About the specificity of epidural field potentials recorded with high-density multi-electrode arrays from the primary visual cortex

This thesis contains five studies, two of which were previously published. The first four studies used epidural field potentials (EFPs) recorded with high-density multi-electrode arrays from the primary visual cortex of macaque monkeys performing different tasks. The main focus of these studies was to investigate whether task-evoked changes in the cortical activity modulate EFPs and to what extent sensory and cognitive information can be decoded from EFPs. In the first study (published previously), single-trial EFPs enabled a precise differentiation between multiple visually stimulated locations demonstrating a high spatial specificity of EFPs. In the second and third study, EFPs were modulated by stimulus size, shape and contrast revealing that EFPs are sensitive to small changes in the visual stimulation. In the fourth study, EFPs were modulated by the allocation of covert spatial attention indicating that EFPs are sensitive to changes in the cortical activity evoked by cognitive tasks. In addition, task-relevant evoked potentials of EFPs were correlated with the response time of the monkey. Finally, the fifth study (published previously) documents and demonstrates an effective method of training macaque monkeys on cognitive tasks.