Biological Psychology

This article picks up where the last one left off. The dark current with the cell 'on' and inhibits the next cell in the transduction process. For example, if you are seeing a bush the rods and cones respond and once they respond they are disabled and you have a stabilized image. There is nothing there but rods and cones that do not respond that does not normally happen. The eyes continuously move focus. There is a reason for this and it is physiological nystagmus where tiny, tiny movements to new rods and cones. The brain has to track the movement of the eyes and subtract that from any other movement. The percept is a construct of what you think you see and which is built up in your head may not be true.

In a diagram that I drew that is suppose to be the retina there are 6.5 million cones and 120 million rods. The rods are on the top of the retina and the cones are in a small area at the bottom. Then there are the ganglion cells as well as the bi-polar cells that along with optic nerve and 1 million axons where some axons have a few cones. Axons carry many, many rods according to Hartline researcher I learned from this lecture: a fragment from this is that some axons respond to intensity of light while others are silent and don't do anything but only respond to small dark moving objects with velocity and the angle of light. The retina and brain tissue 'forward brain' with others responded to stable transitions between light and dark (shadow) receptor fields in the retina and computations being made by the bi-polar cells.

Also, this is where a piece of data that goes into the ganglia cells and analysis occurs in the retina and reports from this area if I remember right. It also includes from the temporal hemisphere and the thalamus and even the nasal hemisphere and the thalamus. The nasal information is contralateral to the brain ipsilateral is temporal and the optical chiasm. The rods and cones detect specific wavelength of light activity. The activity receptor fields processes to the brain from the retina. Transduction occurs and analyzes to the optic nerve. The optic chiasm goes into sorting to the cortex and allows the sharpening of information to the way to the thalamus which will be more clarified by the thalamus.

At the cortex there are thin, large columns of cells with particular functions. There are six layers sending information out or receiving or even going back and forth. There is an area known as the Vision-occipital cortex with the primary visual cortex and is where the first cortical processing starts. This structural device that is going on in receptor fields will break information into 25,000 pieces or units represented in the cortex. One piece of information taps in a column of cells that are responsible for color (hue) at that point. Information at both sides of eye are contralateral and ipsilateral sides. This brings us to shape orientation of edges and computational is also picked up starting now. There are nerve tracks to and back always a continuing process for primary and secondary analysis. There are 40 areas in the brain that receive information from the eyes and sent forward or gets sent back for re-entering processing for increasing specialization; texture and shape of image being analyzed in the lateral central fissure.

This is the end of the Vision articles and the next article is gong to be about the parts of the brain and some issues that affect it.

(Please remember that these articles are from lecture notes.)