Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Humans (132)
- Male (123)
- Female (94)
- Adult (67)
- Magnetic Resonance Imaging (61)
-
- Animals (59)
- Young Adult (48)
- Brain Mapping (44)
- Brain (33)
- Photic Stimulation (30)
- Learning (29)
- Memory (29)
- Adolescent (27)
- Psychomotor Performance (25)
- Computer-Assisted (23)
- Psychological (23)
- Reaction Time (22)
- Visual Perception (21)
- Image Processing, Computer-Assisted (20)
- Acoustic Stimulation (18)
- Hippocampus (18)
- Image Processing (18)
- Neurons (18)
- Pattern Recognition (18)
- Visual (18)
- Child (17)
- Rats (17)
- Evoked Potentials (16)
- Middle Aged (16)
- Models (16)
- Publication Year
Articles 331 - 360 of 380
Full-Text Articles in Neurosciences
Motor Output Evoked By Subsaccadic Stimulation Of Primate Frontal Eye Fields., Brian D Corneil, James K Elsley, Benjamin Nagy, Sharon L Cushing
Motor Output Evoked By Subsaccadic Stimulation Of Primate Frontal Eye Fields., Brian D Corneil, James K Elsley, Benjamin Nagy, Sharon L Cushing
Brain and Mind Institute Researchers' Publications
In addition to its role in shifting the line of sight, the oculomotor system is also involved in the covert orienting of visuospatial attention. Causal evidence supporting this premotor theory of attention, or oculomotor readiness hypothesis, comes from the effect of subsaccadic threshold stimulation of the oculomotor system on behavior and neural activity in the absence of evoked saccades, which parallels the effects of covert attention. Here, by recording neck-muscle activity from monkeys and systematically titrating the level of stimulation current delivered to the frontal eye fields (FEF), we show that such subsaccadic stimulation is not divorced from immediate motor …
Theta-Activity In Anterior Cingulate Cortex Predicts Task Rules And Their Adjustments Following Errors, Thilo Womelsdorf, Kevin Johnston, Martin Vinck, Stefan Everling
Theta-Activity In Anterior Cingulate Cortex Predicts Task Rules And Their Adjustments Following Errors, Thilo Womelsdorf, Kevin Johnston, Martin Vinck, Stefan Everling
Brain and Mind Institute Researchers' Publications
Accomplishing even simple tasks depend on neuronal circuits to configure how incoming sensory stimuli map onto responses. Controlling these stimulus-response (SR) mapping rules relies on a cognitive control network comprising the anterior cingulate cortex (ACC). Single neurons within the ACC convey information about currently relevant SR mapping rules and signal unexpected action outcomes, which can be used to optimize behavioral choices. However, its functional significance and the mechanistic means of interaction with other nodes of the cognitive control network remain elusive and poorly understood. Here, we report that core aspects of cognitive control are encoded by rhythmic theta-band activity within …
Running Enhances Spatial Pattern Separation In Mice., David J Creer, Carola Romberg, Lisa M Saksida, Henriette Van Praag, Timothy J Bussey
Running Enhances Spatial Pattern Separation In Mice., David J Creer, Carola Romberg, Lisa M Saksida, Henriette Van Praag, Timothy J Bussey
Brain and Mind Institute Researchers' Publications
Increasing evidence suggests that regular exercise improves brain health and promotes synaptic plasticity and hippocampal neurogenesis. Exercise improves learning, but specific mechanisms of information processing influenced by physical activity are unknown. Here, we report that voluntary running enhanced the ability of adult (3 months old) male C57BL/6 mice to discriminate between the locations of two adjacent identical stimuli. Improved spatial pattern separation in adult runners was tightly correlated with increased neurogenesis. In contrast, very aged (22 months old) mice had impaired spatial discrimination and low basal cell genesis that was refractory to running. These findings suggest that the addition of …
Adapting To Dynamic Stimulus-Response Values: Differential Contributions Of Inferior Frontal, Dorsomedial, And Dorsolateral Regions Of Prefrontal Cortex To Decision Making., Derek G V Mitchell, Qian Luo, Shelley B Avny, Tomasz Kasprzycki, Karanvir Gupta, Gang Chen, Elizabeth C Finger, R James R Blair
