Biology subjects

Meintjes, E. M.

Publications and source records attributed to Meintjes, E. M..

3 recordsLinked to original sources

bioRxiv2025

Evidence of functional connectivity disruptions between auditory and non-auditory regions in adolescents living with HIV

Children living with perinatally acquired HIV (CPHIV) demonstrate hearing impairments and language processing delays even in the presence of combination antiretroviral therapy (cART). Even though efficient processing of sound relies on the proper function of both the peripheral and central auditory auditory systems (PAS; CAS), investigations on the effect of HIV on the auditory system have predominantly focused on the PAS. Additionally, language processing requires the efficient interaction between CAS brain regions and non-auditory regions. Investigating the functional connectivity (FC) within the CAS and between the CAS and non-auditory regions may reveal the influence of HIV on regions involved in auditory function. Within a Bayesian stastical framework, we used resting-state functional magnetic resonance imaging (RS-fMRI) to map FC in the CAS as well as between CAS regions and non-auditory regions of 11-year-old CPHIV. Graph theory was used to investigate the regional effects of HIV on functional brain network properties. Finally we explored the relationships between FC and neurocognitive outcomes relating to auditory and language processing. We hypothesized that CPHIV would show disruptions in FC between CAS regions as well as between CAS and non-auditroy regions. Secondly, we hypothesized that in CPHIV, regional brain network properties would be altered compared to their uninfected peers (CHUU). Finally we hypothesized that FC and functional network regional outcomes would be related to neurocognitive outcomes. Our investigation revealed lower FC of the primary auditory cortex (PAC) in CPHIV as well as disruptions in FC between CAS regions (including the PAC) and non-auditry regions including hippocampal sub-regions, the lingual gyri and basal ganglia. Functional network analysis reavealed lower nodal degree and efficiency in CAS regions including the cochlear nucleus/superior olivary complex (CN/SOC) and the inferior colliculus (IC). We also report associations between the nodal efficiency of middle temporal and superior frontal regions and delayed recall, a neurocognitive marker of working memory, present in CHUU but not in CPHIV. Our results demonstrate FC alterations in the PAC and between CAS regions and non-auditory regions involved in limbic, visual and motor processing, as well as disruptions to the regional properties of the CAS regions as part of the functional brain network. These results provide insight into the state of the CAS FC in the presence of HIV and its possible role in the hearing and language impairments seen in this population.

neuroscience↗

bioRxiv2024

Distinct alterations in white matter properties and organization related to maternal treatment initiation in neonates exposed to HIV but uninfected

HIV exposed-uninfected (HEU) infants and children are at risk of developmental delays as compared to uninfected unexposed (HUU) populations. The effects of exposure to in utero HIV and ART regimens on the HEU the developing brain are not well understood. In a cohort of 2-week-old newborns, we used diffusion tensor imaging (DTI) tractography and graph theory to examine the influence of HIV and ART exposure in utero on neonate white matter integrity and organisation. The cohort included HEU infants born to mothers who started ART before conception (HEUpre) and after conception (HEUpost), as well as HUU infants from the same community. We investigated HIV exposure and ART duration group differences in DTI metrics (fractional anisotropy (FA) and mean diffusivity (MD)) and graph measures across white matter. We found increased MD in white matter connections involving the thalamus and limbic system in the HEUpre group compared to HUU. We further identified reduced nodal efficiency in the basal ganglia. Within the HEUpost group, we observed reduced FA in cortical-subcortical and cerebellar connections as well as decreased transitivity in the hindbrain area compared to HUU. Overall, our analysis demonstrated distinct alterations in white matter integrity related to the timing of maternal ART initiation that influence regional brain network properties.

neuroscience↗

bioRxiv2021

Distinctive neural correlates of phonological processing and reading impairment in fetal alcohol-exposed adolescents with and without facial dysmorphology

AbstractO_ST_ABSBackgroundC_ST_ABSPrenatal alcohol exposure (PAE) has been linked to atypical brain development and a wide range of cognitive and behavioral impairments, including poor reading performance in childhood and adolescence. However, little is known about how structural and/or functional teratogenesis in the brain mediate reading impairment in fetal alcohol spectrum disorders (FASD) and whether neural correlates of reading and phonological processing differ between FASD subtypes with different clinical presentations in facial morphology. MethodsThe current study utilized functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to characterize functional and structural mechanisms mediating reading deficits in 26 syndromal adolescents with PAE-related facial dysmorphology (i.e., fetal alcohol syndrome (FAS) or partial FAS (PFAS)) and 30 heavily exposed (HE) without this dysmorphology, in comparison with 19 typically developing controls. Importantly, the levels of PAE and reading ability were comparable between the FAS/PFAS and HE groups in the current study. ResultsCompared to the nonsyndromal HE and control groups, the syndromal adolescents showed greater activation in the right precentral gyrus during an fMRI phonological processing task and rightward lateralization in an important reading-related tract (inferior longitudinal fasciculus, ILF), suggesting an atypical reliance on the right hemisphere during reading. By contrast, in the HE group, better reading skills were associated with increased neural activation in the left angular gyrus (LAG) and higher fractional anisotropy in the white matter organization of the left ILF. However, the brain function-behavior relation was weaker in the HE than among the controls, suggesting less efficient function of the typical reading neural network that may contribute to the observed reading impairments. ConclusionsOur findings provide the first evidence for the distinctive functional and structural mechanisms underlying atypical reading and phonological processing in PAE adolescents with and without FAS facial dysmorphology. HighlightsO_LIPrenatal alcohol exposure is associated with altered neural reading networks C_LIO_LIFASD subtypes exhibit distinctive neural correlates of phonological processing C_LIO_LIGreater right-hemispheric reliance was observed in FASD with facial dysmorphology C_LIO_LINon-syndromal FASD showed deficits in the typical left-hemispheric reading network C_LI

neuroscience↗