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Head Movements (head + movement)
Selected AbstractsOrganization of rat vibrissa motor cortex and adjacent areas according to cytoarchitectonics, microstimulation, and intracellular stimulation of identified cellsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2004Michael Brecht Abstract The relationship between motor maps and cytoarchitectonic subdivisions in rat frontal cortex is not well understood. We use cytoarchitectonic analysis of microstimulation sites and intracellular stimulation of identified cells to develop a cell-based partitioning scheme of rat vibrissa motor cortex and adjacent areas. The results suggest that rat primary motor cortex (M1) is composed of three cytoarchitectonic areas, the agranular medial field (AGm), the agranular lateral field (AGl), and the cingulate area 1 (Cg1), each of which represents movements of different body parts. Vibrissa motor cortex corresponds entirely and for the most part exclusively to AGm. In area AGl body/head movements can be evoked. In posterior area Cg1 periocular/eye movements and in anterior area Cg1 nose movements can be evoked. In all of these areas stimulation thresholds are very low, and together they form a complete representation of the rat's body surface. A strong myelinization and an expanded layer 5 characterize area AGm. We suggest that both the strong myelinization and the expanded layer 5 of area AGm may represent cytoarchitectonic specializations related to control of high-speed whisking behavior. J. Comp. Neurol. 479:360,373, 2004. © 2004 Wiley-Liss, Inc. [source] Azoospermia with Klippel-Feil anomalyINTERNATIONAL JOURNAL OF UROLOGY, Issue 2 2008Yukihiro Umemoto Abstract: We present a case of azoospermia with Klippel-Feil anomaly. Klippel-Feil anomaly is characterized by the fusion of two or more cervical vertebrae and a short neck, limitation of head movement, and low posterior hairline. The association of this anomaly with MURCS (Müllerian-duct asplasia, renal agenesis, and cervical somite dysplasia) is traditionally regarded as being limited to females, but it has been hypothesized that men displaying the combination of azoospermia, segmentation abnormalities of the cervicothoracic spine, and renal anomalies have a male analog of MURCS. Here we describe the first case of MURCS in a male in whom testicular sperm extraction was carried out. [source] Analysis of brain activity immediately before conscious teeth clenching using magnetoencephalographic methodJOURNAL OF ORAL REHABILITATION, Issue 7 2007T. IIDA summary, The reasons for unconscious teeth clenching have not been clarified. The long-term goal of our project was the elucidation of processing in the brain immediately before unconscious teeth clenching, in order to clarify its significance in humans. The objective of the present study was to establish a magnetoencephalographic (MEG) method of measuring brain activity immediately before clenching, and to clarify the time-course of brain activity immediately before conscious clenching. We measured the MEG signal in six subjects before, during and after clenching in a protocol that restricted head movement <5 mm. We derived tomographic estimates of brain activity for each time slice of data, as well as time courses for regional brain activations. Analysis of the tomographic images and time courses yielded statistical maps of activity in the motor, pre-motor and somatosensory cortices immediately before clenching in all subjects. Activations were found bilaterally, but with a strong unilateral bias in most subjects. Our results demonstrate that the MEG procedures, we have introduced are capable of measuring brain activity immediately before clenching, and indicate that analysis should begin from at least 200 ms before electromyogram onset. [source] Variation and context of yawns in captive chimpanzees (Pan troglodytes)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2010Sarah-Jane Vick Abstract Primate yawns are usually categorized according to context (e.g. as a threat, anxious, or rest yawn), but there has been little consideration of whether these yawns are best regarded as a unitary behavior that only differs with respect to the context in which it is observed. This study examined the context and precise morphology of yawns in a group of 11 captive chimpanzees. Focal video sampling was used to describe the morphology and intensity of 124 yawns using ChimpFACS, a system for coding facial movements. Two distinct forms of yawn were identified, a full yawn and a yawn which is modified by additional actions that reduce the mouth aperture. These modified yawns may indicate some degree of voluntary control over facial movement in chimpanzees and, consequently, multiple functions of yawning according to context. To assess context effects, mean activity levels (resting, locomotion, and grooming) and scratching rates were compared one minute before and after each yawn. Locomotion was significantly increased following both types of yawn, whereas scratching rates significantly increased following modified yawns but decreased following full yawns. In terms of individual differences, males did not yawn more than females, although male yawns were of higher intensity, both in the degree of mouth opening and in the amount of associated head movement. These data indicate that yawning is associated with a change in activity levels in chimpanzees, but only modified yawns may be related to increased arousal. Different types of yawn can therefore be differentiated at the morphological level as well as context level. Am. J. Primatol. 