Color center and Oklahoma Department of Insurance

Contents 1 Primary visual cortex 2 Higher order visual processing 2.1 Visual area V4 2.2 V4α 2.3 V4-V4α complex 2.4 V2 prestriate cortex 3 Research Methods 4 Cerebral achromotopsia 5 See also 6 References

Primary visual cortex

The primary visual cortex, also called V1, is located in the calcarine fissure, and is the first step in visual processing. It receives visual input from the lateral geniculate nucleus, which is located in the thalamus. V1 sends the visual information received from the LGN to other extrastriate cortex areas for higher order processing. This higher order processing includes the recognition of shapes, motion, and color.

V1 has multiple areas that are color sensitive, which indicates that color processing is not limited to one area. According to a paper by Dr. Robert Shapley, V1 has an important role in color perception. fMRI experimental results showed that V1 has two kinds of color sensitive neurons: single-opponent and double-opponent cells. These cells are integral in the opponent process of interpreting color signals. Single-opponent neurons respond to large areas of color. This is advantageous for recognizing large color scenes and atmospheres. In comparison, double opponent cells respond to patterns, textures, and color boundaries. This is more important for perceiving the color of objects and pictures. The double-opponent cells are receptive to opposite inputs from different cone cells in the retina. This is ideal for identifying contrasting colors, such as red and green. Double-opponent cells are particularly important in computing local cone ratios from visual information from their receptive fields.

Single opponent color sensitive neurons can be divided into two categories depending on the signals they receive from the cone cells: L-M neurons and S/(L+M) neurons. The three types of cone cells, small (S), medium (M), and long (L), detect different wavelengths across the visible spectrum. S cone cells can see short wavelength colors, which corresponds to violet and blue. Similarly, M cells detect medium wavelength colors, such as green and yellow, and L cells detect long wavelength colors, like red. L-M neurons, also called red-green opponent cells, receive input from long wavelength cones opposed by input from medium wavelength cones. S/(L+M) neurons receive input from S-cells and is opposed by a sum of the L and M-cell inputs. S/(L+M) neurons are also called blue-yellow opponent cells. The opposition between the colors allows the visual system to interpret differences in color, which is ultimately more efficient than processing colors separately. Higher order visual processing A visual field map of the primary visual cortex and the numerous extrastriate areas.

The primary visual cortex V1 sends visual information to the extrastriate cortical areas for higher order visual processing. These extrastriate cortical areas are located anterior to the occipital lobe. The main ones are designated as visual areas V2, V3, V4, and V5/MT. Each area can have multiple functions. Recent findings have shown that the color center is neither isolated nor traceable to a single area in the visual cortex. Rather, there are multiple areas that possibly have different roles in the ability to process color stimulus. Visual area V4 The lingual gyrus is the hypothetical location of V4 in macaque monkeys. In humans, this area is called hV4. The fusiform gyrus is the hypothetical location of V4α, a secondary area for color processing.

Anatomical and physiological studies have established that the color center begins in V1 and sends signals to extrastrate areas V2 and V4 for further processing. V4 in particular is an area of interest because of the strength of the color receptive fields in its neurons. V4 was initially identified in macaque monkey visual cortex experiments. Originally, it was proposed that color was selectively processed in V4. However, this hypothesis was later rejected in favor of another hypothesis which suggested that V4 and other areas around V4 work together to process color in the form of multiple color selective regions. After identification of V4 as the color selective region in macaque monkeys, scientists began searching for a homologous structure in the human cortex. Using fMRI brain imaging, scientists found three main areas stimulated by color: V1, an area in the ventral occipital lobe, specifically the lingual gyrus, which was designated as human V4, or hV4, and another area located anteriorly in the fusiform gyrus, designated as V4α.

The purpose of V4 has changed dynamically as new studies are performed. Since V4 responds strongly to color in both macque monkeys and humans, it has become an area of interest to scientists. The V4 area was originally attributed to color selectivity, but new evidence has shown that V4, as well as other areas of the visual cortex, are receptive to various inputs. V4 neurons are receptive to a number of properties, such as color, brightness, and texture. It is also involved in processing shape, orientation, curvature, motion, and depth.

The actual organization of hV4 in the cortex has yet to be determined, but is being investigated. In the macaque monkey, V4 spans the dorsal and ventral occipital lobe. Human experiments have shown that V4 only spans the ventral portion. This led to distinguishing hV4 from the macaque V4. A recent study from Winawer et al. analyzing fMRI measurements to map the hV4 and ventral occipital areas showed variances between subjects used for hV4 mapping was at first attributed to instrumentation error, but Winawer argued that the sinuses in the brain interfered with fMRI measurements. Two models for hV4 were tested: one model had hV4 completely in the ventral side, and the second model had hV4 split into dorsal and ventral sections. It was concluded that it was still difficult to map the activity of hV4, and that further investigation was required. However, other evidence, such as lesions in the ventral occipital lobe causing achromatopsia, suggested that the VO area plays an important role in color vision. V4α

