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Lauren L. Emberson
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Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2020) 32 (3): 508–514.
Published: 01 March 2020
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View articletitled, A Computational Role for Top–Down Modulation from Frontal Cortex in Infancy
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for article titled, A Computational Role for Top–Down Modulation from Frontal Cortex in Infancy
Recent findings have shown that full-term infants engage in top–down sensory prediction, and these predictions are impaired as a result of premature birth. Here, we use an associative learning model to uncover the neuroanatomical origins and computational nature of this top–down signal. Infants were exposed to a probabilistic audiovisual association. We find that both groups (full term, preterm) have a comparable stimulus-related response in sensory and frontal lobes and track prediction error in their frontal lobes. However, preterm infants differ from their full-term peers in weaker tracking of prediction error in sensory regions. We infer that top–down signals from the frontal lobe to the sensory regions carry information about prediction error. Using computational learning models and comparing neuroimaging results from full-term and preterm infants, we have uncovered the computational content of top–down signals in young infants when they are engaged in a probabilistic associative learning.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2017) 29 (12): 1963–1976.
Published: 01 December 2017
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View articletitled, Neural Signatures of Spatial Statistical Learning: Characterizing the Extraction of Structure from Complex Visual Scenes
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for article titled, Neural Signatures of Spatial Statistical Learning: Characterizing the Extraction of Structure from Complex Visual Scenes
Behavioral evidence has shown that humans automatically develop internal representations adapted to the temporal and spatial statistics of the environment. Building on prior fMRI studies that have focused on statistical learning of temporal sequences, we investigated the neural substrates and mechanisms underlying statistical learning from scenes with a structured spatial layout. Our goals were twofold: (1) to determine discrete brain regions in which degree of learning (i.e., behavioral performance) was a significant predictor of neural activity during acquisition of spatial regularities and (2) to examine how connectivity between this set of areas and the rest of the brain changed over the course of learning. Univariate activity analyses indicated a diffuse set of dorsal striatal and occipitoparietal activations correlated with individual differences in participants' ability to acquire the underlying spatial structure of the scenes. In addition, bilateral medial-temporal activation was linked to participants' behavioral performance, suggesting that spatial statistical learning recruits additional resources from the limbic system. Connectivity analyses examined, across the time course of learning, psychophysiological interactions with peak regions defined by the initial univariate analysis. Generally, we find that task-based connectivity with these regions was significantly greater in early relative to later periods of learning. Moreover, in certain cases, decreased task-based connectivity between time points was predicted by overall posttest performance. Results suggest a narrowing mechanism whereby the brain, confronted with a novel structured environment, initially boosts overall functional integration and then reduces interregional coupling over time.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2012) 24 (10): 2030–2042.
Published: 01 October 2012
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View articletitled, Learning to Sample: Eye Tracking and fMRI Indices of Changes in Object Perception
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for article titled, Learning to Sample: Eye Tracking and fMRI Indices of Changes in Object Perception
We used an fMRI/eye-tracking approach to examine the mechanisms involved in learning to segment a novel, occluded object in a scene. Previous research has suggested a role for effective visual sampling and prior experience in the development of mature object perception. However, it remains unclear how the naive system integrates across variable sampled experiences to induce perceptual change. We generated a Target Scene in which a novel occluded Target Object could be perceived as either “disconnected” or “complete.” We presented one group of participants with this scene in alternating sequence with variable visual experience: three Paired Scenes consisting of the same Target Object in variable rotations and states of occlusion. A second control group was presented with similar Paired Scenes that did not incorporate the Target Object. We found that, relative to the Control condition, participants in the Training condition were significantly more likely to change their percept from “disconnected” to “connected,” as indexed by pretraining and posttraining test performance. In addition, gaze patterns during Target Scene inspection differed as a function of variable object exposure. We found increased looking to the Target Object in the Training compared with the Control condition. This pattern was not restricted to participants who changed their initial “disconnected” object percept. Neuroimaging data suggest an involvement of the hippocampus and BG, as well as visual cortical and fronto-parietal regions, in using ongoing regular experience to enable changes in amodal completion.