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Cortical modulations increase in early sessions with brain-machine interface.

Zacksenhouse M, Lebedev MA, Carmena JM, O'Doherty JE, Henriquez C, Nicolelis MA - PLoS ONE (2007)

Bottom Line: We conclude that the enhanced modulations are related to computational tasks that are significant especially in novel motor contexts.Although the function and neuronal mechanism of the enhanced cortical modulations are open for further inquiries, we discuss their potential role in processing execution errors and representing corrective or explorative activity.These representations are expected to contribute to the formation of internal models of the external actuator and their decoding may facilitate BMI improvement.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Mechanical Engineering, Technion, Haifa, Israel. mermz@tx.technion.ac.il

ABSTRACT

Background: During planning and execution of reaching movements, the activity of cortical motor neurons is modulated by a diversity of motor, sensory, and cognitive signals. Brain-machine interfaces (BMIs) extract part of these modulations to directly control artificial actuators. However, cortical modulations that emerge in the novel context of operating the BMI are poorly understood.

Methodology/principal findings: Here we analyzed the changes in neuronal modulations that occurred in different cortical motor areas as monkeys learned to use a BMI to control reaching movements. Using spike-train analysis methods we demonstrate that the modulations of the firing-rates of cortical neurons increased abruptly after the monkeys started operating the BMI. Regression analysis revealed that these enhanced modulations were not correlated with the kinematics of the movement. The initial enhancement in firing rate modulations declined gradually with subsequent training in parallel with the improvement in behavioral performance.

Conclusions/significance: We conclude that the enhanced modulations are related to computational tasks that are significant especially in novel motor contexts. Although the function and neuronal mechanism of the enhanced cortical modulations are open for further inquiries, we discuss their potential role in processing execution errors and representing corrective or explorative activity. These representations are expected to contribute to the formation of internal models of the external actuator and their decoding may facilitate BMI improvement.

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Related in: MedlinePlus

Effect of training: percent overall modulation POM, percent velocity modulation PVM and percent untagged modulation PUM of the Nsig significantly modulated neurons during all the 10 BMI sessions with monkey #1.Nsig = 156, 130, 142, 142, 150, 140, 160, 166, 174 and 165. Initial sessions included BCWH while later sessions included only BCWOH.
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pone-0000619-g011: Effect of training: percent overall modulation POM, percent velocity modulation PVM and percent untagged modulation PUM of the Nsig significantly modulated neurons during all the 10 BMI sessions with monkey #1.Nsig = 156, 130, 142, 142, 150, 140, 160, 166, 174 and 165. Initial sessions included BCWH while later sessions included only BCWOH.

Mentions: In all the experimental sessions, with both monkeys, the POM was always higher in brain control than in pole control, as demonstrated in Figure 11 (top panel). Furthermore, in all the control modes, the POM decreased gradually with training. These trends were statistically significant in pole control and BCWH (p<0.05). In contrast, the mean-PVM remained approximately the same, and even increased, with training (Figure 11, middle panel). The difference between the two, i.e., POM minus PVM, is depicted in the bottom panel of Figure 11, and exhibited statistically significant decreasing trends in all the control modes (p<0.02). Similar results were obtained when considering the mean-PKM, which accounts for modulations by the kinematics of the movement. Thus, the changes in POM during BMI training seem to reflect mainly changes in untagged modulations not correlated with the kinematics of the movement.


Cortical modulations increase in early sessions with brain-machine interface.

Zacksenhouse M, Lebedev MA, Carmena JM, O'Doherty JE, Henriquez C, Nicolelis MA - PLoS ONE (2007)

Effect of training: percent overall modulation POM, percent velocity modulation PVM and percent untagged modulation PUM of the Nsig significantly modulated neurons during all the 10 BMI sessions with monkey #1.Nsig = 156, 130, 142, 142, 150, 140, 160, 166, 174 and 165. Initial sessions included BCWH while later sessions included only BCWOH.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1919433&req=5

pone-0000619-g011: Effect of training: percent overall modulation POM, percent velocity modulation PVM and percent untagged modulation PUM of the Nsig significantly modulated neurons during all the 10 BMI sessions with monkey #1.Nsig = 156, 130, 142, 142, 150, 140, 160, 166, 174 and 165. Initial sessions included BCWH while later sessions included only BCWOH.
Mentions: In all the experimental sessions, with both monkeys, the POM was always higher in brain control than in pole control, as demonstrated in Figure 11 (top panel). Furthermore, in all the control modes, the POM decreased gradually with training. These trends were statistically significant in pole control and BCWH (p<0.05). In contrast, the mean-PVM remained approximately the same, and even increased, with training (Figure 11, middle panel). The difference between the two, i.e., POM minus PVM, is depicted in the bottom panel of Figure 11, and exhibited statistically significant decreasing trends in all the control modes (p<0.02). Similar results were obtained when considering the mean-PKM, which accounts for modulations by the kinematics of the movement. Thus, the changes in POM during BMI training seem to reflect mainly changes in untagged modulations not correlated with the kinematics of the movement.

Bottom Line: We conclude that the enhanced modulations are related to computational tasks that are significant especially in novel motor contexts.Although the function and neuronal mechanism of the enhanced cortical modulations are open for further inquiries, we discuss their potential role in processing execution errors and representing corrective or explorative activity.These representations are expected to contribute to the formation of internal models of the external actuator and their decoding may facilitate BMI improvement.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Mechanical Engineering, Technion, Haifa, Israel. mermz@tx.technion.ac.il

ABSTRACT

Background: During planning and execution of reaching movements, the activity of cortical motor neurons is modulated by a diversity of motor, sensory, and cognitive signals. Brain-machine interfaces (BMIs) extract part of these modulations to directly control artificial actuators. However, cortical modulations that emerge in the novel context of operating the BMI are poorly understood.

Methodology/principal findings: Here we analyzed the changes in neuronal modulations that occurred in different cortical motor areas as monkeys learned to use a BMI to control reaching movements. Using spike-train analysis methods we demonstrate that the modulations of the firing-rates of cortical neurons increased abruptly after the monkeys started operating the BMI. Regression analysis revealed that these enhanced modulations were not correlated with the kinematics of the movement. The initial enhancement in firing rate modulations declined gradually with subsequent training in parallel with the improvement in behavioral performance.

Conclusions/significance: We conclude that the enhanced modulations are related to computational tasks that are significant especially in novel motor contexts. Although the function and neuronal mechanism of the enhanced cortical modulations are open for further inquiries, we discuss their potential role in processing execution errors and representing corrective or explorative activity. These representations are expected to contribute to the formation of internal models of the external actuator and their decoding may facilitate BMI improvement.

Show MeSH
Related in: MedlinePlus