P36-17 Cerebral preparation of natural movements: an EEG study

29th International Congress of Clinical Neurophysiology S321

P36-15Improved bereitschaftspotential (BP) in Parkinson’s disease (PD)by means of neuro-feedback (NFB) training of slow corticalpotentials (SCPs)

T. Fumuro1, M. Matsuhashi2, T. Mitsueda1,3, M. Inouchi1, R. Matsumoto1,J. Kawamata1, H. Inoue1, R. Takahashi1, A. Ikeda1

1Department of Neurology, Kyoto University Hospital, Kyoto, Japan,2Human Brain Research Center, Kyoto University Graduate School ofMedicine, Kyoto, Japan, 3Department of Neurology, Otsu Red CrossHospital, Shiga, Japan

Objective: Early component of BP (early BP) was smaller in PD patientsthan in healthy volunteers whereas its late component (late BP) ratherincreased. We previously reported that once young healthy volunteerswell learned to control their SCPs by means of NFB, they could increaseearly BP amplitude during self-regulated negative SCPs performance(Fumuro et al., 2006, in Japanese). We investigated the effects of self-regulation of SCPs on BP amplitude in PD patients and aged healthyvolunteers.Methods: 7 PD patients and 9 healthy volunteers were recruited. 5electrodes were fixed on the scalp (C3, C1, Cz, C2 and C4). BP was firstlyrecorded for self-paced, button-press by the right thumb about every10 sec (BP1). It was followed by NFB training where subjects trainedhimself for self-regulation of SCPs of Cz for 20 to 50 min. The 2nd BP wasrecorded while self-regulated negative SCPs was performed (BP2). Thewhole set was done in one day and was repeated 2 to 4 times on differentdays. BP1 and BP2 were compared between the two groups depending onthe degree of NFB performance (good trials vs poor trials).Results: Good trial sessions had larger early BP in BP2 than that in BP1whereas poor trial sessions had smaller early BP in BP2 than that in BP1. Incontrast, late BP showed no difference between BP1 and BP2 regardlessthe degree of NFB performance. It was commonly seen in both PD patientsand healthy volunteers.Conclusions: Good NFB performance of negativation could increase EPSPof pyramidal cells for early BP generation in PD patients and healthyvolunteers.Significance: NFB could enhance the excitability of cortices related tovoluntary movement preparation, and a further investigation will bewarranted for improvement of motor function of PD in relation to theBP enhancement.

P36-16Event related desynchronization of subthalamic nucleus activitiesprior to volitional movement termination in patients with Parkinsondisease

C.-H. Tsai1,4, T.-F. Chien2, H.-Y. Lai2, Y.-T. Hsu1, Y.-Y. Chen2,S.-M. Chiou3

1Department of Neurology, China Medical University Hospital, Taiwan,2Department of Electrical Engineering, National Chiao-Tung University,Taiwan, 3Department of Neurosurgery, China Medical UniversityHospital, Taiwan, 4Graduate Institute of Neural and Cognitive Sciences,Taiwan

Objective: The subthalamic nucleus (STN) activities play an importantrole for the cortical-basal ganglia circuitry, which were associated withthe feedforward organization of the volitional movement initiation. HowSTN implicates in movement termination is uncertain. The current studyinvestigates the pre-termination activities of the STN during phasic andtonic wrist extension movements in patients with advanced Parkinsondisease (PD) after deep brain stimulation.Methods: Ten patients with Parkinson disease (five females; mean±SEMage 63.2±9.7 years, disease duration 5.25±2.1 years) were recruited forthe study on the 4th day after deep brain stimulation. The automaticburst detection method was adopted to determine the initiation andtermination points of volitional EMG burst. The local field potentials(LFPs) of STN were analyzed by time frequency (TF) analysis. The TFanalysis presented response both in time and frequency domain. Thealgorithm used in this experiment was power spectra with 1024 frequencyresolutions. Spectra were estimated by calculating median across sectionsand block sections were shifted by stationary data points until the wholesequence had been analyzed.Results: Averaged movement duration is 0.96±0.40 sec in the phasicmovement and 9.19±3.63 sec in the tonic movement. The results showevent-related desynchronization (ERD) at the frequencies from 10 to40 Hz. The decrease of power percentage commenced earlier, at the2-second point prior to movement termination, and greater in phasic

movement as compared with the tonic one. The main difference of powerpercentage between the 2 groups is over 50% from 0.8 second to 0 secondbefore movement termination.Conclusion: The findings implicate that the 10 to 40 Hz local fieldpotentials (LFPs) of STN plays a crucial feedforward role in movementtermination and the role may be modulated by different types ofvolitional movements.

