Apparently not, say researchers at the Hebrew University of Jerusalem and Hadassah Hospital-Mount Scopus. The space within reach of our hands — where actions such as grasping and touching occur — is known as the “action space.”
Research has shown that visual information in this area is organized in hand-centered coordinates — in other words, the representation of objects in the human brain depends on their spatial position with respect to the hand.
According to new research published in Psychological Science, a journal of the Association for Psychological Science, amputation of the hand results in distorted visuospatial perception of the action space. The article was written by neuroscientists Dr. Tamar R. Makin, Meytal Wilf and Dr. Ehud Zohary of the Alexander Silberman Institute of Life Sciences at the Hebrew University of Jerusalem along with Dr. Isabella Schwartz of Hadassah Mount Scopus Hospital in Jerusalem.
They sought to investigate how hand amputations affect visuospatial perception in near space. Volunteers with either left- or right-hand amputations participated in this experiment. They were instructed to look at a central cross on a screen while two white squares were briefly shown to the left and right side of the cross. The volunteers had to indicate which of the squares was farther away from the cross.
The results reveal that hand amputations affect visuospatial perception. When the right square was slightly farther away from the center, participants with right-hand amputations tended to perceive it as being at the same distance from the center as the left square; this suggests that these volunteers underestimated the distance of the right square relative to the left. Conversely, when the left square was farther away, left-hand amputees perceived both squares as being equally far away from the center — these participants underestimated the left side of near space.
Interestingly, when the volunteers were seated farther away from the screen, they were more accurate in judging the distances, indicating that hand amputations may only affect perception of the space close to the body.
The findings suggest that losing a hand may shrink the action space on the amputated side, leading to permanent distortions in spatial perception. According to the researchers, “This shows that the possibility for action in near space shapes our perception — the space near our hands is really special, and our ability to move in that space affects how we perceive it.”
The researchers note that these results have implications for spatial hemineglect — a condition (often following brain injury) in which the patient cannot perceive objects on one side of space. This condition is very often associated with paralysis of the hand in the neglected side, which, based on the current study, might exasperate the perceptual neglect.
The authors suggest that, based on their findings, “current rehabilitation approaches that emphasize action on the affected side may reverse this process.” For example, encouraging the use of the affected hand or by providing visual feedback (through prism adaptation or mirrors) may help overcome hemineglect by increasing the size of the action space on the affected side.
For further information: Dept. of Media Relations, the Hebrew University,
Tel: 02-588-2875. Orit Sulitzeanu, Hebrew University spokesperson, Tel: 02-5882811
Orit Sulitzeanu | Hebrew University
Investigators may unlock mystery of how staph cells dodge the body's immune system
22.09.2017 | Cedars-Sinai Medical Center
Monitoring the heart's mitochondria to predict cardiac arrest?
21.09.2017 | Boston Children's Hospital
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy