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Sample records for cat motor cortex

  1. Linear summation of cat motor cortex outputs.

    PubMed

    Ethier, Christian; Brizzi, Laurent; Darling, Warren G; Capaday, Charles

    2006-05-17

    Recruitment of movement-related muscle synergies involves the functional linking of motor cortical points. We asked how the outputs of two simultaneously stimulated motor cortical points would interact. To this end, experiments were done in ketamine-anesthetized cats. When prolonged (e.g., 500 ms) trains of intracortical microstimulation were applied in the primary motor cortex, stimulus currents as low as 10-20 microA evoked coordinated movements of the contralateral forelimb. Paw kinematics in three dimensions and the electromyographic (EMG) activity of eight muscles were simultaneously recorded. We show that the EMG outputs of two cortical points simultaneously stimulated are additive. The movements were represented as displacement vectors pointing from initial to final paw position. The displacement vectors resulting from simultaneous stimulation of two cortical points pointed in nearly the same direction as the algebraic resultant vector. Linear summation of outputs was also found when inhibition at one of the cortical points was reduced by GABAA receptor antagonists. A simple principle emerges from these results. Notwithstanding the underlying complex neuronal circuitry, motor cortex outputs combine nearly linearly in terms of movement direction and muscle activation patterns. Importantly, simultaneous activation does not change the nature of the output at each point. An additional implication is that not all possible movements need be explicitly represented in the motor cortex; a large number of different movements may be synthesized from a smaller repertoire.

  2. Accurate stepping on a narrow path: mechanics, EMG, and motor cortex activity in the cat

    PubMed Central

    Farrell, Brad J.; Bulgakova, Margarita A.; Sirota, Mikhail G.; Prilutsky, Boris I.

    2015-01-01

    How do cats manage to walk so graciously on top of narrow fences or windowsills high above the ground while apparently exerting little effort? In this study we investigated cat full-body mechanics and the activity of limb muscles and motor cortex during walking along a narrow 5-cm path on the ground. We tested the hypotheses that during narrow walking 1) lateral stability would be lower because of the decreased base-of-support area and 2) the motor cortex activity would increase stride-related modulation because of imposed demands on lateral stability and paw placement accuracy. We measured medio-lateral and rostro-caudal dynamic stability derived from the extrapolated center of mass position with respect to the boundaries of the support area. We found that cats were statically stable in the frontal plane during both unconstrained and narrow-path walking. During narrow-path walking, cats walked slightly slower with more adducted limbs, produced smaller lateral forces by hindlimbs, and had elevated muscle activities. Of 174 neurons recorded in cortical layer V, 87% of forelimb-related neurons (from 114) and 90% of hindlimb-related neurons (from 60) had activities during narrow-path walking distinct from unconstrained walking: more often they had a higher mean discharge rate, lower depth of stride-related modulation, and/or longer period of activation during the stride. These activity changes appeared to contribute to control of accurate paw placement in the medio-lateral direction, the width of the stride, rather than to lateral stability control, as the stability demands on narrow-path and unconstrained walking were similar. PMID:26354314

  3. Effects of stimulation parameters and electrode location on thresholds for epidural stimulation of cat motor cortex

    NASA Astrophysics Data System (ADS)

    Wongsarnpigoon, Amorn; Grill, Warren M.

    2011-12-01

    Epidural electrical stimulation (ECS) of the motor cortex is a developing therapy for neurological disorders. Both placement and programming of ECS systems may affect the therapeutic outcome, but the treatment parameters that will maximize therapeutic outcomes and minimize side effects are not known. We delivered ECS to the motor cortex of anesthetized cats and investigated the effects of electrode placement and stimulation parameters on thresholds for evoking motor responses in the contralateral forelimb. Thresholds were inversely related to stimulation frequency and the number of pulses per stimulus train. Thresholds were lower over the forelimb representation in motor cortex (primary site) than surrounding sites (secondary sites), and thresholds at sites <4 mm away from the primary site were significantly lower than at sites >4 mm away. Electrode location and montage influenced the effects of polarity on thresholds: monopolar anodic and cathodic thresholds were not significantly different over the primary site, cathodic thresholds were significantly lower than anodic thresholds over secondary sites and bipolar thresholds were significantly lower with the anode over the primary site than with the cathode over the primary site. A majority of bipolar thresholds were either between or equal to the respective monopolar thresholds, but several bipolar thresholds were greater than or less than the monopolar thresholds of both the anode and cathode. During bipolar stimulation, thresholds were influenced by both electric field superposition and indirect, synaptically mediated interactions. These results demonstrate the influence of stimulation parameters and electrode location during cortical stimulation, and these effects should be considered during the programming of systems for therapeutic cortical stimulation.

  4. A regularized point process generalized linear model for assessing the functional connectivity in the cat motor cortex.

    PubMed

    Chen, Zhe; Putrino, David F; Ba, Demba E; Ghosh, Soumya; Barbieri, Riccardo; Brown, Emery N

    2009-01-01

    Identification of multiple simultaneously recorded neural spike train recordings is an important task in understanding neuronal dependency, functional connectivity, and temporal causality in neural systems. An assessment of the functional connectivity in a group of ensemble cells was performed using a regularized point process generalized linear model (GLM) that incorporates temporal smoothness or contiguity of the solution. An efficient convex optimization algorithm was then developed for the regularized solution. The point process model was applied to an ensemble of neurons recorded from the cat motor cortex during a skilled reaching task. The implications of this analysis to the coding of skilled movement in primary motor cortex is discussed.

  5. [Prolonged homosynaptic depression of the impulse reactions of the motor cortex neurons in the cat].

    PubMed

    Sil'kis, I G; Rapoport, S Sh; Veber, N V; Gushchin, A M

    1993-01-01

    It is shown that in the motor and the visual cortices of the cat the homosynaptic long-term posttetanic depression (LTD) of monosynaptic impulse responses of the cortical neurons may be induced in the tetanized input. Homosynaptic LTD appears as a decrease of the probability of the monosynaptic discharges or an increase in the latency of the monosynaptic responses. The cortical homosynaptic depression possesses the same properties as the hippocampal LTD, namely, the longevity, input specificity, cooperativity, and associativity. The possible mechanisms of the homosynaptic LTD induction are discussed. The effect may be determined, on the one hand, as Ca-dependent phenomenon, and on the other hand, as the LTP of monosynaptic reactions of the input inhibitory interneurons. It is supposed that the homosynaptic LTD of the impulse reactions of the cortical neurons may be one of the basic mechanisms in certain learning tasks, such as habituation or extinction.

  6. Patterns of spatio-temporal correlations in the neural activity of the cat motor cortex during trained forelimb movements.

    PubMed

    Ghosh, Soumya; Putrino, David; Burro, Bianca; Ring, Alexander

    2009-06-01

    In order to study how neurons in the primary motor cortex (MI) are dynamically linked together during skilled movement, we recorded simultaneously from many cortical neurons in cats trained to perform a reaching and retrieval task using their forelimbs. Analysis of task-related spike activity in the MI of the hemisphere contralateral to the reaching forelimb (in identified forelimb or hindlimb representations) recorded through chronically implanted microwires, was followed by pairwise evaluation of temporally correlated activity in these neurons during task performance using shuffle corrected cross-correlograms. Over many months of recording, a variety of task-related modulations of neural activities were observed in individual efferent zones. Positively correlated activity (mainly narrow peaks at zero or short latencies) was seen during task performance frequently between neurons recorded within the forelimb representation of MI, rarely within the hindlimb area of MI, and never between forelimb and hindlimb areas. Correlated activity was frequently observed between neurons with different patterns of task-related activity or preferential activity during different task elements (reaching, feeding, etc.), and located in efferent zones with dissimilar representation as defined by intracortical microstimulation. The observed synchronization of action potentials among selected but functionally varied groups of MI neurons possibly reflects dynamic recruitment of network connections between efferent zones during skilled movement.

  7. Central regulation of motor cortex neuronal responses to forelimb nerve inputs during precision walking in the cat

    PubMed Central

    Marple-Horvat, D E; Armstrong, D M

    1999-01-01

    The responses of neurones in forelimb motor cortex to impulse volleys evoked by single pulse electrical stimulation (at 1.5 or 2 times the threshold for most excitable nerve fibres) of the superficial radial (SR) and ulnar (UL) nerves of the contralateral forelimb were studied in awake cats both resting quietly and walking on a horizontal ladder. Nerve volley amplitude was monitored by recording the compound action potential elicited by the stimulus. In the resting animal 34/82 (41 %) cells yielded statistically significant responses to SR stimulation, and 20/72 (28 %) responded to UL stimulation. Some responses were confined to or began with an increase in firing probability (‘excitatory’ responses) and others with a decrease in firing (‘inhibitory’ responses), typically including a brief interruption of the spike train (zero rate). Cells responding to both nerves usually yielded responses similar in type. Most (78 %) response onset latencies were less than 30 ms. Responses involved the addition or subtraction of from 3.4 to 0.1 impulses stimulus−1 (most < 1 impulse stimulus−1). The distribution of response sizes was continuous down to the smallest values, i.e. there was no ‘gap’ which would represent a clear separation into ‘responsive’ and ‘unresponsive’ categories. Responses were commonest in the lateral part of the pericruciate cortex, and commoner among pyramidal tract neurones (PTNs) than non-PTNs. During ladder walking most cells generated a rhythmic step-related discharge; in assessing the size of responses to nerve stimulation (20 studied, from 13 cells) this activity was first subtracted. Response onset latencies (90 % < 30 ms) and durations showed little or no change. Although most cells were overall more active than during rest both ‘excitatory’ and ‘inhibitory’ responses in both PTNs and non-PTNs were often markedly reduced in large parts of the step cycle; over some (usually brief) parts responses approached or

  8. Role of sensory-motor cortex activity in postnatal development of corticospinal axon terminals in the cat.

    PubMed

    Friel, Kathleen M; Martin, John H

    2005-04-25

    The initial pattern of corticospinal (CS) terminations, as axons grow into the spinal gray matter, bears little resemblance to the pattern later in development and in maturity. This is because of extensive axon pruning and local axon terminal growth during early postnatal development. Pruning is driven by activity-dependent competition between the CS systems on each side during postnatal weeks (PW) 3-7. It is not known whether CS axon terminal growth and final topography are activity dependent. We examined the activity dependence of CS axon terminal growth and topography at different postnatal times. We inactivated sensory-motor cortex by infusion of the gamma-aminobutyric acid type A (GABA(A)) agonist muscimol and traced CS axons from the inactivated side. Inactivation between PW5 and PW7 produced permanent changes in projection topography, reduced local axon branching, and prevented development of dense clusters of presynaptic sites, which are normally characteristic of CS terminals. Inactivation at younger (PW3-5) and older (PW8-12) ages did not affect projection topography but impeded development of local axon branching and presynaptic site clusters. These effects were not due to increased cortical cell death during inactivation. Neural activity plays an important role in determining the morphology of CS terminals during the entire period of development, but, for the projection topography, the role of activity is exercised during a very brief period. This points to a complex, and possibly independent, regulation of termination topography and terminal morphology. Surprisingly, when a CS neuron's activity is blocked during early development, it does not recover lost connections later in development once activity resumes.

  9. Changes in the activity of units of the cat motor cortex with rapid conditioning and extinction of a compound eye blink movement.

    PubMed

    Aou, S; Woody, C D; Birt, D

    1992-02-01

    Patterns of spike activity were measured in the pericruciate cortex of conscious cats before and after development of a Pavlovian conditioned eye blink response. Unit activity was tested with presentations of a click conditioned stimulus (CS) and a hiss discriminative stimulus (DS) of similar intensity to the click. Unit discharge in response to the CS increased after conditioning, but not after backward conditioning when conditioned reflexes (CRs) were not performed. Rates of spontaneous, baseline discharge were not increased after conditioning with respect to rates of discharge measured in the naive state. It appeared that an increase in the ratio of CS-elicited discharge to background activity, together with an increase in the number of units responding to the CS after conditioning, supported discrimination of the CS from the DS and performance of the conditioned blink response. This is the first detailed characterization of patterns of a rapidly conditioned Pavlovian response. Activation of units by the CS preceded the onset of the CR, supporting the hypothesis that the activity played a role in initiating the conditioned eye blink movement. Extinction with retention of performance of the CR was associated with perseverance of the increased unit discharge in response to the CS. Extinction with substantially reduced performance of the CR was associated with diminution of the unit response to the CS below levels found with conditioning. Averages of patterns of spike activity elicited by the CS after conditioning showed components of discharge with onsets of 8-40 msec (alpha 1), 40-72 msec (alpha 2), 72-112 msec (beta), and greater than 112 msec (gamma), corresponding to each of four separate excitatory EMG components of the compound blink CR. Each component increased in magnitude after conditioning, relative to levels found in the naive state. The finding that long- as well as short-latency components of unit activation increased after conditioning supported the

  10. Dissociating motor cortex from the motor

    PubMed Central

    Schieber, Marc H

    2011-01-01

    Abstract During closed-loop control of a brain–computer interface, neurons in the primary motor cortex can be intensely active even though the subject may be making no detectable movement or muscle contraction. How can neural activity in the primary motor cortex become dissociated from the movements and muscles of the native limb that it normally controls? Here we examine circumstances in which motor cortex activity is known to dissociate from movement – including mental imagery, visuo-motor dissociation and instructed delay. Many such motor cortex neurons may be related to muscle activity only indirectly. Furthermore, the integration of thousands of synaptic inputs by individual α-motoneurons means that under certain circumstances even cortico-motoneuronal cells, which make monosynaptic connections to α-motoneurons, can become dissociated from muscle activity. The natural ability of motor cortex neurons under voluntarily control to become dissociated from bodily movement may underlie the utility of this cortical area for controlling brain–computer interfaces. PMID:22005673

  11. Learning in the Rodent Motor Cortex.

    PubMed

    Peters, Andrew J; Liu, Haixin; Komiyama, Takaki

    2017-03-31

    The motor cortex is far from a stable conduit for motor commands and instead undergoes significant changes during learning. An understanding of motor cortex plasticity has been advanced greatly using rodents as experimental animals. Two major focuses of this research have been on the connectivity and activity of the motor cortex. The motor cortex exhibits structural changes in response to learning, and substantial evidence has implicated the local formation and maintenance of new synapses as crucial substrates of motor learning. This synaptic reorganization translates into changes in spiking activity, which appear to result in a modification and refinement of the relationship between motor cortical activity and movement. This review presents the progress that has been made using rodents to establish the motor cortex as an adaptive structure that supports motor learning. Expected final online publication date for the Annual Review of Neuroscience Volume 40 is July 8, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  12. Motor cortex layer 4: less is more

    PubMed Central

    Barbas, Helen; García-Cabezas, Miguel Á.

    2015-01-01

    The stratified motor cortex is variously thought to either lack or contain layer 4. Yamawaki et al. described a functional layer 4 in mouse motor cortex with properties and connections similar to layer 4 in sensory areas. Their results bolster a theoretical framework suggesting all primary cortical areas are equivalent. PMID:25868984

  13. A functional microcircuit for cat visual cortex.

    PubMed Central

    Douglas, R J; Martin, K A

    1991-01-01

    1. We have studied in vivo the intracellular responses of neurones in cat visual cortex to electrical pulse stimulation of the cortical afferents and have developed a microcircuit that simulates much of the experimental data. 2. Inhibition and excitation are not separable events, because individual neurones are embedded in microcircuits that contribute strong population effects. Synchronous electrical activation of the cortex inevitably set in motion a sequence of excitation and inhibition in every neurone we recorded. The temporal form of this response depends on the cortical layer in which the neurone is located. Superficial layer (layers 2+3) pyramidal neurones show a more marked polysynaptic excitatory phase than the pyramids of the deep layers (layers 5+6). 3. Excitatory effects on pyramidal neurones, particularly the superficial layer pyramids, are in general not due to monosynaptic input from thalamus, but polysynaptic input from cortical pyramids. Since the thalamic input is transient it does not provide the major, sustained excitation arriving at any cortical neurone. Instead the intracortical excitatory connections provide the major component of the excitation. 4. The polysynaptic excitatory response would be sustained well after the stimulus, were it not for the suppressive effect of intracortical inhibition induced by the pulse stimulation. 5. Intracellular recording combined with ionophoresis of gamma-aminobutyric acid (GABA) agonists and antagonists showed that intracortical inhibition is mediated by GABAA and GABAB receptors. The GABAA component occurs in the early phase of the impulse response. It is reflected in the strong hyperpolarization that follows the excitatory response and lasts about 50 ms. The GABAB component occurs in the late phase of the response, and is reflected in a sustained hyperpolarization that lasts some 200-300 ms. Both components are seen in all cortical pyramidal neurones. However, the GABAA component appears more powerful

  14. An immunocytochemical mapping of somatostatin in the cat auditory cortex.

    PubMed

    Martín, F; Coveñas, R; Narváez, J A; Tramu, G

    2003-10-01

    Using an indirect immunoperoxidase technique, the localization of somatostatin-28 (1-12)-like immunoreactive fibers and cell bodies in the auditory cortex of the cat (anterior, primary, secondary, temporal, ventral, ventroposterior, posterior and dorsoposterior auditory fields) was studied. In general, the distribution of SOM-ir structures is widespread in the auditory cortex of the feline. A high density of immunoreactive fibers as well as a low density of cell bodies containing somatostatin were observed in all the layers of the eight above-mentioned auditory fields. These data indicate that somatostatin-28 (1-12) could act as a neurotransmitter and/or a neuromodulator in the auditory cortex of the cat. The origin of the SOM-ir fibers in the auditory cortex of the cat, as well as the issue of whether the cell bodies containing somatostatin-28 (1-12) are local or projecting neurons is discussed.

  15. Motor cortex inhibition induced by acoustic stimulation.

    PubMed

    Kühn, Andrea A; Sharott, Andrew; Trottenberg, Thomas; Kupsch, Andreas; Brown, Peter

    2004-09-01

    The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following acoustic stimulation occurs at the level of the motor cortex through reticulo-cortical projections or subcortically, perhaps through reticulo-spinal projections. We compared the influence of acoustic stimulation on motor effects elicited by TMS over motor cortical areas to those evoked with subcortical electrical stimulation (SES) through depth electrodes in five patients treated with deep brain stimulation for Parkinson's disease. SES bypasses the motor cortex, demonstrating any interaction with acoustic stimuli at the subcortical level. EMG was recorded from the contralateral biceps brachii muscle. Acoustic stimulation was delivered binaurally through headphones and used as a conditioning stimulus at an interstimulus interval of 50 ms. When TMS was used as the test stimulus, the area and amplitude of the conditioned motor response was significantly inhibited (area: 57.5+/-12.9%, amplitude: 47.9+/-7.4%, as percentage of unconditioned response) whereas facilitation occurred with SES (area: 110.1+/-4.3%, amplitude: 116.9+/-6.9%). We conclude that a startle-evoked activation of reticulo-cortical projections transiently inhibits the motor cortex.

  16. Motor Cortex Reorganization across the Lifespan

    ERIC Educational Resources Information Center

    Plowman, Emily K.; Kleim, Jeffrey A.

    2010-01-01

    The brain is a highly dynamic structure with the capacity for profound structural and functional change. Such neural plasticity has been well characterized within motor cortex and is believed to represent one of the neural mechanisms for acquiring and modifying motor behaviors. A number of behavioral and neural signals have been identified that…

  17. Vibrissa motor cortex activity suppresses contralateral whisking behavior.

    PubMed

    Ebbesen, Christian Laut; Doron, Guy; Lenschow, Constanze; Brecht, Michael

    2017-01-01

    Anatomical, stimulation and lesion data implicate vibrissa motor cortex in whisker motor control. Work on motor cortex has focused on movement generation, but correlations between vibrissa motor cortex activity and whisking are weak. The exact role of vibrissa motor cortex remains unknown. We recorded vibrissa motor cortex neurons during various forms of vibrissal touch, which were invariably associated with whisker protraction and movement. Free whisking, object palpation and social touch all resulted in decreased cortical activity. To understand this activity decrease, we performed juxtacellular recordings, nanostimulation and in vivo whole-cell recordings. Social touch resulted in decreased spiking activity, decreased cell excitability and membrane hyperpolarization. Activation of vibrissa motor cortex by intracortical microstimulation elicited whisker retraction, as if to abort vibrissal touch. Various vibrissa motor cortex inactivation protocols resulted in contralateral protraction and increased whisker movements. These data collectively point to movement suppression as a prime function of vibrissa motor cortex activity.

  18. Pinwheel-dipole configuration in cat early visual cortex.

    PubMed

    Ribot, Jérôme; Romagnoni, Alberto; Milleret, Chantal; Bennequin, Daniel; Touboul, Jonathan

    2016-03-01

    In the early visual cortex, information is processed within functional maps whose layouts are thought to underlie visual perception. However, the precise organization of these functional maps as well as their interrelationships remain unsettled. Here, we show that spatial frequency representation in cat early visual cortex exhibits singularities around which the map organizes like an electric dipole potential. These singularities are precisely co-located with singularities of the orientation map: the pinwheel centers. To show this, we used high resolution intrinsic optical imaging in cat areas 17 and 18. First, we show that a majority of pinwheel centers exhibit in their neighborhood both semi-global maximum and minimum in the spatial frequency map (i.e. extreme values of the spatial frequency in a hypercolumn). This contradicts pioneering studies suggesting that pinwheel centers are placed at the locus of a single spatial frequency extremum. Based on an analogy with electromagnetism, we proposed a mathematical model for a dipolar structure, accurately fitting optical imaging data. We conclude that a majority of orientation pinwheel centers form spatial frequency dipoles in cat early visual cortex. Given the functional specificities of neurons at singularities in the visual cortex, it is argued that the dipolar organization of spatial frequency around pinwheel centers could be fundamental for visual processing.

  19. Does intrinsic motivation enhance motor cortex excitability?

    PubMed

    Radel, Rémi; Pjevac, Dusan; Davranche, Karen; d'Arripe-Longueville, Fabienne; Colson, Serge S; Lapole, Thomas; Gruet, Mathieu

    2016-11-01

    Intrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single-pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor-evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM-related stimuli did not lead to a greater corticospinal excitability than EM-related stimuli or than stimuli with no motivational valence (ps > .20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research.

  20. Network and external perturbation induce burst synchronisation in cat cerebral cortex

    NASA Astrophysics Data System (ADS)

    Lameu, Ewandson L.; Borges, Fernando S.; Borges, Rafael R.; Batista, Antonio M.; Baptista, Murilo S.; Viana, Ricardo L.

    2016-05-01

    The brain of mammals are divided into different cortical areas that are anatomically connected forming larger networks which perform cognitive tasks. The cat cerebral cortex is composed of 65 areas organised into the visual, auditory, somatosensory-motor and frontolimbic cognitive regions. We have built a network of networks, in which networks are connected among themselves according to the connections observed in the cat cortical areas aiming to study how inputs drive the synchronous behaviour in this cat brain-like network. We show that without external perturbations it is possible to observe high level of bursting synchronisation between neurons within almost all areas, except for the auditory area. Bursting synchronisation appears between neurons in the auditory region when an external perturbation is applied in another cognitive area. This is a clear evidence that burst synchronisation and collective behaviour in the brain might be a process mediated by other brain areas under stimulation.

  1. The auditory representation of speech sounds in human motor cortex.

    PubMed

    Cheung, Connie; Hamiton, Liberty S; Johnson, Keith; Chang, Edward F

    2016-03-04

    In humans, listening to speech evokes neural responses in the motor cortex. This has been controversially interpreted as evidence that speech sounds are processed as articulatory gestures. However, it is unclear what information is actually encoded by such neural activity. We used high-density direct human cortical recordings while participants spoke and listened to speech sounds. Motor cortex neural patterns during listening were substantially different than during articulation of the same sounds. During listening, we observed neural activity in the superior and inferior regions of ventral motor cortex. During speaking, responses were distributed throughout somatotopic representations of speech articulators in motor cortex. The structure of responses in motor cortex during listening was organized along acoustic features similar to auditory cortex, rather than along articulatory features as during speaking. Motor cortex does not contain articulatory representations of perceived actions in speech, but rather, represents auditory vocal information.

  2. Interhemispheric Synchronization of Oscillatory Neuronal Responses in Cat Visual Cortex

    NASA Astrophysics Data System (ADS)

    Engel, Andreas K.; Konig, Peter; Kreiter, Andreas K.; Singer, Wolf

    1991-05-01

    Neurons in area 17 of cat visual cortex display oscillatory responses that can synchronize across spatially separate columns in a stimulus-specific way. Response synchronization has now been shown to occur also between neurons in area 17 of the right and left cerebral hemispheres. This synchronization was abolished by section of the corpus callosum. Thus, the response synchronization is mediated by corticocortical connections. These data are compatible with the hypothesis that temporal synchrony of neuronal discharges serves to bind features within and between the visual hemifields.

  3. Forelimb training drives transient map reorganization in ipsilateral motor cortex.

    PubMed

    Pruitt, David T; Schmid, Ariel N; Danaphongse, Tanya T; Flanagan, Kate E; Morrison, Robert A; Kilgard, Michael P; Rennaker, Robert L; Hays, Seth A

    2016-10-15

    Skilled motor training results in reorganization of contralateral motor cortex movement representations. The ipsilateral motor cortex is believed to play a role in skilled motor control, but little is known about how training influences reorganization of ipsilateral motor representations of the trained limb. To determine whether training results in reorganization of ipsilateral motor cortex maps, rats were trained to perform the isometric pull task, an automated motor task that requires skilled forelimb use. After either 3 or 6 months of training, intracortical microstimulation (ICMS) mapping was performed to document motor representations of the trained forelimb in the hemisphere ipsilateral to that limb. Motor training for 3 months resulted in a robust expansion of right forelimb representation in the right motor cortex, demonstrating that skilled motor training drives map plasticity ipsilateral to the trained limb. After 6 months of training, the right forelimb representation in the right motor cortex was significantly smaller than the representation observed in rats trained for 3 months and similar to untrained controls, consistent with a normalization of motor cortex maps. Forelimb map area was not correlated with performance on the trained task, suggesting that task performance is maintained despite normalization of cortical maps. This study provides new insights into how the ipsilateral cortex changes in response to skilled learning and may inform rehabilitative strategies to enhance cortical plasticity to support recovery after brain injury.

  4. Signals from the ventrolateral thalamus to the motor cortex during locomotion

    PubMed Central

    Marlinski, Vladimir; Nilaweera, Wijitha U.; Zelenin, Pavel V.; Sirota, Mikhail G.

    2012-01-01

    The activity of the motor cortex during locomotion is profoundly modulated in the rhythm of strides. The source of modulation is not known. In this study we examined the activity of one of the major sources of afferent input to the motor cortex, the ventrolateral thalamus (VL). Experiments were conducted in chronically implanted cats with an extracellular single-neuron recording technique. VL neurons projecting to the motor cortex were identified by antidromic responses. During locomotion, the activity of 92% of neurons was modulated in the rhythm of strides; 67% of cells discharged one activity burst per stride, a pattern typical for the motor cortex. The characteristics of these discharges in most VL neurons appeared to be well suited to contribute to the locomotion-related activity of the motor cortex. In addition to simple locomotion, we examined VL activity during walking on a horizontal ladder, a task that requires vision for correct foot placement. Upon transition from simple to ladder locomotion, the activity of most VL neurons exhibited the same changes that have been reported for the motor cortex, i.e., an increase in the strength of stride-related modulation and shortening of the discharge duration. Five modes of integration of simple and ladder locomotion-related information were recognized in the VL. We suggest that, in addition to contributing to the locomotion-related activity in the motor cortex during simple locomotion, the VL integrates and transmits signals needed for correct foot placement on a complex terrain to the motor cortex. PMID:21994259

  5. Motor cortex stimulation in Parkinson's disease.

    PubMed

    De Rose, Marisa; Guzzi, Giusy; Bosco, Domenico; Romano, Mary; Lavano, Serena Marianna; Plastino, Massimiliano; Volpentesta, Giorgio; Marotta, Rosa; Lavano, Angelo

    2012-01-01

    Motor Cortex Stimulation (MCS) is less efficacious than Deep Brain Stimulation (DBS) in Parkinson's disease. However, it might be proposed to patients excluded from DBS or unresponsive to DBS. Ten patients with advanced PD underwent unilateral MCS contralaterally to the worst clinical side. A plate electrode was positioned over the motor cortex in the epidural space through single burr hole after identification of the area with neuronavigation and neurophysiological tests. Clinical assessment was performed by total UPDRS, UPDRS III total, UPDRS III-items 27-31, UPDRS IV, and UPDRS II before implantation in off-medication and on-medication states and after surgery at 1, 3, 6, 12, 18, 24, and 36 months in on-medication/on-stimulation and off-medication/on-stimulation states. We assessed changes of quality of life, throughout the Parkinson's disease quality of life scale (PDQoL-39), and the dose of anti-Parkinson's disease medications, throughout the Ldopa equivalent daily dose (LEDD). During off-medication state, we observed moderate and transitory reduction of total UPDRS and UPDRS total scores and significant and long-lasting improvement in UPDRS III items 27-31 score for axial symptoms. There was marked reduction of UPDRS IV score and LEDD. PDQL-39 improvement was also significant. No important complications and adverse events occurred.

  6. Motor Cortex Stimulation in Parkinson's Disease

    PubMed Central

    De Rose, Marisa; Guzzi, Giusy; Bosco, Domenico; Romano, Mary; Lavano, Serena Marianna; Plastino, Massimiliano; Volpentesta, Giorgio; Marotta, Rosa; Lavano, Angelo

    2012-01-01

    Motor Cortex Stimulation (MCS) is less efficacious than Deep Brain Stimulation (DBS) in Parkinson's disease. However, it might be proposed to patients excluded from DBS or unresponsive to DBS. Ten patients with advanced PD underwent unilateral MCS contralaterally to the worst clinical side. A plate electrode was positioned over the motor cortex in the epidural space through single burr hole after identification of the area with neuronavigation and neurophysiological tests. Clinical assessment was performed by total UPDRS, UPDRS III total, UPDRS III-items 27–31, UPDRS IV, and UPDRS II before implantation in off-medication and on-medication states and after surgery at 1, 3, 6, 12, 18, 24, and 36 months in on-medication/on-stimulation and off-medication/on-stimulation states. We assessed changes of quality of life, throughout the Parkinson's disease quality of life scale (PDQoL-39), and the dose of anti-Parkinson's disease medications, throughout the Ldopa equivalent daily dose (LEDD). During off-medication state, we observed moderate and transitory reduction of total UPDRS and UPDRS total scores and significant and long-lasting improvement in UPDRS III items 27–31 score for axial symptoms. There was marked reduction of UPDRS IV score and LEDD. PDQL-39 improvement was also significant. No important complications and adverse events occurred. PMID:23213520

  7. Modulation of motor cortex inhibition during motor imagery.

    PubMed

    Chong, Benjamin W X; Stinear, Cathy M

    2017-04-01

    Motor imagery (MI) is similar to overt movement, engaging common neural substrates and facilitating the corticomotor pathway; however, it does not result in excitatory descending motor output. Transcranial magnetic stimulation (TMS) can be used to assess inhibitory networks in the primary motor cortex via measures of 1-ms short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and late cortical disinhibition (LCD). These measures are thought to reflect extrasynaptic GABAA tonic inhibition, postsynaptic GABAB inhibition, and presynaptic GABAB disinhibition, respectively. The behavior of 1-ms SICI, LICI, and LCD during MI has not yet been explored. This study aimed to investigate how 1-ms SICI, LICI, and LCD are modulated during MI and voluntary relaxation (VR) of a target muscle. Twenty-five healthy young adults participated. TMS was used to assess nonconditioned motor evoked potential (MEP) amplitude, 1-ms SICI, 100- (LICI100) and 150-ms LICI, and LCD in the right abductor pollicis brevis (APB) and right abductor digiti minimi during rest, MI, and VR of the hand. Compared with rest, MEP amplitudes were facilitated in APB during MI. SICI was not affected by task or muscle. LICI100 decreased in both muscles during VR but not MI, whereas LCD was recruited in both muscles during both tasks. This indicates that VR modulates postsynaptic GABAB inhibition, whereas both tasks modulate presynaptic GABAB inhibition in a non-muscle-specific way. This study highlights further neurophysiological parallels between actual and imagined movement, which may extend to voluntary relaxation.NEW & NOTEWORTHY This is the first study to investigate how 1-ms short-interval intracortical inhibition, long-interval intracortical inhibition, and late cortical disinhibition are modulated during motor imagery and voluntary muscle relaxation. We present novel findings of decreased 100-ms long-interval intracortical inhibition during voluntary muscle

  8. TOP-DOWN CONTROL OF MOTOR CORTEX ENSEMBLES BY DORSOMEDIAL PREFRONTAL CORTEX

    PubMed Central

    Narayanan, Nandakumar S.; Laubach, Mark

    2007-01-01

    SUMMARY Dorsomedial prefrontal cortex is critical for the temporal control of behavior. Dorsomedial prefrontal cortex might alter neuronal activity in areas such as motor cortex to inhibit temporally inappropriate responses. We tested this hypothesis by recording from neuronal ensembles in rodent dorsomedial prefrontal cortex during a delayed-response task. One-third of dorsomedial prefrontal neurons were significantly modulated during the delay period. The activity of many of these neurons was predictive of premature responding. We then reversibly inactivated dorsomedial prefrontal cortex while recording ensemble activity in motor cortex. Inactivation of dorsomedial prefrontal cortex reduced delay-related firing, but not response-related firing, in motor cortex. Finally, we made simultaneous recordings in dorsomedial prefrontal cortex and motor cortex and found strong delay-related temporal correlations between neurons in the two cortical areas. These data suggest that functional interactions between dorsomedial prefrontal cortex and motor cortex might serve as a top-down control signal that inhibits inappropriate responding. PMID:17145511

  9. Avalanche Analysis from Multielectrode Ensemble Recordings in Cat, Monkey, and Human Cerebral Cortex during Wakefulness and Sleep

    PubMed Central

    Dehghani, Nima; Hatsopoulos, Nicholas G.; Haga, Zach D.; Parker, Rebecca A.; Greger, Bradley; Halgren, Eric; Cash, Sydney S.; Destexhe, Alain

    2012-01-01

    Self-organized critical states are found in many natural systems, from earthquakes to forest fires, they have also been observed in neural systems, particularly, in neuronal cultures. However, the presence of critical states in the awake brain remains controversial. Here, we compared avalanche analyses performed on different in vivo preparations during wakefulness, slow-wave sleep, and REM sleep, using high density electrode arrays in cat motor cortex (96 electrodes), monkey motor cortex and premotor cortex and human temporal cortex (96 electrodes) in epileptic patients. In neuronal avalanches defined from units (up to 160 single units), the size of avalanches never clearly scaled as power-law, but rather scaled exponentially or displayed intermediate scaling. We also analyzed the dynamics of local field potentials (LFPs) and in particular LFP negative peaks (nLFPs) among the different electrodes (up to 96 sites in temporal cortex or up to 128 sites in adjacent motor and premotor cortices). In this case, the avalanches defined from nLFPs displayed power-law scaling in double logarithmic representations, as reported previously in monkey. However, avalanche defined as positive LFP (pLFP) peaks, which are less directly related to neuronal firing, also displayed apparent power-law scaling. Closer examination of this scaling using the more reliable cumulative distribution function (CDF) and other rigorous statistical measures, did not confirm power-law scaling. The same pattern was seen for cats, monkey, and human, as well as for different brain states of wakefulness and sleep. We also tested other alternative distributions. Multiple exponential fitting yielded optimal fits of the avalanche dynamics with bi-exponential distributions. Collectively, these results show no clear evidence for power-law scaling or self-organized critical states in the awake and sleeping brain of mammals, from cat to man. PMID:22934053

  10. Motor cortex activity predicts response alternation during sensorimotor decisions

    PubMed Central

    Pape, Anna-Antonia; Siegel, Markus

    2016-01-01

    Our actions are constantly guided by decisions based on sensory information. The motor cortex is traditionally viewed as the final output stage in this process, merely executing motor responses based on these decisions. However, it is not clear if, beyond this role, the motor cortex itself impacts response selection. Here, we report activity fluctuations over motor cortex measured using MEG, which are unrelated to choice content and predict responses to a visuomotor task seconds before decisions are made. These fluctuations are strongly influenced by the previous trial's response and predict a tendency to switch between response alternatives for consecutive decisions. This alternation behaviour depends on the size of neural signals still present from the previous response. Our results uncover a response-alternation bias in sensorimotor decision making. Furthermore, they suggest that motor cortex is more than an output stage and instead shapes response selection during sensorimotor decision making. PMID:27713396

  11. The Laryngeal Motor Cortex: Its Organization and Connectivity

    PubMed Central

    Simonyan, Kristina

    2014-01-01

    Our ability to learn and control the motor aspects of complex laryngeal behaviors, such as speech and song, is modulated by the laryngeal motor cortex (LMC), which is situated in the area 4 of the primary motor cortex and establishes both direct and indirect connections with laryngeal motoneurons. In contrast, the LMC in monkeys is located in the area 6 of the premotor cortex, projects only indirectly to laryngeal motoneurons and its destruction has essentially no effect on production of species-specific calls. These differences in cytoarchitectonic location and connectivity may be a result of hominid evolution that led to the LMC shift from the phylogenetically “old” to “new” motor cortex in order to fulfill its paramount function, i.e., voluntary motor control of human speech and song production. PMID:24929930

  12. Multiple dynamic representations in the motor cortex during sensorimotor learning.

    PubMed

    Huber, D; Gutnisky, D A; Peron, S; O'Connor, D H; Wiegert, J S; Tian, L; Oertner, T G; Looger, L L; Svoboda, K

    2012-04-25

    The mechanisms linking sensation and action during learning are poorly understood. Layer 2/3 neurons in the motor cortex might participate in sensorimotor integration and learning; they receive input from sensory cortex and excite deep layer neurons, which control movement. Here we imaged activity in the same set of layer 2/3 neurons in the motor cortex over weeks, while mice learned to detect objects with their whiskers and report detection with licking. Spatially intermingled neurons represented sensory (touch) and motor behaviours (whisker movements and licking). With learning, the population-level representation of task-related licking strengthened. In trained mice, population-level representations were redundant and stable, despite dynamism of single-neuron representations. The activity of a subpopulation of neurons was consistent with touch driving licking behaviour. Our results suggest that ensembles of motor cortex neurons couple sensory input to multiple, related motor programs during learning.

  13. The laryngeal motor cortex: its organization and connectivity.

    PubMed

    Simonyan, Kristina

    2014-10-01

    Our ability to learn and control the motor aspects of complex laryngeal behaviors, such as speech and song, is modulated by the laryngeal motor cortex (LMC), which is situated in the area 4 of the primary motor cortex and establishes both direct and indirect connections with laryngeal motoneurons. In contrast, the LMC in monkeys is located in the area 6 of the premotor cortex, projects only indirectly to laryngeal motoneurons and its destruction has essentially no effect on production of species-specific calls. These differences in cytoarchitectonic location and connectivity may be a result of hominid evolution that led to the LMC shift from the phylogenetically 'old' to 'new' motor cortex in order to fulfill its paramount function, that is, voluntary motor control of human speech and song production.

