$4 Invited Lectures of motor control. After summarizing these reports briefly, 1 wish to focus this lecture on recent experimental findings using sub- human primates. Initially, neuronal activities in motor areas have been studied during performance of such simple motor tasks as those in reaction time tasks. The activity in secondary motor ar- eas appears similar to that in the primary motor area, suggesting that a population of neurons in multiple motor areas is active even though the motor task is simple. On the other hand, if motor tasks are more complicated and demanding, neuronal activities in individual areas appear different. The differences are particularly during sequential motor performance. SMA neurons were gener- ally more active while sequential motor tasks were performed on the basis of memory, whereas PM neurons were more active un- der visual guidance. Neurons in the presupplementary motor area (preSMA) exhibited more complex properties. Finally, I wish to introduce another aspect of area-specific neuronal activity that seems useful for programming or executing multiple movements in a predetermined order. • Electrodiagnosis in rehabilitation Ernest M. Johnson. The Ohio State University While for many years, Electrodiagnosis (EDX) has been used in determining the case of a variety of neuromuscular condition, it is not widely known that it has an important role to play in prognosis and management of these conditions. Examples: (1) Use of Compound Muscle Action Potential in assessing degree of weaknesses in Radiculopathy. After 5 days the distal segment of an injured axon will not respond if undergoing Wallerion Degeneration. On the other hand, if conduction block at root is present the CMAP will be near normal. (2) Chronology of abnormal membrane irritability in stroke. Fibrillation potentials and positive waves disappear as beginning spasticity or volitional function appear and thus assisting in reha- bilitation timing. (3) Similarly the presence of these abnormal potentials are seen in the spinal shock phase of tetraplegic spinal cord injured patients and their disappearance heralds the onset of spasticity -- helpful in management of the bladder. (4) In entrapments such as carpal tunnel syndrome, the ampli- tudes and duration of the action potential will be indications of the degree of axonal death or conduction block when stimulation is done proximal and distal to C'E This can be helpful in treatment plans. In summary, EDX done during the management of a variety of neuromuscular diseases will give helpful information to guide the clinician during the rehabilitation process. • Neurophysiology of preconscious and conscious mechanisms of the human brain J. Desmedt, C. Tomberg. Brain Research Unit, University of Brussels, Belgium Consciousness offers a major challenge to the neurosciences. While being subjective to the organism concerned, conscious func- tions reflect intrinsic biological processes of the brain and they add critical utility to behavior control, Because of their survival value, they developed through Darwinian natural selection over millions of years of animal evolution, from elementary levels to in- creasingly sophisticated efficiency. One question is whether brain neurophysiology in humans can pin down any features manifesting definite steps in conscious or uncoscious perceptual processing of simple sensory inputs. In somatic attention, short-latency cortical potentials evoked by a target finger stimulus can manifest poten- tiation of representations in primary parietal cortex. About 100 msec later, the dorsolateral prefrontal cortex discloses enhanced electrogeneses, probably reflecting activation of pertinent somatic representations in working memory. We found a functional "bind- ing" between these areas by showing a transient selective phase locking of 40 Hz oscillations (Neurosci. Lett. 1994, 168: 126-129). We believe such re-entrant interactions at 40 Hz through recipro- cal cortico-cortical connections to be an essential feature of the conscious brain mechanisms invoked for the identification of an object (in this example, a finger) and for the subsequent decision to release a motor behavioral response. The binding phenomenon antedates the P300 electrogenesis which is thought to reflect post- decision closure of the cognitive chunk (EEG clin. Neurophys- iol. 1979, 47: 648--670). The data suggest a meaningful functional organization along time of basic cognitive processes underlying conscious behavior. • Clinical implications of brain stem reflexes in man H.C. Hopf. Neurology Clinic, University of Mainz, Mainz, Germany, FRG Within the brain stem nuclei and tracts providing different func- tions are densely packed leaving very few 'silent' spots where le- sions will not cause noticeable impairment. Some clinical signs, e.g. ataxia and vertical gaze paresis or Horner's syndrome, are of little localizing value due to their broad or scattered intraaxial representation. Other signs, such as cranial nerve palsy, enable to refer a lesion to a difinite level. Brain stem reflexes are of com- plementary use since they are partly mediated by structures not accessible to physical examination. Electrophysiological examination of brain stem reflexes in the individual patient yields valuable information by (1) demonstrating involvement or sparing of clinically silent structures (e.g, trigeminal mesencephalic tract and nucleus), (2) proving simultaneous disorder of closely adjacent structures of different function (e.g. R1 blink reflex arc and medial longitu- dinal fasciculus), and (3) showing discordant involvement of reflexes running along identical structures for part of their loops (e.g. masseter myotatic and masseter inhibitory reflexes). The various brain stem reflexes have different topodiagnostic validity. The monosynaptic and oligosynaptic reflexes are the most reliable for localizing purposes (masseter, R1 blink, $1 masseter inhibitory reflexes). Their respective localizing domain applies to (a) the lateral lower pontine level for the R1 blink reflex, (b) the dorsal upper pontine and mesencephalic tegmentum for the masseter reflex, and (c) the lower pontine and ponto-medullary junction level for the $1 masseter inhibitory reflex. Simultaneous evaluation of the lower cranial nerve cortico-bulbar supply addi- tionally improves the topodiagnostic accuracy. I-~ The clinical and pathological dynamics of multiple sclerosis W.I. McDonald. National Hospital for Neurology and Neurosurgery, London WC1N 3BG, England A necessary pre-requisite for the development of rational treat- ment for multiple sclerosis is an understanding of the pathophysi- ology of functional loss. The serial application of NMR techniques (imaging and spectroscopy) to the study of multiple sclerosis has increased our understanding of the natural history of the new lesion and is beginning to give insights into the nature of older