Research Overview

We study mid- and high-level visual processing, specifically links between visual perception, eye movements and neural circuits. We use neurophysiological, psychophysical and computational approaches, combined to improve our understanding of the cortical substrates of natural visually guided behavior (‘natural vision’). Our neurophysiological experiments make extensive use of linear and nonlinear systems identification techniques to characterize single neuron selectivity in striate and extrastriate visual cortex.

In humans, we have developed modern gaze-contingent psychophysical methods in order to investigate the reference frame or coordinate system used to encoded and sustain spatial attention across saccadic eye movements. This work lies at the intersection of visual attention, working-memory and oculomotor behavior and is intended to explore how all three of these subsystems interact during naturalistic behaviors that depend on eye movements.

The Mazer lab was part of the Department of Cell Biology & Neuroscience, which merged in 2019 with the Department of Microbiology & Immunology”, at Montana State University in Bozeman, MT, USA. We are also members of the NSF EPSCoR-funded Attention Consortium, a collaborative team of researchers at Montana State, Dartmouth, Brown and the University of Nevada Reno, all studying the neural basis of attention.

Projects

Attentional modulation of extrastriate cortex

Several ongoing projects in the lab are investigating how top-down attention can alter neuronal selectivity in extrastriate visual cortex. In particular, we are interested in understanding how single neurons in area V4 change their tuning profiles during attentionally demanding visual search tasks.

Coordinate systems for spatial attention

We are currently investigating the  coordinate system used to encode a sustained locus of spatial attention. Specifically, we are interested in whether the native representation of spatial attention is spatiotopic (i.e., world- or head-centered) or retinotopic (eye-centered). Current work suggests that spatial attention operates in a retintopic coordinate frame, consistent with a retintopically organized salience map.

Natural vision

We are also part of the “natural scenes” gang. Several ongoing projects in the lab are investigating neuronal responses to complex natural scene stimuli. We also do “free-viewing” experiments, in which observers are free to make voluntary eye movements during the course of an experimental session. These experiments are intended to identify interactions between the visual and oculomotor system as well as use oculomotor behavior as a tool for inferring information about the internal state of observers.

Contributions of the “non-classical surround” to visual selectivity

In collaboration with the McCormick Lab, we are investigating how the non-classical surround portion of the receptive field in area 17 (aka V1) contributes to visual selectivity. Specifically, we are interested in how surround stimulation increases the lifetime sparseness of visual responses which is thought to increase the metabolic efficiency of the visual representation used by visual cortex.