Brain activation during string playing

This chapter attempts to integrate data from both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to elucidate the activation of the cortical areas in musical performance for both execution and imagination of music during string playing. In both fMRI and EEG experiments, playing the music was compared with imagining the music. This allowed separation of the areas mainly involved in motor execution from those involved in imagining, planning, and working memory, thus differentiating musical from purely motor areas.

Stability analysis of a mono inverter dual sensorless motors system

When a single brush-less dc motor is fed by an inverter with a sensor-less algorithm embedded in the switching controller, the system exhibits a linear and stable output in terms of the speed and torque. However, with two motors modulated by the same inverter, the system is unstable and rendered useless for a steady application, unless provided with some resistive damping on the supply lines. The project discusses and analysis the stability of such a system through simulations and hardware demonstrations and also will discuss a method to derive the values of these damping.

Localization of DJ-1 mRNA in the mouse brain

DJ-1 is mutated in autosomal recessive, early onset Parkinson's disease but the exact localization of the DJ-1 gene product in the mammalian brain is largely unknown. We aimed to evaluate the DJ-1 mRNA expression pattern in the mouse brain. Serial coronal sections of brains of five male and five female adult mice were investigated by using in situ hybridization with a DJ-1 specific 35S-labeled oligonucleotide probe. Hybridized sections were analyzed after exposure to autoradiography films and after coating with a photographic emulsion. DJ-1 was heterogeneously expressed throughout the mouse central nervous system. A high expression of DJ-1 mRNA was detected in neuronal and non-neuronal populations of several structures of the motor system such as the substantia nigra, the red nucleus, the caudate putamen, the globus pallidus, and the deep nuclei of the cerebellum. Furthermore, DJ-1 mRNA was also highly expressed in non-motor structures including the hippocampus, the olfactory bulb, the reticular nucleus of the thalamus, and the piriform cortex. The high expression of DJ-1 mRNA in brain regions involved in motor control is compatible with the occurrence of parkinsonian symptoms after DJ-1 mutations. However, expression in other regions indicates that a dysfunction of DJ-1 may contribute to additional clinical features in patients with a DJ-1 mutation.

The lifestyle of our kids (LOOK) project: outline of methods

This methods paper outlines the overall design of a community-based multidisciplinary longitudinal study with the intent to stimulate interest and communication from scientists and practitioners studying the role of physical activity in preventive medicine. In adults, lack of regular exercise is a major risk factor in the development of chronic degenerative diseases and is a major contributor to obesity, and now we have evidence that many of our children are not sufficiently active to prevent early symptoms of chronic disease. The lifestyle of our kids (LOOK) study investigates how early physical activity contributes to health and development, utilizing a longitudinal design and a cohort of eight hundred and thirty 7-8-year-old (grade 2) school children followed to age 11-12 years (grade 6), their average family income being very close to that of Australia. We will test two hypotheses, that (a) the quantity and quality of physical activity undertaken by primary school children will influence their psychological and physical health and development; (b) compared with existing practices in primary schools, a physical education program administered by visiting specialists will enhance health and development, and lead to a more positive perception of physical activity. To test the first hypothesis we will monitor all children longitudinally over the 4 years. To test the second we will involve an intervention group of 430 children who receive two 50min physical education classes every week from visiting specialists and a control group of 400 who continue with their usual primary school physical education with their class-room teachers. At the end of grades 2, 4, and 6 we will measure several areas of health and development including blood risk factors for chronic disease, cardiovascular structure and function, physical fitness, psychological characteristics and perceptions of physical activity, bone structure and strength, motor control, body composition, nutritional intake, influence of teachers and family, and academic performance.

Sleepwalking, REM sleep behaviour disorder and overlap parasomnia in patients with Parkinson's disease

BACKGROUND/AIMS In a questionnaire survey, we identified 36 (9%) of 417 Parkinson's disease (PD) patients with sleepwalking (SW); 72% of them also had a history of REM sleep behaviour disorder (RBD). We aimed to assess the clinical and polysomnographic characteristics of SW in PD and to compare them to patients with PD with and without a history of RBD. METHODS We performed video-polysomnography and detailed clinical examination in 30 PD patients from the above-mentioned survey: 10 patients with a history of SW, 10 patients with a history of RBD, and 10 patients with no history of either SW or RBD. RESULTS PD patients with SW had higher depression, anxiety and Hoehn & Yahr scores and lower activities of daily living scores than patients without a history of RBD but did not differ from patients with RBD. Patients with SW and RBD also had more often dyskinesia and hallucinations. By polysomnography, RBD was observed in 8 patients with SW and in all patients with a history of RBD. A total of 5 patients without a history of either SW or RBD had REM sleep without atonia without behavioural peculiarities. CONCLUSION SW in PD is associated with depression, higher disease severity and functional disability. The simultaneous occurrence of SW and RBD (overlap parasomnia) in most patients suggests a common underlying disturbance of motor control during sleep in PD, with variable manifestations in different sleep stages.