  14. Unit responses of the secondary somatosensory cortex during defensive conditioning in cats.

    PubMed

    Kruchenko, Z A; Taran, G A

    1980-01-01

    Unit responses in the secondary somatosensory cortex during the formation and extinction of a defensive conditioned reflex to acoustic stimulation were investigated in chronic experiments on cats. In 21 of 28 neurons tested during defensive conditioning the firing pattern changed in accordance with the character of responses to electric shock reinforcement. Two types of conditioned-reflex unit responses were distinguished: excitatory and inhibitory. Most neurons responding to the conditioned stimulus by activation did so during the first 50 msec, which was 80-100 msec before the conditioned motor response. Considerable variability of the unit responses was observed during conditioning. By the time of stabilization of the conditioned-reflex connections the unit response to the conditioned stimulus was stable in form. The pattern of extinction of the conditioned unit activity was expressed as a decrease in the discharge frequency in responses of excitatory type and disinhibition of activity in the case of inhibitory responses.

  15. [Functional asymmetry of the frontal cortex and lateral hypothalamus of cats during food instrumental conditioning].

    PubMed

    Vanetsiian, G L; Pavlova, I V

    2003-01-01

    The synchronism and latency of auditory evoked potentials (EP) recorded in symmetric points of the frontal cortex and lateral hypothalamus of cats were measured at different stages of instrumental food conditioning and after the urgent transition to 30% reinforcement. Correlation coefficients between EPs in the cortex and hypothalamus were high (with left-side dominance) at the beginning of the experiments, when food motivation was high, and during the whole experiments in cases of high-probability of conditioned performance. Analysis of early positive P55-80 EP component showed that at all conditioning stages the peak latency of this component was shorter in the left cortical areas than in symmetrical points, whereas in the hypothalamus the shorter latency at the left side was observed at the stage of unstable conditioned reflex, and at the stage of stable reflex the latency of the studied component was shorter at the right side. During transition to 30% reinforcement, the latency was also shorter in the right hypothalamus. It is suggested that the high left-side correlation between the hypothalamus and cortex was associated with motivational and motor component of behavior rather than reflected the emotional stress induced by transition to another stereotype of food reinforcement (30%).

  16. Stimulating the lip motor cortex with transcranial magnetic stimulation.

    PubMed

    Möttönen, Riikka; Rogers, Jack; Watkins, Kate E

    2014-06-14

    Transcranial magnetic stimulation (TMS) has proven to be a useful tool in investigating the role of the articulatory motor cortex in speech perception. Researchers have used single-pulse and repetitive TMS to stimulate the lip representation in the motor cortex. The excitability of the lip motor representation can be investigated by applying single TMS pulses over this cortical area and recording TMS-induced motor evoked potentials (MEPs) via electrodes attached to the lip muscles (electromyography; EMG). Larger MEPs reflect increased cortical excitability. Studies have shown that excitability increases during listening to speech as well as during viewing speech-related movements. TMS can be used also to disrupt the lip motor representation. A 15-min train of low-frequency sub-threshold repetitive stimulation has been shown to suppress motor excitability for a further 15-20 min. This TMS-induced disruption of the motor lip representation impairs subsequent performance in demanding speech perception tasks and modulates auditory-cortex responses to speech sounds. These findings are consistent with the suggestion that the motor cortex contributes to speech perception. This article describes how to localize the lip representation in the motor cortex and how to define the appropriate stimulation intensity for carrying out both single-pulse and repetitive TMS experiments.

  17. The auditory representation of speech sounds in human motor cortex

    PubMed Central

    Cheung, Connie; Hamilton, Liberty S; Johnson, Keith; Chang, Edward F

    2016-01-01

    In humans, listening to speech evokes neural responses in the motor cortex. This has been controversially interpreted as evidence that speech sounds are processed as articulatory gestures. However, it is unclear what information is actually encoded by such neural activity. We used high-density direct human cortical recordings while participants spoke and listened to speech sounds. Motor cortex neural patterns during listening were substantially different than during articulation of the same sounds. During listening, we observed neural activity in the superior and inferior regions of ventral motor cortex. During speaking, responses were distributed throughout somatotopic representations of speech articulators in motor cortex. The structure of responses in motor cortex during listening was organized along acoustic features similar to auditory cortex, rather than along articulatory features as during speaking. Motor cortex does not contain articulatory representations of perceived actions in speech, but rather, represents auditory vocal information. DOI: http://dx.doi.org/10.7554/eLife.12577.001 PMID:26943778

  18. Body stability and muscle and motor cortex activity during walking with wide stance

    PubMed Central

    Farrell, Brad J.; Bulgakova, Margarita A.; Beloozerova, Irina N.; Sirota, Mikhail G.

    2014-01-01

    Biomechanical and neural mechanisms of balance control during walking are still poorly understood. In this study, we examined the body dynamic stability, activity of limb muscles, and activity of motor cortex neurons [primarily pyramidal tract neurons (PTNs)] in the cat during unconstrained walking and walking with a wide base of support (wide-stance walking). By recording three-dimensional full-body kinematics we found for the first time that during unconstrained walking the cat is dynamically unstable in the forward direction during stride phases when only two diagonal limbs support the body. In contrast to standing, an increased lateral between-paw distance during walking dramatically decreased the cat's body dynamic stability in double-support phases and prompted the cat to spend more time in three-legged support phases. Muscles contributing to abduction-adduction actions had higher activity during stance, while flexor muscles had higher activity during swing of wide-stance walking. The overwhelming majority of neurons in layer V of the motor cortex, 82% and 83% in the forelimb and hindlimb representation areas, respectively, were active differently during wide-stance walking compared with unconstrained condition, most often by having a different depth of stride-related frequency modulation along with a different mean discharge rate and/or preferred activity phase. Upon transition from unconstrained to wide-stance walking, proximal limb-related neuronal groups subtly but statistically significantly shifted their activity toward the swing phase, the stride phase where most of body instability occurs during this task. The data suggest that the motor cortex participates in maintenance of body dynamic stability during locomotion. PMID:24790167

  19. Primary Motor Cortex Involvement in Initial Learning during Visuomotor Adaptation

    ERIC Educational Resources Information Center

    Riek, Stephan; Hinder, Mark R.; Carson, Richard G.

    2012-01-01

    Human motor behaviour is continually modified on the basis of errors between desired and actual movement outcomes. It is emerging that the role played by the primary motor cortex (M1) in this process is contingent upon a variety of factors, including the nature of the task being performed, and the stage of learning. Here we used repetitive TMS to…

  20. Physiological characterization of motor unit properties in intact cats.

    PubMed

    O'Donovan, M J; Hoffer, J A; Loeb, G E

    1983-02-01

    Single motor units were isolated in intact cats, by microstimulation through chronically implanted microwires in the L5 ventral roots. Motor unit axonal and mechanical properties were obtained by stimulus-triggered averaging the signals from an implanted femoral nerve recording cuff and patellar tendon force transducer. All unit types were sampled with this technique, and it was also possible to stimulate in isolation an axon whose ventral root spike was recorded during treadmill locomotion. A new technique was described, spike-triggered microstimulation, for verifying the identity of a stimulated and a recorded axon.

  1. Dissociation of visual and auditory pattern discrimination functions within the cat's temporal cortex.

    PubMed

    Cornwell, P; Nudo, R J; Straussfogel, D; Lomber, S G; Payne, B R

    1998-08-01

    In ablation-behavior experiments performed in adult cats, a double dissociation was demonstrated between ventral posterior suprasylvian cortex (vPS) and temporo-insular cortex (TI) lesions on complex visual and auditory tasks. Lesions of the vPS cortex resulted in deficits at visual pattern discrimination, but not at a difficult auditory discrimination. By contrast, TI lesions resulted in profound deficits at discriminating complex sounds, but not at discriminating visual patterns. This pattern of dissociation of deficits in cats parallels the dissociation of deficits after inferior temporal versus superior temporal lesions in monkeys and humans.

  2. Similarities between GCS and human motor cortex: complex movement coordination

    NASA Astrophysics Data System (ADS)

    Rodríguez, Jose A.; Macias, Rosa; Molgo, Jordi; Guerra, Dailos

    2014-07-01

    The "Gran Telescopio de Canarias" (GTC1) is an optical-infrared 10-meter segmented mirror telescope at the ORM observatory in Canary Islands (Spain). The GTC control system (GCS), the brain of the telescope, is is a distributed object & component oriented system based on RT-CORBA and it is responsible for the management and operation of the telescope, including its instrumentation. On the other hand, the Human motor cortex (HMC) is a region of the cerebrum responsible for the coordination of planning, control, and executing voluntary movements. If we analyze both systems, as far as the movement control of their mechanisms and body parts is concerned, we can find extraordinary similarities in their architectures. Both are structured in layers, and their functionalities are comparable from the movement conception until the movement action itself: In the GCS we can enumerate the Sequencer high level components, the Coordination libraries, the Control Kit library and the Device Driver library as the subsystems involved in the telescope movement control. If we look at the motor cortex, we can also enumerate the primary motor cortex, the secondary motor cortices, which include the posterior parietal cortex, the premotor cortex, and the supplementary motor area (SMA), the motor units, the sensory organs and the basal ganglia. From all these components/areas we will analyze in depth the several subcortical regions, of the the motor cortex, that are involved in organizing motor programs for complex movements and the GCS coordination framework, which is composed by a set of classes that allow to the high level components to transparently control a group of mechanisms simultaneously.

  3. Impairments in prehension produced by early postnatal sensory motor cortex activity blockade.

    PubMed

    Martin, J H; Donarummo, L; Hacking, A

    2000-02-01

    This study examined the effects of blocking neural activity in sensory motor cortex during early postnatal development on prehension. We infused muscimol, either unilaterally or bilaterally, into the sensory motor cortex of cats to block activity continuously between postnatal weeks 3-7. After stopping infusion, we trained animals to reach and grasp a cube of meat and tested behavior thereafter. Animals that had not received muscimol infusion (unilateral saline infusion; age-matched) reached for the meat accurately with small end-point errors. They grasped the meat using coordinated digit flexion followed by forearm supination on 82.7% of trials. Performance using either limb did not differ significantly. In animals receiving unilateral muscimol infusion, reaching and grasping using the limb ipsilateral to the infusion were similar to controls. The limb contralateral to infusion showed significant increases in systematic and variable reaching end-point errors, often requiring subsequent corrective movements to contact the meat. Grasping occurred on only 14.8% of trials, replaced on most trials by raking without distal movements. Compensatory adjustments in reach length and angle, to maintain end-point accuracy as movements were started from a more lateral position, were less effective using the contralateral limb than ipsilateral limb. With bilateral inactivations, the form of reaching and grasping impairments was identical to that produced by unilateral inactivation, but the magnitude of the reaching impairments was less. We discuss these results in terms of the differential effects of unilateral and bilateral inactivation on corticospinal tract development. We also investigated the degree to which these prehension impairments after unilateral blockade reflect control by each hemisphere. In animals that had received unilateral blockade between postnatal weeks (PWs) 3 and 7, we silenced on-going activity (after PW 11) during task performance using continuous

  4. Motor cortex hyperexcitability to transcranial magnetic stimulation in Alzheimer's disease

    PubMed Central

    Di, L; Oliviero, A; Pilato, F; Saturno, E; Dileone, M; Marra, C; Daniele, A; Ghirlanda, S; Gainotti, G; Tonali, P

    2004-01-01

    Objectives: Recent transcranial magnetic stimulation (TMS) studies demonstrate that motor cortex excitability is increased in Alzheimer's disease (AD) and that intracortical inhibitory phenomena are impaired. The aim of the present study was to determine whether hyperexcitability is due to the impairment of intracortical inhibitory circuits or to an independent abnormality of excitatory circuits. Methods: We assessed the excitability of the motor cortex with TMS in 28 patients with AD using several TMS paradigms and compared the data of cortical excitability (evaluated by measuring resting motor threshold) with the amount of motor cortex disinhibition as evaluated using the test for motor cortex cholinergic inhibition (short latency afferent inhibition) and GABAergic inhibition (short latency intracortical inhibition). The data in AD patients were also compared with that from 12 age matched healthy individuals. Results: The mean resting motor threshold was significantly lower in AD patients than in controls. The amount of short latency afferent inhibition was significantly smaller in AD patients than in normal controls. There was also a tendency for AD patients to have less pronounced short latency intracortical inhibition than controls, but this difference was not significant. There was no correlation between resting motor threshold and measures of either short latency afferent or intracortical inhibition (r = -0.19 and 0.18 respectively, NS). In 14 AD patients the electrophysiological study was repeated after a single oral dose of the cholinesterase inhibitor rivastigmine. Resting motor threshold was not significantly modified by the administration of rivastigmine. In contrast, short latency afferent inhibition from the median nerve was significantly increased by the administration of rivastigmine. Conclusions: The change in threshold did not seem to correlate with dysfunction of inhibitory intracortical cholinergic and GABAergic circuits, nor with the central

  5. Repetitive Transcranial Magnetic Stimulation to the Primary Motor Cortex Interferes with Motor Learning by Observing

    ERIC Educational Resources Information Center

    Brown, Liana E.; Wilson, Elizabeth T.; Gribble, Paul L.

    2009-01-01

    Neural representations of novel motor skills can be acquired through visual observation. We used repetitive transcranial magnetic stimulation (rTMS) to test the idea that this "motor learning by observing" is based on engagement of neural processes for learning in the primary motor cortex (M1). Human subjects who observed another person learning…

  6. Seeing fearful body language rapidly freezes the observer's motor cortex.

    PubMed

    Borgomaneri, Sara; Vitale, Francesca; Gazzola, Valeria; Avenanti, Alessio

    2015-04-01

    Fearful body language is a salient signal alerting the observer to the presence of a potential threat in the surrounding environment. Although detecting potential threats may trigger an immediate reduction of motor output in animals (i.e., freezing behavior), it is unclear at what point in time similar reductions occur in the human motor cortex and whether they originate from excitatory or inhibitory processes. Using single-pulse and paired-pulse transcranial magnetic stimulation (TMS), here we tested the hypothesis that the observer's motor cortex implements extremely fast suppression of motor readiness when seeing emotional bodies - and fearful body expressions in particular. Participants observed pictures of body postures and categorized them as happy, fearful or neutral while receiving TMS over the right or left motor cortex at 100-125 msec after picture onset. In three different sessions, we assessed corticospinal excitability, short intracortical inhibition (SICI) and intracortical facilitation (ICF). Independently of the stimulated hemisphere and the time of the stimulation, watching fearful bodies suppressed ICF relative to happy and neutral body expressions. Moreover, happy expressions reduced ICF relative to neutral actions. No changes in corticospinal excitability or SICI were found during the task. These findings show extremely rapid bilateral modulation of the motor cortices when seeing emotional bodies, with stronger suppression of motor readiness when seeing fearful bodies. Our results provide neurophysiological support for the evolutionary notions that emotion perception is inherently linked to action systems and that fear-related cues induce an urgent mobilization of motor reactions.

  7. Transcranial static magnetic field stimulation of the human motor cortex.

    PubMed

    Oliviero, Antonio; Mordillo-Mateos, Laura; Arias, Pablo; Panyavin, Ivan; Foffani, Guglielmo; Aguilar, Juan

    2011-10-15

    The aim of the present study was to investigate in healthy humans the possibility of a non-invasive modulation of motor cortex excitability by the application of static magnetic fields through the scalp. Static magnetic fields were obtained by using cylindrical NdFeB magnets. We performed four sets of experiments. In Experiment 1, we recorded motor potentials evoked by single-pulse transcranial magnetic stimulation (TMS) of the motor cortex before and after 10 min of transcranial static magnetic field stimulation (tSMS) in conscious subjects. We observed an average reduction of motor cortex excitability of up to 25%, as revealed by TMS, which lasted for several minutes after the end of tSMS, and was dose dependent (intensity of the magnetic field) but not polarity dependent. In Experiment 2, we confirmed the reduction of motor cortex excitability induced by tSMS using a double-blind sham-controlled design. In Experiment 3, we investigated the duration of tSMS that was necessary to modulate motor cortex excitability. We found that 10 min of tSMS (compared to 1 min and 5 min) were necessary to induce significant effects. In Experiment 4, we used transcranial electric stimulation (TES) to establish that the tSMS-induced reduction of motor cortex excitability was not due to corticospinal axon and/or spinal excitability, but specifically involved intracortical networks. These results suggest that tSMS using small static magnets may be a promising tool to modulate cerebral excitability in a non-invasive, painless, and reversible way.

  8. [A histochemical study of acetylcholinesterase in intact and deafferented cat auditory cortex].

    PubMed

    Genis, E D

    1976-01-01

    The peculiarities of the AChE distribution were investigated in the intact cat auditory cortex and during early period of its neuronal isolation. It is shown that in the isolated cortex slab the staining of the AChE containing fibre disappeared from the neuropile, while in the intact cortex it was well pronounced. AChE accumulation was observed in the proximal parts of the transsected thalamo-cortical fibres. It is supposed that the AChE-containing fibres in the auditory cortex belong to nonspecific thalamic inputs.

  9. Primary somatosensory cortex hand representation dynamically modulated by motor output.

    PubMed

    McGeoch, Paul D; Brang, David; Huang, Mingxiong; Ramachandran, V S

    2015-02-01

    The brain's primary motor and primary somatosensory cortices are generally viewed as functionally distinct entities. Here we show by means of magnetoencephalography with a phantom-limb patient, that movement of the phantom hand leads to a change in the response of the primary somatosensory cortex to tactile stimulation. This change correlates with the described conscious perception and suggests a greater degree of functional unification between the primary motor and somatosensory cortices than is currently realized. We suggest that this may reflect the evolution of this part of the human brain, which is thought to have occurred from an undifferentiated sensorimotor cortex.

  10. Long-term motor cortex stimulation for phantom limb pain.

    PubMed

    Pereira, Erlick A C; Moore, Tom; Moir, Liz; Aziz, Tipu Z

    2015-04-01

    We present the long-term course of motor cortex stimulation to relieve a case of severe burning phantom arm pain after brachial plexus injury and amputation. During 16-year follow-up the device continued to provide efficacious analgesia. However, several adjustments of stimulation parameters were required, as were multiple pulse generator changes, antibiotics for infection and one electrode revision due to lead migration. Steady increases in stimulation parameters over time were required. One of the longest follow-ups of motor cortex stimulation is described; the case illustrates challenges and pitfalls in neuromodulation for chronic pain, demonstrating strategies for maintaining analgesia and overcoming tolerance.

  11. The role of the premotor cortex and the primary motor cortex in action verb comprehension: evidence from Granger causality analysis.

    PubMed

    Yang, Jie; Shu, Hua

    2012-08-01

    Although numerous studies find the premotor cortex and the primary motor cortex are involved in action language comprehension, so far the nature of these motor effects is still in controversy. Some researchers suggest that the motor effects reflect that the premotor cortex and the primary motor cortex make functional contributions to the semantic access of action verbs, while other authors argue that the motor effects are caused by comprehension. In the current study, we used Granger causality analysis to investigate the roles of the premotor cortex and the primary motor cortex in processing of manual-action verbs. Regions of interest were selected in the primary motor cortex (M1) and the premotor cortex based on a hand motion task, and in the left posterior middle temporal gyrus (lexical semantic area) based on the reading task effect. We found that (1) the left posterior middle temporal gyrus had a causal influence on the left M1; and (2) the left posterior middle temporal gyrus and the left premotor cortex had bidirectional causal relations. These results suggest that the premotor cortex and the primary motor cortex play different roles in manual verb comprehension. The premotor cortex may be involved in motor simulation that contributes to action language processing, while the primary motor cortex may be engaged in a processing stage influenced by the meaning access of manual-action verbs. Further investigation combining effective connectivity analysis and technique with high temporal resolution is necessary for better clarification of the roles of the premotor cortex and the primary motor cortex in action language comprehension.

  12. A little more conversation, a little less action - candidate roles for motor cortex in speech perception

    PubMed Central

    Scott, Sophie K; McGettigan, Carolyn; Eisner, Frank

    2014-01-01

    The motor theory of speech perception assumes that activation of the motor system is essential in the perception of speech. However, deficits in speech perception and comprehension do not arise from damage that is restricted to the motor cortex, few functional imaging studies reveal activity in motor cortex during speech perception, and the motor cortex is strongly activated by many different sound categories. Here, we evaluate alternative roles for the motor cortex in spoken communication and suggest a specific role in sensorimotor processing in conversation. We argue that motor-cortex activation it is essential in joint speech, particularly for the timing of turn-taking. PMID:19277052

  13. Motor learning in animal models of Parkinson's disease: Aberrant synaptic plasticity in the motor cortex.

    PubMed

    Xu, Tonghui; Wang, Shaofang; Lalchandani, Rupa R; Ding, Jun B

    2017-03-25

    In Parkinson's disease (PD), dopamine depletion causes major changes in the brain, resulting in the typical cardinal motor features of the disease. PD neuropathology has been restricted to postmortem examinations, which are limited to only a single time of PD progression. Models of PD in which dopamine tone in the brain is chemically or physically disrupted are valuable tools in understanding the mechanisms of the disease. The basal ganglia have been well studied in the context of PD, and circuit changes in response to dopamine loss have been linked to the motor dysfunctions in PD. However, the etiology of the cognitive dysfunctions that are comorbid in PD patients has remained unclear until now. In this article, we review recent studies exploring how dopamine depletion affects the motor cortex at the synaptic level. In particular, we highlight our recent findings on abnormal spine dynamics in the motor cortex of PD mouse models through in vivo time-lapse imaging and motor skill behavior assays. In combination with previous studies, a role of the motor cortex in skill learning and the impairment of this ability with the loss of dopamine are becoming more apparent. Taken together, we conclude with a discussion on the potential role for the motor cortex in PD, with the possibility of targeting the motor cortex for future PD therapeutics. © 2017 International Parkinson and Movement Disorder Society.

  14. Transcranial direct current stimulation of the motor cortex in waking resting state induces motor imagery.

    PubMed

    Speth, Jana; Speth, Clemens; Harley, Trevor A

    2015-11-01

    This study investigates if anodal and cathodal transcranial direct current stimulation (tDCS) of areas above the motor cortex (C3) influences spontaneous motor imagery experienced in the waking resting state. A randomized triple-blinded design was used, combining neurophysiological techniques with tools of quantitative mentation report analysis from cognitive linguistics. The results indicate that while spontaneous motor imagery rarely occurs under sham stimulation, general and athletic motor imagery (classified as athletic disciplines), is induced by anodal tDCS. This insight may have implications beyond basic consciousness research. Motor imagery and corresponding motor cortical activation have been shown to benefit later motor performance. Electrophysiological manipulations of motor imagery could in the long run be used for rehabilitative tDCS protocols benefitting temporarily immobile clinical patients who cannot perform specific motor imagery tasks - such as dementia patients, infants with developmental and motor disorders, and coma patients.

  15. Parietal transcranial direct current stimulation modulates primary motor cortex excitability.

    PubMed

    Rivera-Urbina, Guadalupe Nathzidy; Batsikadze, Giorgi; Molero-Chamizo, Andrés; Paulus, Walter; Kuo, Min-Fang; Nitsche, Michael A

    2015-03-01

    The posterior parietal cortex is part of the cortical network involved in motor learning and is structurally and functionally connected with the primary motor cortex (M1). Neuroplastic alterations of neuronal connectivity might be an important basis for learning processes. These have however not been explored for parieto-motor connections in humans by transcranial direct current stimulation (tDCS). Exploring tDCS effects on parieto-motor cortical connectivity might be functionally relevant, because tDCS has been shown to improve motor learning. We aimed to explore plastic alterations of parieto-motor cortical connections by tDCS in healthy humans. We measured neuroplastic changes of corticospinal excitability via motor evoked potentials (MEP) elicited by single-pulse transcranial magnetic stimulation (TMS) before and after tDCS over the left posterior parietal cortex (P3), and 3 cm posterior or lateral to P3, to explore the spatial specificity of the effects. Furthermore, short-interval intracortical inhibition/intracortical facilitation (SICI/ICF) over M1, and parieto-motor cortical connectivity were obtained before and after P3 tDCS. The results show polarity-dependent M1 excitability alterations primarily after P3 tDCS. Single-pulse TMS-elicited MEPs, M1 SICI/ICF at 5 and 7 ms and 10 and 15 ms interstimulus intervals (ISIs), and parieto-motor connectivity at 10 and 15 ms ISIs were all enhanced by anodal stimulation. Single pulse-TMS-elicited MEPs, and parieto-motor connectivity at 10 and 15 ms ISIs were reduced by cathodal tDCS. The respective corticospinal excitability alterations lasted for at least 120 min after stimulation. These results show an effect of remote stimulation of parietal areas on M1 excitability. The spatial specificity of the effects and the impact on parietal cortex-motor cortex connections suggest a relevant connectivity-driven effect.

  16. Projection from the perirhinal cortex to the frontal motor cortex in the rat.

    PubMed

    Kyuhou, Shin ichi; Gemba, Hisae

    2002-03-01

    Stimulation of the anterior perirhinal cortex (PERa) induced marked surface-negative and depth-positive field potentials in the rat frontal motor cortex (MC) including the rostral and caudal forelimb areas. Injection of biotinylated dextran into the PERa densely labeled axon terminals in the superficial layers of the MC, where vigorous unit responses were evoked after PERa stimulation, indicated that the perirhinal-frontal projection preferentially activates the superficial layer neurons of the MC.

  17. Cancellation of a planned movement in monkey motor cortex.

    PubMed

    Riehle, Alexa; Grammont, Franck; MacKay, William A

    2006-02-27

    Abruptly stopping a planned movement before it has even begun can be crucial to retarding a premature action. In the monkey motor cortex, we report herein that rapid cancellation of a prepared motor act involved the brief activation of neurons representing a movement in the opposite direction (anti-directional activity). When an expected GO signal failed to occur, this opposing anti-directional discharge appeared. It coincided in time with the cessation of the motor cortical activity preparing the requested arm reach. We suggest that functional interactions between subpopulations of neurons eliciting movements in opposite directions could rapidly alter population dynamics, and therefore be used to abruptly cancel a planned movement.

  18. Modification of motor cortex excitability during muscle relaxation in motor learning.

    PubMed

    Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Saitoh, Kei; Higashi, Toshio

    2016-01-01

    We postulated that gradual muscle relaxation during motor learning would dynamically change activity in the primary motor cortex (M1) and modify short-interval intracortical inhibition (SICI). Thus, we compared changes in M1 excitability both pre and post motor learning during gradual muscle relaxation. Thirteen healthy participants were asked to gradually relax their muscles from an isometric right wrist extension (30% maximum voluntary contraction; MVC) using a tracking task for motor learning. Single or paired transcranial magnetic stimulation (TMS) was applied at either 20% or 80% of the downward force output during muscle release from 30% MVC, and we compared the effects of motor learning immediately after the 1st and 10th blocks. Motor-evoked potentials (MEPs) from the extensor and flexor carpi radialis (ECR and FCR) were then measured and compared to evaluate their relationship before and after motor learning. In both muscles and each downward force output, motor cortex excitability during muscle relaxation was significantly increased following motor learning. In the ECR, the SICI in the 10th block was significantly increased during the 80% waveform decline compared to the SICI in the 1st block. In the FCR, the SICI also exhibited a greater inhibitory effect when muscle relaxation was terminated following motor learning. During motor training, acquisition of the ability to control muscle relaxation increased the SICI in both the ECR and FCR during motor termination. This finding aids in our understanding of the cortical mechanisms that underlie muscle relaxation during motor learning.

  19. Dopamine Promotes Motor Cortex Plasticity and Motor Skill Learning via PLC Activation.

    PubMed

    Rioult-Pedotti, Mengia-Seraina; Pekanovic, Ana; Atiemo, Clement Osei; Marshall, John; Luft, Andreas Rüdiger

    2015-01-01

    Dopaminergic neurons in the ventral tegmental area, the major midbrain nucleus projecting to the motor cortex, play a key role in motor skill learning and motor cortex synaptic plasticity. Dopamine D1 and D2 receptor antagonists exert parallel effects in the motor system: they impair motor skill learning and reduce long-term potentiation. Traditionally, D1 and D2 receptor modulate adenylyl cyclase activity and cyclic adenosine monophosphate accumulation in opposite directions via different G-proteins and bidirectionally modulate protein kinase A (PKA), leading to distinct physiological and behavioral effects. Here we show that D1 and D2 receptor activity influences motor skill acquisition and long term synaptic potentiation via phospholipase C (PLC) activation in rat primary motor cortex. Learning a new forelimb reaching task is severely impaired in the presence of PLC, but not PKA-inhibitor. Similarly, long term potentiation in motor cortex, a mechanism involved in motor skill learning, is reduced when PLC is inhibited but remains unaffected by the PKA inhibitor. Skill learning deficits and reduced synaptic plasticity caused by dopamine antagonists are prevented by co-administration of a PLC agonist. These results provide evidence for a role of intracellular PLC signaling in motor skill learning and associated cortical synaptic plasticity, challenging the traditional view of bidirectional modulation of PKA by D1 and D2 receptors. These findings reveal a novel and important action of dopamine in motor cortex that might be a future target for selective therapeutic interventions to support learning and recovery of movement resulting from injury and disease.

  20. Primary motor cortex activity is elevated with incremental exercise intensity.

    PubMed

    Brümmer, V; Schneider, S; Strüder, H K; Askew, C D

    2011-05-05

    While the effects of exercise on brain cortical activity from pre-to post-exercise have been thoroughly evaluated, few studies have investigated the change in activity during exercise. As such, it is not clear to what extent changes in exercise intensity influence brain cortical activity. Furthermore, due to the difficulty in using brain-imaging methods during complex whole-body movements like cycling, it is unclear to what extent the activity in specific brain areas is altered with incremental exercise intensity over time. Latterly, active electroencephalography (EEG) electrodes combined with source localization methods allow for the assessment of brain activity, measured as EEG current density, within specific cortical regions. The present study aimed to investigate the application of this method during exercise on a cycle ergometer, and to investigate the effect of increasing exercise intensity on the magnitude and location of any changes in electrocortical current density. Subjects performed an incremental cycle ergometer test until subjective exhaustion. Current density of the EEG recordings during each test stage, as well as before and after exercise, was determined. Spatial changes in current density were localized using low-resolution brain electromagnetic tomography (LORETA) to three regions of interest; the primary motor cortex, primary sensory cortex and prefrontal cortex, and were expressed relative to current density within the local lobe. It was demonstrated that the relative current density of the primary motor cortex was intensified with increasing exercise intensity, whereas activity of the primary sensory cortex and that of the prefrontal cortex were not altered with exercise. The results indicate that the combined active EEG/LORETA method allows for the recording of brain cortical activity during complex movements and incremental exercise. These findings indicate that primary motor cortex activity is elevated with incremental exercise intensity

  1. Reorganization of human motor cortex after hand replantation.

    PubMed

    Röricht, S; Machetanz, J; Irlbacher, K; Niehaus, L; Biemer, E; Meyer, B U

    2001-08-01

    In 10 patients, reorganizational changes of the motor cortex contralateral to a replanted hand (MCreplant) were studied one to 14 years after complete traumatic amputation and consecutive successful replantation of the hand. The organizational state of MCreplant was assessed for the deafferentated and peripherally deefferentated hand-associated motor cortex and the adjacent motor representation of the proximal arm. For this, response maps were established for the first dorsal interosseus and biceps brachii muscle using focal transcranial magnetic stimulation (TMS) on a skull surface grid. Characteristics of the maps were center of gravity (COG), number of effective stimulation sites, amplitude sum, and amplitudes and response threshold at the optimal stimulation point. The COG is defined by the spatial distribution of response amplitudes on the map and lies over the cortex region with the most excitable corticospinal neurones supplying the recorded muscle. The COG of the biceps map in MCreplant was shifted laterally by 9.8 +/- 3.6 mm (range 5.0-15.7 mm). The extension of the biceps map in MCreplant was increased and the responses were enlarged and had lowered thresholds. For the muscles of the replanted hand, the pattern of reorganization was different: Response amplitudes were enlarged but thresholds, COG, and area of the cortical response map were normal. The different reorganizational phenomena observed for the motor cortical areas supplying the replanted hand and the biceps brachii of the same arm may be influenced by a different extent of deafferentation and by their different role in hand motor control.

  2. Motor Cortex Inhibition is Increased During a Secondary Cognitive Task.

    PubMed

    Holste, Katherine G; Yasen, Alia L; Hill, Matthew J; Christie, Anita D

    2016-10-01

    The purpose of this study was to assess the effect of a cognitive task on motor cortex excitability and inhibition. Transcranial magnetic stimulation of the motor cortex was performed on 20 healthy individuals (18-24 years; 9 females) to measure motor evoked potentials (MEPs) and cortical silent periods at baseline, during, and following a secondary cognitive task. The MEP amplitude increased from 0.50 ± 0.09-0.87 ± 0.50 mV during a secondary cognitive task (p = .04), and returned to baseline (0.48 ± 0.31 mV; p = .90) posttask. The CSP duration also increased from 93.48 ± 28.76-113.6 ± 33.68 ms (p = .001) during the cognitive task, and returned to baseline posttask (89.0 ± 6.9 ms; p = .88). In the presence of a cognitive task, motor cortex excitability and inhibition were both increased relative to baseline. The increase in inhibition may help to explain the motor deficits experienced while performing a secondary cognitive task.

  3. Robust neuronal dynamics in premotor cortex during motor planning

    PubMed Central

    Li, Nuo; Daie, Kayvon; Svoboda, Karel; Druckmann, Shaul

    2016-01-01

    Neural activity maintains representations that bridge past and future events, often over many seconds. Network models can produce persistent and ramping activity, but the positive feedback that is critical for these slow dynamics can cause sensitivity to perturbations. Here we use electrophysiology and optogenetic perturbations in mouse premotor cortex to probe robustness of persistent neural representations during motor planning. Preparatory activity is remarkably robust to large-scale unilateral silencing: detailed neural dynamics that drive specific future movements were quickly and selectively restored by the network. Selectivity did not recover after bilateral silencing of premotor cortex. Perturbations to one hemisphere are thus corrected by information from the other hemisphere. Corpus callosum bisections demonstrated that premotor cortex hemispheres can maintain preparatory activity independently. Redundancy across selectively coupled modules, as we observed in premotor cortex, is a hallmark of robust control systems. Network models incorporating these principles show robustness that is consistent with data. PMID:27074502

  4. [Electrographic changes in isolated cat cortex under the influence of sleep neuropeptide].

    PubMed

    Bogoslovskiĭ, M M; Karmanova, I G; Maksimuk, V F; Al'bertin, S V

    1979-01-01

    Experiments on adult cats with isolated cerebral cortex show that suboccipital olygopeptide administration (10 and 15 mg/kg) induces electrographic manifestation of the slow wave sleep (SWS) in the isolated cortex. Slow synchronous waves reflecting the onset of SWS appear in the isolated cortex 0.2-1.5 sec earlier than in the control hemisphere. The same administration prevents the onset of paradoxical sleep (PS) up to 2 hours from the beginning of the experiment. In all experiments, manifestation of the PS was recorded in both hemispheres simultaneously.

  5. Modulation of proprioceptive integration in the motor cortex shapes human motor learning.

    PubMed

    Rosenkranz, Karin; Rothwell, John C

    2012-06-27

    Sensory and motor systems interact closely during movement performance. Furthermore, proprioceptive feedback from ongoing movements provides an important input for successful learning of a new motor skill. Here, we show in humans that attention to proprioceptive input during a purely sensory task can influence subsequent learning of a novel motor task. We applied low-amplitude vibration to the abductor pollicis brevis (APB) muscle of eight healthy volunteers for 15 min while they discriminated either a small change in vibration frequency or the presence of a simultaneous weak cutaneous stimulus. Before and after the sensory attention tasks, we evaluated the following in separate experiments: (1) sensorimotor interaction in the motor cortex by testing the efficacy of proprioceptive input to reduce GABA(A)ergic intracortical inhibition using paired-pulse transcranial magnetic stimulation, and (2) how well the same subjects learned a ballistic thumb abduction task using the APB muscle. Performance of the vibration discrimination task increased the interaction of proprioceptive input with motor cortex excitability in the APB muscle, whereas performance in the cutaneous discrimination task had the opposite effect. There was a significant correlation between the integration of proprioceptive input in the motor cortex and the motor learning gain: increasing the integration of proprioceptive input from the APB increased the rate of motor learning and reduced performance variability, while decreasing proprioceptive integration had opposite effects. These findings suggest that the sensory attention tasks transiently change how proprioceptive input is integrated into the motor cortex and that these sensory changes drive subsequent learning behavior in the human motor cortex.

  6. Motor Cortex Activity Organizes the Developing Rubrospinal System

    PubMed Central

    Williams, Preston T.J.A.

    2015-01-01

    The corticospinal and rubrospinal systems function in skilled movement control. A key question is how do these systems develop the capacity to coordinate their motor functions and, in turn, if the red nucleus/rubrospinal tract (RN/RST) compensates for developmental corticospinal injury? We used the cat to investigate whether the developing rubrospinal system is shaped by activity-dependent interactions with the developing corticospinal system. We unilaterally inactivated M1 by muscimol microinfusion between postnatal weeks 5 and 7 to examine activity-dependent interactions and whether the RN/RST compensates for corticospinal tract (CST) developmental motor impairments and CST misprojections after M1 inactivation. We examined the RN motor map and RST cervical projections at 7 weeks of age, while the corticospinal system was inactivated, and at 14 weeks, after activity returned. During M1 inactivation, the RN on the same side showed normal RST projections and reduced motor thresholds, suggestive of precocious development. By contrast, the RN on the untreated/active M1 side showed sparse RST projections and an immature motor map. After M1 activity returned later in adolescent cat development, RN on the active M1/CST side continued to show a substantial loss of spinal terminations and an impaired motor map. RN/RST on the inactivated side regressed to a smaller map and fewer axons. Our findings suggest that the developing rubrospinal system is under activity-dependent regulation by the corticospinal system for establishing mature RST connections and RN motor map. The lack of RS compensation on the non-inactivated side can be explained by development of ipsilateral misprojections from the active M1 that outcompete the RST. SIGNIFICANCE STATEMENT Skilled movements reflect the activity of multiple descending motor systems and their interactions with spinal motor circuits. Currently, there is little insight into whether motor systems interact during development to

  7. Theta-burst stimulation over primary motor cortex degrades early motor learning.

    PubMed

    Iezzi, Ennio; Suppa, Antonio; Conte, Antonella; Agostino, Rocco; Nardella, Andrea; Berardelli, Alfredo

    2010-02-01

    Theta-burst stimulation (TBS) is currently used for inducing long-lasting changes in primary motor cortex (M1) excitability. More information is needed on how M1 is involved in early motor learning (practice-related improvement in motor performance, motor retention and motor consolidation). We investigated whether inhibitory continuous TBS (cTBS) is an effective experimental approach for modulating early motor learning of a simple finger movement in healthy humans. In a short task, 11 subjects practised 160 movements, and in a longer task also testing motor consolidation ten subjects practised 600 movements. During both experiments subjects randomly received real or sham cTBS over the left M1. Motor evoked potentials were tested at baseline and 7 min after cTBS. In the 160-movement experiment to test motor retention, 20 movements were repeated 30 min after motor practice ended. In the 600-movement experiment motor retention was assessed 15 and 30 min after motor practice ended, motor consolidation was tested by performing 20 movements 24 h after motor practice ended. Kinematic variables - movement amplitude, peak velocity and peak acceleration - were measured. cTBS significantly reduced the practice-related improvement in motor performance of finger movements in the experiment involving 160 movements and in the first part of the experiment involving 600 movements. After cTBS, peak velocity and peak acceleration of the 20 movements testing motor retention decreased whereas those testing motor consolidation remained unchanged. cTBS over M1 degrades practice-related improvement in motor performance and motor retention, but not motor consolidation of a voluntary finger movement.

