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.

Modulation of neglect hemianesthesia by transcutaneous electrical stimulation

1996 ◽  
Vol 2 (5) ◽  
pp. 452-459 ◽  
Author(s):  
Giuseppe Vallar ◽  
Maria Luisa Rusconi ◽  
Bruno Bernardini
Keyword(s):  
Electrical Stimulation ◽  
Right Hemisphere ◽  
Internal Representation ◽  
Tactile Perception ◽  
The Body ◽  
Transcutaneous Electrical Stimulation ◽  
Neural Basis ◽  
Left Brain ◽  
Right Brain ◽  
Stimulation Of

AbstractThe effects of transcutaneous electrical stimulation on deficits of tactile perception contralateral to a hemispheric lesion were investigated in 10 right brain-damaged patients and in four left brain-damaged patients. The somatosensory deficit recovered, transiently and in part, after stimulation of the side of the neck contralateral to the side of the lesion, in all 10 patients with lesions in the right hemisphere, both with (six cases) and without (four cases) left visuo-spatial hemineglect, and in one left brain-damaged patient with right hemineglect. In three left brain-damaged patients without hemineglect, the treatment had no detectable effects. In one right brain-damaged patient, the stimulation of the side of the neck ipsilateral to the side of the lesion temporarily worsened the somatosensory deficit. These effects of transcutaneous electrical stimulation are similar to those of vestibular stimulation. The suggestion is made that these treatments modulate, through afferent sensory pathways, higher-order spatial representations of the body, which are pathologically distorted toward the side of the lesion. The modulatory effect is direction-specific: the defective internal representation of the contralesional side may be either partly restored, improving the disorder of tactile perception, or further impoverished, worsening the deficit. The possible neural basis of this modulation is discussed. (JINS, 1996, 2, 452–459.)

scholarly journals Artistic Production Following Brain Damage: A Study of Three Artists

Leonardo ◽  
2011 ◽  
Vol 44 (5) ◽  
pp. 405-410 ◽  
Author(s):  
Anjan Chatterjee ◽  
Bianca Bromberger ◽  
William B. Smith ◽  
Rebecca Sternschein ◽  
Page Widick
Keyword(s):  
Brain Damage ◽  
Right Hemisphere ◽  
Neural Basis ◽  
Left Brain ◽  
Right Hemisphere Damage ◽  
Right Brain ◽  
Art Production ◽  
The Right ◽  
Left Brain Damage ◽  
Insight Into

We know little about the neurologic bases of art production. The idea that the right brain hemisphere is the “artistic brain” is widely held, despite the lack of evidence for this claim. Artists with brain damage can offer insight into these laterality questions. The authors used an instrument called the Assessment of Art Attributes to examine the work of two individuals with left-brain damage and one with right-hemisphere damage. In each case, their art became more abstract and distorted and less realistic. They also painted with looser strokes, less depth and more vibrant colors. No unique pattern was observed following right-brain damage. However, art produced after left-brain damage also became more symbolic. These results show that the neural basis of art production is distributed across both hemispheres in the human brain.

Disconnections in Personal Neglect

2021 ◽  
Author(s):  
Sara Bertagnoli ◽  
Valentina Pacella ◽  
Elena Rossato ◽  
Paul M Jenkinson ◽  
Akaterini Fotopoulou ◽  
...  
Keyword(s):  
White Matter ◽  
Right Hemisphere ◽  
Temporal Cortex ◽  
Lesion Size ◽  
The Body ◽  
Spatial Neglect ◽  
Small Samples ◽  
Motor Deficits ◽  
The Novel ◽  
Extrapersonal Space

Abstract Personal neglect is a disorder in the perception and representation of the body that causes the patients to behave as if the contralesional side of their body does not exist. This clinical condition has not been adequately investigated in the past as it has been considered a symptom of unilateral spatial neglect, which has mainly been studied with reference to extrapersonal space. Only a few studies with small samples have investigated the neuroanatomical correlates of personal neglect, and these have mainly focused on discrete cortical lesions and modular accounts, as well as being based on the hypothesis that this disorder is associated with somatosensory and spatial deficits. In the present study, we tested the novel hypothesis that personal neglect may be associated not only with discrete cortical and subcortical lesions, but also with disconnections of white matter tracts. We performed an advanced lesion analyses in a large sample of 104 right hemisphere damaged patients, 68 of whom were suffering from personal neglect. Results from the analyses of the grey and white matter were controlled for co-occurrent clinical variables such as extrapersonal neglect, anosognosia for hemiplegia and motor deficits, along with other lesion-related variables such as lesion size, the interval from the lesion onset to neuroimaging recordings. Our results reveal that personal neglect is associated with lesions in a medial network which involves the temporal cortex (Heschl’s gyrus), the ventro-lateral nuclei of the thalamus, and the fornix. This suggests that personal neglect involves a convergence between sensorimotor processes, spatial representation and the processing of self-referred information (episodic memory).