On the interaction of attentional focus and gaze: The quiet eye inhibits focus-related performance decrements

To date, despite a large body of evidence in favor of the advantage of an effect-related focus of attention compared with a movement-related focus of attention in motor control and learning, the role of vision in this context remains unclear. Therefore, in a golf-putting study, the relation between attentional focus and gaze behavior (in particular, quiet eye, or QE) was investigated. First, the advantage of an effect-related focus, as well as of a long QE duration, could be replicated. Furthermore, in the online-demanding task of golf putting, high performance was associated with later QE offsets. Most decisively, an interaction between attentional focus and gaze behavior was revealed in such a way that the efficiency of the QE selectively manifested under movement-related focus instructions. As these findings suggest neither additive effects nor a causal chain, an alternative hypothesis is introduced explaining positive QE effects by the inhibition of not-to-be parameterized movement variants.

Effects of (un)predictable whole body vibrations on visual performance

Over recent years, it has repeatedly been shown that optimal gaze strategies enhance motor control (e.g., Foulsham, 2015). However, little is known, whether, vice versa, visual performance can be improved by optimized motor control. Consequently, in two studies, we investigated visual performance as a function of motor control strategies and task parameters, respectively. In Experiment 1, 72 participants were tested on visual acuity (Landolt) and contrast sensitivity (Grating), while standing in two different postures (upright vs. squat) on a ZEPTOR-platform that vibrated at four different frequencies (0, 4, 8, 12 Hz). After each test, perceived exertion (Borg) was assessed. Significant interactions were revealed for both tests, Landolt: F(3,213)=13.25, p<.01, ηp2=.16, Grating: F(3,213)=4.27, p<.01, ηp2=.06, elucidating a larger loss of acuity/contrast sensitivity with increasing frequencies for the upright compared with the squat posture. For perceived exertion, however, a diametrical interaction for frequency was found for acuity, F(3,213)=7.45, p<.01, ηp2=.09, and contrast sensitivity, F(3,213)=7.08, p < .01, ηp2=.09, substantiating that the impaired visual performance cannot be attributed to exertion. Consequently, the squat posture could permit better head and, hence, gaze stabilization. In Experiment 2, 64 participants performed the same tests while standing in a squat position on a ski-simulator, which vibrated with two different frequencies (2.4, 3.6 Hz) and amplitudes (50, 100 mm) in a predictable or unpredictable manner. Control strategies were identified by tracking segmental motion, which allows to derive damping characteristics. Considerable main effects were found for frequency, all F’s(1,52)>10.31, all p’s<.01, all ηp2’s>.16, as well as, in the acuity test, for predictability, F(1,52)=10.31, p<.01, ηp2=.17, and by tendency for amplitude, F(1,52)=3.53, p=.06, ηp2=.06. A significant correlation between the damping amplitude in the knee joint and the performance drop in visual acuity, r=-.97, p<.001, again points towards the importance of motor control strategies to maintain optimal visual performance.

Mechanical actuator for biomimetic propulsion and the effect of the caudal fin elasticity on the swimming performance

This paper presents a mechanical actuator for the biomimetic propulsion of swimming devices and the experimental study of the effect of the caudal fin elasticity on the overall performance. The design of the proposed drive allows the DC motor to operate at constant speed, so all the power of the motor is spent only for the motion of the caudal fin. A prototype of the actuator, in which the caudal fin serves as a driving element, is manufactured and tested in both laboratory and natural conditions. The swimming speed, the thrust efficiency and the maneuverability are evaluated for caudal fins with different stiffness. The caudal fin whose rigidity varies relative to both vertical and horizontal cross-section, exhibits the best performance. The achieved results also confirm that the proposed actuator could be of great interest to applications in the field of underwater operation, ocean investigation and environmental protection.

Dysfunctional profile for patients in physical neurorehabilitation of upper limb

This paper proposes a first approach to Objective Motor Assessment (OMA) methodology. Also, it introduces the Dysfunctional profile (DP) concept. DP consists of a data matrix characterizing the Upper Limb (UL) physical alterations of a patient with Acquired Brain Injury (ABI) during the rehabilitation process. This research is based on the comparison methology of UL movement between subjects with ABI and healthy subjects as part of OMA. The purpose of this comparison is to classify subjects according to their motor control and subsequently issue a functional assessment of the movement. For this purpose Artificial Neural Networks (ANN) have been used to classify patients. Different network structures are tested. The obtained classification accuracy was 95.65%. This result allows the use of ANNs as a viable option for dysfunctional assessment. This work can be considered a pilot study for further research to corroborate these results.

