Biology subjects

Abboud, S.

Publications and source records attributed to Abboud, S..

5 recordsLinked to original sources

bioRxiv2026

Early sensory deprivation drives local reorganization of sensory integration within a conserved global hierarchy

The human brain processes sensory information through a hierarchical system, from primary to higher-level regions, integrating inputs across modalities to support perception and cognition. While early sensory loss triggers widespread neuroplastic changes, its impact on integration across the cortical hierarchy remains unclear. Here, we examined the cortical reorganization of individuals with early blindness and deafness using a sensory integration framework that quantifies how brain regions prioritize different sensory inputs across the hierarchy. We found that early sensory deprivation drives highly localized reorganization adjacent to the deprived primary cortical areas: extrastriate cortex in early blindness and the superior temporal cortex in early deafness. These findings were further corroborated by analysis of the functional gradients, which found reorganization within these sensory regions. Notably, the hierarchy was largely preserved across groups. However, the sensory integration framework uniquely detected reorganization in language-related regions in deaf individuals with knowledge of a visual communication system known as cued speech. The specific differences between early deaf and hearing individuals remained restricted to superior temporal cortex. Together, our findings demonstrate that early sensory deprivation drives targeted reorganization adjacent to the affected primary sensory cortex, while preserving the overall hierarchy of cortical integration.

neuroscience↗

bioRxiv2025

Prior contact lens wear reduces susceptibility of the superficially-injured cornea to bacterial adhesion

Contact lens wear in humans and mice is consistently associated with asymptomatic corneal parainflammation. Here, we tested the hypothesis that the corneal response to lens wear alone can function to protect it against bacterial adhesion enabled by superficial injury. One eye only of mT/mG-LysMcre mice (cell membranes red; Lyz2+ cells green) wore a contact lens for 4-6 days. After lens removal, mice were anesthetized and both corneas superficially-injured before bacterial inoculation with either a mouse eyelid commensal (Macrococcus epidermidis) or a corneal pathogen (Pseudomonas aeruginosa). Inoculation was repeated hourly for 4 hours under anesthesia before euthanasia. Enucleated eyes were fixed overnight, and adherent bacteria visualized using a universal 16S rRNA-targeted FISH probe (M. epidermidis) or Blue Fluorescent Protein (P. aeruginosa). Confocal imaging and Imaris software were used to quantify bacterial adhesion and location in the epithelium, and also the number, location and morphology of Lyz2+ cells. For both commensal and P. aeruginosa, prior lens wear resulted in reduced adhesion to the superficially injured corneas ([~] 55% and [~] 45% respectively). In both instances this correlated with increased numbers of corneal Lyz2+ cells. Other details differed for the two bacterial types. For the commensal, prior lens wear resulted in bacteria penetrating deeper into the epithelium versus contralateral eyes, with Lyz2+ cells extending their processes further into the epithelium and localizing closer to the cornea surface. For P. aeruginosa, prior lens wear resulted in adherent bacteria closer to the cornea surface, and Lyz2+ cells moving further away from it. Moreover, while overall Lyz2+ cell sphericity increased for P. aeruginosa with prior lens wear versus contralateral eyes, it showed no overall change for the commensal. Lyz2+ cell volume in the central cornea was decreased for P. aeruginosa with prior lens wear but increased for the commensal. Thus, corneal responses to prior lens wear can quantitively reduce bacterial adhesion to superficially-injured corneas correlating with a Lyz2+ cell response for both a commensal and a pathogen, with differences in details for the two bacterial types. How continued lens wear supersedes this protective response to promote P. aeruginosa infection pathogenesis remains to be determined, as does the relationship to the Lyz2+ cell response. Author summaryContact lens wear induces asymptomatic corneal parainflammation in humans and mice involving multiple immune cell types. Here, we used a mouse model to test if previous lens wear would subsequently protect superficially-injured corneas against bacterial adhesion by either a murine commensal (Macrococcus epidermidis) or an opportunistic pathogen (Pseudomonas aeruginosa). Confocal imaging was used to quantify bacterial adhesion/location in addition to Lyz2+ immune cell numbers, location and morphology. Prior lens wear for 4-6 days, known to trigger corneal parainflammation, reduced the propensity for bacteria to adhere to corneas that were superficially-injured after the lens was removed: [~] 55% for the commensal and [~] 45% for P. aeruginosa versus contralateral eyes that had not worn a lens. In both instances this correlated with increased Lyz2+ immune cell numbers. However, differences were also noted, including that adherent commensals were found penetrating further into the epithelium while adherent P. aeruginosa remained close to the corneal surface. Lyz2+ cell location, sphericity and volume also differed for the two bacterial types. In sum, lens wear in the absence of bacterial inoculation can enable a response that protects the cornea against bacterial challenge after lens removal. How lens wear during inoculation overcomes this protective response to promote P. aeruginosa infection pathogenesis remains to be determined.