Adapting To Dynamic Stimulus-Response Values: Differential Contributions Of Inferior Frontal, Dorsomedial, And Dorsolateral Regions Of Prefrontal Cortex To Decision Making., Derek G V Mitchell, Qian Luo, Shelley B Avny, Tomasz Kasprzycki, Karanvir Gupta, Gang Chen, Elizabeth C Finger, R James R Blair
Brain and Mind Institute Researchers' Publications
Dorsomedial prefrontal cortex (dmPFC), dorsolateral prefrontal cortex (dlPFC), and inferior frontal gyrus (IFG) have all been implicated in resolving decision conflict whether this conflict is generated by having to select between responses of similar value or by making selections following a reversal in reinforcement contingencies. However, work distinguishing their individual functional contributions remains preliminary. We used functional magnetic resonance imaging to delineate the functional role of these systems with regard to both forms of decision conflict. Within dmPFC and dlPFC, blood oxygen level-dependent responses increased in response to decision conflict regardless of whether the conflict occurred in the context of …
Perirhinal Cortex Contributes To Accuracy In Recognition Memory And Perceptual Discriminations., Edward B O'Neil, Anthony D Cate, Stefan Köhler
Perirhinal Cortex Contributes To Accuracy In Recognition Memory And Perceptual Discriminations., Edward B O'Neil, Anthony D Cate, Stefan Köhler
Brain and Mind Institute Researchers' Publications
The prevailing view of the medial temporal lobe (MTL) holds that its structures are dedicated to long-term declarative memory. Recent evidence challenges this position, suggesting that perirhinal cortex (PRc) in the MTL may also play a role in perceptual discriminations of stimuli with substantial visual feature overlap. Relevant neuropsychological findings in humans have been inconclusive, likely because studies have relied on patients with large and variable MTL lesions. Here, we conducted a functional magnetic resonance imaging study in healthy individuals to determine whether PRc shows a performance-related involvement in perceptual oddball judgments that is comparable to its established role in …
Illusory Vowels Resulting From Perceptual Continuity: A Functional Magnetic Resonance Imaging Study, Antje Heinrich, Robert P Carlyon, Matthew H Davis, Ingrid Johnsrude
Illusory Vowels Resulting From Perceptual Continuity: A Functional Magnetic Resonance Imaging Study, Antje Heinrich, Robert P Carlyon, Matthew H Davis, Ingrid Johnsrude
Brain and Mind Institute Researchers' Publications
We used functional magnetic resonance imaging to study the neural processing of vowels whose perception depends on the continuity illusion. Participants heard sequences of two-formant vowels under a number of listening conditions. In the "vowel conditions," both formants were always present simultaneously and the stimuli were perceived as speech-like. Contrasted with a range of nonspeech sounds, these vowels elicited activity in the posterior middle temporal gyrus (MTG) and superior temporal sulcus (STS). When the two formants alternated in time, the "speech-likeness" of the sounds was reduced. It could be partially restored by filling the silent gaps in each formant with …
Freesurfer-Initiated Fully-Automated Subcortical Brain Segmentation In Mri Using Large Deformation Diffeomorphic Metric Mapping., Ali R Khan, Lei Wang, Mirza Faisal Beg
Freesurfer-Initiated Fully-Automated Subcortical Brain Segmentation In Mri Using Large Deformation Diffeomorphic Metric Mapping., Ali R Khan, Lei Wang, Mirza Faisal Beg
Brain and Mind Institute Researchers' Publications
Fully-automated brain segmentation methods have not been widely adopted for clinical use because of issues related to reliability, accuracy, and limitations of delineation protocol. By combining the probabilistic-based FreeSurfer (FS) method with the Large Deformation Diffeomorphic Metric Mapping (LDDMM)-based label-propagation method, we are able to increase reliability and accuracy, and allow for flexibility in template choice. Our method uses the automated FreeSurfer subcortical labeling to provide a coarse-to-fine introduction of information in the LDDMM template-based segmentation resulting in a fully-automated subcortical brain segmentation method (FS+LDDMM). One major advantage of the FS+LDDMM-based approach is that the automatically generated segmentations generated are …