Targeted deletion of the mouse POU domain gene Brn-3a causes selective loss of neurons in the brainstem and trigeminal ganglion, uncoordinated limb movement, and impaired suckling.

The Brn-3 subfamily of POU domain genes are expressed in sensory neurons and in select brainstem nuclei. Earlier work has shown that targeted deletion of the Brn-3b and Brn-3c genes produce, respectively, defects in the retina and in the inner ear. We show herein that targeted deletion of the Brn-3a gene results in defective suckling and in uncoordinated limb and trunk movements, leading to early postnatal death. Brn-3a (-/-) mice show a loss of neurons in the trigeminal ganglia, the medial habenula, the red nucleus, and the caudal region of the inferior olivary nucleus but not in the retina and dorsal root ganglia. In the trigeminal and dorsal root ganglia, but not in the retina, there is a marked decrease in the frequency of neurons expressing Brn-3b and Brn-3c, suggesting that Brn-3a positively regulates Brn-3b and Brn-3c expression in somatosensory neurons. Thus, Brn-3a exerts its major developmental effects in somatosensory neurons and in brainstem nuclei involved in motor control. The pheno-types of Brn-3a, Brn-3b, and Brn-3c mutant mice indicate that individual Brn-3 genes have evolved to control development in the auditory, visual, or somatosensory systems and that despite differences between these systems in transduction mechanisms, sensory organ structures, and central information processing, there may be fundamental homologies in the genetic regulatory events that control their development.

Feedback circuitry within a song-learning pathway.

The song system of birds consists of several neural pathways. One of these, the anterior forebrain pathway, is necessary for the acquisition but not for the production of learned song in zebra finches. It has been shown that the anterior forebrain pathway sequentially connects the following nuclei: the high vocal center, area X of lobus parolfactorius, the medial portion of the dorsolateral thalamic nucleus, the lateral magnocellular nucleus of anterior neostriatum (IMAN), and the robust nucleus of the archistriatum (RA). We now show in zebra finches (Taeniopygia guttata) that IMAN cells that project to RA also project to area X, forming a feedback loop within the anterior forebrain pathway. The axonal endings of the IMAN projection into area X form cohesive and distinct domains. Small injections of tracer in subregions of area X backfill a spatially restricted subset of cells in IMAN, that, in turn, send projections to RA that are arranged in horizontal layers, which may correspond to the functional representation of vocal tract muscles demonstrated by others. We infer from our data that there is a myotopic representation throughout the anterior forebrain pathway. In addition, we suggest that the parcellation of area X into smaller domains by the projection from IMAN highlights a functional architecture within X, which might correspond to units of motor control, to the representation of acoustic features of song, or both.

Proactive and reactive inhibition during overt and covert actions. An electrical neuroimaging study.

