Internal mammary veins: classification and surgical use in free-tissue transfer

The internal mammary artery has been well-investigated due to its frequent use in cardiac surgery. However, in reconstructive microsurgery in the thoracic region, the internal mammary vessels have been used rarely as recipient vessels, due to difficulties and lack of knowledge about the internal mammary veins. This study was designed to investigate the anatomy and topography of the veins. Its goal was to gain sufficient information about their availability in free-tissue transfer. Dissection of the vessels was performed in 86 cadavers bilaterally to the sternum. At the level of the fourth rib, which is the most desired access for microvascular anastomosis in reconstructive breast surgery with free flaps, the veins were found to be adequately large (range 0.64 to 4.45 mm). Results were in close agreement with 100 bilateral measurements obtained by color Doppler sonography in 16 patients preoperatively, and additionally in 34 healthy volunteers. Preoperative detection of vessels with the aid of sonography facilitated planning of surgical procedures. According to these findings, the internal mammary veins may be used as suitable recipient veins for free microvascular tissue transfer, especially for established autologous breast reconstruction with the free transverse rectus abdominis myocutaneous flap, or for reconstruction of complex thoracic-wall defects.

[Spontaneous pregnancy after ligation of the uterine artery]

In this case report, the functional anastomoses of the uterine arteries are demonstrated. In our opinion, the selective ligation of one or both uterine arteries is the method of choice for treating severe gynaecological or obstetrical bleeding complications. Successful haemostasis and preservation of the uterus can be achieved permitting future spontaneous pregnancies.

The special role of distant structures in perceived object velocity

How do we judge an object's velocity when we ourselves are moving? Subjects compared the velocity of a moving object before and during simulated ego-motion. The simulation consisted of moving the visible environment relative to the subject's eye in precisely the way that a static environment would move relative to the eye if the subject had moved. The ensuing motion of the background on the screen influenced the perceived target velocity. We found that the motion of the "most distant structure" largely determined the influence of the moving background. Relying on retinal motion relative to that of distant structures is usually a reliable method for accounting for rotations of the eye. It provides an estimate of the object's movement, relative to the observer. This strategy for judging object motion has the advantage that it does not require metric information on depth or detailed knowledge of one's own motion.

Size illusion influences how we lift but not how we grasp an object

Reaching out for an object is often described as consisting of two components that are based on different visual information. Information on the object's position and orientation guides the hand to the object, while information on the object's shape and size determines how the fingers move relative to the thumb to grasp it. We propose an alternative description, which consists of determining suitable positions on the object-on the basis of its shape, surface texture, and so on- and then moving one's thumb and fingers to these positions. This could lead to the same performance without requiring distinct visual information on the object's orientation or size. If so, an illusory change in size need not influence the distance between thumb and fingers when reaching out for an object. However, as the object's size is used to estimate its weight, the illusory change in size should influence the force that is exerted to lift the object. To find out whether this is so, eight subjects were asked to pick up brass disks from a fixed position straight in front of them. The illusory change in size was brought about by presenting five converging lines in two different configurations under the disks. As predicted, the illusion influenced the force used to lift the disks, but not the distance between the subjects' thumbs and fingers when reaching for the disks.

Is judging time-to-contact based on 'tau'?

An investigation was undertaken into whether judgments of time-to-contact between a laterally moving object and a bar are based on the direct perception of an optical variable (tau), or on the ratio between the perceived distance and perceived velocity of the object. A moving background was used to induce changes in the perceived velocities without changing the optical variables that specify time-to-contact. Background motion induced large systematic errors in the estimated time-to-contact. It is concluded that the judgment of time-to-contact is primarily based on the ratio between the perceived distance and the perceived velocity, and not on tau.

Perceived motion in depth

We examine how various sources of information contribute to the percept of motion in depth. Subjects were presented with targets moving in depth, and were asked to judge their velocities and final positions. On each presentation, the target's position relative to the two eyes (target vergence), the size of the target's retinal image and the difference in this image's position relative to that of the background in the two eyes (relative disparity), each either changed as they normally would for a target moving at a fixed speed towards the observer, or did not change at all. Subjects' judgements for various such combinations show that all three sources of information influence both the perceived velocity of motion in depth and the final perceived position, but in different ways. This is not too surprising, because the assumptions that the use of each source of information are based on, are different for the two tasks. We propose that the way the different sources are combined is governed by the likelihood of the assumptions, that are required to use that information, being true under the given circumstances.