Effects Of Acute Ethyl Alcohol Consumption On A Psychophysical Measure Of Lateral Inhibition In Human Vision., Kevin D Johnston, Brian Timney
Effects Of Acute Ethyl Alcohol Consumption On A Psychophysical Measure Of Lateral Inhibition In Human Vision., Kevin D Johnston, Brian Timney
Brain and Mind Institute Researchers' Publications
Acute consumption of ethyl alcohol affects a variety of visual functions. However, there have been few systematic attempts to investigate the neural mechanisms underlying these effects. Here, we employed the Westheimer paradigm to investigate the hypothesis that alcohol reduces lateral inhibition within human "perceptive fields", the psychophysical analogue of physiological receptive fields. Westheimer functions obtained under alcohol and no-alcohol conditions at photopic, mesopic, and scotopic levels of adaptation showed changes consistent with an alcohol-induced decrease in lateral inhibition. We conclude that this decrease in lateral inhibition may be responsible for some of the changes in visual perception that result from …
Functional Imaging Of The Auditory Processing Applied To Speech Sounds, Roy D Patterson, Ingrid Johnsrude
Functional Imaging Of The Auditory Processing Applied To Speech Sounds, Roy D Patterson, Ingrid Johnsrude
Brain and Mind Institute Researchers' Publications
In this paper, we describe domain-general auditory processes that we believe are prerequisite to the linguistic analysis of speech. We discuss biological evidence for these processes and how they might relate to processes that are specific to human speech and language. We begin with a brief review of (i) the anatomy of the auditory system and (ii) the essential properties of speech sounds. Section 4 describes the general auditory mechanisms that we believe are applied to all communication sounds, and how functional neuroimaging is being used to map the brain networks associated with domain-general auditory processing. Section 5 discusses recent …
Dissociating Speech Perception And Comprehension At Reduced Levels Of Awareness, Matthew H Davis, Martin R Coleman, Anthony R Absalom, Jennifer M Rodd, Ingrid Johnsrude, Basil F Matta, Adrian M Owen, David K Menon
Dissociating Speech Perception And Comprehension At Reduced Levels Of Awareness, Matthew H Davis, Martin R Coleman, Anthony R Absalom, Jennifer M Rodd, Ingrid Johnsrude, Basil F Matta, Adrian M Owen, David K Menon
Brain and Mind Institute Researchers' Publications
We used functional MRI and the anesthetic agent propofol to assess the relationship among neural responses to speech, successful comprehension, and conscious awareness. Volunteers were scanned while listening to sentences containing ambiguous words, matched sentences without ambiguous words, and signal-correlated noise (SCN). During three scanning sessions, participants were nonsedated (awake), lightly sedated (a slowed response to conversation), and deeply sedated (no conversational response, rousable by loud command). Bilateral temporal-lobe responses for sentences compared with signal-correlated noise were observed at all three levels of sedation, although prefrontal and premotor responses to speech were absent at the deepest level of sedation. Additional …
Human Parietal "Reach Region" Primarily Encodes Intrinsic Visual Direction, Not Extrinsic Movement Direction, In A Visual Motor Dissociation Task., Juan Fernandez-Ruiz, Herbert C Goltz, Joseph F X Desouza, Tutis Vilis, J Douglas Crawford
Human Parietal "Reach Region" Primarily Encodes Intrinsic Visual Direction, Not Extrinsic Movement Direction, In A Visual Motor Dissociation Task., Juan Fernandez-Ruiz, Herbert C Goltz, Joseph F X Desouza, Tutis Vilis, J Douglas Crawford
Brain and Mind Institute Researchers' Publications
Posterior parietal cortex (PPC) participates in the planning of visuospatial behaviors, including reach movements, in gaze-centered coordinates. It is not known if these representations encode the visual goal in retinal coordinates, or the movement direction relative to gaze. Here, by dissociating the intrinsic retinal stimulus from the extrinsic direction of movement, we show that PPC employs a visual code. Using delayed pointing and event-related functional magnetic resonance imaging, we identified a cluster of PPC regions whose activity was topographically (contralaterally) related to the direction of the planned movement. We then switched the normal visual-motor spatial relationship by adapting subjects to …
