Human neurobiology最新文献

{"title":"Lateral differences in visual processing: relative vs exclusive hemispheric specialization.","authors":"R Bruyer","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>In some cases, lateral differences reveal cerebral hemispheric asymmetry in cognitive operations. Such asymmetry can indicate the absolute dominance of one hemisphere, the \"dominant\" hemisphere managing the task whatever the hemisphere of entry. Consequently, a commissural transfer is needed for stimuli sent to the non-dominance as only relative: the hemisphere receiving the stimulus is able to manage it, but the dominant one can do it more accurately and/or faster than the other. These two models should be able to be distinguished by means of a correlational study and a study of the stimulated hemifield X responding hand interaction. The latter is based on the assumption of contralateral control of slight distal movements. These two methods were applied to data derived from 24 right-handed normals who were given three tasks for which right visual field superiority was expected: word/non-word discrimination, vowel/consonant classification of letters, and odd/even categorization of numbers. The stimuli were displayed centrally or laterally for 150 ms. The data indicated that the right-field superiority for words resulted from a relative dominance, that the right-field advantage for numbers resulted from an absolute dominance, and that no asymmetry emerged for letters.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"5 2","pages":"83-6"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14852323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear configuration and neuronal types of the nucleus niger in the brain of the human adult.","authors":"H Braak,&nbsp;E Braak","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The pigmentoarchitectonic analysis of the human nucleus niger reveals three main territories: Pars compacta, pars diffusa and pars reticulata. Seven subnuclei are recognized within the pars compacta. The nerve cell types forming the nucleus niger were investigated using a Golgi de-impregnation technique in combination with counterstaining of intraneuronally deposited pigment granules. Three principal types of neurons were defined: Type I was a medium-sized to large neuron, mainly encountered in the pars compacta, giving off a few thick and sparsely branching dendrites. These cells were richly endowed with elongated patches of Nissl material that were mainly found in the peripheral portions of the dendrites. One pole of the cell body contained tightly packed neuromelanin granules. Type II neurons were mainly found in the pars reticulata. They were variable in size and shape and generated, similar to type I neurons, extended and sparsely branching dendrites. Type II neurons were devoid of neuromelanin. A considerable number of these cells were lacking in lipofuscin deposits as well. Type III neurons occurred in all portions of the nuclear complex. The small cell body gave rise to a few thin and spineless dendrites. The axon and filiform processes of the dendrites showed small varicosities irregularly spaced apart. The pale cytoplasm contained small and intensely stained lipofuscin granules, which did not tend to agglomerate. Intraneuronally deposited neuromelanin and lipofuscin pigment can be considered a natural marker of the neuronal type in the nucleus niger of the human adult. The technique and the data provide a basis for investigations of the aged and the diseased human brain.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"5 2","pages":"71-82"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"13574729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of visual and static vestibular influences on dynamic posture control.","authors":"H C Diener,&nbsp;J Dichgans,&nbsp;B Guschlbauer,&nbsp;M Bacher","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Postural stabilization in altered visual and vestibular conditions was investigated in humans subjected to fast transient disturbances and during sinusoidal movement of the standing support. Visual inputs were varied by applying stroboscopic illumination, stabilizing the visual surround in respect to head movements, inducing apparent body movement in pitch by continuously moving stripe patterns up or down and by eye closure. Static vestibular input was modified by bending the head forwards or backwards, or to the right or left shoulder (eyes closed). Neither biomechanical parameters of standing nor EMG responses of the anterior tibial and triceps surae muscles were modified by the different visual and vestibular conditions during fast transient (80 degrees/s) platform movements 4 degrees toe-up. Continuous regulation of upright stance during sinusoidal movements (1 Hz, 0.3 Hz), however, clearly depended on the different modifications of visual and vestibular inputs. Fast transient disturbances are easily compensated in a reflex-like manner independent of visual and vestibular feedback. Continuous regulation of upright posture during slow disturbances, however, clearly depends on the evaluation of afferent information from the visual, vestibular, and proprioceptive systems.