Open Access. Powered by Scholars. Published by Universities.®
- Publication Year
- Publication
- Publication Type
- File Type
Articles 31 - 53 of 53
Full-Text Articles in Neurosciences
Striatum In Stimulus-Response Learning Via Feedback And In Decision Making., Nole M Hiebert, Andrew Vo, Adam Hampshire, Adrian M Owen, Ken N Seergobin, Penny A Macdonald
Striatum In Stimulus-Response Learning Via Feedback And In Decision Making., Nole M Hiebert, Andrew Vo, Adam Hampshire, Adrian M Owen, Ken N Seergobin, Penny A Macdonald
Brain and Mind Institute Researchers' Publications
Cognitive deficits are recognized in Parkinson's disease. Understanding cognitive functions mediated by the striatum can clarify some of these impairments and inform treatment strategies. The dorsal striatum, a region impaired in Parkinson's disease, has been implicated in stimulus-response learning. However, most investigations combine acquisition of associations between stimuli, responses, or outcomes (i.e., learning) and expression of learning through response selection and decision enactment, confounding these separate processes. Using neuroimaging, we provide evidence that dorsal striatum does not mediate stimulus-response learning from feedback but rather underlies decision making once associations between stimuli and responses are learned. In the experiment, 11 males …
Mirror Reversal And Visual Rotation Are Learned And Consolidated Via Separate Mechanisms: Recalibrating Or Learning De Novo?, Sebastian Telgen, Darius Parvin, Jörn Diedrichsen
Mirror Reversal And Visual Rotation Are Learned And Consolidated Via Separate Mechanisms: Recalibrating Or Learning De Novo?, Sebastian Telgen, Darius Parvin, Jörn Diedrichsen
Brain and Mind Institute Researchers' Publications
Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored …
Continuous Executive Function Disruption Interferes With Application Of An Information Integration Categorization Strategy., Sarah J Miles, Kazunaga Matsuki, John Paul Minda
Continuous Executive Function Disruption Interferes With Application Of An Information Integration Categorization Strategy., Sarah J Miles, Kazunaga Matsuki, John Paul Minda
Brain and Mind Institute Researchers' Publications
Category learning is often characterized as being supported by two separate learning systems. A verbal system learns rule-defined (RD) categories that can be described using a verbal rule and relies on executive functions (EFs) to learn via hypothesis testing. A nonverbal system learns non-rule-defined (NRD) categories that cannot be described by a verbal rule and uses automatic, procedural learning. The verbal system is dominant in that adults tend to use it during initial learning but may switch to the nonverbal system when the verbal system is unsuccessful. The nonverbal system has traditionally been thought to operate independently of EFs, but …
Effector-Independent Motor Sequence Representations Exist In Extrinsic And Intrinsic Reference Frames., Tobias Wiestler, Sheena Waters-Metenier, Jörn Diedrichsen
Effector-Independent Motor Sequence Representations Exist In Extrinsic And Intrinsic Reference Frames., Tobias Wiestler, Sheena Waters-Metenier, Jörn Diedrichsen
Brain and Mind Institute Researchers' Publications
Many daily activities rely on the ability to produce meaningful sequences of movements. Motor sequences can be learned in an effector-specific fashion (such that benefits of training are restricted to the trained hand) or an effector-independent manner (meaning that learning also facilitates performance with the untrained hand). Effector-independent knowledge can be represented in extrinsic/world-centered or in intrinsic/body-centered coordinates. Here, we used functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis to determine the distribution of intrinsic and extrinsic finger sequence representations across the human neocortex. Participants practiced four sequences with one hand for 4 d, and then performed these sequences …
Bihemispheric Transcranial Direct Current Stimulation Enhances Effector-Independent Representations Of Motor Synergy And Sequence Learning., Sheena Waters-Metenier, Masud Husain, Tobias Wiestler, Jörn Diedrichsen
Bihemispheric Transcranial Direct Current Stimulation Enhances Effector-Independent Representations Of Motor Synergy And Sequence Learning., Sheena Waters-Metenier, Masud Husain, Tobias Wiestler, Jörn Diedrichsen
Brain and Mind Institute Researchers' Publications
Complex manual tasks-everything from buttoning up a shirt to playing the piano-fundamentally involve two components: (1) generating specific patterns of muscle activity (here, termed "synergies"); and (2) stringing these into purposeful sequences. Although transcranial direct current stimulation (tDCS) of the primary motor cortex (M1) has been found to increase the learning of motor sequences, it is unknown whether it can similarly facilitate motor synergy learning. Here, we determined the effects of tDCS on the learning of motor synergies using a novel hand configuration task that required the production of difficult muscular activation patterns. Bihemispheric tDCS was applied to M1 of …
A Multivariate Method To Determine The Dimensionality Of Neural Representation From Population Activity., Jörn Diedrichsen, Tobias Wiestler, Naveed Ejaz
A Multivariate Method To Determine The Dimensionality Of Neural Representation From Population Activity., Jörn Diedrichsen, Tobias Wiestler, Naveed Ejaz
Brain and Mind Institute Researchers' Publications
