847
Expression of the inhibitory halorhodopsin NpHR in hippocampal principal cells has been recently used as a tool to effectively control chemically and electrically induced epileptiform activity in slice preparations , and to reduce in vivo spiking induced by tetanus toxin injection in the motor cortex .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None