Neurosciences Commons^™

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 …

Developmental Stress, Condition, And Birdsong: A Case Study In Song Sparrows., Kim L Schmidt, Elizabeth A Macdougall-Shackleton, Shawn P Kubli, Scott A Macdougall-Shackleton

Brain and Mind Institute Researchers' Publications

Sexual-selection theory posits that ornaments and displays can reflect a signaler's condition, which in turn is affected both by recent and developmental conditions. Moreover, developmental conditions can induce correlations between sexually selected and other traits if both types of traits exhibit developmental phenotypic plasticity in response to stressors. Thus, sexually selected traits may reflect recent and/or developmental characteristics of signalers. Here, we review data on the relationships between birdsong, a sexually selected trait, and developmental and current condition of birds from a long-term study of a population of song sparrows (Melospiza melodia). Field studies of free-living birds indicate that the …

Sharp Emergence Of Feature-Selective Sustained Activity Along The Dorsal Visual Pathway., Diego Mendoza-Halliday, Santiago Torres, Julio C Martinez-Trujillo

Brain and Mind Institute Researchers' Publications

Sustained activity encoding visual working memory representations has been observed in several cortical areas of primates. Where along the visual pathways this activity emerges remains unknown. Here we show in macaques that sustained spiking activity encoding memorized visual motion directions is absent in direction-selective neurons in early visual area middle temporal (MT). However, it is robustly present immediately downstream, in multimodal association area medial superior temporal (MST), as well as and in the lateral prefrontal cortex (LPFC). This sharp emergence of sustained activity along the dorsal visual pathway suggests a functional boundary between early visual areas, which encode sensory inputs, …

Human Premotor Areas Parse Sequences Into Their Spatial And Temporal Features., Katja Kornysheva, Jörn Diedrichsen

Brain and Mind Institute Researchers' Publications

Skilled performance is characterized by precise and flexible control of movement sequences in space and time. Recent theories suggest that integrated spatio-temporal trajectories are generated by intrinsic dynamics of motor and premotor networks. This contrasts with behavioural advantages that emerge when a trained spatial or temporal feature of sequences is transferred to a new spatio-temporal combination arguing for independent neural representations of these sequence features. We used a new fMRI pattern classification approach to identify brain regions with independent vs integrated representations. A distinct regional dissociation within motor areas was revealed: whereas only the contralateral primary motor cortex exhibited unique …

Self-Injurious Behaviours Are Associated With Alterations In The Somatosensory System In Children With Autism Spectrum Disorder., Emma G Duerden, Dallas Card, S Wendy Roberts, Kathleen M Mak-Fan, M Mallar Chakravarty, Jason P Lerch, Margot J Taylor

Brain and Mind Institute Researchers' Publications

Children with autism spectrum disorder (ASD) frequently engage in self-injurious behaviours, often in the absence of reporting pain. Previous research suggests that altered pain sensitivity and repeated exposure to noxious stimuli are associated with morphological changes in somatosensory and limbic cortices. Further evidence from postmortem studies with self-injurious adults has indicated alterations in the structure and organization of the temporal lobes; however, the effect of self-injurious behaviour on cortical development in children with ASD has not yet been determined. Thirty children and adolescents (mean age = 10.6 ± 2.5 years; range 7-15 years; 29 males) with a clinical diagnosis of …

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

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 …

Investigating The Relation Between Striatal Volume And Iq., Penny A Macdonald, Hooman Ganjavi, D Louis Collins, Alan C Evans, Sherif Karama

Brain and Mind Institute Researchers' Publications

The volume of the input region of the basal ganglia, the striatum, is reduced with aging and in a number of conditions associated with cognitive impairment. The aim of the current study was to investigate the relation between the volume of striatum and general cognitive ability in a sample of 303 healthy children that were sampled to be representative of the population of the United States. Correlations between the WASI-IQ and the left striatum, composed of the caudate nucleus and putamen, were significant. When these data were analyzed separately for male and female children, positive correlations were significant for the …

Corticosterone Administration Up-Regulated Expression Of Norepinephrine Transporter And Dopamine Β-Hydroxylase In Rat Locus Coeruleus And Its Terminal Regions, Yan Fan, Ping Ping Chen, Ying Li, Kui Cui, Daniel M. Noel, Elizabeth D. Cummins, Daniel J. Peterson, Russell W. Brown, Meng-Yang Zhu

ETSU Faculty Works

Stress has been reported to activate the locus coeruleus (LC)-noradrenergic system. In this study, corticosterone (CORT) was orally administrated to rats for 21 days to mimic stress status. In situ hybridization measurements showed that CORT ingestion significantly increased mRNA levels of norepinephrine transporter (NET) and dopamine β-hydroxylase (DBH) in the LC region. Immunofluorescence staining and western blotting revealed that CORT treatment also increased protein levels of NET and DBH in the LC, as well as NET protein levels in the hippocampus, the frontal cortex and the amygdala. However, CORT-induced increase in DBH protein levels only appeared in the hippocampus and …