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"5 2","pages":"105-13"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14612571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulation of the Hoffmann reflex by rapid muscle contraction or release.","authors":"M Schieppati,&nbsp;A Nardone,&nbsp;M Musazzi","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The inhibition of the H-reflex of the Soleus (Sol) muscle that takes place during and after voluntary release of Sol muscle has been attributed to presynaptic inhibition of autogenetic spindle afferences. In the present study, the time-relationship between onset of H-reflex depression and termination of Sol contraction was investigated to ascertain whether the reflex inhibition is linked to the command to release, or whether it is an accompanying phenomenon connected to changes in the neural outflow from the periphery. A parallel investigation was carried out on the temporal characteristics of the facilitation of the H-reflex that precedes onset of Sol contraction, in an attempt to point at the different functional organization of the two motor tasks. Voluntary releases from a bilateral isometric plantar torque, or bilateral plantar flexions, were performed in response to an acoustic stimulus, in a reaction time (RT) situation. The intervals from the starting signal to complete termination, or to beginning, of the Sol EMG were measured. The H-reflex was evoked at random during the tasks in one leg and its amplitude was referred in time to the end, or to the onset, of the EMG recorded from the contralateral Sol muscle. The RTs of the termination of Sol EMG had an average duration of about 100 ms, being some 20 ms shorter than those of the onset of EMG. In the release-task, the H-reflex amplitude was higher than that of the controls during the holding phase, and started to decrease about 20 ms before the cessation of the EMG.(ABSTRACT TRUNCATED AT 250 WORDS)</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"5 1","pages":"59-66"},"PeriodicalIF":0.0,"publicationDate":"1986-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"14819854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hidden-face recognition: comparing foveal and extrafoveal performance.","authors":"M Hübner,&nbsp;I Rentschler,&nbsp;W Encke","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Ambiguous stimulus material was computer-generated by superimposing image components of a target-face and either a random checkerboard texture or a masking face. The recognition of the target-face was studied both for foveal and extrafoveal vision. Compensation of the peripheral disadvantage in image discrimination by rescaling the stimulus size was possible only in the case of texture. Comparable results were obtained from combining band-pass image components of the portraits. Results suggest that it is the relative inability to recover a signal from spatially correlated noise that characterizes visual discrimination in the peripheral visual field.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15110097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facial expressions of emotion in mother-infant interaction.","authors":"C Trevarthen","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Face movements of infants 2 months of age when they are interacting with their mothers give evidence both for innate representation of the mother as a partner in communication and for an emotional system that evaluates her expressions and regulates their interpersonal contact. Although the facial neuro-motor system is immature in infancy, it can generate many expressions that compare closely with those by which adults transmit emotions and control engagements and relationships. It also expresses rudiments of special motivation for speaking. Even newborns show clear evidence of organized facial expressions defining distinct communicative states that respond to maternal care. Emotional communication is multimodal; as infants gain in perceptuo-motor and cognitive powers, they both express and respond to simultaneous signals of affect in multiple channels of voice, gesture and postural change. Face expressions form but part of a stream of motor evidence of central affective state and its changes. Mothers present to infants a form of expressive activity (baby talk) that has clearly marked synchronous visible and audible features. The precocious expressive capacities and sensitivities of infants and maternal fostering of them would appear to be a human adaptation to facilitate development of observational learning and language. Developments in the first year expand the scope of communication and play without changing the fundamental emotional code by which infant and familiar caretakers construct and defend their special relationships.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 1","pages":"21-32"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15111342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Napping behavior during \"spontaneous internal desynchronization\": sleep remains in synchrony with body temperature.","authors":"J Zulley,&nbsp;S S Campbell","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Patterns of sleep and wakefulness exhibited in an environment without time cues are generally considered to be monophasic, with a distinct relationship between sleep episodes and the minimum of body core temperature. In some cases this relationship between major sleep episodes and temperature becomes replaced by an apparently varying phase relationship between the two variables called \"spontaneous internal desynchronization\". In the present study the sleep-wake and temperature data of six subjects living in an environment without time cues and exhibiting internal desynchronization were reanalyzed to include subjectively designated naps. Two groups of naps were identified based on their phase positions relative to temperature, with one group occurring around the temperature minimum and another group clustering approximately halfway between successive minima. The results support the suggestion that neither monophasic sleep placement nor sleep patterns typically associated with spontaneous internal desynchronization reflect biological sleep tendency. Rather, sleep tendency is reflected more accurately by the bimodal sleep patterns exhibited by subjects who are allowed to time their sleep and waking with no restrictions.