Assessing the Neural Basis of Uncertainty in Perceptual Category Learning through Varying Levels of Distortion

2011 ◽  
Vol 23 (7) ◽  
pp. 1781-1793 ◽  
Author(s):  
Reka Daniel ◽  
Gerd Wagner ◽  
Kathrin Koch ◽  
Jürgen R. Reichenbach ◽  
Heinrich Sauer ◽  
...  
Keyword(s):  
Brain Regions ◽  
The Body ◽  
Single Session ◽  
Neural Basis ◽  
Wide Range ◽  
Perceptual Category ◽  
Visuospatial Processing ◽  
Posterior Parietal ◽  
Perceptual Category Learning

The formation of new perceptual categories involves learning to extract that information from a wide range of often noisy sensory inputs, which is critical for selecting between a limited number of responses. To identify brain regions involved in visual classification learning under noisy conditions, we developed a task on the basis of the classical dot pattern prototype distortion task [M. I. Posner, Journal of Experimental Psychology, 68, 113–118, 1964]. Twenty-seven healthy young adults were required to assign distorted patterns of dots into one of two categories, each defined by its prototype. Categorization uncertainty was modulated parametrically by means of Shannon's entropy formula and set to the levels of 3, 7, and 8.5 bits/dot within subsets of the stimuli. Feedback was presented after each trial, and two parallel versions of the task were developed to contrast practiced and unpracticed performance within a single session. Using event-related fMRI, areas showing increasing activation with categorization uncertainty and decreasing activation with training were identified. Both networks largely overlapped and included areas involved in visuospatial processing (inferior temporal and posterior parietal areas), areas involved in cognitive processes requiring a high amount of cognitive control (posterior medial wall), and a cortico-striatal–thalamic loop through the body of the caudate nucleus. Activity in the medial prefrontal wall was increased when subjects received negative as compared with positive feedback, providing further evidence for its important role in mediating the error signal. This study characterizes the cortico-striatal network underlying the classification of distorted visual patterns that is directly related to decision uncertainty.

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 The Neural Basis for Spatial Relations

2010 ◽  
Vol 22 (8) ◽  
pp. 1739-1753 ◽  
Author(s):  
Prin X. Amorapanth ◽  
Page Widick ◽  
Anjan Chatterjee
Keyword(s):  
Brain Damage ◽  
Spatial Information ◽  
Right Hemisphere ◽  
Inferior Frontal Gyrus ◽  
Spatial Relations ◽  
Functional Neuroanatomy ◽  
Neural Basis ◽  
Behavioral Impairment ◽  
Right Brain ◽  
Categorical Spatial Relations

Studies in semantics traditionally focus on knowledge of objects. By contrast, less is known about how objects relate to each other. In an fMRI study, we tested the hypothesis that the neural processing of categorical spatial relations between objects is distinct from the processing of the identity of objects. Attending to the categorical spatial relations compared with attending to the identity of objects resulted in greater activity in superior and inferior parietal cortices (especially on the left) and posterior middle frontal cortices bilaterally. In an accompanying lesion study, we tested the hypothesis that comparable areas would be necessary to represent categorical spatial relations and that the hemispheres differ in their biases to process categorical or coordinate spatial relations. Voxel-based lesion symptom mapping results were consistent with the fMRI observations. Damage to a network comprising left inferior frontal, supramarginal, and angular gyri resulted in behavioral impairment on categorical spatial judgments. Homologous right brain damage also produced such deficits, albeit less severely. The reverse pattern was observed for coordinate spatial processing. Right brain damage to the middle temporal gyrus produced more severe deficits than left hemisphere damage. Additional analyses suggested that some areas process both kinds of spatial relations conjointly and others distinctly. The left angular and inferior frontal gyrus processes coordinate spatial information over and above the categorical processing. The anterior superior temporal gyrus appears to process categorical spatial information uniquely. No areas within the right hemisphere processed categorical spatial information uniquely. Taken together, these findings suggest that the functional neuroanatomy of categorical and coordinate processing is more nuanced than implied by a simple hemispheric dichotomy.

