Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SPACE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1987

The lumbar subdural extraarachnoid space of humans: an anatomical study using spinaloscopy in autopsy cases.

The lumbar subdural extraarachnoid space was examined by spinaloscopy in 15 autopsy subjects. Special attention was paid to the ease with which the space opened up and also to the extent of view achieved. In ten cases the space opened up with ease, in four cases with difficulty, and in one case it was not possible to establish the subdural space at all. The bevel of an 18-gauge Tuohy needle introduced into the subdural space could be visualized in eight of 13 cases. An epidural catheter was then passed through the Tuohy needle into the subdural space in eight cases and was visualized in six of them. Although care must be exercised in drawing conclusions for clinical epidural anesthesia from autopsy cases, this study confirms the possibility of placing both the bevel of a Tuohy needle and an epidural catheter in the subdural space. The results reemphasize the need for caution suggested by other reports regarding the possibility of subdural puncture in epidural anesthesia and subsequent injection of anesthetic solution into the subdural space.

Aged↗
PubMed1993

Communication between space crews and ground personnel: a survey of astronauts and cosmonauts.

A total of 54 astronauts and cosmonauts returned questionnaires which addressed several aspects of communication between space crews and ground personnel. Two factors were rated as significantly helping this communication: Shared Experience and Excitement of Space Flight. Two additional factors were judged to significantly hinder space-ground communication: Spacecraft Ambient Noise and Space Sickness. Respondents also significantly endorsed the value of contact with loved ones on Earth as having a positive influence on mission performance, particularly cosmonauts and long-duration space travelers. The need for a private space-ground transmission link was mentioned by several respondents. There was no consensus as to whether or not negative personal information should be withheld until the space crew returned to Earth, although some respondents indicated that this might be justified during short-duration as opposed to long-duration missions. These findings have important scientific and operational implications for future manned space missions.

Aerospace Medicine↗
PubMedDate not supplied

Visual object localization through vestibular and neck inputs. 1: Localization with respect to space and relative to the head and trunk mid-sagittal planes.

Object localization in space signals in the absence of an external reference (visual, auditory, haptic) involves a signal of the head in space (vestibular). The present study asks whether signals of body position relative to the support surface (proprioceptive) are involved as well, by investigating the role of vestibular-neck interaction (dissociating head and trunk position). Normal human subjects saw a light spot (object) and continuously nulled displacement steps of the spot. They did so before and after vestibular and/or neck rotational stimulation in the horizontal plane, reproducing a predesignated object localization in space (i), relative to the head mid-sagittal (ii), and relative to the trunk mid-sagittal (iii). The predominant frequency contained in the stimuli was varied (0.05, 0.1, and 0.4 Hz). (I) Object localization in space upon whole-body rotation (vestibular stimulus) at high frequency was veridical, whereas that at low frequency fell short. Almost identical results were obtained for trunk rotation about the stationary head (neck stimulus). In contrast, when combining the stimuli in the form of head rotation on the stationary trunk, the results were veridical, independent of stimulus frequency. Additional findings obtained with a large variety of vestibular-neck stimulus combinations suggest a linear summation of vestibular and neck signals. (II) Object localization with respect to the head was approximately veridical, being independent of vestibular and neck stimulation. However, this only applied if subjects were not biased by a head-in-space motion illusion of neck origin. (III) Object localization with respect to the trunk was veridical in all conditions tested. The findings support a recently developed concept, according to which humans evaluate the kinematic state of a visual object in space by (a) relating it to that of the body support by means of an essentially ideal proprioceptive coordinate transformation, and (b) relating, in turn, the kinematic state of the support to a vestibularly derived notion of space, using a proprioceptive coordinate transformation that "knows" the vestibular transfer characteristics. One important aspect is that object localization in space always is veridical during head and trunk rotation relative to a stationary support (for example, the ground) despite non-ideal vestibular transfer characteristics. Additional findings in patients with chronic loss of vestibular function confirm this concept.

