6. 1 Neutral Network As Stochastic Gradient system Classify Neutral network model by their synaptic connection topologies and by how learning modifies their connection topologies synaptic connection topologies feedforward: if no closed synaptic loops l2feedback: if closed synaptic loops or feedback pathways how learning modifies their connection topologies 1. Supervised learning: use class-membership information of' training samples 2.Unsupervised learning: use unlabelled training samplings 2003.11.192003.11.19 2 6.1 Neutral Network As Stochastic Gradient system Classify Neutral network model By their synaptic connection topologies and by how learning modifies their connection topologies 1. : 2. : feedforward if no closed synaptic loops feedback if closed synaptic loops or feedback pathways    1. : 2. : Supervised learning use class membership information of training samples Unsupervised learning use unlabelled training samplings  −     synaptic connection topologies how learning modifies their connection topologies