Do Vegetative Patients Retain Aspects Of Language Comprehension? Evidence From Fmri, Martin R Coleman, Jennifer M Rodd, Matthew H Davis, Ingrid Johnsrude, David K Menon, John D Pickard, Adrian M Owen
Do Vegetative Patients Retain Aspects Of Language Comprehension? Evidence From Fmri, Martin R Coleman, Jennifer M Rodd, Matthew H Davis, Ingrid Johnsrude, David K Menon, John D Pickard, Adrian M Owen
Brain and Mind Institute Researchers' Publications
A diagnosis of vegetative state is made if a patient demonstrates no evidence of awareness of self or environment, no evidence of sustained, reproducible, purposeful or voluntary behavioural response to sensory stimuli and critically no evidence of language comprehension. For those patients who retain peripheral motor function, rigorous behavioural assessment is usually able to determine retained function. However, some patients do not retain the ability to respond overtly to command and it is becoming increasingly accepted that assessment of these patients should include techniques, which do not rely on any 'motor action' on the part of the patient. Here, we …
Alcohol Slows Interhemispheric Transmission, Increases The Flash-Lag Effect, And Prolongs Masking: Evidence For A Slowing Of Neural Processing And Transmission., Sarah A Khan, Brian Timney
Alcohol Slows Interhemispheric Transmission, Increases The Flash-Lag Effect, And Prolongs Masking: Evidence For A Slowing Of Neural Processing And Transmission., Sarah A Khan, Brian Timney
Brain and Mind Institute Researchers' Publications
While the alcohol literature is extensive, relatively little addresses the relationship between physiological effects and behavioural changes. Using the visual system as a model, we examined alcohol's influence on neural temporal processing as a potential means for alcohol's effects. We did this by using tasks that provided a measure of processing speed: Poffenberger paradigm, flash-lag, and backward masking. After moderate alcohol, participants showed longer interhemispheric transmission times, larger flash-lags, and prolonged masking. Our data are consistent with the view that alcohol slows neural processing, and provide support for a reduction in processing efficiency underlying alcohol-induced changes in temporal visual processing.
Relevance To Self: A Brief Review And Framework Of Neural Systems Underlying Appraisal, Taylor W. Schmitz, Sterling C. Johnson
Relevance To Self: A Brief Review And Framework Of Neural Systems Underlying Appraisal, Taylor W. Schmitz, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
We argue that many similar findings observed in cognitive, affective, and social neuroimaging research may compose larger processes central to generating self-relevance. In support of this, recent findings from these research domains were reviewed to identify common systemic activation patterns. Superimposition of these patterns revealed evidence for large-scale supramodal processes, which are argued to mediate appraisal of self-relevant content irrespective of specific stimulus types (e.g. words, pictures) and task domains (e.g. induction of reward, fear, pain, etc.). Furthermore, we distinguish between two top-down sub-systems involved in appraisal of self-relevance, one that orients pre-attentive biasing information (e.g. anticipatory or mnemonic) to …
Perceptual Functions Of Perirhinal Cortex In Rats: Zero-Delay Object Recognition And Simultaneous Oddity Discriminations., Susan J Bartko, Boyer D Winters, Rosemary A Cowell, Lisa M Saksida, Timothy J Bussey
Perceptual Functions Of Perirhinal Cortex In Rats: Zero-Delay Object Recognition And Simultaneous Oddity Discriminations., Susan J Bartko, Boyer D Winters, Rosemary A Cowell, Lisa M Saksida, Timothy J Bussey
Brain and Mind Institute Researchers' Publications
The perirhinal cortex (PRh) is widely accepted as having an important role in object recognition memory in humans and animals. Contrary to claims that PRh mediates declarative memory exclusively, previous evidence suggests that PRh has a role in the perceptual processing of complex objects. In the present study, we conducted an examination of the possible role of PRh in perceptual function in rats. We examined whether bilateral excitotoxic lesions of PRh or PPRh (perirhinal plus postrhinal cortices) in the rat would cause deficits in a zero-delay object-recognition task and a simultaneous oddity discrimination task. Both of these tasks measured spontaneous …
