The Experts below are selected from a list of 1554 Experts worldwide ranked by ideXlab platform

Donald A. Wilson - One of the best experts on this subject based on the ideXlab platform.

  • task correlated cortical asymmetry and intra and inter hemispheric separation
    Scientific Reports, 2017
    Co-Authors: Donald A. Wilson, Yaniv Cohen
    Abstract:

    Cerebral lateralization is expressed at both the structural and functional levels, and can exist as either a stable characteristic or as a dynamic feature during behavior and development. The anatomically relatively simple Olfactory system demonstrates lateralization in both human and non-human animals. Here, we explored functional lateralization in both Primary Olfactory Cortex – a region critical for odor memory and perception- and orbitofrontal Cortex (OFC) – a region involved in reversal learning- in rats performing an odor learning and reversal task. We find significant asymmetry in both Olfactory and orbitofrontal cortical odor-evoked activity, which is expressed in a performance- and task-dependent manner. The emergence of learning-dependent asymmetry during reversal learning was associated with decreased functional connectivity both between the bilateral OFC and between the OFC-Olfactory Cortex. The results suggest an inter-hemispheric asymmetry and Olfactory cortical functional separation that may allow multiple, specialized processing circuits to emerge during a reversal task requiring behavioral flexibility.

  • the Olfactory thalamus unanswered questions about the role of the mediodorsal thalamic nucleus in olfaction
    Frontiers in Neural Circuits, 2015
    Co-Authors: Emmanuelle Courtiol, Donald A. Wilson
    Abstract:

    The mediodorsal thalamic nucleus (MDT) is a higher order thalamic nucleus and its role in cognition is increasingly well established. Interestingly, components of the MDT also have a somewhat unique sensory function as they link Primary Olfactory Cortex to orbitofrontal associative Cortex. In fact, anatomical evidence firmly demonstrates that the MDT receives direct input from Primary Olfactory areas including the piriform Cortex and has dense reciprocal connections with the orbitofrontal Cortex. The functions of this Olfactory pathway have been poorly explored but lesion, imaging, and electrophysiological studies suggest that these connections may be involved in Olfactory processing including odor perception, discrimination, learning, and attention. However, many important questions regarding the MDT and olfaction remain unanswered. Our goal here is not only to briefly review the existing literature but also to highlight some of the remaining questions that need to be answered to better define the role(s) of the MDT in Olfactory processing.

Noam Sobel - One of the best experts on this subject based on the ideXlab platform.

  • A specialized odor memory buffer in Primary Olfactory Cortex. PLoS One (2009
    2016
    Co-Authors: Christina Zelano, Rehan Khan, Jessica Montag, Noam Sobel
    Abstract:

    Background: The neural substrates of Olfactory working memory are unknown. We addressed the questions of whether Olfactory working memory involves a verbal representation of the odor, or a sensory image of the odor, or both, and the location of the neural substrates of these processes. Methodology/Principal Findings: We used functional magnetic resonance imaging to measure activity in the brains of subjects who were remembering either nameable or unnameable odorants. We found a double dissociation whereby remembering nameable odorants was reflected in sustained activity in prefrontal language areas, and remembering unnameable odorants was reflected in sustained activity in Primary Olfactory Cortex. Conclusions/Significance: These findings suggest a novel dedicated mechanism in Primary Olfactory Cortex, where odor information is maintained in temporary storage to subserve ongoing tasks

  • a specialized odor memory buffer in Primary Olfactory Cortex
    PLOS ONE, 2009
    Co-Authors: Christina Zelano, Jessica Lena Montag, Rehan M Khan, Noam Sobel
    Abstract:

    Background The neural substrates of Olfactory working memory are unknown. We addressed the questions of whether Olfactory working memory involves a verbal representation of the odor, or a sensory image of the odor, or both, and the location of the neural substrates of these processes. Methodology/Principal Findings We used functional magnetic resonance imaging to measure activity in the brains of subjects who were remembering either nameable or unnameable odorants. We found a double dissociation whereby remembering nameable odorants was reflected in sustained activity in prefrontal language areas, and remembering unnameable odorants was reflected in sustained activity in Primary Olfactory Cortex. Conclusions/Significance These findings suggest a novel dedicated mechanism in Primary Olfactory Cortex, where odor information is maintained in temporary storage to subserve ongoing tasks.

  • dissociated representations of irritation and valence in human Primary Olfactory Cortex
    Journal of Neurophysiology, 2007
    Co-Authors: Christina Zelano, Rehan M Khan, Noam Sobel, Jessica L Montag, B R Johnson
    Abstract:

    Irritation and negative valence are closely associated in perception. However, these perceptual aspects can be dissociated in olfaction where irritation can accompany both pleasant and unpleasant o...