Adult↗
PubMed1997

The perinephric space and renal fascia: review of normal anatomy, pathology, and pathways of disease spread.

The perinephric space is a cone-shaped retroperitoneal compartment containing the kidney, adrenal gland, perinephric fat, fibrous bridging septa, and a rich network of perirenal vessel and lymphatics. Perinephric space pathology may originate from within or outside the confines of the perirenal fascia. Most intrinsic perinephric space disease arises from the kidney or adrenal gland, and secondarily involves the perinephric space. Disease originating outside the cone of renal fascia may spread to the perinephric space via lymphatics (i.e., metastatic spread) or by directly transgressing perirenal fascial planes (e.g., invasive tumor or infections). Additionally, infiltrating soft tissue or rapidly accumulating retroperitoneal fluid may travel into or out of the perinephric space via perinephric bridging septa and renal fascia. In this article, we review the normal anatomy of the perinephric space and renal fascia, emphasizing the significance of retroperitoneal interfascial planes and perinephric bridging septa as a potential conduit for retroperitoneal disease spread. This review of normal anatomy and pathways of disease spread serves as background for a discussion of a variety of specific pathologic conditions that may involve the perinephric space and retroperitoneal fascia, including pancreatitis, retroperitoneal hematoma, urinoma, metastatic disease, and perirenal varices.

Diagnostic Imaging↗
PubMed1997

Guidelines on the use of space maintainers following premature loss of primary teeth.

OBJECTIVE: To formulate evidence-based guidelines on the appropriate use of space maintaining appliances to prevent or reduce the severity of malocclusion in the permanent dentition following the premature loss of primary teeth. OPTIONS: Placement of lingual arch, palatal arch, band-loop, crown-loop, and intra-alveolar space maintainers. OUTCOMES: Reduced prevalence or severity of space loss in the primary or mixed dentition, reduced prevalence or severity of malocclusion in the permanent dentition measured as significant changes in: crowding, ectopic eruption, impacted teeth, Angle's class II or III occlusion, crossbite, deep overbite, deep overjet, or midline shift. EVIDENCE: Articles published from 1966 to 1996, located though Medline searches. Only clinical trials, cohort studies, case-control studies, or large case series were considered. VALUES: Relevant clinical findings were evaluated and categorized using evidence-based methods and values established by the Canadian Task Force on the Periodic Health Examination. A recommendation was developed for the use of space maintainers. BENEFITS, HARMS AND COSTS: The potential benefits of using space maintaining appliances include reduced prevalence or severity of: crowding, ectopic eruption, tooth impaction, crossbite, excessive overbite and overjet, and poor molar relationship. Other advantages include the potential for considerable cost savings by reducing the need for future orthodontic treatment. The potential disadvantages of using space maintaining appliances include soft tissue impingement, interference with eruption of adjacent teeth, pain, plaque accumulation, caries, and broken, dislodged or lost appliances. RECOMMENDATIONS: There is poor evidence to recommend for or against the use of space maintainers to prevent or reduce the severity of malocclusion in the permanent dentition (see Table 1, Recommendation C) Decisions regarding the use of space maintainers must therefore be guided by factors other than scientific evidence.

Humans↗
PubMed1998

Posture, locomotion, spatial orientation, and motion sickness as a function of space flight.

