[Remembering an amnesic patient (and half a century of memory research)]. / Erinnerung an einen Amnestiker (und ein halbes Jahrhundert Gedächtnisforschung).

The development of memory research is inextricably bound to the fate of patient HM. On the occasion of his death, the circumstances are remembered, which lead to the bilateral removal of parts of his medio-temporal cortex in 1953. And the importance of the subsequent more than a half-century of research about his postoperative amnesic deficits as well as remaining learning and memory functions are outlined. The early reports triggered improved animal research which together with parallel investigations on HM and patients with similar deficits eventually lead to the downfall of the up until then dominating antilocalisationist view of brain functions. This was the result of having convincingly shown that memory could be severely impaired without major changes in other cognitive functions. Later investigations lead to question the unity of memory itself and forced a more and more differentiated description of different kinds of memory and their associations with separate neuroanatomical structures. A simplified summary of the resulting recent ideas of declarative memory systems is presented together with an outline of connections to their supporting medio-temporal, diencephalic and frontal-cortical structures. Finally, an attempt is made to address the question about the impact on the person HM of not having been able to form consciously retrievable memories from age 27 until his death at age of 82, thus having to rely for a reconstruction of his life on memories from child- and young adulthood as well as single momentary short-lived experiences.

Functional architecture of the mystacial vibrissae.

We investigated the transduction operation and function of the mystacial vibrissae, using a comparative morphological analysis and behavioral experiments in rats. Vibrissal architecture was documented in a series of mammals to identify evolutionary conserved features of vibrissal organization. As a result of this analysis, we distinguish between a frontal microvibrissal system and macrovibrissal system of the mystacial pad. The latter was invariably comprised of whiskers aligned in regular rows. In each row, whiskers were oriented perpendicular to the animal's rostrocaudal axis; all shared a specific dorsoventral orientation. In all species, progressing from rostral to caudal in any vibrissal row, there was a precisely exponential increase in whisker length. Each whisker appeared to act as a lever-like transducer, providing information as to whether or not--but not where--an individual vibrissa had been deflected. The rat's frontal microvibrissae system was found to have a vibrissa tip density that was about 40 times higher than that of the mystacial macrovibrissae. In behavioral studies spatial tasks and object recognition tasks were used to investigate (a) search behaviors; (b) single whisker movements; (c) object recognition ability; and (d) effects of selective macro- or microvibrissae removal on task performances. A clear distinction between the functional roles of macro- and microvibrissae was demonstrated in these studies. Mystacial macrovibrissae were critically involved in spatial tasks, but were not essential for object recognition. Microvibrissae were critically involved in object recognition tasks, but were not essential for spatial tasks. A synthesis of these morphological and behavioral data led to the following functional concept: The mystacial macrovibrissae row is a distance decoder. Its function is to derive head centered obstacle/opening contours at the various dorsoventral angles represented by vibrissal rows. This distance detector model is functionally very different from traditional concepts of whisker function, in which the mystacial whiskers were hypothesized to form a fine grain skin-like object-recognizing tactile surface.

Establishing clinical neuropsychology in Germany: scientific, professional, political, and legal issues.

German psychologists may have been first to establish a university curriculum in psychology with the expressed purpose to provide--after its successful completion--a certificate of professional qualification. This "Diplom-Prüfungsordnung" (Diploma Examination Regulation) was accepted nationwide in 1941. However, it took over fifty more years before some progress toward the political and legal acceptance of autonomous clinical activities of psychologists was made. Legislation to secure these advances is still pending. In this context the efforts to establish the profession of clinical neuropsychology are described and discussed within the historical development of professional psychology in Germany with special emphasis on the problems of compromises within the force fields of science and professional politics. Finally, the postgraduate training as well as the certification and accreditation procedures developed by the Gesellschaft für Neuropsychologie, the Society of German-speaking neuropsychologists, are presented.

Incomplete split-brain syndrome in a patient with chronic Marchiafava-Bignami disease.

A 40-year-old male patient is presented who survived Marchiafava-Bignami disease and recovered sufficiently to be assessed neurologically and neuropsychologically in some detail. Besides dementia, lack of initiative, and psychomotor retardation here ascribed to extracallosal damage, he showed a number of symptoms of hemispheric disconnection such as left-sided apraxia, poor bimanual coordination in specific laboratory tests, and deficits in the interhemispheric transfer of somaesthetic information. Other commissural functions, such as interhemispheric transfer of tactile, visual and auditory information as well as bilateral coordination in previously overlearned tasks, were nearly intact. The observed dysarthria could be meaningfully discussed in relationship to postcallosotomy mutism. It is concluded, that the partial interhemispheric disconnection syndrome in Marchiafava-Bignami disease lacks functional compensation which is different from the usual course in partial commissural section.

Cortical and subcortical afferent connections of the primate's temporal pole: a study of rhesus monkeys, squirrel monkeys, and marmosets.

The afferent connections of the primate's temporopolar cortex were investigated with the retrograde horseradish peroxidase technique. Old World and New World monkeys received small unilateral injections of horseradish peroxidase. These labeled cells in a number of cortical, thalamic, and brainstem regions and in a few further telencephalic and diencephalic regions. Cortically, the neighboring areas of the inferior and superior temporal gyrus and the insula contained a considerable number of labeled cells. Furthermore, a substantial projection arose from the orbitofrontal and the frontopolar cortex. The cingulate gyrus contained only very few labeled cells. Interhemispherically, corticocortical connections arose mainly from temporal lobe areas. Labeled cells were seen in various regions of the basal forebrain and cells labeled only faintly in the lateral and basal accessory nuclei of the amygdala. The claustrum contained labeled neurons only in one rhesus monkey. On the diencephalic level, the caudal medial portion of the medial pulvinar was the principal thalamic source of afferents to the temporopolar cortex. Furthermore, labeled cells were found in the neighboring, caudal part of the mediodorsal nucleus, within and along the nucleus limitans, in the medial geniculate nucleus, and in several nuclei of the nonspecific system. The fields of Forel, the zona incerta, and lateral and dorsomedial hypothalamic areas contained a few labeled cells. Within the brainstem of the rhesus monkeys those regions projecting diffusely to the cortex contained a few labeled neurons. Furthermore, these brains had some labeled cells in the regions of the nuclei medialis annuli aqueductus, tractus mesencephalicus nervi trigemini, and trochlearis. Although among the three species differences in the cortical and thalamic projection patterns were observed, the regions projecting most densely to the temporal pole were similar in principle. This statement holds in particular for cortical and thalamic sites. However, the greatest number of labeled cells was found in the rhesus monkey, a fact that cannot be attributed solely to the size of the horseradish peroxidase injections and the size of the brain, but that appears rather to represent a true species difference. From our results we conclude that the temporopolar cortex constitutes a cortical area necessary for effective affectional-sensory integration.