Bilateral cingulotomy
Studies in patients that were a subject to bilateral cingulotomy, that involved fMRI analyses, showed that the anterior cingulate cortex has a key role in cognitive control and is highly likely to be involved in the control of attentional response, whereas the dorsal part of that region of the brain was not identified to be involved in such a process, although this is still under dispute. The function of the dorsal part of the cingulate cortex was connected to the sorting out and processing of conflicting information signals. In addition, neuroimaging studies also indicated that the anterior cingulate cortex participates in the modulation of cortical regions that are of higher order as well as sensory processing areas.
Effects of sleep deprivation on cognitive performance
The anterior cingulate cortex has been implemented in the process of inhibiting a habitual response or detecting possible conflicts in responses; this is shown by the Stroop test. Studies have found that as little as 36 hours of sleep deprivation cause a performance reduction in tasks requiring these executive functions.
The processes above illustrate a model of controlled versus automatic behavior that was hypothesized by Shallice et al. (1989), called the supervisory attentional system. This system is believed to come into play when intervention of habitual response is necessary. Damage to the prefrontal cortex will cause a breakdown in this system, resulting in utilization behaviors. These behaviors would include spontaneous sequences of action on irrelevant objects in the surroundings with no clear goal in mind. This theory has helped to extend the knowledge we now have on executive functions.