Research and Occupation

Based on 14 years of clinical education and experience in the field of neurology my main interest has always focussed on clinical neurophysiologic examinations, especially electromyography (EMG) and evoked potentials (EP), but also the other techniques like electroencephalography (EEG), electrooculography (EOG), electroretinography (ERG) and Doppler sonography as well as colour-velocity coded duplex sonography.

My research activities during the years 1989-1993 concentrated mainly on transcranial magnetic stimulation (TMS), and they yielded some international publications on the muscular silent period elicited by cortical stimulation. I examined the physiological details and applied the method to the diagnosis of Parkinson's disease, cerebrovascular disease and patients under neuroleptic treatment. In 1993-1994 I devoted myself to visual psychophysics, the examination of physiological phenomena of perception and signal processing studied by means of threshold determination. This implies the exposure of normal subjects and patients to visual stimuli of an intensity close to perception thresholds of colour contrast, luminance contrast or motion in all its varieties (speed, amplitude, constancy, randomness).

   View of Mount Fuji from
   lake Ashinoko (Japan).
In 1995 and 1996 I met the challenging opportunity to spent 21 months in Prof. Shibasaki's laboratory as a guest scientist at Kyoto University. In that laboratory I was allowed to conduct extensive examinations into visual evoked potentials and fields (VEP and VEF) using a newly acquired Neuromag 122-channel planar gradiometer (GIF file 20 kB) to measure the minute magnetic fields which are elicited by the small currents within active nerve and ganglion cells. The magnetoencephalography (MEG) proved to be a very promising method to re-evaluate previous concepts of central processing of visual information. An example of the dipole analysis for an equivalent current source of the brain responses to a visual "on and off" stimulus of a black-and-white checkerboard pattern is given in another GIF image (26 kB). My studies encompassed different pattern stimuli defined by luminance or colour contrast, and special stimuli for visual motion perception and saccadic eye movements, which were created on a Cambridge Research Systems stimulator. The complete project would not have been carried out successfully without the manifold help and collaboration of my co-workers in that department, of whom my special thanks go to Drs. Takashi Nagamine, Xiaoping Xu and Shogo Yazawa, and of course the head of the department, Professor H. Shibasaki, who provided generous support in every aspect of life and research in Japan.

   Sample stimuli for pattern
   visual evoked responses.
At the moment, back in Germany, I have no direct access to magnetoencephalography, but I am currently gaining some practical experience with functional magnetic resonance imaging (fMRI). This method is an ideal complement to magnetoencephalography and helps to work up some findings, which could not be completely explained by MEG alone. The example shows the small brain region (red) activated by visual rotatory motion stimuli, which is located in the border region between temporal, parietal and occipital cortex, with exact reference to the anatomical structures depicted by MRI tomography (GIF image 41 kB).

Above all, it should be mentioned that most part of my daily activities is devoted to the care of patients from our wards, from other departments or from outside in need of specialist consultation. Unlike the first impression, which might come up by reading the above, I am not the one who would carelessly submit patients to high-tech medicine. The junior colleagues, who were taught by me, will confirm that the majority of diagnostic and therapeutic decisions is based on a thourough clinical interview and examination.

Bernhard Haug