Reducing intracortical inhibition in the adult visual cortex promotes ocular dominance plasticity - PubMed (original) (raw)

Figure 2.

Reduction of cortical inhibition promotes OD plasticity in adult rat visual cortex. Top, Experimental protocol. a, Monocular deprivation is ineffective in adult control rats; left and middle, OD distribution for normal, nondeprived (Nor) (N = 5; 115 cells) and saline-treated, monocularly deprived adult rats (MD) (N = 4, 117 cells) do not significantly differ (χ2 test, n = 4, p > 0.05); right, same data represented as cumulative fraction of OD scores: the curve for normal animals (Nor) and control MD animals (MD) do not significantly differ [Kolmogorov–Smirnov (K-S) test, p > 0.05]. The cumulative fraction values represent the fraction of cells with an OD score less than or equal to a given OD score value. b, c, Left and middle, OD distributions for MPA-treated nondeprived (MPA) (N = 3, 90 cells); MPA-treated, monocularly deprived (MPA+MD) (N = 5, 147 cells); PTX-treated nondeprived (PTX) (N = 4, 98 cells); PTX-treated, monocularly deprived (PTX+MD) (N = 3, 91 cells) rats. Both MPA+MD and PTX+MD distributions are significantly shifted toward the nondeprived eye (ipsilateral eye) with respect to those for normal, MD, MPA, and PTX animals (p < 0.001, χ2 test; _n_ = 4). MPA and PTX treatment without deprivation does not modify the OD distribution (χ2 test, _n_ = 4, _p_ > 0.05); right, same data represented as cumulative fractions of OD scores. The curves for the MPA+MD and PTX+MD groups are significantly shifted to the right (i.e., toward the nondeprived eye) with respect to those in normal and in treated nondeprived animals (K-S test, p < 0.05). Curves for undeprived MPA- or PTX-treated animals do not differ from that in normal animals (K-S test, _p_ > 0.05). d, Functional properties of visual cortical neurons in the recorded animals. Left, Mean RF size, expressed in degrees (deg) of visual angle (±SEM); data for deprived and nondeprived MPA- or PTX-treated animals have been pooled together (no statistical difference, two-tailed t test). Normal (Nor) (115 cells), MPA-treated (MPA) (237 cells), and PTX-treated animals were recorded during the treatment (PTX) (189 cells). RFs are larger with respect to normal (one-way ANOVA, p < 0.001, Holm–Sidak _post hoc_ test) both in MPA- and PTX-treated rats. Middle and right, Data for peak response and peak-to-baseline ratio are represented as box charts. For each box chart, the central horizontal line is the median value, and the other two horizontal lines are the 25 and 75% interquartile values; the filled square is the mean value, and the vertical bars are the 5 and 95% interquartile values. Peak response differs from normal only for MPA animals (one-way ANOVA, _p_ < 0.05, _post hoc_ Dunn's test); peak-to-baseline ratio (a measure of cell responsiveness) is unaffected by the treatments (one-way ANOVA, _p_ > 0.05).