2014 — 2017 |
Mcpeek, Robert M |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Cortical and Subcortical Control of Saccades @ State College of Optometry
DESCRIPTION (provided by applicant): Rapid and accurate saccadic eye movements are crucial for vision. Since real-world scenes are often crowded with many objects, a fundamental requirement for saccades is the serial selection of single targets from a field of multiple potentil targets. Saccade target selection is subserved by a network of cortical and subcortical brain areas, but we still have little idea of how activity across these areas is coordinated. This projec investigates the interactions among the superior colliculus (SC), the frontal eye field (FEF), and the dorsolateral prefrontal cortex (dlPFC). The SC is regarded as the gateway for eye-movement commands from cortex to reach the brainstem, but perturbations in SC activity do not just affect the execution of saccades; they also influence the selection of eye-movement targets. This raises a key question: Does the SC simply act as a final selection stage before transmitting saccade commands downstream, or does SC activity influence saccadic decision-making in cortex? To answer this, we will simultaneously record isolated neurons and local field potentials from SC and FEF, and apply advanced analysis techniques to reveal the interactions and likely flow of information between these two areas. Next, we will perturb activity in the SC by temporarily inactivating a portion of it, and will determine whether and how selection-related activity in FEF is altered. We will also investigate how frontal cortex influences selection in the SC. Specifically, frontal area dlPFC is thought to be particularly important for selection based on abstract rules or internal goals. We will test this idea and investigate dlPFC's influence on the SC by analyzing simultaneously-recorded activity in the two areas during performance of rule-governed and salience-based selection tasks. Finally, to test for a causal link with dlPFC, we will record behavior and SC activity while dlPFC is temporarily inactivated. The results will not only provide new information about the functional architecture of saccadic decision-making; they will also lead toward a better understanding of how cortical and subcortical brain areas interact in performance of a cognitive task.
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0.967 |
2019 — 2021 |
Mcpeek, Robert M Zelinsky, Gregory J (co-PI) [⬀] |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Saccade Target Selection in Naturalistic Visual Search @ State College of Optometry
Project Summary Understanding how we select targets for saccadic eye movements is a basic research question of far-reaching importance. These rapid eye movements allow the fovea to fixate objects of interest, and we typically make more than 170,000 saccades each day. Saccades are essential for efficient visual perception and action: from reading to cooking to driving, most common behaviors heavily engage the saccadic system, and a dysfunctional mechanism for selecting saccade targets would impair performance in all of these everyday activities. The superior colliculus (SC), a key midbrain structure responsible for controlling saccades, is comprised of two subdivisions: the superficial layers (SCs), which respond predominantly to visual stimuli, and the intermediate layers (SCi), which can show both visual and saccade-related responses. Despite its importance, we still know little about how the SC selects saccade targets in realistic conditions. This study will address this critical gap in our knowledge. A major obstacle to progress in this area has been the complexity of analyzing neural responses under naturalistic conditions, and tackling this problem requires a model that can provide testable predictions of neural responses in naturalistic conditions. We will use a state-of-the-art neural model, MASC (Model of Attention in the Superior Colliculus), which incorporates constraints based on SC anatomy and physiology, and does a superior job of predicting saccade endpoints and scanpaths in a variety of search and free-viewing tasks. In conjunction with neural recordings, we will elucidate how superficial- and intermediate-layer SC neurons differ in their integration of activity related to salience, relevance, inhibitory tagging, and movement selection during multi-saccade visual search. In addition, we will test the contributions of the frontal eye field, a cortical area providing input to the SC, to these search-related signals in the SC.
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0.967 |