Better Olfactory Performance and Larger Olfactory Bulbs in a Mouse Model of Congenital Blindness

2020 ◽  
Vol 45 (7) ◽  
pp. 523-531
Author(s):  
Sara Touj ◽  
Samie Cloutier ◽  
Amel Jemâa ◽  
Mathieu Piché ◽  
Gilles Bronchti ◽  
...  
Keyword(s):  
Performance Test ◽  
Brain Plasticity ◽  
Olfactory Threshold ◽  
Olfactory Bulbs ◽  
Threshold Test ◽  
Anatomical Plasticity ◽  
Sensory Modalities ◽  
Olfactory Processing ◽  
Granular Layers ◽  
Early Blindness

Abstract It is well established that early blindness results in enhancement of the remaining nonvisual sensory modalities accompanied by functional and anatomical brain plasticity. While auditory and tactile functions have been largely investigated, the results regarding olfactory functions remained less explored and less consistent. In the present study, we investigated olfactory function in blind mice using 3 tests: the buried food test, the olfactory threshold test, and the olfactory performance test. The results indicated better performance of blind mice in the buried food test and odor performance test while there was no difference in the olfactory threshold test. Using histological measurements, we also investigated if there was anatomical plasticity in the olfactory bulbs (OB), the most salient site for olfactory processing. The results indicated a larger volume of the OB driven by larger glomerular and granular layers in blind mice compared with sighted mice. Structural plasticity in the OB may underlie the enhanced olfactory performance in blind mice.

scholarly journals Beat Detection Recruits the Visual Cortex in Early Blind Subjects

Life ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 296
Author(s):  
Rodrigo Araneda ◽  
Sandra Silva Moura ◽  
Laurence Dricot ◽  
Anne G. De Volder
Keyword(s):  
Brain Plasticity ◽  
Brain Activity ◽  
Sensory Modality ◽  
Brain Regions ◽  
Rhythm Perception ◽  
Brain Areas ◽  
Sensory Modalities ◽  
Beat Detection ◽  
The Brain ◽  
Early Blindness

Using functional magnetic resonance imaging, here we monitored the brain activity in 12 early blind subjects and 12 blindfolded control subjects, matched for age, gender and musical experience, during a beat detection task. Subjects were required to discriminate regular (“beat”) from irregular (“no beat”) rhythmic sequences composed of sounds or vibrotactile stimulations. In both sensory modalities, the brain activity differences between the two groups involved heteromodal brain regions including parietal and frontal cortical areas and occipital brain areas, that were recruited in the early blind group only. Accordingly, early blindness induced brain plasticity changes in the cerebral pathways involved in rhythm perception, with a participation of the visually deprived occipital brain areas whatever the sensory modality for input. We conclude that the visually deprived cortex switches its input modality from vision to audition and vibrotactile sense to perform this temporal processing task, supporting the concept of a metamodal, multisensory organization of this cortex.

scholarly journals The Independent Evolution of Dorsal Pallia in Multiple Vertebrate Lineages

2021 ◽  
pp. 1-12
Author(s):  
Georg F. Striedter ◽  
R. Glenn Northcutt
Keyword(s):  
Olfactory Bulbs ◽  
Sensory Inputs ◽  
Independent Evolution ◽  
Sensory Modalities ◽  
Olfactory Input ◽  
Cartilaginous Fishes

Comparative neurobiologists have long wondered when and how the dorsal pallium (e.g., mammalian neocortex) evolved. For the last 50 years, the most widely accepted answer has been that this structure was already present in the earliest vertebrates and, therefore, homologous between the major vertebrate lineages. One challenge for this hypothesis is that the olfactory bulbs project throughout most of the pallium in the most basal vertebrate lineages (notably lampreys, hagfishes, and lungfishes) but do not project to the putative dorsal pallia in teleosts, cartilaginous fishes, and amniotes (i.e., reptiles, birds, and mammals). To make sense of these data, one may hypothesize that a dorsal pallium existed in the earliest vertebrates and received extensive olfactory input, which was subsequently lost in several lineages. However, the dorsal pallium is notoriously difficult to delineate in many vertebrates, and its homology between the various lineages is often based on little more than its topology. Therefore, we suspect that dorsal pallia evolved independently in teleosts, cartilaginous fishes, and amniotes. We further hypothesize that the emergence of these dorsal pallia was accompanied by the phylogenetic restriction of olfactory projections to the pallium and the expansion of inputs from other sensory modalities. We do not deny that the earliest vertebrates may have possessed nonolfactory sensory inputs to some parts of the pallium, but such projections alone do not define a dorsal pallium.

