Visual Cortex - V2

V2

Visual area V2, also called prestriate cortex, is the second major area in the visual cortex, and the first region within the visual association area. It receives strong feedforward connections from V1 (direct and via the pulvinar) and sends strong connections to V3, V4, and V5. It also sends strong feedback connections to V1.

Anatomically, V2 is split into four quadrants, a dorsal and ventral representation in the left and the right hemispheres. Together these four regions provide a complete map of the visual world. Functionally, V2 has many properties in common with V1. Cells are tuned to simple properties such as orientation, spatial frequency, and color. The responses of many V2 neurons are also modulated by more complex properties, such as the orientation of illusory contours, binocular disparity, and whether the stimulus is part of the figure or the ground (Qiu and von der Heydt, 2005). Recent research has shown that V2 cells show a small amount of attentional modulation (more than V1, less than V4), are tuned for moderately complex patterns, and may be driven by multiple orientations at different subregions within a single receptive field.

It is argued that the entire ventral visual-to-hippocampal stream is important for visual memory. This theory, unlike the dominant one, predicts that object-recognition memory (ORM) alterations could result from the manipulation in V2, an area that is highly interconnected within the ventral stream of visual cortices. In the monkey brain, this area receives strong feedforward connections from the primary visual cortex (V1) and sends strong projections to other secondary visual cortices (V3, V4, and V5). Most of the neurons of this area are tuned to simple visual characteristics such as orientation, spatial frequency, size, color, and shape. V2 cells also respond to various complex shape characteristics, such as the orientation of illusory contours and whether the stimulus is part of the figure or the ground. Anatomical studies implicate layer 3 of area V2 in visual-information processing. In contrast to layer 3, layer 6 of the visual cortex is composed of many types of neurons, and their response to visual stimuli is more complex.

In a recent study, the Layer 6 cells of the V2 cortex were found to play a very important role in the storage of Object Recognition Memory as well as the conversion of short-term object memories into long-term memories.