Related Experiment Video
Updated: Apr 28, 2026
07:13
A Two-interval Forced-choice Task for Multisensory Comparisons
Published on: November 9, 2018
10.6K
Spatiotemporally varying visual hallucinations: II. Spectral classification and comparison with theory
H Henke1, P A Robinson2, P M Drysdale1
1School Of Physics, The University Of Sydney, Sydney, New South Wales 2006, Australia; Brain Dynamics Center, Westmead Millennium Institute, The University Of Sydney, Westmead, New South Wales 2145, Australia.
Journal of Theoretical Biology
|May 31, 2014
Summary
This study analyzes visual hallucinations, comparing clinical data with a corticothalamic model. Findings suggest hallucinations share features with migraine aura, supporting a corticothalamic origin.
Area of Science:
- Neuroscience
- Visual Perception
- Computational Psychiatry
Background:
- Visual hallucinations are complex phenomena requiring better understanding.
- A recent corticothalamic model predicts spatiotemporally oscillating visual hallucinations.
- Clinical descriptions of hallucinations vary across disorders.
Purpose of the Study:
- To investigate the nature of visual hallucinations.
- To test predictions from a corticothalamic model of visual dynamics.
- To establish boundaries on spatiotemporal frequencies in observed hallucinations.
Main Methods:
- Analysis of clinical descriptions of visual hallucinations.
- Comparison of hallucination features with those during migraine aura.
- Establishing spatiotemporal frequency boundaries for hallucinations.
Main Results:
- Key features of visual hallucinations are consistent with a corticothalamic origin.
- Hallucinations during migraine aura share specific abnormalities with other disorders.
- Quantitative data on temporally oscillating hallucinations is currently limited.
Conclusions:
- The findings support a corticothalamic model for visual hallucinations.
- Migraine aura provides a relevant comparison for understanding visual disturbances.
- Further quantitative research is needed for temporally oscillating hallucinations.
Related Concept Videos
01:24Color Vision
2.0K
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
2.0K
01:26Positive Symptoms Schizophrenia: Hallucinations and Delusions
1.1K
Schizophrenia is a complex psychiatric disorder characterized by a range of symptoms that significantly impact cognition, behavior, and emotional regulation. Among these, the positive symptoms stand out as they involve the addition or exaggeration of normal mental functions, deviating markedly from typical behavior and perception. Hallucinations and delusions are prominent positive symptoms, each profoundly affecting the individual's experience of reality.
Hallucinations
Hallucinations in...
Hallucinations
Hallucinations in...
1.1K
01:22Photoreceptors and Visual Pathways
8.4K
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,...
8.4K
01:26Visual System
2.3K
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...
2.3K
01:24Vision
48.5K
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.
48.5K
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