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Distinct control of initiation and metrics of memory-guided saccades and vergence by the FEF: a TMS study.

Yang Q, Kapoula Z - PLoS ONE (2011)

Bottom Line: This study is to explore the effect of transcranial magnetic simulation (TMS) over FEF on the control of memory-guided saccade-vergence eye movements.TMS of the FEF also altered the accuracy but only for leftward saccades combined with either convergence or divergence; intrasaccadic vergence also increased after TMS of the FEF.The results suggest anisotropy in the quality of space memory and are discussed in the context of other known perceptual motor anisotropies.

View Article: PubMed Central - PubMed

Affiliation: IRIS Group, UMR 8194, CNRS, Hôpital Européen Georges Pompidou, Paris, France. qing.yang@egp.aphp.fr

ABSTRACT

Background: The initiation of memory guided saccades is known to be controlled by the frontal eye field (FEF). Recent physiological studies showed the existence of an area close to FEF that controls also vergence initiation and execution. This study is to explore the effect of transcranial magnetic simulation (TMS) over FEF on the control of memory-guided saccade-vergence eye movements.

Methodology/principal findings: Subjects had to make an eye movement in dark towards a target flashed 1 sec earlier (memory delay); the location of the target relative to fixation point was such as to require either a vergence along the median plane, or a saccade, or a saccade with vergence; trials were interleaved. Single pulse TMS was applied on the left or right FEF; it was delivered at 100 ms after the end of memory delay, i.e. extinction of fixation LED that was the "go" signal. Twelve healthy subjects participated in the study. TMS of left or right FEF prolonged the latency of all types of eye movements; the increase varied from 21 to 56 ms and was particularly strong for the divergence movements. This indicates that FEF is involved in the initiation of all types of memory guided movement in the 3D space. TMS of the FEF also altered the accuracy but only for leftward saccades combined with either convergence or divergence; intrasaccadic vergence also increased after TMS of the FEF.

Conclusions/significance: The results suggest anisotropy in the quality of space memory and are discussed in the context of other known perceptual motor anisotropies.

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Mean values of percentage of TMS effects in latency, (TMS-noTMS)/noTMS.(A) TMS of right FEF and (B) TMS of left FEF for divergence, saccades, convergence, and saccade components, convergence components and divergence components of combined movements under the conditions of TMS over the right or the left FEF. Such value is higher for divergence than for any other types of eye movements.
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pone-0020322-g002: Mean values of percentage of TMS effects in latency, (TMS-noTMS)/noTMS.(A) TMS of right FEF and (B) TMS of left FEF for divergence, saccades, convergence, and saccade components, convergence components and divergence components of combined movements under the conditions of TMS over the right or the left FEF. Such value is higher for divergence than for any other types of eye movements.

Mentions: Figure 1 presents the group mean latency for saccades to left or to right, for divergence and convergence (A), for components of combined convergent movements (B) and for components of combined divergent movements (C); data are shown under no-TMS, TMS over the right or left FEF conditions. Two-way ANOVA showed significant main effect of the TMS (F(11,121) = 6.66, p<0.001), i.e., longer latency after TMS over the right or the left FEF relative to no-TMS; and also significant effect of the type of eye movement (F(2,22) = 21.69, p<0.001). Post-hoc analysis showed that the effect of TMS was significant for each type of eye movement: saccade, vergence or combined eye movements (all p<0.05). Divergence showed significantly shorter latency than any other type of eye movements (all p<0.05). We calculated the percentage of latency changes after TMS, i.e. (TMS - noTMS)/noTMS, and found that such percentage was higher for divergence (28% for TMS of right FEF, 23% for TMS of left FEF) than other type of eye movements (from 12% to 16%, see Figure 2). This suggests that TMS effect is stronger for the movements which have naturally the shortest latency, such as divergence.


Distinct control of initiation and metrics of memory-guided saccades and vergence by the FEF: a TMS study.

Yang Q, Kapoula Z - PLoS ONE (2011)

Mean values of percentage of TMS effects in latency, (TMS-noTMS)/noTMS.(A) TMS of right FEF and (B) TMS of left FEF for divergence, saccades, convergence, and saccade components, convergence components and divergence components of combined movements under the conditions of TMS over the right or the left FEF. Such value is higher for divergence than for any other types of eye movements.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3102701&req=5

pone-0020322-g002: Mean values of percentage of TMS effects in latency, (TMS-noTMS)/noTMS.(A) TMS of right FEF and (B) TMS of left FEF for divergence, saccades, convergence, and saccade components, convergence components and divergence components of combined movements under the conditions of TMS over the right or the left FEF. Such value is higher for divergence than for any other types of eye movements.
Mentions: Figure 1 presents the group mean latency for saccades to left or to right, for divergence and convergence (A), for components of combined convergent movements (B) and for components of combined divergent movements (C); data are shown under no-TMS, TMS over the right or left FEF conditions. Two-way ANOVA showed significant main effect of the TMS (F(11,121) = 6.66, p<0.001), i.e., longer latency after TMS over the right or the left FEF relative to no-TMS; and also significant effect of the type of eye movement (F(2,22) = 21.69, p<0.001). Post-hoc analysis showed that the effect of TMS was significant for each type of eye movement: saccade, vergence or combined eye movements (all p<0.05). Divergence showed significantly shorter latency than any other type of eye movements (all p<0.05). We calculated the percentage of latency changes after TMS, i.e. (TMS - noTMS)/noTMS, and found that such percentage was higher for divergence (28% for TMS of right FEF, 23% for TMS of left FEF) than other type of eye movements (from 12% to 16%, see Figure 2). This suggests that TMS effect is stronger for the movements which have naturally the shortest latency, such as divergence.

Bottom Line: This study is to explore the effect of transcranial magnetic simulation (TMS) over FEF on the control of memory-guided saccade-vergence eye movements.TMS of the FEF also altered the accuracy but only for leftward saccades combined with either convergence or divergence; intrasaccadic vergence also increased after TMS of the FEF.The results suggest anisotropy in the quality of space memory and are discussed in the context of other known perceptual motor anisotropies.

View Article: PubMed Central - PubMed

Affiliation: IRIS Group, UMR 8194, CNRS, Hôpital Européen Georges Pompidou, Paris, France. qing.yang@egp.aphp.fr

ABSTRACT

Background: The initiation of memory guided saccades is known to be controlled by the frontal eye field (FEF). Recent physiological studies showed the existence of an area close to FEF that controls also vergence initiation and execution. This study is to explore the effect of transcranial magnetic simulation (TMS) over FEF on the control of memory-guided saccade-vergence eye movements.

Methodology/principal findings: Subjects had to make an eye movement in dark towards a target flashed 1 sec earlier (memory delay); the location of the target relative to fixation point was such as to require either a vergence along the median plane, or a saccade, or a saccade with vergence; trials were interleaved. Single pulse TMS was applied on the left or right FEF; it was delivered at 100 ms after the end of memory delay, i.e. extinction of fixation LED that was the "go" signal. Twelve healthy subjects participated in the study. TMS of left or right FEF prolonged the latency of all types of eye movements; the increase varied from 21 to 56 ms and was particularly strong for the divergence movements. This indicates that FEF is involved in the initiation of all types of memory guided movement in the 3D space. TMS of the FEF also altered the accuracy but only for leftward saccades combined with either convergence or divergence; intrasaccadic vergence also increased after TMS of the FEF.

Conclusions/significance: The results suggest anisotropy in the quality of space memory and are discussed in the context of other known perceptual motor anisotropies.

Show MeSH