Spatio-temporal response of LGN on-center type cell.

<p>The response was mapped with the reverse correlation algorithm, using either non-biphasic retinal inputs (A–C,E) or biphasic retinal inputs (D). (A) Spatio-temporal response of an on-center type cell in model LGN. Responses were obtained by cross-correlating stimulus and response at the time intervals given below the figures. Red: response to bright stimulus at that location, blue: response to dark stimulus at that location. Note the change in sign after 50 milliseconds. Similar results were obtained for other LGN on-center type units. (B) Spatio-temporal response profile of on-center type cells in cat LGN obtained with the reverse correlation algorithm <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000373#pcbi.1000373-Alonso1" target="_blank">[1]</a>. (C) The removal of feedback in the model causes the previously biphasic responses to disappear. (D) Temporal response profile of on-center type cell in a model with biphasic retinal inputs. Model activity is normalized by the initial response magnitudes. The biphasic response in LGN is more pronounced in the presence of predictive feedback compared to a situation in which the LGN response is fully determined by biphasic retinal input (for comparison, see e.g. <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000373#pcbi.1000373-Usrey1" target="_blank">[21]</a>). (E) Average model LGN and V1 representations after reference stimuli consisting of bright stimulus regions have been presented. Black depicts off regions, white depicts on regions. When V1 predictions of the bright reference stimulus arrive in model LGN, they are compared against a new and unexpected stimulus representation. The difference between the predicted bright region and the second stimulus is negative, exciting LGN off-center type cells.