Medical Sciences Commons^™

Variational Representational Similarity Analysis, Karl J. Friston, Jörn Diedrichsen, Emma Holmes, Peter Zeidman

Brain and Mind Institute Researchers' Publications

© 2019 The Authors This technical note describes a variational or Bayesian implementation of representational similarity analysis (RSA) and pattern component modelling (PCM). It considers RSA and PCM as Bayesian model comparison procedures that assess the evidence for stimulus or condition-specific patterns of responses distributed over voxels or channels. On this view, one can use standard variational inference procedures to quantify the contributions of particular patterns to the data, by evaluating second-order parameters or hyperparameters. Crucially, this allows one to use parametric empirical Bayes (PEB) to infer which patterns are consistent among subjects. At the between-subject level, one can then …

Using Spatial Release From Masking To Estimate The Magnitude Of The Familiar-Voice Intelligibility Benefit, Ysabel Domingo, Emma Holmes, Ewan Macpherson, Ingrid S. Johnsrude

Brain and Mind Institute Researchers' Publications

© 2019 Acoustical Society of America. The ability to segregate simultaneous speech streams is crucial for successful communication. Recent studies have demonstrated that participants can report 10%-20% more words spoken by naturally familiar (e.g., friends or spouses) than unfamiliar talkers in two-voice mixtures. This benefit is commensurate with one of the largest benefits to speech intelligibility currently known - that which is gained by spatially separating two talkers. However, because of differences in the methods of these previous studies, the relative benefits of spatial separation and voice familiarity are unclear. Here, the familiar-voice benefit and spatial release from masking are …

A Sound-Sensitive Source Of Alpha Oscillations In Human Non-Primary Auditory Cortex, Alexander J. Billig, Björn Herrmann, Ariane E. Rhone, Phillip E. Gander, Kirill V. Nourski, Beau F. Snoad, Christopher K. Kovach, Hiroto Kawasaki, Matthew A. Howard, Ingrid S. Johnsrude

Brain and Mind Institute Researchers' Publications

Copyright © 2019 Billig, Herrmann et al. The functional organization of human auditory cortex can be probed by characterizing responses to various classes of sound at different anatomical locations. Along with histological studies this approach has revealed a primary field in posteromedial Heschl's gyrus (HG) with pronounced induced high-frequency (70-150 Hz) activity and short-latency responses that phase-lock to rapid transient sounds. Low-frequency neural oscillations are also relevant to stimulus processing and information flow, however, their distribution within auditory cortex has not been established. Alpha activity (7-14 Hz) in particular has been associated with processes that may differentially engage earlier versus …

An Accurate Registration Of The Bigbrain Dataset With The Mni Pd25 And Icbm152 Atlases., Yiming Xiao, Jonathan C Lau, Taylor Anderson, Jordan Dekraker, D Louis Collins, Terry Peters, Ali R Khan

Brain and Mind Institute Researchers' Publications

Brain atlases that encompass detailed anatomical or physiological features are instrumental in the research and surgical planning of various neurological conditions. Magnetic resonance imaging (MRI) has played important roles in neuro-image analysis while histological data remain crucial as a gold standard to guide and validate such analyses. With cellular-scale resolution, the BigBrain atlas offers 3D histology of a complete human brain, and is highly valuable to the research and clinical community. To bridge the insights at macro- and micro-levels, accurate mapping of BigBrain and established MRI brain atlases is necessary, but the existing registration is unsatisfactory. The described dataset includes …

A Framework For Evaluating Correspondence Between Brain Images Using Anatomical Fiducials., Jonathan C Lau, Andrew G Parrent, John Demarco, Geetika Gupta, Jason Kai, Olivia W Stanley, Tristan Kuehn, Patrick J Park, Kayla Ferko, Ali R Khan, Terry M Peters

Brain and Mind Institute Researchers' Publications

Accurate spatial correspondence between template and subject images is a crucial step in neuroimaging studies and clinical applications like stereotactic neurosurgery. In the absence of a robust quantitative approach, we sought to propose and validate a set of point landmarks, anatomical fiducials (AFIDs), that could be quickly, accurately, and reliably placed on magnetic resonance images of the human brain. Using several publicly available brain templates and individual participant datasets, novice users could be trained to place a set of 32 AFIDs with millimetric accuracy. Furthermore, the utility of the AFIDs protocol is demonstrated for evaluating subject-to-template and template-to-template registration. Specifically, …

