A TMS Investigation on the Role of Lateral Occipital Complex and Caudal Intraparietal Sulcus in the Perception of Object Form and Orientation

2017 ◽  
Vol 29 (5) ◽  
pp. 881-895 ◽  
Author(s):  
Philippe A. Chouinard ◽  
Deiter K. Meena ◽  
Robert L. Whitwell ◽  
Matthew D. Hilchey ◽  
Melvyn A. Goodale
Keyword(s):  
Critical Role ◽  
Brain Regions ◽  
Orientation Discrimination ◽  
Experimental Session ◽  
Intraparietal Sulcus ◽  
Lateral Occipital Complex ◽  
Match To Sample ◽  
Form Processing ◽  
Object Form ◽  
Object Features

We used TMS to assess the causal roles of the lateral occipital (LO) and caudal intraparietal sulcus (cIPS) areas in the perceptual discrimination of object features. All participants underwent fMRI to localize these areas using a protocol in which they passively viewed images of objects that varied in both form and orientation. fMRI identified six significant brain regions: LO, cIPS, and the fusiform gyrus, bilaterally. In a separate experimental session, we applied TMS to LO or cIPS while the same participants performed match-to-sample form or orientation discrimination tasks. Compared with sham stimulation, TMS to either the left or right LO increased RTs for form but not orientation discrimination, supporting a critical role for LO in form processing for perception- and judgment-based tasks. In contrast, we did not observe any effects when we applied TMS to cIPS. Thus, despite the clear functional evidence of engagement for both LO and cIPS during the passive viewing of objects in the fMRI experiment, the TMS experiment revealed that cIPS is not critical for making perceptual judgments about their form or orientation.

scholarly journals Analysis of haptic information in the cerebral cortex

2016 ◽  
Vol 116 (4) ◽  
pp. 1795-1806 ◽  
Author(s):  
K. Sathian
Keyword(s):  
Cerebral Cortex ◽  
Somatosensory Cortex ◽  
Visual Information ◽  
Occipital Cortex ◽  
Brain Regions ◽  
Primary Somatosensory Cortex ◽  
Intraparietal Sulcus ◽  
Haptic Information ◽  
Lateral Occipital Complex ◽  
Shape Processing

Haptic sensing of objects acquires information about a number of properties. This review summarizes current understanding about how these properties are processed in the cerebral cortex of macaques and humans. Nonnoxious somatosensory inputs, after initial processing in primary somatosensory cortex, are partially segregated into different pathways. A ventrally directed pathway carries information about surface texture into parietal opercular cortex and thence to medial occipital cortex. A dorsally directed pathway transmits information regarding the location of features on objects to the intraparietal sulcus and frontal eye fields. Shape processing occurs mainly in the intraparietal sulcus and lateral occipital complex, while orientation processing is distributed across primary somatosensory cortex, the parietal operculum, the anterior intraparietal sulcus, and a parieto-occipital region. For each of these properties, the respective areas outside primary somatosensory cortex also process corresponding visual information and are thus multisensory. Consistent with the distributed neural processing of haptic object properties, tactile spatial acuity depends on interaction between bottom-up tactile inputs and top-down attentional signals in a distributed neural network. Future work should clarify the roles of the various brain regions and how they interact at the network level.

The melanocortin-3 receptor is a pharmacological target for the regulation of anorexia

2021 ◽  
Vol 13 (590) ◽  
pp. eabd6434
Author(s):  
Patrick Sweeney ◽  
Michelle N. Bedenbaugh ◽  
Jose Maldonado ◽  
Pauline Pan ◽  
Katelyn Fowler ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Feeding Behavior ◽  
Critical Role ◽  
Brain Regions ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Female Mice ◽  
Bidirectional Regulation ◽  
Fear And Anxiety ◽  
Agouti Related Protein

Ablation of hypothalamic AgRP (Agouti-related protein) neurons is known to lead to fatal anorexia, whereas their activation stimulates voracious feeding and suppresses other motivational states including fear and anxiety. Despite the critical role of AgRP neurons in bidirectionally controlling feeding, there are currently no therapeutics available specifically targeting this circuitry. The melanocortin-3 receptor (MC3R) is expressed in multiple brain regions and exhibits sexual dimorphism of expression in some of those regions in both mice and humans. MC3R deletion produced multiple forms of sexually dimorphic anorexia that resembled aspects of human anorexia nervosa. However, there was no sexual dimorphism in the expression of MC3R in AgRP neurons, 97% of which expressed MC3R. Chemogenetic manipulation of arcuate MC3R neurons and pharmacologic manipulation of MC3R each exerted potent bidirectional regulation over feeding behavior in male and female mice, whereas global ablation of MC3R-expressing cells produced fatal anorexia. Pharmacological effects of MC3R compounds on feeding were dependent on intact AgRP circuitry in the mice. Thus, the dominant effect of MC3R appears to be the regulation of the AgRP circuitry in both male and female mice, with sexually dimorphic sites playing specialized and subordinate roles in feeding behavior. Therefore, MC3R is a potential therapeutic target for disorders characterized by anorexia, as well as a potential target for weight loss therapeutics.