  8. A systematic review of non-motor rTMS induced motor cortex plasticity

    PubMed Central

    Nordmann, Grégory; Azorina, Valeriya; Langguth, Berthold; Schecklmann, Martin

    2015-01-01

    Motor cortex excitability can be measured by single- and paired-pulse transcranial magnetic stimulation (TMS). Repetitive transcranial magnetic stimulation (rTMS) can induce neuroplastic effects in stimulated and in functionally connected cortical regions. Due to its ability to non-invasively modulate cortical activity, rTMS has been investigated for the treatment of various neurological and psychiatric disorders. However, such studies revealed a high variability of both clinical and neuronal effects induced by rTMS. In order to better elucidate this meta-plasticity, rTMS-induced changes in motor cortex excitability have been monitored in various studies in a pre-post stimulation design. Here, we give a literature review of studies investigating motor cortex excitability changes as a neuronal marker for rTMS effects over non-motor cortical areas. A systematic literature review in April 2014 resulted in 29 articles in which motor cortex excitability was assessed before and after rTMS over non-motor areas. The majority of the studies focused on the stimulation of one of three separate cortical areas: the prefrontal area (17 studies), the cerebellum (8 studies), or the temporal cortex (3 studies). One study assessed the effects of multi-site rTMS. Most studies investigated healthy controls but some also stimulated patients with neuropsychiatric conditions (e.g., affective disorders, tinnitus). Methods and findings of the identified studies were highly variable showing no clear systematic pattern of interaction of non-motor rTMS with measures of motor cortex excitability. Based on the available literature, the measurement of motor cortex excitability changes before and after non-motor rTMS has only limited value in the investigation of rTMS related meta-plasticity as a neuronal state or as a trait marker for neuropsychiatric diseases. Our results do not suggest that there are systematic alterations of cortical excitability changes during rTMS treatment, which calls

  9. A systematic review of non-motor rTMS induced motor cortex plasticity.

    PubMed

    Nordmann, Grégory; Azorina, Valeriya; Langguth, Berthold; Schecklmann, Martin

    2015-01-01

    Motor cortex excitability can be measured by single- and paired-pulse transcranial magnetic stimulation (TMS). Repetitive transcranial magnetic stimulation (rTMS) can induce neuroplastic effects in stimulated and in functionally connected cortical regions. Due to its ability to non-invasively modulate cortical activity, rTMS has been investigated for the treatment of various neurological and psychiatric disorders. However, such studies revealed a high variability of both clinical and neuronal effects induced by rTMS. In order to better elucidate this meta-plasticity, rTMS-induced changes in motor cortex excitability have been monitored in various studies in a pre-post stimulation design. Here, we give a literature review of studies investigating motor cortex excitability changes as a neuronal marker for rTMS effects over non-motor cortical areas. A systematic literature review in April 2014 resulted in 29 articles in which motor cortex excitability was assessed before and after rTMS over non-motor areas. The majority of the studies focused on the stimulation of one of three separate cortical areas: the prefrontal area (17 studies), the cerebellum (8 studies), or the temporal cortex (3 studies). One study assessed the effects of multi-site rTMS. Most studies investigated healthy controls but some also stimulated patients with neuropsychiatric conditions (e.g., affective disorders, tinnitus). Methods and findings of the identified studies were highly variable showing no clear systematic pattern of interaction of non-motor rTMS with measures of motor cortex excitability. Based on the available literature, the measurement of motor cortex excitability changes before and after non-motor rTMS has only limited value in the investigation of rTMS related meta-plasticity as a neuronal state or as a trait marker for neuropsychiatric diseases. Our results do not suggest that there are systematic alterations of cortical excitability changes during rTMS treatment, which calls

  10. Inhibitory modulation of cat somatosensory cortex: a pharmacological study.

    PubMed

    Brailowsky, S; Knight, R T

    1984-11-26

    In anesthetized preparations, GABA and taurine produced rapid, reversible inhibition of the negative component (N20) of the primary somatosensory evoked potential (SEP) without effect on the earlier positivity (P11). This effect was also produced by low doses of 4-aminopyridine. Neither bicuculline or picrotoxin antagonized these drug effects. A predominance of type B GABA receptors in the superficial layers of the somatosensory cortex is proposed.

  11. Computing reaching dynamics in motor cortex with Cartesian spatial coordinates.

    PubMed

    Tanaka, Hirokazu; Sejnowski, Terrence J

    2013-02-01

    How neurons in the primary motor cortex control arm movements is not yet understood. Here we show that the equations of motion governing reaching simplify when expressed in spatial coordinates. In this fixed reference frame, joint torques are the sums of vector cross products between the spatial positions of limb segments and their spatial accelerations and velocities. The consequences that follow from this model explain many properties of neurons in the motor cortex, including directional broad, cosinelike tuning, nonuniformly distributed preferred directions dependent on the workspace, and the rotation of the population vector during arm movements. Remarkably, the torques can be directly computed as a linearly weighted sum of responses from cortical motoneurons, and the muscle tensions can be obtained as rectified linear sums of the joint torques. This allows the required muscle tensions to be computed rapidly from a trajectory in space with a feedforward network model.

  12. Shaping motor cortex plasticity through proprioception.

    PubMed

    Avanzino, Laura; Pelosin, Elisa; Abbruzzese, Giovanni; Bassolino, Michela; Pozzo, Thierry; Bove, Marco

    2014-10-01

    Short-term upper limb disuse induces a hemispheric unbalance between the primary motor cortices (M1s). However, it is still unclear whether these changes are mainly attributable to the absence of voluntary movements or to the reduction of proprioceptive information. The goal of this work was to investigate the role of proprioception in modulating hemispheric balance during a short-term right arm immobilization. We evaluated the 2 M1s excitability and the interhemispheric inhibition (IHI) between M1s in 3 groups of healthy subjects. Two groups received during the immobilization a proprioceptive (P-VIB, 80 Hz) and tactile (T-VIB, 30 Hz) vibration to the right hand, respectively. Another group did not receive any conditioning sensory inputs (No-VIB). We found that in the No-VIB and in the T-VIB groups immobilization induced a decrease of left M1 excitability and IHI from left to right hemisphere and an increase of right M1 excitability and IHI from right to left hemisphere. Differently, only a partial decrease in left M1 excitability, no change in right M1 excitability and in IHI was observed in the P-VIB group. Our findings demonstrate that the maintenance of dynamic proprioceptive inputs in an immobilized arm through muscle vibration can prevent the hemispheric unbalance induced by short-term limb disuse.

  13. The Organization of the Forelimb Representation of the C57BL/6 Mouse Motor Cortex as Defined by Intracortical Microstimulation and Cytoarchitecture

    PubMed Central

    Adkins, DeAnna L.; Donlan, Nicole A.; Asay, Aaron L.; Thomas, Nagheme; Kleim, Jeffrey A.

    2011-01-01

    The organization of forelimb representation areas of the monkey, cat, and rat motor cortices has been studied in depth, but its characterization in the mouse lags far behind. We used intracortical microstimulation (ICMS) and cytoarchitectonics to characterize the general organization of the C57BL/6 mouse motor cortex, and the forelimb representation in more detail. We found that the forelimb region spans a large area of frontal cortex, bordered primarily by vibrissa, neck, shoulder, and hindlimb representations. It included a large caudal forelimb area, dominated by digit representation, and a small rostral forelimb area, containing elbow and wrist representations. When the entire motor cortex was mapped, the forelimb was found to be the largest movement representation, followed by head and hindlimb representations. The ICMS-defined motor cortex spanned cytoarchitecturally identified lateral agranular cortex (AGl) and also extended into medial agranular cortex. Forelimb and hindlimb representations extended into granular cortex in a region that also had cytoarchitectural characteristics of AGl, consistent with the primary motor–somatosensory overlap zone (OL) characterized in rats. Thus, the mouse motor cortex has homologies with the rat in having 2 forelimb representations and an OL but is distinct in the predominance of digit representations. PMID:20739477

  14. Motor cortex stimulation enhances motor recovery and reduces peri-infarct dysfunction following ischemic insult.

    PubMed

    Kleim, Jeffrey A; Bruneau, Rochelle; VandenBerg, Penny; MacDonald, Erin; Mulrooney, Renee; Pocock, David

    2003-12-01

    Recovery of motor function following stroke is believed to be supported, at least in part, by functional compensation involving residual neural tissue. The present study used a rodent model of focal ischemia and intracortical microstimulation (ICMS) to examine the behavioral and physiological effects of cortical stimulation in combination with motor rehabilitation. Adult rats were trained to criterion on a single pellet reaching task before ICMS was used to derive maps of movement representations within forelimb motor cortex contralateral to the trained paw. All animals then received a focal ischemic infarct within the motor map. A cortical surface electrode was implanted over the motor cortex. Low levels of electrical stimulation were applied during rehabilitative training on the same reaching task for 10 days and ICMS used to derive a second motor map. Results showed that both monopolar and bipolar cortical stimulation significantly enhanced motor recovery and increased the area of cortex from which microstimulation movements could be evoked. The results demonstrate the behavioral and neurophysiological benefits of cortical stimulation in combination with rehabilitation for recovery from stroke.

  15. Normalization of cell responses in cat striate cortex

    NASA Technical Reports Server (NTRS)

    Heeger, D. J.

    1992-01-01

    Simple cells in the striate cortex have been depicted as half-wave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, a modified version of the linear/energy model is presented in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data.

  16. Cerebellum to motor cortex paired associative stimulation induces bidirectional STDP-like plasticity in human motor cortex.

    PubMed

    Lu, Ming-Kuei; Tsai, Chon-Haw; Ziemann, Ulf

    2012-01-01

    The cerebellum is crucially important for motor control and adaptation. Recent non-invasive brain stimulation studies have indicated the possibility to alter the excitability of the cerebellum and its projections to the contralateral motor cortex, with behavioral consequences on motor control and adaptation. Here we sought to induce bidirectional spike-timing dependent plasticity (STDP)-like modifications of motor cortex (M1) excitability by application of paired associative stimulation (PAS) in healthy subjects. Conditioning stimulation over the right lateral cerebellum (CB) preceded focal transcranial magnetic stimulation (TMS) of the left M1 hand area at an interstimulus interval of 2 ms (CB→M1 PAS(2 ms)), 6 ms (CB→M1 PAS(6 ms)) or 10 ms (CB→M1 PAS(10 ms)) or randomly alternating intervals of 2 and 10 ms (CB→M1 PAS(Control)). Effects of PAS on M1 excitability were assessed by the motor-evoked potential (MEP) amplitude, short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and cerebellar-motor cortex inhibition (CBI) in the first dorsal interosseous muscle of the right hand. CB→M1 PAS(2 ms) resulted in MEP potentiation, CB→M1 PAS(6 ms) and CB→M1 PAS(10 ms) in MEP depression, and CB→M1 PAS(Control) in no change. The MEP changes lasted for 30-60 min after PAS. SICI and CBI decreased non-specifically after all PAS protocols, while ICF remained unaltered. The physiological mechanisms underlying these MEP changes are carefully discussed. Findings support the notion of bidirectional STDP-like plasticity in M1 mediated by associative stimulation of the cerebello-dentato-thalamo-cortical pathway and M1. Future studies may investigate the behavioral significance of this plasticity.

  17. Functional Plasticity in Somatosensory Cortex Supports Motor Learning by Observing.

    PubMed

    McGregor, Heather R; Cashaback, Joshua G A; Gribble, Paul L

    2016-04-04

    An influential idea in neuroscience is that the sensory-motor system is activated when observing the actions of others [1, 2]. This idea has recently been extended to motor learning, in which observation results in sensory-motor plasticity and behavioral changes in both motor and somatosensory domains [3-9]. However, it is unclear how the brain maps visual information onto motor circuits for learning. Here we test the idea that the somatosensory system, and specifically primary somatosensory cortex (S1), plays a role in motor learning by observing. In experiment 1, we applied stimulation to the median nerve to occupy the somatosensory system with unrelated inputs while participants observed a tutor learning to reach in a force field. Stimulation disrupted motor learning by observing in a limb-specific manner. Stimulation delivered to the right arm (the same arm used by the tutor) disrupted learning, whereas left arm stimulation did not. This is consistent with the idea that a somatosensory representation of the observed effector must be available during observation for learning to occur. In experiment 2, we assessed S1 cortical processing before and after observation by measuring somatosensory evoked potentials (SEPs) associated with median nerve stimulation. SEP amplitudes increased only for participants who observed learning. Moreover, SEPs increased more for participants who exhibited greater motor learning following observation. Taken together, these findings support the idea that motor learning by observing relies on functional plasticity in S1. We propose that visual signals about the movements of others are mapped onto motor circuits for learning via the somatosensory system.

  18. Transspinal direct current stimulation immediately modifies motor cortex sensorimotor maps

    PubMed Central

    Song, Weiguo; Truong, Dennis Q.; Bikson, Marom

    2015-01-01

    Motor cortex (MCX) motor representation reorganization occurs after injury, learning, and different long-term stimulation paradigms. The neuromodulatory approach of transspinal direct current stimulation (tsDCS) has been used to promote evoked cortical motor responses. In the present study, we used cathodal tsDCS (c-tsDCS) of the rat cervical cord to determine if spinal cord activation can modify the MCX forelimb motor map. We used a finite-element method model based on coregistered high-resolution rat MRI and microcomputed tomography imaging data to predict spinal current density to target stimulation to the caudal cervical enlargement. We examined the effects of cathodal and anodal tsDCS on the H-reflex and c-tsDCS on responses evoked by intracortical microstimulation (ICMS). To determine if cervical c-tsDCS also modified MCX somatic sensory processing, we examined sensory evoked potentials (SEPs) produced by wrist electrical stimulation and induced changes in ongoing activity. Cervical c-tsDCS enhanced the H-reflex, and anodal depressed the H-reflex. Using cathodal stimulation to examine cortical effects, we found that cervical c-tsDCS immediately modified the forelimb MCX motor map, with decreased thresholds and an expanded area. c-tsDCS also increased SEP amplitude in the MCX. The magnitude of changes produced by c-tsDCS were greater on the motor than sensory response. Cervical c-tsDCS more strongly enhanced forelimb than hindlimb motor representation and had no effect on vibrissal representation. The finite-element model indicated current density localized to caudal cervical segments, informing forelimb motor selectivity. Our results suggest that c-tsDCS augments spinal excitability in a spatially selective manner and may improve voluntary motor function through MCX representational plasticity. PMID:25673738

  19. Simultaneous high-definition transcranial direct current stimulation of the motor cortex and motor imagery.

    PubMed

    Baxter, Bryan S; Edelman, Bradley; Zhang, Xiaotong; Roy, Abhrajeet; He, Bin

    2014-01-01

    Transcranial direct current stimulation (tDCS) has been used to affect the excitability of neurons within the cerebral cortex. Improvements in motor learning have been found in multiple studies when tDCS was applied to the motor cortex during or before task learning is performed. The application of tDCS to motor imagery, a cognitive task showing activation in similar areas to motor execution, has resulted in differing effects based on the amplitude and duration of stimulation. We utilize high definition tDCS, a more spatially localized version of tDCS, to investigate the effect of anodal stimulation on human motor imagery performance. In parallel, we model this stimulation using a finite element model to calculate stimulation area and electrical field amplitude within the brain in the motor cortex and non-stimulated frontal and parietal regions. Overall, we found a delayed increase in resting baseline power 30 minutes post stimulation in both the right and left sensorimotor cortices which resulted in an increase in event-related desynchronization.

  20. [Correlation of evoked potentials in the frontal cortex and hippocampus of cats in emotional stress].

    PubMed

    Vanetsian, G L; Pavlova, I V

    2002-01-01

    Averaged auditory evoked potentials (AEPs) were recorded in symmetric points of the frontal cortex and dorsal hippocampus of cats performing acquired conditioned food-procuring reaction reinforced in 100% cases, urgent transition to 30%-reinforcement, and return to 100%-reinforcement. Emotional stress estimated by a heart rate rise developed during increased food motivation of a cat as well as during change in ordinary food-procuring stereotype. The emotional stress was accompanied by a high positive correlation of cortical and hippocampal AEPs. Decrease in the stress level led to a drop between AEP correlations and appearance of their negative values. In emotional stress, the interactions between the frontal cortex and dorsal hippocampus were asymmetric: right-side correlations were higher.

  1. Epidural motor cortex stimulation suppresses somatosensory evoked potentials in the primary somatosensory cortex of the rat.

    PubMed

    Chiou, Ruei-Jen; Lee, Hsiao-Yun; Chang, Chen-Wei; Lin, Kuan-Hung; Kuo, Chung-Chih

    2012-06-29

    Motor cortex stimulation (MCS) is a promising clinical procedure to help alleviate chronic pain. Animal models demonstrated that MCS is effective in lessening nocifensive behaviors. The present study explored the effects of MCS on cortical somatosensory evoked potentials (SEPs) recorded at the primary somatosensory cortex (SI) of the rat. SEPs were evoked by electrical stimulation applied to the contralateral forepaws. Effects of different intensities, frequencies, and durations of MCS were tested. MCS at ≥2V suppressed SEPs of the ipsilateral SI. Suppression lasted 120 min at an intensity of 5 V. The optimal frequency was 50 Hz, and the duration was 30s. In contrast, MCS did not affect SEPs recorded on the contralateral SI. Cortical stimulation out of the motor cortex did not induce a decrease in the ipsilateral SEPs. We also investigated involvement of the endogenous opioid system in this inhibition of SEPs induced by MCS. The opioid antagonist, naloxone (0.5 mg/kg), was administered 30 min before MCS. Application of naloxone completely prevented the inhibitory effect of MCS on ipsilateral SEPs. These results demonstrate that MCS blocked the transmission of somatosensory information to the primary somatosensory cortex, and this interference was mediated by the endogenous opioid system. This inhibitory effect on sensory transmission induced by MCS may reflect its antinociceptive effect.

  2. Combined effect of motor imagery and peripheral nerve electrical stimulation on the motor cortex.

    PubMed

    Saito, Kei; Yamaguchi, Tomofumi; Yoshida, Naoshin; Tanabe, Shigeo; Kondo, Kunitsugu; Sugawara, Kenichi

    2013-06-01

    Although motor imagery enhances the excitability of the corticospinal tract, there are no peripheral afferent inputs during motor imagery. In contrast, peripheral nerve electrical stimulation (ES) can induce peripheral afferent inputs; thus, a combination of motor imagery and ES may enhance the excitability of the corticospinal tract compared with motor imagery alone. Moreover, the level of stimulation intensity may also be related to the modulation of the excitability of the corticospinal tract during motor imagery. Here, we evaluated whether a combination of motor imagery and peripheral nerve ES influences the excitability of the corticospinal tract and measured the effect of ES intensity on the excitability induced during motor imagery. The imagined task was a movement that involved touching the thumb to the little finger, whereas ES involved simultaneous stimulation of the ulnar and median nerves at the wrist. Two different ES intensities were used, one above the motor threshold and another above the sensory threshold. Further, we evaluated whether actual movement with afferent input induced by ES modulates the excitability of the corticospinal tract as well as motor imagery. We found that a combination of motor imagery and ES enhanced the excitability of the motor cortex in the thenar muscle compared with the other condition. Furthermore, we established that the modulation of the corticospinal tract was related to ES intensity. However, we found that the excitability of the corticospinal tract induced by actual movement was enhanced by peripheral nerve ES above the sensory threshold.

  3. Columnar architecture sculpted by GABA circuits in developing cat visual cortex.

    PubMed

    Hensch, Takao K; Stryker, Michael P

    2004-03-12

    The mammalian visual cortex is organized into columns. Here, we examine cortical influences upon developing visual afferents in the cat by altering intrinsic gamma-aminobutyric acid (GABA)-mediated inhibition with benzodiazepines. Local enhancement by agonist (diazepam) infusion did not perturb visual responsiveness, but did widen column spacing. An inverse agonist (DMCM) produced the opposite effect. Thus, intracortical inhibitory circuits shape the geometry of incoming thalamic arbors, suggesting that cortical columnar architecture depends on neuronal activity.

  4. Motor cortex electrical stimulation augments sprouting of the corticospinal tract and promotes recovery of motor function.

    PubMed

    Carmel, Jason B; Martin, John H

    2014-01-01

    The corticospinal system-with its direct spinal pathway, the corticospinal tract (CST) - is the primary system for controlling voluntary movement. Our approach to CST repair after injury in mature animals was informed by our finding that activity drives establishment of connections with spinal cord circuits during postnatal development. After incomplete injury in maturity, spared CST circuits sprout, and partially restore lost function. Our approach harnesses activity to augment this injury-dependent CST sprouting and to promote function. Lesion of the medullary pyramid unilaterally eliminates all CST axons from one hemisphere and allows examination of CST sprouting from the unaffected hemisphere. We discovered that 10 days of electrical stimulation of either the spared CST or motor cortex induces CST axon sprouting that partially reconstructs the lost CST. Stimulation also leads to sprouting of the cortical projection to the magnocellular red nucleus, where the rubrospinal tract originates. Coordinated outgrowth of the CST and cortical projections to the red nucleus could support partial re-establishment of motor systems connections to the denervated spinal motor circuits. Stimulation restores skilled motor function in our animal model. Lesioned animals have a persistent forelimb deficit contralateral to pyramidotomy in the horizontal ladder task. Rats that received motor cortex stimulation either after acute or chronic injury showed a significant functional improvement that brought error rate to pre-lesion control levels. Reversible inactivation of the stimulated motor cortex reinstated the impairment demonstrating the importance of the stimulated system to recovery. Motor cortex electrical stimulation is an effective approach to promote spouting of spared CST axons. By optimizing activity-dependent sprouting in animals, we could have an approach that can be translated to the human for evaluation with minimal delay.

  5. High-Field Functional Imaging of Pitch Processing in Auditory Cortex of the Cat

    PubMed Central

    Butler, Blake E.; Hall, Amee J.; Lomber, Stephen G.

    2015-01-01

    The perception of pitch is a widely studied and hotly debated topic in human hearing. Many of these studies combine functional imaging techniques with stimuli designed to disambiguate the percept of pitch from frequency information present in the stimulus. While useful in identifying potential “pitch centres” in cortex, the existence of truly pitch-responsive neurons requires single neuron-level measures that can only be undertaken in animal models. While a number of animals have been shown to be sensitive to pitch, few studies have addressed the location of cortical generators of pitch percepts in non-human models. The current study uses high-field functional magnetic resonance imaging (fMRI) of the feline brain in an attempt to identify regions of cortex that show increased activity in response to pitch-evoking stimuli. Cats were presented with iterated rippled noise (IRN) stimuli, narrowband noise stimuli with the same spectral profile but no perceivable pitch, and a processed IRN stimulus in which phase components were randomized to preserve slowly changing modulations in the absence of pitch (IRNo). Pitch-related activity was not observed to occur in either primary auditory cortex (A1) or the anterior auditory field (AAF) which comprise the core auditory cortex in cats. Rather, cortical areas surrounding the posterior ectosylvian sulcus responded preferentially to the IRN stimulus when compared to narrowband noise, with group analyses revealing bilateral activity centred in the posterior auditory field (PAF). This study demonstrates that fMRI is useful for identifying pitch-related processing in cat cortex, and identifies cortical areas that warrant further investigation. Moreover, we have taken the first steps in identifying a useful animal model for the study of pitch perception. PMID:26225563

  6. Postnatal development of corticocortical efferents from area 17 in the cat's visual cortex

    SciTech Connect

    Price, D.J.; Zumbroich, T.J.

    1989-02-01

    We are interested in the postnatal development of corticocortical connections in the cat's visual cortex. In this study, we injected the anterograde tracer 3H-proline into visual cortical area 17 of kittens, aged 4-70 d, and adult cats to visualize the distribution of terminals of the association projections to areas 18, 19, 21a, and the lateral suprasylvian visual cortex. The density of anterograde label was quantified using computerized image analysis. There was dense labeling at topographically appropriate locations in area 18 in animals of all ages. In 4- and 8-d-old kittens, other extrastriate areas (19, 21a and the lateral suprasylvian cortex) contained only sparse label, localized in a few solitary axons; these areas were densely labeled in animals aged 12 d or more. In kittens aged 4-20 d there was considerable, widespread label within fibers located in the white matter, and many of these axons lay underneath regions of extrastriate, and also striate, cortex that were almost certainly not destined to be persistently innervated by cells at the injection site. This pattern of extensive white matter label was not seen in animals older than 20 d. In each extrastriate region, from the earliest age at which we identified dense cortical innervation from area 17, the terminals were distributed in clusters. At first these patches were mainly in infragranular layers, but later, during the second and third postnatal weeks, they began to appear in more superficial laminae. By 70 d, an adult-like distribution of terminals was found in each extrastriate area: most fibers appeared to end in layers II and III in areas 18, 19, and 21a and centered on layer IV in the medial bank of the middle suprasylvian sulcus in adult cats. We suggest that the development of ipsilateral association projections from area 17 to extrastriate cortex is a 2-stage process.

  7. Modulation of the motor cortex during singing-voice perception.

    PubMed

    Lévêque, Yohana; Schön, Daniele

    2015-04-01

    Several studies on action observation have shown that the biological dimension of movement modulates sensorimotor interactions in perception. In the present fMRI study, we tested the hypothesis that the biological dimension of sound modulates the involvement of the motor system in human auditory perception, using musical tasks. We first localized the vocal motor cortex in each participant. Then we compared the BOLD response to vocal, semi-vocal and non-vocal melody perception, and found greater activity for voice perception in the right sensorimotor cortex. We additionally ran a psychophysiological interaction analysis with the right sensorimotor as a seed, showing that the vocal dimension of the stimuli enhanced the connectivity between the seed region and other important nodes of the auditory dorsal stream. Finally, the participants' vocal ability was negatively correlated to the voice effect in the Inferior Parietal Lobule. These results suggest that the biological dimension of singing-voice impacts the activity within the auditory dorsal stream, probably via a facilitated matching between the perceived sound and the participant motor representations.

  8. High-intensity Interval Exercise Promotes Motor Cortex Disinhibition and Early Motor Skill Consolidation.

    PubMed

    Stavrinos, Ellen L; Coxon, James P

    2017-04-01

    Gamma-aminobutyric acid (GABA) inhibition shapes motor cortex output, gates synaptic plasticity in the form of long-term potentiation, and plays an important role in motor learning. Remarkably, recent studies have shown that acute cardiovascular exercise can improve motor memory, but the cortical mechanisms are not completely understood. We investigated whether an acute bout of lower-limb high-intensity interval (HIT) exercise could promote motor memory formation in humans through changes in cortical inhibition within the hand region of the primary motor cortex. We used TMS to assess the input-output relationship, along with inhibition involving GABAA and GABAB receptors. Measures were obtained before and after a 20-min session of HIT cycling (exercise group) or rest (control group). We then had the same participants learn a new visuomotor skill and perform a retention test 5 hr later in the absence of sleep. No differences were found in corticomotor excitability or GABAB inhibition; however, synaptic GABAA inhibition was significantly reduced for the exercise group but not the control group. HIT exercise was found to enhance motor skill consolidation. These findings link modification of GABA to improved motor memory consolidation after HIT exercise and suggest that the beneficial effects of exercise on consolidation might not be dependent on sleep.

  9. [The effect of noradrenaline on the neuronal reactions of the motor cortex evoked by conditional stimulation].

    PubMed

    Storozhuk, V M; Stezhka, V V; Ivanova, S F

    1990-01-01

    In chronic experiments on cats the influence of iontophoretic application of adrenomimetic ephedrin and beta-adrenoblocker obsidan (propranolol) on motor cortex neuron reactions following conditional stimuli was investigated under instrumental placing reaction. It was shown for a majority of neurons that the background impulse activity and reactions following conditional stimulation were suppressed by the influence of ephedrin and on the contrary were increased by obsidan application. It is concluded that there exists a consistent tonic suppressing influence of the noradrenergic system on background and evoked cortical neurons impulse activity in the natural state. It is supposed that noradrenergic influence temporal increase may serve as an important link in mechanisms of external inhibition during stress situations, aversive effects, and distractive external excitations.

  10. Therapy induces widespread reorganization of motor cortex after complete spinal transection that supports motor recovery.

    PubMed

    Ganzer, Patrick D; Manohar, Anitha; Shumsky, Jed S; Moxon, Karen A

    2016-05-01

    Reorganization of the somatosensory system and its relationship to functional recovery after spinal cord injury (SCI) has been well studied. However, little is known about the impact of SCI on organization of the motor system. Recent studies suggest that step-training paradigms in combination with spinal stimulation, either electrically or through pharmacology, are more effective than step training alone at inducing recovery and that reorganization of descending corticospinal circuits is necessary. However, simpler, passive exercise combined with pharmacotherapy has also shown functional improvement after SCI and reorganization of, at least, the sensory cortex. In this study we assessed the effect of passive exercise and serotonergic (5-HT) pharmacological therapies on behavioral recovery and organization of the motor cortex. We compared the effects of passive hindlimb bike exercise to bike exercise combined with daily injections of 5-HT agonists in a rat model of complete mid-thoracic transection. 5-HT pharmacotherapy combined with bike exercise allowed the animals to achieve unassisted weight support in the open field. This combination of therapies also produced extensive expansion of the axial trunk motor cortex into the deafferented hindlimb motor cortex and, surprisingly, reorganization within the caudal and even the rostral forelimb motor cortex areas. The extent of the axial trunk expansion was correlated to improvement in behavioral recovery of hindlimbs during open field locomotion, including weight support. From a translational perspective, these data suggest a rationale for developing and optimizing cost-effective, non-invasive, pharmacological and passive exercise regimes to promote plasticity that supports restoration of movement after spinal cord injury.

  11. [Connections of field 17 of the visual cortex with the mammillary nuclei in cats].

    PubMed

    Sergeeva, I G

    1977-11-01

    Using optical techniques by Nauta--Gygax, Wiitanen and Eager, degenerating nerve fibres and terminals were demonstrated to be present in the hypothalamic mammillary nuclei 9 days after a part of field 17 of the brain cortex was extirpated. Electron microscopic examination revealed different changes in large and small terminals of the boutons 5, 7 and 11 days after similar operations. The data represented demonstrate direct monosynaptic bilateral connections in field 17 of the optic cortex with the hypothalamic mammillary nuclei in cats. They are realized by fine fibrillae terminating mainly in large terminal boutons which form synapses on big and small dendritic branches. Thus, there is a structural base for the immediate influence of the optic cortex on the posterior hypothalamus.

  12. Dorsal anterior cingulate cortex modulates supplementary motor area in coordinated unimanual motor behavior

    PubMed Central

    Asemi, Avisa; Ramaseshan, Karthik; Burgess, Ashley; Diwadkar, Vaibhav A.; Bressler, Steven L.

    2015-01-01

    Motor control is integral to all types of human behavior, and the dorsal Anterior Cingulate Cortex (dACC) is thought to play an important role in the brain network underlying motor control. Yet the role of the dACC in motor control is under-characterized. Here we aimed to characterize the dACC’s role in adolescent brain network interactions during a simple motor control task involving visually coordinated unimanual finger movements. Network interactions were assessed using both undirected and directed functional connectivity analysis of functional Magnetic Resonance Imaging (fMRI) Blood-Oxygen-Level-Dependent (BOLD) signals, comparing the task with a rest condition. The relation between the dACC and Supplementary Motor Area (SMA) was compared to that between the dACC and Primary Motor Cortex (M1). The directed signal from dACC to SMA was significantly elevated during motor control in the task. By contrast, the directed signal from SMA to dACC, both directed signals between dACC and M1, and the undirected functional connections of dACC with SMA and M1, all did not differ between task and rest. Undirected coupling of dACC with both SMA and dACC, and only the dACC-to-SMA directed signal, were significantly greater for a proactive than a reactive task condition, suggesting that dACC plays a role in motor control by maintaining stimulus timing expectancy. Overall, these results suggest that the dACC selectively modulates the SMA during visually coordinated unimanual behavior in adolescence. The role of the dACC as an important brain area for the mediation of task-related motor control may be in place in adolescence, continuing into adulthood. The task and analytic approach described here should be extended to the study of healthy adults to examine network profiles of the dACC during basic motor behavior. PMID:26089783

  13. Electrical stimulation of the motor cortex: theoretical considerations.

    PubMed

    Grandori, F; Rossini, P

    1988-01-01

    The aim of this paper is to present the results of a theoretical analysis of the intracranial fields produced by electrical stimulation of the unexposed motor cortex with surface electrodes in humans. Simulations of a first approximation model of the head indicate that the intensity and the spatial configuration of the intracranial fields can be controlled, to a great extent, by proper choice of the location and of the number of the stimulating electrodes. Fields are shown to be reasonably insensitive to changes of some crucial parameters, like the number of the stimulating electrodes and the ratio between the conductivity of the skull and that of the other tissues.

  14. Reorganization between preparatory and movement population responses in motor cortex

    PubMed Central

    Elsayed, Gamaleldin F.; Lara, Antonio H.; Kaufman, Matthew T.; Churchland, Mark M.; Cunningham, John P.

    2016-01-01

    Neural populations can change the computation they perform on very short timescales. Although such flexibility is common, the underlying computational strategies at the population level remain unknown. To address this gap, we examined population responses in motor cortex during reach preparation and movement. We found that there exist exclusive and orthogonal population-level subspaces dedicated to preparatory and movement computations. This orthogonality yielded a reorganization in response correlations: the set of neurons with shared response properties changed completely between preparation and movement. Thus, the same neural population acts, at different times, as two separate circuits with very different properties. This finding is not predicted by existing motor cortical models, which predict overlapping preparation-related and movement-related subspaces. Despite orthogonality, responses in the preparatory subspace were lawfully related to subsequent responses in the movement subspace. These results reveal a population-level strategy for performing separate but linked computations. PMID:27807345

  15. The effect of deception on motor cortex excitability.

    PubMed

    Kelly, Karen J; Murray, Elizabeth; Barrios, Veronica; Gorman, Jamie; Ganis, Giorgio; Keenan, Julian Paul

    2009-01-01

    Although a number of recent neuroimaging studies have examined the relationship between the brain and deception, the neurological correlates of deception are still not well understood. The present study sought to assess differences in cortical excitability during the act of deception by measuring motor evoked potentials (MEPs) during transcranial magnetic stimulation (TMS). Sports fanatics and low-affiliation sports fans were presented with preferred and rival team images and were asked to deceptively or honestly identify their favored team. Hemispheric differences were found including greater excitability of the left motor cortex during the generation of deceptive responses. In contrast to current physiological measures of deception, level of arousal was not found to differentiate truthful and deceptive responses. The results are presented in terms of a complex cognitive pattern contributing to the generation of deceptive responses.

  16. Hemispheric asymmetry of ipsilateral motor cortex activation in motor skill learning.

    PubMed

    Suzuki, Tomotaka; Higashi, Toshio; Takagi, Mineko; Sugawara, Kenichi

    2013-09-11

    In this study, we investigated how ipsilateral motor cortex (M1) activation during unimanual hand movements and hemispheric asymmetry changed after motor skill learning. Eleven right-handed participants preformed a two-ball-rotation motor task with the right and the left hand, separately, in all experimental sessions. Before and after exercise sessions, the degree of ipsilateral M1 activation during brief execution of the motor task was measured as changes in the size of motor-evoked potentials (MEPs) of the thenar and the first dorsal interosseous muscle of the nontask hand using transcranial magnetic stimulation. Before exercise, MEPs of the nontask hand were significantly facilitated on both sides during the motor task. After exercise, facilitation of MEPs of the nontask hand during the motor task was significantly reduced for the right hand (thenar: P=0.014, first dorsal interosseous: P=0.022) but not for the left hand. We conclude that ipsilateral M1 activation, associated with a complex motor task, is first symmetrical in both hemispheres. However, on exercise, ipsilateral activation is reduced only in left M1, indicating a stronger learning-dependent modification of motor networks within the left hemisphere.

  17. Counterfactual thinking affects the excitability of the motor cortex.

    PubMed

    Vicario, Carmelo M; Rafal, Robert D; Avenanti, Alessio

    2015-04-01

    Evidence suggests that monetary reward and affective experiences induce activity in the cortical motor system. Nevertheless, it is unclear whether counterfactual thinking related to wrong choices that lead to monetary loss and regret affects motor excitability. Using transcranial magnetic stimulation (TMS) of the motor cortex, we measured corticospinal excitability of 2 groups of healthy humans asked to actively guess the winning key among two possible alternatives (choice group); or passively assist to monetary outcomes randomly selected by the computer program (follow group). Results document a selective increment of the corticospinal excitability when a monetary loss outcome followed the key selection (i.e., in the choice group). On the other hand, no change in corticospinal excitability was found when participants passively assisted to a monetary loss randomly selected by the computer program (i.e., follow group). These findings suggest that counterfactual thinking and the negative emotional experiences arising from choices causing monetary loss--i.e., "I would have won instead of lost money if I'd made a different choice"--are mapped in the motor system.

