Differential Spatial Representation of Taste Modalities in the Rat Gustatory Cortex

Abstract

Discrimination between foods is crucial for the nutrition and survival of animals. Remarkable progress has been made through molecular and genetic manipulations in the understanding of the coding of taste at the receptor level. However, much less is known about the cortical processing of taste sensation and the organizing principles of the gustatory cortex (GC). Using genetic tracing, it has recently been shown that sweet and bitter taste are processed through segregated neuronal circuitries along the gustatory pathway up to the cortical level. This is in disagreement with the evidence that GC neurons recorded in both anesthetized and behaving animals responded to multiple taste modalities (including sweet and bitter). To investigate the functional architecture of the GC in regard to taste modalities, we used in vivo intrinsic optical imaging, a technique that has been successfully applied to explore the organization of other neocortical regions. We found that four of the primary taste modalities (sweet, bitter, salty, and sour) are represented by distinctive spatial patterns but that no region was specific to a single modality. In addition, we found that two tastants of similar hedonic value (pleasant or unpleasant) activated areas with more common regions than two tastants with opposite hedonic value. In summary, we propose that these specific cortical patterns can be used to discriminate among various tastants.

Neural mechanisms of nociception during orthodontic treatment

“…These anatomical findings indicate that the area corresponds to the secondary somatosensory cortex (S2) and oral region of the IC (IOR), as reported by Nakamura et al (49). S2/IOR receives varied somatosensory information from oral regions, including PDL sensation, gustation (50)(51)(52), and nociception (49,53,54). Interestingly, electrical stimulation of S2/IOR induces rhythmic jaw movement (55,56).…”

Familiar taste induces higher dendritic levels of activity-regulated cytoskeleton-associated protein in the insular cortex than a novel one

“…Early studies using neuroanatomical and electrophysiological techniques identified the dysgranular region of the IC as the gustatory cortex (Kosar et al 1986a,b). Also, in vivo intrinsic imaging experiments showed that the anterior part of the IC responded best to taste modalities (Accolla et al 2007). Further, a more recent study using neuronal activity mapping with Arc mRNA (Saddoris et al 2009) indicates that the integration of taste-related information mostly occurs in the anterior dysgranular region of the IC.…”

Internal body state influences topographical plasticity of sensory representations in the rat gustatory cortex

“…2A Left) and we conducted in vivo intrinsic optical imaging to map functional activity in the GC (Fig. 2 A Right) (13). Rats of CTA (n ϭ 8), CS-Ctrl (n ϭ 8), and US-Ctrl (n ϭ 5) groups were imaged on test day 2 (however, similar results were also obtained on TD1, n ϭ 4, data not shown) when there was a significant difference of the saccharin preference among the groups (Fig.…”

“…The GC therefore constitutes an ideal region to investigate sensory maps plasticity after conditioned learning. Recently, we studied the spatial representation of taste modalities in the GC (13). Taste maps differ across modalities and seem to contain also information about the pleasantness (or hedonic value) of the stimulus.…”