Development of the uncinate fasciculus: Implications for theory and developmental disorders

Abstract

The uncinate fasciculus (UF) is a long-range white matter tract that connects limbic regions in the temporal lobe to the frontal lobe. The UF is one of the latest developing tracts, and continues maturing into the third decade of life. As such, individual differences in the maturational profile of the UF may serve to explain differences in behavior. Indeed, atypical macrostructure and microstructure of the UF have been reported in numerous studies of individuals with developmental and psychiatric disorders such as social deprivation and maltreatment, autism spectrum disorders, conduct disorder, risk taking, and substance abuse. The present review evaluates what we currently know about the UF’s developmental trajectory and reviews the literature relating UF abnormalities to specific disorders. Additionally, we take a dimensional approach and critically examine symptoms and behavioral impairments that have been demonstrated to cluster with UF aberrations, in an effort to relate these impairments to our speculations regarding the functionality of the UF. We suggest that developmental disorders with core problems relating to memory retrieval, reward and valuation computation, and impulsive decision making may be linked to aberrations in uncinate microstructure.

White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

“…At this point, we might only speculate about relationships between tremor symptoms and WM clusters located in UF, ILF, and IFOF. All these bundles are involved in memory retrieval, reward processing, emotional regulation, impulsive responding, semantic language processing, attention, and reversal learning (Mandonnet, Nouet, Gatignol, Capelle, & Duffau, 2007; Martino & De Lucas, 2014; Olson, Von Der Heide, Alm, & Vyas, 2015), although orbitofrontal WM, part of both UF and ILF, was associated with the FTM score (Klein et al., 2011) and showed affected in previous ET study (Shin et al., 2008). Also, atrophy in frontal and temporal gray matter regions, which are interconnected by UF, was found related to the FTM scale (Bagepally et al., 2012) and an improvement of WM integrity within the ILF and IFOF was consistently reported among longitudinal DTI studies evaluating effects of physical training (Huang, Lu, Song, & Wang, 2015; Scholz et al., 2009), implying their involvement in motor functions.…”

White matter structure in the uncinate fasciculus: Implications for socio-affective deficits in Autism Spectrum Disorder

“…The uncinate fasciculus connects polar temporal areas, including the amygdala and hippocampus, to cortical regions such as orbitofrontal cortex (OFC) (Kier et al, 2004;Olson et al, 2015;Von der Heide et al, 2013). It therefore connects basic emotion processing areas with regions involved in higher order processing, including emotion regulation.…”

White matter microstructure in boys with persistent depressive disorder

“…Here, a negative relationship was found between children's self-reported depressive symptoms and FA. The UNC is the main tract connecting the prefrontal cortex with limbic structures including the amygdala and hippocampus (Catani, Howard, Pajevic, & Jones, 2002) and is thought to support emotion regulation, reversal learning, long-term memory retrieval and reward processing (Olson et al, 2015). All of these have been found to function atypically in patients with MDD (e.g.…”

“…While Huang et al (2011) did not find correlations with symptoms, other studies have found associations between FA in the uncinate and trait anxiety in healthy individuals (Kim & Whalen, 2009;Montag, Reuter, Weber, Markett, & Schoene-Bake, 2012); thus it is not clear whether lower FA precedes symptom onset or simply reflects symptom severity. Although the function of the uncinate is still largely unknown several previous studies have implicated its role in reversal learning, reward processing and long-term memory retrieval (Olson et al, 2015). The latter two are often impaired in MDD suggesting that white matter microstructure in the uncinate may be altered.…”

“…However, regional differences have been observed with fibres connecting frontal and temporal cortices (Colby, Van Horn, & Sowell, 2011;Lebel & Beaulieu, 2011;Tamnes et al, 2010) including the cingulum and uncinate fasciculi, which develop at a slower rate than some of the other fibres Olson, Von Der Heide, Alm, & Vyas, 2015;Westlye et al, 2010). Environmental stressor or genetic predisposition may differentially affect the development of white matter pathways and concomitant changes may relate to the development of depressive symptoms (Ladouceur, Peper, Crone, & Dahl, 2012).…”