H. G. J. M. Kuypers (1925–1989)

understanding the magnocellular cholinergic neurons in the basal forebrain include their rostrocaudal continuity and association with prominent fiber bundles. Current confusion with respect to the nomenclature of the cholinergic basal nuclear complex is obvious, and this appears to be due primarily to the chemoarchitectonic and hodological complexities of this part of the brain that have been revealed by recent advances in anatomical techniques. Understandably, such complexities have generated diverse views of basal forebrain organization. At this symposium, many of these views were presented and discussed in an attempt to view the cholinergic basal forebrain from different angles, including its relationship to major fiber bundles and efferent projections, its afferent connectivity, and crossspecies comparisons. General consensus on a number of points emerged from the oneday session. First, the distribution of basal forebrain cholinergic neurons does not observe classically defined anatomical boundaries. Second, the 'Ch' nomenclature applies best in primates

but, in the opinion of certain participants (e.g. FiNger, Semba), is not applicable and may even be misleading in other species in which the pertinent cell groups are not as extensively developed. Finally, forebrain cholinergic neurons have large radiating dendrites extending through passing fiber bundles, giving rise to the view that one key element in understanding their organization might be the association of those neurons with fiber bundles. Most participants agreed that these general considerations form the groundwork for a new beginning concerning the ways in which the organization and functions of the cholinergic basal nuclear complex might be addressed. Selected references 1 Meynert, T. (1872) in Handbuch der Lehre yon den Geweben, Zweiter Band (Stricker, S., ed.), pp. 694-808, Engelmann Verlag 2 Brockhaus, H. (1942) J. Psychol. Neurol. 51, 57-95 3 Bigl,V., Woolf, N. J. and Butcher, L. L. (1982) Brain Res. Bull. 8, 727-749 4 Butcher, L. L. and Woolf, N. J. (1984) in Handbook of Chemical Neuroanatomy, VoL 3: Classical Transmitters and Transmitter Receptors in the CN5, Part II (Bj6rklund, A., H6kfelt, T. and Kuhar, M. J., eds), pp.

1-50, ElsevierBiomedical Press 5 FiNger, H. C (1982) Brain Res. Rev 4, 327-388 6 Mesulam, M-M., Mufson, E J, Levey, A I and Wainer, B H (1983) J Comp Neurol 214, 170-197 7 Mesulam, M-M, Mufson, E J, Wainer, B. H and Levey, A I (1983) Neuroscience 10, 1185-1201 8 Price, J L and Stern, R (1983) Brain Res. 269, 352-356 9 Woolf, N J, Eckenstein, F and Butcher, L. L (1984) Brain Res Bull 13,751-784 10 Semba, K, Reiner, P B and Fibiger, H C (1988) J Comp Neurol 267, 433-453 11 Zaborszky, L in Central Cholinergic 5ynaptic Transmission (Frotscher, M and Misgeld, U, eds), Birkh~user (in

Acknowledgements Thissymposiumwas madepossibleby a grant from the AlzheimerSocietyof

Canada.

press) 12 Mesulam, M-M. and Geula, C. (1988) J. Comp. Neurol. 275, 216-240 13 Par4, D., Smith, Y., Parent, A. and Steriade, M. (1988) Neuroscience 25, 69-86

14 McGeer, P. t., McGeer, E. G., Fibiger, H. C. and Wickson, V. (1971) Brain Res. 35, 308--314 15 Talbot, K., Woolf, N. J. and Butcher, L. L. (1988) J. Comp. Neurol. 275, 580-603 16 Alheid, G F and Heimer, L (1988) Neuroscience 27, 1-39 17 de Olmos, J, Alheid, G F and Beltramino, C A (1985)in The RatNervous System, VoL I: Forebrain and Midbrain (Paxinos, G, ed), pp 223-334, Academic Press 18 Heimer, L, Alheid, G F and Zaborszky, L (1989) Neuroscience Year, Supple 1 pp 21-24, Birkh~user I.,,,=-=-,,--

..

'ans Kuypers, Professor and .Head of Anatomy at the Uni- tt. G. J. M. Kuypers (1915-1989) H versity of Cambridge, UK, died during the night of 25 September 1989. He appeared to have not been in pain. Hans Kuypers was one of the great men in neuroscience of the post-war years of this century. He was a scientist and an organizer of uncommon talent. He was prolific but not shallow. He saw what lines to follow where many did not; he had no pretence, where others had. He was a man of strong character, full of common sense. He was an observer and a raconteur of rare quality. Mrs Kuypers died twelve years ago; Hans Kuypers guided his six children into and in adulthood with uncommon devotion. When a man of great merit and warmth dies while he is still capable of giving, the knowledge that death is inevitable causes anger and grief. But anger and grief do not take one far and will themselves die, too. Below, I write a TINS, Vol. 12, No. 12, 1989