This article summarizes a variety of newly published findings obtained by the Neuroscience Laboratory, Johnson Space Center, and attempts to place this work within a historical framework of previous results on posture, locomotion, motion sickness, and perceptual responses that have been observed in conjunction with space flight. In this context, we have taken the view that correct transduction and integration of signals from all sensory systems is essential to maintaining stable vision, postural and locomotor control, and eye-hand coordination as components of spatial orientation. The plasticity of the human central nervous system allows individuals to adapt to altered stimulus conditions encountered in a microgravity environment. However, until some level of adaptation is achieved, astronauts and cosmonauts often experience space motion sickness, disturbances in motion control and eye-hand coordination, unstable vision, and illusory motion of the self, the visual scene, or both. Many of the same types of disturbances encountered in space flight reappear immediately after crew members return to earth. The magnitude of these neurosensory, sensory-motor and perceptual disturbances, and the time needed to recover from them, tend to vary as a function of mission duration and the space travelers prior experience with the stimulus rearrangement of space flight. To adequately chart the development of neurosensory changes associated with space flight, we recommend development of enhanced eye movement systems and body position measurement. We also advocate the use of a human small radius centrifuge as both a research tool and as a means of providing on-orbit countermeasures that will lessen the impact of living for long periods of time with out exposure to altering gravito-inertial forces.

Humans↗
PubMed2001

Evolution of telemedicine in the space program and earth applications.

Remote monitoring of crew, spacecraft, and environmental health has always been an integral part of the National Aeronautics and Space Administration's (NASA's) operations. Crew safety and mission success face a number of challenges in outerspace, including physiological adaptations to microgravity, radiation exposure, extreme temperatures and vacuum, and psychosocial reactions to space flight. The NASA effort to monitor and maintain crew health, system performance, and environmental integrity in space flight is a sophisticated and coordinated program of telemedicine combining cutting-edge engineering with medical expertise. As missions have increased in complexity, NASA telemedicine capabilities have grown apace, underlying its role in the field. At the same time, the terrestrial validation of telemedicine technologies to bring healthcare to remote locations provides feedback, improvement, and enhancement of the space program. As NASA progresses in its space exploration program, astronauts will join missions lasting months, even years, that take them millions of miles from home. These long-duration missions necessitate further technological breakthroughs in tele-operations and autonomous technology. Earth-based monitoring will no longer be real-time, requiring telemedicine capabilities to advance with future explorers as they travel deeper into space. The International Space Station will serve as a testbed for the telemedicine technologies to enable future missions as well as improve the quality of healthcare delivery on Earth.

History, 20th Century↗
PubMed2005

Circadian rhythms, sleep, and performance in space.

Maintaining optimal alertness and neurobehavioral functioning during space operations is critical to enable the National Aeronautics and Space Administration's (NASA's) vision "to extend humanity's reach to the Moon, Mars and beyond" to become a reality. Field data have demonstrated that sleep times and performance of crewmembers can be compromised by extended duty days, irregular work schedules, high workload, and varying environmental factors. This paper documents evidence of significant sleep loss and disruption of circadian rhythms in astronauts and associated performance decrements during several space missions, which demonstrates the need to develop effective countermeasures. Both sleep and circadian disruptions have been identified in the Behavioral Health and Performance (BH&P) area and the Advanced Human Support Technology (AHST) area of NASA's Bioastronautics Critical Path Roadmap. Such disruptions could have serious consequences on the effectiveness, health, and safety of astronaut crews, thus reducing the safety margin and increasing the chances of an accident or incident. These decrements oftentimes can be difficult to detect and counter effectively in restrictive operational environments. NASA is focusing research on the development of optimal sleep/wake schedules and countermeasure timing and application to help mitigate the cumulative effects of sleep and circadian disruption and enhance operational performance. Investing research in humans is one of NASA's building blocks that will allow for both short- and long-duration space missions and help NASA in developing approaches to manage and overcome the human limitations of space travel. In addition to reviewing the current state of knowledge concerning sleep and circadian disruptions during space operations, this paper provides an overview of NASA's broad research goals. Also, NASA-funded research, designed to evaluate the relationships between sleep quality, circadian rhythm stability, and performance proficiency in both ground-based simulations and space mission studies, as described in the 2003 NASA Task Book, will be reviewed.

Adaptation, Physiological↗
PubMed2005

Interpersonal issues in space: Shuttle/Mir and beyond.

