At the Weizmann Institute of Science, researchers explored these questions by attaching plastic “whiskers” to the fingers of blindfolded volunteers and asking them to carry out a location task. The findings, which recently appeared in The Journal of Neuroscience, have yielded new insight into the process of sensing, and they may point to new avenues in developing aids for the blind.
The scientific team, including Dr. Avraham Saig, Dr. Goren Gordon, and Eldad Assa in the group of Prof. Ehud Ahissar and Dr. Amos Arieli, all of the Department of Neurobiology, attached a “whisker” – a 30-cm-long elastic “hair” with position and force sensors on its base – to the index finger of each hand of a blindfolded subject. Then, two poles were placed at arm’s distance on either side and slightly to the front of the seated subject, with one a bit farther back than the other. Using just their whiskers, the subjects were challenged to figure out which pole – left or right – was further back. As the experiment continued, the displacement between front and back poles was reduced, up to the point where the subject could no longer distinguish front from back.
On the first day of the experiment, subjects picked up the new sense so well that they could correctly identify a pole that was set back by only eight cm. An analysis of the data revealed that the subjects did this by figuring the spatial information from the sensory timing. That is, moving their bewhiskered hands together, they could determine which pole was the back one because the whisker on that hand made contact earlier.
When they repeated the testing the next day, the researchers discovered that the subjects had improved their whisking skills significantly: The average sensory threshold went down to just three cm, with some being able to sense a displacement of just one cm. Interestingly, the ability of the subjects to sense time differences had not changed over the two days. Rather, they had improved in the motor aspects of their whisking strategies: Slowing down their hand motions – in effect lengthening the delay time – enabled them to sense a smaller spatial difference.
Says Dr. Saig: “We know that our senses are linked to muscles, for example ocular and hand muscles. In order to sense the texture of cloth, for example, we move our fingers across it, and to see a stationary object, our eyes must be in constant motion. In this research, we see that changing our physical movements alone – without any corresponding change in the sensitivity of our senses – can be sufficient to sharpen our perception.”
Based on the experiments, the scientists created a statistical model to describe how the subjects updated their “world view” as they acquired new sensory information – up to the point where they were confident enough to rely on that sense. The model, based on principles of information processing, could explain the number of whisking movements needed to arrive at the correct answer, as well as the pattern of scanning the subjects employed – a gradual change from long to short movements. With this strategy, the flow of information remains constant. “The experiment was conducted in a controlled manner, which allowed us direct access to all the relevant variables: hand motion, hand-pole contact, and the reports of the subjects themselves,” says Dr. Gordon. “Not only was there a good fit between the theory and the experimental data, we obtained some useful quantitative information on the process of active sensing.”
“Both sight and touch are based on arrays of receptors that scan the outside world in an active manner,” says Prof. Ahissar. “Our findings reveal some new principles of active sensing, and show us that activating a new artificial sense in a ‘natural’ way can be very efficient.” Arieli adds: “Our vision for the future is to help blind people ‘see’ with their fingers. Small devices that translate video to mechanical stimulation, based on principles of active sensing that are common to vision and touch, could provide an intuitive, easily used sensory aid.”
Prof. Ehud Ahissar’s research is supported by the Murray H. and Meyer Grodetsky Center for Research of Higher Brain Functions; the Jeanne and Joseph Nissim Foundation for Life Sciences Research; the Kahn Family Research Center for Systems Biology of the Human Cell; Lord David Alliance, CBE; the Berlin Family Foundation; Jack and Lenore Lowenthal, Brooklyn, NY; Research in Memory of Irving Bieber, M.D. and Toby Bieber, M.D.; the Harris Foundation for Brain Research; and the Joseph D. Shane Fund for Neurosciences. Prof. Ahissar is the incumbent of the Helen Diller Family Professorial Chair in Neurobiology.
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,700 scientists, students, technicians, and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials, and developing new strategies for protecting the environment.
Jennifer Manning | Newswise Science News
A novel synthetic antibody enables conditional “protein knockdown” in vertebrates
20.08.2018 | Technische Universität Dresden
Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
20.08.2018 | Information Technology
20.08.2018 | Life Sciences
20.08.2018 | Information Technology