What Spatial Frames of Reference are Used to Guide Off-Axis Aiming?

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 364-364
Author(s):  
P T Sowden ◽  
I R L Davies ◽  
S K Boyles ◽  
T J Simpson ◽  
L A Skinner
Keyword(s):  
Closed Loop ◽  
General Information ◽  
The Body ◽  
Frames Of Reference ◽  
Absolute Space ◽  
Laser Pointer ◽  
Spatial Frames Of Reference ◽  
Preliminary Model ◽  
Correction System ◽  
Aiming Performance

What spatial frames of reference are used to guide body centred actions such as pointing and aiming? Do observers learn to use body-scaled frames of reference with specific points of origin (eg hip vs shoulder)? Do they extrapolate general information about body scaling? Do they learn about the position of the body (and its individual parts) in absolute space? We investigated these questions using two kinds of aiming: off-axis aiming vs along-axis aiming. Subjects aimed a ‘gun’ (a laser pointer mounted at the end of a stick with a button at the other end) at various targets under three conditions. They practised aiming in one position for 60 ‘shots’ and then changed to a new position and completed another 60 shots. Transfer across position of ‘gun’ in absolute space, across position of body in absolute space, and across position of gun relative to body were assessed. Results suggested that off-axis aiming was controlled by a closed-loop error correction system requiring sight of results for learning to occur. Further, changes in the position of the body in absolute space (from kneeling to standing or vice versa) led to the worst aiming performance. Changes in gun position relative to the body or in absolute space had less effect on aiming accuracy, which suggests that it is not dependent on specific learned sensory - motor linkages. On the basis of these results we propose a preliminary model for off-axis training.

scholarly journals Mild Stroke Affects Pointing Movements Made in Different Frames of Reference

2021 ◽  
pp. 154596832198934
Author(s):  
Fariba Hasanbarani ◽  
Marc Aureli Pique Batalla ◽  
Anatol G. Feldman ◽  
Mindy F. Levin
Keyword(s):  
Degrees Of Freedom ◽  
Peripersonal Space ◽  
The Body ◽  
Frames Of Reference ◽  
Rehabilitation Programs ◽  
Spatial Frames Of Reference ◽  
Complex Process ◽  
Sensorimotor Impairment ◽  
Mild Stroke ◽  
Made In

Background Motor performance is a complex process controlled in task-specific spatial frames of reference (FRs). Movements can be made within the framework of the body (egocentric FR) or external space (exocentric FR). People with stroke have impaired reaching, which may be related to deficits in movement production in different FRs. Objective To characterize rapid motor responses to changes in the number of degrees of freedom for movements made in different FRs and their relationship with sensorimotor and cognitive impairment in individuals with mild chronic stroke. Methods Healthy and poststroke individuals moved their hand along the contralateral forearm (egocentric task) and between targets in the peripersonal space (exocentric task) without vision while flexing the trunk. Trunk movement was blocked in randomized trials. Results For the egocentric task, controls produced the same endpoint trajectories in both conditions (free- and blocked-trunk) by preserving similar shoulder-elbow interjoint coordination (IJC). However, endpoint trajectories were dissimilar because of altered IJC in stroke. For the exocentric task, controls produced the same endpoint trajectories when the trunk was free or blocked by rapidly changing the IJC, whereas this was not the case in stroke. Deficits in exocentric movement after stroke were related to cognitive but not sensorimotor impairment. Conclusions Individuals with mild stroke have deficits rapidly responding to changing conditions for complex reaching tasks. This may be related to cognitive deficits and limitations in the regulation of tonic stretch reflex thresholds. Such deficits should be considered in rehabilitation programs encouraging the reintegration of the affected arm into activities of daily living.

scholarly journals Spatial frames of reference and somatosensory processing: a neuropsychological perspective

