Poster #11 - Selective Repetition Suppression Indexes Cortical Fine-Tuning to Human Faces at the age of 7 Months

• In Event: Poster Session 03

Abstract

Background: The development of the capacities to detect and recognize human faces has been approached by theoretical frameworks stressing either genetically driven maturation (Farah et al., 2000) or interactive, activity-dependent, specialization (Johnson, 2011). While these views are compatible with the early emerging sensitivity to faces found in infant event-related potentials (ERPs; Conte et al., 2020), they differ with regards to the degree of fine-tuning and recruitment of neural resources involved in face processing. In this study, we probed the fine-tuning and recruitment of neural assemblies through stimulus-specific repetition effects induced by human and non-human face stimuli. The maturational model suggests early categorical tuning to human faces which predicts a) repetition suppression of face-elicited ERPs and b) release from this suppression when human faces are interleaved with control stimuli. The activity-dependent framework suggests the involvement of increased neural assemblies in encoding of face stimuli which, in turn, predicts repetition enhancement of face-elicited ERPs in sequences consisting uniformly of human faces.

Methods: ERPs were recorded from seven-month-old infants (N=49) who were presented with human and cat faces (as control stimuli). We focused on the N290 response, peaking at around 290 milliseconds after face onset, which is typically amplified for faces as opposed to control stimuli (Conte et al., 2020). We used a repetition paradigm where human or cat faces were either alternated or presented in blocks consisting uniformly of human or cat faces. If repetition suppression of the N290 would be found in uniform vs. alternating sequences, we could suggest that the human faces elicited activity in cortical areas that are selectively tuned to human faces. Repetition enhancement would, in contrast, suggest the recruitment of increased neural resources involved in the encoding of faces (Nordt et al., 2016). The human and cat faces, 500 ms in duration, were presented at the rate of 1 Hz. For validating the method, we collected ERP data from adult participants (N=21) using same stimulus material to elicit the face-related N170 response.

Results: Prominent occipitotemporal N290 and N170 were elicited by both human and cat faces in infant and adult participants, respectively. The peak-to-peak amplitude of the infant N290-P100 response was found to indicate stimulus-specific repetition effects, where the response amplitude was suppressed for repeating vs. cat-interleaved human faces. This stimulus-specific repetition effect was found also in the adult N170 (cf., Schweinberger and Neumann, 2016) along with increased N170 to human faces vs. control stimuli. In infant participants, a larger N290-P100 amplitude was found in the cat vs. human face condition.

Conclusions: The stimulus-specific repetition effects suggest that human faces elicited activity in neural assemblies that were not activated by cat faces in both infants and adults. These results, thus, evidence for cortical fine-tuning to human faces by the age of seven months which is line with the maturational model of the development of face processing. Increased N290-P100 amplitude was found in response to cat faces, presumably reflecting stimulus novelty in infant participants. No repetition enhancement of cortical responses to human faces was found.

Authors

• Santeri Yrttiaho, Tampereen yliopisto (Tay)
  Presenting Author

• Anneli Kylliäinen, Tampere University

• Tiina Parviainen, University of Jyväskylä

• Mikko Peltola