We used responses to large gratings (10°) drifting in 16 different directions (conditions averaged in Fig. 2A). To quantify across recording sites, we defined the preferred orientation (that inducing maximal gamma power) at each site to be 0°. The average power spectra for a subset of orientations are shown in Figure 2D (left; same n = 209 sites as in Fig. 2A). On average, gamma power at the preferred orientation was approximately twice that of the orthogonal orientations. However, the peak frequency of sugar daddy search Columbus Oh OH gamma was not significantly modulated by stimulus orientation, with the peak frequency at the preferred and orthogonal orientations nearly indistinguishable (36.8 ± 0.3 vs 36.6 ± 0.3 Hz, p = 0.6, t test; Fig. 2D, middle). When arranged by the preferred orientation of gamma power, spike rate tuning functions showed a response at the preferred orientation that was significantly <1, indicating that the preferred orientation defined by spike rates was often different from gamma at individual sites (Berens et al., 2008; Jia et al., 2011).

Model of gamma age group

We simulated the stimulus dependence of spiking activity and gamma power and peak frequency with a simple three component model, an extended but simplified version of the model developed by Kang et al. (2010). The model consisted of a local excitatory (E), local inhibitory (I), and global (G) excitatory component (see Fig. 1 and Materials and Methods). The local E and I components represent populations in a local V1 region, such as in a cortical hypercolumn. The local E and I components were recurrently connected-the excitatory component provided input to the inhibitory component (W_EI) and to itself (W_EE), and similarly for the inhibitory component (W_Ie and W_II). Both the E and I components also received external and independent Poisson-distributed input (I_E and I_I). This architecture captures the basic pyramidal-interneuron network gamma (PING) model, commonly used to model gamma generation (Bartos et al., 2007; Tiesinga and Sejnowski, 2009; Whittington et al., 2011).

The worldwide role integrates excitatory passion when you look at the several regional regions (W

The third component-the global or G component-represents a more spatially extensive mechanism. _Like), and affects both the local E and I components through excitatory connections (W_GE and W_GI, respectively). G might arise from long-distance horizontal connections between columns in V1 or feedback from higher visual areas (Angelucci and Bresslof, 2006). Figure 3, A and B, shows the behavior of the E component of the model for a small and large high contrast “gratings” (i.e., input), respectively. The mean activity of E is higher for the smaller stimulus. Spectral analysis shows the presence of elevated gamma frequency components in the activity of E, which are weaker and at a higher peak frequency for small gratings (centered around 50 Hz, Fig. 3C) than large gratings (?40 Hz, Fig. 3D). The peak frequency of gamma shifts lower as power increases because the time constant for the global component, recruited more strongly by the large stimulus, is slower than for the local E and I, lowering the resonant frequency of the network. Note that for both simulations gamma power fluctuates in time, consistent with previous analysis of physiological data (Burns et al., 2010a,b, 2011).

Analogy simulator answers. A great, Impulse of the Elizabeth component to a tiny grating (r = 3), since a purpose of date. Mention the brand new solid suggest impulse, in addition to presence away from transient gamma activity. Smaller gratings (r = some) lead stronger responses, however, too little gamma power to image in one single demo. B, Reaction of E element of a giant grating (roentgen = 5). Mention new ma ring passion. C, D, Spectrogram of your epochs found in A good and you may B, correspondingly. Gamma interest try weaker and at a high frequency toward quick grating. Spectra was calculated inside a moving 512 ms windows, established at that time expressed; spectra was in fact smoothed to have display just, of the convolving a-two-dimensional Gaussian kernel to the studies.