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 2","pages":"123-6"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15143370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human contrast sensitivity: regional retinal differences.","authors":"W Skrandies","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Contrast sensitivity functions of foveal and of perifoveal upper and lower hemiretinal regions were measured in a population of twenty subjects. Foveal stimuli yielded consistently higher contrast sensitivities as well as a shift of the maximal sensitivity towards higher spatial frequencies as compared to perifoveal stimuli. The upper hemiretinal area was more sensitive at all spatial frequencies tested than the corresponding lower hemiretinal area. The statistical comparisons were highly significant, indicating not only regional retinal differences in visual acuity as reflected by the different contrast threshold levels at the highest spatial frequency, but also global differences between the upper and lower hemiretina systems not restricted to certain spatial frequency channels.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 2","pages":"97-9"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15143376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cortical organization of voluntary behavior in man.","authors":"P E Roland","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The research on regional changes in metabolism and blood flow in the human cerebral cortex during physiological activations is reviewed, with special reference to the significance of these changes for the organization of voluntary behavior. The only difference between cortical metabolic increases associated with voluntary behavior and cortical metabolic increases not associated with voluntary behavior was the activation of the primary motor cortex. Prior to the execution of any specific brain work, the brain tuned and prepared the cortical fields that were expected to participate in the task. This was reflected in metabolic increases in multiple cortical fields of a few cm2 which were then recruited for the task. Execution of the task increased the metabolism in those same cortical fields. The activated cortical fields constituted the largest functional elements of the cortex. If voluntary behavior was required, fields in the motor areas were recruited; otherwise, the organization of voluntary behavior did not differ from other brain work. In contrast to other cortical areas studied, the activation of the superior prefrontal cortex was independent on task-specific algorithms, sensory input and motor output. Its anterior division was always activated in tasks that were carried out according to a prior instruction; the mid-division was activated when the brain fixed attention or switched it between different cortical fields; the posterior division was activated when the paradigm contained sequential contingencies. The three sections of the superior prefrontal cortex participated in the organization of brain work by participating in the recruitment and attention control of cortical fields.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 3","pages":"155-67"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15177977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"\"Memory of the future\": an essay on the temporal organization of conscious awareness.","authors":"D H Ingvar","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The classical tripartite concept of time divided into past/present/future components, has been applied to the analysis of the functional cerebral substrate of conscious awareness. Attempts have been made to localize and to separate the neuronal machineries which are responsible for the experience of a past, a present, and a future. One's experience of a past is obviously related to one's memories. Memory mechanisms (in the conventional sense) have a well known functional relation to superficial and deep parts of the temporal lobe. Some such mechanisms presumably have a more widespread distribution. The experience of a present or a \"Now-situation\" is mediated by the sensory input. This input also exerts a role for conscious awareness of an inner Now-situation, independent of current afferent impulses, as shown by numerous observations on sensory deprivation. The main discussion is devoted to the experience of a future. Evidence is summarized that the frontal/prefrontal cortex handles the temporal organization of behaviour and cognition, and that the same structures house the action programs or plans for future behaviour and cognition. As these programs can be retained and recalled, they might be termed \"memories of the future\". It is suggested that they form the basis for anticipation and expectation as well as for the short and long-term planning of a goal-directed behavioural and cognitive repertoire. This repertoire for future use is based upon experiences of past events and the awareness of a Now-situation, and it is continuously rehearsed and optimized. Lesions or dysfunctions of the frontal/prefrontal cortex give rise to states characterized by a \"loss of future\", with consequent indifference, inactivity, lack of ambition, and inability to foresee the consequences of one's future behaviour. It is concluded that the prefrontal cortex is responsible for the temporal organization of behaviour and cognition due to its seemingly specific capacity to handle serial information and to extract causal relations from such information. Possibly the serial action programs which are stored in the prefrontal cortex are also used by the brain as templates for extracting meaningful (serial) information from the enormous, mainly non-serial, random, sensory noise to which the brain is constantly exposed. Without a \"memory of the future\" such an extraction cannot take place.</p>","PeriodicalId":77724,"journal":{"name":"Human neurobiology","volume":"4 3","pages":"127-36"},"PeriodicalIF":0.0,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15021472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}