  18. Behavioral cartography of visual functions in cat parietal cortex: areal and laminar dissociations.

    PubMed

    Lomber, S G

    2001-01-01

    The purpose of this review is to: (1) compare and contrast the relative contributions that the four principle regions in cat extrastriate parietal cortex make to a battery of visual tasks which require motion, spatial, or attentional processing; and (2) examine the laminar parcellation of visual behaviors within one of these parietal regions which mediates multiple visual behaviors. We examined a battery of visual tasks presumed to be mediated by parietal cortex, including direction of motion, differential motion, and landmark discriminations, and visual orienting to moving stimuli. As a control, we also examined performance on form (pattern and object) recognition tasks mediated by the temporal processing stream. The four regions of parietal cortex we examined included the: middle suprasylvian (MS) gyrus (area 7), anterior middle suprasylvian (aMS) sulcus (AMLS, ALLS), posterior middle suprasylvian (pMS) sulcus (PMLS, PLLS), and the dorsal posterior suprasylvian (dPS) gyrus (area 21a). The contributions made to each of the six different behavioral tasks was examined before, during, and after reversible cooling deactivation of each cortical area. Deactivation of pMS sulcal cortex resulted in deficits on all four tasks that required motion, spatial or attentional processing. Deactivation of aMS sulcal cortex resulted in deficits on only tasks that required motion processing. Deactivation of neither aMS nor pMS sulcal cortex yielded any deficits on the form recognition tasks. In contrast, deactivation of dPS cortex only produced deficits on the form recognition tasks. This finding confirmed our early hypothesis that dPS cortex is a key component of the temporal, and not the parietal, processing stream. Regardless of the task, no deficits were identified on any of the six tasks during deactivation of the MS gyrus. We then more closely examined pMS sulcal cortex to determine if its multiple functions could be dissociated on a laminar level. We found that cooling

  19. Augmenting Plasticity Induction in Human Motor Cortex by Disinhibition Stimulation.

    PubMed

    Cash, Robin F H; Murakami, Takenobu; Chen, Robert; Thickbroom, Gary W; Ziemann, Ulf

    2016-01-01

    Cellular studies showed that disinhibition, evoked pharmacologically or by a suitably timed priming stimulus, can augment long-term plasticity (LTP) induction. We demonstrated previously that transcranial magnetic stimulation evokes a period of presumably GABA(B)ergic late cortical disinhibition (LCD) in human primary motor cortex (M1). Here, we hypothesized that, in keeping with cellular studies, LCD can augment LTP-like plasticity in humans. In Experiment 1, patterned repetitive TMS was applied to left M1, consisting of 6 trains (intertrain interval, 8 s) of 4 doublets (interpulse interval equal to individual peak I-wave facilitation, 1.3-1.5 ms) spaced by the individual peak LCD (interdoublet interval (IDI), 200-250 ms). This intervention (total of 48 pulses applied over ∼45 s) increased motor-evoked potential amplitude, a marker of corticospinal excitability, in a right hand muscle by 147% ± 4%. Control experiments showed that IDIs shorter or longer than LCD did not result in LTP-like plasticity. Experiment 2 indicated topographic specificity to the M1 hand region stimulated by TMS and duration of the LTP-like plasticity of 60 min. In conclusion, GABA(B)ergic LCD offers a powerful new approach for augmenting LTP-like plasticity induction in human cortex. We refer to this protocol as disinhibition stimulation (DIS).

  20. Psychogenic paralysis and recovery after motor cortex transcranial magnetic stimulation.

    PubMed

    Chastan, Nathalie; Parain, Dominique

    2010-07-30

    Psychogenic paralysis presents a real treatment challenge. Despite psychotherapy, physiotherapy, antidepressants, acupuncture, or hypnosis, the outcome is not always satisfactory with persistent symptoms after long-term follow-up. We conducted a retrospective study to assess clinical features and to propose an alternative treatment based on repetitive transcranial magnetic stimulation (rTMS). Seventy patients (44 F/26 M, mean age: 24.7 +/- 16.6 years) experienced paraparesis (57%), monoparesis (37%), tetraparesis (3%), or hemiparesis (3%). A precipitating event was observed in 42 patients, primarily as a psychosocial event or a physical injury. An average of 30 stimuli over the motor cortex contralateral to the corresponding paralysis was delivered at low frequency with a circular coil. The rTMS was effective in 89% of cases, with a significantly better outcome for acute rather than chronic symptoms. In conclusion, motor cortex rTMS seem to be very effective in patients with psychogenic paralysis and could be considered a useful therapeutic option.

  1. Associative plasticity in intracortical inhibitory circuits in human motor cortex

    PubMed Central

    Russmann, Heike; Lamy, Jean-Charles; Shamim, Ejaz; Meunier, Sabine; Hallett, Mark

    2009-01-01

    Objective Paired-associative stimulation (PAS) is a transcranial magnetic stimulation technique inducing Hebbian-like synaptic plasticity in the human motor cortex (M1). PAS is produced by repetitive pairing of a peripheral nerve shock and a transcranial magnetic stimulus (TMS). Its effect is assessed by a change in size of a motor evoked response (MEP). MEP size results from excitatory and inhibitory influences exerted on cortical pyramidal cells, but no robust effects on inhibitory networks have been demonstrated so far. Method In 38 healthy volunteers, we assessed whether a PAS intervention influences three intracortical inhibitory circuits: short (SICI) and long (LICI) intracortical inhibitions reflecting activity of GABAA and GABAB interneurons respectively, and long afferent inhibition (LAI) reflecting activity of somatosensory inputs. Results After PAS, MEP sizes, LICI and LAI levels were significantly changed while changes of SICI were inconsistent. The changes in LICI and LAI lasted 45 minutes after PAS. Their direction depended on the delay between the arrival time of the afferent volley at the cortex and the TMS-induced cortical activation during the PAS. Conclusions PAS influences inhibitory circuits in M1. Significance PAS paradigms can demonstrate Hebbian-like plasticity at selected inhibitory networks as well as excitatory networks. PMID:19435676

  2. Reduced Motor Cortex Activity during Movement Preparation following a Period of Motor Skill Practice

    PubMed Central

    Wright, David J.; Holmes, Paul; Di Russo, Francesco; Loporto, Michela; Smith, Dave

    2012-01-01

    Experts in a skill produce movement-related cortical potentials (MRCPs) of smaller amplitude and later onset than novices. This may indicate that, following long-term training, experts require less effort to plan motor skill performance. However, no longitudinal evidence exists to support this claim. To address this, EEG was used to study the effect of motor skill training on cortical activity related to motor planning. Ten non-musicians took part in a 5-week training study learning to play guitar. At week 1, the MRCP was recorded from motor areas whilst participants played the G Major scale. Following a period of practice of the scale, the MRCP was recorded again at week 5. Results showed that the amplitude of the later pre-movement components were smaller at week 5 compared to week 1. This may indicate that, following training, less activity at motor cortex sites is involved in motor skill preparation. This supports claims for a more efficient motor preparation following motor skill training. PMID:23251647

  3. Different motor learning effects on excitability changes of motor cortex in muscle contraction state.

    PubMed

    Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Higashi, Toshio

    2013-09-01

    We aimed to investigate whether motor learning induces different excitability changes in the human motor cortex (M1) between two different muscle contraction states (before voluntary contraction [static] or during voluntary contraction [dynamic]). For the same, using motor evoked potentials (MEPs) obtained by transcranial magnetic stimulation (TMS), we compared excitability changes during these two states after pinch-grip motor skill learning. The participants performed a force output tracking task by pinch grip on a computer screen. TMS was applied prior to the pinch grip (static) and after initiation of voluntary contraction (dynamic). MEPs of the following muscles were recorded: first dorsal interosseous (FDI), thenar muscle (Thenar), flexor carpi radialis (FCR), and extensor carpi radialis (ECR) muscles. During both the states, motor skill training led to significant improvement of motor performance. During the static state, MEPs of the FDI muscle were significantly facilitated after motor learning; however, during the dynamic state, MEPs of the FDI, Thenar, and FCR muscles were significantly decreased. Based on the results of this study, we concluded that excitability changes in the human M1 are differentially influenced during different voluntary contraction states (static and dynamic) after motor learning.

  4. Functional Imaging of Auditory Cortex in Adult Cats using High-field fMRI

    PubMed Central

    Brown, Trecia A.; Gati, Joseph S.; Hughes, Sarah M.; Nixon, Pam L.; Menon, Ravi S.; Lomber, Stephen G.

    2014-01-01

    Current knowledge of sensory processing in the mammalian auditory system is mainly derived from electrophysiological studies in a variety of animal models, including monkeys, ferrets, bats, rodents, and cats. In order to draw suitable parallels between human and animal models of auditory function, it is important to establish a bridge between human functional imaging studies and animal electrophysiological studies. Functional magnetic resonance imaging (fMRI) is an established, minimally invasive method of measuring broad patterns of hemodynamic activity across different regions of the cerebral cortex. This technique is widely used to probe sensory function in the human brain, is a useful tool in linking studies of auditory processing in both humans and animals and has been successfully used to investigate auditory function in monkeys and rodents. The following protocol describes an experimental procedure for investigating auditory function in anesthetized adult cats by measuring stimulus-evoked hemodynamic changes in auditory cortex using fMRI. This method facilitates comparison of the hemodynamic responses across different models of auditory function thus leading to a better understanding of species-independent features of the mammalian auditory cortex. PMID:24637937

  5. Peripheral Nerve Injury in Developing Rats Reorganizes Representation Pattern in Motor Cortex

    NASA Astrophysics Data System (ADS)

    Donoghue, John P.; Sanes, Jerome N.

    1987-02-01

    We investigated the effect of neonatal nerve lesions on cerebral motor cortex organization by comparing the cortical motor representation of normal adult rats with adult rats that had one forelimb removed on the day of birth. Mapping of cerebral neocortex with electrical stimulation revealed an altered relationship between the motor cortex and the remaining muscles. Whereas distal forelimb movements are normally elicited at the lowest threshold in the motor cortex forelimb area, the same stimuli activated shoulder and trunk muscles in experimental animals. In addition, an expanded cortical representation of intact body parts was present and there was an absence of a distinct portion of motor cortex. These data demonstrate that representation patterns in motor cortex can be altered by peripheral nerve injury during development.

  6. Selective Long-term Reorganization of the Corticospinal Projection from the Supplementary Motor Cortex following Recovery from Lateral Motor Cortex Injury

    PubMed Central

    McNeal, David W.; Darling, Warren G.; Ge, Jizhi; Stilwell-Morecraft, Kimberly S.; Solon, Kathryn M.; Hynes, Stephanie M.; Pizzimenti, Marc A.; Rotella, Diane; Vanadurongvan, Tyler; Morecraft, Robert J.

    2013-01-01

    Brain injury affecting the frontal motor cortex or its descending axons often causes contralateral upper extremity paresis. Although recovery is variable, the underlying mechanisms supporting favorable motor recovery remain unclear. Since the medial wall of the cerebral hemisphere is often spared following brain injury and recent functional neuroimaging studies in patients indicate a potential role for this brain region in the recovery process, we investigated the long-term effects of isolated lateral frontal motor cortical injury on the corticospinal projection (CSP) from intact, ipsilesional supplementary motor cortex (M2). Following injury to the arm region of the primary motor (M1) and lateral premotor (LPMC) cortices, upper extremity recovery is accompanied by terminal axon plasticity in the contralateral CSP but not the ipsilateral CSP from M2. Furthermore, significant contralateral plasticity occurs only in lamina VII and dorsally within lamina IX. Thus, selective intraspinal sprouting transpires in regions containing interneurons, flexor-related motor neurons and motor neurons supplying intrinsic hand muscles which all play important roles in mediating reaching and digit movements. Following recovery, subsequent injury of M2 leads to reemergence of hand motor deficits. Considering the importance of the CSP in humans and the common occurrence of lateral frontal cortex injury, these findings suggest that spared supplementary motor cortex may serve as an important therapeutic target that should be considered when designing acute and long-term post-injury patient intervention strategies aimed to enhance the motor recovery process following lateral cortical trauma. PMID:20034062

  7. [The neuronal level of motor activity: determination of motor cortex excitability by TMS].

    PubMed

    Eichhammer, Peter; Langguth, Berthold; Müller, Jürgen; Hajak, Göran

    2005-04-01

    Transcranial magnetic stimulation as mapping method offers the possibility to measure aspects of motor cortex excitability painlessly and non-invasively. Using this neurophysiological tool, new insights into the effects of central-acting drugs are possible. Particularly striking seems to be the potential of this approach to gain new insights into neurobiological processes associated with neuropsychiatric diseases like schizophrenia or major depression. In combination with genetic aspects, TMS is able to bridge the gap between molecular research and clinical approach.

  8. Functional imaging of cat primary visual cortex with optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Rajagopalan, Uma M.; Takaoka, Hideyuki; Homma, Ryota; Kadono, Hirofumi; Tanifuji, Manabu

    2002-06-01

    We report the application of Optical coherence tomography (OCT) for visualizing a one dimensional depth resolved functional structure of cat brain in vivo. The OCT system is based on the known fact that neural activation induces structural changes such as capillary dilation and cellular swelling. Detecting these changes as an amplitude change of the scattered light, an OCT signal reflecting neural activity i.e., fOCT (functional OCT) could be obtained. Experiments have been done to obtain a depth resolved stimulus-specific profile of activation in cat visual cortex. Our results in one dimension indicate that indeed an orientation dependent functional signal could be obtained. Further, we show that this depth resolved fOCT signal is well correlated with the stimulus dependent column determined by OISI. Based on the results, the smallest functional unit in depth, resolved by the proposed system is around 40 micrometers . We are extending our system to perform two dimensional functional imaging.

  9. Magnetic stimulation of the human motor cortex evokes skin sympathetic nerve activity.

    PubMed

    Silber, D H; Sinoway, L I; Leuenberger, U A; Amassian, V E

    2000-01-01

    Single-pulse magnetic coil stimulation (Cadwell MES 10) over the cranium induces without pain an electric pulse in the underlying cerebral cortex. Stimulation over the motor cortex can elicit a muscle twitch. In 10 subjects, we tested whether motor cortical stimulation could also elicit skin sympathetic nerve activity (SSNA; n = 8) and muscle sympathetic nerve activity (MSNA; n = 5) in the peroneal nerve. Focal motor cortical stimulation predictably elicited bursts of SSNA but not MSNA; with successive stimuli, the SSNA responses did not readily extinguish (94% of discharges to the motor cortex evoked SSNA responses) and had predictable latencies [739 +/- 33 (SE) to 895 +/- 13 ms]. The SSNA responses were similar after stimulation of dominant and nondominant sides. Focal stimulation posterior to the motor cortex elicited extinguishable SSNA responses. In three of six subjects, anterior cortical stimulation evoked SSNA responses similar to those seen with motor cortex stimulation but without detectable movement; in the other subjects, anterior stimulation evoked less SSNA discharge than that seen with motor cortex stimulation. Contrasting with motor cortical stimulation, evoked SSNA responses were more readily extinguished with 1) peripheral stimulation that directly elicited forearm muscle activation accompanied by electromyograms similar to those with motor cortical stimulation; 2) auditory stimulation by the click of the energized coil when off the head; and 3) in preliminary experiments, finger afferent stimulation sufficient to cause tingling. Our findings are consistent with the hypothesis that motor cortex stimulation can cause activation of both alpha-motoneurons and SSNA.

  10. Multimodal Connectivity of Motor Learning-Related Dorsal Premotor Cortex

    PubMed Central

    Hardwick, Robert M.; Lesage, Elise; Eickhoff, Claudia R; Clos, Mareike; Fox, Peter; Eickhoff, Simon B.

    2015-01-01

    The dorsal premotor cortex (dPMC) is a key region for motor learning and sensorimotor integration, yet we have limited understanding of its functional interactions with other regions. Previous work has started to examine functional connectivity in several brain areas using resting state functional connectivity (RSFC) and meta-analytical connectivity modelling (MACM). More recently, structural covariance (SC) has also been proposed as a technique that may also allow delineation of functional connectivity. Here we applied these three approaches to provide a comprehensive characterization of functional connectivity with a seed in the left dPMC that a previous meta-analysis of functional neuroimaging studies has identified as playing a key role in motor learning. Using data from two sources (the Rockland sample, containing resting state data and anatomical scans from 132 participants, and the BrainMap database, which contains peak activation foci from over 10,000 experiments), we conducted independent whole-brain functional connectivity mapping analyses of a dPMC seed. RSFC and MACM revealed similar connectivity maps spanning prefrontal, premotor and parietal regions, while the SC map identified more widespread frontal regions. Analyses indicated a relatively consistent pattern of functional connectivity between RSFC and MACM that was distinct from that identified by SC. Notably, results indicate the seed is functionally connected to areas involved in visuomotor control and executive functions, suggesting the dPMC acts as an interface between motor control and cognition. PMID:26282855

  11. Concurrent TMS to the primary motor cortex augments slow motor learning.

    PubMed

    Narayana, Shalini; Zhang, Wei; Rogers, William; Strickland, Casey; Franklin, Crystal; Lancaster, Jack L; Fox, Peter T

    2014-01-15

    Transcranial magnetic stimulation (TMS) has shown promise as a treatment tool, with one FDA approved use. While TMS alone is able to up- (or down-) regulate a targeted neural system, we argue that TMS applied as an adjuvant is more effective for repetitive physical, behavioral and cognitive therapies, that is, therapies which are designed to alter the network properties of neural systems through Hebbian learning. We tested this hypothesis in the context of a slow motor learning paradigm. Healthy right-handed individuals were assigned to receive 5 Hz TMS (TMS group) or sham TMS (sham group) to the right primary motor cortex (M1) as they performed daily motor practice of a digit sequence task with their non-dominant hand for 4 weeks. Resting cerebral blood flow (CBF) was measured by H2(15)O PET at baseline and after 4 weeks of practice. Sequence performance was measured daily as the number of correct sequences performed, and modeled using a hyperbolic function. Sequence performance increased significantly at 4 weeks relative to baseline in both groups. The TMS group had a significant additional improvement in performance, specifically, in the rate of skill acquisition. In both groups, an improvement in sequence timing and transfer of skills to non-trained motor domains was also found. Compared to the sham group, the TMS group demonstrated increases in resting CBF specifically in regions known to mediate skill learning namely, the M1, cingulate cortex, putamen, hippocampus, and cerebellum. These results indicate that TMS applied concomitantly augments behavioral effects of motor practice, with corresponding neural plasticity in motor sequence learning network. These findings are the first demonstration of the behavioral and neural enhancing effects of TMS on slow motor practice and have direct application in neurorehabilitation where TMS could be applied in conjunction with physical therapy.

  12. Learning and recall of form discriminations during reversible cooling deactivation of ventral-posterior suprasylvian cortex in the cat.

    PubMed

    Lomber, S G; Payne, B R; Cornwell, P

    1996-02-20

    Extrastriate visual cortex of the ventral-posterior suprasylvian gyrus (vPS cortex) of freely behaving cats was reversibly deactivated with cooling to determine its role in performance on a battery of simple or masked two-dimensional pattern discriminations, and three-dimensional object discriminations. Deactivation of vPS cortex by cooling profoundly impaired the ability of the cats to recall the difference between all previously learned pattern and object discriminations. However, the cats' ability to learn or relearn pattern and object discriminations while vPS was deactivated depended upon the nature of the pattern or object and the cats' prior level of exposure to them. During cooling of vPS cortex, the cats could neither learn the novel object discriminations nor relearn a highly familiar masked or partially occluded pattern discrimination, although they could relearn both the highly familiar object and simple pattern discriminations. These cooling-induced deficits resemble those induced by cooling of the topologically equivalent inferotemporal cortex of monkeys and provides evidence that the equivalent regions contribute to visual processing in similar ways.

  13. Modulation of the ∽20-Hz motor-cortex rhythm to passive movement and tactile stimulation

    PubMed Central

    Parkkonen, Eeva; Laaksonen, Kristina; Piitulainen, Harri; Parkkonen, Lauri; Forss, Nina

    2015-01-01

    Background Integration of afferent somatosensory input with motor-cortex output is essential for accurate movements. Prior studies have shown that tactile input modulates motor-cortex excitability, which is reflected in the reactivity of the ∽20-Hz motor-cortex rhythm. ∽20-Hz rebound is connected to inhibition or deactivation of motor cortex whereas suppression has been associated with increased motor cortex activity. Although tactile sense carries important information for controlling voluntary actions, proprioception likely provides the most essential feedback for motor control. Methods To clarify how passive movement modulates motor-cortex excitability, we studied with magnetoencephalography (MEG) the amplitudes and peak latencies of suppression and rebound of the ∽20-Hz rhythm elicited by tactile stimulation and passive movement of right and left index fingers in 22 healthy volunteers. Results Passive movement elicited a stronger and more robust ∽20-Hz rebound than tactile stimulation. In contrast, the suppression amplitudes did not differ between the two stimulus types. Conclusion Our findings suggest that suppression and rebound represent activity of two functionally distinct neuronal populations. The ∽20-Hz rebound to passive movement could be a suitable tool to study the functional state of the motor cortex both in healthy subjects and in patients with motor disorders. PMID:25874163

  14. Competing neural ensembles in motor cortex gate goal-directed motor output

    PubMed Central

    Zagha, Edward; Ge, Xinxin; McCormick, David A.

    2015-01-01

    Summary Unit recordings in behaving animals have revealed the transformation of sensory to motor representations in cortical neurons. However, we still lack basic insights into the mechanisms by which neurons interact to generate such transformations. Here, we study cortical circuits related to behavioral control in mice engaged in a sensory detection task. We recorded neural activity using extracellular and intracellular techniques and analyzed the task-related neural dynamics to reveal underlying circuit processes. Within motor cortex, we find two populations of neurons that have opposing spiking patterns in anticipation of movement. From correlation analyses and circuit modeling, we suggest that these dynamics reflect neural ensembles engaged in a competition. Furthermore, we demonstrate how this competitive circuit may convert a transient, sensory stimulus into a motor command. Together, these data reveal cellular and circuit processes underlying behavioral control, and establish an essential framework for future studies linking cellular activity to behavior. PMID:26593093

  15. Temporal dynamics of cerebellar and motor cortex physiological processes during motor skill learning

    PubMed Central

    Spampinato, D.; Celnik, P.

    2017-01-01

    Learning motor tasks involves distinct physiological processes in the cerebellum (CB) and primary motor cortex (M1). Previous studies have shown that motor learning results in at least two important neurophysiological changes: modulation of cerebellar output mediated in-part by long-term depression of parallel fiber-Purkinje cell synapse and induction of long-term plasticity (LTP) in M1, leading to transient occlusion of additional LTP-like plasticity. However, little is known about the temporal dynamics of these two physiological mechanisms during motor skill learning. Here we use non-invasive brain stimulation to explore CB and M1 mechanisms during early and late motor skill learning in humans. We predicted that early skill acquisition would be proportional to cerebellar excitability (CBI) changes, whereas later stages of learning will result in M1 LTP-like plasticity modifications. We found that early, and not late into skill training, CBI changed. Whereas, occlusion of LTP-like plasticity over M1 occurred only during late, but not early training. These findings indicate a distinct temporal dissociation in the physiological role of the CB and M1 when learning a novel skill. Understanding the role and temporal dynamics of different brain regions during motor learning is critical to device optimal interventions to augment learning. PMID:28091578

  16. Disrupting the ipsilateral motor cortex interferes with training of a complex motor task in older adults.

    PubMed

    Zimerman, Máximo; Heise, Kirstin-F; Gerloff, Christian; Cohen, Leonardo G; Hummel, Friedhelm C

    2014-04-01

    Performance of unimanual movements is associated with bihemispheric activity in the motor cortex in old adults. However, the causal functional role of the ipsilateral MC (iMC) for motor control is still not completely known. Here, the behavioral consequences of interference of the iMC during training of a complex motor skill were tested. Healthy old (58-85 years) and young volunteers (22-35 years) were tested in a double-blind, cross-over, sham-controlled design. Participants attended 2 different study arms with either cathodal transcranial direct current stimulation (ctDCS) or sham concurrent with training. Motor performance was evaluated before, during, 90 min, and 24 h after training. During training, a reduced slope of performance with ctDCS relative to sham was observed in old compared with young (F = 5.8, P = 0.02), with a decrease of correctly rehearsed sequences, an effect that was evident even after 2 consecutive retraining periods without intervention. Furthermore, the older the subject, the more prominent was the disruptive effect of ctDCS (R(2) = 0.50, P = 0.01). These data provide direct evidence for a causal functional link between the iMC and motor skill acquisition in old subjects pointing toward the concept that the recruitment of iMC in old is an adaptive process in response to age-related declines in motor functions.

  17. Role of motor cortex NMDA receptors in learning-dependent synaptic plasticity of behaving mice.

    PubMed

    Hasan, Mazahir T; Hernández-González, Samuel; Dogbevia, Godwin; Treviño, Mario; Bertocchi, Ilaria; Gruart, Agnès; Delgado-García, José M

    2013-01-01

    The primary motor cortex has an important role in the precise execution of learned motor responses. During motor learning, synaptic efficacy between sensory and primary motor cortical neurons is enhanced, possibly involving long-term potentiation and N-methyl-D-aspartate (NMDA)-specific glutamate receptor function. To investigate whether NMDA receptor in the primary motor cortex can act as a coincidence detector for activity-dependent changes in synaptic strength and associative learning, here we generate mice with deletion of the Grin1 gene, encoding the essential NMDA receptor subunit 1 (GluN1), specifically in the primary motor cortex. The loss of NMDA receptor function impairs primary motor cortex long-term potentiation in vivo. Importantly, it impairs the synaptic efficacy between the primary somatosensory and primary motor cortices and significantly reduces classically conditioned eyeblink responses. Furthermore, compared with wild-type littermates, mice lacking NMDA receptors in the [corrected] primary motor cortex show slower learning in Skinner-box tasks. Thus, primary motor cortex NMDA receptors are necessary for activity-dependent synaptic strengthening and associative learning.

  18. Brain correlates to facial motor imagery and its somatotopy in the primary motor cortex.

    PubMed

    Soliman, Ramy S; Lee, Sanghoon; Eun, Seulgi; Mohamed, Abdalla Z; Lee, Jeungchan; Lee, Eunyoung; Makary, Meena M; Kathy Lee, Seung Min; Lee, Hwa-Jin; Choi, Woo Suk; Park, Kyungmo

    2017-03-22

    Motor imagery (MI) has attracted increased interest for motor rehabilitation as many studies have shown that MI shares the same neural networks as motor execution (ME). Nevertheless, MI in terms of facial movement has not been studied extensively; thus, in the present study, we investigated shared neural networks between facial motor imagery (FMI) and facial motor execution (FME). In addition, FMI somatotopy within-face was investigated between the forehead and the mouth. Functional MRI was used to examine 34 healthy individuals with ME and MI paradigms for the forehead and the mouth. The general linear model and a paired t-test were performed to define the facial area in the primary motor cortex (M1) and this area has been used to investigate somatotopy between the forehead and mouth FMI. FMI recruited similar brain motor areas as FME, but showed less neural activity in all activated regions. The facial areas in M1 were distinguishable from other body movements such as finger movement. Further investigation of this area showed that forehead and mouth imagery tended to lack a somatotopic representation for position on M1, and yet had distinct characteristics in terms of neural activity level. FMI showed different characteristics from general MI as the former exclusively activated facial processing areas. In addition, FME and FMI showed different characteristics in terms of BOLD signal level, while sharing the same neural areas. The results imply a potential usefulness of MI training for rehabilitation of facial motor disease considering that forehead and mouth somatotopy showed no clear position difference, and yet showed a significant BOLD signal intensity variation.

  19. Iso-orientation domains in cat visual cortex are arranged in pinwheel-like patterns

    NASA Astrophysics Data System (ADS)

    Bonhoeffer, Tobias; Grinvald, Amiram

    1991-10-01

    THE mammalian cortex is organized in a columnar fashion: neurons lying below each other from the pia to the white matter usually share many functional properties. Across the cortical surface, cells with similar response properties are also clustered together, forming elongated bands or patches. Some response properties, such as orientation preference in the visual cortex, change gradually across the cortical surface forming 'orientation maps'. To determine the precise layout of iso-orientation domains, knowledge of responses not only to one but to many stimulus orientations is essential. Therefore, the exact depiction of orientation maps has been hampered by technical difficulties and remained controversial for almost thirty years. Here we use in vivo optical imaging based on intrinsic signals to gather information on the responses of a piece of cortex to gratings in many different orientations. This complete set of responses then provides detailed information on the structure of the orientation map in a large patch of cortex from area 18 of the cat. We find that cortical regions that respond best to one orientation form highly ordered patches rather than elongated bands. These iso-orientation patches are organized around 'orientation centres', producing pinwheel-like patterns in which the orientation preference of cells is changing continuously across the cortex. We have also analysed our data for fast changes in orientation preference and find that these 'fractures' are limited to the orientation centres. The pinwheels and orientation centres are such a prominent organizational feature that it should be important to understand their development as well as their function in the processing of visual information.

  20. Iso-orientation domains in cat visual cortex are arranged in pinwheel-like patterns.

    PubMed

    Bonhoeffer, T; Grinvald, A

    1991-10-03

    The mammalian cortex is organized in a columnar fashion: neurons lying below each other from the pia to the white matter usually share many functional properties. Across the cortical surface, cells with similar response properties are also clustered together, forming elongated bands or patches. Some response properties, such as orientation preference in the visual cortex, change gradually across the cortical surface forming 'orientation maps'. To determine the precise layout of iso-orientation domains, knowledge of responses not only to one but to many stimulus orientations is essential. Therefore, the exact depiction of orientation maps has been hampered by technical difficulties and remained controversial for almost thirty years. Here we use in vivo optical imaging based on intrinsic signals to gather information on the responses of a piece of cortex to gratings in many different orientations. This complete set of responses then provides detailed information on the structure of the orientation map in a large patch of cortex from area 18 of the cat. We find that cortical regions that respond best to one orientation form highly ordered patches rather than elongated bands. These iso-orientation patches are organized around 'orientation centres', producing pinwheel-like patterns in which the orientation preference of cells is changing continuously across the cortex. We have also analysed our data for fast changes in orientation preference and find that these 'fractures' are limited to the orientation centres. The pinwheels and orientation centres are such a prominent organizational feature that it should be important to understand their development as well as their function in the processing of visual information.

  1. Primary motor cortex contributes to the implementation of implicit value-based rules during motor decisions.

    PubMed

    Derosiere, Gerard; Zénon, Alexandre; Alamia, Andrea; Duque, Julie

    2017-02-01

    In the present study, we investigated the functional contribution of the human primary motor cortex (M1) to motor decisions. Continuous theta burst stimulation (cTBS) was used to alter M1 activity while participants performed a decision-making task in which the reward associated with the subjects' responses (right hand finger movements) depended on explicit and implicit value-based rules. Subjects performed the task over two consecutive days and cTBS occurred in the middle of Day 2, once the subjects were just about to implement implicit rules, in addition to the explicit instructions, to choose their responses, as evident in the control group (cTBS over the right somatosensory cortex). Interestingly, cTBS over the left M1 prevented subjects from implementing the implicit value-based rule while its implementation was enhanced in the group receiving cTBS over the right M1. Hence, cTBS had opposite effects depending on whether it was applied on the contralateral or ipsilateral M1. The use of the explicit value-based rule was unaffected by cTBS in the three groups of subject. Overall, the present study provides evidence for a functional contribution of M1 to the implementation of freshly acquired implicit rules, possibly through its involvement in a cortico-subcortical network controlling value-based motor decisions.

  2. Effect of tactile stimulation on primary motor cortex excitability during action observation combined with motor imagery.

    PubMed

    Tanaka, Megumi; Kubota, Shinji; Onmyoji, Yusuke; Hirano, Masato; Uehara, Kazumasa; Morishita, Takuya; Funase, Kozo

    2015-07-23

    We aimed to investigate the effects of the tactile stimulation to an observer's fingertips at the moment that they saw an object being pinched by another person on the excitability of observer's primary motor cortex (M1) using transcranial magnetic stimulation (TMS). In addition, the above effects were also examined during action observation combined with the motor imagery. Motor evoked potentials (MEP) were evoked from the subjects' right first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles. Electrical stimulation (ES) inducing tactile sensation was delivered to the subjects' first and second fingertips at the moment of pinching action performed by another person. Although neither the ES nor action observation alone had significant effects on the MEP amplitude of the FDI or ADM, the FDI MEP amplitude which acts as the prime mover during pinching was reduced when ES and action observation were combined; however, no such changes were seen in the ADM. Conversely, that reduced FDI MEP amplitude was increased during the motor imagery. These results indicated that the M1 excitability during the action observation of pinching action combined with motor imagery could be enhanced by the tactile stimulation delivered to the observer's fingertips at the moment corresponding to the pinching being observed.

  3. Unilateral nasal obstruction affects motor representation development within the face primary motor cortex in growing rats.

    PubMed

    Abe, Yasunori; Kato, Chiho; Uchima Koecklin, Karin Harumi; Okihara, Hidemasa; Ishida, Takayoshi; Fujita, Koichi; Yabushita, Tadachika; Kokai, Satoshi; Ono, Takashi

    2017-03-23

    Postnatal growth is influenced by genetic and environmental factors. Nasal obstruction during growth alters the electromyographic activity of orofacial muscles. The facial primary motor area represents muscles of the tongue and jaw, which are essential in regulating orofacial motor functions, including chewing and jaw opening. This study aimed to evaluate the effect of chronic unilateral nasal obstruction during growth on the motor representations within the face primary motor cortex (M1). Seventy-two 6-day-old male Wistar rats were randomly divided into control (n = 36) and experimental (n = 36) groups. Rats in the experimental group underwent unilateral nasal obstruction after cauterization of the external nostril at 8 days of age. Intracortical microstimulation (ICMS) mapping was performed when the rats were 5, 7, 9, and 11 weeks old in control and experimental groups (n = 9 per group per time point). Repeated-measures multivariate analysis of variance was used for intergroup and intragroup statistical comparisons. In the control and experimental groups, the total number of positive ICMS sites for the genioglossus and anterior digastric muscles was significantly higher at 5, 7, and 9 weeks, but there was no significant difference between 9 and 11 weeks of age. Moreover, the total number of positive ICMS sites was significantly smaller in the experimental group than in the control at each age. It is possible that nasal obstruction induced the initial changes in orofacial motor behavior in response to the altered respiratory pattern, which eventually contributed to face-M1 neuroplasticity.

  4. Computer-assisted morphometric analysis of intrinsic axon terminals in the supragranular layers of cat striate cortex.

    PubMed

    Gomes-Leal, Walace; Silva, G Jesus; Oliveira, Ricardo B; Picanço-Diniz, Cristovam W

    2002-07-01

    Qualitative and quantitative analyses of terminal arborizations of biocytin-labeled axon terminals were carried out in the cat primary visual cortex (V1). Extracellular iontophoretic injections of 5% biocytin were made into V1 of five adult cats. The animals were perfused 24-48 h after the injections. Labeled-axon fragments were considered to comprise two presumptive groups, according to the qualitative features, thickness, bouton features and appearance of terminal arbors. Forty axon fragments (20 for each presumptive group) were digitized using a microscope with motorized stage and a z-encoder, attached to a microcomputer. The densities of boutons, branching points and axon segments per mm of axon as well as axon segment length were used for comparison of the two groups. The two qualitative groups were confirmed to contain two axon types (I and II), according to cluster analysis of characteristics of the 40 axons in our sample. Forward stepwise discriminant analysis retained two variables as predictors of group membership: axonal length and bouton density. Parametric and non-parametric tests were employed for statistical comparisons (significance at P < 0.01). Type II axon fragments showed the greatest densities of boutons, axonal segments and branching points and the smallest values of length of segments ( P < 0.01). Both the qualitative and quantitative differences found for both types of axons suggest that they belong to different functional classes of neurons, namely spiny (type I) and smooth neurons (type II). Computer-assisted morphometric analysis of individual axon fragments seems to be a suitable approach with which different axon types can be objectively distinguished from each other.

  5. Morphological study of external oblique motor nerves and nuclei in cats.

    PubMed

    Niwa, Masatoshi; Nakayama, Kiyomi; Sasaki, Sei-Ichi

    2008-03-01

    In order to clarify the morphological features of peripheral motor nerves and motoneurons that innervate trunk muscles, the size distribution of external oblique (EO) peripheral motor fibers and motoneurons of the thoracic and the lumbar segments were examined. Histograms of the size distribution of EO motor fibers in peripheral nerves after ganglionectomy clearly had a bimodal distribution of small fiber groups and large fiber groups. It is very likely that small fiber groups correspond to gamma motor fibers and large fiber groups to alpha motor fibers. Gamma and alpha motor fiber groups were separated at 8-14 microm. The average diameter of the gamma and alpha motor fibers were different in each segment. The ratio of gamma and alpha motor fibers was approximately 1:2.0 in the thoracic segments and from 1:1.8 to 1:0.9 in the lumbar segments. Horseradish peroxidase was applied to the central stump of EO nerves, and the size distribution of EO motoneuron cell bodies in the thoracic and the lumbar spinal cords was examined. The size distribution of motoneuron cell bodies was bimodal in one cat (small and large motoneurons) and unimodal in three cats. When the ratio of small motor fibers to large motor fibers in peripheral nerves was applied to that of small motoneurons to large motoneurons, the separation of small and large motoneurons was approximately 40 microm. These results suggest that the morphological characteristics in peripheral nerves of trunk muscles are not reflected in motoneurons.

  6. Deoxyglucose mapping in the cat visual cortex following carotid artery injection and cortical flat-mounting.

    PubMed

    Freeman, B; Löwel, S; Singer, W

    1987-06-01

    Two techniques are described for improving the efficiency of the deoxyglucose metabolic mapping procedure for studies on the cat visual cortex. The first technique involves the bilateral cannulation of the lingual arteries and the symmetrical injection of 2-deoxy-D-[U-14C]glucose in amounts significantly smaller than required with systemic intravenous administration. The second technique is carried out at the end of the stimulation period and involves unfolding the grey matter of the occipital region of the unfixed cortex by blunt dissection (defibrillation) and cutting of the white matter to make a cortical flat-mount: this permits the preparation of large sections parallel to the cortical laminae and thus the interpretation of deoxyglucose uptake patterns in any one lamina over a large area of the visual cortex. The experiments are relatively cheap and the time required to flat-mount the cortices does not seem to produce any significant decrease in spatial resolution of the autoradiograms. In appropriate experiments (published elsewhere) the techniques allow a comparative analysis of the deoxyglucose patterns between hemispheres receiving different visual stimulation.

  7. Rat whisker motor cortex is subdivided into sensory-input and motor-output areas

    PubMed Central

    Smith, Jared B.; Alloway, Kevin D.

    2013-01-01

    Rodent whisking is an exploratory behavior that can be modified by sensory feedback. Consistent with this, many whisker-sensitive cortical regions project to agranular motor [motor cortex (MI)] cortex, but the relative topography of these afferent projections has not been established. Intracortical microstimulation (ICMS) evokes whisker movements that are used to map the functional organization of MI, but no study has compared the whisker-related inputs to MI with the ICMS sites that evoke whisker movements. To elucidate this relationship, anterograde tracers were placed in posterior parietal cortex (PPC) and in the primary somatosensory (SI) and secondary somatosensory (SII) cortical areas so that their labeled projections to MI could be analyzed with respect to ICMS sites that evoke whisker movements. Projections from SI and SII terminate in a narrow zone that marks the transition between the medial agranular (AGm) and lateral agranular (AGl) cortical areas, but PPC projects more medially and terminates in AGm proper. Paired recordings of MI neurons indicate that the region between AGm and AGl is highly responsive to whisker deflections, but neurons in AGm display negligible responses to whisker stimulation. By contrast, AGm microstimulation is more effective in evoking whisker movements than microstimulation of the transitional region between AGm and AGl. The AGm region was also found to contain a larger concentration of corticotectal neurons, which could convey whisker-related information to the facial nucleus. These results indicate that rat whisker MI is comprised of at least two functionally distinct subregions: a sensory processing zone in the transitional region between AGm and AGl, and a motor-output region located more medially in AGm proper. PMID:23372545

  8. Induction of plasticity in the human motor cortex by pairing an auditory stimulus with TMS.

    PubMed

    Sowman, Paul F; Dueholm, Søren S; Rasmussen, Jesper H; Mrachacz-Kersting, Natalie

    2014-01-01

    Acoustic stimuli can cause a transient increase in the excitability of the motor cortex. The current study leverages this phenomenon to develop a method for testing the integrity of auditorimotor integration and the capacity for auditorimotor plasticity. We demonstrate that appropriately timed transcranial magnetic stimulation (TMS) of the hand area, paired with auditorily mediated excitation of the motor cortex, induces an enhancement of motor cortex excitability that lasts beyond the time of stimulation. This result demonstrates for the first time that paired associative stimulation (PAS)-induced plasticity within the motor cortex is applicable with auditory stimuli. We propose that the method developed here might provide a useful tool for future studies that measure auditory-motor connectivity in communication disorders.

