Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensit

[osisposis]

.Assessment of cerebral blood flow in patients with multiple chemical sensitivity using near-infrared spectroscopy--recovery after olfactory stimulation: a case-control study

These results suggest that a past strong exposure to hazardous chemicals activates the PFC during olfactory stimuli in patients with MCS, and a strong activation in the OFC remains after the stimuli.

http://www.ncbi.nlm.nih.gov/pubmed/25682122
full
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4434236/




Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity

Multiple chemical sensitivity (MCS) patients usually react to odour compounds and the majority of neuroimaging studies assessed, especially at the cortical level, many olfactory-related correlates. The purpose of the present study was to depict sub-cortical metabolic changes during a neutral (NC) and pure (OC) olfactory stimulation by using a recently validated (18)F-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computer tomography procedure in 26 MCS and 11 healthy (HC) resting subjects undergoing a battery of clinical tests. Twelve subcortical volumes of interest were identified by the automated anatomical labeling library and normalized to thalamus FDG uptake. In both groups, when comparing OC to NC, the within-subjects ANOVA demonstrated a relative decreased metabolism in bilateral putamen and hippocampus and a relative increased metabolism in bilateral amygdala, olfactory cortex (OLF), caudate and pallidum. The between-groups ANOVA demonstrated in MCS a significant higher metabolism in bilateral OLF during NC. As in HC subjects negative correlations were found in OC between FDG uptake in bilateral amygdala and hippocampus and odor pleasantness scale, the latter positively correlated with MCS subjects' bilateral putamen FDG uptake in OC. Besides FDG uptake resemblances in both groups were found, for the first time a relative higher metabolism increase in OLF in MCS subjects at rest with respect to HC was found. When merging this aspect to the different subcortical FDG uptake correlations patterns in the two groups, the present study demonstrated to describe a peculiar metabolic index of behavioral and neurological aspects of MCS complaints.
http://www.ncbi.nlm.nih.gov/pubmed/26438099


Cortical activity during olfactory stimulation in multiple chemical sensitivity: a (18)F-FDG PET/CT study.
The results of our study suggest that cortical activity in subjects with MCS differs from that in healthy individuals during olfactory stimulation.
http://www.ncbi.nlm.nih.gov/pubmed/25690545


Brain responses to odor mixtures with sub-threshold components.
An odor presented within a mixture of odors can influence activation of brain regions such as the cingulate and the insula, even if subjects are not able to distinguish the mixture with and without the odor. This appears to be true even for subjects for which the odor, presented on its own, is too weak to be perceived. On the practical side these results suggest that the addition of a certain compound to a mixture of odors may not be detected on a cognitive level; however, this additional odor may significantly change the cerebral processing of this mixture.

http://www.ncbi.nlm.nih.gov/pubmed/24167499

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807048/

 

[osisposis]

so many articles on MCS just say MCS'ers react to tiny amounts of harmless stimuli that does not bother the general population that it's so very important to understand that first it takes a higher dose and/or chronic exposure to make you than sensitive to small amounts, chronic is a key word that incorporates both lower dose long term exposures and higher dose short term exposures, it just drives me crazy when this isn't addressed properly in research.

so very important to understand!

Assessment of cerebral blood flow in patients with multiple chemical sensitivity using near-infrared spectroscopy—recovery after olfactory stimulation: a case–control study

The symptoms of MCS can be mild to disabling, and they are triggered by multiple chemicals. These symptoms are reactions to previous chemical exposure that recur on subsequent exposure to the same or structurally unrelated chemicals at levels below those established as having harmful effects in the general population [2]. Central nervous system (CNS) symptoms such as headaches, dizziness, extreme fatigue, and concentration difficulties are common; airway and gastro-intestinal tract symptoms are also frequently reported [2, 10–12]. Diagnosis of MCS can be difficult because of the inability to assess the causal relation between exposure and symptoms [3, 13].

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4434236/