Interrogating the infant mind with fMRI

Abstract

My dissertation research focused on uncovering the functional organization of higher-level perceptual and cognitive processes in infants’ brains. For two decades scientists have attempted to use functional magnetic resonance imaging (fMRI) to study infant perceptual and cognitive function. However, it remains unclear whether the basic structure of adult cortical organization is present in young infants. Chapter 2 describes innovations to improve infant fMRI techniques including the design of MRI-safe infant headphones and a size-adaptive 32-channel infant head coil. These improvements resulted in higher quality data that were less corrupted by motion artifacts. Previous fMRI studies of higher-level visual cortex in awake infants observed preferential responses to faces [5,6] and scenes [5]. In Chapter 3 I show that with increased power, we can detect infants’ (2-9 months) face-selective responses in the fusiform face area (FFA), scene-selective responses in the parahippocampal place area (PPA), and body-selective responses in the extrastriate body area (EBA) and that these responses cannot be easily explained by the low-level visual features present in the stimuli. With these same data, I test different theories of cortical development and find evidence that face-selective responses in infant FFA, superior temporal sulcus (STS), and medial prefrontal cortex (MPFC) emerge in parallel indicating that as early as infants can detect and perceive a face, they also attribute social meaning to that face. My thesis then interrogates the origin of human-unique music and speech perception. In Chapter 5 I show that infants’ (2-11 weeks) cortical response to music and speech cannot be explained by the spectrotemporal modulation statistics of those two auditory categories. In sum, my dissertation research finds that signatures of cortical organization of higher-level perceptual processing in adults are already present in young infants.