Stimulus-Locked Responses On Human Upper Limb Muscles And Corrective Reaches Are Preferentially Evoked By Low Spatial Frequencies, Rebecca A. Kozak, Philipp Kreyenmeier, Chao Gu, Kevin Johnston, Brian D. Corneil

Brain and Mind Institute Researchers' Publications

© 2019 Kozak et al. In situations requiring immediate action, humans can generate visually-guided responses at remarkably short latencies. Here, to better understand the visual attributes that best evoke such rapid responses, we recorded upper limb muscle activity while participants performed visually-guided reaches towards Gabor patches composed of differing spatial frequencies (SFs). We studied reaches initiated from a stable posture (experiment 1, a static condition), or during on-line reach corrections to an abruptly displaced target (experiment 2, a dynamic condition). In both experiments, we detail the latency and prevalence of stimulus-locked responses (SLRs), which are brief bursts of EMG activity …

Thirty-Five Years Of Computerized Cognitive Assessment Of Aging — Where Are We Now?, Avital Sternin, Alistair Burns, Adrian M. Owen

Brain and Mind Institute Researchers' Publications

Over the past 35 years, the proliferation of technology and the advent of the internet have resulted in many reliable and easy to administer batteries for assessing cognitive function. These approaches have great potential for affecting how the health care system monitors and screens for cognitive changes in the aging population. Here, we review these new technologies with a specific emphasis on what they offer over and above traditional ‘paper-and-pencil’ approaches to assessing cognitive function. Key advantages include fully automated administration and scoring, the interpretation of individual scores within the context of thousands of normative data points, the inclusion of …

Binding During Sequence Learning Does Not Alter Cortical Representations Of Individual Actions, Patrick Beukema, Jörn Diedrichsen, Timothy D. Verstynen

Brain and Mind Institute Researchers' Publications

Copyright © 2019 the authors. As a sequence of movements is learned, serially ordered actions get bound together into sets to reduce computational complexity during planning and execution. Here, we investigated how actions become naturally bound over the course of learning and how this learning affects cortical representations of individual actions. Across 5 weeks of practice, neurologically healthy human subjects learned either a complex 32-item sequence of finger movements (trained group, n = 9; 3 female) or randomly ordered actions (control group, n = 9; 3 female). Over the course of practice, responses during sequence production in the trained group …

Cortical Beta Oscillations Are Associated With Motor Performance Following Visuomotor Learning, Svenja Espenhahn, Bernadette C.M. Van Wijk, Holly E. Rossiter, Archy O. De Berker, Nell D. Redman, Jane Rondina, Joern Diedrichsen, Nick S. Ward

Brain and Mind Institute Researchers' Publications

© 2019 The Authors People vary in their capacity to learn and retain new motor skills. Although the relationship between neuronal oscillations in the beta frequency range (15–30 Hz) and motor behaviour is well established, the electrophysiological mechanisms underlying individual differences in motor learning are incompletely understood. Here, we investigated the degree to which measures of resting and movement-related beta power from sensorimotor cortex account for inter-individual differences in motor learning behaviour in the young and elderly. Twenty young (18–30 years) and twenty elderly (62–77 years) healthy adults were trained on a novel wrist flexion/extension tracking task and subsequently retested …

Glucocorticoids And “Stress” Are Not Synonymous, Scott Macdougall-Shackleton

Brain and Mind Institute Researchers' Publications

Synopsis

Reference to glucocorticoids as “stress hormones” has been growing in prevalence in the literature, including in comparative and environmental endocrinology. Although glucocorticoids are elevated in response to a variety of stressors in vertebrate animals, the primary functions of glucocorticoids are not responding to stressors and they are only one component of complex suite of physiological and behavioral responses to stressors. Thus, the use of the short-hand phrase “stress hormone” can be misleading. Further, simply measuring glucocorticoids is not equivalent to measuring a stress response, nor is manipulating glucocorticoids equivalent to exposing an animal to a stressor. In this commentary …

Understanding The Neural Bases Of Implicit And Statistical Learning, Laura J. Batterink, Ken A. Paller, Paul J. Reber

Brain and Mind Institute Researchers' Publications

© 2019 Cognitive Science Society, Inc. Both implicit learning and statistical learning focus on the ability of learners to pick up on patterns in the environment. It has been suggested that these two lines of research may be combined into a single construct of “implicit statistical learning.” However, by comparing the neural processes that give rise to implicit versus statistical learning, we may determine the extent to which these two learning paradigms do indeed describe the same core mechanisms. In this review, we describe current knowledge about neural mechanisms underlying both implicit learning and statistical learning, highlighting converging findings between …

