Dai J, Brooks DI, Sheinberg DL (2014). Optogenetic and electrical stimulation systematically bias visuospatial choice in primates. Current Biology, 24, 63-69.

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Abstract

Optogenetics is a recently developed method in which neurons are genetically modified to express membrane proteins sensitive to light, enabling precisely targeted control of neural activity [1, 2, 3]. The temporal and spatial precision afforded by neural stimulation by light holds promise as a powerful alternative to current methods of neural control, which rely predominantly on electrical and pharmacological methods, in both research and clinical settings [4, 5]. Although the optogenetic approach has been widely used in rodent and other small animal models to study neural circuitry [6, 7, 8], its functional application in primate models has proven more difficult. In contrast to the relatively large literature on the effects of cortical electrical microstimulation in perceptual and decision-making tasks [9, 10, 11, 12, 13], previous studies of optogenetic stimulation in primates have not demonstrated its utility in similar paradigms [14, 15, 16, 17, 18]. In this study, we directly compare the effects of optogenetic activation and electrical microstimulation in the lateral intraparietal area during a visuospatial discrimination task. We observed significant and predictable biases in visual attention in response to both forms of stimulation that are consistent with the experimental modulation of a visual salience map. Our results demonstrate the power of optogenetics as a viable alternative to electrical microstimulation for the precise dissection of the cortical pathways of high-level processes in the primate brain.

Dotson NM, Salazar RF, Gray CM (2014). Fronto-parietal correlation dynamics reveal interplay between integration and segregation during visual working memory. J Neuroscience, 34(41):13600-13.

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Abstract

Working memory requires large-scale cooperation among widespread cortical and subcortical brain regions. Importantly, these processes must achieve an appropriate balance between functional integration and segregation, which are thought to be mediated by task-dependent spatiotemporal patterns of correlated activity. Here, we used cross-correlation analysis to estimate the incidence, magnitude, and relative phase angle of temporally correlated activity from simultaneous local field potential recordings in a network of prefrontal and posterior parietal cortical areas in monkeys performing an oculomotor, delayed match-to-sample task. We found long-range intraparietal and frontoparietal correlations that display a bimodal distribution of relative phase values, centered near 0° and 180°, suggesting a possible basis for functional segregation among distributed networks. Both short- and long-range correlations display striking task-dependent transitions in strength and relative phase, indicating that cognitive events are accompanied by robust changes in the pattern of temporal coordination across the frontoparietal network.