User:Midd Intro Neuro/sandbox

Kim Cronise

Link: Middlebury College

Link Wikipage: Middlebury College

Introduction:

We are learning about Wickipedia.

Methods:

This is hard.

Results:

Epic Fail

Conclusions:

This is still hard.

Receiving Information

The light energy that comes from the rays bouncing off of an object is converted into chemical energy by the cells in the retina of the eye. This chemical energy is then converted into action potentials that are transferred through the optic nerve and across the optic chiasm, where it is first processed by the lateral geniculate nucleus of the thalamus. From there the information is sent to the primary visual cortex, region V1. It then travels from the visual areas in the occipital lobe to the parietal and temporal lobes via two distinct anatomical streams. These two cortical visual systems were classified by Ungerleider and Mishkin (1982, see two-streams hypothesis) . One stream travels ventrally to the inferior temporal cortex (from V1 to V2 then through V4 to ITC) while the other travels dorsally to the posterior parietal cortex. They are labeled the “what” and “where” streams , respectively. The Inferior Temporal Cortex receives information from the ventral stream, understandably so, as it is known to be a region essential in recognizing patterns, faces, and objects.

The dorsal stream (green) and ventral stream (purple) originating in the primary visual cortex.

How it Works

The information for color and form comes from P-cells that receive their information mainly from cones, so they are sensitive to differences in form and color, as opposed to the M-cells that receive information about motion mainly from rods. The neurons in the inferior temporal cortex, also called the inferior temporal visual association cortex, process this information from the P-cells. The neurons in the ITC have several unique properties that offer an explanation as to why this area is essential in recognizing patterns. They only respond to visual stimuli and their receptive fields always include the fovea, which is one of the densest areas of the retina and is responsible for acute central vision. These receptive fields tend to be larger than those in the striate cortex and often extend across the midline to unite the two visual half fields for the first time. IT neurons are selective for shape and/or color of stimulus and are usually more responsive to complex shapes as opposed to simple ones. A small percentage of them are selective for specific parts of the face. Faces and likely other complex shapes are seemingly coded by a sequence of activity across a group of cells, and IT cells can display both short or long term memory for visual stimuli based on experience.