Prediction of a moving target's position in fast goal-directed action

Subjects made fast goal-directed arm movements towards moving targets. In some cases, the perceived direction of target motion was manipulated by moving the background. By comparing the trajectories towards moving targets with those towards static targets, we determined the position towards which subjects were aiming at movement onset. We showed that this position was an extrapolation in the target's perceived direction from its position at that moment using its perceived direction of motion. If subjects were to continue to extrapolate in the perceived direction of target motion from the position at which they perceive the target at each instant, the error would decrease during the movements. By analysing the differences between subjects' arm movements towards targets moving in different (apparent) directions with a linear second-order model, we show that the reduction in the error that this predicts is not enough to explain how subjects compensate for their initial misjudgments.

Simultaneous colour constancy revisited: an analysis of viewing strategies

We examined whether matching instructions influenced the eye movements that subjects made during a colour constancy experiment. The instructions changed the average duration of exposure to the spectrally biased surround. We also measured the influence that small changes in exposure duration have on the perceived colour. Eye movement and adaptation data were combined to predict differences in colour matches. Two of the five subjects showed an instructional effect that was much larger than that predicted. Analysis of the eye movements, and an experiment with dynamic surrounding colours, reveal that several viewing strategies do not account for the influence of the instruction.

Moving one's finger to a visually specified position: target orientation influences the finger's path

It has previously been shown that, when subjects are instructed to move their finger slowly from one point to another the finger follows a path that deviates systematically from a straight line connecting the two points. The deviation depends on the angle between this fictive line and a line connecting the subject's finger with his body. In the present study, we examined whether the deviation also depends on the target's orientation. In two experiments, subjects were instructed to move a finger slowly towards five targets. We recorded the finger's movements. In one experiment, the targets were aligned. In the other, they were oriented radially around the starting point. Otherwise, conditions were the same. The difference in target orientation influenced the finger's path. Most importantly, when the targets were oriented radially around the starting point, the finger's path was straight. We conclude that pointing is more than moving the finger to a specified position.

Perception and action are based on the same visual information: distinction between position and velocity

Ss were presented with spiders running from left to right at various velocities over a structured background. Motion of the background influenced the perceived velocity of the spider: Motion of the background in the opposite direction than the spider increased the perceived velocity. The perceived position of the spider was not influenced by background motion. Ss were asked to hit the spiders as quickly as possible. Fast spiders were hit with a higher velocity than slow spiders. The same effect was found if the spiders only differed in apparent velocity, induced by motion of the background. The trajectory of the hit was not influenced by motion of the background. The authors concluded that although velocity is nothing but the change of position in time, velocity and position are processed independently. Furthermore, these two separately processed sources of information are used in both perception and action.

Perception and action are based on the same visual information: distinction between position and velocity

Ss were presented with spiders running from left to right at various velocities over a structured background. Motion of the background influenced the perceived velocity of the spider: Motion of the background in the opposite direction than the spider increased the perceived velocity. The perceived position of the spider was not influenced by background motion. Ss were asked to hit the spiders as quickly as possible. Fast spiders were hit with a higher velocity than slow spiders. The same effect was found if the spiders only differed in apparent velocity, induced by motion of the background. The trajectory of the hit was not influenced by motion of the background. The authors concluded that although velocity is nothing but the change of position in time, velocity and position are processed independently. Furthermore, these two separately processed sources of information are used in both perception and action.

[An innovative program for public health training at the University of Geneva. Program during employment centered on the student and oriented to the population's health needs]

Switzerland's first Master degree course in public health was launched in the autumn of 1990 at the Geneva University School of Medicine. It is a 3 year, part-time course, which is learner-centred and community-oriented. The aim of the course is to prepare students to use a multi-disciplinary approach to plan, implement and evaluate activities intended to solve public health problems. Throughout the course, studies plan, implement and evaluate projects concerning health problems they have encountered in their work as health professionals. The curriculum includes individual and group work, discussions and seminars with teachers and students, and brainstorming sessions with specially trained facilitators. The students can thus identify and fulfil individual educational objectives while working on community-related health projects. Priority health needs of individuals and communities are thus the pivotal points of the novel approach to public health training.