Anosognosia In Mild Cognitive Impairment: Relationship To Activation Of Cortical Midline Structures Involved In Self-Appraisal, Michele L. Ries, Britta M. Jabbar, Taylor W. Schmitz, Mehul A. Trivedi, Carey E. Gleason, Cynthia M. Carlsson, Howard A. Rowley, Sanjay Asthana, Sterling C. Johnson
Anosognosia In Mild Cognitive Impairment: Relationship To Activation Of Cortical Midline Structures Involved In Self-Appraisal, Michele L. Ries, Britta M. Jabbar, Taylor W. Schmitz, Mehul A. Trivedi, Carey E. Gleason, Cynthia M. Carlsson, Howard A. Rowley, Sanjay Asthana, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
Awareness of cognitive dysfunction shown by individuals with Mild Cognitive Impairment (MCI), a condition conferring risk for Alzheimer's disease (AD), is variable. Anosognosia, or unawareness of loss of function, is beginning to be recognized as an important clinical symptom of MCI. However, little is known about the brain substrates underlying this symptom. We hypothesized that MCI participants' activation of cortical midline structures (CMS) during self-appraisal would covary with level of insight into cognitive difficulties (indexed by a discrepancy score between patient and informant ratings of cognitive decline in each MCI participant). To address this hypothesis, we first compared 16 MCI …
Hormone Effects On Fmri And Cognitive Measures Of Encoding: Importance Of Hormone Preparation, C. E. Gleason, T. W. Schmitz, T. Hess, R. L. Koscik, M. A. Trivedi, M. L. Ries, C. M. Carlsson, M. A. Sager, S. Asthana, S. C. Johnson
Hormone Effects On Fmri And Cognitive Measures Of Encoding: Importance Of Hormone Preparation, C. E. Gleason, T. W. Schmitz, T. Hess, R. L. Koscik, M. A. Trivedi, M. L. Ries, C. M. Carlsson, M. A. Sager, S. Asthana, S. C. Johnson
Brain and Mind Institute Researchers' Publications
We compared fMRI and cognitive data from nine hormone therapy (HT)-naive women with data from women exposed to either opposed conjugated equine estrogens (CEE) (n = 10) or opposed estradiol (n = 4). Exposure to either form of HT was associated with healthier fMRI response; however, CEE-exposed women exhibited poorer memory performance than either HT-naive or estradiol-exposed subjects. These preliminary findings emphasize the need to characterize differential neural effects of various HTs. ©2006AAN Enterprises, Inc.
Activation Of Brain Regions Vulnerable To Alzheimer's Disease: The Effect Of Mild Cognitive Impairment, S. C. Johnson, T. W. Schmitz, C. H. Moritz, M. E. Meyerand, H. A. Rowley, A. L. Alexander, K. W. Hansen, C. E. Gleason, C. M. Carlsson, M. L. Ries, S. Asthana, K. Chen, E. M. Reiman, G. E. Alexander
Activation Of Brain Regions Vulnerable To Alzheimer's Disease: The Effect Of Mild Cognitive Impairment, S. C. Johnson, T. W. Schmitz, C. H. Moritz, M. E. Meyerand, H. A. Rowley, A. L. Alexander, K. W. Hansen, C. E. Gleason, C. M. Carlsson, M. L. Ries, S. Asthana, K. Chen, E. M. Reiman, G. E. Alexander
Brain and Mind Institute Researchers' Publications
This study examined the functionality of the medial temporal lobe (MTL) and posterior cingulate (PC) in mild cognitive impairment amnestic type (MCI), a syndrome that puts patients at greater risk for developing Alzheimer disease (AD). Functional MRI (fMRI) was used to identify regions normally active during encoding of novel items and recognition of previously learned items in a reference group of 77 healthy young and middle-aged adults. The pattern of activation in this group guided further comparisons between 14 MCI subjects and 14 age-matched controls. The MCI patients exhibited less activity in the PC during recognition of previously learned items, …
Structural Mri Discriminates Individuals With Mild Cognitive Impairment From Age-Matched Controls: A Combined Neuropsychological And Voxel Based Morphometry Study, Mehul A. Trivedi, Allison K. Wichmann, Britta M. Torgerson, Michael A. Ward, Taylor W. Schmitz, Michele L. Ries, Rebecca L. Koscik, Sanjay Asthana, Sterling C. Johnson
