The toad optic tectum as a recurrent on-center off-surround neural net with quenching threshold

The authors demonstrate that the toad optic tectum has memory and can implement a recurrent on-center off-sound neural net with quenching threshold. The main addition to previous tectal models is the quenching threshold, which is defined as a threshold that determines which features are transferred into memory. This implies that the memory is efferently organized, that is, that it stores prey and mate features. An alternative, afferently organized model would store all R2 and R3 input in separate memories and provide a selection mechanism to determine what information is transferred out of memory and is integrated to form efferent commands. The author´s model augments the quenching threshold mechanism by demonstrating that TP inhibition can rely on the differential sensitivity of R2 and R3 cells to suppress selectively certain features from memory. In this way, it can modulate the quality as well as the quantity of features stored in memory.<>