Globs are millimeter-sized color modules found beyond the visual area V2 in the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

's color processing

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

(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 ...

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 hues 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 represe ...

. The term "glob" was proposed by Bevil Conway and Doris Tsao on an analogy with the cytochrome-oxidase blobs 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. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

such as face patches, and inferior temporal feature columns.

Properties

Globs are found in the V4 complex, a region in the inferior temporal cortex, forward of area V3.This complex 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 The fus ...

part of the posterior inferior temporal cortex and the rear part of the inferior temporal near the occipital lobe known as 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 and single-unit recording.

Color perception

Three types of retinal

cone In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the '' apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines ...

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 (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

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, Anatomical ter ...

, 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 thre ...

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 hue 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