Author(s): JIANG, L., CAO, Y., ZHANG, D., ZHANG, K., Institution: SOUTHEAST UNIVERSITY, Country: CHINA, Abstract-ID: 1478

Introduction
Smartphone use has become a dominant lifestyle behavior among Z-generation college students, raising growing concerns about its potential impact on emotional well-being and brain function. Although previous studies have linked excessive smartphone use to negative affect, the underlying neural correlates remain unclear, particularly regarding how smartphone use may relate to alterations in resting-state brain function. The present study aimed to examine the associations between weekly smartphone use time, resting-state functional activity, and emotional states, including positive affect (PA) and negative affect (NA), in college students.

Methods
Fifty college students were recruited and classified into low- and high-smartphone use groups based on weekly usage time, with no significant differences in age or sex between groups. Weekly smartphone use time was obtained from the built-in screen time statistics function of participants' mobile phones and averaged across the past week. Participants completed the PANAS to assess positive affect (PA) and negative affect (NA). Resting-state fMRI data were collected and preprocessed, and fALFF values were computed. The hippocampus and DLPFC were defined as regions of interest using the AAL atlas due to their roles in cognition, memory, and emotion regulation. One-way ANOVA was conducted to compare age, fALFF, and emotional measures between groups. Pearson correlation analyses were further performed to examine associations between smartphone use time, brain activity, and affective measures.

Results
(1) Significant group effects were observed in resting-state fALFF within bilateral hippocampus and DLPFC. The high-use group showed higher fALFF in the left hippocampus (F(1, 48) = 7.92, p = .007, eta_p2 = .142), right hippocampus (F(1, 48) = 4.21, p = .046, eta_p2 = .081), left DLPFC (F(1, 48) = 8.08, p = .007, eta_p2 = .144), and right DLPFC (F(1, 48) = 4.22, p = .046, eta_p2 = .081).
(2) The high-use group reported significantly lower positive affect (PA), F(1, 48) = 5.84, p = .020, eta_p2 = .109, while negative affect (NA) showed a marginal group difference, F(1, 48) = 3.85, p = .056, eta_p2 = .074.
(3) In terms of emotional measures, smartphone use was positively associated with NA (r = .378, p = .007), while No significant association was found between smartphone use and PA, despite a slight negative trend.

Conclusion
The high-use group showed elevated resting-state fALFF in bilateral hippocampus and DLPFC, accompanied by lower positive affect (PA). Correlation analyses further revealed that smartphone use time was positively associated with hippocampal fALFF and NA, but not with PA or DLPFC activity. Given that hippocampal plasticity is known to be sensitive to behavioral modulation, including aerobic exercise, future studies may examine whether structured physical activity programs are associated with improvements in cognitive and emotional functioning among college students.