Visual and noxious electrical stimulus-evoked membrane-potential responses in anterior cingulate cortical neurons

Anterior cingulate cortex (ACC) is known to participate in numerous brain functions, such as memory storage, emotion, attention, as well as perception of acute and chronic pain. ACC-dependent brain functions often rely on ACC processing of various forms of environmental information. To understand the neural basis of ACC functions, previous studies have investigated ACC responses to environmental stimulation, particularly complex sensory stimuli as well as award and aversive stimuli, but this issue remains to be further clarified. Here, by performing whole-cell recording in vivo in anaesthetized adult rats, we examined membrane-potential (MP) responses of layer II/III ACC neurons that were evoked by a brief flash of visual stimulation and pain-related electrical stimulation delivered to hind paws. We found that ~54 and ~81 % ACC neurons exhibited excitatory MP responses, subthreshold or suprathreshold, to the visual stimulus and the electrical stimulus, respectively, with no cell showing inhibitory MP responses. We further found that the visually evoked ACC response could be greatly diminished by local lidocaine infusion in the visual thalamus, and only their temporal patterns but not amplitudes could be changed by large-scale visual cortical lesions. Our in vivo whole-cell recording data characterized in ACC neurons a visually evoked response, which was largely dependent on the visual thalamus but not visual cortex, as well as a noxious electrical stimulus-evoked response. These findings may provide potential mechanisms that are used for ACC functions on the basis of sensory information processing.