Related Experiment Video
Updated: Jul 17, 2026
13:00
Measuring Attention and Visual Processing Speed by Model-based Analysis of Temporal-order Judgments
Published on: January 23, 2017
The effect of spatial attention on contrast response functions in human visual cortex
Giedrius T Buracas1, Geoffrey M Boynton
1The Salk Institute, La Jolla, California 92037, USA.
Summary
Spatial attention
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Visual Neuroscience
Background:
- Previous electrophysiology studies suggest spatial attention modulates neuronal firing based on stimulus contrast.
- Models like multiplicative gain or contrast-gain have been proposed to explain this interaction.
- However, these models may not fully capture attention's effect on population-level signals.
Purpose of the Study:
- To investigate the effect of spatial attention on contrast responses in human visual cortex using functional MRI (fMRI).
- To determine if attentional modulation of the blood oxygenation level-dependent (BOLD) signal varies with stimulus contrast.
- To compare the fit of additive, multiplicative, and contrast-gain models to observed BOLD responses.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used to measure brain activity in human participants.
- Participants performed a task involving spatial attention and stimuli of varying contrast.
- BOLD responses in visual areas V1, V2, V3, and MT+ were analyzed.
Main Results:
- Attentional modulation of BOLD responses in visual areas V1, V2, V3, and MT+ showed minimal dependence on stimulus contrast.
- An additive model provided a better description of attentional modulations in V1 compared to multiplicative or contrast-gain models.
- This finding contrasts with previous electrophysiology data on single neuronal firing.
Conclusions:
- The BOLD signal modulation by spatial attention in human visual cortex is largely contrast-invariant.
- An additive model best explains attentional effects on BOLD responses in V1.
- Discrepancies with electrophysiology data highlight the complexity of inferring population-level BOLD signals from single-unit activity.
More Related Videos
07:12A Gaze-Contingent Display Framework for Perceptual Learning Research with Simulated Central Vision Loss
Published on: April 11, 2025
06:46Investigating the Deployment of Visual Attention Before Accurate and Averaging Saccades via Eye Tracking and Assessment of Visual Sensitivity
Published on: March 18, 2019
Related Concept Videos
01:24Vision
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.
01:20Anatomy of the Eyeball
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 layer, the vascular tunic,...
01:26Visual System
Light enters the eye through the cornea, a transparent, dome-shaped surface covering the surface of the eyeball that helps to direct and focus incoming light. This light is then channeled toward the pupil, an adjustable opening whose size is controlled by the iris. The iris, a pigmented muscle, regulates the amount of light entering the eye by contracting or dilating the pupil, thereby ensuring optimal light levels for clear vision.
Once through the pupil, the light passes through the lens, a...
Once through the pupil, the light passes through the lens, a...
01:15Depth Perception and Spatial Vision
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.
01:21Association Areas of the Cortex
Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret information from various sources to enable higher cognitive processes such as memory, learning, and decision-making. Some key association areas include the following:
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...
01:14Motor and Sensory Areas of the Cortex
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.