  • Attentional modulation in human Primary Olfactory Cortex
    Nature Neuroscience, 2005
    Co-Authors: Christina Zelano, Moustafa Bensafi, Jess Porter, Joel Mainland, Brad Johnson, Elizabeth Bremner, Christina Telles, Rehan Khan, Noam Sobel
    Abstract:

    Central to the concept of attention is the fact that identical stimuli can be processed in different ways. In olfaction, attention may designate the identical flow of air through the nose as either respiration or Olfactory exploration. Here we have used functional magnetic resonance imaging (fMRI) to probe this attentional mechanism in Primary Olfactory Cortex (POC). We report a dissociation in POC that revealed attention-dependent and attention-independent subregions. Whereas a temporal subregion comprising temporal piriform Cortex (PirT) responded equally across conditions, a frontal subregion comprising frontal piriform Cortex (PirF) and the Olfactory tubercle responded preferentially to attended sniffs as opposed to unattended sniffs. In addition, a task-specific anticipatory response occurred in the attention-dependent region only. This dissociation was consistent across two experimental designs: one focusing on sniffs of clean air, the other focusing on odor-laden sniffs. Our findings highlight the role of attention at the earliest cortical levels of Olfactory processing.

  • time course of odorant induced activation in the human Primary Olfactory Cortex
    Journal of Neurophysiology, 2000
    Co-Authors: Noam Sobel, Vivek Prabhakaran, Zuo Zhao, John E Desmond, Gary H Glover, Edith V Sullivan, John D E Gabrieli
    Abstract:

    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 prim...

Emmanuelle Courtiol - One of the best experts on this subject based on the ideXlab platform.

  • the Olfactory thalamus unanswered questions about the role of the mediodorsal thalamic nucleus in olfaction
    Frontiers in Neural Circuits, 2015
    Co-Authors: Emmanuelle Courtiol, Donald A. Wilson
    Abstract:

    The mediodorsal thalamic nucleus (MDT) is a higher order thalamic nucleus and its role in cognition is increasingly well established. Interestingly, components of the MDT also have a somewhat unique sensory function as they link Primary Olfactory Cortex to orbitofrontal associative Cortex. In fact, anatomical evidence firmly demonstrates that the MDT receives direct input from Primary Olfactory areas including the piriform Cortex and has dense reciprocal connections with the orbitofrontal Cortex. The functions of this Olfactory pathway have been poorly explored but lesion, imaging, and electrophysiological studies suggest that these connections may be involved in Olfactory processing including odor perception, discrimination, learning, and attention. However, many important questions regarding the MDT and olfaction remain unanswered. Our goal here is not only to briefly review the existing literature but also to highlight some of the remaining questions that need to be answered to better define the role(s) of the MDT in Olfactory processing.

Christina Zelano - One of the best experts on this subject based on the ideXlab platform.

  • A specialized odor memory buffer in Primary Olfactory Cortex. PLoS One (2009
    2016
    Co-Authors: Christina Zelano, Rehan Khan, Jessica Montag, Noam Sobel
    Abstract:

    Background: The neural substrates of Olfactory working memory are unknown. We addressed the questions of whether Olfactory working memory involves a verbal representation of the odor, or a sensory image of the odor, or both, and the location of the neural substrates of these processes. Methodology/Principal Findings: We used functional magnetic resonance imaging to measure activity in the brains of subjects who were remembering either nameable or unnameable odorants. We found a double dissociation whereby remembering nameable odorants was reflected in sustained activity in prefrontal language areas, and remembering unnameable odorants was reflected in sustained activity in Primary Olfactory Cortex. Conclusions/Significance: These findings suggest a novel dedicated mechanism in Primary Olfactory Cortex, where odor information is maintained in temporary storage to subserve ongoing tasks

  • a specialized odor memory buffer in Primary Olfactory Cortex
    PLOS ONE, 2009
    Co-Authors: Christina Zelano, Jessica Lena Montag, Rehan M Khan, Noam Sobel
    Abstract:

    Background The neural substrates of Olfactory working memory are unknown. We addressed the questions of whether Olfactory working memory involves a verbal representation of the odor, or a sensory image of the odor, or both, and the location of the neural substrates of these processes. Methodology/Principal Findings We used functional magnetic resonance imaging to measure activity in the brains of subjects who were remembering either nameable or unnameable odorants. We found a double dissociation whereby remembering nameable odorants was reflected in sustained activity in prefrontal language areas, and remembering unnameable odorants was reflected in sustained activity in Primary Olfactory Cortex. Conclusions/Significance These findings suggest a novel dedicated mechanism in Primary Olfactory Cortex, where odor information is maintained in temporary storage to subserve ongoing tasks.

  • dissociated representations of irritation and valence in human Primary Olfactory Cortex
    Journal of Neurophysiology, 2007
    Co-Authors: Christina Zelano, Rehan M Khan, Noam Sobel, Jessica L Montag, B R Johnson
    Abstract:

    Irritation and negative valence are closely associated in perception. However, these perceptual aspects can be dissociated in olfaction where irritation can accompany both pleasant and unpleasant o...

