Peter Lakatos and Charlie Schroeder have conducted elegant work showing that the brain entrains its rhythms to attended sensory inputs.  Here, Lakatos et al show that normal human subjects show increased rhythmic entrainment with increasing task demands,  By contrast, schizophrenic patients are less able to match their brain rhythms to attended stimuli, even when the task is highly demanding.

Miller Lab work cited:
Buschman, T.J. and Miller, E.K. (2007) Top-down versus bottom-up control of attention in the prefrontal and posterior parietal cortices. Science. 315: 1860-1862  The Scientist’s “Hot Paper” for October 2009. View PDF »

Buschman, T.J. and Miller, E.K. (2009) Serial, covert, shifts of attention during visual search are reflected by the frontal eye fields and correlated with population oscillations. Neuron, 63: 386-396. View PDF »

Matt Chafee and crew show that monkeys under the influence of ketamine show similar deficits as human schizophrenia patients on a test of context processing.
Blackman et al 2013