Pharmaco-based fMRI and neurophysiology in non-human primates

Brain activity is continuously changing, among others reflecting the effects of neuromodulation on multiple spatial and temporal scales. By altering the input–output relationship of neural circuits, neuromodulators can also affect their energy expenditure, with concomitant effects on the hemodynamic responses. Yet, it is still unclear how to study and interpret the effects of different neuromodulators, for instance, how to differentiate their effects from underlying behavior- or stimulus-driven activity. Gaining insights into neuromodulatory processes is largely hampered by the lack of approaches providing information concurrently at different spatio-temporal scales. Here, we provide an overview of the multimodal approach consisting of functional magnetic resonance imaging (fMRI), pharmacology and neurophysiology, which we developed to elucidate causal relationships between neuromodulation and neurovascular coupling in visual cortex of anesthetized macaques.