72:262,269, 2010. © 2009 Wiley-Liss, Inc. [source] Eye gaze in virtual environments: evaluating the need and initial work on implementationCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 11 2009Norman Murray Abstract For efficient collaboration between participants, eye gaze is seen as being critical for interaction. Video conferencing either does not attempt to support eye gaze (e.g. AcessGrid) or only approximates it in round table conditions (e.g. life size telepresence). Immersive collaborative virtual environments represent remote participants through avatars that follow their tracked movements. By additionally tracking people's eyes and representing their movement on their avatars, the line of gaze can be faithfully reproduced, as opposed to approximated. This paper presents the results of initial work that tested if the focus of gaze could be more accurately gauged if tracked eye movement was added to that of the head of an avatar observed in an immersive VE. An experiment was conducted to assess the difference between user's abilities to judge what objects an avatar is looking at with only head movements being displayed, while the eyes remained static, and with eye gaze and head movement information being displayed. The results from the experiment show that eye gaze is of vital importance to the subjects correctly identifying what a person is looking at in an immersive virtual environment. This is followed by a description of the work that is now being undertaken following the positive results from the experiment. We discuss the integration of an eye tracker more suitable for immersive mobile use and the software and techniques that were developed to integrate the user's real-world eye movements into calibrated eye gaze in an immersive virtual world. This is to be used in the creation of an immersive collaborative virtual environment supporting eye gaze and its ongoing experiments. Copyright © 2009 John Wiley & Sons, Ltd. [source] Predictive tracking over occlusions by 4-month-old infantsDEVELOPMENTAL SCIENCE, Issue 5 2007Claes Von Hofsten Two experiments investigated how 16,20-week-old infants visually tracked an object that oscillated on a horizontal trajectory with a centrally placed occluder. To determine the principles underlying infants' tendency to shift gaze to the exiting side before the object arrives, occluder width, oscillation frequency, and motion amplitude were manipulated resulting in occlusion durations between 0.20 and 1.66 s. Through these manipulations, we were able to distinguish between several possible modes of behavior underlying ,predictive' actions at occluders. Four such modes were tested. First, if passage-of-time determines when saccades are made, the tendency to shift gaze over the occluder is expected to be a function of time since disappearance. Second, if visual salience of the exiting occluder edge determines when saccades are made, occluder width would determine the pre-reappearance gaze shifts but not oscillation frequency, amplitude, or velocity. Third, if memory of the duration of the previous occlusion determines when the subjects shift gaze over the occluder, it is expected that the gaze will shift after the same latency at the next occlusion irrespective of whether occlusion duration is changed or not. Finally, if infants base their pre-reapperance gaze shifts on their ability to represent object motion (cognitive mode), it is expected that the latency of the gaze shifts over the occluder is scaled to occlusion duration. Eye and head movements as well as object motion were measured at 240 Hz. In 49% of the passages, the infants shifted gaze to the opposite side of the occluder before the object arrived there. The tendency to make such gaze shifts could not be explained by the passage of time since disappearance. Neither could it be fully explained in terms of visual information present during occlusion, i.e. occluder width. On the contrary, it was found that the latency of the pre-reappearance gaze shifts was determined by the time of object reappearance and that it was a function of all three factors manipulated. The results suggest that object velocity is represented during occlusion and that infants track the object behind the occluder in their ,mind's eye'. [source] REVIEW ARTICLE: Cortical control of eye and head