Mapping Cortical Activity Elicited with Electrical Microstimulation Using fMRI in the Macaque

• Published in: Neuron (Cambridge, Mass.) Vol. 48; no. 6; pp. 901 - 911
• Main Authors: Tolias, Andreas S., Sultan, Fahad, Augath, Mark, Oeltermann, Axel, Tehovnik, Edward J., Schiller, Peter H., Logothetis, Nikos K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 22.12.2005; Elsevier Limited
• Subjects: Action Potentials - physiology; Animals; Behavior; Brain; Brain Mapping - instrumentation; Brain Mapping - methods; Electric Stimulation - instrumentation; Electric Stimulation - methods; Electrodes; Evoked Potentials, Visual - physiology; Experiments; Macaca; Macaca mulatta; Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - methods; Microelectrodes; Neural Conduction - physiology; Neurons - physiology; NMR; Nuclear magnetic resonance; Primates; Standard deviation; Synapses - physiology; Synaptic Transmission - physiology; Visual Cortex - anatomy & histology; Visual Cortex - physiology; Visual Pathways - anatomy & histology; Visual Pathways - physiology; Visual Perception - physiology
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2005.11.034

Over the last two centuries, electrical microstimulation has been used to demonstrate causal links between neural activity and specific behaviors and cognitive functions. However, to establish these links it is imperative to characterize the cortical activity patterns that are elicited by stimulation locally around the electrode and in other functionally connected areas. We have developed a technique to record brain activity using the blood oxygen level dependent (BOLD) signal while applying electrical microstimulation to the primate brain. We find that the spread of activity around the electrode tip in macaque area V1 was larger than expected from calculations based on passive spread of current and therefore may reflect functional spread by way of horizontal connections. Consistent with this functional transynaptic spread we also obtained activation in expected projection sites in extrastriate visual areas, demonstrating the utility of our technique in uncovering in vivo functional connectivity maps.