Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Plailly, Jane; Howard, James D.; Gitelman, Darren R.; Gottfried, Jay A.

doi:10.1523/jneurosci.5607-07.2008

Cited by 189 publications

(168 citation statements)

References 57 publications

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“…PCG including perirhinal and entorhinal cortex is considered as the piriform cortex and accepts olfactory afferent from olfactory bulb via olfactory tract, and then projects to olfactory neocortical projection sites in the orbitofrontal cortex (OFC) [33,34,35], while OFC, as the secondary olfactory cortex, is involved in more advanced processing of smell by integrating olfactory afferent information, taste, visual and visceral sense via hypothalamic dorsomedial nucleus [34,36]. The order of involvement of PCG and OFC is consistent with the projection pathway of olfactory processing [22,33], and with the hypothesis of the caudorostral pathological process in PD [3,4].…”

Section: Discussionmentioning

confidence: 99%

“…Our results showed that progressive atrophy of the piriform cortex and OFC correlated with the impairment of olfactory detection function, while atrophy in right OFC correlated with olfactory identification dysfunction, suggesting that piriform cortex and OFC might be involved in different roles of the olfactory process. Previous studies showed that the direct pathway of projection from piriform cortex to olfactory OFC serves as a quick and sensitive detection of odor, while the indirect circle between piriform cortex and OFC with a discriminative capacity and the feedback connections from OFC involved with cognitive factors, such as attention, expectation, and memory [33,34,37,38]. Meanwhile, a study of combining functional magnetic resonance imaging, peripheral autonomic recordings, and olfactory psychophysics showed that right OFC is a central substrate for human olfactory consciousness [39].…”

Section: Discussionmentioning

confidence: 99%

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Correlation between Progressive Changes in Piriform Cortex and Olfactory Performance in Early Parkinson’s Disease

Wu¹,

Chen²,

Fan³

et al. 2011

Eur Neurol

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Objectives: The mechanism underlying olfactory dysfunction in Parkinson’s disease (PD) remains unknown. The current study aims to investigate the relationship between sequential changes of volume change of cortex associated with olfactory function and degree of deficiency of olfactory performance in PD. Methods: Based on the arbitrary cut-off score of olfactory performance measured by ‘five odors olfactory detection arrays’, subjects were classified into three groups: PD patients with olfactory impairment (OPD, n = 12), PD without olfactory impairment (NPD, n = 14), and healthy controls without olfactory impairment (NC, n = 26). A morphometric analysis of magnetic resonance images (voxel-based morphometry; VBM) was used to investigate cortical volume change. Results: The scores of olfactory performance were higher in both NPD and OPD groups than in the NC group independent of age and disease duration, indicating that NPD subjects did have board line deficiency of olfaction though not meet the cut-off score for abnormal olfactory function. Both NPD and OPD had cortical atrophy in the parahippocampal gyrus (PCG), but only OPD also had change in orbitofrontal cortex (OFC). Correlation analysis revealed that decrement of volumes of PCG and right OFC was associated with decreased olfactory detection sensitivity, and the right OFC was also correlated to olfactory identification. However, no correlation was found between structural changes and the severity of the disease measured by UPDRS score. Conclusions: The results confirmed that atrophy in piriform cortex and orbitofrontal cortex is associated with olfactory dysfunction in early PD. Atrophy of the orbitofrontal cortex becomes significant as olfactory damage progresses. Volume measurement of olfaction-associated areas together with the assessment of olfactory function may be a sensitive indicator for the early diagnosis of PD.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Correlation between Progressive Changes in Piriform Cortex and Olfactory Performance in Early Parkinson’s Disease