Author response for "Structural brain plasticity induced by early blindness"

2020 ◽  
Author(s):  
Sara Touj ◽  
Daniel Gallino ◽  
M. Mallar Chakravarty ◽  
Gilles Bronchti ◽  
Mathieu Piché
Keyword(s):  
Brain Plasticity ◽  
Author Response ◽  
Early Blindness ◽  
Structural Brain

scholarly journals Olfactory processing and odor specificity: a meta-analysis of menstrual cycle variation in olfactory sensitivity

2014 ◽  
Vol 77 (3) ◽  
pp. 331-345 ◽  
Author(s):  
Lenka Martinec Nováková ◽  
Jan Havlíček ◽  
S. Craig Roberts
Keyword(s):  
Meta Analysis ◽  
Evolutionary Significance ◽  
Olfactory Sensitivity ◽  
Body Odor ◽  
Olfactory Threshold ◽  
Biologically Relevant ◽  
Odor Processing ◽  
Phenyl Ethyl Alcohol ◽  
Olfactory Processing ◽  
Cyclic Changes

Abstract Cycle-correlated variation in olfactory threshold, with women becoming more sensitive to odors mid-cycle, is somewhat supported by the literature but the evidence is not entirely consistent, with several studies finding no, or mixed, effects. It has been argued that cyclic shifts in olfactory threshold might be limited to odors relevant to the mating context. We aimed to test whether the evidence currently available points in the direction of odor-specific or, rather, general changes in olfactory sensitivity and, if the former is the case, to what group of odorants in particular. We carried out a meta-analysis of relevant studies which together used a variety of different odorants, including some found in food, body odor, and some that occur in neither of these. First we tested whether there appears to be an overall effect when all studies are included. Next, we hypothesised that if cyclic changes in olfactory processing are odor-specific and tuned to biologically relevant odors, we should find changes in detection thresholds only for odorants found in body odor, or for those that are perceptually similar to it. In contrast, if threshold patterns are linked to more general fluctuations in odor processing across the cycle, we would not expect changes in relation to any particular odorant group. The results support the view that there is significant cycle-correlated variation. Thresholds were in general significantly lower in the fertile than the non-fertile phases, with effect sizes consistently in this direction. This same conclusion applied to both ‘food’ and ‘musky’ odorants, despite their different evolutionary significance, and to the androgen steroids (androstadienone, androstenone, and androsterone), but could not be applied to phenyl-ethyl alcohol. The results indicate that olfactory sensitivity may be a non-adaptive by-product of the general physiological fluctuations or differences in neural processing experienced across the cycle to a broad spectrum of odorants, rather than being specifically selected for mate choice-related odors.

scholarly journals Olfaction in patients with Parkinson’s disease: a new threshold test analysis through turning points trajectories

2021 ◽  
Author(s):  
Maria Paola Cecchini ◽  
Elisa Mantovani ◽  
Angela Federico ◽  
Alice Zanini ◽  
Sarah Ottaviani ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Test Pattern ◽  
Turning Points ◽  
Motor Symptom ◽  
Olfactory Threshold ◽  
Test Analysis ◽  
Threshold Test ◽  
Additional Information ◽  
Olfactory Deficit