Macaque Anterior Cingulate Cortex Deactivation Impairs Performance And Alters Lateral Prefrontal Oscillatory Activities In A Rule-Switching Task, Liya Ma, Jason L. Chan, Kevin Johnston, Stephen G. Lomber, Stefan Everling

Brain and Mind Institute Researchers' Publications

© 2019 Ma et al. In primates, both the dorsal anterior cingulate cortex (dACC) and the dorsolateral prefrontal cortex (dlPFC) are key regions of the frontoparietal cognitive control network. To study the role of the dACC and its communication with the dlPFC in cognitive control, we recorded local field potentials (LFPs) from the dlPFC before and during the reversible deactivation of the dACC, in macaque monkeys engaging in uncued switches between 2 stimulus-response rules, namely prosaccade and antisaccade. Cryogenic dACC deactivation impaired response accuracy during maintenance of—but not the initial switching to—the cognitively demanding antisaccade rule, which coincided with a …

The Neural Association Between Arithmetic And Basic Numerical Processing Depends On Arithmetic Problem Size And Not Chronological Age, Anna A. Matejko, Daniel Ansari

Brain and Mind Institute Researchers' Publications

© 2019 The Authors The intraparietal sulcus (IPS) is thought to be an important region for basic number processing (e.g. symbol-quantity associations) and arithmetic (e.g. addition). Evidence for shared circuitry within the IPS is largely based on comparisons across studies, and little research has investigated number processing and arithmetic in the same individuals. It is also unclear how the neural overlap between number processing and arithmetic is influenced by age and arithmetic problem difficulty. This study investigated these unresolved questions by examining basic number processing (symbol-quantity matching) and arithmetic (addition) networks in 26 adults and 42 children. Number processing and …

Resonate: Reflections And Recommendations On Implicit Biases Within The Ismrm, Esther A.H. Warnert, Krishna Nayak, Ravi Menon, Curt Rice, John Port, Elizabeth A. Morris, Daniel K. Sodickson, Pia Sundgren, Karla L. Miller, Udunna C. Anazodo

Brain and Mind Institute Researchers' Publications

No abstract provided.

Simple Random-Interval Generation Reveals The Irresistibly Periodic Structure Of Perceived Time, Jessica A. Grahn, J. Eric Taylor

Brain and Mind Institute Researchers' Publications

Whole-integer ratios in musical rhythm are culturally universal. The reliable periodicity of rhythm inspired us to determine whether time perception, which is foundational to and inherently less structured than rhythm, is subject to similar biases. We created a random-interval generation task that exploits the nonrandom tendencies in perception and action in order to uncover the structural biases underlying temporal duration perception. Participants listened to and watched an audiovisual suprasecond temporal cue and were asked to subdivide it as randomly as possible in a prescribed number of responses. The results showed that the subdivision probability distributions were distinctly nonrandom, and closely …

A Consensus Guide To Capturing The Ability To Inhibit Actions And Impulsive Behaviors In The Stop-Signal Task., Frederick Verbruggen, Adam R Aron, Guido Ph Band, Christian Beste, Patrick G Bissett, Adam T Brockett, Joshua W Brown, Samuel R Chamberlain, Christopher D Chambers, Hans Colonius, Lorenza S Colzato, Brian D Corneil, James P Coxon, Annie Dupuis, Dawn M Eagle, Hugh Garavan, Ian Greenhouse, Andrew Heathcote, René J Huster, Sara Jahfari, J Leon Kenemans, Inge Leunissen, Chiang-Shan R Li, Gordon D Logan, Dora Matzke, Sharon Morein-Zamir, Aditya Murthy, Martin Paré, Russell A Poldrack, K Richard Ridderinkhof, Trevor W Robbins, Matthew Roesch, Katya Rubia, Russell J Schachar, Jeffrey D Schall, Ann-Kathrin Stock, Nicole C Swann, Katharine N Thakkar, Maurits W Van Der Molen, Luc Vermeylen, Matthijs Vink, Jan R Wessel, Robert Whelan, Bram B Zandbelt, C Nico Boehler

Brain and Mind Institute Researchers' Publications

Response inhibition is essential for navigating everyday life. Its derailment is considered integral to numerous neurological and psychiatric disorders, and more generally, to a wide range of behavioral and health problems. Response-inhibition efficiency furthermore correlates with treatment outcome in some of these conditions. The stop-signal task is an essential tool to determine how quickly response inhibition is implemented. Despite its apparent simplicity, there are many features (ranging from task design to data analysis) that vary across studies in ways that can easily compromise the validity of the obtained results. Our goal is to facilitate a more accurate use of the …