microbiology↗

bioRxiv2025

TRPV1 Defends the Healthy Murine Cornea against Staphylococcus aureus Adhesion Independently of Sensory Nerve Firing

PurposePreviously we showed that transient receptor potential ion channels TRPA1 and TRPV1 selectively protect the cornea against bacterial adhesion, with TRPA1 countering the Gram-negative pathogen Pseudomonas aeruginosa and TRPV1 countering environmental bacteria. Here, we explored parameters of this specificity using a Gram-positive pathogen Staphylococcus aureus. MethodsHealthy corneas of C57BL/6J wild-type (WT), TRPA1 (-/-) or TRPV1 (-/-) mice were challenged with S. aureus for 4 or 6 hours. Some experiments instead/also used resiniferatoxin (RTX) to deplete TRPV1-expressing nerves, JNJ-17203212 to selectively antagonize TRPV1, or the anesthetic bupivacaine to inhibit nerve firing. Adherent bacteria were quantified using FISH labeling (16S rRNA-targeted probe). Lyz2+, CD11c+ and CD45+ cells were visualized/quantified using hybrid mT/mG + LysMcre mice (red cell membranes; Lyz2+-GFP), CD11c+-YFP mice, and anti-CD45-antibody respectively. ResultsCorneas of TRPV1 (-/-) not TRPA1 (-/-) mice were found more susceptible to S. aureus adhesion compared to WT. Accordingly, either ablation of TRPV1-expressing nerves or TRPV1 antagonism increased adhesion. Defense against S. aureus adhesion did not depend on nerve firing. Despite having no significant impact on CD11c+ or Lyz2+ cell numbers, S. aureus challenge increased CD45+ cell counts, also dependent on TRPV1-expressing nerves, and it increased Lyz2+ cell sphericity and volume. ConclusionHealthy corneas utilize TRPV1 to protect against S. aureus adhesion independently of sensory nerve firing. This contrasts with defense against P. aeruginosa adhesion which requires TRPA1 and nerve firing. How the differential immune cell responses to these two pathogens relate to TRP-dependent defense against adhesion remains to be determined.

microbiology↗

bioRxiv2019

Semantic coding in the occipital cortex of early blind individuals

The visual cortex of early blind individuals is reorganized to support cognitive functions distinct from vision. Research suggests that one such prominent function is language. However, it is unknown whether the visual cortex of blind individuals codes for word meaning. We addressed this question by comparing neuronal activity evoked by a semantic decision task, using magnetoencephalography (MEG), between 12 early blind and 14 sighted participants otherwise comparable with regard to gender, age and education. We found that average brain responses to thousands of auditory word stimuli followed similar time courses in blind and sighted participants. However, in blind participants only, we found a sustained enhancement of activity in the visual cortex. Moreover, across the whole brain, we found an effect of semantic category from about 400 ms after word onset. Strikingly, in blind participants, semantic categories were discriminable starting 580 ms after word onset from signal captured by sensors sensitive to the visual cortex. We replicated the analyses in time windows locked to stimulus onset and behavioral response, using both classical hypothesis testing and machine learning for single-trial classification. Semantic decisions were well classified in all participants (AUC [~] 0.60), but generalization capacity across participants was found reduced in the blind group due to a larger variability of discriminative patterns. In conclusion, our findings suggest that brain plasticity reorganizes the semantic system of blind individuals, and extends semantic computation into the visual cortex.

neuroscience↗

bioRxiv2018

Distinctive interaction between cognitive networks and the visual cortex in early blind individuals

In early blind individuals, brain activation by a variety of non-perceptual cognitive tasks extends to the visual cortex, while in the sighted it is restricted to supramodal association areas. We hypothesized that such activation results from the integration of different sectors of the visual cortex into typical task-dependent networks. We tested this hypothesis with fMRI in blind and sighted subjects using tasks assessing speech comprehension, incidental long-term memory and both verbal and non-verbal executive control, in addition to collecting resting-state data. All tasks activated the visual cortex in blind relative to sighted subjects, which enabled its segmentation according to task sensitivity. We then assessed the unique brain-scale functional connectivity of the segmented areas during resting state. Language-related seeds were preferentially connected to frontal and temporal language areas; the seed derived from the executive task was connected to the right dorsal frontoparietal executive network; the memory-related seed was uniquely connected to mesial frontoparietal areas involved in episodic memory retrieval. Thus, using a broad set of language, executive, and memory tasks in the same subjects, combined with resting state connectivity, we demonstrate the selective integration of different patches of the visual cortex into brain-scale networks with distinct localization, lateralization, and functional roles.

neuroscience↗