Optical imaging of spatiotemporal patterns of glutamatergic excitation and GABAergic inhibition in the guinea‐pig auditory cortex in vivo.

Imaging synaptic inhibition in transgenic mice expressing the chloride indicator, Clomeleon

“…However, the signals employed by these methods mainly rely on neuronal excitation. Apart from a few reports of successful imaging of inhibitory circuit activity though the use of voltage-sensitive dyes (Horikawa et al, 1996;Cohen and Yarom, 2000;Derdikman et al, 2003), autofluorescence (Ebner et al, 2005), pH indicators (Elias et al, 1993) and organic Cl − indicator dyes (Isomura et al, 2003), synaptic inhibition has largely remained invisible even though inhibition contributes fundamentally to neuronal computation.…”

Optical imaging of plastic changes induced by fear conditioning in the auditory cortex

“…It has been reported that optical imaging may record neuronal responses mainly from layers II and III in the cerebral cortex (Horikawa et al 1996;Lippert et al 2006), implying that synaptic plasticity may have been induced in these layers of the auditory cortex in the present study. These results correspond to reports that layers II and III of the barrel cortex play an important role in cortical plastic changes (Huang et al 1998) and that LTP can be induced in the horizontal connections in layers II and III of the motor cortex (Hess et al 1996).…”

“…The area enlargement for the CS sound after the normal conditioning suggests that the activity affected neighboring regions, adjacent to the core area of the CS sound, which were not activated before the conditioning. It has been reported that the excitatory postsynaptic potential (EPSP) on the dendrites is involved in the optical response from the cortex observed by in vivo optical imaging with voltage sensitive dye (Grinvald et al 1994;Horikawa et al 1996). It is conceivable that fear conditioning promoted the efficiency of synaptic transmission in the core and/or border area of the CS sound.…”

“…Pharmacological experimental data in vivo have shown that responses for acoustic stimuli recorded by optical imaging consist of the following three main components: (1) non-NMDA (N-methyl-D-aspartate) glutamate receptor dependent excitatory postsynaptic potential (EPSP), which is a fast response component (2) NMDA glutamate receptor dependent EPSP, which is a slow response component and (3) GABA (c-amino butyric acid) receptor dependent inhibitory postsynaptic potential (IPSP) (Horikawa et al 1996). Furthermore, it has been reported that neural circuits involving the medial geniculate body, the amygdale, the basal forebrain and the auditory cortex are very important for fear conditioning using sound and foot-shock, and that plastic changes in the auditory cortex are induced by the release of acetylcholine (ACh) from the basal forebrain to cortex during conditioning (Weinberger and Bakin 1998;Edeline 1999).…”

“…The above hypothesis is based on this evidence. To further substantiate this hypothesis, we employed the optical imaging method with a voltage sensitive dye (Cohen et al 1978;Grinvald et al 1988;Horikawa et al 1996Horikawa et al , 2001). The optical imaging method has recently attracted attention as one of the useful methods for investigating the dynamic function of the brain.…”