How do populations of neurons represent a variable of interest? The notion of feature spaces is a useful concept to approach this question: According to this model, the activation patterns across a neuronal population are composed of different pattern components. The strength of each of these components varies with one latent feature, which together are the dimensions along which the population represents the variable. Here we propose a new method to determine the number of feature dimensions that best describes the activation patterns. The method is based on Gaussian linear classifiers that use only the first d most important pattern …
Two Distinct Ipsilateral Cortical Representations For Individuated Finger Movements., Jörn Diedrichsen, Tobias Wiestler, John W Krakauer
Two Distinct Ipsilateral Cortical Representations For Individuated Finger Movements., Jörn Diedrichsen, Tobias Wiestler, John W Krakauer
Brain and Mind Institute Researchers' Publications
Movements of the upper limb are controlled mostly through the contralateral hemisphere. Although overall activity changes in the ipsilateral motor cortex have been reported, their functional significance remains unclear. Using human functional imaging, we analyzed neural finger representations by studying differences in fine-grained activation patterns for single isometric finger presses. We demonstrate that cortical motor areas encode ipsilateral movements in 2 fundamentally different ways. During unimanual ipsilateral finger presses, primary sensory and motor cortices show, underneath global suppression, finger-specific activity patterns that are nearly identical to those elicited by contralateral mirror-symmetric action. This component vanishes when both motor cortices are …
Decoding The Neural Mechanisms Of Human Tool Use., Jason P Gallivan, D Adam Mclean, Kenneth F Valyear, Jody C Culham
Decoding The Neural Mechanisms Of Human Tool Use., Jason P Gallivan, D Adam Mclean, Kenneth F Valyear, Jody C Culham
Brain and Mind Institute Researchers' Publications
Sophisticated tool use is a defining characteristic of the primate species but how is it supported by the brain, particularly the human brain? Here we show, using functional MRI and pattern classification methods, that tool use is subserved by multiple distributed action-centred neural representations that are both shared with and distinct from those of the hand. In areas of frontoparietal cortex we found a common representation for planned hand- and tool-related actions. In contrast, in parietal and occipitotemporal regions implicated in hand actions and body perception we found that coding remained selectively linked to upcoming actions of the hand whereas …
The Human Brain Processes Syntax In The Absence Of Conscious Awareness., Laura Batterink, Helen J Neville
The Human Brain Processes Syntax In The Absence Of Conscious Awareness., Laura Batterink, Helen J Neville
Brain and Mind Institute Researchers' Publications
Syntax is the core computational component of language. A longstanding idea about syntactic processing is that it is generally not available to conscious access, operating autonomously and automatically. However, there is little direct neurocognitive evidence on this issue. By measuring event-related potentials while human observers performed a novel cross-modal distraction task, we demonstrated that syntactic violations that were not consciously detected nonetheless produced a characteristic early neural response pattern, and also significantly delayed reaction times to a concurrent task. This early neural response was distinct from later neural activity that was observed only to syntactic violations that were consciously detected. …
Expanding The Basic Science Debate: The Role Of Physics Knowledge In Interpreting Clinical Findings., Mark Goldszmidt, John Paul Minda, Sarah L Devantier, Aimee L Skye, Nicole N Woods
Expanding The Basic Science Debate: The Role Of Physics Knowledge In Interpreting Clinical Findings., Mark Goldszmidt, John Paul Minda, Sarah L Devantier, Aimee L Skye, Nicole N Woods
Brain and Mind Institute Researchers' Publications
Current research suggests a role for biomedical knowledge in learning and retaining concepts related to medical diagnosis. However, learning may be influenced by other, non-biomedical knowledge. We explored this idea using an experimental design and examined the effects of causal knowledge on the learning, retention, and interpretation of medical information. Participants studied a handout about several respiratory disorders and how to interpret respiratory exam findings. The control group received the information in standard "textbook" format and the experimental group was presented with the same information as well as a causal explanation about how sound travels through lungs in both the …
Perceptual Fluency Can Be Used As A Cue For Categorization Decisions., Sarah J Miles, John Paul Minda
Perceptual Fluency Can Be Used As A Cue For Categorization Decisions., Sarah J Miles, John Paul Minda
Brain and Mind Institute Researchers' Publications
Learning in the prototype distortion task is thought to involve perceptual learning in which category members experience an enhanced visual response (Ashby & Maddox. Annual Review of Psychology, 56, 149-178, 2005). This response likely leads to more-efficient processing, which in turn may result in a feeling of perceptual fluency for category members. We examined the perceptual-fluency hypothesis by manipulating fluency independently from category membership. We predicted that when perceptual fluency was induced using subliminal priming, this fluency would be misattributed to category membership and would affect categorization decisions. In a prototype distortion task, the participants were more likely to judge …
