One possibility is that this rhythmic sampling mechanism may have evolved to ensure that

the neural processing of currently available information is not corrupted by potentially distracting information arriving in its immediate wake. It might also be that slow reverberatory activity may inject Osimertinib stochasticity into a neural circuitry that, coupled with attractor dynamics, helps mediate the tradeoff between exploratory and exploitative behavior (Soltani and Wang, 2008, 2010). Interestingly, unlike the neural encoding of decision-relevant information, which depended exclusively on the phase of delta oscillations, the gain of visual responses also followed the phase of faster cortical rhythms around 8 Hz. This finding is consistent with recent reports that evoked visual responses and signal detectability depend on the phase of EEG oscillations in this frequency range in humans (Busch et al., 2009; Wyart and Sergent, 2009; Scheeringa et al., 2011). The particular frequency of fluctuations in neural excitability may reflect the predominant time constants of synaptic activity in the corresponding

cortical area (Wang, 2010; Bernacchia et al., 2011). To conclude, we found that during extended categorical decisions, the rate of evidence accumulation fluctuates over time, in a fashion that can be predicted from the ongoing selleck inhibitor phase of slow EEG oscillations in the delta band (1–3 Hz) overlying human parietal cortex. Large-scale delta oscillations thus appear as an excellent candidate substrate for the serial attentional bottleneck known to give rise to a range of cognitive

phenomena such as the attentional blink and the psychological refractory period. These findings suggest that slow rhythmic changes in cortical excitability form a tight temporal constraint on sequential information processing. Sixteen students were recruited from the University of Oxford (age range: 18–25 years). All had normal or corrected-to-normal vision, and reported no history of neurologic or psychiatric disorders. They provided written consent before the experiment and received £30 in compensation for their participation, in addition to bonuses depending Isotretinoin on their categorization performance (approximately £5). The experiment followed local ethics guidelines. The data from one participant were not included because of excessive eye blinks. Visual stimuli were presented using the Psychophysics-3 Toolbox (Brainard, 1997; Pelli, 1997) and additional custom scripts written for MATLAB (The Mathworks). The display CRT monitor had a resolution of 1,024 × 768 pixels, a refresh rate of 60 Hz, and was gamma corrected using a decoding exponent of 2.2. Participants viewed the stimuli from a distance of approximately 80 cm in a darkened room.