Extrastriate cortex

Extrastriate Cortex

The extrastriate cortex is a region of the cerebral cortex located in the occipital lobe of the brain, adjacent to the primary visual cortex (V1). It is involved in the processing of visual information and is crucial for the perception of complex visual stimuli. The extrastriate cortex includes several distinct areas, each with specialized functions in visual processing.

Brodmann areas 17, 18, and 19, which include the extrastriate cortex

Anatomy

The extrastriate cortex encompasses several Brodmann areas, primarily areas 18 and 19, which are located around the primary visual cortex (Brodmann area 17). These areas are part of the visual cortex and are involved in higher-order visual processing. The extrastriate cortex is divided into multiple regions, each responsible for different aspects of visual perception, such as motion, color, and form.

Brodmann Area 18

Brodmann area 18, also known as the secondary visual cortex or V2, is located adjacent to the primary visual cortex. It receives input from V1 and is involved in the processing of visual information related to orientation, spatial frequency, and color. V2 is organized into stripes, each of which processes different types of visual information.

Brodmann Area 19

Brodmann area 19, also known as the tertiary visual cortex or V3, is involved in the processing of complex visual stimuli, such as motion and depth perception. It receives input from both V1 and V2 and is connected to other visual areas in the brain, including the dorsal stream and ventral stream.

Function

The extrastriate cortex plays a critical role in the interpretation and integration of visual information. It is involved in the perception of motion, depth, color, and form. The extrastriate cortex is also important for visual attention and the recognition of objects and faces.

Visual Processing Streams

The extrastriate cortex is part of two major visual processing streams:

• The dorsal stream, also known as the "where" pathway, is involved in the processing of spatial location and motion. It extends from the extrastriate cortex to the parietal lobe.
• The ventral stream, also known as the "what" pathway, is involved in the recognition and identification of objects. It extends from the extrastriate cortex to the temporal lobe.

Clinical Significance

Damage to the extrastriate cortex can result in various visual disorders, depending on the specific area affected. For example, lesions in V2 can lead to deficits in color perception, while damage to V3 can impair motion perception. Disorders such as visual agnosia and prosopagnosia are associated with dysfunction in the extrastriate cortex.

Related Pages

• Primary visual cortex
• Visual cortex
• Dorsal stream
• Ventral stream
• Brodmann area