The development of social-visual attention and brain attentional networks in rhesus macaques Restricted; Files Only

Abstract

This study investigated the developmental trajectories of social-visual attention and the dorsal and ventral brain attentional networks using non-human primates (NHP) as a translational model. This study had two main aims. The first aim investigated the development of the social-visual attention skills of infant macaques, and the influence of social rank. The second aim investigated the development of cortical areas within the dorsal and ventral brain attentional networks in infant macaques and the influence of social rank.

Seventeen infant macaques, 9 high ranking and 8 low ranking, underwent eye-tracking procedures at 1, 2, 3, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, and 23 weeks of age. They observed short videos of dam-infant interactions from which specific social episodes were identified: mutual gaze between infants and dams or other peers, shared attention between infants and dams, and entrance of a new monkey. Measures of social-visual development included fixations to regions of interest (dams eye/head, infant eye/head) and completion of saccades between relevant stimuli. Longitudinal brain structural MRI scans were acquired at 2, 4, 6, 8, 12, and 24 weeks of age. Volumetric changes were examined within the primary visual cortex (V1), extrastriate area (V3), cortical areas within the dorsal attention network (DAN), including the lateral intraparietal area (LIP) and frontal eye field (FEF), and within the ventral attention network (VAN), including the temporoparietal junction (TPJ) and the ventrolateral prefrontal cortex (vlPFC).

The results indicate age-specific variations in the development of social-visual attention in infant macaques that were not impacted by social rank. Attention to the dam remained relatively higher than attention to the infant in both mutual gaze and shared attention episodes. The percent saccades completed increased with age in shared attention episodes but decreased in mutual gaze episodes. In addition, volumes of both the DAN and VAN pathways increased in the first 6 months of age. The most posterior cortical areas of the pathways (LIP and TPJ) appear to mature relatively faster than the most anterior cortical areas in the prefrontal cortex (FEF and vlPFC). Social rank impacted the growth of V1 and cortical areas within the VAN. Correlations between brain and behavior data indicate that the development of early cortical visual and attentional areas may impact the development of social-visual attention at specific timepoints.

These findings suggest that there are robust developmental changes in social-visual attention skills and brain attention networks of infant macaques during the first 24 weeks of life, but social rank plays a relatively minimal role in these changes. A deeper understanding of this typical neurobehavioral development will help identify early social and neural markers that are the sources of atypical social and brain development in humans.

Table of Contents

Introduction................................................................................................................................. 1

Methods........................................................................................................................................13

Subjects and Housing.....................................................................................................................13

Aim 1 Methods: Social-Visual Attention.......................................................................................... 14

Data Acquisition................................................................................................................ ............14

Stimuli......................................................................................................................................... 15

Data Processing............................................................................................................................ 16

Statistical Analysis........................................................................................................................ 17

Aim 2 Methods: Brain Attentional Networks............................................................................ ...... .19

Data Acquisition ........................................................................................................................... 19

Data Processing............................................................................................................................ 19

Behavior and Brain Correlation...................................................................................................... 21

Results......................................................................................................................................... 21

Aim 1 Results: Eye-tracking Data................................................................................................... 21

Fixations and Saccades to Mutual Gaze Social Episodes................................................................... 21

Fixations and Saccades to Shared Attention Social Episodes............................................................ 22

Summary..................................................................................................................................... 23

Aim 2 Results: sMRI Data............................................................................................................. 24

Early Cortical Areas...................................................................................................................... 24

DAN Areas................................................................................................................................... 25

VAN Areas................................................................................................................................... 26

Summary..................................................................................................................................... 27

Behavior and Brain Correlation Data.................................................................................. ........... 28

Discussion................................................................................................................................... 30

Figures........................................................................................................................................ 45

References................................................................................................................................... 73

About this Honors Thesis

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School	Emory College
Department	Neuroscience and Behavioral Biology
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Biology, Neuroscience
Keyword	Social-Visual Attention Development Rhesus Macaque Cortical Development
Committee Chair / Thesis Advisor	Bachevalier, Jocelyne, Emory University
Committee Members	Sanchez, Mar, Emory University Kazama, Andy, Emory University

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