This reminds me of 'absence seizures', something that's been reported for a long time:
http://www.epilepsy.com/learn/types-seizures/absence-seizures
http://en.wikipedia.org/wiki/Absence_seizure
http://www.webmd.com/epilepsy/guide/understanding-absence-seizure-basics
Simple absence seizures: During a simple absence seizure, a person usually just stares into space for less than 10 seconds. Because they happen so quickly, it’s very easy not to notice simple absence seizures — or to confuse them with daydreaming or not paying attention.
Complex absence seizures: During a complex absence seizure, a person will make some kind of movement in addition to staring into space. Movements may include blinking, chewing, or hand gestures. A complex absence seizure can last up to 20 seconds.
Right, it seems similar. However, the memory of absence seizures is partially retained, so consciousness is not necessarily completely off:
while verbal responses were very often interrupted during seizures, some patients recalled questions or commands given during a seizure, and responded appropriately after the seizure ended
See also this review:
...electrical stimulation of the claustrum, in a conscious patient with intractable complex partial epilepsy undergoing a preoperative investigation, produces a clinical state of immobility and complete lack of
This paper, or more often the New Scientist's exposition of it is being discussed online and is rather topical here. In a nutshell, stimulating one small but central area of the brain reversibly rendered one epilepsia patient unconscious without disrupting wakefulness. Impressively, this phenomenon has apparently been hypothesized before, just never tested (because it's hard and usually unethical). A quote from the New Scientist article (emphasis mine):
One electrode was positioned next to the claustrum, an area that had never been stimulated before.
When the team zapped the area with high frequency electrical impulses, the woman lost consciousness. She stopped reading and stared blankly into space, she didn't respond to auditory or visual commands and her breathing slowed. As soon as the stimulation stopped, she immediately regained consciousness with no memory of the event. The same thing happened every time the area was stimulated during two days of experiments (Epilepsy and Behavior, doi.org/tgn).
To confirm that they were affecting the woman's consciousness rather than just her ability to speak or move, the team asked her to repeat the word "house" or snap her fingers before the stimulation began. If the stimulation was disrupting a brain region responsible for movement or language she would have stopped moving or talking almost immediately. Instead, she gradually spoke more quietly or moved less and less until she drifted into unconsciousness. Since there was no sign of epileptic brain activity during or after the stimulation, the team is sure that it wasn't a side effect of a seizure.
If confirmed, this hints at several interesting points. For example, a complex enough brain is not sufficient for consciousness, a sort-of command and control structure is required, as well, even if relatively small. A low-consciousness state of late-stage dementia sufferers might be due to the damage specifically to the claustrum area, not just the overall brain deterioration. The researchers speculates that stimulating the area in vegetative-state patients might help "push them out of this state". From an AI research perspective, understanding the difference between wakefulness and consciousness might be interesting, too.