synopsis of Hans Kuypers' life. Hans Kuypers was born in 1925, obtained his MD in 1950 and his Phl) in 1952, both in Leiden (S. T. Bok and Walle J. H. Nauta were his thesis advisors). He trained for several years in neurology and emigrated to the USA where he was appointed assistant professor at the University of Maryland Medical School in Baltimore, MD. His career in the USA ended in 1966 when he was Professor of Anatomy at Case Western Reserve Medical School in Cleveland, OH. He assumed the Chair of Anatomy of the newly founded Erasmus University Medical School in Rotterdam, The Netherlands, and, in 1984, he became Professor of Anatomy and Head of the Department of Anatomy at the University of Cambridge, the place he truly loved. Wherever he worked, he worked hard, and everywhere he influenced and

guided young people and left deep traces. His curriculum vitae lists more than 120 full papers published between 1956 and 1989. Among his significant contributions are (1) the description of cortical projections to the somatosensory nuclei of termination 1, (2) the study of the postnatal development of corticospinal connections in the monkey2, (3) the dissection of cortical control of ipsi- and contralateral arms, hand and finger movements in the monkey3, (4) the demonstration of projections from basal forebrain and hypothalamus to cortex in the monkey4, (5) the analysis of the effects on visually guided reaching behaviour of ablations of premotor cortex in monkey 5, and (6) two technical innovations of great importance for systems neuroscience - the double-labelling technique 6, and, only recently, the use of viruses as transneuronal retrograde tracers.

© 1989,ElsevierSciencePublishersLtd,(UK) 0166-2236/89/S02.00

Hendrik Van der Loos Institute of Anatomy, Universityof Lausanne, 1005Lausanne, Switzerland.

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ation (ENA). He was ENA's third president. In a context well outside neuroscience, Oscar Niemeyer, the noted Brazilian architect, once summoned his fellows to aim at 'creating today the past of tomorrow'. Hans Kuypers, in his unpretentious way, attempted that. What is more, he was one of the few among us who succeeded. And thus, what he made remains. His children should find comfort in this. But now, and acutely, we feel the loss of the person we loved. I shall miss him badly.

Hans Kuypers. His paper, early this year in with G. Ugolini and P. L. Strick, on the latter subject 7, is already having some impact. From the early 1960s until his death Hans Kuypers deepened his insight into the organization of the motor system; he had become one of its foremost students.

Science,

Hans Kuypers was a member of the Royal Dutch Academy of Sciences and, after his appointment to the Cambridge Chair, was elected Fellow of the Royal Society. He was founding member of the European Brain and Behaviour Society (EBBS) and of the European Neuroscience Associ-

References 1 Kuypers, H. G. J. M. (1958) Science 128, 662-663 2 Kuypers, H. G. J. M. (1962) Science 138, 678-680 3 Brinkman, J. and Kuypers, H. G. J. M. (1973) Brain 96, 653-674 4 Kievit, J. and Kuypers, H. G. J. M. (1975) Science 187, 660-662 5 Moll, J. and Kuypers,H. G. J. M. (1977) Science 198, 317-319 6 Van de Kooy, D., Kuypers,H. G. J. M. and Catsman-Berrevoets,C. E. (1978) Brain Res. 158, 189-196 7 Ugolini, G., Kuypers, H. G. J. M. and Strick, P. L. (1989) Science 243, 89-91

Trendsin confocalmicroscopy T. Wilson T. Wilsonisat the Confocal microscopy is a relatively new technique that permits us to Departmentof obtain high-resolution images of very thin sections of a specimen. EngineeringScience, This unique optical sectioning property, together with a suitable Universityof Oxford, computer, allows us to image structures in three dimensions. This ParksRoad,Oxford review describes the factors that affect the strength of this optical OX13PJ,UK. sectioning and points out some of the/imitations of the technique. Other convenient methods of imaging in scanning optical microscopes are described and new areas of promising research are highlighted. Scanning optical microscopy in general and confocal microscopy in particular have reached a state of quasi-maturity in the sense that a number of commercial instruments are now available. Therefore, it is timely to pause and review the advantages and limitations of these instruments. It is also appropriate to try to predict the directions that future developments might follow. In attempting the latter I shall write from the point of view of the physicist and limit my remarks to the opportunities for and limitations on optical image formation. (See Ref. 1 for a review of the applications of these techniques to problems in neurobiology.) The basic principles of a confocal microscope are shown in Fig. 1. The only difference between confocal and conventional scanning systems is the presence of a point detector in the confocal case2'3. 486

This allows us to express the intensity image of a thin object of amplitude transmittance or reflectance, t, as / = Ih 2 6) tl 2

(1)

where the symbol (~) denotes the convolution operation. The function h is basically the diffractionlimited focal spot (the Airy disc) of the objective lens; h is called the amplitude point response function and is related mathematically (via a Fourier transform) to the shape of the objective lens pupil (its pupil function). This property results in an improvement in lateral resolution. Arguments based on spatial frequencies say that the resolution in confocal as opposed to conventional systems is improved by a factor of two. Important as this is, it is probably its action with respect to depth of focus that has made the confocal instrument so attractive and useful. The principle is illustrated in Fig. 2. The presence of the limiting point detector ensures that we image detail only from the region around the focal plane. This property of depth discrimination can be conveniently measured by scanning a perfect reflector through focus and using the full-width half-intensity of the resulting profile to measure the strength of the sectioning. Figure 3 shows how this varies with the numerical aperture of the objective

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TINS, VOI. 12, NO. 12, 1989