Why two eyes are better than one for judgements of heading

Are two eyes needed for judging direction of self-motion? Traditional analyses stress that the pattern of optic flow in one eye is sufficient. The main difficulty is how to deal with the eye or head rotation. Extraretinal signals help, but humans can also discount the effect of rotation purely on the basis of monocular flow provided the scene contains depth. Depth differences give rise to changing binocular disparities when the observer moves. These disparities are ignored in monocular theories of judgements of heading. Using computer generated displays, we investigated whether stereoscopic presentation improves heading judgements for conditions that pose problems to the monocular observer. We found that adding disparities to simulated ego-motion through a cloud of dots made heading judgements up to four times more tolerant to motion noise. The same improvement was found when the disparities specify the initial distances throughout the motion sequence. We conclude that binocular disparities improve judgements of heading by imposing a depth order on the elements of the scene, not because they provide additional information on the elements' motion in depth.

Humans combine the optic flow with static depth cues for robust perception of heading

The retinal flow during normal locomotion contains components due to rotation and translation of the observer. The translatory part of the flow-pattern is informative of heading, because it radiates outward from the direction of heading. However, it is not directly accessible from the retinal flow. Nevertheless, humans can perceive their direction of heading from the compound retinal flow without need for extra-retinal signals that indicate the rotation. Two classes of models have been proposed to explain the visual decomposition of the retinal flow into its constituent parts. One type relies on local operations to remove the rotational part of the flow field. The other type explicitly determines the direction and magnitude of the rotation from the global retinal flow, for subsequent removal. According to the former model, nearby points are most reliable for estimating one's heading. In the latter type of model the quality of the heading estimate depends on the accuracy with which the ego-rotation is determined and is therefore most reliable when based on the most distant points. We report that subjects underestimate the eccentricity of heading, relative to the fixated point in the ground plane, when the visible range of the ground plane is reduced. Moreover we find that in perception of heading, humans can tolerate more noise than the optimal observer (in the least squares sense) would do if only using optic flow. The latter finding argues against both schemes because ultimately both classes of model are limited in their noise tolerance to that of the optimal observer, which uses all information available in the optic flow. Apparently humans use more information than is present in the optic flow. Both aspects of human performance are consistent with the use of static depth information in addition to the optic flow to select the most distant points. Processing of the flow of these selected points provides the most reliable estimate of the ego-rotation. Subsequent estimates of the heading direction, obtained from the translatory component of the flow, are robust with respect to noise. In such a scheme heading estimates are subject to systematic errors, similar to those reported, if the most distant points are not much further away than the fixation point, because the ego-rotation is underestimated.

Detecting changes in one's own velocity from the optic flow

Experiments were designed to establish whether we can use the optic flow to detect changes in our own velocity. Subjects were presented with simulations of forward motion across a flat surface. They were asked to respond as quickly as possible to a step increase in simulated ego-velocity. The smallest change for which subjects could respond within 500 ms was determined. At realistic simulated speeds of locomotion, the simulated ego-velocity had to increase by about 50%. The threshold for detecting changes in simulated ego-velocity was hardly better than the threshold for detecting other changes in the acceleration of the dots on the screen. It made little difference whether the surface across which the subject appeared to move was built up of dots, lines, or triangles; neither did it matter whether subjects saw the same image with both eyes, or whether the simulation was presented in stereoscopic depth. The results show that we are very poor at detecting changes in our own velocity on the basis of visual input alone.

