Taste representation in the human insula

Abstract

The sense of taste exists so that organisms can detect potential nutrients and toxins. Despite the fact that this ability is of critical importance to all species there appear to be significant interspecies differences in gustatory organization. For example, monkeys and humans lack a pontine taste relay, which is a critical relay underlying taste and feeding behavior in rodents. In addition, and of particular relevance to this special issue, the primary taste cortex appears to be located further caudally in the insular cortex in humans compared to in monkeys. The primary aim of this paper is to review the evidence that supports this possibility. It is also suggested that one parsimonious explanation for this apparent interspecies differences is that if, as Craig suggests, the far anterior insular cortex is newly evolved and unique to humans, then the human taste cortex may only appear to be located further caudally because it is no longer the anterior-most section of insular cortex. In addition to discussing the location of taste representation in human insular cortex, evidence is presented to support the possibility that this region is better conceptualized as an integrated oral sensory region that plays role in feeding behavior, rather than as unimodal sensory cortex.

Introducing a Virtual Lesion Model of Dysphagia Resulting from Pharyngeal Sensory Impairment

“…Using fMRI, Lowell et al were also able to show that oral air pulse stimulation activates both motor and sensory components of the swallowing system, indicating their close functional connectivity, because swallowing is a motor task triggered by a sensory oropharyngeal stimulus to evoke the swallowing reflex [27]. Similar to our findings, they observed additional activation in the insula, which constitutes a primary gustatory cortex but is also known to integrate taste with other oral sensory modalities [28]. Moreover, they found activation in further areas such as the cingulate cortex, parietal operculum and subcortical structures like putamen and thalamus, which cannot reliably be localized with MEG [27].…”

“…Stimulation episodes contaminated by swallows were rejected. By applying a fourth order two-pass Butterworth filter prior to further computations, MEG data were filtered within five different frequency bands: theta (4-8 Hz), alpha (8-13 Hz), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), low gamma (30-60 Hz), and high-gamma (60-80 Hz).…”

Nicotine Alters Food–Cue Reactivity via Networks Extending From the Hypothalamus

“…Second, the caloric intake was followed by reduced functional coupling with a more superior network that primarily involved interoceptive regions. The insula and the operculum are well known to contain the primary gustatory area representing sensations of taste (Augustine, 1996;Small, 2010;Small et al, 1999) and both regions are responsive to pictures of palatable food (Simmons et al, 2005). In addition, the effect in the cingulate gyrus may be due to strong connections with insular regions potentially subserving evaluative functions to select and prepare for future actions (Medford and Critchley, 2010).…”

How the Brain Wants What the Body Needs: The Neural Basis of Positive Alliesthesia

“…In rodent models, inactivation of interoceptive regions of the insula has been demonstrated to disrupt nicotine self-administration (Forget et al, 2010), and in humans, lesions of the insula are associated with the dramatic cessation of cigarette craving and the disruption of smoking addiction (Naqvi et al, 2007). The insula also has significant anatomical connectivity to the ventral striatum (Fudge et al, 2005), and this may explain its involvement in the hedonic component of taste perception (Small, 2010). This evidence suggests a strong link between the activity of the interoceptive insula, the subjective experience of craving, and the hedonic processing of sensory stimuli.…”