Publication Type: Individual Poster
Abstract: Background and goals. Infants exhibit spontaneous eye blinks (SB) infrequently compared to adults. Investigations using healthy adults, clinical populations, and neuropharmacological manipulations in non-human primates have shown that SB rates can be manipulated, patterns of SB vary for some disorders, and SB mechanisms involve central dopamine systems. Little is known about SB in infants. Our goals include investigating the development of SB and behavioral systems linked to SB. Here, we focused on relationships between SB and temperament, body movement and cardiac activity.

Methods. 22 healthy, term infants (11 F) were observed during baseline (3-5 min) then during either moving objects (N=11) or a social condition (N=11)(5-6 min). Previous work suggests that the inter-blink-interval (IBI) would change in opposite directions for these stimuli. Temperament was assessed by the IBQ-R and lab measurements (one measurement examined approach behavior).

Results. IBI was not related to: feeding method, time of day, time since last feeding, body weight. Individual differences in IBI were wide: 7-83 sec (baseline) M=24 (SD=16). IBI increased from baseline (21-28 sec; p=.02) and males had longer IBI (p=.03), but IBI did not differ by stimulus. Body movement (p=.01) and heart rate (p<.001) decreased across phase. However, changes in body movement and heart rate were unrelated to the change in IBI. MANOVA was used to test the relationships between infant characteristics (sex), temperament (approach, IBQ-R factors), infant activity (body movement) and IBI change across phase. Results confirmed effects for sex and phase, and indicated that infants’ approach and the IBQ-R’s duration of orienting interacted with phase in their relationship to IBI.

Conclusions. Like adults, infants exhibit wide individual differences in IBI and IBI can be manipulated. Increased attention to moving objects and a social stimulus increased IBI, yet this change was not explained by somatic and cardiac variables. The change in IBI may be related to features of temperament as measured by variables of approach and duration of orienting. Unlike previous work, sex differences in IBI were found. Additional preliminary analyses suggested that increases in sustained gaze might be linked to the changes in IBI. Therefore, SB in infants was related to stable infant characteristics as well as their responses to the environment. SB regulation is complex, yet understanding the expression, mechanisms and functional correlates of SB could reveal insights into the development and integration of attention, motivation and temperament.
(Supported by NIH EY16238 to LFB)