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Vortrag

Microstimulation and fMRI in anesthetized and alert monkeys: Conditions for transsynaptic BOLD activation

MPG-Autoren
http://pubman.mpdl.mpg.de/cone/persons/resource/persons84063

Logothetis,  NK
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84099

Sultan F, Murayama,  Y
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons83787

Augath,  M
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84237

Steudel,  T
Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society;
Dept. Empirical Inference, Max Planck Institute for Intelligent System, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons84733

Oeltermann,  A
Max Planck Institute for Biological Cybernetics, Max Planck Society;

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Zitation

Logothetis, N., Sultan F, Murayama, Y., Augath, M., Steudel, T., & Oeltermann, A. (2006). Microstimulation and fMRI in anesthetized and alert monkeys: Conditions for transsynaptic BOLD activation. Talk presented at 36th Annual Meeting of the Society for Neuroscience (Neuroscience 2006). Atlanta, GA, USA.


Zitierlink: http://hdl.handle.net/11858/00-001M-0000-0013-D013-B
Zusammenfassung
We have recently combined electrical stimulation and fMRI and demonstrated that the excitability properties of the directly stimulated elements in neocortex using this method are very similar to those obtained with either intracortical recordings or behavioral methods (Tolias et al., 2005). Microstimulation in cortical area V1 of the macaque activated mainly the pyramidal fibers, and the effective current spread, that was measured by means of the BOLD activation, was found to be greater than that obtained with the other two methods. Stimulation of V1 (and in later studies of MT), however, revealed mainly the monosynaptic targets of each stimulated region. Here we set out to elucidate the conditions for which transsynaptic effects can be obtained. Experiments were conducted in anesthetized and alert monkeys in a 4.7T/40cm and 7T/60 scanner, respectively. Electrical stimulation was delivered using a biphasic pulse generator attached to a constant-current stimulus isolation unit. Constant-current charge-balanced, band-limited pulses of different center frequency, pulse duration and current strength were delivered to the brain for periods of 4 sec preceded and followed by 4 sec and 12 sec blank periods, respectively. The compensation circuit, designed to minimize interference generated by the switching gradients during recording, was always active, alleviating all gradient-induced currents in the range of the stimulation current. Local microstimulation was applied in dLGN, pulvinar, striate and extrastriate cortex. The areas activated upon stimulation of each of these sites was found to depend primarily on the central frequency of the frequency band used. Transsynaptic activation also depended on stimulation condition. Differences between the anesthetized and alert monkey experiments will be discussed.