Anecdotal reports from space and results from space analogue experiments on Earth have suggested a number of interpersonal issues that may negatively affect crewmember performance and well-being. We examined some of these issues in a questionnaire survey of 54 astronauts and cosmonauts who had flown in space and in a 135-d Mir Space Station simulation study in Moscow. We also conducted a NASA-funded study involving missions to the Mir Space Station, where 5 U.S. astronauts, 8 Russian cosmonauts, and 42 U.S. and 16 Russian mission control subjects completed weekly mood and group climate questionnaires. There were few findings that supported hypothesized changes in tension and group behavior in terms of time on-orbit. Crewmembers reported decreasing leader support in the second half of their mission, and U.S. astronauts gave evidence for a novelty effect in the first few weeks. There was strong support for our hypothesized displacement of tension and negative emotions from crewmembers to mission control personnel and from mission control personnel to management. There were several significant differences in response between Americans vs. Russians and crewmembers vs. mission control personnel. These findings have training countermeasure implications for future on-orbit space missions. During expeditionary type space missions, such as a trip to Mars, additional interpersonal stressors will need to be dealt with. These include increased crew autonomy, more dependence on onboard technical resources, communication delays with the Earth, increased isolation and monotony, and the Earth-out-of-view phenomenon.

Aerospace Medicine↗
PubMed2005

Cultural factors and the International Space Station.

The American and Russian/Soviet space programs independently uncovered psychosocial risks inherent in long-duration space missions. Now that these two countries are working together on the International Space Station (ISS), American-Russian cultural differences pose an additional set of risk factors. These may echo cultural differences that have been observed in the general population of the two countries and in space analogue settings, but little is known about how relevant these are to the select population of space program personnel. The evidence for the existence of mission-relevant cultural differences is reviewed and includes cultural values, emotional expressivity, personal space norms, and personality characteristics. The review is focused primarily on Russia and the United States, but also includes other ISS partner countries. Cultural differences among space program personnel may have a wide range of effects. Moreover, culture-related strains may increase the probability of distress and impairment. Such factors could affect the individual and interpersonal functioning of both crewmembers and mission control personnel, whose performance is also critical for mission safety and success. Examples from the anecdotal and empirical literature are given to illustrate these points. The use of existing assessment strategies runs the risk of overlooking important early warning signs of behavioral health difficulties. By paying more attention to cultural differences and how they might be manifested, we are more likely to detect problems early while they are still mild and resolvable.

Astronauts↗
PubMed2006

Three-dimensional microcomputed tomography imaging of basic multicellular unit-related resorption spaces in human cortical bone.

This study employed microcomputed tomography (micro-CT) as a novel means for visualizing the morphology and quantifying the range (length) of basic multicellular unit (BMU)-related resorption spaces in human cortical bone. We tested the hypotheses that the density and range of spaces vary with age and sex. The sample included 82 human (18-92 years) anterior femoral midshaft samples. The morphology of the spaces (n = 99) was varied, including unidirectional, bidirectional, branched, and even highly clustered forms. The density of resorption spaces was negatively correlated with age for the combined sexes and females, with Spearman's rho values of -0.355 (P < 0.001) and -0.522 (P = 0.002), respectively. The density of spaces did not differ significantly between the sexes (P = 0.735). Mean range +/- SD for the combined sexes, females, and males was 2,706 +/- 1,177, 2,681 +/- 1,247, and 2,718 +/- 1,150 microm, respectively. Numerical simulation of the effect of the 7,000 microm scan field of view suggested that the actual mean range of the spaces for the pooled sample was actually on the order of 3,770 microm. Range did not correlate significantly with age for the combined sexes (P = 0.587) or females (P = 0.345) and males (P = 0.896) considered separately and was not significantly different (P = 0.883) between the sexes. These results suggest that the range of BMUs is not affected by age. The age-dependent decrease in resorption space density for the females and pooled sexes was most likely a consequence of cortical rarefaction, leading to difficulty detecting resorption spaces with micro-CT, rather than a decrease in overall remodeling activity.

