scholarly journals Normal Olfactory Functional Connectivity Despite Lifelong Absence of Olfactory Experiences

2020 ◽  
Vol 31 (1) ◽  
pp. 159-168
Author(s):  
Moa G Peter ◽  
Peter Fransson ◽  
Gustav Mårtensson ◽  
Elbrich M Postma ◽  
Love Engström Nordin ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Morphological Changes ◽  
Olfactory Cortex ◽  
Sensory Loss ◽  
Congenital Blindness ◽  
Primary Olfactory Cortex ◽  
Normal Functional ◽  
Olfactory Processing ◽  
Cortical Regions ◽  
Visual Cortical

Abstract Congenital blindness is associated with atypical morphology and functional connectivity within and from visual cortical regions; changes that are hypothesized to originate from a lifelong absence of visual input and could be regarded as a general (re) organization principle of sensory cortices. Challenging this is the fact that individuals with congenital anosmia (lifelong olfactory sensory loss) display little to no morphological changes in the primary olfactory cortex. To determine whether olfactory input from birth is essential to establish and maintain normal functional connectivity in olfactory processing regions, akin to the visual system, we assessed differences in functional connectivity within the olfactory cortex between individuals with congenital anosmia (n = 33) and matched controls (n = 33). Specifically, we assessed differences in connectivity between core olfactory processing regions as well as differences in regional homogeneity and homotopic connectivity within the primary olfactory cortex. In contrast to congenital blindness, none of the analyses indicated atypical connectivity in individuals with congenital anosmia. In fact, post-hoc Bayesian analysis provided support for an absence of group differences. These results suggest that a lifelong absence of olfactory experience has a limited impact on the functional connectivity in the olfactory cortex, a finding that indicates a clear difference between sensory modalities in how sensory cortical regions develop.

scholarly journals Normal Olfactory Functional Connectivity Despite Life-Long Absence of Olfactory Experiences

2020 ◽  
Author(s):  
Moa G. Peter ◽  
Peter Fransson ◽  
Gustav Mårtensson ◽  
Elbrich M. Postma ◽  
Love Engström Nordin ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Morphological Changes ◽  
Olfactory Cortex ◽  
Sensory Loss ◽  
Congenital Blindness ◽  
Primary Olfactory Cortex ◽  
Normal Functional ◽  
Olfactory Processing ◽  
Cortical Regions ◽  
Visual Cortical

ABSTRACTCongenital blindness is associated with atypical morphology, and functional connectivity within and from, visual cortical regions; changes that are hypothesized to originate from a life-long absence of visual input and could be regarded as a general (re)organization principle of sensory cortices. Challenging this is the fact that individuals with congenital anosmia (life-long olfactory sensory loss) display little to no morphological changes in primary olfactory cortex. To determine whether olfactory input from birth is essential to establish and maintain normal functional connectivity in olfactory processing regions, akin to the visual system, we assessed differences in functional connectivity within olfactory cortex between individuals with congenital anosmia (n=33) and matched controls (n=34). Specifically, we assessed differences in connectivity between core olfactory processing regions as well as differences in regional homogeneity and homotopic connectivity within primary olfactory cortex. In contrast to congenital blindness, none of the analyses indicated atypical connectivity in individuals with congenital anosmia. In fact, post-hoc Bayesian analysis provided support for an absence of group differences. These results suggest that a lifelong absence of olfactory experience has limited impact on the functional connectivity in olfactory cortex, a finding that indicates a clear difference between sensory modalities in how sensory cortical regions develop.

scholarly journals Characterizing functional pathways of the human olfactory system

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Guangyu Zhou ◽  
Gregory Lane ◽  
Shiloh L Cooper ◽  
Thorsten Kahnt ◽  
Christina Zelano
Keyword(s):  
Functional Connectivity ◽  
Olfactory System ◽  
Large Scale ◽  
Brain Structures ◽  
Olfactory Cortex ◽  
Data Set ◽  
Whole Brain ◽  
Central Processing ◽  
Primary Olfactory Cortex ◽  
Processing Pathways

The central processing pathways of the human olfactory system are not fully understood. The olfactory bulb projects directly to a number of cortical brain structures, but the distinct networks formed by projections from each of these structures to the rest of the brain have not been well-defined. Here, we used functional magnetic resonance imaging and k-means clustering to parcellate human primary olfactory cortex into clusters based on whole-brain functional connectivity patterns. Resulting clusters accurately corresponded to anterior olfactory nucleus, olfactory tubercle, and frontal and temporal piriform cortices, suggesting dissociable whole-brain networks formed by the subregions of primary olfactory cortex. This result was replicated in an independent data set. We then characterized the unique functional connectivity profiles of each subregion, producing a map of the large-scale processing pathways of the human olfactory system. These results provide insight into the functional and anatomical organization of the human olfactory system.

scholarly journals The effect of congenital blindness on resting-state functional connectivity revisited