Response inhibition is the ability to suppress inadequate but automatically activated, prepotent or ongoing response tendencies. In the framework of motor inhibition, two distinct operating strategies have been described: “proactive” and “reactive” control modes. In the proactive modality, inhibition is recruited in advance by predictive signals, and actively maintained before its enactment. Conversely, in the reactive control mode, inhibition is phasically enacted after the detection of the inhibitory signal. To date, ample evidence points to a core cerebral network for reactive inhibition comprising the right inferior frontal gyrus (rIFG), the presupplementary motor area (pre-SMA) and the basal ganglia (BG). Moreover, fMRI studies showed that cerebral activations during proactive and reactive inhibition largely overlap. These findings suggest that at least part of the neural network for reactive inhibition is recruited in advance, priming cortical regions in preparation for the upcoming inhibition. So far, proactive and reactive inhibitory mechanisms have been investigated during tasks in which the requested response to be stopped or withheld was an “overt” action execution (AE) (i.e., a movement effectively performed). Nevertheless, inhibitory mechanisms are also relevant for motor control during “covert actions” (i.e., potential motor acts not overtly performed), such as motor imagery (MI). MI is the conscious, voluntary mental rehearsal of action representations without any overt movement. Previous studies revealed a substantial overlap of activated motor-related brain networks in premotor, parietal and subcortical regions during overtly executed and imagined movements. Notwithstanding this evidence for a shared set of cerebral regions involved in encoding actions, whether or not those actions are effectively executed, the neural bases of motor inhibition during MI, preventing covert action from being overtly performed, in spite of the activation of the motor system, remain to be fully clarified. Taking into account this background, we performed a high density EEG study evaluating cerebral mechanisms and their related sources elicited during two types of cued Go/NoGo task, requiring the execution or withholding of an overt (Go) or a covert (MI) action, respectively. The EEG analyses were performed in two steps, with different aims: 1) Analysis of the “response phase” of the cued overt and covert Go/NoGo tasks, for the evaluation of reactive inhibitory control of overt and covert actions. 2) Analysis of the “preparatory phase” of the cued overt and covert Go/NoGo EEG datasets, focusing on cerebral activities time-locked to the preparatory signals, for the evaluation of proactive inhibitory mechanisms and their related neural sources. For these purposes, a spatiotemporal analysis of the scalp electric fields was applied on the EEG data recorded during the overt and covert Go/NoGo tasks. The spatiotemporal approach provide an objective definition of time windows for source analysis, relying on the statistical proof that the electric fields are different and thus generated by different neural sources. The analysis of the “response phase” revealed that key nodes of the inhibitory circuit, underpinning inhibition of the overt movement during the NoGo response, were also activated during the MI enactment. In both cases, inhibition relied on the activation of pre-SMA and rIFG, but with different temporal patterns of activation in accord with the intended “covert” or “overt” modality of motor performance. During the NoGo condition, the pre-SMA and rIFG were sequentially activated, pointing to an early decisional role of pre-SMA and to a later role of rIFG in the enactment of inhibitory control of the overt action. Conversely, a concomitant activation of pre-SMA and rIFG emerged during the imagined motor response. This latter finding suggested that an inhibitory mechanism (likely underpinned by the rIFG), could be prewired into a prepared “covert modality” of motor response, as an intrinsic component of the MI enactment. This mechanism would allow the rehearsal of the imagined motor representations, without any overt movement. The analyses of the “preparatory phase”, confirmed in both overt and covert Go/NoGo tasks the priming of cerebral regions pertaining to putative inhibitory network, reactively triggered in the following response phase. Nonetheless, differences in the preparatory strategies between the two tasks emerged, depending on the intended “overt” or “covert” modality of the possible incoming motor response. During the preparation of the overt Go/NoGo task, the cue primed the possible overt response programs in motor and premotor cortex. At the same time, through preactivation of a pre-SMA-related decisional mechanism, it triggered a parallel preparation for the successful response selection and/or inhibition during the subsequent response phase. Conversely, the preparatory strategy for the covert Go/NoGo task was centred on the goal-oriented priming of an inhibitory mechanism related to the rIFG that, being tuned to the instructed covert modality of the motor performance and instantiated during the subsequent MI enactment, allowed the imagined response to remain a potential motor act. Taken together, the results of the present study demonstrate a substantial overlap of cerebral networks activated during proactive recruitment and subsequent reactive enactment of motor inhibition in both overt and covert actions. At the same time, our data show that preparatory cues predisposed ab initio a different organization of the cerebral areas (in particular of the pre-SMA and rIFG) involved with sensorimotor transformations and motor inhibitory control for executed and imagined actions. During the preparatory phases of our cued overt and covert Go/NoGo tasks, the different adopted strategies were tuned to the “how” of the motor performance, reflecting the intended overt and covert modality of the possible incoming action.

Kernicterus e icterícia neonatal : revisão teórica a propósito de um caso clínico

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

Experimental muscle pain changes feedforward postural responses of the trunk muscles

Many studies have identified changes in trunk muscle recruitment in clinical low back pain (LBP). However, due to the heterogeneity of the LBP population these changes have been variable and it has been impossible to identify a cause-effect relationship. Several studies have identified a consistent change in the feed-forward postural response of transversus abdominis (TrA), the deepest abdominal muscle, in association with arm movements in chronic LBP. This study aimed to determine whether the feedforward recruitment of the trunk muscles in a postural task could be altered by acute experimentally induced LBP. Electromyographic (EMG) recordings of the abdominal and paraspinal muscles were made during arm movements in a control trial, following the injection of isotonic (non-painful) and hypertonic (painful) saline into the longissimus muscle at L4, and during a 1-h follow-up. Movements included rapid arm flexion in response to a light and repetitive arm flexion-extension. Temporal and spatial EMG parameters were measured. The onset and amplitude of EMG of most muscles was changed in a variable manner during the period of experimentally induced pain. However, across movement trials and subjects the activation of TrA was consistently reduced in amplitude or delayed. Analyses in the time and frequency domain were used to confirm these findings. The results suggest that acute experimentally induced pain may affect feedforward postural activity of the trunk muscles. Although the response was variable, pain produced differential changes in the motor control of the trunk muscles, with consistent impairment of TrA activity.