scholarly journals Uncovering the spatio-temporal dynamics of value-based decision-making in the human brain: a combined fMRI–EEG study

2014 ◽  
Vol 369 (1655) ◽  
pp. 20130473 ◽  
Author(s):  
Tobias Larsen ◽  
John P. O'Doherty
Keyword(s):  
Decision Making ◽  
Prefrontal Cortex ◽  
Temporal Dynamics ◽  
Brain Regions ◽  
Choice Task ◽  
Binary Choice ◽  
Intraparietal Sulcus ◽  
Trial Onset ◽  
Eeg Data ◽  
Spatio Temporal

While there is a growing body of functional magnetic resonance imaging (fMRI) evidence implicating a corpus of brain regions in value-based decision-making in humans, the limited temporal resolution of fMRI cannot address the relative temporal precedence of different brain regions in decision-making. To address this question, we adopted a computational model-based approach to electroencephalography (EEG) data acquired during a simple binary choice task. fMRI data were also acquired from the same participants for source localization. Post-decision value signals emerged 200 ms post-stimulus in a predominantly posterior source in the vicinity of the intraparietal sulcus and posterior temporal lobe cortex, alongside a weaker anterior locus. The signal then shifted to a predominantly anterior locus 850 ms following the trial onset, localized to the ventromedial prefrontal cortex and lateral prefrontal cortex. Comparison signals between unchosen and chosen options emerged late in the trial at 1050 ms in dorsomedial prefrontal cortex, suggesting that such comparison signals may not be directly associated with the decision itself but rather may play a role in post-decision action selection. Taken together, these results provide us new insights into the temporal dynamics of decision-making in the brain, suggesting that for a simple binary choice task, decisions may be encoded predominantly in posterior areas such as intraparietal sulcus, before shifting anteriorly.

Glutamate in the pathophysiology of schizophrenia

2020 ◽  
pp. 287-296
Author(s):  
Daniel C. Javitt
Keyword(s):  
Visual System ◽  
Visual Processing ◽  
Negative Symptoms ◽  
Glutamate Release ◽  
Critical Role ◽  
Brain Regions ◽  
Long Term Memory ◽  
Subcortical Structures ◽  
Impaired Metabolism

Glutamate theories of schizophrenia were first proposed over 30 years ago and since that time have become increasingly accepted. Theories are supported by the ability of N-methyl-D-aspartate receptor (NMDAR) antagonists such as phencyclidine (PCP) or ketamine to induce symptoms that closely resemble those of schizophrenia. Moreover, NMDAR antagonists uniquely reproduce the level of negative symptoms and cognitive deficits observed in schizophrenia, suggesting that such models may be particularly appropriate to poor outcome forms of the disorder. As opposed to dopamine, which is most prominent within frontostriatal brain regions, glutamate neurons are present throughout cortex and subcortical structures. Thus, NMDAR theories predict widespread disturbances across cortical and thalamic pathways, including sensory brain regions. In auditory cortex, NMDAR play a critical role in the generation of mismatch negativity (MMN), which may therefore serve as a translational marker of NMDAR dysfunction across species. In the visual system, NMDAR play a critical role in function of the magnocellular visual system. Deficits in both auditory and visual processing contribute to social and communication deficits, which, in turn, lead to poor functional outcome. By contrast, NMDAR dysfunction within the frontohippocampal system may contribute to well described deficits in working memory, executive processing and long-term memory formation. Deficits in NMDAR function may be driven by disturbances in presynaptic glutamate release, impaired metabolism of NMDAR modulators such as glycine or D-serine, or intrinsic abnormalities in NMDAR themselves.

scholarly journals The Human Intraparietal Sulcus Modulates Task-Evoked Functional Connectivity

2019 ◽  
Vol 30 (3) ◽  
pp. 875-887
Author(s):  
Kai Hwang ◽  
James M Shine ◽  
Dillan Cellier ◽  
Mark D’Esposito
Keyword(s):  
Functional Connectivity ◽  
Temporal Cortex ◽  
Brain Regions ◽  
Intraparietal Sulcus ◽  
Top Down ◽  
Adaptive Communication ◽  
Wide Range ◽  
Functional Connectivity Strength ◽  
Ventral Temporal Cortex ◽  
Cortical Regions