Judging object velocity during smooth pursuit eye movements

Our tendency to constantly shift our gaze and to pursue moving objects with our eyes introduces obvious problems for judging objects' velocities. The present study examines how we deal with these problems. Specifically, we examined when information on rotations (such as eye movements) is obtained from retinal, and when from extra-retinal sources. Subjects were presented with a target moving across a textured background. Moving the background allowed us to manipulate the retinal information on rotation independently of the extra-retinal information. The subjects were instructed to pursue the target with their eyes. At some time during the presentation the target's velocity could change. We determined how various factors influence a subject's perception of such changes in velocity. Under more or less natural conditions, there was no change in perceived target velocity as long as the relative motion between target and background was maintained. However, experiments using conditions that are less likely to occur outside the laboratory reveal how extra-retinal signals are involved in velocity judgements.

The difference between the perception of absolute and relative motion: a reaction time study

We used a reaction-time paradigm to examine the extent to which motion detection depends on relative motion. In the absence of relative motion, the responses could be described by a simple model based on the detection of a fixed change in position. If relative motion was present, the responses could be modelled using characteristics of motion detectors. Comparing reaction times when relative and absolute velocity are equal with ones when relative velocity is twice the absolute velocity reveals that these detectors measure relative motion.

Judging an object's velocity when its distance changes due to ego-motion

This paper examines how one accounts for ones own movements when judging the velocity of a moving object, with emphasis on ego-motion perpendicular to the direction in which the object is moving. The "object" was a square that was tracked with smooth pursuit eye movements as it moved horizontally across a computer screen. Half-way through the presentation, the image on the screen changed in a manner simulating ego-motion in depth. At the same time, the speed with which the square moved across the screen also changed. Subjects were asked to report whether the target moved faster, at the same speed, or more slowly after the simulated ego-motion. The change in target velocity that was required for it to appear to continue to move at the same speed was determined for simulations containing different aspects of the information that is normally at our disposal. The results show that the change in the size of the image of the target, the expansion or contraction of the image of the surrounding, and differences in target motion between the two eyes (giving rise to vergence eye movements), all contribute to rendering the perceived object velocity independent of ego-motion.

[The lateral articular surface of the medial cuneiform bone facing the intermediate cuneiform bone]

300 medial cuneiform bones were examined to explore the different forms of the joint surface on the lateral side of the bone facing the intermediate cuneiform bone. This joint surface consists of two parts, a proximal one and a dorsal one. The proximal part is orientated dorsoplantarally. At its proximal margin there exists a tight contact with the proximal joint surface for the navicular bone. The dorsal part is sited at the dorsal margin of the lateral side of the bone. Different forms of fusion of these part could be seen. In 62.67% they show tight confluence. In 17.67% the fusion is limited to a slight contact. In the rest, 19.67%, there exists no contact between these two parts. These forms correlate to the proximal height of the bone. A large proximal height extends the degree of separation of the dorsal joint surfaces (consisting of the dorsal section of the proximal part and the whole dorsal of the joint surface for the intermediate cuneiform bone as well as the joint surface for the second metatarsal bone). Therefore these joint surfaces are split to their components.

Development of visually guided behaviour requires oriented contours

Kittens do not learn to use visual information to guide their behaviour if they are deprived of the optic flow that accompanies their own movements. We show that the optic flow that is required for developing visually guided behaviour is derived from changes in contour orientations, rather than from velocity patterns. We used several tests to assess visually guided behaviour. The performance of kittens that had only been allowed to see isolated dots of light was indistinguishable from that of kittens that had received no visual exposure at all. Kittens that had seen streaks of light performed better on several tasks. We discuss this finding with relation to the visual pathways that are presumably involved.

Epidemiological basis for clinical diagnosis of childhood malaria in endemic zone in West Africa

