1. A system for identifying keywords in search results comprising: a processor; a memory coupled to the processor; computer code loaded into the memory for executing on the processor, for implementing the following functionality: a plurality of neurons connected as a bidirectional neural network, the neurons being associated with words and documents, the neurons associated with words forming a first layer, and the neurons associated with documents forming a second layer, each neuron having multiple inputs from other neurons, a single output connecting the neuron to other neurons, and a threshold function at the single output, wherein at least some of the neurons of the first layer have connections between them and represent keywords in the documents; an activity regulator that regulates a fraction of a number of neurons of the neural network that are excited at any given time; and means for displaying to a user, on a display device, words of the search query and additional keywords from the documents and for identifying the neurons that correspond to keywords associated with at least one of the documents.