Destexhe et al., 2001, Freeman, 1979 and Rajagovindan and Ding, 2010). The basic idea is that an increase in excitation in a task relevant network depends on background/spontaneous activity. The larger this activity is, the larger the gain. This relationship is not linear but obeys a sigmoidal function. The important point for our theory is that we have to consider two functions, one for excitatory and another for inhibitory activity. The latter regulates the local inhibitory gain in the task relevant network in order to optimize SNR. This means that the inhibitory background

activity and the event-related inhibitory gain depend on the excitatory background U0126 price activity and the excitatory event-related gain. As a consequence, in order to increase the SNR in task relevant networks inhibition will increase as excitation increases. These considerations suggest that the P1 reflects the event related change in background inhibitory activity

and allows the following predictions. (i) For task relevant networks, an inverted U-shaped function may be predicted between prestimulus (ongoing) alpha power (reflecting inhibitory background activity) and P1 amplitude (reflecting the event related change in inhibition), provided check details phase locking does not play a specific or interfering role. The inverted U-shaped function simply means that beyond a certain level of background activity, the level of event-related inhibition is reduced

in order to avoid blocking of information processing in task relevant networks. This prediction is very similar to that BCKDHA of Rajagovindan and Ding (2010) with the only but important difference that (according to their view) the inverted U-shaped function (between ongoing alpha and P1 amplitude) is thought to reflect excitatory processes. (ii) For task competing networks, there is no need to control/modify the SNR. Thus, inhibition may be set to a certain level (depending again on excitation), which does not reflect the local inhibitory gain (and the modulation of SNR) but the blocking of information processing. I am grateful for insightful and critical discussions with my colleagues Robert Fellinger and Roman Freunberger. I am also very grateful for critical comments of 3 Reviewers who helped to improve earlier drafts of this article. “
“In the July 1998 issue of Brain Research, we used Figures 5A and 5B which had been already published as Figures 5A and 5B in our previous paper published in Critical Care Medicine 25; 874–879:1997. Although we cited our previous paper as reference 26 in our paper by Taoka, et al., we unintentionally missed the attribution of Figures 5A and 5B in the figure legend of our paper by Taoka, et al. The correct figure legend is as follows: Figure 5.