  9. Neural population dynamics in human motor cortex during movements in people with ALS.

    PubMed

    Pandarinath, Chethan; Gilja, Vikash; Blabe, Christine H; Nuyujukian, Paul; Sarma, Anish A; Sorice, Brittany L; Eskandar, Emad N; Hochberg, Leigh R; Henderson, Jaimie M; Shenoy, Krishna V

    2015-06-23

    The prevailing view of motor cortex holds that motor cortical neural activity represents muscle or movement parameters. However, recent studies in non-human primates have shown that neural activity does not simply represent muscle or movement parameters; instead, its temporal structure is well-described by a dynamical system where activity during movement evolves lawfully from an initial pre-movement state. In this study, we analyze neuronal ensemble activity in motor cortex in two clinical trial participants diagnosed with Amyotrophic Lateral Sclerosis (ALS). We find that activity in human motor cortex has similar dynamical structure to that of non-human primates, indicating that human motor cortex contains a similar underlying dynamical system for movement generation.

  10. Functional Magnetic Resonance Imaging of Motor Cortex: Hemispheric Asymmetry and Handedness

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Gi; Ashe, James; Hendrich, Kristy; Ellermann, Jutta M.; Merkle, Hellmut; Ugurbil, Kamil; Georgopoulos, Apostolos P.

    1993-07-01

    A hemispheric asymmetry in the functional activation of the human motor cortex during contralateral (C) and ipsilateral (I) finger movements, especially in right-handed subjects, was documented with nuclear magnetic resonance imaging at high field strength (4 tesla). Whereas the right motor cortex was activated mostly during contralateral finger movements in both right-handed (C/I mean area of activation = 36.8) and left-handed (C/I = 29.9) subjects, the left motor cortex was activated substantially during ipsilateral movements in left-handed subjects (C/I = 5.4) and even more so in right-handed subjects (C/I = 1.3).

  11. Interactions between Pain and the Motor Cortex: Insights from Research on Phantom Limb Pain and Complex Regional Pain Syndrome

    PubMed Central

    Léonard, Guillaume

    2011-01-01

    ABSTRACT Purpose: Pain is a significantly disabling problem that often interacts with other deficits during the rehabilitation process. The aim of this paper is to review evidence of interactions between pain and the motor cortex in order to attempt to answer the following questions: (1) Does acute pain interfere with motor-cortex activity? (2) Does chronic pain interfere with motor-cortex activity, and, conversely, does motor-cortex plasticity contribute to chronic pain? (3) Can the induction of motor plasticity by means of motor-cortex stimulation decrease pain? (4) Can motor training result in both motor-cortex reorganization and pain relief? Summary of Key Points: Acute experimental pain has been clearly shown to exert an inhibitory influence over the motor cortex, which can interfere with motor learning capacities. Current evidence also suggests a relationship between chronic pain and motor-cortex reorganization, but it is still unclear whether one causes the other. However, there is growing evidence that interventions aimed at normalizing motor-cortex organization can lead to pain relief. Conclusions: Interactions between pain and the motor cortex are complex, and more studies are needed to understand these interactions in our patients, as well as to develop optimal rehabilitative strategies. PMID:22654236

  12. Increased resting state connectivity between ipsilesional motor cortex and contralesional premotor cortex after transcranial direct current stimulation with physical therapy.

    PubMed

    Chen, Joyce L; Schlaug, Gottfried

    2016-03-16

    Non-invasive stimulation of the brain using transcranial direct current stimulation (tDCS) during motor rehabilitation can improve the recovery of movements in individuals with stroke. However, the neural substrates that underlie the clinical improvements are not well understood. In this proof-of-principle open-label pilot study, five individuals with stroke received 10 sessions of tDCS while undergoing usual care physical/occupational therapy for the arm and hand. Motor impairment as indexed by the Upper Extremity Fugl Meyer assessment was significantly reduced after the intervention. Resting state fMRI connectivity increased between ipsilesional motor cortex and contralesional premotor cortex after the intervention. These findings provide preliminary evidence that the neural underpinnings of tDCS coupled with rehabilitation exercises, may be mediated by interactions between motor and premotor cortex. The latter, of which has been shown to play an important role in the recovery of movements post-stroke. Our data suggest premotor cortex could be tested as a target region for non-invasive brain-stimulation to enhance connectivity between regions that might be beneficial for stroke motor recovery.

  13. Acute aerobic exercise modulates primary motor cortex inhibition.

    PubMed

    Mooney, Ronan A; Coxon, James P; Cirillo, John; Glenny, Helen; Gant, Nicholas; Byblow, Winston D

    2016-12-01

    Aerobic exercise can enhance neuroplasticity although presently the neural mechanisms underpinning these benefits remain unclear. One possible mechanism is through effects on primary motor cortex (M1) function via down-regulation of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). The aim of the present study was to examine how corticomotor excitability (CME) and M1 intracortical inhibition are modulated in response to a single bout of moderate intensity aerobic exercise. Ten healthy right-handed adults were participants. Single- and paired-pulse transcranial magnetic stimulation was applied over left M1 to obtain motor-evoked potentials in the right flexor pollicis brevis. We examined CME, cortical silent period (SP) duration, short- and long-interval intracortical inhibition (SICI, LICI), and late cortical disinhibition (LCD), before and after acute aerobic exercise (exercise session) or an equivalent duration without exercise (control session). Aerobic exercise was performed on a cycle ergometer for 30 min at a workload equivalent to 60 % of maximal cardiorespiratory fitness (VO2 peak; heart rate reserve = 75 ± 3 %, perceived exertion = 13.5 ± 0.7). LICI was reduced at 10 (52 ± 17 %, P = 0.03) and 20 min (27 ± 8 %, P = 0.03) post-exercise compared to baseline (13 ± 4 %). No significant changes in CME, SP duration, SICI or LCD were observed. The present study shows that GABAB-mediated intracortical inhibition may be down-regulated after acute aerobic exercise. The potential effects this may have on M1 plasticity remain to be determined.

  14. Protein Synthesis Inhibition in the Peri-Infarct Cortex Slows Motor Recovery in Rats

    PubMed Central

    Schubring-Giese, Maximilian; Leemburg, Susan; Luft, Andreas Rüdiger; Hosp, Jonas Aurel

    2016-01-01

    Neuroplasticity and reorganization of brain motor networks are thought to enable recovery of motor function after ischemic stroke. Especially in the cortex surrounding the ischemic scar (i.e., peri-infarct cortex), evidence for lasting reorganization has been found at the level of neurons and networks. This reorganization depends on expression of specific genes and subsequent protein synthesis. To test the functional relevance of the peri-infarct cortex for recovery we assessed the effect of protein synthesis inhibition within this region after experimental stroke. Long-Evans rats were trained to perform a skilled-reaching task (SRT) until they reached plateau performance. A photothrombotic stroke was induced in the forelimb representation of the primary motor cortex (M1) contralateral to the trained paw. The SRT was re-trained after stroke while the protein synthesis inhibitor anisomycin (ANI) or saline were injected into the peri-infarct cortex through implanted cannulas. ANI injections reduced protein synthesis within the peri-infarct cortex by 69% and significantly impaired recovery of reaching performance through re-training. Improvement of motor performance within a single training session remained intact, while improvement between training sessions was impaired. ANI injections did not affect infarct size. Thus, protein synthesis inhibition within the peri-infarct cortex impairs recovery of motor deficits after ischemic stroke by interfering with consolidation of motor memory between training sessions but not short-term improvements within one session. PMID:27314672

  15. Volumetric Effects of Motor Cortex Injury on Recovery of Dexterous Movements

    PubMed Central

    Darling, Warren G.; Pizzimenti, Marc A.; Rotella, Diane L.; Peterson, Clayton R.; Hynes, Stephanie M.; Ge, Jizhi; Solon, Kathryn; McNeal, David W.; Stilwell-Morecraft, Kimberly S.; Morecraft, Robert J.

    2009-01-01

    Due to the heterogeneous nature of most brain injuries, the contributions of gray and white matter involvement to motor deficits and recovery potential remain obscure. We tested the hypothesis that duration of hand motor impairment and recovery of skilled arm and hand motor function depends on the volume of gray and white matter damage of the frontal lobe. Lesions of the primary motor cortex (M1), M1 + lateral premotor cortex (LPMC), M1 + LPMC + supplementary motor cortex (M2) or multi-focal lesions affecting motor areas and medial prefrontal cortex were evaluated in rhesus monkeys. Fine hand motor function was quantitatively assessed pre-lesion and for 3–12 months post-lesion using two motor tests. White and gray matter lesion volumes were determined using histological and quantitative methods. Regression analyses showed that duration of fine hand motor impairment was strongly correlated (R2 > 0.8) with the volume of gray and white matter lesions, with white matter lesion volume being the primary predictor of impairment duration. Level of recovery of fine hand motor skill was also well correlated (R2 > 0.5) with gray and white matter lesion volume. In some monkeys post-lesion skill exceeded pre-lesion skill in one or both motor tasks demonstrating that continued post-injury task practice can improve motor performance after localized loss of frontal motor cortex. These findings will assist in interpreting acute motor deficits, predicting the time course and expected level of functional recovery, and designing therapeutic strategies in patients with localized frontal lobe injury or neurosurgical resection. PMID:19679127

  16. From modular to centralized organization of synchronization in functional areas of the cat cerebral cortex.

    PubMed

    Gómez-Gardeñes, Jesús; Zamora-López, Gorka; Moreno, Yamir; Arenas, Alex

    2010-08-26

    Recent studies have pointed out the importance of transient synchronization between widely distributed neural assemblies to understand conscious perception. These neural assemblies form intricate networks of neurons and synapses whose detailed map for mammals is still unknown and far from our experimental capabilities. Only in a few cases, for example the C. elegans, we know the complete mapping of the neuronal tissue or its mesoscopic level of description provided by cortical areas. Here we study the process of transient and global synchronization using a simple model of phase-coupled oscillators assigned to cortical areas in the cerebral cat cortex. Our results highlight the impact of the topological connectivity in the developing of synchronization, revealing a transition in the synchronization organization that goes from a modular decentralized coherence to a centralized synchronized regime controlled by a few cortical areas forming a Rich-Club connectivity pattern.

  17. Motor cortex stimulation for Parkinson's disease: a modelling study

    NASA Astrophysics Data System (ADS)

    Zwartjes, Daphne G. M.; Heida, Tjitske; Feirabend, Hans K. P.; Janssen, Marcus L. F.; Visser-Vandewalle, Veerle; Martens, Hubert C. F.; Veltink, Peter H.

    2012-10-01

    Chronic motor cortex stimulation (MCS) is currently being investigated as a treatment method for Parkinson's disease (PD). Unfortunately, the underlying mechanisms of this treatment are unclear and there are many uncertainties regarding the most effective stimulation parameters and electrode configuration. In this paper, we present a MCS model with a 3D representation of several axonal populations. The model predicts that the activation of either the basket cell or pyramidal tract (PT) type axons is involved in the clinical effect of MCS. We propose stimulation protocols selectively targeting one of these two axon types. To selectively target the basket cell axons, our simulations suggest using either cathodal or bipolar stimulation with the electrode strip placed perpendicular rather than parallel to the gyrus. Furthermore, selectivity can be increased by using multiple cathodes. PT type axons can be selectively targeted with anodal stimulation using electrodes with large contact sizes. Placing the electrode epidurally is advisable over subdural placement. These selective protocols, when practically implemented, can be used to further test which axon type should be activated for clinically effective MCS and can subsequently be applied to optimize treatment. In conclusion, this paper increases insight into the neuronal population involved in the clinical effect of MCS on PD and proposes strategies to improve this therapy.

  18. A threat to a virtual hand elicits motor cortex activation.

    PubMed

    González-Franco, Mar; Peck, Tabitha C; Rodríguez-Fornells, Antoni; Slater, Mel

    2014-03-01

    We report an experiment where participants observed an attack on their virtual body as experienced in an immersive virtual reality (IVR) system. Participants sat by a table with their right hand resting upon it. In IVR, they saw a virtual table that was registered with the real one, and they had a virtual body that substituted their real body seen from a first person perspective. The virtual right hand was collocated with their real right hand. Event-related brain potentials were recorded in two conditions, one where the participant's virtual hand was attacked with a knife and a control condition where the knife only struck the virtual table. Significantly greater P450 potentials were obtained in the attack condition confirming our expectations that participants had a strong illusion of the virtual hand being their own, which was also strongly supported by questionnaire responses. Higher levels of subjective virtual hand ownership correlated with larger P450 amplitudes. Mu-rhythm event-related desynchronization in the motor cortex and readiness potential (C3-C4) negativity were clearly observed when the virtual hand was threatened-as would be expected, if the real hand was threatened and the participant tried to avoid harm. Our results support the idea that event-related potentials may provide a promising non-subjective measure of virtual embodiment. They also support previous experiments on pain observation and are placed into context of similar experiments and studies of body perception and body ownership within cognitive neuroscience.

  19. Functional Networks of Parvalbumin-immunoreactive Neurons in Cat Auditory Cortex

    PubMed Central

    Yuan, Kexin; Shih, Jonathan Y.; Winer, Jeffery A.; Schreiner, Christoph E.

    2011-01-01

    Inhibitory interneurons constitute ~20% of auditory cortical cells and are essential for shaping sensory processing. Connectivity patterns of interneurons in relation to functional organization principles are not well understood. We contrasted the connection patterns of parvalbumin-immunoreactive cells in two functionally distinct cortical regions, the tonotopic, narrowly frequency-tuned module (cNB) of cat central primary auditory cortex (AI), and the non-tonotopic, broadly tuned second auditory field (AII). Interneuronal connectivity patterns and laminar distribution were identified by combining a retrograde tracer (WAHG) with labeling of the Ca2+ binding protein, parvalbumin (Pv), a marker for the GABAergic interneurons usually described physiologically as fast-spiking neurons. In AI, PV+ cells constituted 13% of the retrograde labeled cells in the immediate vicinity of the injection site, compared to 10% in AII. The retrograde labeling of Pv+ cells along isofrequency countours was confined to cNB. The spatial spread of labeled excitatory neurons in AI was more than twice that found for Pv+ cells. By contrast, in AII, the spread of Pv+ cells was nearly equal to that of excitatory neurons. The retrograde labeling of Pv+ cells was anisotropic in AI and isotropic in AII. This demonstration of inhibitory networks in auditory cortex reveals that the connections of cat GABAergic AI and AII cells follow different anatomical plans and, thus, contribute differently to the shaping of neural response properties. The finding that local connectivity of parvalbumin-immunoreactive neurons in AI is closely aligned with spectral integration properties demonstrates the critical role of inhibition in creating distinct processing modules in AI. PMID:21917816

  20. Cats

    MedlinePlus

    ... Patients Infants and Young Children Publications & Materials Announcements Cats Recommend on Facebook Tweet Share Compartir Overview Diseases ... hand washing whenever you play or work with cats Wash your hands with soap and running water ...

  1. Spectral Integration Plasticity in Cat Auditory Cortex Induced by Perceptual Training

    PubMed Central

    Keeling, M. Diane; Calhoun, Barbara M.; Krüger, Katharina; Polley, Daniel B.; Schreiner, Christoph E.

    2008-01-01

    We investigated the ability of cats to discriminate differences between vowel-like spectra, assessed their discrimination ability over time, and compared spectral receptive fields in primary auditory cortex (AI) of trained and untrained cats. Animals were trained to discriminate changes in the spectral envelope of a broad-band harmonic complex in a 2-alternative forced choice procedure. The standard stimulus was an acoustic grating consisting of a harmonic complex with a sinusoidally modulated spectral envelope ('ripple spectrum'). The spacing of spectral peaks was conserved at 1, 2, or 2.66 peaks/octave. Animals were trained to detect differences in the frequency location of energy peaks, corresponding to changes in the spectral envelope phase. Average discrimination thresholds improved continuously during the course of the testing from phase-shifts of 96° at the beginning to 44° after 4–6 months of training. Responses of AI single units and small groups of neurons to pure tones and ripple spectra were modified during perceptual discrimination training with vowel-like ripple stimuli. The transfer function for spectral envelope frequencies narrowed and the tuning for pure tones sharpened significantly in discriminant versus naive animals. By contrast, control animals that used the ripple spectra only in a lateralization task showed broader ripple transfer functions and narrower pure-tone tuning than naïve animals. PMID:17896103

  2. The Changes of c-Fos Expression by Motor Cortex Stimulation in the Deafferentation Pain Model

    PubMed Central

    KUDO, Kanae; TAKAHASHI, Toshio; SUZUKI, Shigeharu

    2014-01-01

    The effect of motor cortex stimulation (MCS) therapy for deafferentation pain was evaluated based on c-Fos, a known pain marker. Nineteen mature cats weighing 1.5–3.5 kg were used. Cats were divided into three groups: a deafferentation pain group in which the left trigeminal ganglion was destroyed, an MCS group in which MCS was used following destruction of the trigeminal ganglion, and a control group. Sites and levels of c-Fos expression were examined immunohistochemically. The percentage of c-Fos-positive cells in the left spinal nucleus of the trigeminus, the bilateral insula, and the bilateral operculum increased in both the deafferentation pain and the MCS groups. There were no statistically significant differences between these groups. In the cingulate gyrus, the percentage of c-Fos-positive cells increased bilaterally in the deafferentation pain group and the MCS group, but the increase was greater in the MCS group. The increase in c-Fos-positive cells in the left spinal nucleus of the trigeminus in the deafferentation group may reflect reported electrical hyperactivity. The cingulate gyrus, insula, and parietal operculum were activated after deafferentation. This change (increase in c-Fos positive cells) is related to the development of deafferentation pain. Pain relief due to MCS is not dependent on the suppression of the activated left spinal nucleus of the trigeminus or the descending analgesic mechanism of the brain stem. Activation of the cingulate gyrus appears to be a factor in the analgesic mechanism of MCS. PMID:24965534

  3. Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.

    PubMed

    Fallon, James B; Shepherd, Robert K; Nayagam, David A X; Wise, Andrew K; Heffer, Leon F; Landry, Thomas G; Irvine, Dexter R F

    2014-09-01

    We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two groups received up to 8 months of either low- or high-rate (50 or 500 pulses per second per electrode, respectively) stimulation from a clinical cochlear implant, initiated at 10 weeks of age. Deafness of 7-13 months duration had no effect on the duration of post-onset response suppression, latency, latency jitter, or the stimulus repetition rate at which units responded maximally (best repetition rate), but resulted in a statistically significant reduction in the ability of units to respond to every stimulus in a train (maximum following rate). None of the temporal response characteristics of the low-rate group differed from those in acutely deafened controls. In contrast, high-rate stimulation had diverse effects: it resulted in decreased suppression duration, longer latency and greater jitter relative to all other groups, and an increase in best repetition rate and cut-off rate relative to acutely deafened controls. The minimal effects of moderate-duration deafness on temporal processing in the present study are in contrast to its previously-reported pronounced effects on cochleotopy. Much longer periods of deafness have been reported to result in significant changes in temporal processing, in accord with the fact that duration of deafness is a major factor influencing outcome in human cochlear implantees.

  4. 3D visualization of movements can amplify motor cortex activation during subsequent motor imagery

    PubMed Central

    Sollfrank, Teresa; Hart, Daniel; Goodsell, Rachel; Foster, Jonathan; Tan, Tele

    2015-01-01

    A repetitive movement practice by motor imagery (MI) can influence motor cortical excitability in the electroencephalogram (EEG). This study investigated if a realistic visualization in 3D of upper and lower limb movements can amplify motor related potentials during subsequent MI. We hypothesized that a richer sensory visualization might be more effective during instrumental conditioning, resulting in a more pronounced event related desynchronization (ERD) of the upper alpha band (10–12 Hz) over the sensorimotor cortices thereby potentially improving MI based brain-computer interface (BCI) protocols for motor rehabilitation. The results show a strong increase of the characteristic patterns of ERD of the upper alpha band components for left and right limb MI present over the sensorimotor areas in both visualization conditions. Overall, significant differences were observed as a function of visualization modality (VM; 2D vs. 3D). The largest upper alpha band power decrease was obtained during MI after a 3-dimensional visualization. In total in 12 out of 20 tasks the end-user of the 3D visualization group showed an enhanced upper alpha ERD relative to 2D VM group, with statistical significance in nine tasks.With a realistic visualization of the limb movements, we tried to increase motor cortex activation during subsequent MI. The feedback and the feedback environment should be inherently motivating and relevant for the learner and should have an appeal of novelty, real-world relevance or aesthetic value (Ryan and Deci, 2000; Merrill, 2007). Realistic visual feedback, consistent with the participant’s MI, might be helpful for accomplishing successful MI and the use of such feedback may assist in making BCI a more natural interface for MI based BCI rehabilitation. PMID:26347642

  5. 3D visualization of movements can amplify motor cortex activation during subsequent motor imagery.

    PubMed

    Sollfrank, Teresa; Hart, Daniel; Goodsell, Rachel; Foster, Jonathan; Tan, Tele

    2015-01-01

    A repetitive movement practice by motor imagery (MI) can influence motor cortical excitability in the electroencephalogram (EEG). This study investigated if a realistic visualization in 3D of upper and lower limb movements can amplify motor related potentials during subsequent MI. We hypothesized that a richer sensory visualization might be more effective during instrumental conditioning, resulting in a more pronounced event related desynchronization (ERD) of the upper alpha band (10-12 Hz) over the sensorimotor cortices thereby potentially improving MI based brain-computer interface (BCI) protocols for motor rehabilitation. The results show a strong increase of the characteristic patterns of ERD of the upper alpha band components for left and right limb MI present over the sensorimotor areas in both visualization conditions. Overall, significant differences were observed as a function of visualization modality (VM; 2D vs. 3D). The largest upper alpha band power decrease was obtained during MI after a 3-dimensional visualization. In total in 12 out of 20 tasks the end-user of the 3D visualization group showed an enhanced upper alpha ERD relative to 2D VM group, with statistical significance in nine tasks.With a realistic visualization of the limb movements, we tried to increase motor cortex activation during subsequent MI. The feedback and the feedback environment should be inherently motivating and relevant for the learner and should have an appeal of novelty, real-world relevance or aesthetic value (Ryan and Deci, 2000; Merrill, 2007). Realistic visual feedback, consistent with the participant's MI, might be helpful for accomplishing successful MI and the use of such feedback may assist in making BCI a more natural interface for MI based BCI rehabilitation.

  6. Relating cluster and population responses to natural sounds and tonal stimuli in cat primary auditory cortex.

    PubMed

    Rotman, Y; Bar-Yosef, O; Nelken, I

    2001-02-01

    Most information about neuronal properties in primary auditory cortex (AI) has been gathered using simple artificial sounds such as pure tones and broad-band noise. These sounds are very different from the natural sounds that are processed by the auditory system in real world situations. In an attempt to bridge this gap, simple tonal stimuli and a standard set of six natural sounds were used to create models relating the responses of neuronal clusters in AI of barbiturate-anesthetized cats to the two classes of stimuli. A significant correlation was often found between the response to the separate frequency components of the natural sounds and the response to the natural sound itself. At the population level, this correlation resulted in a rate profile that represented robustly the spectral profiles of the natural sounds. There was however a significant scatter in the responses to the natural sound around the predictions based on the responses to tonal stimuli. Going the other way, in order to understand better the non-linearities in the responses to natural sounds, responses of neuronal clusters were characterized using second order Volterra kernel analysis of their responses to natural sounds. This characterization predicted reasonably well the amplitude of the response to other natural sounds, but could not reproduce the responses to tonal stimuli. Thus, second order non-linear characterizations, at least those using the Volterra kernel model, do not interpolate well between responses to tones and to natural sounds in auditory cortex.

  7. A linear model fails to predict orientation selectivity of cells in the cat visual cortex.

    PubMed Central

    Volgushev, M; Vidyasagar, T R; Pei, X

    1996-01-01

    1. Postsynaptic potentials (PSPs) evoked by visual stimulation in simple cells in the cat visual cortex were recorded using in vivo whole-cell technique. Responses to small spots of light presented at different positions over the receptive field and responses to elongated bars of different orientations centred on the receptive field were recorded. 2. To test whether a linear model can account for orientation selectivity of cortical neurones, responses to elongated bars were compared with responses predicted by a linear model from the receptive field map obtained from flashing spots. 3. The linear model faithfully predicted the preferred orientation, but not the degree of orientation selectivity or the sharpness of orientation tuning. The ratio of optimal to non-optimal responses was always underestimated by the model. 4. Thus non-linear mechanisms, which can include suppression of non-optimal responses and/or amplification of optimal responses, are involved in the generation of orientation selectivity in the primary visual cortex. PMID:8930828

  8. Subthalamic Nucleus Stimulation Modulates Motor Cortex Oscillatory Activity in Parkinson's Disease

    ERIC Educational Resources Information Center

    Devos, D.; Labyt, E.; Derambure, P.; Bourriez, J. L.; Cassim, F.; Reyns, N.; Blond, S.; Guieu, J. D.; Destee, A.; Defebvre, L.

    2004-01-01

    In Parkinson's disease, impaired motor preparation has been related to an increased latency in the appearance of movement-related desynchronization (MRD) throughout the contralateral primary sensorimotor (PSM) cortex. Internal globus pallidus (GPi) stimulation improved movement desynchronization over the PSM cortex during movement execution but…

  9. Subtype-specific plasticity of inhibitory circuits in motor cortex during motor learning

    PubMed Central

    Chen, Simon X.; Kim, An Na; Peters, Andrew J.; Komiyama, Takaki

    2015-01-01

    Motor skill learning induces long-lasting reorganization of dendritic spines, major sites of excitatory synapses, in the motor cortex. However, mechanisms that regulate these excitatory synaptic changes remain poorly understood. Here using in vivo two-photon imaging in awake mice, we found that learning-induced spine reorganization of L2/3 excitatory neurons occurs in the distal branches of their apical dendrites in L1 but not in the perisomatic dendrites. This compartment-specific spine reorganization coincided with subtype-specific plasticity of local inhibitory circuits. Somatostatin-expressing inhibitory neurons (SOM-INs) that mainly inhibit distal dendrites of excitatory neurons showed a decrease in axonal boutons immediately after the training begins, whereas parvalbumin-expressing inhibitory neurons (PV-INs) that mainly inhibit perisomatic regions of excitatory neurons exhibited a gradual increase in the axonal boutons during training. Optogenetic enhancement and suppression of SOM-IN activity during training destabilized and hyper-stabilized spines, respectively, and both manipulations impaired the learning of stereotyped movements. Our results identify SOM inhibition of distal dendrites as a key regulator of learning-related changes in excitatory synapses and the acquisition of motor skills. PMID:26098758

  10. Absolute Depth Sensitivity in Cat Primary Visual Cortex under Natural Viewing Conditions

    PubMed Central

    Pigarev, Ivan N.; Levichkina, Ekaterina V.

    2016-01-01

    Mechanisms of 3D perception, investigated in many laboratories, have defined depth either relative to the fixation plane or to other objects in the visual scene. It is obvious that for efficient perception of the 3D world, additional mechanisms of depth constancy could operate in the visual system to provide information about absolute distance. Neurons with properties reflecting some features of depth constancy have been described in the parietal and extrastriate occipital cortical areas. It has also been shown that, for some neurons in the visual area V1, responses to stimuli of constant angular size differ at close and remote distances. The present study was designed to investigate whether, in natural free gaze viewing conditions, neurons tuned to absolute depths can be found in the primary visual cortex (area V1). Single-unit extracellular activity was recorded from the visual cortex of waking cats sitting on a trolley in front of a large screen. The trolley was slowly approaching the visual scene, which consisted of stationary sinusoidal gratings of optimal orientation rear-projected over the whole surface of the screen. Each neuron was tested with two gratings, with spatial frequency of one grating being twice as high as that of the other. Assuming that a cell is tuned to a spatial frequency, its maximum response to the grating with a spatial frequency twice as high should be shifted to a distance half way closer to the screen in order to attain the same size of retinal projection. For hypothetical neurons selective to absolute depth, location of the maximum response should remain at the same distance irrespective of the type of stimulus. It was found that about 20% of neurons in our experimental paradigm demonstrated sensitivity to particular distances independently of the spatial frequencies of the gratings. We interpret these findings as an indication of the use of absolute depth information in the primary visual cortex. PMID:27547179

  11. Absolute Depth Sensitivity in Cat Primary Visual Cortex under Natural Viewing Conditions.

    PubMed

    Pigarev, Ivan N; Levichkina, Ekaterina V

    2016-01-01

    Mechanisms of 3D perception, investigated in many laboratories, have defined depth either relative to the fixation plane or to other objects in the visual scene. It is obvious that for efficient perception of the 3D world, additional mechanisms of depth constancy could operate in the visual system to provide information about absolute distance. Neurons with properties reflecting some features of depth constancy have been described in the parietal and extrastriate occipital cortical areas. It has also been shown that, for some neurons in the visual area V1, responses to stimuli of constant angular size differ at close and remote distances. The present study was designed to investigate whether, in natural free gaze viewing conditions, neurons tuned to absolute depths can be found in the primary visual cortex (area V1). Single-unit extracellular activity was recorded from the visual cortex of waking cats sitting on a trolley in front of a large screen. The trolley was slowly approaching the visual scene, which consisted of stationary sinusoidal gratings of optimal orientation rear-projected over the whole surface of the screen. Each neuron was tested with two gratings, with spatial frequency of one grating being twice as high as that of the other. Assuming that a cell is tuned to a spatial frequency, its maximum response to the grating with a spatial frequency twice as high should be shifted to a distance half way closer to the screen in order to attain the same size of retinal projection. For hypothetical neurons selective to absolute depth, location of the maximum response should remain at the same distance irrespective of the type of stimulus. It was found that about 20% of neurons in our experimental paradigm demonstrated sensitivity to particular distances independently of the spatial frequencies of the gratings. We interpret these findings as an indication of the use of absolute depth information in the primary visual cortex.

  12. Inhibition of classically conditioned eyeblink responses by stimulation of the cerebellar cortex in the decerebrate cat.

    PubMed

    Hesslow, G

    1994-04-15

    The purpose of the present study was to test the hypothesis that neurones in the anterior interpositus nucleus, under the control of Purkinje cells in the c1 and c3 zones of the cerebellar cortex, exert some control over classically conditioned responses. In particular, the experiments were designed to determine whether the cerebellar control of conditioned and unconditioned responses is different. The experiments were performed on cats decerebrated rostral to the red nucleus under halothane anaesthesia. The cats were conditioned using either a 1000 Hz tone or trains of stimuli through the skin of the proximal forelimb as the conditioned stimulus, and periorbital electrical stimulation as the unconditioned stimulus. A large proportion of the animals acquired conditioned responses at normal rates. It could be shown that these were true conditioned responses and did not result from sensitization or pseudoconditioning. For instance, unpaired presentations of conditioned and unconditioned stimuli caused rapid extinction. Cerebellar areas controlling eyeblink were identified by recording climbing fibre responses in the cerebellar cortex and recording EMG activity in the eyelid evoked by stimulation of the cerebellar cortex. When single shocks of 40-70 microA were applied to these areas during the emission of conditioned eyeblink responses, the latter were strongly inhibited. The inhibition had a latency of about 10 ms and a duration of 25-75 ms. It was shown that this inhibition of the conditioned responses was topographically specific and could only be evoked from cortical sites identified as controlling eyeblink. Stimulation of the periphery of an eyeblink area caused little or no inhibition. The effect of cortical stimulation on unconditioned reflex responses in the orbicularis oculi muscle was also tested. Some inhibition of unconditioned responses was observed, but quantitative analysis showed that this inhibition was considerably weaker than the corresponding

  13. Inhibition of classically conditioned eyeblink responses by stimulation of the cerebellar cortex in the decerebrate cat.

    PubMed Central

    Hesslow, G

    1994-01-01

    The purpose of the present study was to test the hypothesis that neurones in the anterior interpositus nucleus, under the control of Purkinje cells in the c1 and c3 zones of the cerebellar cortex, exert some control over classically conditioned responses. In particular, the experiments were designed to determine whether the cerebellar control of conditioned and unconditioned responses is different. The experiments were performed on cats decerebrated rostral to the red nucleus under halothane anaesthesia. The cats were conditioned using either a 1000 Hz tone or trains of stimuli through the skin of the proximal forelimb as the conditioned stimulus, and periorbital electrical stimulation as the unconditioned stimulus. A large proportion of the animals acquired conditioned responses at normal rates. It could be shown that these were true conditioned responses and did not result from sensitization or pseudoconditioning. For instance, unpaired presentations of conditioned and unconditioned stimuli caused rapid extinction. Cerebellar areas controlling eyeblink were identified by recording climbing fibre responses in the cerebellar cortex and recording EMG activity in the eyelid evoked by stimulation of the cerebellar cortex. When single shocks of 40-70 microA were applied to these areas during the emission of conditioned eyeblink responses, the latter were strongly inhibited. The inhibition had a latency of about 10 ms and a duration of 25-75 ms. It was shown that this inhibition of the conditioned responses was topographically specific and could only be evoked from cortical sites identified as controlling eyeblink. Stimulation of the periphery of an eyeblink area caused little or no inhibition. The effect of cortical stimulation on unconditioned reflex responses in the orbicularis oculi muscle was also tested. Some inhibition of unconditioned responses was observed, but quantitative analysis showed that this inhibition was considerably weaker than the corresponding

  14. Putting an "end" to the motor cortex representations of action words.

    PubMed

    de Zubicaray, Greig; Arciuli, Joanne; McMahon, Katie

    2013-11-01

    Language processing is an example of implicit learning of multiple statistical cues that provide probabilistic information regarding word structure and use. Much of the current debate about language embodiment is devoted to how action words are represented in the brain, with motor cortex activity evoked by these words assumed to selectively reflect conceptual content and/or its simulation. We investigated whether motor cortex activity evoked by manual action words (e.g., caress) might reflect sensitivity to probabilistic orthographic-phonological cues to grammatical category embedded within individual words. We first review neuroimaging data demonstrating that nonwords evoke activity much more reliably than action words along the entire motor strip, encompassing regions proposed to be action category specific. Using fMRI, we found that disyllabic words denoting manual actions evoked increased motor cortex activity compared with non-body-part-related words (e.g., canyon), activity which overlaps that evoked by observing and executing hand movements. This result is typically interpreted in support of language embodiment. Crucially, we also found that disyllabic nonwords containing endings with probabilistic cues predictive of verb status (e.g., -eve) evoked increased activity compared with nonwords with endings predictive of noun status (e.g., -age) in the identical motor area. Thus, motor cortex responses to action words cannot be assumed to selectively reflect conceptual content and/or its simulation. Our results clearly demonstrate motor cortex activity reflects implicit processing of ortho-phonological statistical regularities that help to distinguish a word's grammatical class.

  15. The role of hearing ability and speech distortion in the facilitation of articulatory motor cortex.

    PubMed

    Nuttall, Helen E; Kennedy-Higgins, Daniel; Devlin, Joseph T; Adank, Patti

    2017-01-08

    Excitability of articulatory motor cortex is facilitated when listening to speech in challenging conditions. Beyond this, however, we have little knowledge of what listener-specific and speech-specific factors engage articulatory facilitation during speech perception. For example, it is unknown whether speech motor activity is independent or dependent on the form of distortion in the speech signal. It is also unknown if speech motor facilitation is moderated by hearing ability. We investigated these questions in two experiments. We applied transcranial magnetic stimulation (TMS) to the lip area of primary motor cortex (M1) in young, normally hearing participants to test if lip M1 is sensitive to the quality (Experiment 1) or quantity (Experiment 2) of distortion in the speech signal, and if lip M1 facilitation relates to the hearing ability of the listener. Experiment 1 found that lip motor evoked potentials (MEPs) were larger during perception of motor-distorted speech that had been produced using a tongue depressor, and during perception of speech presented in background noise, relative to natural speech in quiet. Experiment 2 did not find evidence of motor system facilitation when speech was presented in noise at signal-to-noise ratios where speech intelligibility was at 50% or 75%, which were significantly less severe noise levels than used in Experiment 1. However, there was a significant interaction between noise condition and hearing ability, which indicated that when speech stimuli were correctly classified at 50%, speech motor facilitation was observed in individuals with better hearing, whereas individuals with relatively worse but still normal hearing showed more activation during perception of clear speech. These findings indicate that the motor system may be sensitive to the quantity, but not quality, of degradation in the speech signal. Data support the notion that motor cortex complements auditory cortex during speech perception, and point to a role

  16. Laminar and regional distribution of galanin binding sites in cat and monkey visual cortex determined by in vitro receptor autoradiography

    SciTech Connect

    Rosier, A.M.; Vandesande, F.; Orban, G.A. )

    1991-03-08

    The distribution of galanin (GAL) binding sites in the visual cortex of cat and monkey was determined by autoradiographic visualization of ({sup 125}I)-GAL binding to tissue sections. Binding conditions were optimized and, as a result, the binding was saturable and specific. In cat visual cortex, GAL binding sites were concentrated in layers I, IVc, V, and VI. Areas 17, 18, and 19 exhibited a similar distribution pattern. In monkey primary visual cortex, the highest density of GAL binding sites was observed in layers II/III, lower IVc, and upper V. Layers IVA and VI contained moderate numbers of GAL binding sites, while layer I and the remaining parts of layer IV displayed the lowest density. In monkey secondary visual cortex, GAL binding sites were mainly concentrated in layers V-VI. Layer IV exhibited a moderate density, while the supragranular layers contained the lowest proportion of GAL binding sites. In both cat and monkey, we found little difference between regions subserving central and those subserving peripheral vision. Similarities in the distribution of GAL and acetylcholine binding sites are discussed.

