult enriched environment mice.

<p>Chronic imaging of V1-activation in enriched environment (EE)-mice before and after monocular deprivation (MD), and its quantification. <b>A</b>: V1-activity maps of a P143 EE-mouse after visual stimulation of the contra- (contra) and ipsilateral (ipsi) eye, before (noMD, first row) and after 2/4 days of MD (second/third row). Layout and data display as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186999#pone.0186999.g001" target="_blank">Fig 1</a>. <b>B-E</b>: Ocular dominance indices (B), average V1-activation (C) and individual V1-activation after deprived and open eye stimulation before and after MD of the three chronically imaged EE-mice.</p

Adding a running wheel to standard cages but not fluoxetine treatment rescued ocular dominance plasticity after transferring EE-mice to SCs (EE→SC).

<p>Examples of V1-activity maps and their quantification recorded from EE-mice transferred to SCs: EE->SC-mice without treatment (upper 2 rows), with fluoxetine treatment (3^rd and 4^th row), or with added RW in the SCs (5^th row). Layout and data display as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186999#pone.0186999.g001" target="_blank">Fig 1</a>. MD only induced an OD-shift in V1 of the RW-group (EE→SC_RW): after MD, the contra- and ipsilateral eye activated V1 about equally strong, colder colors appeared in the OD-map, and the histogram of OD-scores shifted to the left (blue arrow). In all other groups, including those treated with fluoxetine, V1 remained dominated by input from the contralateral (deprived) eye: contralateral eye evoked activity patches were darker than those of the ipsilateral eye, the average ODI was positive, and warm colors prevailed in the OD-maps. Scale bar: 1 mm.</p

Contrast sensitivity thresholds before and after monocular deprivation period.

<p>Contrast sensitivity thresholds before and after monocular deprivation period.</p

Quantification of optically recorded V1-activation in enriched environment-mice of three different age groups before and after varying monocular deprivation durations.

<p><b>A.</b> Optically imaged ODIs of critical period, young and old enriched environment (EE) mice. Symbols represent individual ODI-values, means are marked by horizontal lines; values after monocular deprivation (MD) are indicated by half-black squares. <b>B.</b> V1-activation elicited by stimulation of the contralateral (C) or ipsilateral (I) eye without and with MD (black filled circle indicates MD eye).</p

ODIs and V1-activation of EE-mice transferred to standard cages (SCs).

<p><b>A.</b> Optically imaged ODIs without and with MD of EE-mice transferred to SC for one week (EE→SC1_w) or one day (EE→SC1_d) before MD (white), EE→SC_-fluox (light grey), EE→SC_+fluox (dark grey) and EE→SC_RW mice (red). <b>B.</b> V1-activation elicited by stimulation of the contralateral (C) or ipsilateral (I) eye without and after MD. Only in EE→SC_RW mice showed an OD-shift after MD: both eyes activated V1 about equally strong whereas in all other groups, V1 continued to be dominated by the previously deprived contralateral eye. Layout and data display as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186999#pone.0186999.g003" target="_blank">Fig 3</a>.</p

Increase of optomotor thresholds of the open eye after monocular deprivation in enriched environment -mice.

<p>Gain on baseline [%] of spatial frequency thresholds of the optomotor reflex, determined by optomotry, plotted for the three different age groups of EE-mice and separated for the various MD-durations.</p

Accelerated ocular dominance (OD) shifts in V1 of enriched environment (EE) mice.

<p>Representative examples of optically recorded activity maps in the binocular region of V1 of animals of three different age groups: critical period (P24-35), young (P90-104) and old EE-mice (P117-283), before and after 1, 2, 4 or 7 days (d) of monocular deprivation (MD). Grayscale-coded V1-activity maps (neuronal activation expressed as fractional change in reflectance ×10⁻⁴) after contralateral (contra) and ipsilateral (ipsi) eye stimulation (numbers correspond to quantified V1-activation of the illustrated example), color-coded 2-dimensional OD-maps and the histogram of OD-scores, including the average ocular dominance index (ODI) are illustrated. Without MD, activity patches evoked by stimulation of the contralateral eye were darker than those of the ipsilateral eye, the average ODI was positive, and warm colors prevailed in the OD-maps, indicating contralateral dominance. MD of 1–2 days already induced strong OD-shifts towards the open eye: after MD, contra- and ipsilateral eye stimulation activated V1 about equally strong, colder colors appeared in the OD-map, and the histogram of OD-scores shifted to the left (blue arrows). Scale bar: 1 mm.</p

Fluoxetine treatment had no effect on V1-activation nor on the quality of the optically recorded V1-maps.

<p>Retinotopic polar and activity maps after visual stimulation with moving horizontal (elevation) or vertical (azimuth) bars (see inset to the left of the V1-maps) recorded from EE→SC mice control (water) or fluoxetine treatment, and their quantification. Comparison of V1-activation (lower left) and map quality (lower right) after contralateral (right) eye stimulation in both control (water, grey) and fluoxetine-treated (red) mice, for both elevation and azimuth stimulation. Recorded V1-maps of both treatment groups were indistinguishable in signal strength and retinotopic map quality. Scale bar: 1 mm.</p

Experience-enabled enhancement of the optomotor reflex of the open eye of enriched mice transferred to a standard cage after monocular deprivation (MD).

<p>Both spatial frequency (A) and contrast sensitivity thresholds (B) of the optomotor response before and after MD are compared in control mice, animals treated with fluoxetine or with access to a RW. <b>A.</b> Spatial frequency thresholds in cycles per degree (cyc/deg) are plotted against days. Half-filled boxes indicate MD-groups. After 7 days of MD, thresholds improved significantly compared to mice without MD. <b>B.</b> Contrast sensitivity thresholds at 6 different spatial frequencies before (day 0) and 7 days after MD of EE→SC_-fluox, EE→SC_+fluox and EE→SC_RW mice with or without MD. Threshold values of all groups improved significantly after MD at all tested spatial frequencies compared to the noMD groups (filled boxes).</p