Hans-Lukas Teuber

Further analysis of the hippocampal amnesic syndrome: 14-year follow-up study of H.M. ☆

Abstract The report attempts to delineate certain residual learning capacities of H.M., a young man who became amnesic in 1953 following a bilateral removal in the hippocampal zone. In addition to being able to acquire new motor skills (C ORKIN [2]), this patient shows some evidence of perceptual learning. He also achieves some retention of very simple visual and tactual mazes in which the sequence of required turns is short enough to fit into his immediate memory span; even then, the rate of acquisition is extremely slow. These vestigial abilies, which have their occasional parallels in the patients everyday life, are assessed against the background of his continuing profound amnesia for most on-going events, an amnesia that persists in spite of above-average intelligence and superior performance on many perceptual tasks.

The Riddle of Frontal Lobe Function in Man

This paper records a recurrent perplexity and a recent attempt at its resolution. Let me begin with the perplexity. Man_s frontal lobes have always presented problems that seemed to exceed those encountered in studying other regions of his brain. In striving to give a functional interpretation of anatomic pattern, we have therefore tended, in our laboratory, to begin by considering the occipital lobes and their processing of visual information (Teuber and Bender 1949; Teuber et al. 1960), and to progress from there to analysis of parietal and temporal lobe syndromes involving touch and hearing and higher processes (Teuber et al. 1951; Semmes et al. 1960). In this way, one can spend one’s life as an investigator without ever crossing the central fissure. And well one might—because it appears that by starting at the posterior end of the brain, it may become impossible in principle to reach the frontal lobes. I now believe that analysis of frontal lobe functions requires that we begin from that end, considering how these anterior parts act upon posterior, and predominantly sensory structures. What is needed is a 180° turn (Teuber 1961b). It is hardly an accident that the frontal lobes have continued to pose such insuperable difficulties to interpretations in traditional stimulus-response terms. Such conventional attacks on the problem go from sensory to motor functions; if the opposite approach is required—going from motor to sensory, as we shall suggest—then it may become understandable why frontal symptoms have been so perplexing.

Mirror movements after childhood hemiparesis

Mirror movements are normal in childhood and may persist to a later age following early brain lesions. We studied these movements in patients with childhood hemiparesis at different ages. The earlier the lesions, the more the mirror movements persisted. More mirror movement persisted in the nonparetic hand than in the pareticone. Complete paralysis of either hand tended to abolish all mirror movements in both hands. The task eliciting the most mirror movement was one that may come under ipsilateral control following contralateral damage. The greater persistence of mirror movements after earlier lesions appears to be an indicator of more extensive compensatory motor system reorganization that takes place after damage to a less mature nervous system.

Alterations in auditory fusion thresholds after cerebral injury in man

Abstract Patients with penetrating wounds of the left cerebral hemisphere have abnormal fusion thresholds for dichotically presented clicks even if tested 20 years after the trauma. At temporal separations at which normal listeners report two clicks, these patients report hearing a single click. This diminished temporal resolving power of patients with left posterior cerebral lesions is most pronounced in those who are deemed dysphasic.

Persistent anterograde amnesia after stab wound of the basal brain

Abstract A case of anterograde amnesia is described in which the memory disorder resulted from a stab wound of the basal brain, a fencing foil having entered the brain through the right nostril, taking a slightly oblique course to the left. Follow-up studies over seven years revealed a persistent paralysis of upward gaze, as the only definite neurologic sign, together with an anterograde amnesia in which verbal material was more affected than nonverbal. Perception and vigilance were intact. There were no seizures or seizure-equivalents, and in this respect the patients condition differed from that of H.M., the original case of anterograde amnesia after bilateral hippocampectomy described by S COVILLE and M ILNER . The stab wound in the present case appears to have involved the rostral midbrain. It is therefore of particular interest that the anterograde amnesia was combined with impotence and profound unresponsiveness to pain.

JUDGMENT OF VISUAL AND POSTURAL VERTICAL BY PARKINSONIAN PATIENTS.