  17. Activation of the motor cortex during phasic rapid eye movement sleep

    PubMed Central

    De Carli, Fabrizio; Proserpio, Paola; Morrone, Elisa; Sartori, Ivana; Ferrara, Michele; Gibbs, Steve Alex; De Gennaro, Luigi; Lo Russo, Giorgio

    2016-01-01

    When dreaming during rapid eye movement (REM) sleep, we can perform complex motor behaviors while remaining motionless. How the motor cortex behaves during this state remains unknown. Here, using intracerebral electrodes sampling the human motor cortex in pharmacoresistant epileptic patients, we report a pattern of electroencephalographic activation during REM sleep similar to that observed during the performance of a voluntary movement during wakefulness. This pattern is present during phasic REM sleep but not during tonic REM sleep, the latter resembling relaxed wakefulness. This finding may help clarify certain phenomenological aspects observed in REM sleep behavior disorder. Ann Neurol 2016;79:326–330 PMID:26575212

  18. Effect of hindlimb unloading on stereological parameters of the motor cortex and hippocampus in male rats.

    PubMed

    Salehi, Mohammad Saied; Mirzaii-Dizgah, Iraj; Vasaghi-Gharamaleki, Behnoosh; Zamiri, Mohammad Javad

    2016-11-09

    Hindlimb unloading (HU) can cause motion and cognition dysfunction, although its cellular and molecular mechanisms are not well understood. The aim of the present study was to determine the stereological parameters of the brain areas involved in motion (motor cortex) and spatial learning - memory (hippocampus) under an HU condition. Sixteen adult male rats, kept under a 12 : 12 h light-dark cycle, were divided into two groups of freely moving (n=8) and HU (n=8) rats. The volume of motor cortex and hippocampus, the numerical cell density of neurons in layers I, II-III, V, and VI of the motor cortex, the entire motor cortex as well as the primary motor cortex, and the numerical density of the CA1, CA3, and dentate gyrus subregions of the hippocampus were estimated. No significant differences were observed in the evaluated parameters. Our results thus indicated that motor cortical and hippocampal atrophy and cell loss may not necessarily be involved in the motion and spatial learning memory impairment in the rat.

  19. Studies of sensory and motor cortex physiology: with observations on akinesia in Parkinson's disease.

    PubMed

    Hallett, M; Cohen, L G; Bierner, S M

    1991-01-01

    Magnetic stimulation of the brain can be used to investigate sensory and motor physiology and pathophysiology in intact humans. Although uncommon, it is possible for magnetic stimulation over sensorimotor cortex to produce paresthesis. With magnetic stimulation, it is also possible to block the conscious sensation of an electrical shock delivered to the index finger. The magnetic stimulus must be delivered in the interval from 300 msec before to 200 msec after the cutaneous shock and must be delivered over the contralateral hand region of the sensorimotor cortex. In a reaction time situation, the expected voluntary response may be delayed by a magnetic stimulus delivered over the sensorimotor cortex just before the movement. With the use of a relatively weak magnetic stimulus that does not produce a motor evoked potential (MEP) when the body part is at rest, but that will produce a response when the body part is activated, the reaction time can be divided into two periods. In the first period, there is no MEP and the motor cortex remains 'inexcitable'. In the second period, there is a gradual increase in MEP amplitude even though the voluntary electromyographic activity has not yet appeared. This 'excitable' period indicates the activation of motor cortex before the motor command is delivered. Application of this technique to the analysis of prolonged reaction time (akinesia) in patients with Parkinson's disease shows that the excitable period is prolonged. This describes the mechanism underlying the difficulty in the generation of a motor command in these patients.

  20. Functional organization of motor cortex of adult macaque monkeys is altered by sensory loss in infancy.

    PubMed

    Qi, Hui-Xin; Jain, Neeraj; Collins, Christine E; Lyon, David C; Kaas, Jon H

    2010-02-16

    When somatosensory cortex (S1) is deprived of some of its inputs after section of ascending afferents in the dorsal columns of the spinal cord, it reorganizes to overrepresent the surviving inputs. As somatosensory cortex provides guiding sensory information to motor cortex, such sensory loss and representational reorganization could affect the development of the motor map in primary motor cortex (M1), especially if the sensory loss occurs early in development. To address this possibility, the dorsal columns of the spinal cord were sectioned between cervical levels (C3-5) 3-12 days after birth in five macaque monkeys. After 3-5 years of maturation (young adults), we determined how movements were represented in M1 contralateral to the lesion by using microelectrodes to electrically stimulate sites in M1 to evoke movements. Although the details of the motor maps in these five monkeys varied, the forelimb motor maps were abnormal. The representations of digit movements were reduced and abnormally arranged. Current levels for evoking movements from the forelimb region of M1 were in the normal range, but the lowest mean stimulation thresholds were for wrist or elbow instead of digit movements. Incomplete lesions and bilateral lesions produced fewer abnormalities. The results suggest that the development of normal motor cortex maps in M1 depends on sensory feedback from somatosensory maps.

  1. Task-dependent engagements of the primary visual cortex during kinesthetic and visual motor imagery.

    PubMed

    Mizuguchi, Nobuaki; Nakamura, Maiko; Kanosue, Kazuyuki

    2017-01-01

    Motor imagery can be divided into kinesthetic and visual aspects. In the present study, we investigated excitability in the corticospinal tract and primary visual cortex (V1) during kinesthetic and visual motor imagery. To accomplish this, we measured motor evoked potentials (MEPs) and probability of phosphene occurrence during the two types of motor imageries of finger tapping. The MEPs and phosphenes were induced by transcranial magnetic stimulation to the primary motor cortex and V1, respectively. The amplitudes of MEPs and probability of phosphene occurrence during motor imagery were normalized based on the values obtained at rest. Corticospinal excitability increased during both kinesthetic and visual motor imagery, while excitability in V1 was increased only during visual motor imagery. These results imply that modulation of cortical excitability during kinesthetic and visual motor imagery is task dependent. The present finding aids in the understanding of the neural mechanisms underlying motor imagery and provides useful information for the use of motor imagery in rehabilitation or motor imagery training.

  2. The Neural Mechanism Exploration of Adaptive Motor Control: Dynamical Economic Cell Allocation in the Primary Motor Cortex.

    PubMed

    Li, Wei; Guo, Yangyang; Fan, Jing; Ma, Chaolin; Ma, Xuan; Chen, Xi; He, Jiping

    2016-06-14

    Adaptive flexibility is of significance for the smooth and efficient movements in goal attainment. However, the underlying work mechanism of the cerebral cortex in adaptive motor control still remains unclear. How does the cerebral cortex organize and coordinate the activity of a large population of cells in the implementation of various motor strategies? To explore this issue, single-unit activities from the M1 region and kinematic data were recorded simultaneously in monkeys performing 3D reach-to-grasp tasks with different perturbations. Varying motor control strategies were employed and achieved in different perturbed tasks, via the dynamic allocation of cells to modulate specific movement parameters. An economic principle was proposed for the first time to describe a basic rule for cell allocation in the primary motor cortex. This principle, defined as the Dynamic Economic Cell Allocation Mechanism (DECAM), guarantees benefit maximization in cell allocation under limited neuronal resources, and avoids committing resources to uneconomic investments for unreliable factors with no or little revenue. That is to say, the cells recruited are always preferentially allocated to those factors with reliable return; otherwise, the cells are dispatched to respond to other factors about task. The findings of this study might partially reveal the working mechanisms underlying the role of the cerebral cortex in adaptive motor control, wherein is also of significance for the design of future intelligent brain-machine interfaces and rehabilitation device.

  3. The Role of Dopamine in Normal Rodent Motor Cortex: Physiological Effects and Structural Correlates

    DTIC Science & Technology

    1999-04-05

    differs somewhat in that the tract lies dorsally in the cervical spinal regions (Paxinos and Watson, 1986 ), and it is unlikely that any axons... 1986 ; Salamone et aI., 1990) and diminished accuracy and rate of skilled movements (Sabol et aI., 1985; Whishawat aI., 1986 ). These motor deficits...pathway has been implicated in their modulation (Whishaw et aI., 1986 ). However, the motor cortex is involved in some of these same aspects of motor

  4. Visuo-motor integration and control in the human posterior parietal cortex: evidence from TMS and fMRI.

    PubMed

    Iacoboni, Marco

    2006-01-01

    The posterior parietal cortex is a fundamental structure for visuo-motor integration and control. Here I discuss recent transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) studies that I interpret as suggesting four concepts. The evolutionary process has enlarged the human posterior parietal cortex while still preserving the internal structure of the posterior parietal cortex of other primates. Visuo-motor control in the posterior parietal cortex may be implemented by coding primarily action goals. The lateralization of visuo-motor functions in the posterior parietal cortex suggests that the left posterior parietal cortex is more concerned with tool use and the right posterior parietal cortex is more concerned with imitation of the actions of others. Finally, visuo-motor inter-hemispheric transfer through parietal callosal fibers occurs at the level of 'motor intention'.

  5. The microstructural border between the motor and the cognitive domain in the human cerebral cortex.

    PubMed

    Geyer, S

    2004-01-01

    When we voluntarily interact with our environment, the agranular frontal cortex (Brodmann's areas 4 and 6) plays a pivotal role in cortical motor control. The primary motor cortex (area 4) influences kinematic and dynamic parameters of movements, whereas the rostrally adjoining nonprimary motor cortex (area 6) uses external (e.g., sensory) or internal cues to trigger and guide movements. Once thought to be homogeneous, data from nonhuman primates have shown that area 6 is a mosaic of areas, each with distinct structural and functional properties: the supplementary motor areas "SMA proper" and "pre-SMA" on the mesial cortical surface, and the dorso- and ventrolateral premotor cortex on the cortical convexity. Dorso- and ventrolateral premotor areas are specifically connected with posterior parietal areas. These parieto-frontal circuits work in parallel and tranform different aspects of sensory information into appropriate motor commands. The rostral border of area 6 is very important for functional neuroimaging studies in humans since it separates the "motor domain" of the supplementary motor/premotor cortex from the "cognitive domain" of the prefrontal cortex. Can the topography of this border be inferred from the gyral pattern of the frontal lobe? To answer this, ten postmorterm brains were scanned with a T1-weighted magnetic resonance sequence. The brains were serially sectioned at 20 micro M and area 6 was defined by subjective and objective cytoarchitectonic analysis. Each brain's histological volume (with the representation of area 6) was reconstructed in 3-D and spatially normalized to the reference brain of a computerized atlas. The ten normalized volumes were superimposed and a population map was generated that describes, for each voxel, how many brains have a representation of area 6. On the mesial coetical surface, the rostral border of area 6 lies rostral to the anterior commissure-- though the distance varies across different brains. On the lateral

  6. Analysis on bilateral hindlimb mapping in motor cortex of the rat by an intracortical microstimulation method.

    PubMed

    Seong, Han Yu; Cho, Ji Young; Choi, Byeong Sam; Min, Joong Kee; Kim, Yong Hwan; Roh, Sung Woo; Kim, Jeong Hoon; Jeon, Sang Ryong

    2014-04-01

    Intracortical microstimulation (ICMS) is a technique that was developed to derive movement representation of the motor cortex. Although rats are now commonly used in motor mapping studies, the precise characteristics of rat motor map, including symmetry and consistency across animals, and the possibility of repeated stimulation have not yet been established. We performed bilateral hindlimb mapping of motor cortex in six Sprague-Dawley rats using ICMS. ICMS was applied to the left and the right cerebral hemisphere at 0.3 mm intervals vertically and horizontally from the bregma, and any movement of the hindlimbs was noted. The majority (80%± 11%) of responses were not restricted to a single joint, which occurred simultaneously at two or three hindlimb joints. The size and shape of hindlimb motor cortex was variable among rats, but existed on the convex side of the cerebral hemisphere in all rats. The results did not show symmetry according to specific joints in each rats. Conclusively, the hindlimb representation in the rat motor cortex was conveniently mapped using ICMS, but the characteristics and inter-individual variability suggest that precise individual mapping is needed to clarify motor distribution in rats.

  7. Contribution of the premotor cortex to consolidation of motor sequence learning in humans during sleep.

    PubMed

    Nitsche, Michael A; Jakoubkova, Michaela; Thirugnanasambandam, Nivethida; Schmalfuss, Leonie; Hullemann, Sandra; Sonka, Karel; Paulus, Walter; Trenkwalder, Claudia; Happe, Svenja

    2010-11-01

    Motor learning and memory consolidation require the contribution of different cortices. For motor sequence learning, the primary motor cortex is involved primarily in its acquisition. Premotor areas might be important for consolidation. In accordance, modulation of cortical excitability via transcranial DC stimulation (tDCS) during learning affects performance when applied to the primary motor cortex, but not premotor cortex. We aimed to explore whether premotor tDCS influences task performance during motor memory consolidation. The impact of excitability-enhancing, -diminishing, or placebo premotor tDCS during rapid eye movement (REM) sleep on recall in the serial reaction time task (SRTT) was explored in healthy humans. The motor task was learned in the evening. Recall was performed immediately after tDCS or the following morning. In two separate control experiments, excitability-enhancing premotor tDCS was performed 4 h after task learning during daytime or immediately before conduction of a simple reaction time task. Excitability-enhancing tDCS performed during REM sleep increased recall of the learned movement sequences, when tested immediately after stimulation. REM density was enhanced by excitability-increasing tDCS and reduced by inhibitory tDCS, but did not correlate with task performance. In the control experiments, tDCS did not improve performance. We conclude that the premotor cortex is involved in motor memory consolidation during REM sleep.

  8. Inhibitory and Excitatory Motor Cortex Dysfunction Persists in the Chronic Post-Stroke Recovery Phase

    PubMed Central

    Malcolm, M.P.; Vaughn, H.N.; Greene, D.

    2014-01-01

    Purpose Establish differences in intracortical facilitation (ICF) and inhibition (ICI) between survivors of stroke and healthy individuals. Methods Fourteen chronic stroke survivors and 19 healthy subjects were investigated using single and paired-pulse transcranial magnetic stimulation (TMS). TMS was applied over the motor cortex in thelesioned (stroke survivors) or left (healthy subjects) hemisphere. Motor evoked potentials (MEPs) were collected from the contra lateral first dorsal interosseus. Subjects received 40 pseudo-randomized trials consisting of 10 trials for each: conditioning stimulus, test stimulus (TS), ICF, and ICI. Between the groups, we compared MEP amplitudes for TS, ICF, and ICI, motor threshold (MT), and ICF/ICI ratio. Results Compared to healthy individuals, the stroke group exhibited higher MT and lower ICI; the difference ICF neared significance. The ICF/ICI ratio was significantly lower in the stroke group and close to 1, indicating little difference between ICF and ICI responses. These differences demonstrate that motor cortex excitatory and inhibitory mechanisms are impaired for individuals in the chronic post-stroke recovery phase. Conclusions Compared to healthy individuals, both global and intracortical TMS measures reveal reduced motor cortex excitability in survivors of stroke. Interventions that normalize motor cortex excitability may promote better neurophysiological conditions for motor recovery to occur. PMID:25350636

  9. Motor, cognitive, and affective areas of the cerebral cortex influence the adrenal medulla

    PubMed Central

    Dum, Richard P.; Levinthal, David J.; Strick, Peter L.

    2016-01-01

    Modern medicine has generally viewed the concept of “psychosomatic” disease with suspicion. This view arose partly because no neural networks were known for the mind, conceptually associated with the cerebral cortex, to influence autonomic and endocrine systems that control internal organs. Here, we used transneuronal transport of rabies virus to identify the areas of the primate cerebral cortex that communicate through multisynaptic connections with a major sympathetic effector, the adrenal medulla. We demonstrate that two broad networks in the cerebral cortex have access to the adrenal medulla. The larger network includes all of the cortical motor areas in the frontal lobe and portions of somatosensory cortex. A major component of this network originates from the supplementary motor area and the cingulate motor areas on the medial wall of the hemisphere. These cortical areas are involved in all aspects of skeletomotor control from response selection to motor preparation and movement execution. The second, smaller network originates in regions of medial prefrontal cortex, including a major contribution from pregenual and subgenual regions of anterior cingulate cortex. These cortical areas are involved in higher-order aspects of cognition and affect. These results indicate that specific multisynaptic circuits exist to link movement, cognition, and affect to the function of the adrenal medulla. This circuitry may mediate the effects of internal states like chronic stress and depression on organ function and, thus, provide a concrete neural substrate for some psychosomatic illness. PMID:27528671

  10. Microinjections of tubocurarine, leptazol, strychnine and picrotoxin into the cerebral cortex of anaesthetized cats

    PubMed Central

    Banerjee, U.; Feldberg, W.; Georgiev, V. P.

    1970-01-01

    1. In cats anaesthetized with intravenous chloralose, microinjections of tubocurarine, leptazol, strychnine or picrotoxin, in a volume of 1 μl, were made into the grey matter of the cerebral cortex and the electrical activity was recorded from the site of injection with the microinjection cannula which, insulated except at its tip, served as recording electrode. 2. Routinely the injections were made into the gyrus splenialis or into the underlying gyrus cinguli close to the mid-line, because the injections would then most likely be in grey and not in white matter. Injected in this way all four drugs set up foci of excitation which gave rise to synchronous firing of a large number of neurones with the result that high voltage negative spikes were recorded from the microinjection cannula. 3. On injection into the gyrus splenialis the threshold dose was about 0·04 μg for picrotoxin, about 0·2 μg for tubocurarine, about 5 μg for strychnine and 25 to 50 μg for leptazol. Following the injection of larger doses the spike discharge continued for a few hours after picrotoxin and tubocurarine, for over an hour after strychnine, but for a few minutes only after leptazol. On injection into the gyrus cinguli the threshold doses were slightly greater and with larger doses the spikes occurred at greater frequency but were of lower voltage than in the gyrus splenialis. 4. With large doses of picrotoxin injected into the gyrus splenialis the spikes developed an after-positivity and an after-discharge which sometimes passed into a short period of fast activity. 5. The foci of excitation set up by the drugs were restricted to the site of injection because on raising or lowering the microinjection cannula the spikes recorded from it quickly decreased in voltage and then disappeared. When the injections were made close to a sulcus and the microinjection cannula, on being lowered, traversed the sulcus, the spikes changed their polarity. 6. The spike discharge appears to be a

  11. Rapid Dynamics of Contrast Responses in the Cat Primary Visual Cortex

    PubMed Central

    Hu, Ming; Wang, Yong; Wang, Yi

    2011-01-01

    The visual information we receive during natural vision changes rapidly and continuously. The visual system must adapt to the spatiotemporal contents of the environment in order to efficiently process the dynamic signals. However, neuronal responses to luminance contrast are usually measured using drifting or stationary gratings presented for a prolonged duration. Since motion in our visual field is continuous, the signals received by the visual system contain an abundance of transient components in the contrast domain. Here using a modified reverse correlation method, we studied the properties of responses of neurons in the cat primary visual cortex to different contrasts of grating stimuli presented statically and transiently for 40 ms, and showed that neurons can effectively discriminate the rapidly changing contrasts. The change in the contrast response function (CRF) over time mainly consisted of an increment in contrast gain (CRF shifts to left) in the developing phase of temporal responses and a decrement in response gain (CRF shifts downward) in the decay phase. When the distribution range of stimulus contrasts was increased, neurons demonstrated decrement in contrast gain and response gain. Our results suggest that contrast gain control (contrast adaptation) and response gain control mechanisms are well established during the first tens of milliseconds after stimulus onset and may cooperatively mediate the rapid dynamic responses of visual cortical neurons to the continuously changing contrast. This fast contrast adaptation may play a role in detecting contrast contours in the context of visual scenes that are varying rapidly. PMID:21998655

  12. Spectrotemporal Processing in Spectral Tuning Modules of Cat Primary Auditory Cortex

    PubMed Central

    Atencio, Craig A.; Schreiner, Christoph E.

    2012-01-01

    Spectral integration properties show topographical order in cat primary auditory cortex (AI). Along the iso-frequency domain, regions with predominantly narrowly tuned (NT) neurons are segregated from regions with more broadly tuned (BT) neurons, forming distinct processing modules. Despite their prominent spatial segregation, spectrotemporal processing has not been compared for these regions. We identified these NT and BT regions with broad-band ripple stimuli and characterized processing differences between them using both spectrotemporal receptive fields (STRFs) and nonlinear stimulus/firing rate transformations. The durations of STRF excitatory and inhibitory subfields were shorter and the best temporal modulation frequencies were higher for BT neurons than for NT neurons. For NT neurons, the bandwidth of excitatory and inhibitory subfields was matched, whereas for BT neurons it was not. Phase locking and feature selectivity were higher for NT neurons. Properties of the nonlinearities showed only slight differences across the bandwidth modules. These results indicate fundamental differences in spectrotemporal preferences - and thus distinct physiological functions - for neurons in BT and NT spectral integration modules. However, some global processing aspects, such as spectrotemporal interactions and nonlinear input/output behavior, appear to be similar for both neuronal subgroups. The findings suggest that spectral integration modules in AI differ in what specific stimulus aspects are processed, but they are similar in the manner in which stimulus information is processed. PMID:22384036

  13. L-dopa methyl ester attenuates amblyopia-induced neuronal injury in visual cortex of amblyopic cat.

    PubMed

    Li, Rong; Liang, Tao; Chen, Zhaoni; Zhang, Shijun; Lin, Xing; Huang, Renbin

    2013-09-15

    In the present study, we aimed to assess the potential anti-amblyopic effects of L-dopa methyl ester (LDME) on visual cortex area 17 in an amblyopic feline model induced by monocular vision deprivation. After LDME administration, pathophysiologic and ultrastructural observations were utilized to examine the morphological changes of nerve cells in visual cortex area 17. Dopamine (DA) and its metabolite contents in visual cortex area 17 were investigated through HPLC analysis. Apoptotic cells in visual cortex area 17 were evaluated by TUNEL assay. Additionally, the c-fos expression both at gene and protein levels was assessed using RT-PCR and immunohistochemistry analyses, respectively. The contents of DA and its metabolites were elevated in visual cortex area 17. Neuronal rejuvenation which occurred in visual cortex area 17 was observed through anatomical and physiological assessments. Similarly, TUNEL results showed that neuronal apoptosis was inhibited in the visual cortex of amblyopic cats by both L-dopa and LDME therapies. Meanwhile, the c-fos expression was notably up-regulated at both the mRNA and protein levels by the treatments. These findings suggested that LDME treatment could effectively increase DA and its metabolite contents, and restrain the apoptotic process, as well as elevate the c-fos expression in nerve cells of visual cortex area 17. Taken together, LDME might ameliorate the functional cytoarchitecture in visual cortex area 17 through mechanisms that elevate DA content and increase endogenous c-fos expression, as well as inhibit neuronal lesion in visual cortex tissue.

  14. Differential grey matter changes in sensorimotor cortex related to exceptional fine motor skills.

    PubMed

    Stoeckel, M Cornelia; Morgenroth, Farina; Buetefisch, Cathrin M; Seitz, Rüdiger J

    2012-01-01

    Functional changes in sensorimotor representation occur in response to use and lesion throughout life. Emerging evidence suggests that functional changes are paralleled by respective macroscopic structural changes. In the present study we used voxel-based morphometry to investigate sensorimotor cortex in subjects with congenitally malformed upper extremities. We expected increased or decreased grey matter to parallel the enlarged or reduced functional representations we reported previously. More specifically, we expected decreased grey matter values in lateral sensorimotor cortex related to compromised hand function and increased grey matter values in medial sensorimotor cortex due to compensatory foot use. We found a medial cluster of grey matter increase in subjects with frequent, hand-like compensatory foot use. This increase was predominantly seen for lateral premotor, supplementary motor, and motor areas and only marginally involved somatosensory cortex. Contrary to our expectation, subjects with a reduced number of fingers, who had shown shrinkage of the functional hand representation previously, did not show decreased grey matter values within lateral sensorimotor cortex. Our data suggest that functional plastic changes in sensorimotor cortex can be associated with increases in grey matter but may also occur in otherwise macroscopically normal appearing grey matter volumes. Furthermore, macroscopic structural changes in motor and premotor areas may be observed without respective changes in somatosensory cortex.

  15. Motor cortex stimulation for central and peripheral deafferentation pain. Report of eight cases.

    PubMed

    Saitoh, Y; Shibata, M; Hirano, S; Hirata, M; Mashimo, T; Yoshimine, T

    2000-01-01

    The authors tested a modified motor cortex stimulation protocol for treatment of central and peripheral types of deafferentation pain. Four patients with thalamic pain and four with peripheral deafferentation pain were studied. Preoperative pharmacological tests of pain relief were performed using phentolamine, lidocaine, ketamine, thiopental, and placebo. In five patients we placed a 20- or 40-electrode grid in the subdural space to determine the best stimulation point for pain relief for a few weeks before definitive placement of a four-electrode array. In three patients, the four-electrode array was implanted in the interhemispheric fissure as a one-stage procedure to treat lower-extremity pain. In two patients with pain extending from the extremity to the trunk or hip, dual devices were implanted to drive two electrodes. Six of eight patients experienced pain reduction (two each with excellent, good, and fair relief) from motor cortex stimulation. No correlation was apparent between pharmacological test results and the effectiveness of motor cortex stimulation. Patients with peripheral deafferentation pain, including two with phantom-limb pain and two with brachial plexus injury, attained pain relief from motor cortex stimulation, with excellent results in two cases. Testing performed with a subdural multiple-electrode grid was helpful in locating the best stimulation point for pain relief. Motor cortex stimulation may be effective for treating peripheral as well as central deafferentation pain.

  16. Sexual motivation is reflected by stimulus-dependent motor cortex excitability.

    PubMed

    Schecklmann, Martin; Engelhardt, Kristina; Konzok, Julian; Rupprecht, Rainer; Greenlee, Mark W; Mokros, Andreas; Langguth, Berthold; Poeppl, Timm B

    2015-08-01

    Sexual behavior involves motivational processes. Findings from both animal models and neuroimaging in humans suggest that the recruitment of neural motor networks is an integral part of the sexual response. However, no study so far has directly linked sexual motivation to physiologically measurable changes in cerebral motor systems in humans. Using transcranial magnetic stimulation in hetero- and homosexual men, we here show that sexual motivation modulates cortical excitability. More specifically, our results demonstrate that visual sexual stimuli corresponding with one's sexual orientation, compared with non-corresponding visual sexual stimuli, increase the excitability of the motor cortex. The reflection of sexual motivation in motor cortex excitability provides evidence for motor preparation processes in sexual behavior in humans. Moreover, such interrelationship links theoretical models and previous neuroimaging findings of sexual behavior.

  17. The effects of motor cortex rTMS on corticospinal descending activity.

    PubMed

    Di Lazzaro, V; Profice, P; Pilato, F; Dileone, M; Oliviero, A; Ziemann, U

    2010-04-01

    Repetitive transcranial magnetic stimulation (rTMS) of the human motor cortex can produce long-lasting changes in the excitability of the motor cortex to single pulse transcranial magnetic stimulation (TMS). rTMS may increase or decrease motor cortical excitability depending critically on the characteristics of the stimulation protocol. However, it is still poorly defined which mechanisms and central motor circuits contribute to these rTMS induced long-lasting excitability changes. We have had the opportunity to perform a series of direct recordings of the corticospinal volley evoked by single pulse TMS from the epidural space of conscious patients with chronically implanted spinal electrodes before and after several protocols of rTMS that increase or decrease brain excitability. These recordings provided insight into the physiological basis of the effects of rTMS and the specific motor cortical circuits involved.

  18. Peripheral Nerve Injury in Developing Rats Reorganizes Motor Cortex.

    DTIC Science & Technology

    1986-05-19

    Island 02912 *r201-484 It. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Personnel and Training Research Program May 19, 1986 Office of Naval...The Cerebral Cortex The Functional Areas of the Cerebral Cortex, E. G. Jones and A. Peters. Eds. (Plenum, New York, 1986 ) vol. 5, p. 243-270. 12. In rat...and processed for Nissl substance or cytochrome oxidase staining. In reconstructions, nap borders were defined as the mid-point between two distinct

  19. Differential Modification of Cortical and Thalamic Projections to Cat Primary Auditory Cortex Following Early- and Late-Onset Deafness.

    PubMed

    Chabot, Nicole; Butler, Blake E; Lomber, Stephen G

    2015-10-15

    Following sensory deprivation, primary somatosensory and visual cortices undergo crossmodal plasticity, which subserves the remaining modalities. However, controversy remains regarding the neuroplastic potential of primary auditory cortex (A1). To examine this, we identified cortical and thalamic projections to A1 in hearing cats and those with early- and late-onset deafness. Following early deafness, inputs from second auditory cortex (A2) are amplified, whereas the number originating in the dorsal zone (DZ) decreases. In addition, inputs from the dorsal medial geniculate nucleus (dMGN) increase, whereas those from the ventral division (vMGN) are reduced. In late-deaf cats, projections from the anterior auditory field (AAF) are amplified, whereas those from the DZ decrease. Additionally, in a subset of early- and late-deaf cats, area 17 and the lateral posterior nucleus (LP) of the visual thalamus project concurrently to A1. These results demonstrate that patterns of projections to A1 are modified following deafness, with statistically significant changes occurring within the auditory thalamus and some cortical areas. Moreover, we provide anatomical evidence for small-scale crossmodal changes in projections to A1 that differ between early- and late-onset deaf animals, suggesting that potential crossmodal activation of primary auditory cortex differs depending on the age of deafness onset.

  20. Action Verbs and the Primary Motor Cortex: A Comparative TMS Study of Silent Reading, Frequency Judgments, and Motor Imagery

    ERIC Educational Resources Information Center

    Tomasino, Barbara; Fink, Gereon R.; Sparing, Roland; Dafotakis, Manuel; Weiss, Peter H.

    2008-01-01

    Single pulse transcranial magnetic stimulation (TMS) was applied to the hand area of the left primary motor cortex or, as a control, to the vertex (STIMULATION: TMS[subscript M1] vs. TMS[subscript vertex]) while right-handed volunteers silently read verbs related to hand actions. We examined three different tasks and time points for stimulation…

  1. tDCS-induced alterations in GABA concentration within primary motor cortex predict motor learning and motor memory: a 7 T magnetic resonance spectroscopy study.

    PubMed

    Kim, Soyoung; Stephenson, Mary C; Morris, Peter G; Jackson, Stephen R

    2014-10-01

    Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that alters cortical excitability in a polarity specific manner and has been shown to influence learning and memory. tDCS may have both on-line and after-effects on learning and memory, and the latter are thought to be based upon tDCS-induced alterations in neurochemistry and synaptic function. We used ultra-high-field (7 T) magnetic resonance spectroscopy (MRS), together with a robotic force adaptation and de-adaptation task, to investigate whether tDCS-induced alterations in GABA and Glutamate within motor cortex predict motor learning and memory. Note that adaptation to a robot-induced force field has long been considered to be a form of model-based learning that is closely associated with the computation and 'supervised' learning of internal 'forward' models within the cerebellum. Importantly, previous studies have shown that on-line tDCS to the cerebellum, but not to motor cortex, enhances model-based motor learning. Here we demonstrate that anodal tDCS delivered to the hand area of the left primary motor cortex induces a significant reduction in GABA concentration. This effect was specific to GABA, localised to the left motor cortex, and was polarity specific insofar as it was not observed following either cathodal or sham stimulation. Importantly, we show that the magnitude of tDCS-induced alterations in GABA concentration within motor cortex predicts individual differences in both motor learning and motor memory on the robotic force adaptation and de-adaptation task.

  2. Effects of citalopram on the excitability of the human motor cortex: a paired magnetic stimulation study.

    PubMed

    Robol, Elisa; Fiaschi, Antonio; Manganotti, Paolo

    2004-06-15

    Several recent reports suggest the possibility of monitoring pharmacological effects on brain excitability through transcranial magnetic stimulation (TMS). Different drugs have been studied using paired magnetic stimulation in normal subjects and patients. In particular, it has been suggested that antidepressant drugs may have an appreciable effect on motor excitability. The aim of the present study was to investigate motor area excitability in normal subjects after oral administration of a single dose of citalopram, a selective serotonin reuptake inhibitor (SSRI) antidepressant. Motor cortex excitability was studied by single and paired transcranial magnetic stimulation before and 2.5 and 36 (t1/2=36 h) h after oral administration of 30 mg of citalopram. Cortical excitability was measured using different transcranial magnetic stimulation parameters: motor threshold (MT), motor-evoked potential (MEP) amplitude and latency, motor recruitment, duration of cortical silent period (CSP), intracortical inhibition and intracortical facilitation. Spinal excitability and peripheral nerve conduction were measured by F response and M wave. Temporary but significant increases in motor threshold, motor-evoked potentials, silent period and intracortical inhibition were observed 2.5 h after drug administration, without any significant changes in motor-evoked potential amplitude and latency and spinal excitability parameters. Our findings suggest that a single oral dose of citalopram can induce significant but transitory suppression of motor cortex excitability in normal subjects.

  3. Dynamic Re-wiring of Neural Circuits in the Motor Cortex in Mouse Models of Parkinson's Disease

    PubMed Central

    Lalchandani, Rupa R.; Cui, Yuting; Shu, Yu; Xu, Tonghui; Ding, Jun B.

    2015-01-01

    SUMMARY Dynamic adaptations in synaptic plasticity are critical for learning new motor skills and maintaining memory throughout life, which rapidly decline with Parkinson's disease (PD). Plasticity in the motor cortex is important for acquisition and maintenance of novel motor skills, but how the loss of dopamine in PD leads to disrupted structural and functional plasticity in the motor cortex is not well understood. Here, we utilized mouse models of PD and 2-photon imaging to show that dopamine depletion resulted in structural changes in the motor cortex. We further discovered that dopamine D1 and D2 receptor signaling were linked to selectively and distinctly regulating these aberrant changes in structural and functional plasticity. Our findings suggest that both D1 and D2 receptor signaling regulate motor cortex plasticity, and loss of dopamine results in atypical synaptic adaptations that may contribute to the impairment of motor performance and motor memory observed in PD. PMID:26237365

  4. Motor imagery in REM sleep is increased by transcranial direct current stimulation of the left motor cortex (C3).

    PubMed

    Speth, Jana; Speth, Clemens

    2016-06-01

    This study investigates if anodal transcranial direct current stimulation (tDCS) of areas above the motor cortex (C3) influences the quantity and quality of spontaneous motor imagery experienced in REM sleep. A randomized triple-blinded design was used, combining neurophysiological techniques with a tool of quantitative mentation report analysis developed from cognitive linguistics and generative grammar. The results indicate that more motor imagery, and more athletic motor imagery, is induced by anodal tDCS in comparison to cathodal and sham tDCS. This insight may have implications beyond basic consciousness research. Motor imagery in REM sleep has been hypothesized to serve the rehearsal of motor movements, which benefits later motor performance. Electrophysiological manipulations of motor imagery in REM sleep could in the long run be used for rehabilitative tDCS protocols benefitting temporarily immobile clinical patients, especially those who cannot perform specific motor imagery tasks - such as dementia patients, infants with developmental and motor disorders, and coma patients.

  5. [Participation of the primary motor cortex in programming of muscle activity during catching of falling object].

    PubMed

    Kazennikov, O V; Lipshits, M I

    2011-01-01

    Object fell into the cup that sitting subject held between thumb and index fingers. Transcranial magnetic stimulation (TMS) of the primary motor cortex was performed early before and during anticipatory grip force increasing. Comparison of current EMG activity of adductor pollicis brevis and first dorsal interosseous muscles and responses of these muscles on TMS showed that responses were increased before the raising of muscle activity. From the other side only slight augmentation of responses was observed during subsequent strong muscle activation. It is assumed that the increasing of the TMS responses that occurred before the initiation of muscle activity reflects the enhancement ofthe motor cortex excitability associated to specific processes related to the motor cortex participation in programming of the muscles activities.

  6. Combinatorial Motor Training Results in Functional Reorganization of Remaining Motor Cortex after Controlled Cortical Impact in Rats.

    PubMed

    Combs, Hannah L; Jones, Theresa A; Kozlowski, Dorothy A; Adkins, DeAnna L

    2016-04-15

    Cortical reorganization subsequent to post-stroke motor rehabilitative training (RT) has been extensively examined in animal models and humans. However, similar studies focused on the effects of motor training after traumatic brain injury (TBI) are lacking. We previously reported that after a moderate/severe TBI in adult male rats, functional improvements in forelimb use were accomplished only with a combination of skilled forelimb reach training and aerobic exercise, with or without nonimpaired forelimb constraint. Thus, the current study was designed to examine the relationship between functional motor cortical map reorganization after experimental TBI and the behavioral improvements resulting from this combinatorial rehabilitative regime. Adult male rats were trained to proficiency on a skilled reaching task, received a unilateral controlled cortical impact (CCI) over the forelimb area of the caudal motor cortex (CMC). Three days post-CCI, animals began RT (n = 13) or no rehabilitative training (NoRT) control procedures (n = 13). The RT group participated in daily skilled reach training, voluntary aerobic exercise, and nonimpaired forelimb constraint. This RT regimen significantly improved impaired forelimb reaching success and normalized reaching strategies, consistent with previous findings. RT also enlarged the area of motor cortical wrist representation, derived by intracortical microstimulation, compared to NoRT. These findings indicate that sufficient RT can greatly improve motor function and improve the functional integrity of remaining motor cortex after a moderate/severe CCI. When compared with findings from stroke models, these findings also suggest that more intense RT may be needed to improve motor function and remodel the injured cortex after TBI.

  7. Motor Cortex Plasticity during Unilateral Finger Movement with Mirror Visual Feedback

    PubMed Central

    Kumru, Hatice; Albu, Sergiu; Pelayo, Raul; Rothwell, John; Opisso, Eloy; Leon, Daniel; Soler, Dolor; Tormos, Josep Maria

    2016-01-01

    Plasticity is one of the most important physiological mechanisms underlying motor recovery from brain lesions. Rehabilitation methods, such as mirror visual feedback therapy, which are based on multisensory integration of motor, cognitive, and perceptual processes, are considered effective methods to induce cortical reorganization. The present study investigated 3 different types of visual feedback (direct, mirrored, and blocked visual feedback: DVF, MVF, and BVF, resp.) on M1 cortex excitability and intracortical inhibition/facilitation at rest and during phasic unimanual motor task in 11 healthy individuals. The excitability of the ipsilateral M1 cortex and the intracortical facilitation increased during motor task performance in the DVF and MVF but not in the BVF condition. In addition, MVF induced cortical disinhibition of the ipsilateral hemisphere to the index finger performing the motor task, which was greater when compared to the BVF and restricted to the homologue first dorsal interosseous muscle. The visual feedback is relevant to M1 cortex excitability modulation but the MVF plays a crucial role in promoting changes in intracortical inhibition in comparison to BVF. Altogether, it can be concluded that a combination of motor training with MVF therapy may induce more robust neuroplastic changes through multisensory integration that is relevant to motor rehabilitation. PMID:26881121

  8. Motor Cortex Plasticity during Unilateral Finger Movement with Mirror Visual Feedback.

    PubMed

    Kumru, Hatice; Albu, Sergiu; Pelayo, Raul; Rothwell, John; Opisso, Eloy; Leon, Daniel; Soler, Dolor; Tormos, Josep Maria

    2016-01-01

    Plasticity is one of the most important physiological mechanisms underlying motor recovery from brain lesions. Rehabilitation methods, such as mirror visual feedback therapy, which are based on multisensory integration of motor, cognitive, and perceptual processes, are considered effective methods to induce cortical reorganization. The present study investigated 3 different types of visual feedback (direct, mirrored, and blocked visual feedback: DVF, MVF, and BVF, resp.) on M1 cortex excitability and intracortical inhibition/facilitation at rest and during phasic unimanual motor task in 11 healthy individuals. The excitability of the ipsilateral M1 cortex and the intracortical facilitation increased during motor task performance in the DVF and MVF but not in the BVF condition. In addition, MVF induced cortical disinhibition of the ipsilateral hemisphere to the index finger performing the motor task, which was greater when compared to the BVF and restricted to the homologue first dorsal interosseous muscle. The visual feedback is relevant to M1 cortex excitability modulation but the MVF plays a crucial role in promoting changes in intracortical inhibition in comparison to BVF. Altogether, it can be concluded that a combination of motor training with MVF therapy may induce more robust neuroplastic changes through multisensory integration that is relevant to motor rehabilitation.

