Limits...
Brain oscillatory activity during motor preparation: effect of directional uncertainty on beta, but not alpha, frequency band.

Tzagarakis C, West S, Pellizzer G - Front Neurosci (2015)

Bottom Line: During cue presentation, the reduction of power of the alpha-band in the occipital lobe showed a brief differentiation of condition: the wider the visual cue, the more the power of the alpha-band decreased.However, during motor preparation, only the power of the beta-band was dependent on directional uncertainty: the less the directional uncertainty, the more the power of the beta-band decreased.In conclusion, the results indicate that the power in the alpha-band is associated briefly with cue size, but is otherwise an undifferentiated indication of neural activation, whereas the power of the beta-band reflects the level of motor preparation.

View Article: PubMed Central - PubMed

Affiliation: Brain Sciences Center, Veterans Affairs Health Care Service Minneapolis, MN, USA ; Department of Neuroscience, University of Minnesota Minneapolis, MN, USA.

ABSTRACT
In time-constraint activities, such as sports, it is advantageous to be prepared to act even before knowing precisely what action will be needed. Here, we studied the relation between neural oscillations during motor preparation and amount of uncertainty about the direction of the upcoming target. Ten right-handed volunteers participated in a cued center-out task. A brief visual cue identified the region of space in which the target would appear. Three cue sizes were used to vary the amount of information about the direction of the upcoming target. The target appeared at a random location within the region indicated by the cue, and the participants moved a joystick-controlled cursor toward it. Time-frequency analyses showed phasic increases of power in low (delta/theta: <7 Hz) and high (gamma: >30 Hz) frequency-bands in relation to the onset of visual stimuli and of the motor response. More importantly in regard to motor preparation, there was a tonic reduction of power in the alpha (8-12 Hz) and beta (14-30 Hz) bands during the period between cue presentation and target onset. During motor preparation, the main source of change of power of the alpha band was localized over the contralateral sensorimotor region and both parietal cortices, whereas for the beta-band the main source was the contralateral sensorimotor region. During cue presentation, the reduction of power of the alpha-band in the occipital lobe showed a brief differentiation of condition: the wider the visual cue, the more the power of the alpha-band decreased. However, during motor preparation, only the power of the beta-band was dependent on directional uncertainty: the less the directional uncertainty, the more the power of the beta-band decreased. In conclusion, the results indicate that the power in the alpha-band is associated briefly with cue size, but is otherwise an undifferentiated indication of neural activation, whereas the power of the beta-band reflects the level of motor preparation.

No MeSH data available.


Task and reaction time. (A) Cues of different directional range (0°, 90°, or 180°) indicated the area in which the upcoming target could appear. These cues were presented in any random direction around the center. (B) Schematic sequence of events of the instructed-delay task. To start a trial, the subjects fixated and held the joystick-controlled cursor in the center of the display for 3 s. Then, a cue -instructing the subjects about the possible location of the upcoming target- was presented for 0.5 s. The figure shows a trial with the 90° cue range. After a randomly variable 1–1.5 s delay period, the target was presented at a random location within the range indicated by the cue. The subjects had to move the cursor quickly and accurately from the center toward the target. In addition, the subjects were instructed to fixate the center of the screen from the center-hold period to the onset of the target. An inter-trial interval (ITI) of 3 s followed each trial. (C) The reaction time (RT) was defined as the duration between the onset of the target and the onset of the response, which was determined by the exit of the cursor from the center window. The harmonic mean of RT is plotted against cue range. The error bars indicate the standard error of the mean across subjects (N = 10). RT increased significantly with the directional range of the cue.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4508519&req=5

Figure 1: Task and reaction time. (A) Cues of different directional range (0°, 90°, or 180°) indicated the area in which the upcoming target could appear. These cues were presented in any random direction around the center. (B) Schematic sequence of events of the instructed-delay task. To start a trial, the subjects fixated and held the joystick-controlled cursor in the center of the display for 3 s. Then, a cue -instructing the subjects about the possible location of the upcoming target- was presented for 0.5 s. The figure shows a trial with the 90° cue range. After a randomly variable 1–1.5 s delay period, the target was presented at a random location within the range indicated by the cue. The subjects had to move the cursor quickly and accurately from the center toward the target. In addition, the subjects were instructed to fixate the center of the screen from the center-hold period to the onset of the target. An inter-trial interval (ITI) of 3 s followed each trial. (C) The reaction time (RT) was defined as the duration between the onset of the target and the onset of the response, which was determined by the exit of the cursor from the center window. The harmonic mean of RT is plotted against cue range. The error bars indicate the standard error of the mean across subjects (N = 10). RT increased significantly with the directional range of the cue.

Mentions: The task was an instructed-delay reaching task in which a brief (0.5 s) visually presented cue indicated the range of directions in which the upcoming target could appear. Three cue sizes were used corresponding to target directional uncertainty ranges of 0°, 90°, and 180° (see Figure 1A). These cues were presented in any direction around the center of the screen. Trials with different cue range and direction were randomly shuffled. The target appeared at an equiprobable random direction within the range identified by the 90° or 180° cue. By definition with the 0° cue, the target could appear only at a single location within the cue. Each cue size was presented at least 60 times. When an error occurred (see below), the trial was reinserted randomly in the sequence of remaining trials, so that each subject had a complete set of 180 (i.e., 3 cue sizes × 60 repetitions) correct trials in the task. A block of 12 practice trials preceded the actual recording.