Assessment Of Mglur5 Ko Mice Under Conditions Of Low Stress Using A Rodent Touchscreen Apparatus Reveals Impaired Behavioural Flexibility Driven By Perseverative Responses, Jisoo Lim, Eosu Kim, Hyun Jong Noh, Shinwon Kang, Benjamin U. Phillips, Dong Goo Kim, Timothy J. Bussey, Lisa Saksida, Christopher J. Heath, Chul Hoon Kim

Brain and Mind Institute Researchers' Publications

© 2019 The Author(s). Genetic and pharmacological manipulations targeting metabotropic glutamate receptor 5 (mGluR5) affect performance in behavioural paradigms that depend on cognitive flexibility. Many of these studies involved exposing mice to highly stressful conditions including electric foot shocks or water immersion and forced swimming. Because mGluR5 is also implicated in resilience and stress responses, however, apparent impairments in inhibitory learning may have been an artifact of manipulation-induced changes in affective state. To address this, we present here a characterization of cognitive flexibility in mGluR5 knockout (KO) mice conducted with a rodent touchscreen cognitive assessment apparatus in which the animals …

Annual Research Review: Educational Neuroscience: Progress And Prospects, Michael S.C. Thomas, Daniel Ansari, Victoria C.P. Knowland

Brain and Mind Institute Researchers' Publications

© 2018 The Authors. Journal of Child Psychology and Psychiatry published by John Wiley & Sons Ltd on behalf of Association for Child and Adolescent Mental Health. Educational neuroscience is an interdisciplinary research field that seeks to translate research findings on neural mechanisms of learning to educational practice and policy and to understand the effects of education on the brain. Neuroscience and education can interact directly, by virtue of considering the brain as a biological organ that needs to be in the optimal condition to learn (‘brain health’); or indirectly, as neuroscience shapes psychological theory and psychology influences education. In …

A Consensus Guide To Capturing The Ability To Inhibit Actions And Impulsive Behaviors In The Stop-Signal Task, Frederick Verbruggen, Adam R. Aron, Guido P.H. Band, Christian Beste, Patrick G. Bissett, Adam T. Brockett, Joshua W. Brown, Samuel R. Chamberlain, Christopher D. Chambers, Hans Colonius, Lorenza S. Colzato, Brian D. Corneil, James P. Coxon, Annie Dupuis, Dawn M. Eagle, Hugh Garavan, Ian Greenhouse, Andrew Heathcote, Rene´ J. Huster, Sara Jahfari, J. Leon Kenemans, Inge Leunissen, Chiang Shan R. Li, Gordon D. Logan, Dora Matzke, Sharon Morein-Zamir, Aditya Murthy, Martin Paré, Russell A. Poldrack, K. Richard Ridderinkhof, Trevor W. Robbins, Matthew Roesch

Brain and Mind Institute Researchers' Publications

© Verbruggen et al. Response inhibition is essential for navigating everyday life. Its derailment is considered integral to numerous neurological and psychiatric disorders, and more generally, to a wide range of behavioral and health problems. Response-inhibition efficiency furthermore correlates with treatment outcome in some of these conditions. The stop-signal task is an essential tool to determine how quickly response inhibition is implemented. Despite its apparent simplicity, there are many features (ranging from task design to data analysis) that vary across studies in ways that can easily compromise the validity of the obtained results. Our goal is to facilitate a more …

Rethinking Interhemispheric Imbalance As A Target For Stroke Neurorehabilitation, Jing Xu, Meret Branscheidt, Heidi Schambra, Levke Steiner, Mario Widmer, Jörn Diedrichsen, Jeff Goldsmith, Martin Lindquist, Tomoko Kitago, Andreas R. Luft, John W. Krakauer, Pablo A. Celnik, Nathan Kim, Michelle D. Harran, Benjamin Hertler, Juan C. Cortes

Brain and Mind Institute Researchers' Publications

© 2019 American Neurological Association Objective: Patients with chronic stroke have been shown to have failure to release interhemispheric inhibition (IHI) from the intact to the damaged hemisphere before movement execution (premovement IHI). This inhibitory imbalance was found to correlate with poor motor performance in the chronic stage after stroke and has since become a target for therapeutic interventions. The logic of this approach, however, implies that abnormal premovement IHI is causal to poor behavioral outcome and should therefore be present early after stroke when motor impairment is at its worst. To test this idea, in a longitudinal study, we …

