Retina — this is not just a mediator between the environment and the brain, not just a set of photosensitive elements, which transmits the analysis center everything feels. Retina also deals with some "creative work": it analyzes the intensity of light, its direction, determines where the edge of the picture. For information about these options, you want to encrypt, "digitize", translated into nerve impulses and sent along the optic nerve.
|Layer of bipolar cells in the retina (photo revoelkel).|
For a long time it was thought that such coding abilities has only one type of cells — the retinal ganglion cells. That is, only that they can form a complex signal, convert information from one language to another. The rest seemed to be working on "analog mechanism." But, as the experience of researchers from the University of Tübingen (Germany), in the retina of mammals possess property encode information than ganglion cells, also bipolar.
|Analog signal common bipolar cell (green) and the signal "digitize" the bipolar cells (red) (Figure Tom Baden / University of Tubingen).|
Bipolar cells act as intermediaries, they connect the photoreceptors — rods and cones — with ganglion cells. The researchers recorded signals in the synapses of bipolar cells of mice in response to a visual stimulus. The cells were distributed into eight classes (which is also supported by anatomical and physiological observations). However, a class of cell response to the stimulus was very different from the others. These cells reacted quickest, their reactions were similar to each other, and the signal that they sent, was formed on the principle of "all or nothing". The other signal is bipolar cells corresponded to the level of irritation.
Such reactions have been observed, but until now it was considered a rare exception. This time, scientists were able to prove that this is not something out of the ordinary, and the normal way to work some bipolar cells. Clearly, the role of the retina in the perception of visual information should be slightly revised because it does more pre-analytical work than we thought.
The article with the research published in the journal Current Biology.
Prepared according to the University of Tübingen.