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Infants sex affects neural responses to affective touch in early infancy
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  • isabella lucia mariani wigley,
  • Malin Björnsdotter,
  • Noora Scheinin,
  • Harri Merisaari,
  • Jani Saunavaara,
  • Riitta Parkkola,
  • Sabrina Bonichini,
  • Rosario Montirosso,
  • Linnea Karlsson,
  • Hasse Karlsson,
  • Jetro Tuulari
isabella lucia mariani wigley
University of Padua

Corresponding Author:[email protected]

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Malin Björnsdotter
Sahlgrenska University Hospital
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Noora Scheinin
University of Turku
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Harri Merisaari
University of Turku
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Jani Saunavaara
University of Turku
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Riitta Parkkola
University of Turku
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Sabrina Bonichini
University of Padua
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Rosario Montirosso
IRCCS Medea
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Linnea Karlsson
University of Turku
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Hasse Karlsson
University of Turku
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Jetro Tuulari
University of Turku
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Abstract

Social touch is closely related to the establishment and maintenance of social bonds in humans and the sensory brain circuit for gentle brushing is already active soon after birth. Brain development is known to be sexually dimorphic, but the potential effect of sex on brain activation to gentle touch remains unknown. Here, we examined brain activation to gentle skin stroking, a tactile stimulation that resembles affective/social touch, in term-born neonates. Eighteen infants aged 11-36 days, recruited from the FinnBrain Birth Cohort Study, were included in the study. During natural sleep, soft brush strokes were applied to the skin of the right leg during functional magnetic resonance imaging (fMRI) at 3cm/s velocity. We examined potential differences in brain activation between males (n = 10) and females (n = 8) and found that females had larger blood oxygenation level dependent (BOLD) responses (brushing vs. rest) in bilateral orbitofrontal cortex (OFC), right ventral striatum and bilateral inferior striatum, pons and cerebellum compared to males. Moreover, the psychophysiological interactions (PPI) analysis, setting left and right OFC as seed regions, revealed significant differences between males and females. Females exhibited stronger PPI connectivity between the left OFC and posterior cingulate/cuneus. Our work suggests that social touch neural responses are different in male and female neonates, which may have major ramifications for later brain, cognitive and social development. Finally, many of the sexually dimorphic brain responses were subcortical, not captured by surface-based neuroimaging, indicating that fMRI will be a relevant technique for future studies.