Structural Mri Discriminates Individuals With Mild Cognitive Impairment From Age-Matched Controls: A Combined Neuropsychological And Voxel Based Morphometry Study, Mehul A. Trivedi, Allison K. Wichmann, Britta M. Torgerson, Michael A. Ward, Taylor W. Schmitz, Michele L. Ries, Rebecca L. Koscik, Sanjay Asthana, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
Background: Several previous studies have reported that amnestic mild cognitive impairment (aMCI), a significant risk factor for Alzheimer's disease (AD), is associated with greater atrophy in the medial temporal lobe (MTL) and posterior cingulate gyrus (PCG). Method: In the present study, we examined the cross-sectional accuracy (i.e., the sensitivity and specificity) of voxel-based morphometry (VBM) in discriminating individuals with MCI (n = 15) from healthy age-matched controls (n = 15). In addition, we also sought to determine whether baseline GM volume predicted aMCI patients that converted to AD from those that did not approximately 2 years after the baseline visit. …
Paradoxical Facilitation Of Object Recognition Memory After Infusion Of Scopolamine Into Perirhinal Cortex: Implications For Cholinergic System Function., Boyer D Winters, Lisa M Saksida, Timothy J Bussey
Paradoxical Facilitation Of Object Recognition Memory After Infusion Of Scopolamine Into Perirhinal Cortex: Implications For Cholinergic System Function., Boyer D Winters, Lisa M Saksida, Timothy J Bussey
Brain and Mind Institute Researchers' Publications
The cholinergic system has long been implicated in learning and memory, yet its specific function remains unclear. In the present study, we investigated the role of cortical acetylcholine in a rodent model of declarative memory by infusing the cholinergic muscarinic receptor antagonist scopolamine into the rat perirhinal cortex during different stages (encoding, storage/consolidation, and retrieval) of the spontaneous object recognition task. Presample infusions of scopolamine significantly impaired object recognition compared with performance of the same group of rats on saline trials; this result is consistent with previous reports supporting a role for perirhinal acetylcholine in object information acquisition. Scopolamine infusions …
Representation Of Head-Centric Flow In The Human Motion Complex., Jeroen Goossens, Sean P Dukelow, Ravi S Menon, Tutis Vilis, Albert V Van Den Berg
Representation Of Head-Centric Flow In The Human Motion Complex., Jeroen Goossens, Sean P Dukelow, Ravi S Menon, Tutis Vilis, Albert V Van Den Berg
Brain and Mind Institute Researchers' Publications
Recent neuroimaging studies have identified putative homologs of macaque middle temporal area (area MT) and medial superior temporal area (area MST) in humans. Little is known about the integration of visual and nonvisual signals in human motion areas compared with monkeys. Through extra-retinal signals, the brain can factor out the components of visual flow on the retina that are induced by eye-in-head and head-in-space rotations and achieve a representation of flow relative to the head (head-centric flow) or body (body-centric flow). Here, we used functional magnetic resonance imaging to test whether extra-retinal eye-movement signals modulate responses to visual flow in …
Self-Appraisal Decisions Evoke Dissociated Dorsal-Ventral Ampfc Networks, Taylor W. Schmitz, Sterling C. Johnson
Self-Appraisal Decisions Evoke Dissociated Dorsal-Ventral Ampfc Networks, Taylor W. Schmitz, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
The anterior medial prefrontal cortex (aMPFC) is consistently active during personally salient decisions, yet the differential contributory processes of this region along the dorsal-ventral axis are less understood. Using a self-appraisal decision-making task and functional magnetic resonance imaging, we demonstrated task-dependent connectivity of ventral aMPFC with amygdala, insula, and nucleus accumbens, and dorsal aMPFC connectivity with dorsolateral PFC and bilateral hippocampus. These aMPFC networks appear to subserve distinct contributory processes inherent to self-appraisal decisions, specifically a dorsally mediated cognitive and a ventrally mediated affective/self-relevance network. © 2005 Elsevier Inc. All rights reserved.
