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Dissociating the white matter tracts connecting the temporo-parietal cortical region with frontal cortex using diffusion tractography.

ABSTRACT: Three major white matter pathways connect the posterior temporal region and the adjacent inferior parietal lobule with the lateral frontal cortex: the arcuate fasciculus (AF), and the second and third branches of the superior longitudinal fasciculus (SLF II and SLF III). These pathways are found also in nonhuman primate brains where they play specific roles in auditory and spatial processing. The precise origin, course, and termination of these pathways has been examined in invasive tract tracing studies in macaque monkeys. Here we use this prior knowledge to improve dissections of these pathways in vivo in the human brain using diffusion Magnetic Resonance Imaging (MRI) tractography. In this study, the AF, originating from the posterior temporal cortex, has been successfully separated from the SLF II and SLF III tracts originating from the angular and supramarginal gyri of the inferior parietal lobule, respectively. The latter two pathways, i.e. SLF II and SLF III, have also been clearly separated from each other. Furthermore, we report for the first time in the human brain the dorsal branch of the AF that targets the posterior dorsolateral frontal region. These improved dissection protocols provide a solid basis for exploring the respective functional roles of these major fasciculi.

SUBMITTER: Barbeau EB

PROVIDER: S-EPMC7235086 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Dissociating the white matter tracts connecting the temporo-parietal cortical region with frontal cortex using diffusion tractography.

Barbeau Elise B EB Descoteaux Maxime M Petrides Michael M

Scientific reports 20200518 1

Three major white matter pathways connect the posterior temporal region and the adjacent inferior parietal lobule with the lateral frontal cortex: the arcuate fasciculus (AF), and the second and third branches of the superior longitudinal fasciculus (SLF II and SLF III). These pathways are found also in nonhuman primate brains where they play specific roles in auditory and spatial processing. The precise origin, course, and termination of these pathways has been examined in invasive tract tracin ...[more]

PMID: 32424290

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Project description:Apathy is an uncertain nosographical entity, which includes reduced motivation, abulia, decreased empathy, and lack of emotional involvement; it is an important and heavy-burden clinical condition which strongly impacts in everyday life events, affects the common daily living abilities, reduced the inner goal directed behavior, and gives the heaviest burden on caregivers. Is a quite common comorbidity of many neurological disease, However, there is no definite consensus on the role of apathy in clinical practice, no definite data on anatomical circuits involved in its development, and no definite instrument to detect it at bedside. As a general observation, the occurrence of apathy is connected to damage of prefrontal cortex (PFC) and basal ganglia; "emotional affective" apathy may be related to the orbitomedial PFC and ventral striatum; "cognitive apathy" may be associated with dysfunction of lateral PFC and dorsal caudate nuclei; deficit of "autoactivation" may be due to bilateral lesions of the internal portion of globus pallidus, bilateral paramedian thalamic lesions, or the dorsomedial portion of PFC. On the other hand, apathy severity has been connected to neurofibrillary tangles density in the anterior cingulate gyrus and to gray matter atrophy in the anterior cingulate (ACC) and in the left medial frontal cortex, confirmed by functional imaging studies. These neural networks are linked to projects, judjing and planning, execution and selection common actions, and through the basolateral amygdala and nucleus accumbens projects to the frontostriatal and to the dorsolateral prefrontal cortex. Therefore, an alteration of these circuitry caused a lack of insight, a reduction of decision-making strategies, and a reduced speedness in action decision, major responsible for apathy. Emergent role concerns also the parietal cortex, with its direct action motivation control. We will discuss the importance of these circuits in different pathologies, degenerative or vascular, acute or chronic.

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Dissociating the white matter tracts connecting the temporo-parietal cortical region with frontal cortex using diffusion tractography.

Publications

Dissociating the white matter tracts connecting the temporo-parietal cortical region with frontal cortex using diffusion tractography.

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