Greater Benefits Of Multisensory Integration During Complex Sensorimotor Transformations., Verena N Buchholz, Samanthi C Goonetilleke, W Pieter Medendorp, Brian D Corneil
Greater Benefits Of Multisensory Integration During Complex Sensorimotor Transformations., Verena N Buchholz, Samanthi C Goonetilleke, W Pieter Medendorp, Brian D Corneil
Brain and Mind Institute Researchers' Publications
Multisensory integration enables rapid and accurate behavior. To orient in space, sensory information registered initially in different reference frames has to be integrated with the current postural information to produce an appropriate motor response. In some postures, multisensory integration requires convergence of sensory evidence across hemispheres, which would presumably lessen or hinder integration. Here, we examined orienting gaze shifts in humans to visual, tactile, or visuotactile stimuli when the hands were either in a default uncrossed posture or a crossed posture requiring convergence across hemispheres. Surprisingly, we observed the greatest benefits of multisensory integration in the crossed posture, as indexed …
Encoding Of Sensory Prediction Errors In The Human Cerebellum., John Schlerf, Richard B Ivry, Jörn Diedrichsen
Encoding Of Sensory Prediction Errors In The Human Cerebellum., John Schlerf, Richard B Ivry, Jörn Diedrichsen
Brain and Mind Institute Researchers' Publications
A central tenet of motor neuroscience is that the cerebellum learns from sensory prediction errors. Surprisingly, neuroimaging studies have not revealed definitive signatures of error processing in the cerebellum. Furthermore, neurophysiologic studies suggest an asymmetry, such that the cerebellum may encode errors arising from unexpected sensory events, but not errors reflecting the omission of expected stimuli. We conducted an imaging study to compare the cerebellar response to these two types of errors. Participants made fast out-and-back reaching movements, aiming either for an object that delivered a force pulse if intersected or for a gap between two objects, either of which …
Discriminating Famous From Fictional Names Based On Lifetime Experience: Evidence In Support Of A Signal-Detection Model Based On Finite Mixture Distributions., Ben Bowles, Iain M Harlow, Melissa M Meeking, Stefan Köhler
Discriminating Famous From Fictional Names Based On Lifetime Experience: Evidence In Support Of A Signal-Detection Model Based On Finite Mixture Distributions., Ben Bowles, Iain M Harlow, Melissa M Meeking, Stefan Köhler
Brain and Mind Institute Researchers' Publications
It is widely accepted that signal-detection mechanisms contribute to item-recognition memory decisions that involve discriminations between targets and lures based on a controlled laboratory study episode. Here, the authors employed mathematical modeling of receiver operating characteristics (ROC) to determine whether and how a signal-detection mechanism contributes to discriminations between moderately famous and fictional names based on lifetime experience. Unique to fame judgments is a lack of control over participants' previous exposure to the stimuli deemed "targets" by the experimenter; specifically, if they pertain to moderately famous individuals, participants may have had no prior exposure to a substantial proportion of the …
The Role Of Vision In Detecting And Correcting Fingertip Force Errors During Object Lifting, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale
The Role Of Vision In Detecting And Correcting Fingertip Force Errors During Object Lifting, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale
Gavin Buckingham
Vision provides many reliable cues about the likely weight of an object, allowing individuals to predict how heavy it will be. The forces used to lift an object for the first time reflect these predictions. This, however, leads to inevitable errors during lifts of objects that weigh unexpected amounts. Fortunately, these errors are rarely made twice in a row-lifters have the impressive ability to detect and correct large or small misapplications of fingertip forces, even while experiencing weight illusions. Although it has been assumed that we detect and correct these errors exclusively with our sense of touch, recent evidence has …
The Material-Weight Illusion Induced By Expectations Alone, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale
The Material-Weight Illusion Induced By Expectations Alone, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale
Gavin Buckingham
In the material-weight illusion (MWI), equally weighted objects that appear to be made from different materials are incorrectly perceived as having different weights when they are lifted one after the other. Here, we show that continuous visual experience of the lift is not a prerequisite for this compelling misperception of weight; merely priming the lifters' expectations of heaviness is sufficient for them to experience a robust MWI. Furthermore, these expectations continued to influence the load force used to lift MWI-inducing stimuli trial after trial, supporting the notion that vision plays an important role in the skillful lifting of objects.