It is difficult to distinguish childhood malaria from other common febrile disorders by parasite count alone, because of the wide variation in tolerance of parasitaemia among individuals. We postulated that the proportion of febrile episodes among young children that can be attributed to parasitaemia varies according to simple clinical criteria. We studied 1114 children aged 2-9 years, who attended a dispensary in the Republic of Niger, with a case-control approach; each of 557 febrile children was matched with a non-febrile control by sex, age, ethnic group, and day of presentation. Febrile episodes were classified according to three clinical criteria: the presence of a likely non-malarial cause; the duration (less than 3 or more than 3 days before presentation); and the intensity (below 39 degrees C or 39 degrees C and above). There was no evidence for an association between febrile episodes and parasite count during the dry, low-transmission, season. During the rainy, high-transmission, season, by contrast, there was a highly significant relation (p less than 0.0001) between the likelihood of fever and the parasite count; each clinical criterion strengthened the association. There was no association between parasitaemia and low intensity fevers, with an obvious cause, that started 3 or more days before presentation, even in the rainy season; however, the relative risk of a fever that met all three criteria developing in those with vs those without parasitaemia was 27.5. The proportion of febrile cases attributable to detectable parasitaemia (population attributable risk) ranged from 0 to 0.92. Our results suggest that simple clinical criteria may be valuable in the selection of febrile patients for antimalarial treatment. In this geographic area, high fever of short duration and with no other obvious cause that occurs during the rainy season is most likely to be malaria.

Judging object motion during smooth pursuit eye movements: the role of optic flow

We tend to following moving objects with our eyes. To estimate their velocities, therefore, we must take account of our eye movements. During smooth pursuit, velocity judgements can be led astray by moving the background. Do we misjudge an object's velocity when the background moves because the additional shift of the background's image on the retina is interpreted as the result of additional motion of the observer rather than as motion of the background? In the present experiment, the traditional configuration of target and background was supplemented with a "floor of tiles" drawn in perspective directly under the "background". The motion of this new simulated plane was used to specify whether the additional retinal shift represents actual motion in the background, rotation of the observer's eyes, or observer locomotion parallel to the target. Moving the background clearly influenced the perceived velocity of the target. However, "specifying" whether the observer or the background had moved did not affect the outcome. For observer locomotion parallel to the target, the change in target velocity that is predicted by the optic flow depends on the perceived distance of the target. Nevertheless, presenting the target at different distances (by presenting different images of the two eyes) did not affect the subjects' settings. The results show that our judgement of objects' velocities does not depend on an assessment of our own movements on the basis of a global analysis of the optic flow.

Striking absence of long-lasting effects of early color deprivation on monkey vision

A monkey (Macaca fascicularis) spent its first three months under far red illumination that made color vision impossible. It developed normal spectral sensitivity. In the present study we examined two aspects of color vision that presumably reflect cortical connectivity. In the first part of this article we show that chromatic induction was also unaffected: a blue surrounding made a gray target appear to be yellow to the monkey. At five months of age, the deprived monkey did not readily use color to recognize objects, although it was able to do so if necessary. In the second part of this article we show that, as an adult, the monkey was quite willing to use color to categorize objects. We conclude that early color deprivation does not result in long lasting deficits in color vision.

Centrifugal motion bias in the cat's lateral suprasylvian visual cortex is independent of early flow field exposure

1. Neurones in the postero-medial part of the cat's lateral suprasylvian visual cortex (area PMLS) show an overall preference for centrifugal motion, suggesting that the PMLS may be specialized in the analysis of expanding optic flow fields associated with forward locomotion. 2. We examined whether the visual experience young kittens normally receive during forward locomotion guides the development of the centrifugal preference in the PMLS. 3. Seven kittens were reared in the dark and exposed to either expanding or contracting flow fields for at least 100 h during their 4th-11th weeks of life. Specific experience was achieved by exposing kittens either to flow field patterns generated on a screen or by actually moving them forward or backward in a carousel. 4. Our results show that although the development of directional selectivity in the PMLS requires visual experience, the centrifugal bias is independent of specific visual exposure. The preference for centrifugal motion among PMLS cells was just as evident in kittens exposed to contracting as in kittens exposed to expanding flow fields. 5. We conclude that the preference for centrifugal motion in the PMLS is not the result of anisotropic stimulation kittens receive during locomotion in early ontogeny, but is probably innately determined as a phylogenetic adaptation.