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 …

Bilateral Saccadic Deficits Following Large And Reversible Inactivation Of Unilateral Frontal Eye Field., Tyler R Peel, Kevin Johnston, Stephen G Lomber, Brian D Corneil

Brain and Mind Institute Researchers' Publications

Inactivation permits direct assessment of the functional contribution of a given brain area to behavior. Previous inactivation studies of the frontal eye field (FEF) have either used large permanent ablations or reversible pharmacological techniques that only inactivate a small volume of tissue. Here we evaluated the impact of large, yet reversible, FEF inactivation on visually guided, delayed, and memory-guided saccades, using cryoloops implanted in the arcuate sulcus. While FEF inactivation produced the expected triad of contralateral saccadic deficits (increased reaction time, decreased accuracy and peak velocity) and performance errors (neglect or misdirected saccades), we also found consistent increases in reaction …

Short-Duration Stimulation Of The Supplementary Eye Fields Perturbs Anti-Saccade Performance While Potentiating Contralateral Head Orienting., Brendan B Chapman, Brian D Corneil

Brain and Mind Institute Researchers' Publications

Many forms of brain stimulation utilize the notion of state dependency, whereby greater influences are observed when a given area is more engaged at the time of stimulation. Here, by delivering intracortical microstimulation (ICMS) to the supplementary eye fields (SEF) of monkeys performing interleaved pro- and anti-saccades, we show a surprising diversity of state-dependent effects of ICMS-SEF. Short-duration ICMS-SEF passed around cue presentation selectively disrupted anti-saccades by increasing reaction times and error rates bilaterally, and also recruited neck muscles, favoring contralateral head turning to a greater degree on anti-saccade trials. These results are consistent with the functional relevance of the …

Observing Object Lifting Errors Modulates Cortico-Spinal Excitability And Improves Object Lifting Performance., Gavin Buckingham, Jeremy D Wong, Minnie Tang, Paul L Gribble, Melvyn A Goodale

Brain and Mind Institute Researchers' Publications

Observing the actions of others has been shown to modulate cortico-spinal excitability and affect behaviour. However, the sensorimotor consequences of observing errors are not well understood. Here, participants watched actors lift identically weighted large and small cubes which typically elicit expectation-based fingertip force errors. One group of participants observed the standard overestimation and underestimation-style errors that characterise early lifts with these cubes (Error video--EV). Another group watched the same actors performing the well-adapted error-free lifts that characterise later, well-practiced lifts with these cubes (No error video--NEV). We then examined actual object lifting performance in the subjects who watched the EV …

Sign Language Ability In Young Deaf Signers Predicts Comprehension Of Written Sentences In English., Kathy N Andrew, Jennifer Hoshooley, Marc F Joanisse

Brain and Mind Institute Researchers' Publications

We investigated the robust correlation between American Sign Language (ASL) and English reading ability in 51 young deaf signers ages 7;3 to 19;0. Signers were divided into 'skilled' and 'less-skilled' signer groups based on their performance on three measures of ASL. We next assessed reading comprehension of four English sentence structures (actives, passives, pronouns, reflexive pronouns) using a sentence-to-picture-matching task. Of interest was the extent to which ASL proficiency provided a foundation for lexical and syntactic processes of English. Skilled signers outperformed less-skilled signers overall. Error analyses further indicated greater single-word recognition difficulties in less-skilled signers marked by a higher …

Rule-Based Category Learning In Children: The Role Of Age And Executive Functioning., Rahel Rabi, John Paul Minda

Brain and Mind Institute Researchers' Publications

Rule-based category learning was examined in 4-11 year-olds and adults. Participants were asked to learn a set of novel perceptual categories in a classification learning task. Categorization performance improved with age, with younger children showing the strongest rule-based deficit relative to older children and adults. Model-based analyses provided insight regarding the type of strategy being used to solve the categorization task, demonstrating that the use of the task appropriate strategy increased with age. When children and adults who identified the correct categorization rule were compared, the performance deficit was no longer evident. Executive functions were also measured. While both working …

An Anemia Of Alzheimer's Disease, N G. Faux, A Rembach, J Wiley, K A. Ellis, D Ames, C J. Fowler, Ralph N. Martins, K K. Pertile, R L. Rumble, B Trounson, C L. Masters, A I. Bush

