A paper has recently been published that has everyone buzzing. A Texas group has found a mechanism for short-term memory (here).

There are types of memory - working memory, long-term memory and one or more intermediate memories. Until recently, it was thought that the working memory was in the form of circular networks of cells that could sustain activity in their circuits for short periods of time. This theory was problematic. The new research has shown that certain cells can maintain activity for a minute or more after a short stimulation. This is the sort of time frame that is needed for working memory. It has been compared to the RAM of a computer as opposed to the hard disk. The cells are where short-term memory is expected to reside – the prefrontal cortex.

In short-term memory tasks, individual prefrontal cortical (PFC) neurons can maintain persistent action potential output during delay periods between informative cues and behavioral responses. … Here we used patch-clamp recording of layer 5 PFC pyramidal neurons to identify a postsynaptic depolarization that was evoked by action potential bursts and mediated by metabotropic glutamate receptor 5 (mGluR5). This depolarization occurred in the absence of recurrent synaptic activity… We propose that burst-evoked intrinsic depolarization is a form of short-term cellular memory.

Working memory appears to be involved in the production of consciousness. The identification of these memory cells may soon clarify some aspects of awareness.