Hypohaptoglobinaemia as an epidemiological and clinical indicator for malaria. Results of two studies in a hyperendemic region in West Africa

Hypohaptoglobinaemia is a common phenomenon in tropical countries, where it is probably due to malaria-induced haemolysis. Two studies were carried out in a hyperendemic zone of West Africa to test its specificity and usefulness as an epidemiological indicator for measuring malaria endemicity. The first study evaluated the prevalence of hypohaptoglobinaemia before and after courses of antimalarial chemotherapy of varying duration. The second monitored haptoglobin levels in an untreated population during a whole year to compare its seasonal variations with those of several classic indicators of malaria. These studies suggest that in regions where malaria is endemic the prevalence of hypohaptoglobinaemia could be as useful an indicator as the parasitic index but would be much easier to establish and to monitor.

Event related potentials recorded from rats performing a reaction-time task

We recorded evoked potentials during performance of a reaction-time task, in which rats had to release a lever quickly in response to either a visual or an auditory stimulus for a food reward. We found two distinct peaks in their cortical evoked potentials. The first peak appeared at a fixed time after the stimulus, irrespective of the time it took the rat to release the lever. Its amplitude decreased with increasing reaction time. The second peak's latency was always longer when the rat took more time to release the lever, but its amplitude did not change. We believe that the first peak's amplitude is determined by the rat's "attention" to the stimulus, whereas the second peak's latency is related to the rat's "intention" to release the lever.

Effect of noradrenergic denervation on task-related visual evoked potentials in rats

The present study examines whether destruction of the noradrenergic innervation of the forebrain interferes with the processing of sensory information in a manner that results in impaired selective attention. Electro-cortical responses to task-relevant and irrelevant stimuli were found to be sensitive indicators of the rat's attention to the stimuli. The amplitude of the response to the task-relevant stimulus increased as the rat's performance improved. The response to irrelevant flashes of light depended on the predictability of the flashes and on the rat's level of arousal. Noradrenergic denervation (with the selective neurotoxin DSP4) did not affect either the behavioural response to a visual stimulus which the rat had been trained to respond to for a food reward, or the late positive potential evoked by this stimulus. Neither did it affect the response to continuous (temporally predictable) flashes of light that were irrelevant to the task. Although the response to unpredictable flashes was also largely unaffected, we did find an additional late component in this response after DSP4 treatment. These results show that the noradrenergic innervation of the occipital cortex does not always regulate the extent to which visual stimuli are processed, but that noradrenergic neurotransmission may be activated in order to diminish excessive processing of unexpected stimuli.

No increase in reaction-time after lesion of the dorsal noradrenergic bundle

In this study we examined whether lesions of rats' dorsal noradrenergic bundles affect their reaction times to temporally unpredictable stimuli. Injection of 6-hydroxydopamine into rats' dorsal bundles drastically reduced the noradrenaline content of their cerebral cortex. Nevertheless, 6OHDA treated rats could still react as quickly as controls. Moreover, the treatment did not affect the efficiency with which rats performed the task, even when they were forced to respond very quickly.

Central noradrenaline depletion during development and its effect on behaviour

Although early depletion of noradrenaline is known to affect the morphological development of various structures in the brain, it is not clear what implications this has for adult behaviour. In the present study, 6-hydroxydopamine (6OHDA) was injected into the lateral ventricles of 12 day old rats, permanently destroying most of the noradrenergic innervation of the spinal cord and of all the brain areas examined except for the pons/medulla, and reducing the dopamine content of the cerebral cortex considerably. The noradrenaline content of the heart, as well as general developmental parameters such as food intake and body weight, were unaffected. Despite the extensive noradrenaline depletion during development, these rats' spatial memory--as determined in a radial maze task--was no worse than that of controls. In a lever-pressing task the 6OHDA treated rats made no more errors than did controls, but performed more slowly. The results indicate that at least some aspects of learning, memory and sensory-motor ability can develop normally when the noradrenergic innervation of the brain is largely destroyed.

Visual and auditory evoked potentials in different areas of rat cerebral cortex

Visual and auditory evoked potentials were studied in the occipital, temporal, prefrontal and cingulate areas of the rat cerebral cortex. We found that both prefrontal and cingulate areas can respond to more than one sensory modality. The latencies of the response to light and sound, though slightly longer in these associative areas than in the two primary cortical regions, were still within the range of early sensory evoked responses (i.e. less than 50 ms).