P36-17Cerebral preparation of natural movements: an EEG study

E. Houdayer1, R. Kayal1, J. Chu1, M. Hallett1

1Human Motor Control Section, NINDS, NIH, Bethesda, USA

Objective: To investigate whether cerebral activity related to naturalmovements, without any previous instruction, is similar to activityobserved before self-paced, ‘instructed’ movements.Methods: Twelve healthy volunteers were recruited. Subjects were toldthat the purpose of the study was to record natural flow of brainand muscles. They stayed seated in an armchair for one hour andreceived no instructions except not to fall asleep. They were notallowed to use any external device to entertain themselves. Threesubjects were also told to perform self-paced right wrist extensions.Electroencephalographic (EEG) activity was recorded with 32 scalpelectrodes. Electromyographic (EMG) activity of several arms and legsmuscles was recorded bilaterally. Bereitschaftspotential (BP) as well asmu and beta event-related desynchronizations (ERD) were calculated off-line, in relation to movement onset.Results: Two subjects did not move. The ten others moved arms andlegs freely. One had no BP or ERD preceding his movements. For the9 others, a BP and mu or beta ERD preceded the natural movements.They were located over sensorimotor areas, bilaterally and maximal overmedial electrodes (most of movements were bilateral). BP and ERD onsetwas similar to the ‘instructed’ condition. However, BPs preceding naturalmovements were spread in more frontal areas compared to the instructedcondition in which they were more parietal.Conclusions: Our results show that ‘natural’ movements are precededby BP and ERD similar to the ones observed in ‘instructed’ conditions.Interestingly, the latencies of BP or ERD in ‘natural’ or ‘instructed’conditions were very similar. This result confirms that the brain activitystarts to prepare the motor plan far in advance compared to themovement onset. The difference of localization might be due to adifference in motor planning, since the instructed movements might havebeen generated more automatically.

P36-18Scalp topography of sniffing-related cortical potentials

B. Koritnik1, D. Jeran1, I. Zidar1, A. Belic2, M. Korosec1, J. Zidar1

1Institute of Clinical Neurophysiology, University Medical CentreLjubljana, Ljubljana, Slovenia, 2Faculty of Electrical Engineering,University of Ljubljana, Slovenia

Objective: A possible way to study the neural mechanisms for the controlof voluntary breathing is through respiratory manoeuvres such as sniffing.Cortical potentials associated with voluntary movement can be recordedduring self-paced inspiratory manoeuvres. Our aim was to describe thescalp distribution of sniffing-related cortical potentials (SRCP) and todistinguish various subcomponents of SRCP.Methods: Ten healthy subjects participated in the study. They wereperforming self-paced voluntary sniffs with submaximal intensity. EEGwas recorded using a 32-electrode cap. Nasal pressure changes were usedto average the EEG signal. Epochs starting 2.5 s before and ending 1 safter the sniff onset were analysed. Principal component analysis (PCA)was performed in three different time intervals, corresponding to theBereitschaftspotential (BP; 1.5 to 0.5 s), negative slope (NS; 0.5 to0.1 s) and motor potential (MP; 0.1 to +0.1 s).

Results: During BP, the strongest PCA component represented a radiallyoriented dipole located approximately at the vertex. It was increasing instrength. The second component suggested a tangential bilateral dipolein the fronto-parietal direction with a variable time course. During NS,the strongest component was radial and centrally oriented as well. Thetangential component during NS was similar to BP but more pronounced.Both components were increasing in strength during the interval. DuringMP, the only unequivocal component was tangential, located bilaterallyover the motor cortex, with a rising time course.