Research outputs 2014 to 2021

Lower hemoglobin is associated with cognitive impairment and Alzheimer's disease (AD). Since brain iron homeostasis is perturbed in AD, we investigated whether this is peripherally reflected in the hematological and related blood chemistry values from the Australian Imaging Biomarker and Lifestyle (AIBL) study (a community-based, cross-sectional cohort comprising 768 healthy controls (HC), 133 participants with mild cognitive impairment (MCI) and 211 participants with AD). We found that individuals with AD had significantly lower hemoglobin, mean cell hemoglobin concentrations, packed cell volume and higher erythrocyte sedimentation rates (adjusted for age, gender, APOE-ε4 and site). In AD, plasma iron, transferrin, transferrin saturation …

Extending The Indications Of Flow Diversion To Small, Unruptured, Saccular Aneurysms Of The Anterior Circulation., Nohra Chalouhi, Md, Robert M Starke, Steven Yang, Cory D Bovenzi, Stavropoula Tjoumakaris, David Hasan, L. Fernando Gonzalez, Robert H. Rosenwasswer Md, Pascal Jabbour Md

Department of Neurosurgery Faculty Papers

BACKGROUND AND PURPOSE: Flow diverters are currently indicated for treatment of large and complex intracranial aneurysms. The purpose of this study was to determine whether the indications of flow diversion can be safely extended to unruptured, small, saccular aneurysms (<10 >mm) of the anterior circulation.

METHODS: Forty patients treated with the pipeline embolization device (PED) were matched in a 1:4 fashion with 160 patients treated with stent-assisted coiling based on patient age, sex, aneurysm location, and aneurysm size. Procedural complications, angiographic results, and clinical outcomes were analyzed and compared.

RESULTS: The rate of periprocedural complications was 5% in the PED …

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 …

Expression Of C-Fos In Hilar Mossy Cells Of The Dentate Gyrus In Vivo., Aine M Duffy, Michael J Schaner, Jeannie Chin, Helen E Scharfman

Department of Neuroscience Faculty Papers

Granule cells (GCs) of the dentate gyrus (DG) are considered to be quiescent--they rarely fire action potentials. In contrast, the other glutamatergic cell type in the DG, hilar mossy cells (MCs) often have a high level of spontaneous activity based on recordings in hippocampal slices. MCs project to GCs, so activity in MCs could play an important role in activating GCs. Therefore, we investigated whether MCs were active under basal conditions in vivo, using the immediate early gene c-fos as a tool. We hypothesized that MCs would exhibit c-fos expression even if rats were examined randomly, under normal housing conditions. …

Erps Reveal The Temporal Dynamics Of Auditory Word Recognition In Specific Language Impairment., Jeffrey G Malins, Amy S Desroches, Erin K Robertson, Randy Lynn Newman, Lisa M D Archibald, Marc F Joanisse

Brain and Mind Institute Researchers' Publications

We used event-related potentials (ERPs) to compare auditory word recognition in children with specific language impairment (SLI group; N=14) to a group of typically developing children (TD group; N=14). Subjects were presented with pictures of items and heard auditory words that either matched or mismatched the pictures. Mismatches overlapped expected words in word-onset (cohort mismatches; see: DOLL, hear: dog), rhyme (CONE -bone), or were unrelated (SHELL -mug). In match trials, the SLI group showed a different pattern of N100 responses to auditory stimuli compared to the TD group, indicative of early auditory processing differences in SLI. However, the phonological mapping …

Dynamic And Opposing Adjustment Of Movement Cancellation And Generation In An Oculomotor Countermanding Task., Brian D Corneil, Joshua C Cheng, Samanthi C Goonetilleke

Brain and Mind Institute Researchers' Publications

Adaptive adjustments of strategies help optimize behavior in a dynamic and uncertain world. Previous studies in the countermanding (or stop-signal) paradigm have detailed how reaction times (RTs) change with trial sequence, demonstrating adaptive control of movement generation. Comparatively little is known about the adaptive control of movement cancellation in the countermanding task, mainly because movement cancellation implies the absence of an outcome and estimates of movement cancellation require hundreds of trials. Here, we exploit a within-trial proxy of movement cancellation based on recordings of neck muscle activity while human subjects attempted to cancel large eye-head gaze shifts. On a subset …

Intracranial Injection Of Gammagard, A Human Ivig, Modulates The Inflammatory Response Of The Brain And Lowers AΒ In App/Ps1 Mice Along A Different Time Course Than Anti-AΒ Antibodies, Tiffany L. Sudduth, Abigail Greenstein, Donna M. Wilcock

Sanders-Brown Center on Aging Faculty Publications

Gammagard IVIg is a therapeutic approach to treat Alzheimer's disease currently in phase 3 clinical trials. Despite the reported efficacy of the approach the mechanism of action is poorly understood. We have previously shown that intracranial injection of anti-Aβ antibodies into the frontal cortex and hippocampus reveals important information regarding the time course of events once the agent is in the brain. In the current study we compared IVIg, mouse-pooled IgG, and the anti-Aβ antibody 6E10 injected intracranially into the frontal cortex and hippocampus of 7-month-old APP/PS1 mice. We established a time course of events ranging from 1 …