1997 ◽  
Vol 352 (1360) ◽  
pp. 1401-1409 ◽  
Author(s):  
Giuseppe Vallar
Keyword(s):  
Right Hemisphere ◽  
Higher Order ◽  
The Body ◽  
Frames Of Reference ◽  
Neural Basis ◽  
Right Brain ◽  
Extrapersonal Space ◽  
Spatial Frames Of Reference ◽  
Posterior Parietal ◽  
Sensory Processes

In patients with lesions in the right hemisphere, frequently involving the posterior parietal regions, left–sided somatosensory (and visual and motor) deficits not only reflect a disorder of primary sensory processes, but also have a higher–order component related to a defective spatial representation of the body. This additional factor, related to right brain damage, is clinically relevant: contralesional hemianaesthesia (and hemianopia and hemiplegia) is more frequent in right brain–damaged patients than in patients with damage to the left side of the brain. Three main lines of investigation suggest the existence of this higher–order pathological factor. (i) Right brain–damaged patients with left hemineglect may show physiological evidence of preserved processing of somatosensory stimuli, of which they are not aware. Similar results have been obtained in the visual domain. (ii) Direction–specific vestibular, visual optokinetic and somatosensory or proprioceptive stimulations may displace spatial frames of reference in right brain–damaged patients with left hemineglect, reducing or increasing the extent of the patients’ ipsilesional rightward directional error, and bring about similar directional effects in normal subjects. These stimulations, which may improve or worsen a number of manifestations of the neglect syndrome (such as extrapersonal and personal hemineglect), have similar effects on the severity of left somatosensory deficits (defective detection of tactile stimuli, position sense disorders). However, visuospatial hemineglect and the somatosensory deficits improved by these stimulations are independent, albeit related, disorders. (iii) The severity of left somatosensory deficits is affected by the spatial position of body segments, with reference to the midsagittal plane of the trunk. A general implication of these observations is that spatial (non–somatotopic) levels of representation contribute to corporeal awareness. The neural basis of these spatial frames includes the posterior parietal and the premotor frontal regions. These spatial representations could provide perceptual–premotor interfaces for the organization of movements (e.g. pointing, locomotion) directed towards targets in personal and extrapersonal space. In line with this view, there is evidence that the sensory stimulations that modulate left somatosensory deficits affect left motor disorders in a similar, direction–specific, fashion.

Individual Differences in the Flexibility of Peripersonal Space

2017 ◽  
Vol 64 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Samuel B. Hunley ◽  
Arwen M. Marker ◽  
Stella F. Lourenco
Keyword(s):  
Individual Differences ◽  
Peripersonal Space ◽  
The Body ◽  
Laser Pointer ◽  
Baseline Measure ◽  
Bisection Task ◽  
Defensive Function ◽  
Representational Space ◽  
Laser Condition ◽  
Line Bisection Task

Abstract. The current study investigated individual differences in the flexibility of peripersonal space (i.e., representational space near the body), specifically in relation to trait claustrophobic fear (i.e., fear of suffocating or being physically restricted). Participants completed a line bisection task with either a laser pointer (Laser condition), allowing for a baseline measure of the size of one’s peripersonal space, or a stick (Stick condition), which produces expansion of one’s peripersonal space. Our results revealed that individuals high in claustrophobic fear had larger peripersonal spaces than those lower in claustrophobic fear, replicating previous research. We also found that, whereas individuals low in claustrophobic fear demonstrated the expected expansion of peripersonal space in the Stick condition, individuals high in claustrophobic fear showed less expansion, suggesting decreased flexibility. We discuss these findings in relation to the defensive function of peripersonal space and reduced attentional flexibility associated with trait anxieties.

