Depicting the inner and outer nose: The representation of the nose and the nasal mucosa on the human primary somatosensory cortex (SI)

Abstract

The nose is important not only for breathing, filtering air, and perceiving olfactory stimuli. Although the face and hands have been mapped, the representation of the internal and external surface of the nose on the primary somatosensory cortex (SI) is still poorly understood. To fill this gap functional magnetic resonance imaging (fMRI) was used to localize the nose and the nasal mucosa in the Brodman areas (BAs) 3b, 1, and 2 of the human postcentral gyrus (PG). Tactile stimulation during fMRI was applied via a customized pneumatically driven device to six stimulation sites: the alar wing of the nose, the lateral nasal mucosa, and the hand (serving as a reference area) on the left and right side of the body. Individual representations could be discriminated for the left and right hand, for the left nasal mucosa and left alar wing of the nose in BA 3b and BA 1 by comparing mean activation maxima and Euclidean distances. Right-sided nasal conditions and conditions in BA 2 could further be separated by different Euclidean distances. Regarding the alar wing of the nose, the results concurred with the classic sensory homunculus proposed by Penfield and colleagues. The nasal mucosa was not only determined an individual and bilateral representation, its position on the somatosensory cortex is also situated closer to the caudal end of the PG compared to that of the alar wing of the nose and the hand. As SI is commonly activated during the perception of odors, these findings underscore the importance of the knowledge of the representation of the nasal mucosa on the primary somatosensory cortex, especially for interpretation of results of functional imaging studies about the sense of smell.

Analysis of Intracerebral Activity during Reflex Locomotion Stimulation According to Vojta’s Principle

“…Electrical stimulation of the supplementary cortical area elicits complex movements, rhythmic movements of the limbs, and rotational movements [29,33,34]. The change in the activity of the secondary sensory cortex in BA 7 can be a reaction to the perception of pressure caused by reflex locomotion stimulation [35,36], though the area reacting to somatosensory stimuli is especially the primary sensory cortex (BAs 1, 2, and 3) [2][3][4][5][6][7]9,10,37,38]. This area further reacts to painful and non-painful stimuli, especially when the subject concentrates on the location or intensity of the stimuli [35,39,40].…”

“…closed eyes until 5 min after the stimulation demonstrated a statistically significant difference at the significance level p ≤ 0.05 in the sense of increased current density: in the alpha-1 band in the primary motor cortex, primary sensory cortex, and the cingulate cortex (BA 4,3,24); in the alpha-2 band in the premotor and supplementary motor area, primary motor cortex, primary sensory cortex, and the cingulate cortex (BA 6,4,3,24); in the beta-1 band in the premotor and supplementary motor area, primary motor cortex, and primary sensory cortex (BAs 6, 4, 3); in the beta-2 band in the premotor, supplementary motor area, and primary motor cortex (BAs 6, 4) (Figure 2). We did not observe any statistically significant difference in the frequency bands gamma, delta, and theta.…”

“…Detailed descriptions of these reactions to the tactile stimulus have been provided in several studies. In fMRI studies, the authors describe activation changes in the Brodmann area (BA) 3b and further in BAs 1 and 2 in the somatosensory stimulation in facial areas [2,3]. Fabri et al in 2005 [4] described the representation of the upper trunk part at the border between BAs 3a and 3b.…”

Can Swallowing Cerebral Neurophysiology Be Evaluated during Ecological Food Intake Conditions? A Systematic Literature Review

“…The transnasal canula sensation could be the cause of the parietal activity during the preparation phase, as suspected by the authors. Interestingly however, it was shown with MRI that tactile stimulation of the mucosa of the anterior nose elicit responses over the caudal part of the primary sensorimotor cortex, without parietal response [63]. To our knowledge, no study has tested the back of the nose/choanae cerebral sensory pattern.…”