Dataset Information

Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.

ABSTRACT: Many of the behavioral capacities that distinguish humans from other primates rely on fronto-parietal circuits. The superior longitudinal fasciculus (SLF) is the primary white matter tract connecting lateral frontal with lateral parietal regions; it is distinct from the arcuate fasciculus, which interconnects the frontal and temporal lobes. Here we report a direct, quantitative comparison of SLF connectivity using virtual in vivo dissection of the SLF in chimpanzees and humans. SLF I, the superior-most branch of the SLF, showed similar patterns of connectivity between humans and chimpanzees, and was proportionally volumetrically larger in chimpanzees. SLF II, the middle branch, and SLF III, the inferior-most branch, showed species differences in frontal connectivity. In humans, SLF II showed greater connectivity with dorsolateral prefrontal cortex, whereas in chimps SLF II showed greater connectivity with the inferior frontal gyrus. SLF III was right-lateralized and proportionally volumetrically larger in humans, and human SLF III showed relatively reduced connectivity with dorsal premotor cortex and greater extension into the anterior inferior frontal gyrus, especially in the right hemisphere. These results have implications for the evolution of fronto-parietal functions including spatial attention to observed actions, social learning, and tool use, and are in line with previous research suggesting a unique role for the right anterior inferior frontal gyrus in the evolution of human fronto-parietal network architecture.

SUBMITTER: Hecht EE

PROVIDER: S-EPMC4324003 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.

Hecht Erin E EE Gutman David A DA Bradley Bruce A BA Preuss Todd M TM Stout Dietrich D

NeuroImage 20141220

Many of the behavioral capacities that distinguish humans from other primates rely on fronto-parietal circuits. The superior longitudinal fasciculus (SLF) is the primary white matter tract connecting lateral frontal with lateral parietal regions; it is distinct from the arcuate fasciculus, which interconnects the frontal and temporal lobes. Here we report a direct, quantitative comparison of SLF connectivity using virtual in vivo dissection of the SLF in chimpanzees and humans. SLF I, the superi ...[more]

PMID: 25534109

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Project description:AimTo understand the relationship between cognition and white-matter structure in adolescents born preterm without obvious brain injury.MethodsThirty-two adolescents from a longitudinal study of child development were selected according to risk of developmental disorders at birth (born at term: eight males, five females; median age 16y 1mo, interquartile range 10mo; low risk preterm: four males, five females, median age 16y, range 4mo; high risk preterm: three males, seven females, median age 16y 2mo, range 1y 2mo) and reading ability (good: three males, eight females, median age 16y, range 7mo; average: six males, three females, median age 16y 10mo, range 1y; poor: six males, six females, median age 16y, range 6mo). Preterm birth was defined as a gestational age of 36 weeks or less and a birthweight of 1600g or less. All participants had normal clinical neuroimaging findings. We examined fractional anisotropy, radial diffusivity, and volume of three major white-matter fasciculi. The relationship between structural measures and birth risk, hemisphere, and cognitive ability (attention, lexical and sublexical decoding, auditory phonological awareness, and processing speed) were analysed using mixed-model regression.ResultsLeft-hemisphere superior longitudinal fasciculus (SLF) fractional anisotropy and radial diffusivity were linked to reading-related skills (fractional anisotropy vs letter-word identification, r((30))=-0.37, p<0.05; fractional anisotropy vs phoneme reversal, r((30))=-0.34, p=0.05; radial diffusivity vs letter-word identification, r((30))=0.31, p<0.10; radial diffusivity vs phoneme reversal, r((30))=0.40, p<0.05), whereas right-hemisphere SLF fractional anisotropy was related to attention skills (fractional anisotropy vs inattentiveness, r((30))=-0.38, p<0.05). SLF volume decreased as these skills declined for adolescents born preterm (volume vs phoneme reversal, r((17))=0.58, p<0.01; volume vs inattentiveness, r((17))=-0.69, p<0.01), but not for those born at term.InterpretationThe relationship between cognitive skills and SLF volume suggests that in adolescents born preterm, cryptic white-matter injury may exist, possibly related to oligodendrocyte or axonal loss, despite normal clinical neuroimaging.

Project description:BackgroundWearable devices have been found effective in training ankle control in patients with neurological diseases. However, the neural mechanisms associated with using wearable devices for ankle training remain largely unexplored. This study aimed to investigate the ankle tracking performance and brain white matter changes associated with ankle tracking learning using a wearable-device system and the behavior-brain structure relationships in middle-aged and older adults.MethodsTwenty-six middle-aged and older adults (48-75 years) participated in this study. Participants underwent 5-day ankle tracking learning with their non-dominant foot using a custom-built ankle tracking system equipped with a wearable sensor and a sensor-computer interface for real-time visual feedback and data acquisition. Repeated and random sequences of target tracking trajectories were both used for learning and testing. Ankle tracking performance, calculated as the root-mean-squared-error (RMSE) between the target and actual ankle trajectories, and brain diffusion spectrum MR images were acquired at baseline and retention tests. The general fractional anisotropy (GFA) values of eight brain white matter tracts of interest were calculated to indicate their integrity. Two-way (Sex × Time) mixed repeated measures ANOVA procedures were used to investigate Sex and Time effects on RMSE and GFA. Correlations between changes in RMSE and those in GFA were analyzed, controlling for age and sex.ResultsAfter learning, both male and female participants reduced the RMSE of tracking repeated and random sequences (both p < 0.001). Among the eight fiber tracts, the right superior longitudinal fasciculus II (R SLF II) was the only one which showed both increased GFA (p = 0.039) after learning and predictive power of reductions in RMSE for random sequence tracking with its changes in GFA [β = 0.514, R2 change = 0.259, p = 0.008].ConclusionsOur findings implied that interactive tracking movement learning using wearable sensors may place high demands on the attention, sensory feedback integration, and sensorimotor transformation functions of the brain. Therefore, the SLF II, which is known to perform these brain functions, showed corresponding neural plasticity after such learning, and its plasticity also predicted the behavioral gains. The SLF II appears to be a very important anatomical neural correlate involved in such learning paradigms.

Dataset Information

Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.

Publications

Virtual dissection and comparative connectivity of the superior longitudinal fasciculus in chimpanzees and humans.

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