Permanent tactile sensory loss reduces neuronal activity in the amygdala and ventral hippocampus and alters anxiety-like behaviors

Abstract

Tactile information from the whiskers (vibrissae) travels through the somatosensory cortex to the entorhinal cortex and the hippocampus, influencing development and psychological well-being. The lack of whiskers affects cognitive functions, spatial memory, neuronal firing, spatial mapping, and neurogenesis in the dorsal hippocampus. Recent studies underline the importance of tactile experiences in emotional health, noting that while tactile stimuli modulate the dorsal hippocampus, the effects of tactile deprivation on anxiety-like behaviors and neural activity in regions like the ventral hippocampus and amygdala are less understood. This study aims to investigate the impact of permanent tactile deprivation on modifying anxiety-like behaviors and c-Fos expression (a marker of neuronal activity) in the dorsolateral and central nucleus of the amygdala and the ventral hippocampus, two regions involved in emotional memory and anxiety. We sectioned the infraorbital nerve, responsible for transmitting whisker information, in CD1 mice to examine how tactile deprivation modifies the behavioral activity in the Elevated Plus Maze and Open-Field Test. Our data revealed a reduction in anxiety-related behaviors post-deprivation, which was linked to a significant decrease in c-Fos expression in the barrel cortex, as well as ventral hippocampus (CA1, dentate gyrus) and dorsolateral, central nucleus of the amygdala, suggesting impaired processing in emotional-regulator brain regions. In conclusion, tactile inputs reduce neuronal activity regulators in brain regions related to emotional regulation, which may trigger possible failures in risk perception or self-protective behaviors associated with the lack of appropriate anxiety responses.