movements: integration of movements and perceptsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2007L. Longtang Chen Abstract The cortical control of eye movements is well known. It remains unclear, however, as to how the eye fields of the frontal lobes generate and coordinate eye and head movements. Here, we review the recent advances in electrical stimulation studies and evaluate relevant models. As electrical stimulation is conducted in head-unrestrained, behaving subjects with the evoked eye and head movements sometimes being indistinguishable from natural gaze shifts, a pertinent question becomes whether these movements are evoked by motor programs or sensory percepts. Recent stimulation studies in the visual cortex and the eye fields of the frontal lobes have begun to bring both possibilities to light. In addition, cognitive variables often interact with behavioral states that can affect movements evoked by stimulation. Identifying and controlling these variables are critical to our understanding of experimental results based on electrically evoked movements. This understanding is needed before one can draw inferences from such results to elucidate the neural mechanisms underlying natural and complex movements. [source] Simultaneously recorded EEG,fMRI: Removal of gradient artifacts by subtraction of head movement related average artifact waveformsHUMAN BRAIN MAPPING, Issue 10 2009Limin Sun Abstract Electroencephalograms (EEGs) recorded simultaneously with functional magnetic resonance imaging (fMRI) are corrupted by large repetitive artifacts generated by the switched MR gradients. Several methods have been proposed to remove these distortions by subtraction of averaged artifact templates from the ongoing EEG. Here, we present a modification of this approach which accounts for head movements to improve the extracted template. Using the fMRI analysis package statistical parametric mapping (SPM; FIL London) the head displacement is determined at each half fMRI-volume. The basic idea is to apply a moving average algorithm for template extraction but to include only epochs that were obtained at the same head position as the artefact to be removed. This approach was derived from phantom EEG measurements demonstrating substantial variations of the artefact waveform in response to movements of the phantom in the MRI magnet. To further reduce the residual noise, we applied a resampling algorithm which aligns the EEG samples in a strict adaptive manner to the fMRI timing. Finally, we propose a new algorithm to suppress residual artifacts such as those occasionally observed in case of brief strong movements, which are not reflected by the movement indicator because of the limited temporal resolution of the fMRI sequence. On the basis of EEG recordings of six subjects these measures combined reduce the residual artefact activity quantified in terms of the spectral power at the gradient repetition rate and its harmonics by roughly 20 to 50% (depending on the amount of movement) predominantly in frequencies beyond 30 Hz. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source] Transformed Social Interaction, Augmented Gaze, and Social Influence in Immersive Virtual EnvironmentsHUMAN COMMUNICATION RESEARCH, Issue 4 2005Jeremy N. Bailenson Immersive collaborative virtual environments (CVEs) are simulations in which geographically separated individuals interact in a shared, three-dimensional, digital space using immersive virtual environment technology. Unlike videoconference technology, which transmits direct video streams, immersive CVEs accurately track movements of interactants and render them nearly simultaneously (i.e., in real time) onto avatars, three-dimensional digital representations of the interactants. Nonverbal behaviors of interactants can be rendered veridically or transformed strategically (i.e., rendered nonveridically). This research examined augmented gaze, a transformation in which a given interactant's actual head movements are transformed by an algorithm that renders his or her gaze directly at multiple interactants simultaneously, such that each of the others perceives that the transformed interactant is gazing only at him or her. In the current study, a presenter read a persuasive passage to two listeners under various transformed gaze conditions, including augmented gaze. Results showed that women agreed with a persuasive message more during augmented gaze than other gaze conditions. Men recalled more verbal information from the passage than women. Implications for theories of social interaction and computer-mediated communication are discussed. [source] Olfactory Familiarization and Discrimination in Preterm and Full-Term NewbornsINFANCY, Issue 1 2002Nathalie Goubet The purpose of this study was to observe olfactory detection and discrimination in preterm and full-term newborns. Infants were familiarized for 10 trials with either vanillin or anethole. On each trial, a cotton swab