View source for Node (in neurocognitive linguistics)

'''Node''' in [[neurocognitive linguistics]] has two senses, both of which are defined in this article:

* ''Node'' as used in [[compact relational network notation]].
* ''Node'' as used in [[narrow relational network notation]].

=== In Compact Notation ===

A '''node''' is any point at which [[line|lines]] meet.  At each such point in [[relational network theory|relational network]] modeling, the type of node must be identified.
Nodes used in this form of relational network notation differ from one another according to three dimensions of contrast:

* ''Upward'' vs. ''downward'' orientation.  Downward is toward expression.  Upward is toward meaning or function.  For example, a lexicogrammatical node might point upward toward the sememic stratum or downward toward the phonological.
* ''[[AND node|AND]] vs. [[OR node|OR]].
* ''Ordered'' vs. ''unordered''.

Node types are also distinguished from one another on the basis of how they treat incoming activation.

Each node has a ''singular'' side to which one line is connected, and a ''plural side'' to which two or more lines connect.  With a few exceptions, nodes in compact notation are bidirectional, capable of carrying activation in either direction.

Another type of node is the [[tactic connector]], also known as a ''diamond node''.

=== In Narrow Notation ===

A '''node''' in narrow notation is part of an account of the internal structure of a node of compact notation.  The one-way nodes in narrow notation are of two types:

* The ''branching'' node, in which activation branches out from the singular side to the plural side.
* The ''junction'' node, in which activation comes from one or more lines on the plural side and may continue on the singular side.

The AND/OR difference is represented in narrow notation as a difference in threshold.  (Cf. [[threshold node]].)  Narrow notation has no distinction between ordered and unordered nodes; an account of ordering is provided by combinations of narrow elements, including additional ones, like [[inhibitory connection|inhibitory connections]].

=== Sources ===

*[[Sydney M. Lamb|Lamb, Sydney M.]]. 1999. ''[http://www.benjamins.com/cgi-bin/t_bookview.cgi?bookid=CILT%20170 Pathways of the Brain: The Neurocognitive Basis of Language].''  Philadelphia: John Benjamins.


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