6-Hydroxydopamine treatment does not affect the young rat's ability to modify its response when changing from food to water deprivation

In this study we examined whether depletion of forebrain noradrenaline would affect latent learning as predicted on the basis of the role attributed to the dorsal noradrenergic bundle in attention. Either 6-hydroxydopamine (6-OHDA) or saline was injected into the lateral ventricles of male Wistar pups on postnatal day 12. Immediately after weaning the rats were food deprived and trained to choose the left arm of a Y-maze which contained food while the right arm provided access to water. Once they had learnt to enter the left arm they were allowed access to food but not to water for one day and then tested again. All the rats quickly adjusted their behavioural response to the fact that they were deprived of water. The 6-OHDA-treated rats' behaviour did not differ significantly from that of the controls.

Neurochemical and electrophysiological disturbances mediate developmental behavioral alterations produced by medicines

Many centrally acting drugs which are prescribed for hypertension, depression, epilepsy, insomnia and asthma may also affect fetal brain neurotransmission and behavioral states. Nearly all these drugs enter the fetal circulation following maternal administration. The immaturity of the blood-brain barrier and greater accumulation in the developing brain make the fetal brain a major target of its mother's medication. Adverse effects that are seen in the fetus are not necessarily evident in its mother. We have shown that drugs like clonidine (an antihypertensive) and clomipramine (an antidepressant), which act on noradrenaline and serotonin neurotransmission in the brain, suppress rapid eye movement sleep in the developing rat. In adulthood, the neonatally treated rats showed hyperactivity, hyperanxiety, reduced sexual behavior, disturbed sleep patterns and reduced cerebral cortical size. Furthermore, such treatment induced an increase in voluntary alcohol consumption and a decreased adaptability of responses to changes in water deprivation in a Y-maze. Little is known about long-lasting consequences of centrally acting drugs used during late gestation in humans. Minor neurological disturbances, such as delayed visual motor performance, smaller head circumference, increased anxiety and disturbed sleep-wake patterns, have been reported in children born to hypertensive mothers treated with clonidine or alpha-methyl-dopa.

Growth and plasticity of rat cerebral cortex after central noradrenaline depletion

Male Wistar rats (aged 31 to 33 days) received bilateral intraventricular injections of saline or 6-hydroxydopamine and were subjected to either "standard" or "enriched" rearing conditions for 42 days. The treatment reduced cerebral cortical noradrenaline by 80% and decreased the growth of the cerebral cortex. It did not, however, prevent experience in an enriched environment from enhancing the growth of the cerebral cortex.

Early colour deprivation in a monkey (Macaca fascicularis)

Various forms of selective visual deprivation are known to affect the development of the monkey visual system. In the present study a monkey was born and spent the first three months of its life under red illumination. Despite this colour deprivation, the young monkey learnt to distinguish between colours. Furthermore, the monkeys' increment threshold spectral sensitivity was not affected by the deprivation.

Effects of cooling in infant rats on growth, maturation, sleep patterns and responses to food deprivation

The confounding effects of undernourishment and body cooling, resulting from maternal separation, were investigated by separating food and warmth deprivation. Rat pups aged 3-16 d were deprived of food for alternate 24-h periods by removal from the lactating mother. Some of the pups were placed with a foster mother, who kept them warm, whereas others were put in an empty cage at 22 degrees which resulted in a sharp drop in body temperature. Pups which were kept warm showed great fluctuations in weight between periods of starvation and feeding. The cooled pups lost less weight during deprivation but also recovered less on refeeding. The resultant growth rate was much lower in non-fostered (i.e. cooled) than in fostered pups. Up to the age of 8 d, cooled pups failed to raise their body temperature above that of the surroundings and did not digest the milk in their stomachs. Although, thereafter, they were able to raise their temperature to 26 degrees and to digest stomach contents, the extra energy expended resulted in more severe growth restriction. One-third of the pups died at 16 d but the rest were quickly rehabilitated by ad lib. feeding and showed a normal growth rate, although they remained smaller than the controls. The development of nipples, hair, eye opening and vaginal opening was related more to chronological age than to weight. A side effect of cooling was an almost complete abolition of active (REM) sleep, which is normally very high in infants; a slight rebound increase in active sleep was seen at 21 d. Direct as well as side effects of cooling may thus be responsible for some of the observed consequences of maternal separation.

