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be responsible for sensations such as hunger and pain, while the other could be a crossroads for information from every corner of the cortex. + Medial subnetworks — These two subnetworks occupy a central area in the cortex. Researchers postulated that the subnetworks may consolidate visual, auditory and spatial information. + Somatic sensorimotor subnetworks — Each of these four subnetworks controls a different part of the body, including torso and hind limbs, front limbs, facial muscles, and whiskers. Two other newly identified regions displayed high degrees of interaction with most of the cortex, indicating they might be critical areas for sending and receiving information. "What excited us most was that although the cortex is comprised of many individual regions that all appear to be connected, it actually displayed a very logical organiza- tion that grouped selected cortical regions with one another into these subnetworks," Dr. Dong says. "The functional assignments of these subnetworks need to be investigated further with appropriate behavioral studies; however, existing behavior and physiological data on these cortical structures provide clues to their roles." Disconnection and Disease The similarities between the mouse brain and the human brain make the rodent an ideal subject for obtaining insights about the human brain that researchers might never be able to glean otherwise. "Although the human brain is much more complex than the rodent's, the two organs share many common organizational principles," Dr. Dong says. "Technical limitations and ethical issues may make it impossible to map the human brain in the same resolution and comprehensiveness as what we can achieve with the mouse brain." MCP researchers' efforts to understand the order of brain connections may be the fi rst step toward developing a clearer picture of what happens when those connections are interrupted or function improperly. " M a ny p s y c ho p a t holo g ic a l a nd neurological diseases are now being identifi ed as pathologies of connections," Dr. Hintiryan says. "Brain regions don't work independently to control a behavior — their interactions and connections with other brain structures result in a desired behavioral output. As such, in a diseased state, it's the connections among the structures that are affected. The fi rst step in identifying these diseased connections is to gain a solid understanding of how these networks are inherently organized in healthy brains. Subsequently, we can examine aberrant connections within these networks in a variety of disorders. We want to avoid going beyond our data, but we feel the literature provides some strong evidence for cortical connection pathologies in attention defi cit hyperactivity disorder, schizophrenia and Alzheimer's disease." A driving force behind the MCP is the desire to give clinicians more options to treat those conditions. "Our group is seeking an opportunity to map the neuronal connectivity in different mouse models of neurological/neuropsy- chiatric diseases using our well-developed connectomic approach," Dr. Dong says. "That will provide more direct evidence for understanding the etiology of the 'discon- nection syndromes' and provide valuable reference for exploring novel treatments." ■ M D N E W S . CO M ■ MD NEWS Greater Boston | 1 3