The Influence Of Competing Perceptual And Motor Priors In The Context Of The Size-Weight Illusion, Gavin Buckingham, Melvyn Goodale
The Influence Of Competing Perceptual And Motor Priors In The Context Of The Size-Weight Illusion, Gavin Buckingham, Melvyn Goodale
Gavin Buckingham
When lifting objects of identical mass but different sizes, people perceive the smaller objects as weighing more than the larger ones (the 'size-weight' illusion, SWI). While individual's grip and load force rates are rapidly scaled to the objects' actual mass, the magnitude of the force used to lift these SWI-inducing objects is rarely discussed. Here, we show that participants continue to apply a greater loading force to a large SWI-inducing cube than to a small SWI cube, lift after lift. These differences in load force persisted long after initial errors in grip and load force rates had been corrected. Interestingly, …
Multiple Mechanisms Of Consciousness: The Neural Correlates Of Emotional Awareness., Jayna M Amting, Steven G Greening, Derek G V Mitchell
Multiple Mechanisms Of Consciousness: The Neural Correlates Of Emotional Awareness., Jayna M Amting, Steven G Greening, Derek G V Mitchell
Brain and Mind Institute Researchers' Publications
Emotional stimuli, including facial expressions, are thought to gain rapid and privileged access to processing resources in the brain. Despite this access, we are conscious of only a fraction of the myriad of emotion-related cues we face everyday. It remains unclear, therefore, what the relationship is between activity in neural regions associated with emotional representation and the phenomenological experience of emotional awareness. We used functional magnetic resonance imaging and binocular rivalry to delineate the neural correlates of awareness of conflicting emotional expressions in humans. Behaviorally, fearful faces were significantly more likely to be perceived than disgusted or neutral faces. Functionally, …
Gating Of Vibrotactile Detection During Visually Guided Bimanual Reaches, Gavin Buckingham, David Carey, Francisco Colino, John Degrosbois, Gordon Binsted
Gating Of Vibrotactile Detection During Visually Guided Bimanual Reaches, Gavin Buckingham, David Carey, Francisco Colino, John Degrosbois, Gordon Binsted
Gavin Buckingham
It is far more difficult to detect a small tactile stimulation on a finger that is moving compared to when it is static. This suppression of tactile information during motion, known as tactile gating, has been examined in some detail during single-joint movements. However, the existence and time course of this gating has yet to be examined during visually guided multi-joint reaches, where sensory feedback may be paramount. The current study demonstrated that neurologically intact humans are unable to detect a small vibratory stimulus on one of their index fingers during a bimanual reach toward visual targets. By parametrically altering …
Living In A Material World: How Visual Cues To Material Properties Affect The Way That We Lift Objects And Perceive Their Weight, Gavin Buckingham, Jonathan Cant, Melvyn Goodale
Living In A Material World: How Visual Cues To Material Properties Affect The Way That We Lift Objects And Perceive Their Weight, Gavin Buckingham, Jonathan Cant, Melvyn Goodale
Gavin Buckingham
The visual properties of an object provide many cues as to the tensile strength, compliance, and density of the material from which it is made. However, it is not well understood how these implicit associations affect our perceptions of these properties and how they determine the initial forces that are applied when an object is picked up. Here we examine the effects of these cues on such forces by using the classic "material-weight illusion" (MWI). Grip and load forces were measured in three experiments as participants lifted cubes made from metal, wood, and expanded polystyrene. These cubes were adjusted to …
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 …
Rightward Biases During Bimanual Reaching, Gavin Buckingham, David Carey
Rightward Biases During Bimanual Reaching, Gavin Buckingham, David Carey
Gavin Buckingham
Two experiments were carried out to investigate whether attention is biased toward the right hand of right handers during bimanual coordination (Peters 1981). A novel discontinuous double-step reaching task was developed, where right-handed participants executed a bimanual reach followed by a left or right hand unimanual reach. Asymmetries in the downtime between the bimanual and unimanual reach portions (the refractory period) were used to infer the direction of attention. A shorter right hand refractory period was found in the first experiment, indicating a rightward bias in attention. In a second experiment, shifting the focus of attention during the bimanual portion …