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Abstract:
In the primate brain a frontoparietal network is involved in many aspects of cognitive control, e.g. during shifts of attention and switches of abstract rules. However, the frontoparietal network in the human brain is also active during simple update of attended information, when task-related decision making is minimal (1) or during the execution of voluntary eye movements (2). The goal of the present study was to identify the network of areas activated by a short series of visual stimuli (meaningless fractal images) while the animals were awake and maintained fixation, in order to compare with the activations elicited in the human brain and to inform and direct future single unit recordings. We obtained activation maps at 7T using BOLD fMRI in three alert macaque monkeys (Macaca mulatta). Functional images were realigned and co-registered with the high-resolution MRI images used in the Saleem and Logothetis atlas (3) to facilitate the identification of the anatomical structures. Areas that were reliably activated in all three animals included areas 8 and F5 around the arcuate sulcus (AS), and the lateral intraparietal area (LIP), along with early and higher areas of the visual system. As in the human, extensive frontoparietal activity was seen despite maintained fixation, and without active behavioural decisions.
Additionally, we present preliminary psychophysical and BOLD fMRI results from a second study. In this experiment, we trained one animal to perform a colour discrimination task by making a saccade to the left (for green) or right (for red) of the screen, and then introduced conditions of increased task difficulty.