Brain oscillatory activity during motor preparation: effect of directional uncertainty on beta, but not alpha, frequency band.

Tzagarakis C, West S, Pellizzer G - Front Neurosci (2015)

Task and reaction time. (A) Cues of different directional range (0°, 90°, or 180°) indicated the area in which the upcoming target could appear. These cues were presented in any random direction around the center. (B) Schematic sequence of events of the instructed-delay task. To start a trial, the subjects fixated and held the joystick-controlled cursor in the center of the display for 3 s. Then, a cue -instructing the subjects about the possible location of the upcoming target- was presented for 0.5 s. The figure shows a trial with the 90° cue range. After a randomly variable 1–1.5 s delay period, the target was presented at a random location within the range indicated by the cue. The subjects had to move the cursor quickly and accurately from the center toward the target. In addition, the subjects were instructed to fixate the center of the screen from the center-hold period to the onset of the target. An inter-trial interval (ITI) of 3 s followed each trial. (C) The reaction time (RT) was defined as the duration between the onset of the target and the onset of the response, which was determined by the exit of the cursor from the center window. The harmonic mean of RT is plotted against cue range. The error bars indicate the standard error of the mean across subjects (N = 10). RT increased significantly with the directional range of the cue.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508519&req=5

Figure 1: Task and reaction time. (A) Cues of different directional range (0°, 90°, or 180°) indicated the area in which the upcoming target could appear. These cues were presented in any random direction around the center. (B) Schematic sequence of events of the instructed-delay task. To start a trial, the subjects fixated and held the joystick-controlled cursor in the center of the display for 3 s. Then, a cue -instructing the subjects about the possible location of the upcoming target- was presented for 0.5 s. The figure shows a trial with the 90° cue range. After a randomly variable 1–1.5 s delay period, the target was presented at a random location within the range indicated by the cue. The subjects had to move the cursor quickly and accurately from the center toward the target. In addition, the subjects were instructed to fixate the center of the screen from the center-hold period to the onset of the target. An inter-trial interval (ITI) of 3 s followed each trial. (C) The reaction time (RT) was defined as the duration between the onset of the target and the onset of the response, which was determined by the exit of the cursor from the center window. The harmonic mean of RT is plotted against cue range. The error bars indicate the standard error of the mean across subjects (N = 10). RT increased significantly with the directional range of the cue.
Mentions: The task was an instructed-delay reaching task in which a brief (0.5 s) visually presented cue indicated the range of directions in which the upcoming target could appear. Three cue sizes were used corresponding to target directional uncertainty ranges of 0°, 90°, and 180° (see Figure 1A). These cues were presented in any direction around the center of the screen. Trials with different cue range and direction were randomly shuffled. The target appeared at an equiprobable random direction within the range identified by the 90° or 180° cue. By definition with the 0° cue, the target could appear only at a single location within the cue. Each cue size was presented at least 60 times. When an error occurred (see below), the trial was reinserted randomly in the sequence of remaining trials, so that each subject had a complete set of 180 (i.e., 3 cue sizes × 60 repetitions) correct trials in the task. A block of 12 practice trials preceded the actual recording.

Bottom Line: During cue presentation, the reduction of power of the alpha-band in the occipital lobe showed a brief differentiation of condition: the wider the visual cue, the more the power of the alpha-band decreased.However, during motor preparation, only the power of the beta-band was dependent on directional uncertainty: the less the directional uncertainty, the more the power of the beta-band decreased.In conclusion, the results indicate that the power in the alpha-band is associated briefly with cue size, but is otherwise an undifferentiated indication of neural activation, whereas the power of the beta-band reflects the level of motor preparation.

View Article: PubMed Central - PubMed

Affiliation: Brain Sciences Center, Veterans Affairs Health Care Service Minneapolis, MN, USA ; Department of Neuroscience, University of Minnesota Minneapolis, MN, USA.

ABSTRACT
In time-constraint activities, such as sports, it is advantageous to be prepared to act even before knowing precisely what action will be needed. Here, we studied the relation between neural oscillations during motor preparation and amount of uncertainty about the direction of the upcoming target. Ten right-handed volunteers participated in a cued center-out task. A brief visual cue identified the region of space in which the target would appear. Three cue sizes were used to vary the amount of information about the direction of the upcoming target. The target appeared at a random location within the region indicated by the cue, and the participants moved a joystick-controlled cursor toward it. Time-frequency analyses showed phasic increases of power in low (delta/theta: <7 Hz) and high (gamma: >30 Hz) frequency-bands in relation to the onset of visual stimuli and of the motor response. More importantly in regard to motor preparation, there was a tonic reduction of power in the alpha (8-12 Hz) and beta (14-30 Hz) bands during the period between cue presentation and target onset. During motor preparation, the main source of change of power of the alpha band was localized over the contralateral sensorimotor region and both parietal cortices, whereas for the beta-band the main source was the contralateral sensorimotor region. During cue presentation, the reduction of power of the alpha-band in the occipital lobe showed a brief differentiation of condition: the wider the visual cue, the more the power of the alpha-band decreased. However, during motor preparation, only the power of the beta-band was dependent on directional uncertainty: the less the directional uncertainty, the more the power of the beta-band decreased. In conclusion, the results indicate that the power in the alpha-band is associated briefly with cue size, but is otherwise an undifferentiated indication of neural activation, whereas the power of the beta-band reflects the level of motor preparation.

No MeSH data available.