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PubMed2004

An "Oblique Effect" in infants' haptic perception of spatial orientations.

The present research addresses the question of the "oblique effect" (better discrimination of the vertical orientation than of an oblique orientation) in manual haptic perception of orientations (without visual control) by 5-month-old infants. A familiarization/reaction to novelty procedure was used. The results revealed the occurrence of a haptic oblique effect. These findings are similar to those obtained in infant visual perception. We suggest that 5-month-old infants predominately use vertical orientation as a reference norm to perceive haptically spatial orientations. We discuss the implications of these results for both orientation processing and anatomofunctional level contributing specifically to the haptic oblique effect.

Discrimination, Psychological↗
PubMed1992

Role of the cerebellum in spatial orientation in the rat.

Adult DA/HAN strain rats were submitted to a spatial orientation task consisting of finding a reward in an open field. They were first submitted to an initial learning session and 10 days later to a retrieval test. The animals were divided into four groups of five rats each: animals that were cerebellectomized before the initial learning session or after the initial learning session, sham-operated rats, and control (intact) animals. Different parameters that characterize the spatiotemporal organization of the rat's exploratory behavior were quantified. From the results, it can be concluded that the cerebellum is not absolutely necessary in the processes that sustain spatial learning but that it is involved in the mechanisms sustaining focused spatial memory and in the cognitive processes of the motor program elaboration and not only in the regulation of the movement being done.

Animals↗
PubMedDate not supplied

[Spatial orientation of human on a background of +Gz loads and head movements].

Spatial orientation of six normal subjects (19-28 y/o males) was investigated on a centrifuge with a radius of 6.55 m by the method of subjective haptic vertical during head movements on the pattern of working head movements of pilots impacted by +Gz loads. The investigation showed that the trend and intensity of G-excess illusion could be related to the occurrence of tangential components of the gyroscopic moment +Gz vector in the utricle otolith plane.

Adult↗
PubMed2001

[Neural basis of spatial orientation and memory of routes: topokinetic memory or topokinesthesic memory].

The neural basis of spatial orientation and the memory of routes have been explored by brain imaging (PET SCAN and fMRI) in human. Several cognitive strategies and several types of reference frames can be used by the brain to establish relations between our body and the environment. Four categories of brain areas have been considered: the areas involved in egocentric and allocentric coding on one hand and on the other hand the areas involved in the "route" like and the "survey or map" like strategies used during tasks in which subjects had to mentally remember a path by mental navigation or mental scanning of a map. The results have confirmed that parietal and frontal structures involved in "spatial neglect" are also found to be involved in the egocentric orientation tasks of subjective midline detection. More generally we have been able to identify parieto-frontal areas involved in visuo-spatial memory. In addition we have identified the areas involved in the cortical processing of vestibular information and lastly we have shown that in addition to the parieto-frontal areas a parieto temporal lobe network is involved in allocentric tasks and also during mental navigation by route or survey strategies. These results contribute to the identification of the neural basis of topographic memory but they also suggest that we have to define a particular type of spatial memory which is involved in the memory of routes and movements which we suggest to call "topo-kinetic" or "topo-kinesthetic" memory.

Brain Mapping↗
PubMed1989

An apparatus to retain the spatial orientation of breast biopsies.

An apparatus has been designed to retain the spatial orientation of breast biopsies throughout surgery, transport and processing in the pathology laboratory. It does not interfere with regular surgical procedures and simplifies the surgeon's task of marking the orientation of a specimen. As the use of the apparatus does not involve either chemical or physical substances it is an appropriate handling procedure for those specimens requiring sensitive testing procedures such as cell culture.

Biopsy↗
PubMed1989

Consideration of spatial orientation mechanisms as related to elderly fallers.

This study examines some aspects of spatial orientation mechanisms in idiopathic elderly fallers. Tests of visual perception of verticality and horizontality showed no significant difference between 6 fallers and 6 controls, although 50% of fallers indicated difficulties in the recognition of postural tilt. Results of responses to standing balance indicated that fallers leant more heavily on a supporting frame and were more spatially deflected when standing on one leg than were controls. The results suggest that fallers may rely on visual cues to recognise and correct postural deviations, thus implying that their proprioceptive feedback is impaired.

Accidental Falls↗
PubMed2003

Top-down control over biased competition during covert spatial orienting.