  • Attentional modulation in human Primary Olfactory Cortex
    Nature Neuroscience, 2005
    Co-Authors: Christina Zelano, Moustafa Bensafi, Jess Porter, Joel Mainland, Brad Johnson, Elizabeth Bremner, Christina Telles, Rehan Khan, Noam Sobel
    Abstract:

    Central to the concept of attention is the fact that identical stimuli can be processed in different ways. In olfaction, attention may designate the identical flow of air through the nose as either respiration or Olfactory exploration. Here we have used functional magnetic resonance imaging (fMRI) to probe this attentional mechanism in Primary Olfactory Cortex (POC). We report a dissociation in POC that revealed attention-dependent and attention-independent subregions. Whereas a temporal subregion comprising temporal piriform Cortex (PirT) responded equally across conditions, a frontal subregion comprising frontal piriform Cortex (PirF) and the Olfactory tubercle responded preferentially to attended sniffs as opposed to unattended sniffs. In addition, a task-specific anticipatory response occurred in the attention-dependent region only. This dissociation was consistent across two experimental designs: one focusing on sniffs of clean air, the other focusing on odor-laden sniffs. Our findings highlight the role of attention at the earliest cortical levels of Olfactory processing.

Kurt R Illig - One of the best experts on this subject based on the ideXlab platform.

  • projections from orbitofrontal Cortex to anterior piriform Cortex in the rat suggest a role in Olfactory information processing
    The Journal of Comparative Neurology, 2005
    Co-Authors: Kurt R Illig
    Abstract:

    The orbitofrontal Cortex (OFC) has been characterized as a higher-order, multimodal sensory Cortex. Evidence from electrophysiological and behavioral studies in the rat has suggested that OFC plays a role in modulating Olfactory guided behavior, and a significant projection to OFC arises from piriform Cortex, the traditional Primary Olfactory Cortex. To discern how OFC interacts with Primary Olfactory structures, the anterograde tracer Phaseolus vulgaris leucoagglutinin was injected into orbitofrontal cortical areas in adult male rats. Labeled fibers were found in the piriform Cortex and Olfactory bulb on the side ipsilateral to the injection. Notably, the projection to piriform Cortex was predominantly from ventrolateral orbital Cortex, and was not uniform; rostrally, the projection to the ventral portion of the anterior piriform Cortex (APC) was substantial, while the dorsal APC was virtually free of labeled fibers. Labeled fibers were found in both the dorsal and ventral portions in more caudal regions of APC. Most labeled fibers were found in layer III, although a substantial number of fibers were observed in layers Ib and II. Labeled fibers in posterior piriform Cortex also were seen after injection into orbitofrontal areas. Taken together with previous reports, these findings suggest that piriform Cortex includes multiple subdivisions, which may perform separate, parallel functions in Olfactory information processing. Further, these results suggest that the OFC, in addition to its putative role in encoding information about the significance of Olfactory stimuli, may play a role in modulating odor response properties of neurons in piriform Cortex.

  • new features of connectivity in piriform Cortex visualized by intracellular injection of pyramidal cells suggest that Primary Olfactory Cortex functions like association Cortex in other sensory systems
    The Journal of Neuroscience, 2000
    Co-Authors: Dawn M G Johnson, Kurt R Illig, Mary Behan, Lewis B. Haberly
    Abstract:

    Associational connections of pyramidal cells in rat posterior piriform Cortex were studied by direct visualization of axons stained by intracellular injection in vivo . The results revealed that individual cells have widespread axonal arbors that extend over nearly the full length of the cerebral hemisphere. Within piriform Cortex these arbors are highly distributed with no regularly arranged patchy concentrations like those associated with the columnar organization in other Primary sensory areas (i.e., where periodically arranged sets of cells have common response properties, inputs, and outputs). A lack of columnar organization was also indicated by a marked disparity in the intrinsic projection patterns of neighboring injected cells. Analysis of axonal branching patterns, bouton distributions, and dendritic arbors suggested that each pyramidal cell makes a small number of synaptic contacts on a large number (>1000) of other cells in piriform Cortex at disparate locations. Axons from individual pyramidal cells also arborize extensively within many neighboring cortical areas, most of which send strong projections back to piriform Cortex. These include areas involved in high-order functions in prefrontal, amygdaloid, entorhinal, and perirhinal Cortex, to which there are few projections from other Primary sensory areas. Our results suggest that piriform Cortex performs correlative functions analogous to those in association areas of neoCortex rather than those typical of Primary sensory areas with which it has been traditionally classed. Findings from other studies suggest that the Olfactory bulb subserves functions performed by Primary areas in other sensory systems.