  9. Motor cortex plasticity induced by paired associative stimulation is enhanced in physically active individuals.

    PubMed

    Cirillo, John; Lavender, Andrew P; Ridding, Michael C; Semmler, John G

    2009-12-15

    Recent evidence indicates that regular physical activity enhances brain plasticity (i.e. the ability to reorganise neural connections) and improves neurocognitive function. However, the effect of regular physical activity on human motor cortex function is unknown. The purpose of this study was to examine motor cortex plasticity for a small hand muscle in highly active and sedentary individuals. Electromyographic recordings were obtained from the left abductor pollicis brevis (APB) muscle of 14 active and 14 sedentary subjects (aged 18-38 yrs). The extent of physical activity was assessed by questionnaire, where the physically active subjects performed >150 min per day moderate-to-vigorous aerobic activity on at least 5 days per week, whereas the sedentary group performed <20 min per day of physical activity on no more than 3 days per week. Transcranial magnetic stimulation (TMS) of the right hemisphere was used to assess changes in APB motor-evoked potentials (MEPs), input-output curve (IO curve), short-interval intracortical inhibition (SICI) and cortical silent period (CSP). Neuroplastic changes were induced using paired-associative stimulation (PAS), which consisted of 90 paired stimuli (0.05 Hz for 30 min) of median nerve electrical stimulation at the wrist followed 25 ms later by TMS to the hand area of motor cortex. The IO curve slope was 35% steeper in individuals with increased physical activity (combined before and after PAS, P < 0.05), suggesting increased motor cortex excitability, although there was no difference in SICI or CSP between groups. PAS induced an increase in MEP amplitude in the physically active subjects (54% increase compared with before, P < 0.01), but no significant facilitation in the sedentary subjects. We conclude that participation in regular physical activity may offer global benefits to motor cortex function that enhances neuroplasticity, which could improve motor learning and neurorehabilitation in physically active individuals.

  10. Excitatory inputs to spiny cells in layers 4 and 6 of cat striate cortex.

    PubMed Central

    Bannister, N J; Nelson, J C; Jack, J J B

    2002-01-01

    The principal target of lateral geniculate nucleus in the cat visual cortex is the stellate neurons of layer 4. In previously reported work with intracellular recording and extracellular stimulation in slices of visual cortex, three general classes of fast excitatory synaptic potentials (EPSPs) in layer 4a spiny stellate neurons were identified. One of these classes, characterized by large and relatively invariant amplitudes (mean 1.7 mV, average coefficient of variation (CV) 0.083) were attributed to the action of geniculate axons because, unlike the other two classes, they could not be matched by intracortical inputs, using paired recording. We have examined in detail the properties of this synaptic input in twelve examples, selecting for study those EPSPs where there was secure extracellular stimulation of the single fibre input to a pair of stimuli 50 ms apart. In our analysis, we conclude that the depression that these inputs show to the second stimulus is entirely postsynaptic, since the evidence strongly suggests that the probability of transmitter release at the synaptic site(s) remains 1.0 for both stimuli. We argue that the most plausible explanation for this postsynaptic depression is a reduction in the average probability of opening the synaptic channels. Using a simple biochemical analysis (c.f. Sigworth plot), it is then possible to calculate the number of synaptic channels and their probability of opening, for each of the 12 connections. The EPSPs had a mean amplitude of 1.91 mV (+/- 1.3 mV SD) and a mean CV of 0.067 (+/- 0.022). The calculated number of channels ranged from 20 to 158 (59.4 +/- 48.7) and their probability of opening to the first EPSP had an average of 0.83 (+/- 0.09), with an average depression of the probability to 0.60 for the second EPSP. Geniculate afferents also terminate in layer 6. Intracellular recordings were also made in the upper part of this layer and a total of 51 EPSPs were recorded from pyramidal cells of three

  11. Motor demand-dependent improvement in accuracy following low-frequency transcranial magnetic stimulation of left motor cortex

    PubMed Central

    Hines, Benjamin; Shuster, Linda; Pergami, Paola; Mathes, Adam

    2011-01-01

    The role of primary motor cortex (M1) in the control of voluntary movements is still unclear. In brain functional imaging studies of unilateral hand performance, bilateral M1 activation is inconsistently observed, and disruptions of M1 using repetitive transcranial magnetic stimulation (rTMS) lead to variable results in the hand motor performance. As the motor tasks differed qualitatively in these studies, it is conceivable that M1 contribution differs depending on the level of skillfulness. The objective of the present study was to determine whether M1 contribution to hand motor performance differed depending on the level of precision of the motor task. Here, we used low-frequency rTMS of left M1 to determine its effect on the performance of a pointing task that allows the parametric increase of the level of precision and thereby increase the level of required precision quantitatively. We found that low-frequency rTMS improved performance in both hands for the task with the highest demand on precision, whereas performance remained unchanged for the tasks with lower demands. These results suggest that the functional relevance of M1 activity for motor performance changes as a function of motor demand. The bilateral effect of rTMS to left M1 would also support the notion of M1 functions at a higher level in motor control by integrating afferent input from nonprimary motor areas. PMID:21734109

  12. Modulation of motor cortex excitability by physical similarity with an observed hand action.

    PubMed

    Désy, Marie-Christine; Théoret, Hugo

    2007-10-03

    The passive observation of hand actions is associated with increased motor cortex excitability, presumably reflecting activity within the human mirror neuron system (MNS). Recent data show that in-group ethnic membership increases motor cortex excitability during observation of culturally relevant hand gestures, suggesting that physical similarity with an observed body part may modulate MNS responses. Here, we ask whether the MNS is preferentially activated by passive observation of hand actions that are similar or dissimilar to self in terms of sex and skin color. Transcranial magnetic stimulation-induced motor evoked potentials were recorded from the first dorsal interosseus muscle while participants viewed videos depicting index finger movements made by female or male participants with black or white skin color. Forty-eight participants equally distributed in terms of sex and skin color participated in the study. Results show an interaction between self-attributes and physical attributes of the observed hand in the right motor cortex of female participants, where corticospinal excitability is increased during observation of hand actions in a different skin color than that of the observer. Our data show that specific physical properties of an observed action modulate motor cortex excitability and we hypothesize that in-group/out-group membership and self-related processes underlie these effects.

  13. Embryonic amygdalar transplants in adult rats with motor cortex lesions: a molecular and electrophysiological analysis.

    PubMed

    Jiménez-Díaz, Lydia; Nava-Mesa, Mauricio O; Heredia, Margarita; Riolobos, Adelaida S; Gómez-Álvarez, Marcelo; Criado, José María; de la Fuente, Antonio; Yajeya, Javier; Navarro-López, Juan D

    2011-01-01

    Transplants of embryonic nervous tissue ameliorate motor deficits induced by motor cortex lesions in adult animals. Restoration of lost brain functions has been recently shown in grafts of homotopic cortical origin, to be associated with a functional integration of the transplant after development of reciprocal host-graft connections. Nevertheless little is known about physiological properties or gene expression profiles of cortical implants with functional restorative capacity but no cortical origin. In this study, we show molecular and electrophysiological evidence supporting the functional development and integration of heterotopic transplants of embryonic amygdalar tissue placed into pre-lesioned motor cortex of adult rats. Grafts were analyzed 3 months post-transplantation. Using reverse transcriptase quantitative polymerase chain reaction, we found that key glutamatergic, GABAergic, and muscarinic receptors transcripts were expressed at different quantitative levels both in grafted and host tissues, but were all continuously present in the graft. Parallel sharp electrode recordings of grafted neurons in brain slices showed a regular firing pattern of transplanted neurons similar to host amygdalar pyramidal neurons. Synaptic connections from the adjacent host cortex on grafted neurons were electrophysiologically investigated and confirmed our molecular results. Taken together, our findings indicate that grafted neurons from a non-cortical, non-motor-related, but ontogenetical similar source, not only received functionally effective contacts from the adjacent motor cortex, but also developed electrophysiological and gene expression patterns comparable to host pyramidal neurons; suggesting an interesting tool for the field of neural repair and donor tissue in adults.

  14. Plasticity in adult cat visual cortex (area 17) following circumscribed monocular lesions of all retinal layers

    PubMed Central

    Calford, M B; Wang, C; Taglianetti, V; Waleszczyk, W J; Burke, W; Dreher, B

    2000-01-01

    In eight adult cats intense, sharply circumscribed, monocular laser lesions were used to remove all cellular layers of the retina. The extents of the retinal lesions were subsequently confirmed with counts of α-ganglion cells in retinal whole mounts; in some cases these revealed radial segmental degeneration of ganglion cells distal to the lesion.Two to 24 weeks later, area 17 (striate cortex; V1) was studied electrophysiologically in a standard anaesthetized, paralysed (artificially respired) preparation. Recording single- or multineurone activity revealed extensive topographical reorganization within the lesion projection zone (LPZ).Thus, with stimulation of the lesioned eye, about 75 % of single neurones in the LPZ had ‘ectopic’ visual discharge fields which were displaced to normal retina in the immediate vicinity of the lesion.The sizes of the ectopic discharge fields were not significantly different from the sizes of the normal discharge fields. Furthermore, binocular cells recorded from the LPZ, when stimulated via their ectopic receptive fields, exhibited orientation tuning and preferred stimulus velocities which were indistinguishable from those found when the cells were stimulated via the normal eye.However, the responses to stimuli presented via ectopic discharge fields were generally weaker (lower peak discharge rates) than those to presentations via normal discharge fields, and were characterized by a lower-than-normal upper velocity limit.Overall, the properties of the ectopic receptive fields indicate that cortical mechanisms rather than a retinal ‘periphery’ effect underlie the topographic reorganization of area 17 following monocular retinal lesions. PMID:10767137

  15. Current direction specificity of continuous θ-burst stimulation in modulating human motor cortex excitability when applied to somatosensory cortex.

    PubMed

    Jacobs, Mark F; Zapallow, Christopher M; Tsang, Philemon; Lee, Kevin G H; Asmussen, Michael J; Nelson, Aimee J

    2012-11-14

    The present study examines the influence of primary somatosensory cortex (SI) on corticospinal excitability within primary motor cortex (M1) using repetitive transcranial magnetic stimulation. Two groups of subjects participated and both received continuous theta-burst stimulation (cTBS) over SI. One group received cTBS oriented to induce anterior-to-posterior (AP) followed by posterior-to-anterior (PA) current flow in the cortex and the other group received cTBS in the opposite direction (PA-AP). Motor evoked potentials (MEPs) were measured from the first dorsal interosseous muscle of the left and right hand before and at three time points (5, 25, 45 min) following cTBS over left-hemisphere SI. CTBS over SI in the AP-PA direction increased contralateral MEPs at 5 and 45 min with a near significant increase at 25 min. In contrast, PA-AP cTBS decreased contralateral MEPs at 25 min. We conclude that cTBS over SI modulates neural output directed to the hand with effects that depend on the direction of induced current.

  16. Alumina cream-induced focal motor seizures in cats: bilateral lesions of the mesencephalic reticular formation.

    PubMed

    Velasco, M; Velasco, F; Cepeda, C; Márquez, I; Estrada-Villanueva, F

    1986-06-01

    The effect of bilateral lesions of the mesencephalic reticular formation on the EEG-EMG patterns of types B and C alumina cream-induced focal motor seizures was studied in cats with chronically implanted electrode and cannula lesion systems. EEG patterns included number, amplitude, and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included changes in muscular multiple-unit activity time locked to the onset of type B spikes and to the onset and end of type C tonic-clonic EEG paroxysmal discharges. The lesions persistently blocked the orienting response to visual, auditory, and tactile stimuli to both sides in all cats and produced other neurologic symptoms partially or totally recovered in some cats. The lesions significantly increased the number, amplitude, and contralateral propagation of type B EEG spikes and the occurrence, but not the duration, of type C EEG tonic-clonic discharges. Ipsi- and contralateral adversion of the tonic phase were completely blocked and the muscular contractions of the clonic phase were reduced and delayed. These facts suggest that in intact epileptic cats, the mesencephalic reticular formation has an ascending suppressive influence on the mechanism related to EEG spike generation and precipitation of seizures but also a descending facilitatory control on the corticospinal epileptic impulses mediated through pyramidal and extrapyramidal pathways.

  17. Summation of forces from multiple motor units in the cat soleus muscle.

    PubMed

    Perreault, Eric J; Day, Scott J; Hulliger, Manuel; Heckman, C J; Sandercock, Thomas G

    2003-02-01

    Nearly all muscle models and most motor control concepts assume that forces from individual muscle fibers and motor units sum in an additive manner once effects of in-series tendon compliance are taken into account. Due to the numerous mechanical linkages between individual fibers, though, it is unclear whether this assumption is warranted. This work examined motor unit force summation over a wide range of muscle forces in the cat soleus. Nonadditive summation implies a nonlinear summation of motor unit forces. Summation nonlinearities were quantified during interactions of 10 individual motor units and 4 motor unit bundles containing approximately 10 units each. These protocols allowed motor unit force summation to be examined from approximately 0 to 25% of tetanic muscle force. Nonlinear summation was assessed by comparing the actual forces to the algebraic sum of individual units and bundles stimulated in isolation. Superadditive summation meant that the actual force exceeded the algebraic sum, whereas subadditive summation meant that the actual force was smaller than the algebraic sum. Experiments tested the hypothesis that superadditive summation occurs at low force levels when few motor units are recruited, whereas subadditive summation prevails above 10% of tetanic force. Results were consistent with this hypothesis. As in previous studies, nonlinear summation in the soleus was modest, but a clear transition from predominately superadditive to predominantly subadditive summation occurred in the range of 6-8% of tetanic force. The largest nonlinearities were transient and appeared at the onset of recruitment and derecruitment of groups of motor units. The results are discussed in terms of the mechanical properties of the connective tissue forming the tendon and linking muscle fibers.

  18. Behavioral modulation of neural encoding of click-trains in the primary and nonprimary auditory cortex of cats.

    PubMed

    Dong, Chao; Qin, Ling; Zhao, Zhenling; Zhong, Renjia; Sato, Yu

    2013-08-07

    Neural representation of acoustic stimuli in the mammal auditory cortex (AC) has been extensively studied using anesthetized or awake nonbehaving animals. Recently, several studies have shown that active engagement in an auditory behavioral task can substantially change the neuron response properties compared with when animals were passively listening to the same sounds; however, these studies mainly investigated the effect of behavioral state on the primary auditory cortex and the reported effects were inconsistent. Here, we examined the single-unit spike activities in both the primary and nonprimary areas along the dorsal-to-ventral direction of the cat's AC, when the cat was actively discriminating click-trains at different repetition rates and when it was passively listening to the same stimuli. We found that the changes due to task engagement were heterogeneous in the primary AC; some neurons showed significant increases in driven firing rate, others showed decreases. But in the nonprimary AC, task engagement predominantly enhanced the neural responses, resulting in a substantial improvement of the neural discriminability of click-trains. Additionally, our results revealed that neural responses synchronizing to click-trains gradually decreased along the dorsal-to-ventral direction of cat AC, while nonsynchronizing responses remained less changed. The present study provides new insights into the hierarchical organization of AC along the dorsal-to-ventral direction and highlights the importance of using behavioral animals to investigate the later stages of cortical processing.

  19. Fetal frontal cortex transplant (/sup 14/C) 2-deoxyglucose uptake and histology: survival in cavities of host rat brain motor cortex

    SciTech Connect

    Sharp, F.R.; Gonzalez, M.F.

    1984-10-01

    Fetal frontal neocortex from 18-day-old rat embryonic brain was transplanted into cavities in 30-day-old host motor cortex. Sixty days after transplantation, 5 of 15 transplanted rats had surviving fetal transplants. The fetal cortex transplants were physically attached to the host brain, completely filled the original cavity, and had numerous surviving cells including pyramidal neurons. Cell lamination within the fetal transplant was abnormal. The (/sup 14/C) 2-deoxyglucose uptake of all five of the fetal neocortex transplants was less than adjacent cortex and contralateral host motor-sensory cortex, but more than adjacent corpus callosum white matter. The results indicate that fetal frontal neocortex can be transplanted into damaged rat motor cortex. The metabolic rate of the transplants suggests they could be partially functional.

  20. Homeostatic modulation of stimulation-dependent plasticity in human motor cortex.

    PubMed

    Ilić, N V; Milanović, S; Krstić, J; Bajec, D D; Grajić, M; Ilić, T V

    2011-01-01

    Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N(20)) (PAS(LTP)), and at ISI of N(20) shortened for 5 msec (PAS(LTD)) - protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PAS(LTP) and PAS(LTD) were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PAS(LTP) MEP amplitudes were significantly decreased in case of PAS(LTP), while in the case of PAS(LTD) an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability.

  1. Interaction between visual and motor cortex: a transcranial magnetic stimulation study.

    PubMed

    Strigaro, Gionata; Ruge, Diane; Chen, Jui-Cheng; Marshall, Louise; Desikan, Mahalekshmi; Cantello, Roberto; Rothwell, John C

    2015-05-15

    The major link between the visual and motor systems is via the dorsal stream pathways from visual to parietal and frontal areas of the cortex. Although the pathway appears to be indirect, there is evidence that visual input can reach the motor cortex at relatively short latency. To shed some light on its neural basis, we studied the visuomotor interaction using paired transcranial magnetic stimulation (TMS). Motor-evoked potentials (MEPs) were recorded from the right first dorsal interosseous in sixteen healthy volunteers. A conditioning stimulus (CS) was applied over the phosphene hotspot of the visual cortex, followed by a test stimulus over the left primary motor cortex (M1) with a random interstimulus interval (ISI) in range 12-40 ms. The effects of paired stimulation were retested during visual and auditory reaction-time tasks (RT). Finally, we measured the effects of a CS on short-interval intracortical inhibition (SICI). At rest, a CS over the occiput significantly (P < 0.001) suppressed test MEPs with an ISI in the range 18-40 ms. In the visual RT, inhibition with an ISI of 40 ms (but not 18 ms) was replaced by a time-specific facilitation (P < 0.001), whereas, in the auditory RT, the CS no longer had any effect on MEPs. Finally, an occipital CS facilitated SICI with an ISI of 40 ms (P < 0.01). We conclude that it is possible to study separate functional connections from visual to motor cortices using paired-TMS with an ISI in the range 18-40 ms. The connections are inhibitory at rest and possibly mediated by inhibitory interneurones in the motor cortex. The effect with an ISI of 40 ms reverses into facilitation during a visuomotor RT but not an audiomotor RT. This suggests that it plays a role in visuomotor integration.

  2. Modulation of excitability in human primary somatosensory and motor cortex by paired associative stimulation targeting the primary somatosensory cortex.

    PubMed

    Kriváneková, Lucia; Lu, Ming-Kuei; Bliem, Barbara; Ziemann, Ulf

    2011-10-01

    Input from primary somatosensory cortex (S1) to primary motor cortex (M1) is important for high-level motor performance, motor skill learning and motor recovery after brain lesion. This study tested the effects of manipulating S1 excitability with paired associative transcranial stimulation (S1-PAS) on M1 excitability. Given the important role of S1 in sensorimotor integration, we hypothesized that changes in S1 excitability would be directly paralleled by changes in M1 excitability. We applied two established protocols (S1-PAS(LTP) and S1-PAS(LTD) ) to the left S1 to induce long-term potentiation (LTP)-like or long-term depression (LTD)-like plasticity. S1 excitability was assessed by the early cortical components (N20-P25) of the median nerve somatosensory-evoked potential. M1 excitability was assessed by motor-evoked potential amplitude and short-interval intracortical inhibition. Effects of S1-PAS(LTP) were compared with those of a PAS(LTP) protocol targeting the left M1 (M1-PAS(LTP) ). S1-PAS(LTP) and S1-PAS(LTD) did not result in significant modifications of S1 or M1 excitability at the group level due to substantial interindividual variability. The individual S1-PAS-induced changes in S1 and M1 excitability showed no correlation. Furthermore, the individual changes in S1 and M1 excitability induced by S1-PAS(LTP) did not correlate with changes in M1 excitability induced by M1-PAS(LTP) . This demonstrates that the effects of S1-PAS in S1 are variable across individuals and, within a given individual, unrelated to those induced by S1-PAS or M1-PAS in M1. Potentially, this extends the opportunities of therapeutic PAS applications because M1-PAS 'non-responders' may well respond to S1-PAS.

  3. Neural Representation and Causal Models in Motor Cortex.

    PubMed

    Chaisanguanthum, Kris S; Shen, Helen H; Sabes, Philip N

    2017-03-22

    Dorsal premotor (PMd) and primary motor (M1) cortices play a central role in mapping sensation to movement. Many studies of these areas have focused on correlation-based tuning curves relating neural activity to task or movement parameters, but the link between tuning and movement generation is unclear. We recorded motor preparatory activity from populations of neurons in PMd/M1 as macaque monkeys performed a visually guided reaching task and show that tuning curves for sensory inputs (reach target direction) and motor outputs (initial movement direction) are not typically aligned. We then used a simple, causal model to determine the expected relationship between sensory and motor tuning. The model shows that movement variability is minimized when output neurons (those that directly drive movement) have target and movement tuning that are linearly related across targets and cells. In contrast, for neurons that only affect movement via projections to output neurons, the relationship between target and movement tuning is determined by the pattern of projections to output neurons and may even be uncorrelated, as was observed for the PMd/M1 population as a whole. We therefore determined the relationship between target and movement tuning for subpopulations of cells defined by the temporal duration of their spike waveforms, which may distinguish cell types. We found a strong correlation between target and movement tuning for only a subpopulation of neurons with intermediate spike durations (trough-to-peak ∼350 μs after high-pass filtering), suggesting that these cells have the most direct role in driving motor output.SIGNIFICANCE STATEMENT This study focuses on how macaque premotor and primary motor cortices transform sensory inputs into motor outputs. We develop empirical and theoretical links between causal models of this transformation and more traditional, correlation-based "tuning curve" analyses. Contrary to common assumptions, we show that sensory and motor

  4. Differential effects of dual and unihemispheric motor cortex stimulation in older adults.

    PubMed

    Lindenberg, Robert; Nachtigall, Laura; Meinzer, Marcus; Sieg, Mira Maria; Flöel, Agnes

    2013-05-22

    Bihemispheric transcranial direct current stimulation (tDCS) is thought to upregulate excitability of the primary motor cortex (M1) using anodal stimulation while concurrently downregulating contralateral M1 using cathodal stimulation. This "dual" tDCS method enhances motor learning in healthy subjects and facilitates motor recovery after stroke. However, its impact on motor system activity and connectivity remains unknown. Therefore, we assessed neural correlates of dual and unihemispheric anodal tDCS effects in 20 healthy older subjects in a randomized, sham-controlled study using a cross-over design. Participants underwent tDCS and simultaneous functional magnetic resonance imaging during a choice reaction time task and at rest. Diffusion tensor imaging (DTI) allowed us to relate potential functional changes to structural parameters. The resting-state analysis demonstrated that, compared with sham, both dual and anodal tDCS decreased connectivity of right hippocampus and M1 (contralateral to the anode position) while increasing connectivity in the left prefrontal cortex. Notably, dual but not anodal tDCS enhanced connectivity of the left dorsal posterior cingulate cortex. Furthermore, dual tDCS yielded stronger activations in bilateral M1 compared with anodal tDCS when participants used either their left or right hand during the motor task. The corresponding tDCS-induced changes in laterality of activations were related to the microstructural status of transcallosal motor fibers. In conclusion, our results suggest that the impact of bihemispheric tDCS cannot be explained by mere add-on effects of anodal and concurrent cathodal stimulation, but rather by complex network modulations involving interhemispheric interactions and areas associated with motor control in the dorsal posterior cingulate cortex.

  5. Surgical Resection of Non-Glial Tumors in the Motor Cortex

    PubMed Central

    Lee, Seong-Jong; Im, Soo Bin; Kim, Bum-Tae

    2016-01-01

    Background Direct surgery to resect tumors in the motor cortex could improve neurological symptoms or cause novel motor weakness. The present study describes the neurological outcomes of patients after the surgical resection of non-glial tumors in the primary motor cortex. Methods The present study included 25 patients who had pathologically confirmed non-glial tumors in the motor cortex for which they underwent surgery. Tumor location was verified using anatomical landmarks on preoperative magnetic resonance imaging scans. All surgeries involved a craniotomy and tumor resection, especially use of the sulcal dissecting approach for intra-axial tumors. Results Of the 25 patients, 10 exhibited metastasis, 13 had a meningioma, and 2 had a cavernous malformation. Motor weakness and seizures were the most common symptoms, while 3 patients experienced only a headache. The tumor size was less than 20 mm in 4 patients, 20–40 mm in 14, and greater than 40 mm in seven. Of the 25 patients, 13 exhibited motor weakness prior to the operation, but most of these symptoms (76.9%) improved following surgery. On the other hand, eight patients experienced seizures prior to the surgery, and in three of these patients (37.5%), the seizures were not controlled after the surgery. In terms of surgical complications, a postoperative hematoma developed in one of the meningioma patients, and the patient's hemiparesis was aggravated. Conclusion The present findings show that careful and meticulous resection of non-glial tumors in the motor cortex can improve preoperative neurological signs, but it cannot completely control seizure activity. PMID:27867915

  6. How electrode montage affects transcranial direct current stimulation of the human motor cortex.

    PubMed

    Salvador, Ricardo; Wenger, Cornelia; Nitsche, Michael A; Miranda, Pedro C

    2015-01-01

    Several different electrode configurations were originally proposed to induce excitability changes in the hand area of the motor cortex in transcranial direct current stimulation (tDCS). However only one was found to efficiently affect cortical excitability: anode/cathode over the primary motor cortex and return electrode placed over the contralateral orbit (M-CF configuration). In this work we used the finite element method to calculate the electric field (E-field) induced in a realistic human head model in all the proposed electrode configurations. In order to analyze the results, average values of the E-field's magnitude and polar/azimuthal angles were calculated in several cortical motor and premotor areas which may have an effect on the output of the primary motor cortex. The average E-field's magnitude at the hand-knob (HK) was similar between the M-CF configuration (0.16 V/m) and a few other tested configurations, the same happening for the average polar angle (129°). However this configuration achieved the highest mean E-field values over premotor (PM) areas (0.21 V/m). These results show that the polar angle and the average magnitude of the E-field evaluated at the HK and at the PM cortex might be important parameters in predicting the success of a specific electrode montage in tDCS.

  7. The Somatotopy of Speech: Phonation and Articulation in the Human Motor Cortex

    ERIC Educational Resources Information Center

    Brown, Steven; Laird, Angela R.; Pfordresher, Peter Q.; Thelen, Sarah M.; Turkeltaub, Peter; Liotti, Mario

    2009-01-01

    A sizable literature on the neuroimaging of speech production has reliably shown activations in the orofacial region of the primary motor cortex. These activations have invariably been interpreted as reflecting "mouth" functioning and thus articulation. We used functional magnetic resonance imaging to compare an overt speech task with tongue…

  8. Frontal and motor cortex contributions to response inhibition: evidence from electrocorticography

    PubMed Central

    Fonken, Yvonne M.; Rieger, Jochem W.; Tzvi, Elinor; Crone, Nathan E.; Chang, Edward; Parvizi, Josef; Knight, Robert T.

    2016-01-01

    Changes in the environment require rapid modification or inhibition of ongoing behavior. We used the stop-signal paradigm and intracranial recordings to investigate response preparation, inhibition, and monitoring of task-relevant information. Electrocorticographic data were recorded in eight patients with electrodes covering frontal, temporal, and parietal cortex, and time-frequency analysis was used to examine power differences in the beta (13–30 Hz) and high-gamma bands (60–180 Hz). Over motor cortex, beta power decreased, and high-gamma power increased during motor preparation for both go trials (Go) and unsuccessful stops (US). For successful stops (SS), beta increased, and high-gamma was reduced, indexing the cancellation of the prepared response. In the middle frontal gyrus (MFG), stop signals elicited a transient high-gamma increase. The MFG response occurred before the estimated stop-signal reaction time but did not distinguish between SS and US trials, likely signaling attention to the salient stop stimulus. A postresponse high-gamma increase in MFG was stronger for US compared with SS and absent in Go, supporting a role in behavior monitoring. These results provide evidence for differential contributions of frontal subregions to response inhibition, including motor preparation and inhibitory control in motor cortex and cognitive control and action evaluation in lateral prefrontal cortex. PMID:26864760

  9. Frontal and motor cortex contributions to response inhibition: evidence from electrocorticography.

    PubMed

    Fonken, Yvonne M; Rieger, Jochem W; Tzvi, Elinor; Crone, Nathan E; Chang, Edward; Parvizi, Josef; Knight, Robert T; Krämer, Ulrike M

    2016-04-01

    Changes in the environment require rapid modification or inhibition of ongoing behavior. We used the stop-signal paradigm and intracranial recordings to investigate response preparation, inhibition, and monitoring of task-relevant information. Electrocorticographic data were recorded in eight patients with electrodes covering frontal, temporal, and parietal cortex, and time-frequency analysis was used to examine power differences in the beta (13-30 Hz) and high-gamma bands (60-180 Hz). Over motor cortex, beta power decreased, and high-gamma power increased during motor preparation for both go trials (Go) and unsuccessful stops (US). For successful stops (SS), beta increased, and high-gamma was reduced, indexing the cancellation of the prepared response. In the middle frontal gyrus (MFG), stop signals elicited a transient high-gamma increase. The MFG response occurred before the estimated stop-signal reaction time but did not distinguish between SS and US trials, likely signaling attention to the salient stop stimulus. A postresponse high-gamma increase in MFG was stronger for US compared with SS and absent in Go, supporting a role in behavior monitoring. These results provide evidence for differential contributions of frontal subregions to response inhibition, including motor preparation and inhibitory control in motor cortex and cognitive control and action evaluation in lateral prefrontal cortex.

  10. Poor Tolerance of Motor Cortex rTMS in Chronic Migraine

    PubMed Central

    Teo, Wei-Peng; Kannan, Aravinda; Loh, Pei-Kee; Chew, Effie; Sharma, Vijay Kumar

    2014-01-01

    Background: Two small studies had evaluated the efficacy of rTMS in migraine. One tested high frequency rTMS over the dorsolateral prefrontal cortex while the other evaluated 1 Hz rTMS over the vertex. Aim: To test the feasibility of 10 Hz rTMS of motor cortex as an adjunctive therapy in patients with chronic migraine Materials and Methods: We randomized (2:1 ratio) chronic migraine patients on medical preventive treatment to receive either rTMS or sham therapy for 10 sessions. rTMS (80% resting motor threshold, 10Hz, 20 trains, 5 secs/train, inter-train interval 1 min, total 1000 stimuli/session) was applied over the right motor cortex. Result: Nine patients were randomized. Six received rTMS and three had sham therapy. Three patients in the rTMS arm withdrew from the study due to increased headache frequency and discomfort from the treatment. The remaining six cases (3 rTMS, 3 sham) completed the study. The study was prematurely stopped due to the significant worsening of headache from rTMS. No significant differences in outcome measures were found between real and sham rTMS. Conclusion: Although the study was terminated prematurely, the high dropout rate (50%) due to worsening headaches suggested that rTMS over the motor cortex is poorly tolerated in chronic migraine. PMID:25386478

  11. Multitarget Multiscale Simulation for Pharmacological Treatment of Dystonia in Motor Cortex

    PubMed Central

    Neymotin, Samuel A.; Dura-Bernal, Salvador; Lakatos, Peter; Sanger, Terence D.; Lytton, William W.

    2016-01-01

    A large number of physiomic pathologies can produce hyperexcitability in cortex. Depending on severity, cortical hyperexcitability may manifest clinically as a hyperkinetic movement disorder or as epilpesy. We focus here on dystonia, a movement disorder that produces involuntary muscle contractions and involves pathology in multiple brain areas including basal ganglia, thalamus, cerebellum, and sensory and motor cortices. Most research in dystonia has focused on basal ganglia, while much pharmacological treatment is provided directly at muscles to prevent contraction. Motor cortex is another potential target for therapy that exhibits pathological dynamics in dystonia, including heightened activity and altered beta oscillations. We developed a multiscale model of primary motor cortex, ranging from molecular, up to cellular, and network levels, containing 1715 compartmental model neurons with multiple ion channels and intracellular molecular dynamics. We wired the model based on electrophysiological data obtained from mouse motor cortex circuit mapping experiments. We used the model to reproduce patterns of heightened activity seen in dystonia by applying independent random variations in parameters to identify pathological parameter sets. These models demonstrated degeneracy, meaning that there were many ways of obtaining the pathological syndrome. There was no single parameter alteration which would consistently distinguish pathological from physiological dynamics. At higher dimensions in parameter space, we were able to use support vector machines to distinguish the two patterns in different regions of space and thereby trace multitarget routes from dystonic to physiological dynamics. These results suggest the use of in silico models for discovery of multitarget drug cocktails. PMID:27378922

  12. Motor cortex activation in Parkinson's disease: dissociation of electrocortical and peripheral measures of response generation.

    PubMed

    Praamstra, P; Plat, E M; Meyer, A S; Horstink, M W

    1999-09-01

    This study investigated characteristics of motor cortex activation and response generation in Parkinson's disease with measures of electrocortical activity (lateralized readiness potential [LRP]), electromyographic activity (EMG), and isometric force in a noise-compatibility task. When presented with stimuli consisting of incompatible target and distractor elements asking for responses of opposite hands, patients were less able than control subjects to suppress activation of the motor cortex controlling the wrong response hand. This was manifested in the pattern of reaction times and in an incorrect lateralization of the LRP. Onset latency and rise time of the LRP did not differ between patients and control subjects, but EMG and response force developed more slowly in patients. Moreover, in patients but not in control subjects, the rate of development of EMG and response force decreased as reaction time increased. We hypothesize that this dissociation between electrocortical activity and peripheral measures in Parkinson's disease is the result of changes in motor cortex function that alter the relation between signal-related and movement-related neural activity in the motor cortex. In the LRP, this altered balance may obscure an abnormal development of movement-related neural activity.

  13. Spontaneously Fluctuating Motor Cortex Excitability in Alternating Hemiplegia of Childhood: A Transcranial Magnetic Stimulation Study

    PubMed Central

    Stern, William M.; Desikan, Mahalekshmi; Hoad, Damon; Jaffer, Fatima; Strigaro, Gionata; Sander, Josemir W.; Rothwell, John C.; Sisodiya, Sanjay M.

    2016-01-01

    Background Alternating hemiplegia of childhood is a very rare and serious neurodevelopmental syndrome; its genetic basis has recently been established. Its characteristic features include typically-unprovoked episodes of hemiplegia and other transient or more persistent neurological abnormalities. Methods We used transcranial magnetic stimulation to assess the effect of the condition on motor cortex neurophysiology both during and between attacks of hemiplegia. Nine people with alternating hemiplegia of childhood were recruited; eight were successfully tested using transcranial magnetic stimulation to study motor cortex excitability, using single and paired pulse paradigms. For comparison, data from ten people with epilepsy but not alternating hemiplegia, and ten healthy controls, were used. Results One person with alternating hemiplegia tested during the onset of a hemiplegic attack showed progressively diminishing motor cortex excitability until no response could be evoked; a second person tested during a prolonged bilateral hemiplegic attack showed unusually low excitability. Three people tested between attacks showed asymptomatic variation in cortical excitability, not seen in controls. Paired pulse paradigms, which probe intracortical inhibitory and excitatory circuits, gave results similar to controls. Conclusions We report symptomatic and asymptomatic fluctuations in motor cortex excitability in people with alternating hemiplegia of childhood, not seen in controls. We propose that such fluctuations underlie hemiplegic attacks, and speculate that the asymptomatic fluctuation we detected may be useful as a biomarker for disease activity. PMID:26999520

  14. Representation of the Speech Effectors in the Human Motor Cortex: Somatotopy or Overlap?

    ERIC Educational Resources Information Center

    Takai, Osamu; Brown, Steven; Liotti, Mario

    2010-01-01

    Somatotopy within the orofacial region of the human motor cortex has been a central concept in interpreting the results of neuroimaging and transcranial magnetic stimulation studies of normal and disordered speech. Yet, somatotopy has been challenged by studies showing overlap among the effectors within the homunculus. In order to address this…

  15. Alterations of motor performance and brain cortex mitochondrial function during ethanol hangover.

    PubMed

    Bustamante, Juanita; Karadayian, Analia G; Lores-Arnaiz, Silvia; Cutrera, Rodolfo A

    2012-08-01

    Ethanol has been known to affect various behavioral parameters in experimental animals, even several hours after ethanol (EtOH) is absent from blood circulation, in the period known as hangover. The aim of this study was to assess the effects of acute ethanol hangover on motor performance in association with the brain cortex energetic metabolism. Evaluation of motor performance and brain cortex mitochondrial function during alcohol hangover was performed in mice 6 hours after a high ethanol dose (hangover onset). Animals were injected i.p. either with saline (control group) or with ethanol (3.8 g/kg BW) (hangover group). Ethanol hangover group showed a bad motor performance compared with control animals (p < .05). Oxygen uptake in brain cortex mitochondria from hangover animals showed a 34% decrease in the respiratory control rate as compared with the control group. Mitochondrial complex activities were decreased being the complex I-III the less affected by the hangover condition; complex II-III was markedly decreased by ethanol hangover showing 50% less activity than controls. Complex IV was 42% decreased as compared with control animals. Hydrogen peroxide production was 51% increased in brain cortex mitochondria from the hangover group, as compared with the control animals. Quantification of the mitochondrial transmembrane potential indicated that ethanol injected animals presented 17% less ability to maintain the polarized condition as compared with controls. These results indicate that a clear decrease in proton motive force occurs in brain cortex mitochondria during hangover conditions. We can conclude that a decreased motor performance observed in the hangover group of animals could be associated with brain cortex mitochondrial dysfunction and the resulting impairment of its energetic metabolism.

  16. No evidence of somatotopic place of articulation feature mapping in motor cortex during passive speech perception.

    PubMed

    Arsenault, Jessica S; Buchsbaum, Bradley R

    2016-08-01

    The motor theory of speech perception has experienced a recent revival due to a number of studies implicating the motor system during speech perception. In a key study, Pulvermüller et al. (2006) showed that premotor/motor cortex differentially responds to the passive auditory perception of lip and tongue speech sounds. However, no study has yet attempted to replicate this important finding from nearly a decade ago. The objective of the current study was to replicate the principal finding of Pulvermüller et al. (2006) and generalize it to a larger set of speech tokens while applying a more powerful statistical approach using multivariate pattern analysis (MVPA). Participants performed an articulatory localizer as well as a speech perception task where they passively listened to a set of eight syllables while undergoing fMRI. Both univariate and multivariate analyses failed to find evidence for somatotopic coding in motor or premotor cortex during speech perception. Positive evidence for the null hypothesis was further confirmed by Bayesian analyses. Results consistently show that while the lip and tongue areas of the motor cortex are sensitive to movements of the articulators, they do not appear to preferentially respond to labial and alveolar speech sounds during passive speech perception.