An epidemiologic model for diabetes mellitus: incidence, prevalence, and mortality

An epidemiologic model is developed to describe the incidence, prevalence, and mortality of diabetes. Available data are reviewed, analyzed, and applied to the model. The model provides a framework for understanding diabetes on a population basis, and is useful in identifying needs and facilitating health care planning.

Impaired growth of the cerebral cortex of rats treated neonatally with 6-hydroxydopamine under different environmental conditions

Male Wistar rat pups received subcutaneous injections of either 100 mg/kg 6-hydroxydopamine (6-OHDA) or saline on days 1, 3, 5 and 7. The noradrenaline (NA) content of the cerebral cortex was reduced by 70% while sleep registration during the first two weeks of life did not show any significant differences between drug- and saline-treated animals. After weaning (day 25), both 6-OHDA- and saline-injected animals were reared under standard and enriched environmental conditions. Whereas a clear increase in cerebral cortical weight after experience with an enriched environment was found in saline-treated rats, 6-OHDA-treated animals had lower cortical weights and showed less increase due to the environment. These results demonstrate that catecholamine neurotransmission during early development influences the development and plasticity of the cerebral cortex.

Early colour deprivation in the pigeon

When cats and monkeys are deprived of specific stimuli during an early sensitive period the development of their visual system is known to be affected. In pigeons, pattern discrimination learning has been shown to be affected by monocular deprivation [2]. Our study was set up to examine whether colour discrimination learning could be affected by colour deprivation. Young pigeons were reared under restricted colour illumination for at least 3 months after hatching so as to obtain a group bred under red illumination, one bred under blue illumination and a control group. After this period several psychophysical tests were used to test the pigeons' sense of colour. No significant difference was found between the 'deprived' birds and the controls. The spectral sensitivity, determined with the help of the ERG, did not differ for the three groups. We conclude that early colour deprivation does not affect visual development in the pigeon.

Influence of growth medium, age in vitro and spontaneous bioelectric activity on the distribution of sensory ganglion-evoked activity in spinal cord explants

The role of serum added to the culture medium and of spontaneous bioelectric activity in the development of sensory afferent connections was studied, employing fetal mouse spinal cord explants with attached dorsal root ganglia (DRG) as an in vitro model system. Afferent DRG terminals in the cord explants were localized on the basis of 'fixed-latency' DRG-evoked action potentials, which were anatomically verified in several experiments using horseradish peroxidase histology. In serum-supplemented medium (HSSM), but not in chemically defined medium (CDM), those DRG fibers which grew into the dorsal side of the cord terminated predominantly within the dorsal cord region, and remained there throughout the experimental period (18-33 days in vitro). In contrast, ventrally entering fibers terminated equally in both the dorsal and the ventral cord regions in young cultures (18-24 days in vitro) but were no longer observed after 27 days in vitro. Cultures grown in HSSM with the addition of xylocaine, in order to chronically suppress spontaneous bioelectric activity, essentially corresponded (at 25-32 days in vitro) to the picture seen in the control series at the same age. On the basis of polysynaptic DRG-evoked responses in the cord, developmental changes in local neuronal networks were inferred which resulted in less spread of DRG-evoked activity with age in HSSM, and more spread with age in CDM-grown cultures. It is concluded that for the formation of selective DRG connections in the spinal cord: (i) a serum-borne factor plays a role: and (ii) functional activity is not required.

Chemically defined medium enhances bioelectric activity in mouse spinal cord-dorsal root ganglion cultures

Co-cultures of mouse spinal cord with dorsal root ganglion (DRG) cultures were grown either in horse serum (HS)-supplemented medium or in a serum-free, chemically defined medium (CDM). The cytoarchitecture of cord--DRG explants was fully retained in CDM, with little or no distortion due to flattening of the explant, as is invariably observed in HS-supplemented cultures. Functional properties such as bioelectric activity and DRG--spinal cord interconnectivity were well sustained in CDM.