Perineuronal nets are extracellular matrix structures comprised of chondroitin and dermatan sulfate-glycosaminoglycans (CS/DS-GAGs). Histological imaging of brain PNNs is achieved using Wisteria floribunda agglutinin (WFA) labeling of PNN CS/DS-GAGs, while composition can be determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Although these methods are used to determine PNN CS/DS-GAG abundance and composition, it’s unknown whether brain fixation or processing influence these outcomes. We first explored whether tissue processing, using cryosectioning (CRYO) or paraffin embedding (PE), influence PNN analyses. Ten mice were perfused with PBS and post-fixed in 4% paraformaldehyde (PFA). Brains were cut sagittal, and one hemisphere was prepared as floating tissues (CRYO) and the second hemisphere was processed as direct mounted tissues (PE). Histochemical analyses show a 78.9% reduction in hippocampal WFA+ PNNs in the PE processed hemisphere compared to CRYO processed side. LC-MS/MS analysis of hippocampal CS/DS isomers also showed differences between each method. In a second cohort of mice, we determined that fixative (4% PFA vs 10% formalin) did not influence hippocampal WFA or CS/DS isomers between groups, suggesting tissue processing (not fixative) influences PNN analyses. We then explored whether we could correct for these CS/DS baseline differences. By comparing CS/DS isomers isolated from CRYO vs PE processed tissues within each mouse, we discovered reproducible correction factors for each isomer. Adjusting the CRYO group using these factors normalizes baseline compositional differences between CRYO and PF groups. To determine translational relevance, we compared hippocampal CS/DS isomers between three CRYO vs PE prepared non-human primate (M. nemestrina) tissues and observe similar baseline CS/DS differences. Adjusting the CRYO prepared group using corrections factors normalizes the baseline composition. These results provide strong, translational evidence that tissue processing greatly influences both PNN glycan histology and composition analyses, and that corrections must be made to account for baseline differences before comparing groups.

Adolescence is a critical stage of development, a time in which social relations are pivotal to feelings of connectedness, belongingness, and wellbeing. Amidst the rise in usage of widespread social media platforms, adolescents have begun to seek out online-only friendships (OOFs), prompting our lab to explore the prevalence and quality of these social connections. We first gathered data from adolescents (n = 5756, ages 10-18) in Peru in 2020, during the COVID-19 lockdown. In 2023, we repeated and refined our prior analyses after gathering data from adolescents in Bolivia (n = 1071) and Uruguay (n = 647). We administered a Qualtrics survey asking participants to self-report on the number and perceived quality of OOFs and IPFs (in-person friendships), using the Network of Relationships Inventory (Furman and Buhmester, 1985). I served as a Research Assistant (RA) for the interACT Lab. I reviewed the literature on online friendships, performed data cleanup, and assisted on statistical analyses of our data. Given the lack of prior research on the topic, our lab sought to explore the quality of online friendships in order to provide a foundation for future investigations. Currently, our lab is analyzing the quality of IPFs vs. OOFs on the basis of self-reported levels of support, closeness, trust, and similar-interests. 79.8% of adolescents in our sample have OOFs. In addition, preliminary findings indicate that IPFs have more negative qualities than OOFs, and that OOFs have more negative qualities than IPFs . This work is important because not only does it examine adolescent technology usage in regard to social connectivity, but it also presents findings from the Global South, which is often underrepresented in psychology research. Our findings provide an understanding of the benefits and downsides of engaging in online-only friendships for adolescents in South America, a region that is too often underrepresented in psychology research.