Adolescent↗
PubMed2004

Determination of the width of the presacral space on magnetic resonance imaging.

Presacral space enlargement may be the first sign of certain diseases. The normal width of the presacral space has not been widely investigated and in all previous studies was calculated from lateral radiographs obtained at barium enema examination. Our study determined the normal width of the presacral space on MRI and investigated a possible difference between men and women. The width of the presacral space was measured retrospectively from sagittal T2-weighted MR images of 193 patients (87 males; 106 females, aged 18-83 years). Presacral space width was measured separately for S1, S2, and S3 vertebral levels from the anterior surface of the vertebral bodies to the closest part of the posterior wall of the rectum. Differences between male and female subjects were analyzed by t-tests. Normal mean widths of the presacral space in men and women were 16.2 mm and 11.9 mm for S1, 14.9 mm and 11.2 mm for S2, and 13.0 mm and 10.6 mm for S3, respectively. Measurements of the presacral space width in men were significantly larger than in women at all three levels (P < 0.001 for S1, P < 0.001 for S2, P = 0.006 for S3). In summary, the presacral space width measured on MRI was found to be significantly larger in the male than in the female population.

Adolescent↗
PubMed1995

Causes of increasing width of right anterior extrarenal space seen in ultrasonographic examinations.

The right anterior extrarenal space is composed of the perirenal fascia, the right anterior perirenal space, the right anterior pararenal space, and the liver capsule. To clarify the probable causes of an increasing width of the right anterior extrarenal space, the width was measured using ultrasonography for a period of 8 months. The right anterior extrarenal space was measured 3 cm from the superior renal pole and the smallest width obtained in several different scan planes was used. In 1,114 ultrasound examinations, 35 patients were found to have an increased width of the right anterior extrarenal space. Among the 35 cases, the common probable causes for such a condition were found in 27 cases. Eight patients had hyperchogenicity in the right pararenal space, a condition considered to be due to an acute inflammation, including acute pancreatitis, acute cecal diverticulitis, acute appendicitis, ischemic bowel, acute cholangitis, liver abscess, and penetrated duodenal ulcer. Chronic inflammations of an adjacent organ, a previous history of laparotomy, a malignancy with peritoneal metastases, and treatment with corticosteroid were considered the causes behind the condition in the 19 patients with normal echogenicity. For the remaining 8 patients, causes were not found during the follow-up period. This study indicates that life-threatening diseases, such as acute or chronic inflammatory diseases and malignancy of the abdomen, could be the cause of an increase in the width of this space.

Abdomen↗
PubMed1991

Human perception of horizontal trunk and head rotation in space during vestibular and neck stimulation.

The vestibular signal of head motion in space must be complemented by a neck signal of the trunk-to-head excursion in order to provide the individual with information on trunk motion in space. This consideration led us to study psychophysically the role of vestibular-neck interaction for human self-motion perception. Subjects (Ss) were presented with passive horizontal rotations of their trunk and/or head (sinusoidal rotations, f = 0.025 - 0.4 Hz) in the dark for vestibular and neck stimulation, as well as for combinations of both. Ss' perception was evaluated in terms of gain (veridical perception of stimulus magnitude, G = 1), phase, and detection threshold. (1) Perception of trunk rotation in space. During vestibular stimulation (whole-body rotation) and neck stimulation (trunk rotation with the head kept stationary) the frequency-transfer characteristics underlying this perception were very similar. The gain fell short; it was only about 0.7 at 0.4 and 0.2 Hz stimulus frequency and was further attenuated with decreasing frequency. In contrast, the phase was close to that of actual trunk position. The gain attenuation was found to be a function of the peak angular velocity of the stimulus, a fact, which we related to a 'velocity threshold' of the order of 1 deg/s. During the various vestibular-neck combinations used, Ss' perception was again erroneous, reflecting essentially the sum of its two non-ideal constituents. However, there was one noticeable exception; during the combination 'head rotation on stationary trunk', Ss veridically perceived their trunk as stationary (compatible with the notion that the sum yielded 'zero'). (2) Perception of head rotation in space. During vestibular stimulation, Ss' estimates showed the same non-ideal gain-vs.-frequency characteristics as described above for the trunk. Neck stimulation induced an illusion as if the head had been rotated in space. This neck contribution was such that, when it was combined with its vestibular counterpart during head rotation on stationary trunk, the perception became almost veridical. On closer inspection, however, this neck contribution was found to reflect the sum of two components; one was the non-ideal neck signal contributing to the perception of 'trunk in space', the other was an almost ideal neck signal of head-on-trunk rotation. (3) The results could be described by a simple model. In this model, the erroneous vestibular signal 'head in space' is primarily used to create an internal representation of 'trunk in space'.(ABSTRACT TRUNCATED AT 400 WORDS)

