Self-organization of shift-invariant receptive fields

✍ Scribed by Kunihiko Fukushima

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 345 KB
• Volume: 12
• Category: Article
• ISSN: 0893-6080
• DOI: 10.1016/s0893-6080(99)00039-8

✦ Synopsis

This paper proposes a new learning rule by which cells with shift-invariant receptive fields are self-organized. With this learning rule, cells similar to simple and complex cells in the primary visual cortex are generated in a network. To demonstrate the new learning rule, we simulate a three-layered network that consists of an input layer (or the retina), a layer of S-cells (or simple cells), and a layer of C-cells (or complex cells). During the learning, straight lines of various orientations sweep across the input layer. Here both S-and C-cells are created through competition. Although S-cells compete depending on their instantaneous outputs, C-cells compete depending on the traces (or temporal averages) of their outputs. For the self-organization of S-cells, only winner S-cells increase their input connections in a similar way to that for the neocognitron. In other words, the winner S-cells have LTP (long term potentiation) in their input connections. For the selforganization of C-cells, however, loser C-cells decrease their input connections (LTD long term depression), while winners increase their input connections (LTP). Here both S-and C-cells are accompanied by inhibitory cells. Modification of inhibitory connections together with excitatory connections is important for creation of C-cells as well as S-cells.