People are intuitive physicists, knowing from birth how objects under the influence of gravity are likely to fall, topple or roll. In a new study, scientists have found the brain cells apparently responsible for this innate wisdom.
In a part of the brain responsible for recognizing color, texture and shape, Johns Hopkins University researchers found neurons that used large-scale environmental cues to infer the direction of gravity. The findings, forthcoming this month in the journal Current Biology, and just posted online, suggest these cells help humans orient themselves and predict how objects will behave.
"Gravity is a strong ubiquitous force in our world," said senior author Charles E. Connor, a professor of neuroscience and director of the university's Zanvyl Krieger Mind/Brain Institute. "Our results show how the direction of gravity can be derived from visual cues, providing critical information about object physics as well as additional cues for maintaining posture and balance."
Connor, along with lead author Siavash Vaziri, a former Johns Hopkins postdoctoral fellow, studied individual cells in the object area of the rhesus monkey brain, a remarkably close model for the organization and function of human vision. They measured responses of each cell to about 500 abstract three-dimensional shapes presented on a computer monitor. The shapes ranged from small objects to large landscapes and interiors.
They found that a given cell would respond to many different stimuli, especially large planes and sharp, extended edges. What tied these stimuli together was their alignment in the same tilted rectilinear reference frame. These cells, sensitive to different tilts, could provide a continuous signal for the direction of gravity, even as a person constantly moves.
In other words, Connor said, these neurons could help people understand which way is up.
"The world does not appear to rotate when the head tilts left or right or gaze tilts up or down, even though the visual image changes dramatically," he said. "That perceptual stability must depend on signals like these that provide a constant sense of how the visual environment is oriented."
The researchers' initial discovery of cells sensitive to large-scale shape, reported in Neuron in 2014, was surprising because they found them in a brain region long regarded as dedicated exclusively to object vision. The new findings make sense of this anatomical juxtaposition, since knowing the gravitational reference frame is critical for predicting how objects will behave.
"When we dive after a ball in tennis, the whole visual world tilts, but we maintain our sense of how the ball will fall and how to aim our next shot," Connor said. "The visual cortex generates an incredibly rich understanding of object structure, materials, strength, elasticity, balance, and movement potential. These are the things that make us such expert intuitive physicists."
The study was supported by National Institutes of Health grant EY024028.
Jill Rosen | EurekAlert!
The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine