Globs are millimeter-sized color modules found beyond the

visual area V2 The visual cortex of the brain is the area of the cerebral cortex that processes visual perception, visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in ...

in the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

's color processing

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

(also known as parvocellular) pathway. They are scattered throughout the posterior

inferior temporal cortex The inferior temporal gyrus is one of three gyri of the temporal lobe and is located below the middle temporal gyrus, connected behind with the inferior occipital gyrus; it also extends around the infero-lateral border on to the inferior surface o ...

in an area called the V4 complex. They are clustered by color preference, and organized as color

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...

s. They are the first part of the brain in which color is processed in terms of the full range of

hue In color theory, hue is one of the main properties (called Color appearance model#Color appearance parameters, color appearance parameters) of a color, defined technically in the CIECAM02 model as "the degree to which a Stimulus (physiology ...

s found in

color space A color space is a specific organization of colors. In combination with color profiling supported by various physical devices, it supports reproducible representations of colorwhether such representation entails an analog or a digital represent ...

. The term "glob" was proposed by

Bevil Conway Bevil Conway (born 4 November 1974, in Harare, Zimbabwe) is a neuroscientist and artist, and an expert in color. Conway specialises in visual perception in his scientific work, and he often explores the limitations of the visual system in his a ...

and

Doris Tsao Doris Ying Tsao is an American systems neuroscientist and professor of biology at the University of California, Berkeley. She was formerly on the faculty at the California Institute of Technology. She is recognized for pioneering the use of fMRI ...

on an analogy with the cytochrome-oxidase

blob Blob may refer to: Science Computing * Binary blob, in open source software, a non-free object file loaded into the kernel * Binary large object (BLOB), in computer database systems * A storage mechanism in the cloud computing platform Mic ...

s of V1, an earlier stage in the hierarchical elaboration of color. This also distinguishes them from other types of modules found elsewhere in the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...

such as face patches, and inferior temporal feature columns.

Properties

Globs are found in the V4 complex, an area in the inferior temporal cortex, forward of area V3, that includes areas V4, the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

part of the posterior inferior temporal cortex and the rear part of the inferior temporal near the occipital lobe called TEO. Their neurons are not restricted to a single color preference. Neurons in adjacent glob cells have similar color tuning and form clusters that are arranged spatially within the cortex. In between them are ‘‘interglob’’ areas that were not color sensitive but respond to shape. The color-tuned neurons are arranged in color columns that are of a finer scale than single globs. These columns are between 50 and 100 μm in size. Color preferences of neurons recorded sequentially along given columns are arranged according to a chromotopic map that reflects perceptual

. They are studied using

functional MRI Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...

and

single-unit recording In neuroscience, single-unit recordings provide a method of measuring the electro-physiological responses of a single neuron using a microelectrode system. When a neuron generates an action potential, the signal propagates down the neuron as a cu ...

Color perception

Three types of retinal

cone A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines con ...

create signals that get transformed in the visual pathway to create the perception of color. However the neurons processing them in the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

lateral geniculate nucleus In neuroanatomy, the lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a structure in the thalamus and a key component of the mammalian visual pathway. It is a small, ovoid, ventral projec ...

, and V1 and V2 early parts of the visual cortex encode using the

opponent process The opponent process is a color theory that states that the human visual system interprets information about color by processing signals from photoreceptor cells in an antagonistic manner. The opponent-process theory suggests that there are thr ...

only a limited range of colors that does not reflect the dimensions of perceptual color space. It is only the next area where globs are found that along the visual processing hierarchy, show

sensitivity, with the population of neurons representing most (if not all) of perceptual color space and which the color responses of neurons correspond to perception.

References

{{reflist Color Color space Visual perception Visual system