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J. Patrick Mayo, Amie DiTomasso, Marc Sommer, Matt A. Smith; An improved method for mapping neuronal receptive fields in prefrontal cortex. Journal of Vision 2012;12(9):81. doi: 10.1167/12.9.81.
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© ARVO (1962-2015); The Authors (2016-present)
The frontal eye field (FEF) is a region of prefrontal cortex that plays an important role in vision and eye movements. Single neurons in FEF are responsive to stimuli in specific regions of visual space known as the receptive field (RF). Despite their importance, FEF RF properties have seldom been systematically measured. Additionally, RF properties can change over time. For example, around the time of eye movements RFs can move predictively based on the impending saccade direction. These peri-saccadic RFs have been shown to "jump" in FEF and "expand" in visuomotor area LIP. In the absence of eye movements, similar shifting phenomena have been observed because of changes in the focus of attention. Given the ubiquity of eye movements and shifts of attention in our daily lives, changes in RFs may be frequent and dramatic. However, conventional RF mapping protocols are limited in their ability to capture the dynamic nature of RFs. RFs are generally measured outside the context of the central experimental manipulation in greatly simplified paradigms. Such RF measures tacitly assume that RFs remain stable across conditions and attentional states.
We developed a more direct measure of FEF RF dynamics. We used a slower frame rate version of "spike-triggered averaging" (STA), a technique established to measure RFs in primary visual cortex. Stimuli consisted of white dots on a black background, presented sequentially and pseudorandomly at variable locations while the monkey maintained fixation. STA estimates of RF centers and sizes matched those determined by a more conventional approach using a series of stimuli regularly spaced over fixed directions and amplitudes. We used a range of framerates to measure the temporal sensitivity of FEF neurons. Our findings validate the STA method of RF mapping in prefrontal cortex and provide greater insight into the role of FEF in visual perception.
Meeting abstract presented at VSS 2012
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