Related Experiment Video
Updated: May 22, 2026
11:24
Targeted Labeling of Neurons in a Specific Functional Micro-domain of the Neocortex by Combining Intrinsic Signal and Two-photon Imaging
Published on: December 12, 2012
Comment on "Universality in the evolution of orientation columns in the visual cortex"
Yicong Meng1, Shigeru Tanaka, Chi-Sang Poon
1Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (New York, N.Y.)
|April 28, 2012
Summary
A universal constant for pinwheel density in mammalian brains is disputed. A simpler brain size-pinwheel density scaling law better predicts orientation maps across species.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Systems Neuroscience
Background:
- The organization of orientation maps in the mammalian visual cortex is a fundamental question in neuroscience.
- Kaschube et al. proposed a model predicting a universal constant (π) for pinwheel density based on long-range connectivity.
Purpose of the Study:
- To challenge the conclusions of Kaschube et al. regarding universal pinwheel density.
- To propose an alternative model explaining orientation map organization.
Main Methods:
- Analysis of pinwheel density data from three mammalian species.
- Comparison of a proposed brain size-pinwheel density scaling law against existing models.
Main Results:
- The universal constant of π for pinwheel density is not supported.
- A simple scaling law relating brain size and pinwheel density effectively predicts orientation map organization.
Conclusions:
- The proposed brain size-pinwheel density scaling law offers a more parsimonious explanation for orientation maps.
- This finding has implications for understanding self-organized and disorganized neural structures in the visual cortex.
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.
01:22Photoreceptors and Visual Pathways
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, whereas...
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...
01:20Anatomy 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,...
01:23Criticisms of the Evolutionary Perspective
In a study where individuals posing as strangers offered compliments and proposed casual sex to students, the responses differed significantly based on gender. Not a single woman accepted the proposal, while 70% of the men agreed. This outcome provides a useful scenario to explore through the lens of evolutionary psychology and social learning theory, highlighting the diverse perspectives on human sexual behaviors.
Evolutionary psychology provides one explanation for these findings, suggesting...
Evolutionary psychology provides one explanation for these findings, suggesting...
01:11Sensory Perception: Organization of the Somatosensory System
The somatosensory system is the central and peripheral nervous system component that senses and processes touch, pressure, pain, temperature, and body position or proprioception. The process of sensation takes place at three levels:
The receptor level:
The receptor level is the first stage of sensation. It involves the detection of a stimulus by specialized sensory receptors. The stimulus must arrive within the receptor's receptive field. Next, the receptor converts the energy of the stimulus...
The receptor level:
The receptor level is the first stage of sensation. It involves the detection of a stimulus by specialized sensory receptors. The stimulus must arrive within the receptor's receptive field. Next, the receptor converts the energy of the stimulus...