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Frontal non-invasive neurostimulation modulates antisaccade preparation in non-human primates.

Valero-Cabre A, Wattiez N, Monfort M, François C, Rivaud-Péchoux S, Gaymard B, Pouget P - PLoS ONE (2012)

Bottom Line: We show that online single pulse TMS significantly modulated antisaccade latencies.Such effects proved dependent on TMS site (effects on FEF but not on an actively stimulated control site), TMS modality (present under active but not sham TMS on the FEF area), TMS intensity (intensities of at least 40% of the TMS machine maximal output required), TMS timing (more robust for pulses delivered at 150 ms than at 100 post target onset) and visual hemifield (relative latency decreases mainly for ipsilateral AS).Our results demonstrate the feasibility of using TMS to causally modulate antisaccade-associated computations in the non-human primate brain and support the use of this approach in monkeys to study brain function and its non-invasive neuromodulation for exploratory and therapeutic purposes.

View Article: PubMed Central - PubMed

Affiliation: Université Pierre et Marie Curie, CNRS UMR 7225, INSERM UMRS 975, Institut du Cerveau et la Möelle (ICM), Paris, France. antoni.valerocabre@upmc.fr

ABSTRACT
A combination of oculometric measurements, invasive electrophysiological recordings and microstimulation have proven instrumental to study the role of the Frontal Eye Field (FEF) in saccadic activity. We hereby gauged the ability of a non-invasive neurostimulation technology, Transcranial Magnetic Stimulation (TMS), to causally interfere with frontal activity in two macaque rhesus monkeys trained to perform a saccadic antisaccade task. We show that online single pulse TMS significantly modulated antisaccade latencies. Such effects proved dependent on TMS site (effects on FEF but not on an actively stimulated control site), TMS modality (present under active but not sham TMS on the FEF area), TMS intensity (intensities of at least 40% of the TMS machine maximal output required), TMS timing (more robust for pulses delivered at 150 ms than at 100 post target onset) and visual hemifield (relative latency decreases mainly for ipsilateral AS). Our results demonstrate the feasibility of using TMS to causally modulate antisaccade-associated computations in the non-human primate brain and support the use of this approach in monkeys to study brain function and its non-invasive neuromodulation for exploratory and therapeutic purposes.

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TMS coil positioning.Schematic drawing of the smallest of the commercially available coils, which was used for this experiment (Upper panel), a custom-made ∼25 mm loop radius figure-of-eight TMS coil (exact dimensions of the coil used indicated in the figure) (Magstim Company, Carmathenshire, Wales). (Bottom panel) X-rays photography of monkey ‘C’. The red target represents the estimated stereotaxic coordinates of the monkey’s FEF area. The length of the white bar illustrates approximate differences in bone thickness between the human and the macaque skull at frontal locations.
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pone-0038674-g003: TMS coil positioning.Schematic drawing of the smallest of the commercially available coils, which was used for this experiment (Upper panel), a custom-made ∼25 mm loop radius figure-of-eight TMS coil (exact dimensions of the coil used indicated in the figure) (Magstim Company, Carmathenshire, Wales). (Bottom panel) X-rays photography of monkey ‘C’. The red target represents the estimated stereotaxic coordinates of the monkey’s FEF area. The length of the white bar illustrates approximate differences in bone thickness between the human and the macaque skull at frontal locations.

Mentions: The FEF field was identified according to stereotaxic coordinates for this location and its site labeled with a color marker on the monkey scalp, which lasted for several weeks and was renewed when fading. The figure of eight TMS coil center was positioned over this location at every session and oriented in a lateral-to-medial and caudal-to-rostral 45-degree orientation with regards to the scalp midline. The TMS coil was held steady on the same position by means of a well-tightened 180-degrees-of-freedom short mechanical arm attached to the upper lateral side of the monkey chair, ending in a C rubber clamp (Figure 2 and 3). The monkey head was posted to avoid any movements. The TMS coil pulse can generate some brief skull vibration (the monophasic pulse may last ∼120–150 microseconds) but such effects are minimized if not non-existent with single pulse paradigms as the ones we used in this study. In any case, we visually inspected at the beginning and the end of each block the position of the coil on the targeted area to make sure its position did not shift with regards to its target.


