Optogenetic study of networks in epilepsy
Epileptic seizures are characterized by transient bursts of pathological activity permeating brain networks. Since the middle of the 20th century, epilepsy researchers have used electrical and pharmacological tools to probe epileptic networks, leading to considerable improvements in treatments for epilepsy (Putnam and Merritt, 1937; Spiegel, 1937; Goddard et al., 1969; for excellent historical reviews of epilepsy drug development, see Shorvon, 2009a; Brodie, 2010). However, approximately 30% of patients with epilepsy do not respond to antiepileptic medications, and at this time we do not fully understand the conditions required for seizures to start, propagate, or stop. The recent development of optogenetics, because of its unprecedented precision, has revolutionized neuroscience, including epilepsy research; it has allowed us to target specific cell types and to switch them on or off with exquisite temporal control, revealing the details of seizure circuits like never before. Although the use of optogenetics in epilepsy research is still in its infancy, exciting work has already emerged, including new insights into the key roles of certain cell types in mediating seizures and epileptogenesis. Optogenetics has also revealed the potential of very specific targeted interventions that could allow on‐demand seizure interventions. Combining these new research tools with imaging technologies such as functional magnetic resonance imaging (fMRI) will allow us to have a better understanding of seizure circuits over the whole brain. This Review discusses some of the most recent breakthroughs in the field of optogenetics and epilepsy research. First, we discuss how optogenetics has been used to further our understanding of seizure circuits, and then we consider the future potential of this technique to aid both our understanding and the treatment of epilepsy.