Abstract Past studies have demonstrated that flexible interactions between brain regions support a wide range of goal-directed behaviors. However, the neural mechanisms that underlie adaptive communication between brain regions are not well understood. In this study, we combined theta-burst transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging to investigate the sources of top-down biasing signals that influence task-evoked functional connectivity. Subjects viewed sequences of images of faces and buildings and were required to detect repetitions (2-back vs. 1-back) of the attended stimuli category (faces or buildings). We found that functional connectivity between ventral temporal cortex and the primary visual cortex (VC) increased during processing of task-relevant stimuli, especially during higher memory loads. Furthermore, the strength of functional connectivity was greater for correct trials. Increases in task-evoked functional connectivity strength were correlated with increases in activity in multiple frontal, parietal, and subcortical (caudate and thalamus) regions. Finally, we found that TMS to superior intraparietal sulcus (IPS), but not to primary somatosensory cortex, decreased task-specific modulation in connectivity patterns between the primary VC and the parahippocampal place area. These findings demonstrate that the human IPS is a source of top-down biasing signals that modulate task-evoked functional connectivity among task-relevant cortical regions.

scholarly journals C-19 An fMRI Study of Age-Associated Changes in Basic Visual Discrimination

2019 ◽  
Vol 34 (6) ◽  
pp. 1048-1048
Author(s):  
T Seider ◽  
E Porges ◽  
A Woods ◽  
R Cohen
Keyword(s):  
Visual Processing ◽  
Visual Discrimination ◽  
Community Sample ◽  
Visual Assessment ◽  
Brain Regions ◽  
Brain Response ◽  
Match To Sample ◽  
Fmri Study ◽  
Perceptual Skill ◽  
Cluster Level

Abstract Objective The study was conducted to determine age-associated changes in functional brain response, measured with fMRI, during visual discrimination with regard to three elementary components of visual perception: shape, location, and velocity. A secondary aim was to validate the method used to isolate the hypothesized brain regions associated with these perceptual functions. Method Items from the Visual Assessment Battery (VAB), a simultaneous match-to-sample task, assessed visual discrimination in 40 healthy adults during fMRI. Participants were aged 51-91 and recruited from a larger community sample for a study on normal aging. The tasks were designed to isolate neural recruitment during discrimination of either location, shape, or velocity by using tasks that were identical aside from the perceptual skill required to complete them. Results The Location task uniquely activated the dorsal visual processing stream, the Shape task the ventral stream, and the Velocity task V5/MT. Greater age was associated with greater neural recruitment, particularly in frontal areas (uncorrected voxel-level p < .001, family-wise error cluster-level p□.05). Conclusions Results validated the specialization of brain regions for spatial, perceptual, and movement discriminations and the use of the VAB to assess functioning localized to these regions. Anterior neural recruitment during visual discrimination increases with age.

Multivariate fMRI and Eye Tracking Reveal Differential Effects of Visual Interference on Recognition Memory Judgments for Objects and Scenes

2015 ◽  
Vol 27 (9) ◽  
pp. 1708-1722 ◽  
Author(s):  
Edward B. O'Neil ◽  
Hilary C. Watson ◽  
Sonya Dhillon ◽  
Nancy J. Lobaugh ◽  
Andy C. H. Lee
Keyword(s):  
Object Recognition ◽  
Recognition Memory ◽  
Brain Regions ◽  
Scene Recognition ◽  
Visual Object ◽  
Object Representations ◽  
Match To Sample ◽  
Visual Interference ◽  
Correct Object ◽  
Recognition Judgments

Recent work has demonstrated that the perirhinal cortex (PRC) supports conjunctive object representations that aid object recognition memory following visual object interference. It is unclear, however, how these representations interact with other brain regions implicated in mnemonic retrieval and how congruent and incongruent interference influences the processing of targets and foils during object recognition. To address this, multivariate partial least squares was applied to fMRI data acquired during an interference match-to-sample task, in which participants made object or scene recognition judgments after object or scene interference. This revealed a pattern of activity sensitive to object recognition following congruent (i.e., object) interference that included PRC, prefrontal, and parietal regions. Moreover, functional connectivity analysis revealed a common pattern of PRC connectivity across interference and recognition conditions. Examination of eye movements during the same task in a separate study revealed that participants gazed more at targets than foils during correct object recognition decisions, regardless of interference congruency. By contrast, participants viewed foils more than targets for incorrect object memory judgments, but only after congruent interference. Our findings suggest that congruent interference makes object foils appear familiar and that a network of regions, including PRC, is recruited to overcome the effects of interference.

