Motor expertise modulates the unconscious processing of human body postures

Little is known about the cognitive background of unconscious visuomotor control of complex sports movements. Therefore, we investigated the extent to which novices and skilled high-jump athletes are able to identify visually presented body postures of the high jump unconsciously. We also asked whether or not the manner of processing differs (qualitatively or quantitatively) between these groups as a function of their motor expertise. A priming experiment with not consciously perceivable stimuli was designed to determine whether subliminal priming of movement phases (same vs. different movement phases) or temporal order (i.e. natural vs. reversed movement order) affects target processing. Participants had to decide which phase of the high jump (approach vs. flight phase) a target photograph was taken from. We found a main effect of temporal order for skilled athletes, that is, faster reaction times for prime-target pairs that reflected the natural movement order as opposed to the reversed movement order. This result indicates that temporal-order information pertaining to the domain of expertise plays a critical role in athletes’ perceptual capacities. For novices, data analyses revealed an interaction between temporal order and movement phases. That is, only the reversed movement order of flight-approach pictures increased processing time. Taken together, the results suggest that the structure of cognitive movement representation modulates unconscious processing of movement pictures and points to a functional role of motor representations in visual perception.     

On the origin of scatter in results of human bone strenght tests

Some of the more recent studies into the compressive and tensile strengths of small human bone samples are discussed. The scatter of results is compared to that for tests on cement which, like bone, is a composite material. A list of factors which may influence the result of strength tests on bone is given and discussed. It is suggested that by careful consideration of these factors and by standardization of the variables among them, the scatter of results could be reduced.     

On the origin of planar covariation of elevation angles during human locomotion

Leg segment rotations in human walking covary, so that the three-dimensional trajectory of temporal changes in the elevation angles lies close to a plane. Recently the role of central versus biomechanical constraints on the kinematics control of human locomotion has been questioned. Here we show, based on both modeling and experimental data, that the planar law of intersegmental coordination is not a simple consequence of biomechanics. First, the full limb behavior in various locomotion modes (walking on inclined surface, staircase stepping, air-stepping, crouched walking, hopping) can be expressed as 2 degrees of freedom planar motion even though the orientation of the plane and pairwise segment angle correlations may differ substantially. Second, planar covariation is not an inevitable outcome of any locomotor movement. It can be systematically violated in some conditions (e.g., when stooping and grasping an object on the floor during walking or in toddlers at the onset of independent walking) or transferred into a simple linear relationship in others (e.g., during stepping in place). Finally, all three major limb segments contribute importantly to planar covariation and its characteristics resulting in a certain endpoint trajectory defined by the limb axis length and orientation. Recent advances in the neural control of movement support the hypothesis about central representation of kinematics components.     

Contextual fear conditioning is disrupted by lesions of the subcortical, but not entorhinal, connections to the hippocampus

Recent studies have questioned the importance of the entorhinal cortex (ERC) for normal hippocampal function. For example, fibre-sparing ERC lesions have been found to have no effect on spatial learning in the watermaze. There is also doubt as to the importance of the ERC for contextual fear conditioning, with previous studies having yielded conflicting results. In an attempt to resolve this issue, the present study compared aspiration and cytotoxic ERC lesioned rats, along with fimbria-fornix (FFX) lesioned animals and sham operated controls, on an unsignalled contextual fear conditioning paradigm. The results of the present study show that whereas lesions of the FFX disrupted contextual freezing, neither aspiration nor cytotoxic ERC lesions had any effect on this behaviour. Aspiration ERC lesioned rats, however, like FFX lesioned animals, did display hyperactivity prior to the delivery of footshock. These results suggest that whereas projections between the hippocampus and subcortical structures are important for normal levels of contextual freezing, projections from the entorhinal cortex are not essential.     

On the origin of cancer

In this paper, I present a highly unorthodox and provocative hypothesis, namely that cancer is an evolutionarily derived phenomenon, dormant in every human cell and actively triggered in certain individuals. Cancer is shown to help maintain the integrity of the common gene pool through active elimination of individuals, thus serving a definite advantage for the survival of the species. Those individuals who are less capable of maintaining the integrity of their genome are stopped from inheriting defective genes, and even more important, from bequeathing defective deoxyribonucleic acid conservation traits to their offspring.Genome stability is a primary prerequisite for survival. The spread of deteriorated, imperfect genes should have a disastrous effect on a species' chances for survival. Although we tend to focus our attention on mutations as evolution's driving force, the stability of the deoxyribonucleic acid molecule is what really maintains life on our planet. When observing evolution's end product, we tend to forget that the extreme stability of the genetic material is a genetic quality by itself, a product of a long evolutionary process. The hypothesis presented here is that the selection pressure imposed by cancer is one of the mechanisms leading to this stability.     

3-D computer model of subcortical structures of human brain

Three-dimensional computer model of thalamus and adjacent formations of human brain has been elaborated on the basis of sagittal slices from the Schaltenbrand-Bailey stereotactic atlas. The model includes 120 morphologically distinguishable structures and consists of more than 16 million points (volume elements) each of them being associated with the particular structure in the brain. The model is stored in the long-term computer memory. A special software has been developed to facilitate utilizing the model obtained. The software facilitates synthesizing arbitrary cross-sections through the brain and provides the correspondence between the stereotactic coordinates of any point and its position on the screen of monitor. The coordinates of the point in the system of stereotactic atlas and the name of the structure, the point belongs to, are also supplied. It is also possible to get magnified images of cross-sections and to get isometrical images. The system enables the neurosurgeon to improve the planning and execution of stereotactic operations, and will also be helpful for education.     