Spinal Stretch Reflexes Support Efficient Hand Control, Jeffrey Weiler, Paul L. Gribble, J. Andrew Pruszynski

Brain and Mind Institute Researchers' Publications

© 2019, The Author(s), under exclusive licence to Springer Nature America, Inc. Motor behaviour is most efficiently controlled by correcting only disturbances that influence task success. It is currently thought that such control is computed within a transcortical feedback pathway. Here we show that, for postural hand control, even the fastest spinal feedback pathway can produce efficient corrective responses, forcing a re-evaluation of how the nervous system derives the control laws that support motor behavior.

Feasibility Of A Web-Based Neurocognitive Battery For Assessing Cognitive Function In Critical Illness Survivors, Kimia Honarmand, Sabhyata Malik, Conor Wild, Laura E. Gonzalez-Lara, Christopher W. Mcintyre, Adrian M. Owen, Marat Slessarev

Brain and Mind Institute Researchers' Publications

Purpose To assess the feasibility of using a widely validated, web-based neurocognitive test battery (Cambridge Brain Sciences, CBS) in a cohort of critical illness survivors. Methods We conducted a prospective observational study in two intensive care units (ICUs) at two tertiary care hospitals. Twenty non-delirious ICU patients who were mechanically ventilated for a minimum of 24 hours underwent cognitive testing using the CBS battery. The CBS consists of 12 cognitive tests that assess a broad range of cognitive abilities that can be categorized into three cognitive domains: reasoning skills, short-term memory, and verbal processing. Patients underwent cognitive assessment while still …

The Material-Weight Illusion Disappears Or Inverts In Objects Made Of Two Materials, Vivian C. Paulun, Gavin Buckingham, Melvyn A. Goodale, Roland W. Fleming

Brain and Mind Institute Researchers' Publications

© the American Physiological Society. The material-weight illusion disappears or inverts in objects made of two materials. J Neurophysiol 121: 996 –1010, 2019. First published January 23, 2019; doi:10.1152/jn.00199.2018.—The material-weight illusion (MWI) occurs when an object that looks heavy (e.g., stone) and one that looks light (e.g., Styrofoam) have the same mass. When such stimuli are lifted, the heavier-looking object feels lighter than the lighter-looking object, presumably because well-learned priors about the density of different materials are violated. We examined whether a similar illusion occurs when a certain weight distribution is expected (such as the metal end of a hammer …

The Gradient Of The Reinforcement Landscape Influences Sensorimotor Learning, Joshua G.A. Cashaback, Christopher K. Lao, Dimitrios J. Palidis, Susan K. Coltman, Heather R. Mcgregor, Paul L. Gribble

Brain and Mind Institute Researchers' Publications

© 2019 Cashaback et al. Consideration of previous successes and failures is essential to mastering a motor skill. Much of what we know about how humans and animals learn from such reinforcement feedback comes from experiments that involve sampling from a small number of discrete actions. Yet, it is less understood how we learn through reinforcement feedback when sampling from a continuous set of possible actions. Navigating a continuous set of possible actions likely requires using gradient information to maximize success. Here we addressed how humans adapt the aim of their hand when experiencing reinforcement feedback that was associated with …

Understanding Perirhinal Contributions To Perception And Memory: Evidence Through The Lens Of Selective Perirhinal Damage, Marika C. Inhoff, Andrew C. Heusser, Arielle Tambini, Chris B. Martin, Edward B. O'Neil, Stefan Köhler, Michael R. Meager, Karen Blackmon, Blanca Vazquez, Orrin Devinsky, Lila Davachi

Brain and Mind Institute Researchers' Publications

© 2019 Elsevier Ltd Although a memory systems view of the medial temporal lobe (MTL) has been widely influential in understanding how memory processes are implemented, a large body of work across humans and animals has converged on the idea that the MTL can support various other decisions, beyond those involving memory. Specifically, recent work suggests that perception of and memory for visual representations may interact in order to support ongoing cognition. However, given considerations involving lesion profiles in neuropsychological investigations and the correlational nature of fMRI, the precise nature of representations supported by the MTL are not well understood …

Intrinsic Functional Boundaries Of Lateral Frontal Cortex In The Common Marmoset Monkey, David J. Schaeffer, Kyle M. Gilbert, Joseph S. Gati, Ravi S. Menon, Stefan Everling

