Related Experiment Video
Updated: Apr 9, 2026
08:42
Monocular Visual Deprivation and Ocular Dominance Plasticity Measurement in the Mouse Primary Visual Cortex
Published on: February 8, 2020
11.5K
Orientation anisotropies in human primary visual cortex depend on contrast.
Ryan T Maloney1, Colin W G Clifford1
1School of Psychology, UNSW Australia, Sydney, NSW, Australia 2052; Colour, Form and Motion Laboratory, School of Psychology, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia 2006; Australian Research Council Centre of Excellence in Vision Science, The University of Sydney, Sydney, New South Wales, Australia 2006.
Neuroimage
|June 21, 2015
Summary
Visual cortex orientation processing shifts from a cardinal bias at low contrast to an oblique bias at high contrast. This adaptive coding strategy in the brain optimizes responses to varying visual input strength.
Area of Science:
- Neuroscience
- Visual Perception
- Computational Neuroscience
Background:
- The visual cortex exhibits orientation processing biases, with traditional views suggesting a cardinal (horizontal/vertical) preference (oblique effect).
- Recent studies indicate an opposing bias towards oblique orientations (horizontal effect), potentially reflecting efficient coding of natural visual environments.
Purpose of the Study:
- To investigate how orientation anisotropies in early visual cortex (V1, V2, V3) change with stimulus contrast.
- To determine if contrast modulates the balance between cardinal and oblique orientation preferences.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to measure brain activity in retinotopically defined early visual areas.
- Participants viewed sinusoidal gratings at varying contrasts and orientations.
Main Results:
- A significant shift in V1 orientation bias was observed: a cardinal bias at low contrast transitioned to an oblique bias at high contrast.
- This contrast-dependent shift was also found in areas V2 and V3 in Experiment 2.
- No consistent radial bias was found in V1 on average, though individual differences existed.
Conclusions:
- Orientation processing in human early visual cortex is adaptive, dynamically adjusting biases based on stimulus contrast.
- This flexibility supports an efficient coding strategy that optimizes neural responses to the strength of incoming visual information.
Related Concept Videos
01:24Vision
61.6K
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.
61.6K
01:20Anatomy of the Eyeball
11.9K
The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle...
11.9K
01:14Motor and Sensory Areas of the Cortex
9.2K
The cerebral cortex, the brain's outermost layer, is pivotal in processing complex cognitive tasks, emotions, and various sensory inputs and executing voluntary motor activities. This intricate structure is divided into three primary functional areas: the motor areas, sensory areas, and association areas.
Motor Areas
The motor areas located in the frontal lobe are central to controlling voluntary movements. This region is further subdivided into the primary motor cortex and the premotor cortex....
Motor Areas
The motor areas located in the frontal lobe are central to controlling voluntary movements. This region is further subdivided into the primary motor cortex and the premotor cortex....
9.2K
01:22Photoreceptors and Visual Pathways
11.2K
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category,...
11.2K
01:32The Retina
78.7K
The retina is a layer of nervous tissue at the back of the eye that transduces light into neural signals. This process, called phototransduction, is carried out by rod and cone photoreceptor cells in the back of the retina.
78.7K
01:15Depth Perception and Spatial Vision
2.7K
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
2.7K