, 2004). The interregional functional connectivity was obtained by computing Pearson correlation coefficients for all possible this website pairs of ROIs. We computed statistical tests on all correlations after applying the Fisher Z-transform, which yields variates that are approximately normally distributed. The monkey sat in a customized primate chair, alone in
a completely dark room to avoid visual stimulation and minimize eye movements (Martinez-Conde et al., 2004). We acclimatized the monkey to this resting-state condition prior to recordings. The monkey had no behavioral requirements and was free to move his eyes (however, we analyzed epochs in which the eyes were stable, except for the correlation analyses on long data epochs, to allow comparison SCH772984 molecular weight with the literature). We monitored eye movements using a stationary eye-tracking system (Applied Science Laboratories) with an infrared camera operating at 120 Hz. The LFP from each electrode was amplified and band-pass filtered (3–300 Hz; precluding assessment of delta band oscillations) using
a preamplifier (PBX3/16sp-r-G1000/16fp-G1000, with a high input impedance headstage; Plexon) and Plexon Multichannel Acquisition Processor controlled by RASPUTIN software. The signals were digitized at a rate of 1,000 Hz. In total, 58 resting-state sessions (on separate days) were acquired from two monkeys (CA, 39 sessions; LE, 19 sessions). Analysis of LFPs. We performed data analyses in MATLAB using the Chronux toolbox ( Bokil et al., 2010). Preprocessing steps included the exclusion of artifacts
from any body movements and the removal of 60 Hz power signal peptide line noise and its harmonics using a notch filter (±1 Hz). We identified stable-eye epochs of at least 700 ms duration, during which the monkey’s eyes did not deviate by more than 2°. We calculated band-limited power (BLP) correlations and coherence in 500 ms windows within each stable-eye epoch after excluding (1) the first 200 ms of stable-eye epochs to remove any evoked responses, and (2) the 210 ± 141 ms (mean ± SD) before the next eye movement to remove any possible motor-related signals; if the stable-eye epoch spanned multiples of 500 ms (after excluding the first 200 ms of the epoch), each of these 500 ms data segments contributed to the analyses. BLP and Correlation Analysis. To examine BLP modulation in different frequency bands, we applied zero phase-shift band-pass filtering to the raw LFP signals to produce the following frequency bands: theta, 4–8 Hz; alpha, 8–13 Hz; beta, 13–30 Hz; and gamma, 30–100 Hz. We also probed effects at a higher-frequency resolution in the following bands: 4–8 Hz, 8–13 Hz, 13–20 Hz, 20–30 Hz, 30–40 Hz, 40–50 Hz, 50–60 Hz, 60–70 Hz, 70–80 Hz, 80–90 Hz, and 90–100 Hz. To normalize the resulting band-limited signals, we subtracted the mean power and divided by the SD for that frequency band.