Task-Dependent Posterior Cingulate Activation In Mild Cognitive Impairment, Michele L. Ries, Taylor W. Schmitz, Tisha N. Kawahara, Britta M. Torgerson, Mehul A. Trivedi, Sterling C. Johnson
Task-Dependent Posterior Cingulate Activation In Mild Cognitive Impairment, Michele L. Ries, Taylor W. Schmitz, Tisha N. Kawahara, Britta M. Torgerson, Mehul A. Trivedi, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
Neuroimaging research has demonstrated that the posterior cingulate cortex (PCC) is functionally compromised in individuals diagnosed with amnestic mild cognitive impairment (MCI), a major risk factor for the development of Alzheimer's disease (AD). In functional MRI studies with healthy participants, this same region is active during self-appraisal (requiring retrieval of semantic knowledge about the self) as well as episodic recognition of previously learned information. Administering both types of tasks to people with MCI may reveal important information on the role of the PCC in recollection. This study investigated fMRI activation in the PCC in individuals with MCI and matched controls …
Reduced Hippocampal Activation During Episodic Encoding In Middle-Aged Individuals At Genetic Risk Of Alzheimer's Disease: A Cross-Sectional Study, Mehul A. Trivedi, Taylor W. Schmitz, Michele L. Ries, Britta M. Torgerson, Mark A. Sager, Bruce P. Hermann, Sanjay Asthana, Sterling C. Johnson
Reduced Hippocampal Activation During Episodic Encoding In Middle-Aged Individuals At Genetic Risk Of Alzheimer's Disease: A Cross-Sectional Study, Mehul A. Trivedi, Taylor W. Schmitz, Michele L. Ries, Britta M. Torgerson, Mark A. Sager, Bruce P. Hermann, Sanjay Asthana, Sterling C. Johnson
Brain and Mind Institute Researchers' Publications
Background: The presence of the apolipoprotein E (APOE) ε4 allele is a major risk factor for the development of Alzheimer's disease (AD), and has been associated with metabolic brain changes several years before the onset of typical AD symptoms. Functional MRI (fMRI) is a brain imaging technique that has been used to demonstrate hippocampal activation during measurement of episodic encoding, but the effect of the ε4 allelle on hippocampal activation has not been firmly established. Methods: The present study examined the effects of APOE genotype on brain activation patterns in the media[ temporal lobe (MTL) during an episodic encoding task …
The Cerebral Response During Subjective Choice With And Without Self-Reference, Sterling C. Johnson, Taylor W. Schmitz, Tisha N. Kawahara-Baccus, Howard A. Rowley, Andrew L. Alexander, Jonghoon Lee, Richard J. Davidson
The Cerebral Response During Subjective Choice With And Without Self-Reference, Sterling C. Johnson, Taylor W. Schmitz, Tisha N. Kawahara-Baccus, Howard A. Rowley, Andrew L. Alexander, Jonghoon Lee, Richard J. Davidson
Brain and Mind Institute Researchers' Publications
The anterior medial prefrontal (AMPFC) and retrosplenial (RSC) cortices are active during self-referential decision-making tasks such as when participants appraise traits and abilities, or current affect. Other appraisal tasks requiring an evaluative decision or mental representation, such as theory of mind and perspective-taking tasks, also involve these regions. In many instances, these types of decisions involve a subjective opinion or preference, but also a degree of ambiguity in the decision, rather than a strictly veridical response. However, this ambiguity is generally not controlled for in studies that examine self-referential decision-making. In this functional magnetic resonance imaging experiment with 17 healthy …
The Neural Mechanisms Of Speech Comprehension: Fmri Studies Of Semantic Ambiguity, Jennifer M Rodd, Matthew H Davis, Ingrid Johnsrude
The Neural Mechanisms Of Speech Comprehension: Fmri Studies Of Semantic Ambiguity, Jennifer M Rodd, Matthew H Davis, Ingrid Johnsrude
Brain and Mind Institute Researchers' Publications
A number of regions of the temporal and frontal lobes are known to be important for spoken language comprehension, yet we do not have a clear understanding of their functional role(s). In particular, there is considerable disagreement about which brain regions are involved in the semantic aspects of comprehension. Two functional magnetic resonance studies use the phenomenon of semantic ambiguity to identify regions within the fronto-temporal language network that subserve the semantic aspects of spoken language comprehension. Volunteers heard sentences containing ambiguous words (e.g. 'the shell was fired towards the tank') and well-matched low-ambiguity sentences (e.g. 'her secrets were written …