A Closed-Loop Optical Scan Correction System for Scanning Probe Microscopes

1994 ◽  
pp. 437-445 ◽  
Author(s):  
Daniel R. Marshall ◽  
Eric M. Fray ◽  
James D. Mueller ◽  
L. Martin Courtney ◽  
John C. Podlesny ◽  
...  
Keyword(s):  
Closed Loop ◽  
Scanning Probe ◽  
Optical Scan ◽  
Correction System

Predictive Value of The Combined Detection of Platelets, D-Dimer, and Procalcitonin On Severe Heat Stroke

2021 ◽  
Author(s):  
wang lei ◽  
jiang dai shan ◽  
zhang Yi ◽  
jia han yu ◽  
shen jun hua
Keyword(s):  
Body Temperature ◽  
Characteristic Curve ◽  
Heat Stroke ◽  
Area Under The Curve ◽  
General Information ◽  
The Body ◽  
Control Group ◽  
Clinical Test ◽  
Roc Curve Analysis ◽  
Combined Detection

Abstract BackgroundTo explore the clinical characteristics of patients with severe heat stroke, we explored the early sensitive indicators of heat stroke (HS) patients, with a view to early intervention for HS patients. MethodsFrom July 30, 2015 to October 5, 2020, 70 inpatients with severe heat stroke admitted to the Second Affiliated Hospital of Nantong University, Jiangsu Province were selected as the research objects. The general information and clinical test indicators of the patients were recorded, and all patients were assessed for acute physiology (APACH Ⅱ) upon admission. According to the severity of heatstroke, they were divided into three groups: control group (heat cramps and heat exhaustion), EHS, and CHS to compare the differences in indicators of each group. Further draw the receiver operating characteristic curve (ROC).Results1. According to the severity of heat stroke, 28 cases were divided into the control group, 24 cases in the EHS group, and 18 cases in the CHS group. The body temperature of the EHS group and the CHS group was significantly higher than that of the control group (both P<0.05), but there was no statistical difference in the body temperature of the EHS group and the CHS group; the DD, PCT, and APACH of the EHS group were significantly higher than those of the control group and the CHS group (both P＜0.05); PLT, CRP, Na, GLU of EHS group were lower than those of control group and CHS group (all P＜0.05), and the decrease of PLT was more significant; CHS group HbA1C was significantly higher than that of control group and EHS group (all P <0.05). 2. ROC curve analysis the areas under the curves of DD, PCT, and PLT are 0.670, 0.705, 0.791, respectively, the sensitivity is 40.48%, 100%, 73.81%, and the specificity is 96.43%, 32.14%, 78.57%, respectively. Using the combined analysis of the three series tests, the area under the curve was 0.838, the sensitivity was 71.43%, and the specificity was 85.71%. ConclusionsEHS patients have higher DD, PCT, APACH, but PLT, CRP, Na, and blood sugar are lower. At the same time, the significant decrease of PLT and the increase of PCT and DD may be early sensitive indicators of HS. The combined detection of the three can be used as a reference basis for early diagnosis of HS and critical illness.

Egocentric Action in Early Infancy: Spatial Frames of Reference for Saccades

1997 ◽  
Vol 8 (3) ◽  
pp. 224-230 ◽  
Author(s):  
Rick O. Gilmore ◽  
Mark H. Johnson
Keyword(s):  
Spatial Information ◽  
Visual Space ◽  
Frames Of Reference ◽  
Saccade Target ◽  
Visually Guided ◽  
Retinal Position ◽  
Position Information ◽  
Visual Spatial ◽  
Visually Guided Action ◽  
Spatial Frames Of Reference

The extent to which infants combine visual (i e, retinal position) and nonvisual (eye or head position) spatial information in planning saccades relates to the issue of what spatial frame or frames of reference influence early visually guided action We explored this question by testing infants from 4 to 6 months of age on the double-step saccade paradigm, which has shown that adults combine visual and eye position information into an egocentric (head- or trunk-centered) representation of saccade target locations In contrast, our results imply that infants depend on a simple retinocentric representation at age 4 months, but by 6 months use egocentric representations more often to control saccade planning Shifts in the representation of visual space for this simple sensorimotor behavior may index maturation in cortical circuitry devoted to visual spatial processing in general

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