Human Brain Regions Involved in Visual Discriminations

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 298-298
Author(s):  
G A Orban
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Brain Regions ◽  
Orientation Discrimination ◽  
National Academy Of Sciences ◽  
Temporal Comparison ◽  
Dot Motion ◽  
Speed Discrimination ◽  
Academy Of Sciences ◽  
Visual Discriminations

We have used simple visual discriminations as a tool to investigate the human visual system with PET and fMRI. In discrimination tasks, stimuli in which an attribute is defined by a cue are presented in a position in the visual field and the subjects compare the stimuli with each other or with a standard. We have manipulated each of these four aspects. Manipulation of stimulus position engages visuo-spatial attention mechanisms in parietal and frontal cortex (Vandenberghe et al, 1996 Brain119 1263 – 1276; 1997 Journal of Neuroscience in press). Manipulation of the cue has revealed the kinetic occipital (KO) region involved in the processing of kinetic contours (Orban et al, 1995 Proceedings of the National Academy of Sciences of the USA92 993 – 997; Dupont et al, 1997 Cerebral Cortex in press). Using luminance-defined patterns presented centrally and contrasting successive orientation discrimination with identification we have demonstrated the involvement of right fusiform cortex in temporal comparison of orientation (Orban et al, 1997 European Journal of Neurosciences9 246 – 259). The same region is involved in spatial comparison of orientation as well as in temporal comparison of speed and direction of random-dot motion. This set of experiments shows that processing in the human visual system depends not only on the attribute used but also on the nature of the task to be performed. The direction and speed discrimination experiments also reveal the involvement of the lingual motion area in these tasks, but surprisingly very little involvement of human MT/V5.

scholarly journals Excitatory/inhibitory neuronal metabolic balance in mouse hippocampus upon infusion of [U-13C6]glucose

2020 ◽  
pp. 0271678X2091053
Author(s):  
Antoine Cherix ◽  
Guillaume Donati ◽  
Blanca Lizarbe ◽  
Bernard Lanz ◽  
Carole Poitry-Yamate ◽  
...  
Keyword(s):  
Critical Role ◽  
Tca Cycle ◽  
Brain Regions ◽  
Inhibitory Neurons ◽  
Resonance Spectroscopy ◽  
Spectral Fitting ◽  
Mouse Hippocampus ◽  
And Behavior ◽  
Gabaergic Activity

Hippocampus plays a critical role in linking brain energetics and behavior typically associated to stress exposure. In this study, we aimed to simultaneously assess excitatory and inhibitory neuronal metabolism in mouse hippocampus in vivo by applying 18FDG-PET and indirect 13C magnetic resonance spectroscopy (1H-[13C]-MRS) at 14.1 T upon infusion of uniformly 13C-labeled glucose ([U-13C6]Glc). Improving the spectral fitting by taking into account variable decoupling efficiencies of [U-13C6]Glc and refining the compartmentalized model by including two γ-aminobutyric acid (GABA) pools permit us to evaluate the relative contributions of glutamatergic and GABAergic metabolism to total hippocampal neuroenergetics. We report that GABAergic activity accounts for ∼13% of total neurotransmission (VNT) and ∼27% of total neuronal TCA cycle (VTCA) in mouse hippocampus suggesting a higher VTCA/VNT ratio for inhibitory neurons compared to excitatory neurons. Finally, our results provide new strategies and tools for bringing forward the developments and applications of 13C-MRS in specific brain regions of small animals.

The role of the cerebellum in creativity and expert stone knapping

2020 ◽  
pp. 105971232096646
Author(s):  
Frederick L Coolidge
Keyword(s):  
Critical Role ◽  
Brain Regions ◽  
Stone Tool ◽  
Fine Motor ◽  
Engagement Theory ◽  
Motor Movements ◽  
And Function ◽  
The Mind ◽  
Stone Knapping

The purpose of this article is to review the evolution and function of the cerebellum, particularly in regard to its role in creativity and expert stone knapping. First, the article reviews the history of the cerebellum, its evolution and phylogenetics, and its concerted evolution with various brain regions. It also notes the critical role of the cerebellum and the cerebro-cerebellar network in its traditionally recognized control of gross and fine motor movements and in its exaptation for basic and higher level cognitive processes, particularly in regard to increasingly more sophisticated stone knapping. Also, reviewed are various theories, advanced over the past three decades, of how the cerebellum tweaks and refines thoughts, images, and ideas just as it refines and smooths motor movements. Baddeley’s working memory model is also prominently featured, as are the works of Ito, Vandervert, and others on the cerebellum’s role in novel problem-solving, insight, and creativity. Finally, this article reviews two “Cognitive Rubicons” in stone tool knapping, Theory of Mind and stone knapping, and Malafouris’ Material Engagement Theory. The article concludes with a novel hypothesis that the automaticity provided by the cerebellum derived from extensive practice in stone knapping may have freed Baddeley’s central executive from its attentional demands and allows the mind to “wander and wonder.”

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