Physiological parameters during repeated motor imagination

434 The main problem is the development of noninvasive techniques adapted to measure suitable parameters that tell us what is going on inside the central nervous system. One approach towards investigating the interconnections between functionally associated structures is to demonstrate eventrelated responses. In the light of the many physiological oscillations which can be observed, it is cycle time effects which are most relevant to psychophysiological research (for review see Spyer, 1981: Orlebe et al., 1985). It was the purpose of this study to determine the joint respiratory-cardiac cycle time effect of heart rate (HR) and blood pressure (BP) in spontaneously breathing anaesthetized dogs and investigate whether this effect is abnormal in dogs with hypertension. The responses were evoked by brief low-intensity electrical carotis sinus nerve stimulation (CSNS) triggered by the Rwave with an adjustable delay (O-210 ms) and applied in either inspiration or expiration. All baroreceptor afferent nerves were intact. The brief CNSN had no noticeable effect on breathing. The responses of means of HR. respiratory sinus arrhytmia (RSA) and respiratory blood pressure wave (RBPW) to CSNS were not different for normotensive and hypertensivedogs. There was no cardiac, but a small respiratory cycle time effect seen on HR and The magnitudes of RSA and RBPW were markedly enhanced in expiratory CSNS for all delays after the R-wave. Inspiratory CSNS was found to diminish the magnitudes of RSA and RBPW only when it was applied during the systole, and it produced no effect for longer delays. CSNS exerted a qualitatively identical effect on RBPW (syst.), RSA and RBPW (diast.), whereas the quantitative effects was less pronounced for RBPW (syst.) as compared to the latter two. In both respiratory phases, CSNS was increased at times of central presentation of the natural carotid baroreceptor discharges (120 ms and 70 ms after theR-wave, respectively). The present findings may be also relevant to interpreting responses evoked by sensory or somatic afferents. References

Orlebeke, J.F., Mulder, G. and van Doomen, L.J.P. (Eds.), Psychophysiology or Cardiovascular Control, Plenum Press. New York, 1985. Spyer KM. (1981) Neural organisation and control of the baroreceptor reflex. Rev. Physiol. Biochem. Pharmacol. 88: 23-124.

PHYSIOLOGICAL PARAMETERS DURING REPEATED MOTOR IMAGINATION Weiss, T., Beyer, L., Hansen, E., Wolf, A., Rost, R. Friedrick Schiller University, Institute of Physiology, GDR-6900 Jena Introduction

For many years we have been studying activation processes within c.n.s. by means of EEG, psychomotoric and vegetative parameters. In connection with these problems our laboratory deals with the research of neurophysiological laws of activating processes related to physical exercise (1) and the level of optimal activation. From a physiological point of view motor performances consist of two components: 1st - there are energetic and metabolic processes. 2nd - there are processes of information and motor control. Physiological mechanisms and laws of adaptation concerning the second component, that means the adaptation of central nervous information processing, require further extensive exploration. Adaptation processes of motor control and information processing may occur on the motivational level, on the sensomotoric level, within the activation system and in accordance with the vegetative-homeostatic level. Methods

Students (n = 8) who underwent systematically training in swimming were requested to imagine their own swimming movements at a distance of 100 m in their preferential style of swimming, sitting in a resting position, that means without any movement (motor imagination - MI). The supervisor signalized the beginning of the registration and the Ss could start by his own. Start and end were signaled by the Ss pressing a button. One series consisted of three periods of MI, 3 minutes rest between each MI-period. Heart rate (HR), skin conductance (SC), respiration rate and EEG were recorded before, during and after each period. Skin conductance was measured with electrodes placed on the second and third finger of the left hand. We registered the respiration cycle by means of a thermistor. The electrodes for the EEG pickup were of the Ag-AgCl type and were placed on the precentral and occipital region of the cortex contralaterally to handedness. EEG were analyzed by power density spectrum

435 with a NICOLET MED-80 computer. As condensed parameter we computed the mean frequency within the classical alpha-frequency range. The imagination-load data were evaluated in comparison with the pieimagination data. Results Heart rate increases from approximately 70 bests

per minute (bpm) at rest to 90 bpm in the average, in single cases up to 120 bpm. We can find the highest values of HR during the middle range of the imagination period. These enhanced values decrease after the end of the imagination period. HR during both resting periods between the single trials of imagination is still attenuated immediately after the end of imagination. In the middle third of the rest there is no difference compared with the resting level before the first imagination. All values during imagination are significantly enhanced in comparison with the resting level before start. Respiration cycle doubles during MI compared with breathing at rest. The imagined turns can be identified by single, longer periods of respiration. Considering the variation of duration of the respiration cycle, the lowest variability can be shown during the second MI period. The EEG shows a significant increase of the middle frequency within the alpha-range during the imagination periods and also during the time between MIperiods. These increases are significant at the 0.05 level. One can find a significant higher middle alphafrequency during the periods of imagination concerning pre-imagination periods and also during the second imagination concerning the fiit one. It is interesting, that the middle alpha-frequency of the occipital derivation increases during the imagination periods up to the third imagination period, whereas the highest alphafrequency level in the precentral area occurs during the second imagination. Conclusions

We found different changes of the examined parameters. These changes are similar to those of physiological correlates in other forms of mental performance. Especially the respiration cycle of swimmers seems to be in accordance with the real motor pattern. Our results confirm the opinion that there are different conditions for an effective imagination during first, second or third period of MI, whereas best conditions

in our investigation seem to be during the second period. During MI we assume the formation of a representational system - the functional system according to Anochin (2). Thus, the enhanced middle alpha-frequency of the EEG beginning with the first imagination during all following periods might be the result of the organization of a functional system to realize motor imaginations. In accordance with the model of Skinner (3) the cortex forms and controls in dependence on the future result of movement (result of behavior) a specific field of activation within the whole brain. Motor learning processes need such an “adequate state of activation” which must be prepared and controlled during exercise. References

L. Beyer et al.: The EEG as a parameter of central nervous activation during exercise. In this volume. P.K. Anochin: Beitraege zur allgemeinen Theorie des funktionellen Systems. Gustav Fischer, Jena 1978. J.E. Skinner: Central gating mechanisms that regulate event-related potentials and behavior. In: T. Ebert (Eds.): Self regulation of the brain and behavior. Springer, Berlin (West) 1984.

THE EFFECT OF HEMISPHERIC PREFERENCE AND HEMISPHERIC ACTIVATION ON HEARTBEAT PERCEPTION J. Weisz, L. Bahlzs, G. Adam Psychophysiological Research Group and Department of Comparative Physiology, Ecltvos Lorand University, Budapest, Hungary The purpose of this study was to investigate the influence of differential hemispheric activation and hemispheric preference on heartbeat discrimination accuracy. Hemispheric preference was determined on the basis of the predominant direction of the subject’s conjugate lateral eye movements (CLEMs) Each subject was assigned to a left-mover (leftward CLEMs>70%), a right-mover (leftward CLEMs<=30%), or a bidirectional (3O%