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria J. S. Guerreiro ◽  
Madita Linke ◽  
Sunitha Lingareddy ◽  
Ramesh Kekunnaya ◽  
Brigitte Röder
Keyword(s):  
Functional Connectivity ◽  
Resting State ◽  
Visual Experience ◽  
Brain Regions ◽  
State Condition ◽  
Resting State Functional Connectivity ◽  
Congenital Blindness ◽  
Eyes Closed ◽  
Congenitally Blind ◽  
Eyes Open

AbstractLower resting-state functional connectivity (RSFC) between ‘visual’ and non-‘visual’ neural circuits has been reported as a hallmark of congenital blindness. In sighted individuals, RSFC between visual and non-visual brain regions has been shown to increase during rest with eyes closed relative to rest with eyes open. To determine the role of visual experience on the modulation of RSFC by resting state condition—as well as to evaluate the effect of resting state condition on group differences in RSFC—, we compared RSFC between visual and somatosensory/auditory regions in congenitally blind individuals (n = 9) and sighted participants (n = 9) during eyes open and eyes closed conditions. In the sighted group, we replicated the increase of RSFC between visual and non-visual areas during rest with eyes closed relative to rest with eyes open. This was not the case in the congenitally blind group, resulting in a lower RSFC between ‘visual’ and non-‘visual’ circuits relative to sighted controls only in the eyes closed condition. These results indicate that visual experience is necessary for the modulation of RSFC by resting state condition and highlight the importance of considering whether sighted controls should be tested with eyes open or closed in studies of functional brain reorganization as a consequence of blindness.

scholarly journals The Role of Primate Prefrontal Cortex in Bias and Shift Between Visual Dimensions

2019 ◽  
Vol 30 (1) ◽  
pp. 85-99 ◽  
Author(s):  
Farshad A Mansouri ◽  
Mark J Buckley ◽  
Daniel J Fehring ◽  
Keiji Tanaka
Keyword(s):  
Prefrontal Cortex ◽  
Anterior Cingulate ◽  
Top Down ◽  
Attentional Processes ◽  
Prefrontal Cortical ◽  
Frontopolar Cortex ◽  
Dorsolateral Prefrontal ◽  
Cortical Regions ◽  
Visual Cortical ◽  
Bilateral Lesions

Abstract Imaging and neural activity recording studies have shown activation in the primate prefrontal cortex when shifting attention between visual dimensions is necessary to achieve goals. A fundamental unanswered question is whether representations of these dimensions emerge from top-down attentional processes mediated by prefrontal regions or from bottom-up processes within visual cortical regions. We hypothesized a causative link between prefrontal cortical regions and dimension-based behavior. In large cohorts of humans and macaque monkeys, performing the same attention shifting task, we found that both species successfully shifted between visual dimensions, but both species also showed a significant behavioral advantage/bias to a particular dimension; however, these biases were in opposite directions in humans (bias to color) versus monkeys (bias to shape). Monkeys’ bias remained after selective bilateral lesions within the anterior cingulate cortex (ACC), frontopolar cortex, dorsolateral prefrontal cortex (DLPFC), orbitofrontal cortex (OFC), or superior, lateral prefrontal cortex. However, lesions within certain regions (ACC, DLPFC, or OFC) impaired monkeys’ ability to shift between these dimensions. We conclude that goal-directed processing of a particular dimension for the executive control of behavior depends on the integrity of prefrontal cortex; however, representation of competing dimensions and bias toward them does not depend on top-down prefrontal-mediated processes.

scholarly journals Frequency dependence and gender effects in visual cortical regions involved in temporal frequency dependent pattern processing

2001 ◽  
Vol 14 (1) ◽  
pp. 28-38 ◽  
Author(s):  
Christian Kaufmann ◽  
Gregor-Konstantin Elbel ◽  
Christoff Gössl ◽  
Benno Pütz ◽  
Dorothee P. Auer
Keyword(s):  
Frequency Dependence ◽  
Temporal Frequency ◽  
Gender Effects ◽  
Frequency Dependent ◽  
Pattern Processing ◽  
And Gender ◽  
Cortical Regions ◽  
Visual Cortical

scholarly journals Effects of amnesia on processing in the hippocampus and default mode network during a naturalistic memory task: a case study

2018 ◽  
Author(s):  
Christiane Oedekoven ◽  
James L. Keidel ◽  
Stuart Anderson ◽  
Angus Nisbet ◽  
Chris Bird
Keyword(s):  
Functional Connectivity ◽  
Episodic Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Structural Mri ◽  
Brain Regions ◽  
Left Hippocampus ◽  
Cortical Regions ◽  
The Right ◽  
Encoding And Retrieval

Despite their severely impaired episodic memory, individuals with amnesia are able to comprehend ongoing events. Online representations of a current event are thought to be supported by a network of regions centred on the posterior midline cortex (PMC). By contrast, episodic memory is widely believed to be supported by interactions between the hippocampus and these cortical regions. In this MRI study, we investigated the encoding and retrieval of lifelike events (video clips) in a patient with severe amnesia likely resulting from a stroke to the right thalamus, and a group of 20 age-matched controls. Structural MRI revealed grey matter reductions in left hippocampus and left thalamus in comparison to controls. We first characterised the regions activated in the controls while they watched and retrieved the videos. There were no differences in activation between the patient and controls in any of the regions. We then identified a widespread network of brain regions, including the hippocampus, that were functionally connected with the PMC in controls. However, in the patient there was a specific reduction in functional connectivity between the PMC and a region of left hippocampus when both watching and attempting to retrieve the videos. A follow up analysis revealed that in controls the functional connectivity between these regions when watching the videos was correlated with memory performance. Taken together, these findings support the view that the interactions between the PMC and the hippocampus enable the encoding and retrieval of multimodal representations of the contents of an event.