Glutamate Receptors In Perirhinal Cortex Mediate Encoding, Retrieval, And Consolidation Of Object Recognition Memory., Boyer D Winters, Timothy J Bussey
Glutamate Receptors In Perirhinal Cortex Mediate Encoding, Retrieval, And Consolidation Of Object Recognition Memory., Boyer D Winters, Timothy J Bussey
Brain and Mind Institute Researchers' Publications
Object recognition is consistently impaired in human amnesia and animal models thereof. Results from subjects with permanent brain damage have revealed the importance of the perirhinal cortex to object recognition memory. Here, we report evidence from rats for interdependent but distinct stages in object recognition memory (encoding, retrieval, and consolidation), which require glutamate receptor activity within perirhinal cortex. Transient blockade of AMPA receptor-mediated synaptic transmission within perirhinal cortex disrupted encoding for short- and long-term memory as well as retrieval and consolidation. In contrast, transient NMDA receptor blockade during encoding affected only long-term object recognition memory; NMDA receptor activity was also …
Learning To Like: A Role For Human Orbitofrontal Cortex In Conditioned Reward, Sylvia M L Cox, Alexandre Andrade, Ingrid Johnsrude
Learning To Like: A Role For Human Orbitofrontal Cortex In Conditioned Reward, Sylvia M L Cox, Alexandre Andrade, Ingrid Johnsrude
Brain and Mind Institute Researchers' Publications
A great deal of human behavior and motivation is based on the intrinsic emotional significance of rewarding or aversive events, as well as on the associations formed between such emotional events and concurrent environmental stimuli. Recent functional neuroimaging studies have implicated the ventral striatum, orbitofrontal cortex (OFC), and amygdala in the representation of reward values and/or in the anticipation of rewarding events. Here, we use functional magnetic resonance imaging to compare brain activation during the presentation of reward with that during presentation of (conditioned) stimuli that have been paired previously with reward. Specifically, we aimed to investigate conditioned reward in …
A Contralateral Preference In The Lateral Occipital Area: Sensory And Attentional Mechanisms., Matthias Niemeier, Herbert C Goltz, Anil Kuchinad, Douglas B Tweed, Tutis Vilis
A Contralateral Preference In The Lateral Occipital Area: Sensory And Attentional Mechanisms., Matthias Niemeier, Herbert C Goltz, Anil Kuchinad, Douglas B Tweed, Tutis Vilis
Brain and Mind Institute Researchers' Publications
Here we examined the level of the lateral occipital (LO) area within the processing stream of the ventral visual cortex. An important determinant of an area's level of processing is whether it codes visual elements on both sides of the visual field, as do higher visual areas, or prefers those in the contralateral visual field, as do early visual areas. The former would suggest that LO, on one side, combines bilateral visual elements into a whole, while the latter suggests that it codes only the parts of forms. We showed that LO has a relative preference for visual objects in …
Transient Inactivation Of Perirhinal Cortex Disrupts Encoding, Retrieval, And Consolidation Of Object Recognition Memory., Boyer D Winters, Timothy J Bussey
Transient Inactivation Of Perirhinal Cortex Disrupts Encoding, Retrieval, And Consolidation Of Object Recognition Memory., Boyer D Winters, Timothy J Bussey
Brain and Mind Institute Researchers' Publications
Damage to perirhinal cortex (PRh) impairs object recognition memory in humans, monkeys, and rats when tested in tasks such as delayed nonmatching to sample, visual paired comparison, and its rodent analog, the spontaneous object recognition task. In the present study, we have capitalized on the discrete one-trial nature of the spontaneous object recognition task to investigate the role of PRh in several distinct stages of object recognition memory. In a series of experiments, transient inactivation of PRh was accomplished with bilateral infusions of lidocaine directly into PRh immediately before the sample phase (encoding), immediately before the choice phase (retrieval), or …