Larger benefits of spatial attention are observed when distractor interference is prevalent, supporting the view that spatial selection facilitates visual processing by suppressing distractor interference. The present work shows that cuing effects with identical visual displays can grow substantially as the probability of distractor interference increases. The probability of interference had no impact on spatial cuing effects in the absence of distractors, suggesting that the enlarged cuing effects were not caused by changes in signal enhancement or in the spatial distribution of attention. These findings suggest that attentional control settings determine more than where spatial attention is directed; top-down settings also influence how attention affects visual processing, with increased levels of distractor exclusion when distractor interference is likely.

Analysis of Variance↗
PubMed2004

Preparatory activity in visual cortex indexes distractor suppression during covert spatial orienting.

The deployment of spatial attention induces retinotopically specific increases in neural activity that occur even before a target stimulus is presented. Although this preparatory activity is thought to prime the attended regions, thereby improving perception and recognition, it is not yet clear whether this activity is a manifestation of signal enhancement at the attended locations or suppression of interference from distracting stimuli (or both). We investigated the functional role of these preparatory shifts by isolating a distractor suppression component of selection. Behavioral data have shown that manipulating the probability that visual distractors will appear modulates distractor suppression without concurrent changes in signal enhancement. In 2 experiments, functional magnetic resonance imaging revealed increased cue-evoked activity in retinotopically specific regions of visual cortex when increased distractor suppression was elicited by a high probability of distractors. This finding directly links cue-evoked preparatory activity in visual cortex with a distractor suppression component of visual selective attention.

Adult↗
PubMed2002

[History of vestibular-spatial orientation research].

In order to advance our scientific endeavors in the field of vestibular-spatial orientation research, it is important to know how much research has already been carried out, and how much accurate information we currently possess. It is mandatory to have sufficient background information in order to establish a solid working hypothesis utilizing insightful approaches. Accordingly, this historical survey covers various research endeavors from the beginning of aviation until the end of 2001, including Skylab, Microgravity Vestibular Investigations, and Neurolab.

Humans↗
PubMed2000

Modulation of spatial orientation processing by mental imagery instructions: a MEG study of representational momentum.

Under appropriate conditions, an observer's memory for the final position of an abruptly halted moving object is distorted in the direction of the represented motion. This phenomenon is called "representational momentum" (RM). We examined the effect of mental imagery instructions on the modulation of spatial orientation processing by testing for RM under conditions of picture versus body rotation perception and imagination. Behavioral data were gathered via classical reaction time and error measurements, whereas brain activity was recorded with the help of magnetoencephalography (MEG). Due to the so-called inverse problem and to signal complexity, results were described at the signal level rather than with the source location modeling. Brain magnetic field strength and spatial distribution, as well as latency of P200m evoked fields were used as neurocognitive markers. A task was devised where a subject examined a rotating sea horizon as seen from a virtual boat in order to extrapolate either the picture motion or the body motion relative to the picture while the latter disappeared temporarily until a test-view was displayed as a final orientation candidate. Results suggest that perceptual interpretation and extrapolation of visual motion in the roll plane capitalize on the fronto-parietal cortical networks involving working memory processes. Extrapolation of the rotational dynamics of sea horizon revealed a RM effect simulating the role of gravity in rotational equilibrium. Modulation of the P200m component reflected spatial orientation processing and a non-voluntary detection of an incongruity between displayed and expected final orientations given the implied motion. Neuromagnetic properties of anticipatory (Contingent Magnetic Variation) and evoked (P200m) brain magnetic fields suggest, respectively, differential allocation of attentional resources by mental imagery instructions (picture vs. body tilt), and a communality of neural structures (in the right centro-parietal region) for the control of both RM and mental rotation processes. Finally, the RM of the body motion is less prone to forward shifts than that of picture motion evidencing an internalization of the implied mass of the virtual body of the observer.

Adult↗
PubMed2005

Vestibular, proprioceptive, and haptic contributions to spatial orientation.

The control and perception of body orientation and motion are subserved by multiple sensory and motor mechanisms ranging from relatively simple, peripheral mechanisms to complex ones involving the highest levels of cognitive function and sensory-motor integration. Vestibular contributions to body orientation and to spatial localization of auditory and visual stimuli have long been recognized. These contributions are reviewed here along with new insights relating to sensory-motor calibration of the body gained from space flight, parabolic flight, and artificial gravity environments. Recently recognized contributions of proprioceptive and somatosensory signals to the appreciation of body orientation and configuration are described. New techniques for stabilizing posture by means of haptic touch and for studying and modeling postural mechanisms are reviewed. Path integration, place cells, and head direction cells are described along with implications for using immersive virtual environments for training geographic spatial knowledge of real environments.