Brain and Mind Institute Researchers' Publications

© 2019 the authors. The common marmoset (Callithrix jacchus) is a small New World primate species that has been recently targeted as a potentially powerful preclinical model of human prefrontal cortex dysfunction. Although the structural boundaries of frontal cortex were described in marmosets at the start of the 20th century (Brodmann, 1909) and refined more recently (Paxinos et al., 2012), the broad functional boundaries of marmoset frontal cortex have yet to be established. In this study, we sought to functionally derive boundaries of the marmoset lateral frontal cortex (LFC) using ultra-high field (9.4 T) resting-state functional magnetic resonance imaging (RS-fMRI). …

Human Consciousness Is Supported By Dynamic Complex Patterns Of Brain Signal Coordination, A. Demertzi, E. Tagliazucchi, S. Dehaene, G. Deco, P. Barttfeld, F. Raimondo, C. Martial, D. Fernández-Espejo, B. Rohaut, H. U. Voss, N. D. Schiff, A. M. Owen, S. Laureys, L. Naccache, J. D. Sitt

Brain and Mind Institute Researchers' Publications

Adopting the framework of brain dynamics as a cornerstone of human consciousness, we determined whether dynamic signal coordination provides specific and generalizable patterns pertaining to conscious and unconscious states after brain damage. A dynamic pattern of coordinated and anticoordinated functional magnetic resonance imaging signals characterized healthy individuals and minimally conscious patients. The brains of unresponsive patients showed primarily a pattern of low interareal phase coherence mainly mediated by structural connectivity, and had smaller chances to transition between patterns. The complex pattern was further corroborated in patients with covert cognition, who could perform neuroimaging mental imagery tasks, validating this pattern’s implication …

Obtaining And Maintaining Cortical Hand Representation As Evidenced From Acquired And Congenital Handlessness, Daan B. Wesselink, Fiona Mz Van Den Heiligenberg, Naveed Ejaz, Harriet Dempsey-Jones, Lucilla Cardinali, Aurelie Tarall-Jozwiak, Jörn Diedrichsen, Tamar R. Makin

Brain and Mind Institute Researchers' Publications

© Lukinova et al. A key question in neuroscience is how cortical organisation relates to experience. Previously we showed that amputees experiencing highly vivid phantom sensations maintain cortical representation of their missing hand (Kikkert et al., 2016). Here, we examined the role of sensory hand experience on persistent hand representation by studying individuals with acquired and congenital hand loss. We used representational similarity analysis in primary somatosensory and motor cortex during missing and intact hand movements. We found that key aspects of acquired amputees’ missing hand representation persisted, despite varying vividness of phantom sensations. In contrast, missing hand representation of …

Unmet Need For Mental Health Services Among People Screened But Not Admitted To An Early Psychosis Intervention Program, Jordan Edwards, Ross Norman, Paul Kurdyak, Arlene G. Macdougall, Lena Palaniyappan, Cindy Lau, Kelly K. Anderson

Brain and Mind Institute Researchers' Publications

Information is lacking on people screened for early psychosis intervention (EPI) but not admitted to the program. Using health administrative data, we constructed a retrospective cohort of incident cases of psychosis in the catchment of an EPI program. Use of mental health services was compared between people screened and not admitted with an EPI-admitted group. The non-admitted group had higher rates of subsequent emergency department visits, psychiatric hospitalizations, and involuntary admissions. These patterns are indicative of unmet need, and people screened but not admitted to EPI may benefit from protocols to improve transitions of care with other service providers.

Dorsal Striatum Does Not Mediate Feedback-Based, Stimulus-Response Learning: An Event-Related Fmri Study In Patients With Parkinson's Disease Tested On And Off Dopaminergic Therapy, Nole M. Hiebert, Adrian M. Owen, Hooman Ganjavi, Daniel Mendonça, Mary E. Jenkins, Ken N. Seergobin, Penny A. Macdonald

Brain and Mind Institute Researchers' Publications

© 2018 Learning associations between stimuli and responses is essential to everyday life. Dorsal striatum (DS) has long been implicated in stimulus-response learning, though recent results challenge this contention. We have proposed that discrepant findings arise because stimulus-response learning methodology generally confounds learning and response selection processes. In 19 patients with Parkinson's disease (PD) and 18 age-matched controls, we found that dopaminergic therapy decreased the efficiency of stimulus-response learning, with corresponding attenuation of ventral striatum (VS) activation. In contrast, exogenous dopamine improved response selection accuracy related to enhanced DS BOLD signal. Contrasts between PD patients and controls fully support these …