Frontal non-invasive neurostimulation modulates antisaccade preparation in non-human primates.

Valero-Cabre A, Wattiez N, Monfort M, François C, Rivaud-Péchoux S, Gaymard B, Pouget P - PLoS ONE (2012)

TMS coil positioning.Schematic drawing of the smallest of the commercially available coils, which was used for this experiment (Upper panel), a custom-made ∼25 mm loop radius figure-of-eight TMS coil (exact dimensions of the coil used indicated in the figure) (Magstim Company, Carmathenshire, Wales). (Bottom panel) X-rays photography of monkey ‘C’. The red target represents the estimated stereotaxic coordinates of the monkey’s FEF area. The length of the white bar illustrates approximate differences in bone thickness between the human and the macaque skull at frontal locations.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368878&req=5

pone-0038674-g003: TMS coil positioning.Schematic drawing of the smallest of the commercially available coils, which was used for this experiment (Upper panel), a custom-made ∼25 mm loop radius figure-of-eight TMS coil (exact dimensions of the coil used indicated in the figure) (Magstim Company, Carmathenshire, Wales). (Bottom panel) X-rays photography of monkey ‘C’. The red target represents the estimated stereotaxic coordinates of the monkey’s FEF area. The length of the white bar illustrates approximate differences in bone thickness between the human and the macaque skull at frontal locations.
Mentions: The FEF field was identified according to stereotaxic coordinates for this location and its site labeled with a color marker on the monkey scalp, which lasted for several weeks and was renewed when fading. The figure of eight TMS coil center was positioned over this location at every session and oriented in a lateral-to-medial and caudal-to-rostral 45-degree orientation with regards to the scalp midline. The TMS coil was held steady on the same position by means of a well-tightened 180-degrees-of-freedom short mechanical arm attached to the upper lateral side of the monkey chair, ending in a C rubber clamp (Figure 2 and 3). The monkey head was posted to avoid any movements. The TMS coil pulse can generate some brief skull vibration (the monophasic pulse may last ∼120–150 microseconds) but such effects are minimized if not non-existent with single pulse paradigms as the ones we used in this study. In any case, we visually inspected at the beginning and the end of each block the position of the coil on the targeted area to make sure its position did not shift with regards to its target.

Bottom Line: We show that online single pulse TMS significantly modulated antisaccade latencies.Such effects proved dependent on TMS site (effects on FEF but not on an actively stimulated control site), TMS modality (present under active but not sham TMS on the FEF area), TMS intensity (intensities of at least 40% of the TMS machine maximal output required), TMS timing (more robust for pulses delivered at 150 ms than at 100 post target onset) and visual hemifield (relative latency decreases mainly for ipsilateral AS).Our results demonstrate the feasibility of using TMS to causally modulate antisaccade-associated computations in the non-human primate brain and support the use of this approach in monkeys to study brain function and its non-invasive neuromodulation for exploratory and therapeutic purposes.

View Article: PubMed Central - PubMed

Affiliation: Université Pierre et Marie Curie, CNRS UMR 7225, INSERM UMRS 975, Institut du Cerveau et la Möelle (ICM), Paris, France. antoni.valerocabre@upmc.fr

ABSTRACT
A combination of oculometric measurements, invasive electrophysiological recordings and microstimulation have proven instrumental to study the role of the Frontal Eye Field (FEF) in saccadic activity. We hereby gauged the ability of a non-invasive neurostimulation technology, Transcranial Magnetic Stimulation (TMS), to causally interfere with frontal activity in two macaque rhesus monkeys trained to perform a saccadic antisaccade task. We show that online single pulse TMS significantly modulated antisaccade latencies. Such effects proved dependent on TMS site (effects on FEF but not on an actively stimulated control site), TMS modality (present under active but not sham TMS on the FEF area), TMS intensity (intensities of at least 40% of the TMS machine maximal output required), TMS timing (more robust for pulses delivered at 150 ms than at 100 post target onset) and visual hemifield (relative latency decreases mainly for ipsilateral AS). Our results demonstrate the feasibility of using TMS to causally modulate antisaccade-associated computations in the non-human primate brain and support the use of this approach in monkeys to study brain function and its non-invasive neuromodulation for exploratory and therapeutic purposes.

Show MeSH