AbstractOlfactory deficit is a widely documented non-motor symptom in Parkinson’s disease (PD). Abnormal turning points trajectories through olfactory threshold testing have been recently reported in patients with olfactory dysfunction, who seem to adapt faster to olfactory stimuli, but data on PD patients are lacking. The aim of this study is to perform olfactory threshold test and explore the turning points trajectories in PD patients in comparison to normal controls. We recruited 59 PD patients without dementia, and no conditions that could influence evaluation of olfaction and cognition. Sixty healthy subjects served as controls. Patients and controls underwent a comprehensive olfactory evaluation with the Sniffin’ Sticks extended test assessing threshold, discrimination and identification and a full neuropsychological evaluation. Besides, threshold test data were analyzed examining all the turning points trajectories. PD patients showed a different olfactory threshold test pattern, i.e., faster olfactory adaptation, than controls with no effect of age. Normosmic PD patients showed different olfactory threshold test pattern, i.e., better threshold score, than normosmic controls. Visuospatial dysfunction was the only factor that significantly influenced this pattern. Olfactory threshold trajectories suggested a possible adaptation phenomenon in PD patients. Our data offered some new insights on normosmic PD patients, which appear to be a subset with a specific psychophysical profile. The analysis of the turning points trajectories, through an olfactory threshold test, could offer additional information on olfactory function in PD patients. Future larger studies should confirm these preliminary findings.

The Pyridine Scale for Clinical Measurement of Olfactory Threshold: A Quantitative Reevaluation

1979 ◽  
Vol 87 (6) ◽  
pp. 717-733 ◽  
Author(s):  
Allen H. Sherman ◽  
John E. Amoore ◽  
Vivian Weigel
Keyword(s):  
Normal Subjects ◽  
Clinical Applications ◽  
Olfactory Threshold ◽  
Detection Thresholds ◽  
Clinical Measurement ◽  
Threshold Test ◽  
Olfactory Detection ◽  
Olfactory Detection Thresholds ◽  
Precision And Accuracy ◽  
Existing Data

Serial dilutions of pyridine in water are employed for measuring the olfactory detection thresholds of patients. Experimental precautions are described that improve the precision and accuracy of the method. Existing data on the sensitivities of hyposmic patients are confirmed, but the sensitivities of normal subjects and of hyperosmic patients are believed to have been substantially overestimated in some earlier publications. Routine clinical applications of the revised pyridine odor threshold test are discussed. In the authors' experience, the average cystic fibrosis patient is slightly hyposmic, and some cases of pituitary tumor are accompanied by a 100,000-fold hyperosmia.

scholarly journals Nasal functional modifications after physical exercise: olfactory threshold and peak nasal inspiratory flow

2010 ◽  
Vol 48 (3) ◽  
pp. 277-280
Author(s):  
G. Marioni ◽  
G. Ottaviano ◽  
A. Staffieri ◽  
M. Zaccaria ◽  
V.J. Lund ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Inspiratory Flow ◽  
Nasal Patency ◽  
Olfactory Threshold ◽  
Threshold Test ◽  
Significant Difference ◽  
The Mean ◽  
The Stability ◽  
Peak Nasal Inspiratory Flow ◽  
Olfactory Thresholds

Statement of problem: The respiratory nasal effects of physical exercise have been extensively investigated; on the other hand there are no data regarding olfactory threshold modification after aerobic physical exercise. Methods: The present prospective study investigated the modifications in nasal respiratory flows and olfactory thresholds after controlled aerobic physical exercise in a cohort of 15 adult, healthy volunteers. The Peak Nasal Inspiratory Flow (PNIF), and the Sniffin’ Sticks olfactory threshold test were used for our determinations. Main results: The mean PNIF after physical exercise was significantly higher than the mean PNIF value found before physical exercise. Statistical analysis ruled out any significant difference between mean olfactory thresholds pre vs post physical exercise. Principal conclusions: These outcomes confirmed PNIF sensitivity and reliability also in determining the changes in nasal patency occurring after physical exercise. The active vasoconstriction of nasal mucosa associated with the reduction of blood flow to the olfactory epithelium due to physical exercise may be compensated for by the increase of olfactory molecules that reach the olfactory mucosa because of nasal mucosal shrinkage: this mechanism could explain the stability of mean olfactory threshold after physical exercise.

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