Head↗
PubMed1995

CT and MRI of the normal and diseased perivertebral space.

The perivertebral space is in the midline, in the deep tissues of the neck, and can be identified from the skull base above to the mediastinum below. It is a discrete space completely enclosed by the deep layer of deep cervical fascia. The fascial attachments of the perivertebral space divide it into two areas, the anterior prevertebral and posterior paraspinal portions. We made a retrospective analysis of the radiologic and clinical records of 52 patients with lesions in the perivertebral space, to identify the imaging features that mark a lesion as originating in the perivertebral space and define the spectrum of pathology which occurs in the space. Mass lesions present in the prevertebral or paraspinal portions. In the former they usually involve the vertebral body, displacing the prevertebral muscles anteriorly. Epidural extension from lesions in the perivertebral space proper is common. Masses in the paraspinal perivertebral space usually displace the paraspinal muscles away from the spine. We found 9 inflammatory lesions, 29 malignant and 6 benign tumors, and 8 miscellaneous lesions.

Adolescent↗
PubMed1989

Frequency and space representation in the primary auditory cortex of the frequency modulating bat Eptesicus fuscus.

1. Frequency and space representation in the auditory cortex of the big brown bat, Eptesicus fuscus, were studied by recording responses of 223 neurons to acoustic stimuli presented in the bat's frontal auditory space. 2. The majority of the auditory cortical neurons were recorded at a depth of less than 500 microns with a response latency between 8 and 20 ms. They generally discharged phasically and had nonmonotonic intensity-rate functions. The minimum threshold, (MT) of these neurons was between 8 and 82 dB sound pressure level (SPL). Half of the cortical neurons showed spontaneous activity. All 55 threshold curves are V-shaped and can be described as broad, intermediate, or narrow. 3. Auditory cortical neurons are tonotopically organized along the anteroposterior axis of the auditory cortex. High-frequency-sensitive neurons are located anteriorly and low-frequency-sensitive neurons posteriorly. An overwhelming majority of neurons were sensitive to a frequency range between 30 and 75 kHz. 4. When a sound was delivered from the response center of a neuron on the bat's frontal auditory space, the neuron had its lowest MT. When the stimulus amplitude was increased above the MT, the neuron responded to sound delivered within a defined spatial area. The response center was not always at the geometric center of the spatial response area. The latter also expanded with stimulus amplitude. High-frequency-sensitive neurons tended to have smaller spatial response areas than low-frequency-sensitive neurons. 5. Response centers of all 223 neurons were located between 0 degrees and 50 degrees in azimuth, 2 degrees up and 25 degrees down in elevation of the contralateral frontal auditory space. Response centers of auditory cortical neurons tended to move toward the midline and slightly downward with increasing best frequency. 6. Auditory space representation appears to be systematically arranged according to the tonotopic axis of the auditory cortex. Thus, the lateral space is represented posteriorly and the middle space anteriorly. Space representation, however, is less systematic in the vertical direction. 7. Auditory cortical neurons are columnarly organized. Thus, the BFs, MTs, threshold curves, azimuthal location of response centers, and auditory spatial response areas of neurons sequentially isolated from an orthogonal electrode penetration are similar.

