Scientists may have just found out why cannabis impairs memory and why endocannabinoids might help against epilepsy. Neuroscientists David Robbe and Gyorgy Buzsaki at Rutgers University and their colleagues recorded hippocampus activity in rats. Normally brain cells in this region often synchronize their electrical activity.

When the researchers injected rats with THC or a synthetic cannabinoid, they found the normally synchronized workings of the hippocampus became disrupted. While the cells did not change how often they fired nerve impulses, their timing became erratic. Imagine an orchestra where the musicians are deafened and perhaps blindfolded, Buzsaki said. Researchers assume that synchronized brain cell activity is crucial for memory formation and think that THC disrupts this synchronized activity.

The scientists suggest the way THC disrupts synchronized brain cell activity might help fight seizures. During seizures, brain activity becomes abnormally strong synchronized.

More at: http://www.livescience.com/humanbiology/061119_pot_memory.html

(Sources: LiveScience.com of 19 November 2006, Robbe D, Montgomery SM, Thome A, Rueda-Orozco PE, McNaughton BL, Buzsaki G. Cannabinoids reveal importance of spike timing coordination in hippocampal function. Nat Neurosci. 2006 Nov 19; [Electronic publication ahead of print])