On the origin of the soleus H-reflex modulation pattern during human walking and its task-dependent differences

Recently, Brooke and colleagues have suggested "that the strong inhibition arising from passive movement about the knee and hip joints, lays down the base for the soleus H-reflex gain modulation seen during human gait." In particular stretch-evoked afferent activity from the quadriceps muscle was emphasized as the most important source of movement-induced inhibition of the H-reflex. To test this hypothesis we examined the kinematics and electromyographic (EMG) activity of the leg during human walking and correlated these with the modulation pattern of the soleus H-reflex. To further test the possible contribution of stretch-evoked quadriceps afferent activity to the soleus H-reflex modulation pattern during walking different walking gaits were studied. In one condition subjects were asked to walk with their knee locked in full extension by a rigid knee brace. In a second condition subjects were asked to walk backwards. During normal walking, the soleus H-reflex modulation pattern is strongly correlated with the EMG events of the soleus and tibialis anterior (TA), but not with hip, knee, or ankle angular displacement or velocity. When subjects walked with the knee locked in full extension, the amplitude of the H-reflex, its modulation pattern, and the task-dependent changes of its amplitude were the same as during normal walking. During backward walking, the H-reflex increases in late swing before activity of the soleus has begun and while the knee is flexing, an observation that highlights central control of the H-reflex amplitude. The effects of imposed flexion of the knee in passive subjects were also reexamined. The knee flexion imposed by the experimenter followed the same trajectory as that which occurred during the swing phase of the subject's step cycle. It was found that imposed knee flexions elicited a burst of TA EMG activity with an average latency of 81.6 ms (SD = 21 ms) in six out of eight subjects. Inhibition of the H-reflex, when it occurred, was associated with the occurrence of this burst. When subjects voluntarily flexed their right knee from an initial quiet standing posture, the inhibition of the soleus H-reflex began before flexion of the knee or that of any other leg segment. Once again the onset of inhibition was closely associated with the onset of activity in the TA. In the discussion section the present observations are examined in light of the predictions made by the movement-induced inhibition hypothesis of Brooke et al. It will be concluded that none of the predictions of this hypothesis were corroborated by present tests done during human walking. In consequence, we suggest that the modulation pattern of the H-reflex observed during normal human walking is centrally determined, as are the task-dependent differences of its amplitude (e.g., standing versus the stance phase of human walking).     

The origin of human triploids

the data using a maximum-likelihood method was that 66.4 yo of the triploids were the result of dispermy, 23.6 % the result of fertilization of a haploid ovum by a diploid sperm formed by failure of the first meiotic division in the male and 10 % the result of a diploid egg formed by failure of the first maternal meiotic division. The possible sources of error inherent in the technique me reviewed and our results compared with previously published data. This work was supported by a grant from the Spencer Foundation, by grant no. 6–47 from the National Foundation and by grant no. HD 07879 from the National Institutes of Health. We are extremely grateful to Miss Shirley Yee of the Population Genetics Laboratory, University of Hawaii, for providing the maximum- likelihood estimates, and we thank Dr Kobara and the staff of the Pathology Department, the nursing staff of Kapiolani Hospital and Dr Julia Tsuei of the Department of Obstetrics and Gynecology without whose help in collecting the specimens the present study would have been impossible.     

On the origin and significance of neuromelanin

The amount of cytoplasm within catecholamine neurons occupied by neuromelanin was found to increase progressively with the patient's age. The accretion of neuromelanin was accompanied by an expansion of the cytoplasm of neurons in the substantia nigra and locus ceruleus. These observations support the concept that neuromelanin is a waste product of catecholamine metabolism, derived from the oxidation of dopamine, nonrepinephrine, and related compounds to quinones. The existence of oxidative pathways for catecholamines suggests that defects in their compartmentalization, transport, or degradation may present the cell with sufficient levels of cytotoxic quinones and free radical species to result in the degeneration of neurons observed in Parkinson's disease.     

On the origin of avian air sacs

For many vertebrates the lung is the largest and lightest organ in the body cavity and for these reasons can greatly affect an organism's shape, density, and its distribution of mass; characters that are important to locomotion. In this paper non-respiratory functions of the lung are considered along with data on the respiratory capacities and gas exchange abilities of birds and crocodilians to infer the evolutionary history of the respiratory systems of dinosaurs, including birds. From a quadrupedal ancestry theropod dinosaurs evolved a bipedal posture. Bipedalism is an impressive balancing act, especially for tall animals with massive heads. During this transition selection for good balance and agility may have helped shape pulmonary morphology. Respiratory adaptations arising for bipedalism are suggested to include a reduction in costal ventilation and the use of cuirassal ventilation with a caudad expansion of the lung into the dorsal abdominal cavity. The evolution of volant animals from bipeds required yet again a major reorganization in body form. With this transition avian air sacs may have been favored because they enhanced balance and agility in flight. Finally, I propose that these hypotheses can be tested by examining the importance of the air sacs to balance and agility in extant animals and that these data will enhance our understanding of the evolution of the respiratory system in archosaurs.     

On the nature and origin of 'nigate'

This study examined the nature and origin of 'sense of nigate,' which is an awkward and uncomfortable feeling one has toward specific, relatively few others, especially in a interpersonal situation. Study 1 investigated its nature with a questionnaire administered to company employees (200 men and 45 women) and undergraduates (243 men and 205 women). Two factors were found for the sense: troublesomeness and apprehension. It should be noted that apprehension was lower for management than non-management workers. This tendency was due to the worker position, rather than his/her age. In Study 2, self-monitoring scale (Lennox & Wolfe, 1984) was administered to 60 high school students (12 men, 47 women, and one unknown), to investigate the origin of the sense. As predicted, sense of nigate had a negative correlation with the ability to modify self-presentation, and positive one with the sensitivity to expressive behavior in others.