**5. Applications of normative connectome (including DBS)**

As a powerful tool to study the intriguing network in the brain, normative connectome can be used in different areas.

First, normative connectome can unveil the underlying complicated pathways of various neurological and psychiatric diseases and so may bring insights to the identification of new treatment targets. Let us take **Figure 1** as an example. By mapping the connectomes of a group of patients with visual hallucination, lesions that cause the symptom were found to be connected to the occipital cortex. This aid in the discovery of novel treatment targets, as in this example, transcranial magnetic stimulation at the occipital cortex can suppress visual hallucination [50].

Second, normative connectome can enhance surgical precision and hence improve treatment outcome of different neurosurgical procedures. For instance, for glioma patients who plan for resection surgery, the application of normative connectome can help in the identification of eloquent areas and motor tracts before operation, hence reducing the number of intra-operative stimulations required to safely confirm a tract, decreasing the likelihood of disruptive seizures, lowering the risks of postoperative neurological deficits, facilitating the resection, and making patients more comfortable during the operation [51, 52]. Epilepsy surgery is another example. It has been reported that with the use of connectome, the surgical outcome of epilepsy surgery can be improved and the risks of post-operative neurocognitive sequelae, including memory and language impairment, can be reduced [53–56].

Last but not the least, normative connectome has been used widely in the field of neuromodulation, especially DBS. Theoretically, DBS works by depolarization blockade, synaptic inhibition and depression, as well as, stimulation-induced modulation of pathological network activity, of which is regarded the most important mechanism of action [57, 58]. Thus, when normative connectome allows us to map out the pathological pathways in the brain, stimulation at certain points along the circuits may restore the disrupted information flow and so alleviate patients' symptoms. Besides, DBS electrodes, which function as probes, can become *seeds* or regions-of-interest

*Perspective Chapter: Functional Human Brain Connectome in Deep Brain Stimulation (DBS)… DOI: http://dx.doi.org/10.5772/intechopen.109855*

(ROIs) when they are used to compute their connectivity profiles with normative connectome to perform network-based analyses. In this way, we can identify the optimal site for stimulation and avoid undesirable side effects, thereby facilitating DBS programming and improving surgical outcome [59].
