From "A functional MRI study of high-level cognition": 
To investigate the neural basis of GO, Functional magnetic resonance imaging (fMRI) was used to measure brain activities of subjects engaged in playing go. Enhanced activations were observed in many cortical areas, such as dorsal prefrontal, parietal, occipital, posterior temporal, and primary somatosensory and motor areas.
Quantitative analysis indicated a modest degree of stronger activation in right parietal area than in left. This type of right hemisphere lateralization differs from the modest left hemisphere lateralization observed during chess playing.
Go players utilize and integrate analytic (left brain) and artistic/pattern recognition (right brain) functions.
See also: 
Working memory happens at the front of the brain, in the prefrontal cortex "This type of memory coordinates long-term memory with sights, sounds, feelings" Long term memory involves the hippocampus.
" Functional magnetic resonance imaging (fMRI) was used to measure brain activities of subjects engaged in playing go. Enhanced activations were observed in many cortical areas, such as dorsal prefrontal, parietal, occipital, posterior temporal, and primary somatosensory and motor areas." 
Jared: The listed regions cover a great deal of the brain. Least interesting are surely the somatosensory and motor areas. Most interesting is likely the prefrontal cortex.
The prefrontal cortex is the anterior part of the frontal lobes of the brain ... Divided into the dorsolateral, orbitofrontal and mesial prefrontal areas, this brain region has been implicated in planning complex cognitive behaviours ... 
The basic activity of this brain region is considered to be orchestration of thoughts and actions in accordance with internal goals. 
The most typical neurologic term for functions carried out by the pre-frontal cortex area is Executive Function. Executive Function relates to abilities to differentiate between conflicting thoughts, determine good and bad, better and best, same and different, future consequences of current activities, working toward a defined goal, prediction of outcomes, expectation based on actions ... 
The occipital lobes are the visual processing center of mammalian brains, yet are in the rear of the brain. 
The parietal lobe plays important roles in integrating sensory information from various senses, and in the manipulation of objects. Portions of the parietal lobe are involved with visuospatial processing. Much less is known about this lobe than the other three in the cerebrum. 
These contain discussions and bibliographies regarding mental activity in Go
- Help Yourself By Helping Your Body
- Blood Sugar levels and cognitive function
- Go as hierarchically ordered
- Player's Age
 Atherton, Michael, Zhuang, J. et. al.: A functional MRI study of high-level cognition: the game of chess. Cognitive Brain Research, 16/2003, 26-31. http://www.tc.umn.edu/~athe0007/CognitiveBrainResearchChess.pdf
 Xiangchuan Chen, Daren Zhang et. al.: A functional MRI study of high-level cognition. Cognitive Brain Research, 1/2002. University of Science and Technology of China, Department of Neurobiology and Biophysics, Hefei (China).