IN THE PAST, disorders of the basal ganglia in man have been thought to produce symptoms limited to the motor sphere.1-3 It is conceivable, however, that parkinsonism might also lead to changes in perception. We suspected specifically that patients with parkinsonism might display an abnormality of interaction between posture and distance receptors. Such disturbances would be similar to those found after injury to the human frontal lobes.4 This prediction is consistent with the view that traditional categorization of cerebral function as purely motor or purely sensory might not apply to the basal ganglia and to similar intercalated structures. The prediction is also derived from the finding that certain behavioral changes, such as the delayed-response deficit in subhuman primates, can be seen in equivalent form after striatal lesions, and not only after frontocortical removals.E--7 Moreover, there is increasing evidence of massive influx from many sense modalities into the basal ganglia.s.9 Lastly, there are experiments suggesting that stimulation of the basal ganglia might be capable of modulating sensory input received in sensory cortical projection fields;l0-12 although some of these effects have been imputed to stimulation of internal capsule.13 A role of the basal ganglia in certain aspects of perception was suggested earlier in a study by Teuber and Mi~hkin .~ They tested men with penetrating gunshot wounds of either anterior or posterior thirds of the brain on several variations of a task designed by Aubert14 and discussed by Bender and Jung.lj This task requires a subject to judge the orientation of a luminous line in the dark under various conditions of body tilt. Patients with frontal-lobe injury made large errors in adjusting such a luminous line when their heads and bodies were tilted. In fact, errors after frontal injury were significantly greater than those after injuries to the posterior third of the brain, or in normal controls. Teuber and Mishkin4 considered the possibility that this phenomenon did not derive exclusively from lesions of the frontal cortex; in some of their cases, the symptoms could have arisen from coincident damage to the basal ganglia. We therefore decided to investigate whether basal ganglia disease might produce abnormalities similar to those found after penetrating trauma of the convexity of man’s frontal lobes.

Behaviour after cerebral lesions in children and adults.

Animal experiments tend to show that brain injuries sustained early in life have less effect than comparable lesions incurred at later stages. By contrast, neurological observations suggest that certain forms of early brain damage in children may have disproportionately serious consequences for later development. The apparent contradiction may be resolved if one grants that results might differ, according to (a) the kind of task employed, and (b) the age at which the child is tested. Three perceptual tasks have been devised which disclose such differential effects.

Crossmodal transfer of shape discrimination by children

Abstract Forty-eight children between the ages of 3 and 6 were given a shape-discrimination task which required them to recognize shapes presented visually or haptically. Recognition was either through the same modality (visual to visual, or haptic to haptic), or across sense modalities (visual to haptic, or haptic to visual). Under the conditions of this experiment, all age groups showed crossmodal transfer. Recognition across modalities was harder than in the visual-to-visual mode, but easier than in the haptic-to-haptic mode.

Levels of impairment of sensori-motor functions in children with early brain damage

Abstract Sixty-three ambulatory, educable children with early brain damage were tested neurologically, with the WISC, and with supplementary sonsory and perceptual tasks derived from studies of cases of late brain injury. Performance on these latter tasks was also assessed in normal children over a wide range of ages. Early damage seemed to spare elementary sensory function while motor impairment was conspicuous, particularly impairment of the oculomotor system, and the latter correlated with dificient performance on spatial tasks. Performance on a variety of verbal and non-verbal tasks correlated with lateralization of symptoms in the brain-damaged group; a reciprocal pattern emerged depending upon whether the right or left side of their body was predominantly involved. The results suggest that the adult pattern of hemispheric specialization antedates birth and that damage which does not encroach directly on the language zones leaves that pattern intact if somewhat attenuated, particularly in the case of left hemisphere functions. There were in the group of 63 only 12 with right-sided (left hemisphere) neurological signs and only 3 of these were dysphasic. This inequality of lateralizing signs could reflect a sampling bias (childred with right-sided signs may be more language impaired and less “educable”) or some greater invulnerability of the left hemisphere to early damage.

Visual field defects after missile injuries to the geniculo-striate pathway in man

SummaryVisual fields (defined by detection thresholds for moving and stationary targets) were examined in 10 cases of homonymous field defects due to retrochiasmal lesions. Using the Tübingen Perimeter, results of multiple perimetric methods could be compared quantitatively at identical retinal areas. The principal finding was one of thorough-going association of deficits: no instances of selective impairment of motion detection, flicker resolution, or regional dark adaptation were encountered. Pupillary reactivity to low-intensity light was depressed in areas of homonymous scotoma, as long as care was taken to avoid stimulation of relatively more intact regions of the visual field by scattered light. In the only case showing extreme difficulties in visual recognition (“agnosia”) for faces and objects there were unusually severe reductions in differential light detection thresholds, and in all other “elementary” visual functions. One half of the cases showed small homonymous scotomata with a sharp decrease of light sensitivity. They were often located in a perifoveal region that was otherwise normal. Field defects bordering on the midvertical meridian followed this meridian closer and tended to have steeper borders than those bordering on the midhorizontal meridian. Sparing of foveal vision (averaging 1.5°) was the rule but the spared region had reduced sensitivity. “Splitting” of the fovea was found in one case. Incongruence of homonymous field defects was greater for peripheral defects than for those near the center of the field; usually nasal fields showed larger defects than temporal. This tendency was enhanced by the sparing of parts of the monocular crescent in three cases.