perfumed with one of the odors was slowly moved in front of the baby's nose for 10 sec. For half of the preterm and full-term infants, a new odor was presented after the last familiarization trial (experimental groups). For the other half, the same odor as during familiarization was presented (control groups). Facial and head movements for both populations and heart rates for preterm infants were recorded before, during, and after odor presentation. Preterm infants reacted to the scents by increasing facial actions and heart rate but not head movements. Full-term infants increased facial and head movements. Neither population showed a clear behavioral habituation pattern, but full-term newborns had a significantly reduced facial reactivity on the last familiarization trial compared to preterm infants. Preterm newborns did, however, show cardiac habituation on the last familiarization trial. Preterm and full-term infants presented with a new odor after familiarization increased responding compared to infants presented with the same odor, indicating their ability to discriminate between 2 odors. Infants' reactivity and discrimination to odors indicate preterm and full-term newborns' ability to be attuned to their olfactory environment. [source] Oro-facial activities in sleep bruxism patients and in normal subjects: a controlled polygraphic and audio,video studyJOURNAL OF ORAL REHABILITATION, Issue 2 2009K. M. C. DUTRA Summary, To our knowledge, the large spectrum of sleep motor activities (SMA) present in the head and neck region has not yet been systematically estimated in normal and sleep bruxism (SB) subjects. We hypothesized that in the absence of audio,video signal recordings, normal and SB subjects would present a high level of SMA that might confound the scoring specificity of SB. A retrospective analysis of several SMA, including oro-facial activities (OFA) and rhythmic masticatory muscle activities (RMMA), was made from polygraphic and audio,video recordings of 21 normal subjects and 25 SB patients. Sleep motor activities were scored, blind to subject status, from the second night of sleep recordings. Discrimination of OFA included the following types of activities: lip sucking, head movements, chewing-like movements, swallowing, head rubbing and scratching, eye opening and blinking. These were differentiated from RMMA and tooth grinding. The frequency of SMA per hour of sleep was lower in normal subjects in comparison with SB patients (P < 0·001). Up to 85% of all SMA in normal subjects were related to OFA while 30% of SMA in SB patients were related to OFA scoring (P < 0·001). The frequency of RMMA was seven times higher in SB patients than in normal subjects (P < 0·001). Several SMA can be observed in normal and SB subjects. In the absence of audio,video signal recordings, the discrimination of various types of OFA is difficult to achieve and may lead to erroneous estimation of SB-related activities. [source] Sexual dimorphism of body size and shell shape in European tortoisesJOURNAL OF ZOOLOGY, Issue 4 2003Ronald E. Willemsen Adult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca, T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni. Males grew to a larger size than females in T. marginata, and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata, vertical head bobs and carapace butting in T. graeca, and mounting and tail thrusting in T. hermanni. There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species. [source] Characterization of the Vestibulo-Ocular Reflex Evoked by High-Velocity MovementsTHE LARYNGOSCOPE, Issue 7 2004François D. Roy HBSc Abstract Objectives/Hypothesis: The horizontal angular vestibulo-ocular reflex (VOR) plays an important role in stabilizing images on the retina throughout head rotations. Current evidence suggests that the VOR behaves linearly at low velocities and nonlinearly at high velocities. The aim of the research was to evaluate and characterize the normal behavior of the reflex evoked by high-velocity head rotations. Study Design: Case control study. Methods: Manually applied head-thrust movements with peak velocities in the range of 100° to 500°/s and peak accelerations up to 7,000°/s 2 were performed on normal volunteers. These head thrusts were comparable with those described in detail by Halmagi and coworkers. Eye and head movements were recorded using the magnetic search coil method. Results: The gain of the VOR is linear at low velocities and saturates at head velocities greater than 350°/s. The values for the normal gain of the reflex were approximated by means of the area between two nonlinear functions. The directional difference parameter, exploring the symmetry of the reflex, indicated that the VOR in normal subjects is symmetric. Conclusion: The gain of the VOR in individuals with intact vestibular function is nonlinear at high angular head velocities. We propose a quantitative means using two nonlinear functions to characterize the normal