CFNetwork

CFNetwork
Click on the image for a live example

Continuous Firing Rate Networks CFNetwork have a series of nodes representing groups of neurons and connections between them. Node and connection types are added or modified with the controls on the right. Those that have been defined are available in the main window to be torn off and stuck together to construct networks.

The network is composed of a set of nodes and the synaptic connections between them. Nodes and connections may be of various types as defined by the lists and sliders on the lower right hand side. New types may be defined here, or with a separate editor from the main Catacomb window. All the currently defined types appear at the top of the drawing space. To construct a network, tear off nodes and connections as required and join the connections to the nodes with their "sticky" ends. To remove a connection, lift it off with the right mouse button.

Each node is drawn in two colors: the inner disk corresponds to its type, as in the top row, the outer disk is specific to this node. To change the color for all nodes of one type, select that type in the list editor on the middle right and then "set color" from the popup menu where the name of the node type appears. To set a node's individual color, highlight it by clicking in the diagram and select "set color" from where its name appears on the bottom left hand side.

New types of nodes and links can be created with the "new instance" option on the corresponding menus on the right hand side. Each node type has three parameters, the starting activity for nodes of that type, A_0, their decay timescale T_dec and threshold thresh.

Each link type has a weight and two possible actions: Vm-Esyn for links with a reversal potential, and absolute for those without. In the first case, the Esyn field gives the reversal potential. When absolute is selected, Esyn is ignored.

The value of Esyn is converted to a color between red (-60) and green (+60) for drawing the link. Each link type also has a color of its own which may be set from the menu under the "link type" button near the middle on the right. The weight of a connection is illustrated by the size of the blob touching the postsynaptic cell in the diagram.