Biomedical subjects

Jane Plailly

Publications and source records attributed to Jane Plailly.

6 recordsLinked to original sources

PubMed2007

Involvement of the left anterior insula and frontopolar gyrus in odor discrimination.

Discriminating between successively presented odors requires brief storage of the first odor's perceptual trace, which then needs to be subsequently compared to the second odor in the pair. This study explores the cortical areas involved in odor discrimination and compares them with findings from studies of working-memory, traditionally investigated with n-back paradigms. Sixteen right-handed subjects underwent H(2) (15)O positron emission tomography during counterbalanced conditions of odorless sniffing, repeated single odor detection, multiple odor detection, and conscious successive discrimination between odor pairs. Eight odorants were delivered using a computer-controlled olfactometer through a birhinal nasal cannula. Conscious successive odor discrimination evoked significantly greater activity in the left anterior insula and frontopolar gyrus when compared to reported sensory detection of the identical odors. Additional activation was found in the left lateral orbital/inferior frontal and middle frontal gyri when discrimination was compared to the odorless condition. The left anterior insula is likely involved in the evaluation of odor properties. Consistent with other studies, frontopolar and middle frontal gyrus activation is more likely related to working memory during odor discrimination.

Adult↗

PubMed2005

Left temporo-limbic and orbital dysfunction in schizophrenia during odor familiarity and hedonicity judgments.

Impairments of olfactory processing in patients with schizophrenia (SZ) have been reported in various olfactory tasks such as detection, discrimination, recognition memory, identification, and naming. The purpose of our study was to determine whether impairments in odor familiarity and hedonicity judgments observed in SZ patients during a previous behavioral study are associated with modifications of the activation patterns in olfactory areas. Twelve SZ patients, and 12 healthy comparison (HC) subjects, were tested using the H2(15)O-PET technique and 48 different odorants delivered during 8 scans. In addition to an odorless baseline condition, they had either to detect odor, or to judge odor familiarity or hedonicity, giving their responses by pressing a button. Regional cerebral blood flows during olfactory conditions were compared with those for baseline condition. Between-group analyses were then performed, and completed by regions of interest analyses. Both groups had equivalent ability for the detection of suprathreshold odorants, but patients found odors less familiar, and pleasant odors less pleasant than HC subjects. These behavioral results were related to functional abnormalities in temporo-limbic and orbital olfactory regions lateralized in the left hemisphere: the posterior part of the piriform cortex and orbital regions for familiarity judgments, the insular gyrus for hedonicity judgments, and the left inferior frontal gyrus and anterior piriform cortex/putamen region for the three olfactory tasks. They mainly resulted from a lack of activation during task conditions in the SZ patients. These data could explain olfactory disturbances and other clinical features of schizophrenia such as anhedonia.

Adult↗

PubMed2004

Involvement of right piriform cortex in olfactory familiarity judgments.

Previous studies have shown activation of right orbitofrontal cortex during judgments of odor familiarity. In the present study, we sought to extend our knowledge about the neural circuits involved in such a task by exploring the involvement of the right prefrontal areas and limbic/primary olfactory structures. Fourteen right-handed male subjects were tested using fMRI with a single functional run of two olfactory conditions (odor detection and familiarity judgments). Each condition included three epochs. During the familiarity condition, subjects rated whether odors were familiar or unfamiliar. During the detection condition, participants decided if odors were present. When contrasting the familiarity with the detection conditions, activated areas were found mainly in the right piriform cortex (PC) and hippocampus, the left inferior frontal gyrus and amygdala, and bilaterally in the mid-fusiform gyrus. Further analyses demonstrated that the right PC was more strongly activated than the left PC. This result supports the notion that the right PC is preferentially involved in judgments of odor familiarity.

Adolescent↗

PubMed2004

Lateralization of olfactory processes.

Over the last ten years, methods of cerebral imaging have revolutionized our knowledge of cognitive processes in humans. An impressive number of papers dealing with cerebral imaging for olfaction have been published to date. Whereas the early works revealed those structures participating in the processing of odours presented passively to subjects, researchers later recorded brain activity when subjects performed specific olfactory tasks based on memory, emotion and identification. From these results, we suggest that there is a dissociation of olfactory processes, with involvement of the right hemisphere in memory processes and the left hemisphere in emotional processes. The review concludes with a summary of how these lateralized processes are consistent with the gestalt-nature of our olfactory perception.

Amygdala↗

PubMed2003

Both of us disgusted in My insula: the common neural basis of seeing and feeling disgust.

What neural mechanism underlies the capacity to understand the emotions of others? Does this mechanism involve brain areas normally involved in experiencing the same emotion? We performed an fMRI study in which participants inhaled odorants producing a strong feeling of disgust. The same participants observed video clips showing the emotional facial expression of disgust. Observing such faces and feeling disgust activated the same sites in the anterior insula and to a lesser extent in the anterior cingulate cortex. Thus, as observing hand actions activates the observer's motor representation of that action, observing an emotion activates the neural representation of that emotion. This finding provides a unifying mechanism for understanding the behaviors of others.

Adult↗

PubMed2003

fMRI of emotional responses to odors: influence of hedonic valence and judgment, handedness, and gender.

Previous positron emission tomography studies of right-handed individuals show that the left orbitofrontal cortex is dominant during emotional processing of odors. We collected functional magnetic resonance imaging data from 28 subjects to study this network as a function of odor hedonic valence (pleasant vs. unpleasant), active hedonic judgments versus passive sensation of hedonically charged odors, handedness, and gender. Two functional runs were performed, with pleasant and unpleasant odors presented in different epochs. In the first run, subjects passively smelled odorants, whereas in the second run they rated degree of odor pleasantness or unpleasantness by using a "finger-span" technique that simulated a visual rating scale. Electrodermal and plethysmography responses were simultaneously recorded to control for covert, physiological manifestations of the emotional response. The piriform-amygdala area and ventral insula were activated more for unpleasant than pleasant odors. More extreme ratings were also associated with higher electrodermal amplitude, suggesting that activation stemmed more from emotional or hedonic intensity than valence, and that unpleasant odors induced more arousal than pleasant odors. Unpleasant odors activated the left ventral insula in right-handers and the right ventral insula in left-handers, suggesting lateralized processing of emotional odors as a function of handedness. Active decisions about odor pleasantness induced specific left orbitofrontal cortex activation, implicating the role of this area in the conscious assessment of the emotional quality of odors. Finally, left orbitofrontal cortex was more active in women than men, potentially in relation to women's well-documented advantage in odor identification.

Adult↗