2004/01/01 by Toru Ishizuka, Masaaki Kakuda, Rikita Araki +2 · 4 citations
Arts and Humanities · Neuroscience · #Historical Linguistics and Language Studies #Lexicography and Language Studies #Neural dynamics and brain function #Neuroscience and Neuropharmacology Research #Photoreceptor and optogenetics research #linguistics and terminology studies
paper · doi:10.1016/j.neures.2005.10.009
openalex publication_date 2004/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/23
Neurons become photosensitive by genetically introducing one of green algae-derived protein, channelrhodopsin-2 (ChR2). Here, we quantitatively investigated the rapidness of the light-gated current of ChR2 expressed in PC12 cells using blue light-emitting diode (LED) light. The light-gated current consists of two components, inactivating and non-inactivating. The magnitude of inactivating component was almost linearly related to the light intensity. The non-inactivating component showed a tendency to saturate at high illumination. Both the activation and inactivation rates of the light-gated current were linearly dependent on the light intensity. However, the activation rate (turning-on rate) is about 10-fold faster than the inactivation rate. Although the turning-off time constant was little dependent on the light intensity, that at the end of 1s light pulse was about two-fold larger than that at 20 ms. Neurons are also made photosensitive by the expression of ChR2 in the living animal. Since both the turning-on and turning-off time constants of light-gated current was smaller than the membrane time constant of neurons, the LED light illumination of the photosensitive neurons was enough to evoke action potentials in a pulse-to-pulse manner in an acute slice of hippocampus.