BOLD fMRI activation for anti-saccades in nonhuman primates.

Most of our knowledge about the functional organization of the nonhuman primate brain has come from single neuron recordings, whereas functional magnetic resonance imaging (fMRI) has rapidly become the method of choice for the study of the human brain. In some cases these two methods have resulted in conflicting models of frontal lobe function. Based on the finding that the frontal eye fields (FEF) exhibit a higher blood-oxygenation-level dependent (BOLD) activation for anti-saccades compared with pro-saccades, it has been proposed that this area is more involved in voluntary than automatic saccade generation. This model has been questioned by the finding of decreased single neuron activity in FEF for anti-compared with pro-saccades in monkeys. To reconcile these findings, we employed fMRI to compare BOLD activation between anti-saccades and pro-saccades in monkeys. FEF and a number of other cortical and subcortical areas showed an increased activation for anti-saccades. The results indicate that previous contrary findings between single neuron recordings and fMRI were due to differences between these techniques and were not related to differences between the two primate species.