Yoshifumi Tanaka

The Influence of Audience and Monetary Reward on the Putting Kinematics of Expert and Novice Golfers.

We investigated changes in movement kinematics and attentional focus when expert and novice golfers performed a golf-putting task under pressure. Six male professional golfers and five male novice golfers performed 100 acquisition trials, followed by 10 trials in the pressure condition with a performance-contingent cash reward and small audience. After the 10 trials in the pressure condition, participants answered a questionnaire concerning attentional focus during both types of trial, including such aspects as conscious control of movements and the effects of distraction. A pressure manipulation check revealed a modest increase in physiological arousal, in that heart rate increased by about 10 bpm although state anxiety did not increase. A two-dimensional analysis of movement kinematics revealed that the amplitudes of arm and club movements decreased on the backswing in the pressure condition. Arm and club movement speed decreased on the foreswing in both experts and novices. Furthermore, neither experts nor novices changed their attentional focus in the pressure condition. Whereas previous studies of “choking under pressure™ focused on attentional changes, the kinematic changes found in the present study were possibly caused by the influences of strategy modification and/or emotional response. Choking phenomena can be explained by attentional changes, along with the influences of strategy modification and/or emotional response under pressure.

Multiple EMG Activity and Intracortical Inhibition and Facilitation During a Fine Finger Movement Under Pressure

ABSTRACT The 1st purpose of this study was to examine multiple electromyography (EMG) during voluntary hand movements. A secondary purpose was to investigate possible effects of pressure on intracortical inhibition (ICI) and intracortical facilitation (ICF) functions of the motor cortex, using paired-pulse transcranial magnetic stimulation. Twelve participants traced a 15-cm diameter target circle using a small laser pointer attached to the right index finger. After 5 acquisition trials, they performed 3 nonpressure trials followed by 3 pressure trials. The results showed that pressure had effects not only on agonist EMG activity but also on multiple muscles, such as synergist. In addition, a decrease in ICI and an increase in ICF were both observed under pressure for muscles other than the agonist.

Psychological pressure facilitates corticospinal excitability: Motor preparation processes and EMG activity in a choice reaction task

The effects of psychological pressure on corticospinal excitability and muscular activity were investigated in a two-choice reaction task that involved voluntary right index finger movements. In order to induce pressure, participants were given instructions that combined a performance-contingent cash reward, a penalty, and performance comparisons. Following practice, 11 participants performed 40 non-pressure and 40 pressure trials. Results showed successful stress induction, as indexed by significant increases in state anxiety, pulse rate, and galvanic skin response under pressure. Significant increases in the amplitude of the motor evoked potential of the right abductor pollicis brevis (APB) occurred under pressure. The maximum EMG amplitudes of APB and the first dorsal interosseous (FDI) muscle also increased significantly under pressure. These results suggest that descending excitatory volleys in the corticospinal motor tract during the motor preparation processes and peripheral motor unit activities in the reaction task are both separately excited by stress responses under pressure. Reaction times measured by EMG onset of the FDI were unchanged in accordance with corticospinal and EMG excitations under pressure, indicating generation of inefficient motor control energy for movement output.

Effects of psychological pressure on motor cortex excitability and EMG activity in a choice reaction task

Large cholinergic synaptic boutons named “C-terminals” contact the somata and proximal dendrites of motoneurons. In the spinal cord, C-terminals derive from cholinergic interneurons in the medial layer VII and regulate the motoneuron excitability via the activation of muscarinic receptors. We have previously identified that neurons in the magnocellular reticular formation in the medulla oblongata are the origins of the C-terminals in the hypoglossal nucleus, which is considered as the rostral extension of spinal motor columns. The projection patterns of the C-terminals are thus well conserved in the somatic motor neurons throughout spinal cord and caudal brainstem. In the cranial motor nuclei, the motoneurons that innervate skeletal muscles comprise two subtypes: branchiomotor and somatic motor neurons. The distinct differentiation between these two subtypes implies that the axonal projections and molecular profiles in the original neurons of the C-terminals are different in each subtype. However, the neural source of the C-terminals in branchiomotor nuclei remains unknown. To address this question, we explored the origin of the C-terminals in the branchiomotor nuclei by using the anterograde tract tracing techniques combined with immunohistochemistry of vesicular acetylcholine transporter as a specific marker for cholinergic terminals. After injections of biotinylated dextran amine (BDA) into the pontine, intermediate and gigantocellular reticular nuclei, double-labeled large terminals were observed in close apposition to the somata of motoneurons in the trigeminal and facial nuclei. These findings suggest that C-terminals in branchiomotor nuclei have similar organization of cells of origin to those in the somatic motor nuclei. We will also discuss the expression of the molecular markers of cholinergic neuron in the identified origins of the C-terminals.