The search for the human equivalent of V4 led to the discovery of other areas that were stimulated by color. The most significant was an area anterior in the ventral occipital lobe, subsequently named V4α. Further fMRI experiments found that V4α had a different function than V4, but worked cooperatively with it. V4α is involved in a number of processes, and is active during tasks requiring color ordering, imagery, knowledge about color, color illusions, and object color. V4-V4α complex

The V4 and V4α areas are separate entities, but because of their close proximity in the fusiform gyrus, these two areas are often collectively called the V4-complex. Research into the V4-complex discovered that different chromatic stimulations activated either the V4 or the V4α area, and some stimulation parameters activated both. For example, naturally colored images activated V4α more powerfully than V4. Unnaturally colored images activated both V4α and V4 equally. It was concluded that the two sub-divisions cooperate with each other in order to generate color images, but they are also functionally separate.

An interesting study from Nunn et al. on the activation of the V4-complex in people with visual synesthesia from hearing spoken words was used to predict the location of the color center. Synesthesia is the phenomenon where a sensory stimulus produces an automatic and involuntary reaction in a different sensation. In this study, people who would see colors upon hearing words were studied to see if the color reaction could be traced to a specific cortical area. fMRI results showed that the left fusiform gyrus, an area consistent with V4, was activated when the subjects spoke. They also found a simultaneous activation of V4α. Interestingly, there was little activity in areas V1 and V2. These results validated the existence of the V4-complex in humans as an area specialized for color vision. V2 prestriate cortex

V2, also called the prestriate cortex, is believed to have a small role in color processing by projecting signals from V1 to the V4-complex. Whether or not color selective cells are present in V2 is still being investigated. Some optical imaging studies have found small clusters of red-green color selective cells in V1 and V2, but not any blue-yellow color selective cells. Other studies have shown that V2 is activated by color stimuli, but not color after images. V4 also has feedback on V2, suggesting that there is a defined network of communication between the multiple areas of the visual cortex. When GABA, an inhibitory neurotransmitter, was injected into V4 cells, V2 cells experienced a significant decrease in excitability. Research Methods fMRI showing activity in the primary visual cortex V1.

Functional magnetic resonance imaging, or fMRI for short, has been key in determining the color selective regions in the visual cortex. fMRI is able to track brain activity by measuring blood flow throughout the brain. Areas that have more blood flowing to them indicates an occurrence of neuronal activity. This change in blood flow is called

Oklahoma Department of Insurance and Color center

The current Insurance Commissioner is John D. Doak. John Doak was sworn in as Oklahoma’s 12th Insurance Commissioner on Jan. 10, 2011.

Contents 1 Responsibilities 2 Budget 3 Organization 4 Staffing 5 See also 6 References 7 External links

Responsibilities

OID is responsible for regulating and reviewing all insurance companies within Oklahoma to make sure they are solvent and comply with all insurance laws and regulations. The Department also educates consumers about insurance by publishing information and rate guides on all kinds of insurance coverage. It also is responsible for helping consumers when they have disputes with insurance companies.

One of the chief duties of the Department is to register and license agents who sell insurance products. The Department also requires agents to meet ongoing continuing education requirements. Other professions regulated by the Department include bail bondsmen, real estate appraisers, funeral directors, and insurance adjusters. Budget

The revenue for Oklahoma Insurance Department's budget is generated primarily from the fees associated with the licenses. For the fiscal year 2009-2010, over 70 percent of the Department's 12.7 million budget was generated from fees. Another 20 percent comes from the State's general tax fund in the form of yearly appropriations, with the remaining 10 percent coming from grants from the United States federal government. Organization Insurance Commissioner Deputy Insurance Commissioner Bail Bond Division - responsible for licensing and regulation of bail bondsmen Claims and Consumer Assistance Division - responsible for investigates all complaints lodged against insurance companies by the public Communications Division - responsible for providing public information and educational material Comptrollers Division - responsible for the internal fiscal affairs of the Department Information Technology Division - responsible for the internal information technology needs of the Department Financial Division - responsible for ensuring insurance companies meet all legal requirements and collects all premium taxes and fees Government Relations and Public Policy Division - responsible for maintain relations with the Oklahoma Legislature Human Resources Division - responsible for overseeing all internal personnel needs of the Department Investigation and Anti-Fraud Unit - responsible for investigating complaints against licensed insurance entities Legal Division - responsible for providing interla legal advice to the Department and prosecuting violations of the insurance laws Producers Licensing Division - responsible for licensing of resident and non-resident agents and adjusters to ensure they meet all legal requirements Rate and Form Filing Compliance Division - responsible for approving all life, accident, health, property, marine, vehicle and casualty insurance products to ensuring policies and rates are in compliance with the law Staffing

The Oklahoma Insurance Department, for fiscal year 2011, was authorized 135 full-time employees. See also Oklahoma Insurance Commissioner Governor of Oklahoma
41+255 40 42 43