Figure 4.
Characteristics of spontaneous retinal waves and visual cortex SATs. A, Extracellular recording of spontaneous activity from an acutely excised retina (P10) shows repetitive, long-duration burst clusters separated by long quiet periods consistent with phase III retinal waves described in mice (Kerschensteiner and Wong, 2008; Blankenship et al., 2009) and similar in structure to SATs observed in visual cortex. B, Box plot presentation of duration (left), interevent interval (middle), and number of bursts (right) for V1 SATs and retinal burst clusters (n = 10 SATs from each of 8 P10–P11 pups, 10 burst clusters from each of 10 P10–P11 retinas). Middle line shows median, the box ends at the 25th and 75th percentiles, and the whiskers show the total range. Outliers (>1.5 times the intraquartile distance) are plotted with asterisks. Notches show the comparison interval (95% confidence). For each parameter, the distributions of retinal waves and V1 SATs overlap and are not significantly different (Mann–Whitney U test, p > 0.05), suggesting that the occurrence, duration, and burst structure of cortical SATs are determined by retinal activity. C, Autocorrelation of MUA spike rate (5 ms bins) from layer 4 V1 and retina, same population as B. Dark line indicates mean, and dotted line indicates SD. V1 recordings display evidence of structure in the autocorrelation as a result of the beta-band oscillations, whereas retinal recordings display only a simple drop off with time. This suggests a nonretinal (i.e., thalamic or cortical) generator for the rapid oscillations. D, Increasing retinal wave initiation via intraocular injection of Bic and Str (Blankenship et al., 2009) increases occurrence of visual cortex SATs. After control ACSF injection, repetitive SATs are observed as in non-injected rats (top trace). Bic + Str injection (10 min) caused a massive increase in the occurrence of SATs (bottom trace). E, Interevent interval distribution after ASCF and Bic + Str injection. Control cortical activity (black lines) showed a bimodal distribution with a large shoulder at 20–60 s. After injection (gray lines), the interval shifted to an exponential distribution (n = 50 events from each of 5 P10–P11 pups). Dotted lines indicates 95% confidence interval. F, Percentage change in power spectral density (1–50 Hz) after intraocular injection (30 min recordings from 5 animals; error bars indicate SEM). Increasing retinal wave initiation selectively increased beta-band oscillations.