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 …

Prefrontal Neurons Of Opposite Spatial Preference Display Distinct Target Selection Dynamics., Therese Lennert, Julio C Martinez-Trujillo

Brain and Mind Institute Researchers' Publications

Neurons in the primate dorsolateral prefrontal cortex (dlPFC) of one hemisphere are selective for the location of attended targets in both visual hemifields. Whether dlPFC neurons with selectivity for opposite hemifields directly compete with each other for target selection or instead play distinct roles during the allocation of attention remains unclear. We explored this issue by recording neuronal responses in the right dlPFC of two macaques while they allocated attention to a target in one hemifield and ignored a distracter on the opposite side. Forty-nine percent of the recorded neurons were target location selective. Neurons selective for contralateral targets (58%) …

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

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. …

A Study Of Small Rnas From Cerebral Neocortex Of Pathology-Verified Alzheimer's Disease, Dementia With Lewy Bodies, Hippocampal Sclerosis, Frontotemporal Lobar Dementia, And Non-Demented Human Controls, Sébastien S. Hébert, Wang-Xia Wang, Qi Zhu, Peter T. Nelson

Sanders-Brown Center on Aging Faculty Publications

MicroRNAs (miRNAs) are small (20-22 nucleotides) regulatory non-coding RNAs that strongly influence gene expression. Most prior studies addressing the role of miRNAs in neurodegenerative diseases (NDs) have focused on individual diseases such as Alzheimer's disease (AD), making disease-to-disease comparisons impossible. Using RNA deep sequencing, we sought to analyze in detail the small RNAs (including miRNAs) in the temporal neocortex gray matter from non-demented controls (n = 2), AD (n = 5), dementia with Lewy bodies (n = 4), hippocampal sclerosis of aging (n = 4), and frontotemporal lobar dementia (FTLD) (n = 5) cases, together accounting for the most prevalent …

Properties Of Ribbon And Non-Ribbon Release From Rod Photoreceptors Revealed By Visualizing Individual Synaptic Vesicles., Minghui Chen, Matthew J. Van Hook, David Zenisek, Wallace B. Thoreson

Journal Articles: Pharmacology & Experimental Neuroscience

Vesicle release from rod photoreceptors is regulated by Ca(2+) entry through L-type channels located near synaptic ribbons. We characterized sites and kinetics of vesicle release in salamander rods by using total internal reflection fluorescence microscopy to visualize fusion of individual synaptic vesicles. A small number of vesicles were loaded by brief incubation with FM1-43 or a dextran-conjugated, pH-sensitive form of rhodamine, pHrodo. Labeled organelles matched the diffraction-limited size of fluorescent microspheres and disappeared rapidly during stimulation. Consistent with fusion, depolarization-evoked vesicle disappearance paralleled electrophysiological release kinetics and was blocked by inhibiting Ca(2+) influx. Rods maintained tonic release at resting membrane …

Acute Alcohol Consumption Impairs Controlled But Not Automatic Processes In A Psychophysical Pointing Paradigm., Kevin Johnston, Brian Timney, Melvyn A Goodale

Brain and Mind Institute Researchers' Publications

Numerous studies have investigated the effects of alcohol consumption on controlled and automatic cognitive processes. Such studies have shown that alcohol impairs performance on tasks requiring conscious, intentional control, while leaving automatic performance relatively intact. Here, we sought to extend these findings to aspects of visuomotor control by investigating the effects of alcohol in a visuomotor pointing paradigm that allowed us to separate the influence of controlled and automatic processes. Six male participants were assigned to an experimental "correction" condition in which they were instructed to point at a visual target as quickly and accurately as possible. On a small …

Mice With Deficient Bk Channel Function Show Impaired Prepulse Inhibition And Spatial Learning, But Normal Working And Spatial Reference Memory., Marei Typlt, Magdalena Mirkowski, Erin Azzopardi, Lukas Ruettiger, Peter Ruth, Susanne Schmid

Brain and Mind Institute Researchers' Publications

Genetic variations in the large-conductance, voltage- and calcium activated potassium channels (BK channels) have been recently implicated in mental retardation, autism and schizophrenia which all come along with severe cognitive impairments. In the present study we investigate the effects of functional BK channel deletion on cognition using a genetic mouse model with a knock-out of the gene for the pore forming α-subunit of the channel. We tested the F1 generation of a hybrid SV129/C57BL6 mouse line in which the slo1 gene was deleted in both parent strains. We first evaluated hearing and motor function to establish the suitability of this …