The gene, Activity-regulated cytoskeletal protein or Arc is known for its role in the storage of long term memories. Arc was first identified as having this role when mice with the gene knocked out displayed totally normal short term memory but had close to zero long term memory. The gene activates when promoted to do so from a handful of singling proteins which are activated by a handful of neurotransmitters, and when activated, in a single statement, Arc simply creates dendrite projections fairly quickly after being stimulated (within a hour). The expression of Arc happens in waves, the first which happens within the hour of the stimulation, the second follows a few hours later, and the third sometime after. The reason for expression in waves in not completely understood but it is believed the initial waves are preparatory activity, like most things biological, which creates feedback loops activating more genes which eventually allow for proper expression of the gene.
While Arc is not known to have any direct roles in disease, in Arc knock mice are known to be highly prone to seizures. I wrote about this article because as someone who experienced seizures for many years of my life I found it interesting. Pentobarbital is a drug I was put on for a short while which caused my seizures to get worse, this drug works deregulating singles across the entire brain. While, it is stated working on the whole brain equally, its use as a sleep aid and to treat people with traumatic injury, one could assume it works particularity heavily on the hippocampus. Arc, in order to work, need a ton of different singling molecules and so one would assume the function of the gene (with all its feedback loops) would probably be affected by Pentobarbital. This would explain why a fairly large number of patients who take Pentobarbital also experience an increased number of seizures, as it is also known a lack of expression of Arc causes seizures. Pentobarbital is no longer prescribed as a primary treatment to seizures (usually other things are tried first) but I would be interested in knowing if Arc is the reason why increased seizures are experienced.
If you would like to read the journal article it can be found here, and please don't stop taking your medicine, I am not a healthcare professional and this is not medical advise.