Wu¹,

Chen²,

Fan³

et al. 2011

Eur Neurol

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“…Olfactory stimuli are processed in at least two different anatomical ways. Pure olfactory odours such as vanillin or phenylethanol are processed in the olfactory bulb (sensitivity, discrimination and filtering), primary olfactory cortex comprising the piriform cortex (somatosensory input of the sniff [10] , habituation effects [11] ), thalamus (awareness of odours [12] ), hippocampus and amygdala (emotion and memory processing [13] ), and orbitofrontal cortex (e.g. identification, discrimination [13] ) [14] .…”

mentioning

confidence: 99%

Altered Frontal and Temporal Brain Function during Olfactory Stimulation in Adult Attention-Deficit/Hyperactivity Disorder

et al. 2010

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Objective: Olfactory processing depends on dopamine metabolism and orbitofrontal cortex functioning, both known to be disturbed in attention-deficit/hyperactivity disorder (ADHD). Some investigations suggested alterations in olfactory processing (identification and sensitivity) in childhood and adult ADHD. Methods: In the present study we investigated olfactory function (Sniffin’ Sticks) of 29 adult patients with ADHD (17 combined, 11 inattentive, and 1 hyperactive/impulsive subtype) and 29 controls matched for sex, handedness, age, intelligence, and education. Additionally, we measured frontal, temporal, and somatosensory cortical activity during olfactory perception. This was performed with functional near-infrared spectroscopy (fNIRS) during presentation of 2-phenylethanol (olfactory stimulant) and linalool (mixed olfactory/trigeminal stimulant) in two concentrations each. Results: Adult patients with ADHD and controls did not differ in sensitivity for and discrimination and identification of olfactory stimuli. Functional brain imaging measures with fNIRS generally revealed diminished activation in olfaction-associated brain regions in patients with ADHD. Only for a high concentration of linalool, oxygenated haemoglobin (O₂Hb) concentrations in patients were similar to controls (significant increase in the temporal, somatosensory, and inferior-frontal cortex). O₂Hb concentrations in active brain regions positively correlated with ADHD symptoms during childhood and trait impulsivity. These effects were carried for the subgroup with combined subtype. Conclusions: Although we could not replicate altered clinical performance in ADHD, our fNIRS findings suggest an association of cortical olfactory processing with hyperactivity and impulsivity in adult ADHD.

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“…However, several lines of evidence point to an indirect involvement of the mediodorsal (MD) thalamus in the sense of smell [4][5][6][7][8][9]. In contrast, the role of the ventrolateral (VL) thalamus in olfaction is unclear at present.…”

Section: Introductionmentioning

confidence: 99%

Involvement of the human ventrolateral thalamus in olfaction

Zobel

Hummel²,

Ilgner

et al. 2010

J Neurol

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It is widely assumed that the thalamus is not involved in olfaction. The ventrolateral thalamus is, however, closely connected to the contralateral cerebellum, which is involved in the sense of smell based on findings from functional imaging studies and findings of olfactory deficits in patients with cerebellar disease. We hypothesized that olfactory deficits following lesions of the ventrolateral thalamus may be similar to olfactory deficits following cerebellar lesions. Fifteen patients with a focal thalamic lesion involving the ventrolateral thalamus were examined and compared to 15 patients with a focal cerebellar lesion and 15 healthy controls. A detailed olfactory test ("Sniffin' Sticks") was used to assess different olfactory functions separately for each nostril. In the group of patients with a lesion of the ventrolateral thalamus, an impairment of the odor threshold was found at the ipsilateral nostril, consistent with the unilateral orientation of the olfactory system in the telencephalon. In the group of patients with a cerebellar lesion, an olfactory deficit at the contralesional nostril emerged. In controls, no significant side difference was found. The involvement of the ventrolateral thalamus in olfaction is comparable to that of the cerebellum in respect to odor threshold. Further study is needed to assess if these findings are related to an impairment of an olfactomotor loop. Present evidence for this hypothesis is indirect. Effects were subclinical as none of the patients reported olfactory disturbance. The results suggest that the cerebello-thalamic axis plays an adjuvant role in olfaction.

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Attention to Odor Modulates Thalamocortical Connectivity in the Human Brain

Cited by 189 publications

References 57 publications

Correlation between Progressive Changes in Piriform Cortex and Olfactory Performance in Early Parkinson’s Disease

Correlation between Progressive Changes in Piriform Cortex and Olfactory Performance in Early Parkinson’s Disease

Altered Frontal and Temporal Brain Function during Olfactory Stimulation in Adult Attention-Deficit/Hyperactivity Disorder

Involvement of the human ventrolateral thalamus in olfaction

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