Acoustic Stimulation↗
PubMed2003

Are object- and space-based attentional biases both important to free-viewing perceptual asymmetries?

In contrast to unilateral neglect patients, who overattend to the right hemispace, normal participants attend more to the left: a phenomenon known as pseudoneglect. Two experiments examined whether pseudoneglect results from object- or space-based attentional biases. Normal participants ( n=38, 22) made luminance judgments for two left/right mirror-reversed luminance gradients (greyscales task). The relative lateral position of the greyscales stimuli was manipulated so that object- and space-based coordinates were congruent or incongruent. A baseline condition was also included. A leftward bias, found for the baseline condition, was annulled in the incongruent condition, demonstrating an opposition of object- and space-based biases. The leftward bias was reduced in the congruent condition where object- and space-based biases were expected to be additive. This effect was attributed to extraneous factors, which were avoided in the second experiment by presenting the greyscales stimuli sequentially. Once again, no bias was observed in the incongruent condition where object- and space-based biases were opposed. The leftward bias in the congruent condition was the same as the baseline. The results can be explained by a combination of space- and object-based biases or by space-based biases alone and are discussed with reference to a variety of models, which describe the distribution of attention across space.

Adolescent↗
PubMed2001

Visual object localisation in space. Interaction of retinal, eye position, vestibular and neck proprioceptive information.

Perceptual updating of the location of visual targets in space after intervening eye, head or trunk movements requires an interaction between several afferent signals (visual, oculomotor efference copy, vestibular, proprioceptive). The nature of the interaction is still a matter of debate. To address this problem, we presented subjects (n=6) in the dark with a target (light spot) at various horizontal eccentricities (up to +/-20 degrees ) relative to the initially determined subjective straight-ahead direction (SSA). After a memory period of 12 s in complete darkness, the target reappeared at a random position and subjects were to reproduce its previous location in space using a remote control. For both the presentation and the reproduction of the target's location, subjects either kept their gaze in the SSA (retinal viewing condition) or fixated the eccentric target (visuo-oculomotor). Three experimental series were performed: A, "visual-only series": reproduction of the target's location in space was found to be close to ideal, independently of viewing condition; estimation curves (reproduced vs presented positions) showed intercepts approximately 0 degrees and slopes approximately 1; B, "visual-vestibular series": during the memory period, subjects were horizontally rotated to the right or left by 10 degrees or 18 degrees at 0.8-Hz or 0.1-Hz dominant frequency. Following the 0.8-Hz body rotation, reproduction was close to ideal, while at 0.1 Hz it was partially shifted along with the body, in line with the known vestibular high-pass characteristics. Additionally, eccentricity of target presentation reduced the slopes of the estimation curves (less than 1); C, "visual-vestibular-neck series": a shift toward the trunk also occurred after low-frequency neck stimulation (trunk rotated about stationary head). When vestibular and neck stimuli were combined (independent head and trunk rotations), their effects summed linearly, such that the errors cancelled each other during head rotation on the stationary trunk. Variability of responses was always lowest for targets presented at SSA, irrespective of intervening eye, head or trunk rotations. We conclude that: (1) subjects referenced "space" to pre-rotatory SSA and that the memory trace of the target's location in space was not altered during the memory period; and that (2) they used internal estimates of eye, head and trunk displacements with respect to space to match current target position with the memory trace during reproduction; these estimates would be obtained by inverting the physical coordinate transformations produced by these displacements. We present a model which is able to describe these operations and whose predictions closely parallel the experimental results. In this model the estimate of head rotation in space is not obtained directly from the vestibular head-in-space signal, but from a vestibular estimate of the kinematic state of the body support.

Adult↗