range of values for the gain of the VOR in individuals with normal vestibular function. A directional difference parameter used in conjunction with the normal range of gains can detect small differences in the symmetry of the VOR and, consequently, reveal unilateral vestibular loss. [source] Abnormal vestibular responses to vertical head motion in cerebellar ataxiaANNALS OF NEUROLOGY, Issue 2 2008Ke Liao MS Falls pose an important problem to neurologists caring for patients with cerebellar disorders. Normal human gait is characterized by prominent up-and-down linear head movements (vertical translations). Thus, we asked whether patients with cerebellar gait ataxia showed abnormal responses of otolithic vestibuloocular reflexes to this motion. Compared with healthy subjects, all cerebellar patients showed impaired otolith-ocular responses. Neurologists often test the rotational vestibuloocular reflexes in cerebellar patients, but our results indicate that vestibular responses to vertical linear motion are severely affected. Impairment of the corresponding otolith-spinal reflexes may contribute substantially to falls. Ann Neurol 2008 [source] Visuospatial encoding deficits and compensatory strategies in schizophrenia revealed by eye movement analysis during a working memory taskACTA NEUROPSYCHIATRICA, Issue 2 2009Luca Cocchi Objective: To investigate scanpath abnormalities during the encoding of static stimuli in schizophrenia and their interaction with visuospatial working memory (VSWM) dysfunction. Methods: Outpatients with schizophrenia and control subjects were asked to encode a static pattern for subsequent recognition after a short delay. We measured the number of correct and incorrect choices. We also assessed the number and the distribution of fixations, the scanning time in specific regions of interest (ROIs) and the head movements during the encoding of the stimuli. The distributions of fixations and scanning time in definite ROIs during the discrimination of the correct pattern from the foils were also measured. Results: Patients recognised fewer correct patterns than controls. Correct trials in patients were characterised by a specific exploration of the central part of the stimulus during its presentation, whereas this feature was absent in incorrect trials. However, the scanning time and the numbers of fixations and head movements during encoding were similar in both groups and unrelated to recognition accuracy. In both groups, correct trials were associated with a selective exploration of the correct pattern amongst the six possibilities during recognition. Furthermore, patients gave more attention to incorrect patterns with a leftmost element identical to that of the correct response and also those approximating its global structure. Conclusion: Patients showed a VSWM deficit independent of oculomotor dysfunctions and head movements during encoding. Patients' correct trials were related to specific scanning during encoding and discrimination phases. Analysis of these patterns suggests that patients try to compensate for reduced VSWM ability by using specific encoding strategies. [source] Motor performance in very preterm infants before and after implementation of the newborn individualized developmental care and assessment programme in a neonatal intensive care unitACTA PAEDIATRICA, Issue 6 2009Anna Ullenhag Abstract Aim: To compare motor performance in supine position at the age of 4-months corrected age (CA) in very preterm (VPT) infants cared for in a neonatal intensive care unit (NICU) before and after the implementation of the Newborn Individualized Developmental Care and Assessment Program (NIDCAP). Methods: Assessments of motor performance in supine position according to level of motor development and quality of motor performance were made, using the Structured Observation of Motor Performance in Infants (SOMP-I). Subjects: VPT infants cared for in a NICU at a Swedish university hospital before, Group A (n = 68), and after, Group B (n = 58), the implementation of developmentally supportive care based on NIDCAP. Results: The infants who were treated after the introduction of NIDCAP showed higher level of motor development in the arms/hands and trunk. No significant group differences were noted in total deviation score for the respective limbs, but lower frequency of lateral flexion in head movements, extension,external rotation,abduction, extension,internal rotation,adduction and varus and valgus position in the feet was found in the NIDCAP group, compared with those treated before the introduction. Conclusion: The infants who were treated after NIDCAP care had been implemented showed a higher level of motor development in arms/hand and trunk and fewer deviations in head, legs and feet at 4-months CA than infants treated before NIDCAP implementation. The observed changes may be due to NIDCAP and/or improved perinatal and neonatal care during the studied time period. [source] | |||||||||||||