“…Acute brain preparations and slices are commonly used for in vitro study of mammalian brain functions (Ballanyi, 1999) and optical imaging (Cohen, 1988;Canepari and Zecevic, 2010). Water-soluble fluorescent ANEP-based VSDs, like di-1-ANEPPS (JPW3028), di-2-ANEPEQ (JPW1114) or di-4-ANEPPS, are often chosen for intracellular loading and bath-application in cortical slices (Grinvald et al, 1987;Antic et al, 1997;Foust et al, 2011;Palmer and Stuart, 2006;Sinha and Saggau, 1999;Tominaga et al, 2000). However, a series of lipophilic VSDs with significantly higher sensitivity to membrane potential changes has been synthesized .…”