Functional Connectivity Relationships Predict Similarities in Task Activation and Pattern Information during Associative Memory Encoding

2014 ◽  
Vol 26 (5) ◽  
pp. 1085-1099 ◽  
Author(s):  
Maureen Ritchey ◽  
Andrew P. Yonelinas ◽  
Charan Ranganath
Keyword(s):  
Functional Connectivity ◽  
Functional Properties ◽  
Associative Memory ◽  
Large Scale ◽  
Memory Task ◽  
Neural Systems ◽  
General Level ◽  
Specific Information ◽  
Memory Encoding ◽  
Cortical Regions

Neural systems may be characterized by measuring functional interactions in the healthy brain, but it is unclear whether components of systems defined in this way share functional properties. For instance, within the medial temporal lobes (MTL), different subregions show different patterns of cortical connectivity. It is unknown, however, whether these intrinsic connections predict similarities in how these regions respond during memory encoding. Here, we defined brain networks using resting state functional connectivity (RSFC) then quantified the functional similarity of regions within each network during an associative memory encoding task. Results showed that anterior MTL regions affiliated with a network of anterior temporal cortical regions, whereas posterior MTL regions affiliated with a network of posterior medial cortical regions. Importantly, these connectivity relationships also predicted similarities among regions during the associative memory task. Both in terms of task-evoked activation and trial-specific information carried in multivoxel patterns, regions within each network were more similar to one another than were regions in different networks. These findings suggest that functional heterogeneity among MTL subregions may be related to their participation in distinct large-scale cortical systems involved in memory. At a more general level, the results suggest that components of neural systems defined on the basis of RSFC share similar functional properties in terms of recruitment during cognitive tasks and information carried in voxel patterns.

Disorders of the Cranial Nerves and Brainstem

2021 ◽  
pp. 851-861
Author(s):  
Kelly D. Flemming
Keyword(s):  
Olfactory Bulb ◽  
Olfactory Receptor ◽  
Cranial Nerves ◽  
Olfactory Nerve ◽  
Mitral Cell ◽  
Olfactory Cortex ◽  
Olfactory Receptor Cells ◽  
Receptor Cells ◽  
Clinical Disorders ◽  
Primary Olfactory Cortex

This chapter briefly repeats key anatomic characteristics and then reviews clinical disorders affecting each cranial nerve in addition to the brainstem. More specifically, this chapter covers cranial nerves I, V, VII, and IX through XII plus the brainstem. The olfactory nerve is a special visceral afferent nerve that functions in the sense of smell. The axons of the olfactory receptor cells within the nasal cavity extend through the cribriform plate to the olfactory bulb. These olfactory receptor cell axons synapse with mitral cells in the olfactory bulb. Mitral cell axons project to the primary olfactory cortex and amygdala. The olfactory cortex interconnects with various autonomic and visceral centers.

Time Course of Odorant-Induced Activation in the Human Primary Olfactory Cortex

2000 ◽  
Vol 83 (1) ◽  
pp. 537-551 ◽  
Author(s):  
Noam Sobel ◽  
Vivek Prabhakaran ◽  
Zuo Zhao ◽  
John E. Desmond ◽  
Gary H. Glover ◽  
...  
Keyword(s):  
Time Course ◽  
Piriform Cortex ◽  
Signal Amplitude ◽  
Olfactory Cortex ◽  
Transient Increase ◽  
Functional Neuroanatomy ◽  
Functional Magnetic Resonance ◽  
Physiological Level ◽  
Temporal Variance ◽  
Primary Olfactory Cortex

Paradoxically, attempts to visualize odorant-induced functional magnetic resonance imaging (fMRI) activation in the human have yielded activations in secondary olfactory regions but not in the primary olfactory cortex-piriform cortex. We show that odorant-induced activation in primary olfactory cortex was not previously made evident with fMRI because of the unique time course of activity in this region: in primary olfactory cortex, odorants induced a strong early transient increase in signal amplitude that then habituated within 30–40 s of odorant presence. This time course of activation seen here in the primary olfactory cortex of the human is almost identical to that recorded electrophysiologically in the piriform cortex of the rat. Mapping activation with analyses that are sensitive to both this transient increase in signal amplitude, and temporal-variance, enabled us to use fMRI to consistently visualize odorant-induced activation in the human primary olfactory cortex. The combination of continued accurate odorant detection at the behavioral level despite primary olfactory cortex habituation at the physiological level suggests that the functional neuroanatomy of the olfactory response may change throughout prolonged olfactory stimulation.

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