Posterior parietal association cortex of the monkey: command functions for operations within extrapersonal space

1975 ◽  
Vol 38 (4) ◽  
pp. 871-908 ◽  
Author(s):  
V. B. Mountcastle ◽  
J. C. Lynch ◽  
A. Georgopoulos ◽  
H. Sakata ◽  
C. Acuna
Keyword(s):  
Cortical Neurons ◽  
The Body ◽  
Association Cortex ◽  
Active Movement ◽  
Cortical Cells ◽  
Sensory Stimuli ◽  
Passive Rotation ◽  
Extrapersonal Space ◽  
Area 5 ◽  
Posterior Parietal

Experiments were made on the posterior parietal association cortical areas 5 and in 17 hemispheres of 11 monkeys, 6 M. mulatta and 5 M. arctoides. The electrical signs of the activity of single cortical cells were recorded with microelectrodes in waking animals as they carried out certain behavioral acts in response to a series of sensory cues. The behavioral paradigms were one for detection alone, and a second for detection plus projection of the arm to contact a stationary or moving target placed at arm's length. Of the 125 microelectrode penetrations made, 1,451 neurons were identified in terms of the correlation of their activity with the behavioral acts and their sensitivity or lack of it to sensory stimuli delivered passively; 180 were studied quantitatively. The locations of cortical neurons were identified in serial sections; 94 penetrations and 1,058 neurons were located with certainty. About two-thirds of the neurons of area 5 were activated by passive rotation of the limbs at their joints; of these, 82% were related to single, contralateral joints, 10% to two or more contralateral joints, 6% to ipsilateral, and 2% to joints on both sides of the body. A few of the latter were active during complex bodily postures. A large proportion of area 5 neurons were relatively insensitive to passive joint rotations, as compared with similar neurons of the postcentral gyrus, but were driven to high rates of discharge when the same joint was rotated during an active movement of the animal...

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.

Visuo-tactile Integration in Personal Space

2012 ◽  
Vol 24 (3) ◽  
pp. 543-552 ◽  
Author(s):  
Matthew R. Longo ◽  
Jason Jiri Musil ◽  
Patrick Haggard
Keyword(s):  
Posterior Parietal Cortex ◽  
Personal Space ◽  
The Body ◽  
Spatial Constraints ◽  
Left Hand ◽  
Right Hand ◽  
Extrapersonal Space ◽  
Posterior Parietal ◽  
The Right ◽  
Tactile Integration

Integration of information across sensory modalities is enhanced when stimuli in both modalities are in the same location. This “spatial rule” of multisensory integration has been primarily studied in humans by comparing stimuli located either in the same versus opposite side of the body midline or in peripersonal versus extrapersonal space, both of which involve large, categorical differences in spatial location. Here we used psychophysics and ERPs to investigate visuo-tactile integration in personal space (i.e., on the skin surface). We used the mirror box technique to manipulate the congruence of visual and tactile information about which finger on either the right or left hand had been touched. We observed clear compatibility effects for both visual and tactile judgments of which finger on the left hand had been touched. No such effects, however, were found for judgments about the right hand. ERP data showed a similar pattern. Amplitude of the vertex P200 potential was enhanced and that of the N2 was reduced for congruent visuo-tactile events on the left, but not the right, hand. Similarly, a later positivity over posterior parietal cortices (P300) showed contralateral enhancement for congruent visuo-tactile events on both the left and right hands. These results provide clear evidence for spatial constraints on visuo-tactile integration defined in personal space and also reveal clear lateralization of these effects. Furthermore, these results link these “ultraprecise” spatial constraints to processing in the right posterior parietal cortex.

scholarly journals Evidence accumulation relates to perceptual consciousness and monitoring

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Michael Pereira ◽  
Pierre Megevand ◽  
Mi Xue Tan ◽  
Wenwen Chang ◽  
Shuo Wang ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Detection Threshold ◽  
Task Demands ◽  
Neuron Activity ◽  
Neural Responses ◽  
Neuronal Responses ◽  
Neural Basis ◽  
Perceptual Consciousness ◽  
Evidence Accumulation ◽  
Posterior Parietal

AbstractA fundamental scientific question concerns the neural basis of perceptual consciousness and perceptual monitoring resulting from the processing of sensory events. Although recent studies identified neurons reflecting stimulus visibility, their functional role remains unknown. Here, we show that perceptual consciousness and monitoring involve evidence accumulation. We recorded single-neuron activity in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around detection threshold and provided confidence estimates. We find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. We generalize these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. We conclude that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans.

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