Fiber Tractography Lab Projects

High-Definition Fiber Tractography (HDFT) is an advanced MRI-based non-invasive imaging technique that is being used in our lab—under the direction of Fang-Cheng (Frank) Yeh, MD, PhD—to study the intrinsic structure and connectivity of the living human brain, both in normal subjects and neurosurgery/neurology patients.

Fiber Tractography

Neuroanatomy of Fiber Tracts

Nearly two decades ago, Sir Francis Crick, neuroscientist, discoverer of the DNA molecule and 1962 Nobel Prize for Medicine, wrote: “to interpret the activity of living human brains, their neuroanatomy must be known in detail. New techniques to do this are urgently needed, since most of the methods now used on monkeys cannot be used on humans.” Nowadays, HDFT allows doctors and scientists to investigate the intrinsic structure of the brain with unprecedented detail, which will invariably facilitate a better understanding of brain functioning.

Studies in the Fiber Tractography Lab have contributed to elucidate the structure and connectivity of the Middle Longitudinal Fascicle showing that interconnects the superior temporal gyrus with the superior parietal lobule and parieto-occipital region. Based on the roles of these interconnected cortical regions, it is hypothesized that the MdLF may contribute to the dorsal “where” pathway of the auditory system.

We have also studied the asymmetry, connectivity, and subsegmentation of the arcuate fascicle, confirming the highly leftward asymmetry of this tract as well as the existence of a strong structural subsegmentation in the left arcuate, but not in the right one. We proposed the existence of primary and supplementary language pathways within the dominant arcuate fascicle with potentially distinct functional and lesional features.

There are other ongoing research projects regarding the connectivity of the superior longitudinal fascicle, the superior fronto-occipital fascicle, the claustrum, and the thalamic radiations.

Fiber Tractography

Presurgical Assessment of Fiber Tracts and Surgical Planning

HDFT provides a superior presurgical evaluation of the fiber tracts for patients with complex brain lesions. Our presurgical studies are built upon precise and accurate neuroanatomical knowledge, which allows us to reconstruct fiber tracts and design the less invasive trajectory into the target lesion.

Our clinical experience applying HDFT has been reported in Neurosurgery, and we have are currently investigating its potential for not only presurgical planning and intraoperative navigation but also for neurostructural damage assessment, estimation of postsurgical neural pathways damage and recovery, and tracking of postsurgical changes and responses to rehabilitation therapy.

The ultimate goal is to facilitate brain function preservation and recovery in patients undergoing complex brain surgery.

Fiber Tractography

Fiber Tract Integrity and Damage Progression in Neurodegenerative Disorders

We are currently studying patients with ALS and Huntington Disease aiming to obtain quantifiable measures of white matter tract integrity that can be correlated with the speed of disease progression and with clinical measures. The ultimate goal is to find an accurate biomarker of the disease that can be monitored and serve as a reference for treatment response.

Language Connectivity Pathways and Neuroplasticity in Aphasic Stroke Patients

We are correlating specific white matter tract disconnections evidenced by HDFT with phonological and semantic deficits aiming to improve our understanding of language related pathways. We are also investigating the neuroplasticity in this stroke population by determining whether targeted intensive behavioral therapy induces structural neuroplastic changes in perilesional and/or contralateral fiber tracts of aphasic patients and whether any observed neuroplastic changes are correlated with behavioral improvements and predict the potential for speech recovery.