Cognition↗
PubMedDate not supplied

The development of relational landmark use in six- to twelve-month-old infants in a spatial orientation task.

The ability to use the relations between visible landmarks to locate nonvisible goals (allocentric spatial coding) underlies success on a variety of everyday spatial orientation problems. Little is known about the development of true relational coding in infancy. Ninety-six 6-, 8.5- and 12-month-old infants were observed in a peekaboo paradigm in which they had to turn to a target location after displacement to a novel position and direction of facing. In a landmark condition, the target position was located between two landmarks, contrasted with a control condition in which no distinctive landmarks were provided. Six-month-old infants performed poorly in both conditions, 8.5-month-olds were significantly better with the landmarks, and 12-month-olds solved the task with or without landmarks. A follow-up study confirmed that the 8.5-month-olds used both landmarks to solve the task. This demonstration of allocentric spatial coding in 8.5-month-old infants shows earlier competence than that found in previous work in which only infants at the end of the first year were able to use landmarks relationally.

Age Factors↗
PubMed1983

Effects of spatially oriented attention on the facilitation of the H reflex by a cutaneous stimulus.

The effects of spatially oriented attention on the facilitation of the H reflex induced by a mild electrical stimulation of the sural nerve was investigated in 11 human subjects. The H reflex facilitation produced by the cutaneous stimulus was smaller when attention was focused on this stimulus than when it was directed to the same cutaneous field on the opposite leg. This demonstrates that selective attention involves specific descending controls on the spinal circuits mediating the segmental effects of cutaneous afferents.

Afferent Pathways↗
PubMed1994

The effect of spatial orientation on the perception of moving tactile stimuli.

Previous studies have shown that the perception of spatial patterns, such as letters, presented to the hand is affected by the spatial orientation of the hand. The present study investigated how the perception of direction of motion across the fingerpads changes with the position of the hand in space. The moving stimuli were generated on two displays. In one condition, the displays were placed horizontally in front of the subject, with the subject's thumb (target site) and index finger (nontarget site) placed flat on the displays. In a second condition, the displays were vertically oriented and gripped between the thumb and index finger. Using a selective-attention paradigm in which subjects are instructed to respond only to the direction of motion at the target site, performance was still affected by the direction of motion at the nontarget site. Changing the orientation of the displays changed the effectiveness of the nontarget in interfering with the identification of the target movement. Nontarget stimuli that produced no interference in the horizontal orientation did so in the vertical, and vice versa. It appears that subjects are not using the local direction of movement across the fingerpads to judge the relative direction of movement at the two sites; rather, they are using the external direction of movement.

Attention↗
PubMed2001

Reflexive spatial orienting of tactile attention.

We investigated the covert reflexive (exogenous) orienting of tactile spatial attention. Participants made speeded discrimination responses (up vs down) to a series of tactile targets presented randomly to the index finger or thumb of either hand. These targets were preceded at a variable stimulus onset asynchrony (200, 300, or 400 ms) by a spatially nonpredictive tactile cue (presented to both finger and thumb of one or other hand) on either the same or opposite side as the target. Tactile elevation discrimination responses were more rapid and accurate when the cue and target appeared on the same side than when they appeared on opposite sides. Our results provide the first direct empirical evidence that tactile spatial attention can be reflexively directed toward peripheral tactile cues leading to the facilitation of subsequent responses to stimuli presented at that body site.

Adult↗
PubMed2000

Covert visual spatial orienting and saccades: overlapping neural systems.

We used functional magnetic resonance imaging (fMRI) to investigate the functional anatomical relationship between covert orienting of visual spatial attention and execution of saccadic eye movements. Brain areas engaged by shifting spatial attention covertly and by moving the eyes repetitively toward visual targets were compared and contrasted directly within the same subjects. The two tasks activated highly overlapping neural systems and showed that common parietal and frontal regions are more activated during the covert task than the overt oculomotor condition. The possible nature of the relationship between these two operations is discussed.

Adult↗