  17. The Functional Organization and Cortical Connections of Motor Cortex in Squirrels

    PubMed Central

    Cooke, Dylan F.; Padberg, Jeffrey; Zahner, Tony

    2012-01-01

    Despite extraordinary diversity in the rodent order, studies of motor cortex have been limited to only 2 species, rats and mice. Here, we examine the topographic organization of motor cortex in the Eastern gray squirrel (Sciurus carolinensis) and cortical connections of motor cortex in the California ground squirrel (Spermophilus beecheyi). We distinguish a primary motor area, M1, based on intracortical microstimulation (ICMS), myeloarchitecture, and patterns of connectivity. A sensorimotor area between M1 and the primary somatosensory area, S1, was also distinguished based on connections, functional organization, and myeloarchitecture. We term this field 3a based on similarities with area 3a in nonrodent mammals. Movements are evoked with ICMS in both M1 and 3a in a roughly somatotopic pattern. Connections of 3a and M1 are distinct and suggest the presence of a third far rostral field, termed “F,” possibly involved in motor processing based on its connections. We hypothesize that 3a is homologous to the dysgranular zone (DZ) in S1 of rats and mice. Our results demonstrate that squirrels have both similar and unique features of M1 organization compared with those described in rats and mice, and that changes in 3a/DZ borders appear to have occurred in both lineages. PMID:22021916

  18. Linear summation of outputs in a balanced network model of motor cortex.

    PubMed

    Capaday, Charles; van Vreeswijk, Carl

    2015-01-01

    Given the non-linearities of the neural circuitry's elements, we would expect cortical circuits to respond non-linearly when activated. Surprisingly, when two points in the motor cortex are activated simultaneously, the EMG responses are the linear sum of the responses evoked by each of the points activated separately. Additionally, the corticospinal transfer function is close to linear, implying that the synaptic interactions in motor cortex must be effectively linear. To account for this, here we develop a model of motor cortex composed of multiple interconnected points, each comprised of reciprocally connected excitatory and inhibitory neurons. We show how non-linearities in neuronal transfer functions are eschewed by strong synaptic interactions within each point. Consequently, the simultaneous activation of multiple points results in a linear summation of their respective outputs. We also consider the effects of reduction of inhibition at a cortical point when one or more surrounding points are active. The network response in this condition is linear over an approximately two- to three-fold decrease of inhibitory feedback strength. This result supports the idea that focal disinhibition allows linear coupling of motor cortical points to generate movement related muscle activation patterns; albeit with a limitation on gain control. The model also explains why neural activity does not spread as far out as the axonal connectivity allows, whilst also explaining why distant cortical points can be, nonetheless, functionally coupled by focal disinhibition. Finally, we discuss the advantages that linear interactions at the cortical level afford to motor command synthesis.

  19. Selective Suppression of Local Circuits during Movement Preparation in the Mouse Motor Cortex.

    PubMed

    Hasegawa, Masashi; Majima, Kei; Itokazu, Takahide; Maki, Takakuni; Albrecht, Urban-Raphael; Castner, Nora; Izumo, Mariko; Sohya, Kazuhiro; Sato, Tatsuo K; Kamitani, Yukiyasu; Sato, Takashi R

    2017-03-14

    Prepared movements are more efficient than those that are not prepared for. Although changes in cortical activity have been observed prior to a forthcoming action, the circuits involved in motor preparation remain unclear. Here, we use in vivo two-photon calcium imaging to uncover changes in the motor cortex during variable waiting periods prior to a forepaw reaching task in mice. Consistent with previous reports, we observed a subset of neurons with increased activity during the waiting period; however, these neurons did not account for the degree of preparation as defined by reaction time (RT). Instead, the suppression of activity of distinct neurons in the same cortical area better accounts for RT. This suppression of neural activity resulted in a distinct and reproducible pattern when mice were well prepared. Thus, the selective suppression of network activity in the motor cortex may be a key feature of prepared movements.

  20. [Quality of neuronal signal registered in the monkey motor cortex with chronically implanted multiple microwires].

    PubMed

    Bondar', I V; Vasil'eva, L N; Badakva, A M; Miller, N V; Zobova, L N; Roshchin, V Iu

    2014-01-01

    Disconnection of central and peripheral parts of motor system leads to severe forms of disability. However, current research of brain-computer interfaces will solve the problem of rehabilitation of patients with motor disorders in future. Chronic recordings of single-unit activity in specialized areas of cerebral cortex could provide appropriate control signal for effectors with multiple degrees of freedom. In present article we evaluated the quality of chronic single-unit recordings in the primary motor cortex of awake behaving monkeys obtained with bundles of multiple microwires. Action potentials of proper quality were recorded from single units during three months. In some cases up to 7 single units could be extracted on a channel. Recording quality stabilized after 40 days since electrodes were implanted. Ultimately, functionality of multiple electrodes bundle makes it highly usable and reliable instrument for obtaining of control neurophysiologic signal from populations of neurons for brain-computer interfaces.

  1. Subtotal lesions of the visual cortex impair discrimination of hidden figures by cats.

    PubMed

    Cornwell, P; Overman, W; Campbell, A

    1980-04-01

    Cats with partial or nearly total ablation of areas 17, 18, and 19 were assessed on the discrimination of hidden figures and other visually guided behaviors to determine whether such insults produce deficits like those that follow lateral striate lesions in monkeys. Cats with destruction limited to the representation of central vision (Group M) were impaired at discriminating patterns complicated by extraneous cues, but they were less impaired than cats with more complete lesions (Group MS). The deficit was not a general one in visual learning since animals in both Groups M and MS learned simple pattern discriminations as rapidly as controls. It is suggested that the loss of geniculocortical functions representing central vision produces similar deficits in cats and monkeys but that to have this effect in cats, damage must extend beyond area 17.

  2. Two transient potassium currents in layer V pyramidal neurones from cat sensorimotor cortex.

    PubMed Central

    Spain, W J; Schwindt, P C; Crill, W E

    1991-01-01

    1. Two transient outward currents were identified in large pyramidal neurones from layer V of cat sensorimotor cortex ('Betz cells') using an in vitro brain slice preparation and single-microelectrode voltage clamp. Properties of the currents deduced from voltage-clamp measurements were reflected in neuronal responses during constant current stimulation. 2. Both transient outward currents rose rapidly after a step depolarization, but their subsequent time course differed greatly. The fast-transient current decayed within 20 ms, while the slow-transient current took greater than 10 s to decay. Raised extracellular potassium reduced current amplitude. Both currents were present in cadmium-containing or calcium-free perfusate. 3. Tetraethylammonium had little effect on the slow-transient current at a concentration of 1 mM, but the fast-transient current was reduced by 60%. 4-Aminopyridine had little effect on the fast-transient current over the range 20 microM-2 mM, but these concentrations reduced the slow-transient current and altered its time course. 4. Both transient currents were evoked by depolarizations below action potential threshold. The fast-transient current was evoked by a 7 mV smaller depolarization than the slow-transient current, but its chord conductance increased less steeply with depolarization. 5. Voltage-dependent inactivation of the fast-transient was steeper than that of the slow-transient current (4 vs. 7 mV per e-fold change), and half-inactivation occurred at a less negative potential (-59 vs. -65 mV). The activation and inactivation characteristics of each current overlapped, however, implying the existence of a steady 'window current' extending over a range of approximately 14 mV beginning negative to action potential threshold. 6. The fast-transient current displayed a clear voltage dependence of both its activation and inactivation kinetics, whereas the slow-transient current did not. Recovery of either current from inactivation took

  3. Dopamine in Motor Cortex Is Necessary for Skill Learning and Synaptic Plasticity

    PubMed Central

    Molina-Luna, Katiuska; Pekanovic, Ana; Röhrich, Sebastian; Hertler, Benjamin; Schubring-Giese, Maximilian; Rioult-Pedotti, Mengia-Seraina; Luft, Andreas R.

    2009-01-01

    Preliminary evidence indicates that dopamine given by mouth facilitates the learning of motor skills and improves the recovery of movement after stroke. The mechanism of these phenomena is unknown. Here, we describe a mechanism by demonstrating in rat that dopaminergic terminals and receptors in primary motor cortex (M1) enable motor skill learning and enhance M1 synaptic plasticity. Elimination of dopaminergic terminals in M1 specifically impaired motor skill acquisition, which was restored upon DA substitution. Execution of a previously acquired skill was unaffected. Reversible blockade of M1 D1 and D2 receptors temporarily impaired skill acquisition but not execution, and reduced long-term potentiation (LTP) within M1, a form of synaptic plasticity critically involved in skill learning. These findings identify a behavioral and functional role of dopaminergic signaling in M1. DA in M1 optimizes the learning of a novel motor skill. PMID:19759902

  4. Speed of processing in the primary motor cortex: a continuous theta burst stimulation study.

    PubMed

    Lakhani, Bimal; Bolton, David A E; Miyasike-Dasilva, Veronica; Vette, Albert H; McIlroy, William E

    2014-03-15

    'Temporally urgent' reactions are extremely rapid, spatially precise movements that are evoked following discrete stimuli. The involvement of primary motor cortex (M1) and its relationship to stimulus intensity in such reactions is not well understood. Continuous theta burst stimulation (cTBS) suppresses focal regions of the cortex and can assess the involvement of motor cortex in speed of processing. The primary objective of this study was to explore the involvement of M1 in speed of processing with respect to stimulus intensity. Thirteen healthy young adults participated in this experiment. Behavioral testing consisted of a simple button press using the index finger following median nerve stimulation of the opposite limb, at either high or low stimulus intensity. Reaction time was measured by the onset of electromyographic activity from the first dorsal interosseous (FDI) muscle of each limb. Participants completed a 30 min bout of behavioral testing prior to, and 15 min following, the delivery of cTBS to the motor cortical representation of the right FDI. The effect of cTBS on motor cortex was measured by recording the average of 30 motor evoked potentials (MEPs) just prior to, and 5 min following, cTBS. Paired t-tests revealed that, of thirteen participants, five demonstrated a significant attenuation, three demonstrated a significant facilitation and five demonstrated no significant change in MEP amplitude following cTBS. Of the group that demonstrated attenuated MEPs, there was a biologically significant interaction between stimulus intensity and effect of cTBS on reaction time and amplitude of muscle activation. This study demonstrates the variability of potential outcomes associated with the use of cTBS and further study on the mechanisms that underscore the methodology is required. Importantly, changes in motor cortical excitability may be an important determinant of speed of processing following high intensity stimulation.

  5. Constructing Visual Perception of Body Movement with the Motor Cortex

    PubMed Central

    Orgs, Guido; Dovern, Anna; Hagura, Nobuhiro; Haggard, Patrick; Fink, Gereon R.; Weiss, Peter H.

    2016-01-01

    The human brain readily perceives fluent movement from static input. Using functional magnetic resonance imaging, we investigated brain mechanisms that mediate fluent apparent biological motion (ABM) perception from sequences of body postures. We presented body and nonbody stimuli varying in objective sequence duration and fluency of apparent movement. Three body postures were ordered to produce a fluent (ABC) or a nonfluent (ACB) apparent movement. This enabled us to identify brain areas involved in the perceptual reconstruction of body movement from identical lower-level static input. Participants judged the duration of a rectangle containing body/nonbody sequences, as an implicit measure of movement fluency. For body stimuli, fluent apparent motion sequences produced subjectively longer durations than nonfluent sequences of the same objective duration. This difference was reduced for nonbody stimuli. This body-specific bias in duration perception was associated with increased blood oxygen level-dependent responses in the primary (M1) and supplementary motor areas. Moreover, fluent ABM was associated with increased functional connectivity between M1/SMA and right fusiform body area. We show that perceptual reconstruction of fluent movement from static body postures does not merely enlist areas traditionally associated with visual body processing, but involves cooperative recruitment of motor areas, consistent with a “motor way of seeing”. PMID:26534907

  6. Constructing Visual Perception of Body Movement with the Motor Cortex.

    PubMed

    Orgs, Guido; Dovern, Anna; Hagura, Nobuhiro; Haggard, Patrick; Fink, Gereon R; Weiss, Peter H

    2016-01-01

    The human brain readily perceives fluent movement from static input. Using functional magnetic resonance imaging, we investigated brain mechanisms that mediate fluent apparent biological motion (ABM) perception from sequences of body postures. We presented body and nonbody stimuli varying in objective sequence duration and fluency of apparent movement. Three body postures were ordered to produce a fluent (ABC) or a nonfluent (ACB) apparent movement. This enabled us to identify brain areas involved in the perceptual reconstruction of body movement from identical lower-level static input. Participants judged the duration of a rectangle containing body/nonbody sequences, as an implicit measure of movement fluency. For body stimuli, fluent apparent motion sequences produced subjectively longer durations than nonfluent sequences of the same objective duration. This difference was reduced for nonbody stimuli. This body-specific bias in duration perception was associated with increased blood oxygen level-dependent responses in the primary (M1) and supplementary motor areas. Moreover, fluent ABM was associated with increased functional connectivity between M1/SMA and right fusiform body area. We show that perceptual reconstruction of fluent movement from static body postures does not merely enlist areas traditionally associated with visual body processing, but involves cooperative recruitment of motor areas, consistent with a "motor way of seeing".

  7. Influence of Motor Cortex Stimulation During Motor Training on Neuroplasticity as a Potential Therapeutic Intervention.

    PubMed

    Massie, Crystal L; White, Caylen; Pruit, Katie; Freel, Aubrey; Staley, Kaylin; Backes, Morgan

    2017-02-06

    Rehabilitation options to promote neuroplasticity may be enhanced when patients are engaged in motor practice during repetitive transcranial magnetic stimulation (rTMS). Twelve participants completed 3 separate sessions: motor practice, motor practice with rTMS, and rTMS only: motor practice consisted of 30 isometric contractions and subthreshold rTMS was 30, 3-s trains at 10 Hz. Assessments included the Box and Block Test (BBT), force steadiness (10% of the maximum voluntary contraction), and TMS (cortical excitability, intracortical inhibition, and intracortical facilitation). Participants significantly increased BBT scores following the combined condition. Force steadiness improved after all 3 conditions (p < .05). TMS outcomes depended on intervention condition with significant increases in facilitation following the motor practice plus rTMS condition. All interventions influenced motor control, yet are likely modulated differently when combining motor practice plus rTMS. These results help guide the clinical utility of rTMS as an intervention to influence motor control.

  8. Trunk robot rehabilitation training with active stepping reorganizes and enriches trunk motor cortex representations in spinal transected rats.

    PubMed

    Oza, Chintan S; Giszter, Simon F

    2015-05-06

    Trunk motor control is crucial for postural stability and propulsion after low thoracic spinal cord injury (SCI) in animals and humans. Robotic rehabilitation aimed at trunk shows promise in SCI animal models and patients. However, little is known about the effect of SCI and robot rehabilitation of trunk on cortical motor representations. We previously showed reorganization of trunk motor cortex after adult SCI. Non-stepping training also exacerbated some SCI-driven plastic changes. Here we examine effects of robot rehabilitation that promotes recovery of hindlimb weight support functions on trunk motor cortex representations. Adult rats spinal transected as neonates (NTX rats) at the T9/10 level significantly improve function with our robot rehabilitation paradigm, whereas treadmill-only trained do not. We used intracortical microstimulation to map motor cortex in two NTX groups: (1) treadmill trained (control group); and (2) robot-assisted treadmill trained (improved function group). We found significant robot rehabilitation-driven changes in motor cortex: (1) caudal trunk motor areas expanded; (2) trunk coactivation at cortex sites increased; (3) richness of trunk cortex motor representations, as examined by cumulative entropy and mutual information for different trunk representations, increased; (4) trunk motor representations in the cortex moved toward more normal topography; and (5) trunk and forelimb motor representations that SCI-driven plasticity and compensations had caused to overlap were segregated. We conclude that effective robot rehabilitation training induces significant reorganization of trunk motor cortex and partially reverses some plastic changes that may be adaptive in non-stepping paraplegia after SCI.

  9. Neuronal correlates of motor performance and motor learning in the primary motor cortex of monkeys adapting to an external force field.

    PubMed

    Li, C S; Padoa-Schioppa, C; Bizzi, E

    2001-05-01

    The primary motor cortex (M1) is known to control motor performance. Recent findings have also implicated M1 in motor learning, as neurons in this area show learning-related plasticity. In the present study, we analyzed the neuronal activity recorded in M1 in a force field adaptation task. Our goal was to investigate the neuronal reorganization across behavioral epochs (before, during, and after adaptation). Here we report two main findings. First, memory cells were present in two classes. With respect to the changes of preferred direction (Pd), these two classes complemented each other after readaptation. Second, for the entire neuronal population, the shift of Pd matched the shift observed for muscles. These results provide a framework whereby the activity of distinct neuronal subpopulations combines to subserve both functions of motor performance and motor learning.

  10. Neutralization of Nogo-A Enhances Synaptic Plasticity in the Rodent Motor Cortex and Improves Motor Learning in Vivo

    PubMed Central

    Weinmann, Oliver; Kellner, Yves; Yu, Xinzhu; Vicente, Raul; Gullo, Miriam; Kasper, Hansjörg; Lussi, Karin; Ristic, Zorica; Luft, Andreas R.; Rioult-Pedotti, Mengia; Zuo, Yi; Zagrebelsky, Marta; Schwab, Martin E.

    2014-01-01

    The membrane protein Nogo-A is known as an inhibitor of axonal outgrowth and regeneration in the CNS. However, its physiological functions in the normal adult CNS remain incompletely understood. Here, we investigated the role of Nogo-A in cortical synaptic plasticity and motor learning in the uninjured adult rodent motor cortex. Nogo-A and its receptor NgR1 are present at cortical synapses. Acute treatment of slices with function-blocking antibodies (Abs) against Nogo-A or against NgR1 increased long-term potentiation (LTP) induced by stimulation of layer 2/3 horizontal fibers. Furthermore, anti-Nogo-A Ab treatment increased LTP saturation levels, whereas long-term depression remained unchanged, thus leading to an enlarged synaptic modification range. In vivo, intrathecal application of Nogo-A-blocking Abs resulted in a higher dendritic spine density at cortical pyramidal neurons due to an increase in spine formation as revealed by in vivo two-photon microscopy. To investigate whether these changes in synaptic plasticity correlate with motor learning, we trained rats to learn a skilled forelimb-reaching task while receiving anti-Nogo-A Abs. Learning of this cortically controlled precision movement was improved upon anti-Nogo-A Ab treatment. Our results identify Nogo-A as an influential molecular modulator of synaptic plasticity and as a regulator for learning of skilled movements in the motor cortex. PMID:24966370

  11. Healthy and diseased corticospinal motor neurons are selectively transduced upon direct AAV2-2 injection into the motor cortex

    PubMed Central

    Jara, J H; Stanford, M J; Zhu, Y; Tu, M; Hauswirth, W W; Bohn, M C; DeVries, S H; Özdinler, P H

    2016-01-01

    Direct gene delivery to the neurons of interest, without affecting other neuron populations in the cerebral cortex, represent a challenge owing to the heterogeneity and cellular complexity of the brain. Genetic modulation of corticospinal motor neurons (CSMN) is required for developing effective and long-term treatment strategies for motor neuron diseases, in which voluntary movement is impaired. Adeno-associated viruses (AAV) have been widely used for neuronal transduction studies owing to long-term and stable gene expression as well as low immunoreactivity in humans. Here we report that AAV2-2 transduces CSMN with high efficiency upon direct cortex injection and that transduction efficiencies are similar during presymptomatic and symptomatic stages in hSOD1G93A transgenic amyotrophic lateral sclerosis (ALS) mice. Our findings reveal that choice of promoter improves selectivity as AAV2-2 chicken β-actin promoter injection results in about 70% CSMN transduction, the highest percentage reported to date. CSMN transduction in both wild-type and transgenic ALS mice allows detailed analysis of single axon fibers within the corticospinal tract in both cervical and lumbar spinal cord and reveals circuitry defects, which mainly occur between CSMN and spinal motor neurons in hSOD1G93A transgenic ALS mice. Our findings set the stage for CSMN gene therapy in ALS and related motor neuron diseases. PMID:26704722

  12. Anodal tDCS over the primary motor cortex improves motor imagery benefits on postural control: A pilot study.

    PubMed

    Saruco, Elodie; Rienzo, Franck Di; Nunez-Nagy, Susana; Rubio-Gonzalez, Miguel A; Jackson, Philip L; Collet, Christian; Saimpont, Arnaud; Guillot, Aymeric

    2017-03-28

    Performing everyday actions requires fine postural control, which is a major focus of functional rehabilitation programs. Among the various range of training methods likely to improve balance and postural stability, motor imagery practice (MIP) yielded promising results. Transcranial direct current stimulation (tDCS) applied over the primary motor cortex was also found to potentiate the benefits of MIP on upper-limb motor tasks. Yet, combining both techniques has not been tested for tasks requiring fine postural control. To determine the impact of MIP and the additional effects of tDCS, 14 participants performed a postural control task before and after two experimental (MIP + anodal or sham tDCS over the primary motor cortex) and one control (control task + sham tDCS) conditions, in a double blind randomized study. Data revealed a significant decrease of the time required to perform the postural task. Greater performance gains were recorded when MIP was paired with anodal tDCS and when the task involved the most complex postural adjustments. Altogether, findings highlight short-term effects of MIP on postural control and suggest that combining MIP with tDCS might also be effective in rehabilitation programs for regaining postural skills in easily fatigable persons and neurologic populations.

  13. Reversible Deactivation of Motor Cortex Reveals Functional Connectivity with Posterior Parietal Cortex in the Prosimian Galago (Otolemur garnettii)

    PubMed Central

    Cooke, Dylan F.; Stepniewska, Iwona; Miller, Daniel J.; Kaas, Jon H.

    2015-01-01

    We examined the functional macrocircuitry of frontoparietal networks in the neocortex of prosimian primates (Otolemur garnettii) using a microfluidic thermal regulator to reversibly deactivate selected regions of motor cortex (M1). During deactivation of either forelimb or mouth/face movement domains within M1, we used long-train intracortical microstimulation techniques to evoke movements from the rostral division of posterior parietal cortex (PPCr). We found that deactivation of M1 movement domains in most instances abolished movements evoked in PPCr. The most common effect of deactivating M1 was to abolish evoked movements in a homotopic domain in PPCr. For example, deactivating M1 forelimb lift domains resulted in loss of evoked movement in forelimb domains in PPCr. However, at some sites, we also observed heterotopic effects; deactivating a specific domain in M1 (e.g., forelimb lift) resulted in loss of evoked movement in a different movement domain in PPCr (e.g., hand-to-mouth or eye-blink). At most sites examined in PPCr, rewarming M1 resulted in a reestablishment of the baseline movement at the same amplitude as that observed before cooling. However, at some sites, reactivation did not result in a return to baseline movement or to the full amplitude of the baseline movement. We discuss our findings in the context of frontoparietal circuits and how they may subserve a repertoire of ecologically relevant behaviors. SIGNIFICANCE STATEMENT The posterior parietal cortex (PPC) of primates integrates sensory information used to guide movements. Different modules within PPC and motor cortex (M1) appear to control various motor behaviors (e.g., reaching, defense, and feeding). How these modules work together may vary across species and may explain differences in dexterity and even the capacity for tool use. We investigated the functional connectivity of these modules in galagos, a prosimian primate with relatively simple frontoparietal circuitry. By deactivating a

  14. A motor cortex excitability and gait analysis on Parkinsonian patients.

    PubMed

    Vacherot, François; Attarian, Shahram; Vaugoyeau, Marianne; Azulay, Jean-Philippe

    2010-12-15

    Transcranial magnetic stimulation (TMS) parameters were recorded in a lower limb muscle and correlated with the gait parameters of 25 patients with Parkinson's disease (PD) with and without dopamine substitution treatment (DST) and 10 control subjects. Single and paired-pulse TMS were recorded in the tibialis anterior muscle (TA). Gait analysis was performed using a 3D motion analysis system. Parkinsonian patients (PP) did not differ from the control subjects (CS) in terms of relaxed motor threshold, active motor threshold (AMT), cortical silent period (CSP), motor-evoked potential (MEP) amplitude and area, or paired-pulse TMS with short interstimulus intervals (ISI). At longer ISIs, paired-pulse TMS showed that the amplitudes of the conditioned MEPs were lower in untreated PP than in CS. DST partially compensated for this difference. Gait analysis showed that the gait of PP undergoing no treatment was slower and the stride length shorter than normal. Both of these parameters improved under DST, however. Analysis of data obtained on all the subjects combined showed that both of the latter parameters were correlated with the paired-pulse MEP amplitude and area at longer ISIs. In PP, the cortical areas responsible for the lower limb movements seem to undergo intracortical facilitation (ICF) impairments, whereas the intracortical inhibition process is normal. The ICF level was found to be associated to the stride length and the velocity. The fact that only these two gait parameters were found to be dopa responsive indicates that dopaminergic treatment may improve gait disorders by restoring the ICF.

  15. Aberrant neuromagnetic activation in the motor cortex in children with acute migraine: a magnetoencephalography study.

    PubMed

    Guo, Xinyao; Xiang, Jing; Wang, Yingying; O'Brien, Hope; Kabbouche, Marielle; Horn, Paul; Powers, Scott W; Hershey, Andrew D

    2012-01-01

    Migraine attacks have been shown to interfere with normal function in the brain such as motor or sensory function. However, to date, there has been no clinical neurophysiology study focusing on the motor function in children with migraine during headache attacks. To investigate the motor function in children with migraine, twenty-six children with acute migraine, meeting International Classification of Headache Disorders criteria and age- and gender-matched healthy children were studied using a 275-channel magnetoencephalography system. A finger-tapping paradigm was designed to elicit neuromagnetic activation in the motor cortex. Children with migraine showed significantly prolonged latency of movement-evoked magnetic fields (MEF) during finger movement compared with the controls. The correlation coefficient of MEF latency and age in children with migraine was significantly different from that in healthy controls. The spectral power of high gamma (65-150 Hz) oscillations during finger movement in the primary motor cortex is also significantly higher in children with migraine than in controls. The alteration of responding latency and aberrant high gamma oscillations suggest that the developmental trajectory of motor function in children with migraine is impaired during migraine attacks and/or developmentally delayed. This finding indicates that childhood migraine may affect the development of brain function and result in long-term problems.

  16. Somatosensory response properties of excitatory and inhibitory neurons in rat motor cortex.

    PubMed

    Murray, Peter D; Keller, Asaf

    2011-09-01

    In sensory cortical networks, peripheral inputs differentially activate excitatory and inhibitory neurons. Inhibitory neurons typically have larger responses and broader receptive field tuning compared with excitatory neurons. These differences are thought to underlie the powerful feedforward inhibition that occurs in response to sensory input. In the motor cortex, as in the somatosensory cortex, cutaneous and proprioceptive somatosensory inputs, generated before and during movement, strongly and dynamically modulate the activity of motor neurons involved in a movement and ultimately shape cortical command. Human studies suggest that somatosensory inputs modulate motor cortical activity in a center excitation, surround inhibition manner such that input from the activated muscle excites motor cortical neurons that project to it, whereas somatosensory input from nearby, nonactivated muscles inhibit these neurons. A key prediction of this hypothesis is that inhibitory and excitatory motor cortical neurons respond differently to somatosensory inputs. We tested this prediction with the use of multisite extracellular recordings in anesthetized rats. We found that fast-spiking (presumably inhibitory) neurons respond to tactile and proprioceptive inputs at shorter latencies and larger response magnitudes compared with regular-spiking (presumably excitatory) neurons. In contrast, we found no differences in the receptive field size of these neuronal populations. Strikingly, all fast-spiking neuron pairs analyzed with cross-correlation analysis displayed common excitation, which was significantly more prevalent than common excitation for regular-spiking neuron pairs. These findings suggest that somatosensory inputs preferentially evoke feedforward inhibition in the motor cortex. We suggest that this provides a mechanism for dynamic selection of motor cortical modules during voluntary movements.

  17. Effect of neuromuscular electrical stimulation on motor cortex excitability upon release of tonic muscle contraction.

    PubMed

    Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Higashi, Toshio

    The aim of the present study was to investigate the neurophysiological triggers underlying muscle relaxation from the contracted state, and to examine the mechanisms involved in this process and their subsequent modification by neuromuscular electrical stimulation (NMES). Single-pulse transcranial magnetic stimulation (TMS) was used to produce motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) in 23 healthy participants, wherein motor cortex excitability was examined at the onset of voluntary muscle relaxation following a period of voluntary tonic muscle contraction. In addition, the effects of afferent input on motor cortex excitability, as produced by NMES during muscle contraction, were examined. In particular, two NMES intensities were used for analysis: 1.2 times the sensory threshold and 1.2 times the motor threshold (MT). Participants were directed to execute constant wrist extensions and to release muscle contraction in response to an auditory "GO" signal. MEPs were recorded from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles, and TMS was applied at three different time intervals (30, 60, and 90 ms) after the "GO" signal. Motor cortex excitability was greater during voluntary ECR and FCR relaxation using high-intensity NMES, and relaxation time was decreased. Each parameter differed significantly between 30 and 60 ms. Moreover, in both muscles, SICI was larger in the presence than in the absence of NMES. Therefore, the present findings suggest that terminating a muscle contraction triggers transient neurophysiological mechanisms that facilitate the NMES-induced modulation of cortical motor excitability in the period prior to muscle relaxation. High-intensity NMES might facilitate motor cortical excitability as a function of increased inhibitory intracortical activity, and therefore serve as a transient trigger for the relaxation of prime mover muscles in a therapeutic context.

  18. Neuronal injury in the motor cortex after chronic stroke and lower limb motor impairment: a voxel-based lesion symptom mapping study.

    PubMed

    Reynolds, Alexandria M; Peters, Denise M; Vendemia, Jennifer M C; Smith, Lenwood P; Sweet, Raymond C; Baylis, Gordon C; Krotish, Debra; Fritz, Stacy L

    2014-04-01

    Many studies have examined motor impairments using voxel-based lesion symptom mapping, but few are reported regarding the corresponding relationship between cerebral cortex injury and lower limb motor impairment analyzed using this technique. This study correlated neuronal injury in the cerebral cortex of 16 patients with chronic stroke based on a voxel-based lesion symptom mapping analysis. Neuronal injury in the corona radiata, caudate nucleus and putamen of patients with chronic stroke could predict walking speed. The behavioral measure scores were consistent with motor deficits expected after damage to the cortical motor system due to stroke. These findings suggest that voxel-based lesion symptom mapping may provide a more accurate prognosis of motor recovery from chronic stroke according to neuronal injury in cerebral motor cortex.

  19. Neuronal injury in the motor cortex after chronic stroke and lower limb motor impairment: a voxel-based lesion symptom mapping study

    PubMed Central

    Reynolds, Alexandria M.; Peters, Denise M.; Vendemia, Jennifer M. C.; Smith, Lenwood P.; Sweet, Raymond C.; Baylis, Gordon C.; Krotish, Debra; Fritz, Stacy L.

    2014-01-01

    Many studies have examined motor impairments using voxel-based lesion symptom mapping, but few are reported regarding the corresponding relationship between cerebral cortex injury and lower limb motor impairment analyzed using this technique. This study correlated neuronal injury in the cerebral cortex of 16 patients with chronic stroke based on a voxel-based lesion symptom mapping analysis. Neuronal injury in the corona radiata, caudate nucleus and putamen of patients with chronic stroke could predict walking speed. The behavioral measure scores were consistent with motor deficits expected after damage to the cortical motor system due to stroke. These findings suggest that voxel-based lesion symptom mapping may provide a more accurate prognosis of motor recovery from chronic stroke according to neuronal injury in cerebral motor cortex. PMID:25206888

  20. Intrafusal motor innervation: a quantitative histological analysis of tenuissimus muscle spindles in the cat.

    PubMed Central

    Banks, R W

    1994-01-01

    A quantitative analysis of the motor innervation of intrafusal muscle fibres is described, based on teased silver-impregnated spindles of the tenuissimus muscle of the cat. Included in the analysis are the number and distribution of intrafusal branches of both skeletofusimotor (beta) and purely fusimotor (gamma) axons, and the form of their endings. The number of axonal branches per spindle was found to follow binomial probability distributions, as had previously been shown for the afferent axons. There was a strong correlation between the numbers of gamma intrafusal branches and afferent axons, but none for the intrafusal branches of beta axons. The degree of segregation of gamma input to bag2 and chain fibres was assessed and was found, among other things, to be related to the presence of secondary sensory endings in the same pole. In this and other respects it did not appear to have the properties that would be expected if independent activation of the bag2 and chain fibres were to be functionally important. Morphometric analysis of the motor endings supplied to bag2 or chain fibres by gamma axons revealed some differences between those of intrafusal branches with segregated as opposed to unsegregated distributions, but this cannot be taken as evidence of more than one type of static gamma motoneuron because of the likely contribution of other influential factors such as fibre size. Finally, the relevance of studies on intrafusal motor innervation to the concept of the motor unit and its development are discussed. Images Fig. 1 Fig. 2 PMID:7559110

  1. Hindlimb spasticity after unilateral motor cortex lesion in rats is reduced by contralateral nerve root transfer

    PubMed Central

    Zong, Haiyang; Ma, Fenfen; Zhang, Laiyin; Lu, Huiping; Gong, Jingru; Cai, Min; Lin, Haodong; Zhu, Yizhun; Hou, Chunlin

    2016-01-01

    Lower extremity spasticity is a common sequela among patients with acquired brain injury. The optimum treatment remains controversial. The aim of our study was to test the feasibility and effectiveness of contralateral nerve root transfer in reducing post stroke spasticity of the affected hindlimb muscles in rats. In our study, we for the first time created a novel animal hindlimb spastic hemiplegia model in rats with photothrombotic lesion of unilateral motor cortex and we established a novel surgical procedure in reducing motor cortex lesion-induced hindlimb spastic hemiplegia in rats. Thirty six rats were randomized into three groups. In group A, rats received sham operation. In group B, rats underwent unilateral hindlimb motor cortex lesion. In group C, rats underwent unilateral hindlimb cortex lesion followed by contralateral L4 ventral root transfer to L5 ventral root of the affected side. Footprint analysis, Hoffmann reflex (H-reflex), cholera toxin subunit B (CTB) retrograde tracing of gastrocnemius muscle (GM) motoneurons and immunofluorescent staining of vesicle glutamate transporter 1 (VGLUT1) on CTB-labelled motoneurons were used to assess spasticity of the affected hindlimb. Sixteen weeks postoperatively, toe spread and stride length recovered significantly in group C compared with group B (P<0.001). Hmax (H-wave maximum amplitude)/Mmax (M-wave maximum amplitude) ratio of gastrocnemius and plantaris muscles (PMs) significantly reduced in group C (P<0.01). Average VGLUT1 positive boutons per CTB-labelled motoneurons significantly reduced in group C (P<0.001). We demonstrated for the first time that contralateral L4 ventral root transfer to L5 ventral root of the affected side was effective in relieving unilateral motor cortex lesion-induced hindlimb spasticity in rats. Our data indicated that this could be an alternative treatment for unilateral lower extremity spasticity after brain injury. Therefore, contralateral neurotization may exert a potential

  2. The prefrontal cortex achieves inhibitory control by facilitating subcortical motor pathway connectivity.

    PubMed

    Rae, Charlotte L; Hughes, Laura E; Anderson, Michael C; Rowe, James B

    2015-01-14

    Communication between the prefrontal cortex and subcortical nuclei underpins the control and inhibition of behavior. However, the interactions in such pathways remain controversial. Using a stop-signal response inhibition task and functional imaging with analysis of effective connectivity, we show that the lateral prefrontal cortex influences the strength of communication between regions in the frontostriatal motor system. We compared 20 generative models that represented alternative interactions between the inferior frontal gyrus, presupplementary motor area (preSMA), subthalamic nucleus (STN), and primary motor cortex during response inhibition. Bayesian model selection revealed that during successful response inhibition, the inferior frontal gyrus modulates an excitatory influence of the preSMA on the STN, thereby amplifying the downstream polysynaptic inhibition from the STN to the motor cortex. Critically, the strength of the interaction between preSMA and STN, and the degree of modulation by the inferior frontal gyrus, predicted individual differences in participants' stopping performance (stop-signal reaction time). We then used diffusion-weighted imaging with tractography to assess white matter structure in the pathways connecting these three regions. The mean diffusivity in tracts between preSMA and the STN, and between the inferior frontal gyrus and STN, also predicted individual differences in stopping efficiency. Finally, we found that white matter structure in the tract between preSMA and STN correlated with effective connectivity of the same pathway, providing important cross-modal validation of the effective connectivity measures. Together, the results demonstrate the network dynamics and modulatory role of the prefrontal cortex that underpin individual differences in inhibitory control.

  3. Sensorimotor integration for speech motor learning involves the inferior parietal cortex.

    PubMed

    Shum, Mamie; Shiller, Douglas M; Baum, Shari R; Gracco, Vincent L

    2011-12-01

    Sensorimotor integration is important for motor learning. The inferior parietal lobe, through its connections with the frontal lobe and cerebellum, has been associated with multisensory integration and sensorimotor adaptation for motor behaviors other than speech. In the present study, the contribution of the inferior parietal cortex to speech motor learning was evaluated using repetitive transcranial magnetic stimulation (rTMS) prior to a speech motor adaptation task. Subjects' auditory feedback was altered in a manner consistent with the auditory consequences of an unintended change in tongue position during speech production, and adaptation performance was used to evaluate sensorimotor plasticity and short-term learning. Prior to the feedback alteration, rTMS or sham stimulation was applied over the left supramarginal gyrus (SMG). Subjects who underwent the sham stimulation exhibited a robust adaptive response to the feedback alteration whereas subjects who underwent rTMS exhibited a diminished adaptive response. The results suggest that the inferior parietal region, in and around SMG, plays a role in sensorimotor adaptation for speech. The interconnections of the inferior parietal cortex with inferior frontal cortex, cerebellum and primary sensory areas suggest that this region may be an important component in learning and adapting sensorimotor patterns for speech.

  4. Properties and fate of oligodendrocyte progenitor cells in the corpus callosum, motor cortex, and piriform cortex of the mouse.

    PubMed

    Clarke, Laura E; Young, Kaylene M; Hamilton, Nicola B; Li, Huiliang; Richardson, William D; Attwell, David

    2012-06-13

    Oligodendrocyte progenitor cells (OPCs) in the postnatal mouse corpus callosum (CC) and motor cortex (Ctx) reportedly generate only oligodendrocytes (OLs), whereas those in the piriform cortex may also generate neurons. OPCs have also been subdivided based on their expression of voltage-gated ion channels, ability to respond to neuronal activity, and proliferative state. To determine whether OPCs in the piriform cortex have inherently different physiological properties from those in the CC and Ctx, we studied acute brain slices from postnatal transgenic mice in which GFP expression identifies OL lineage cells. We whole-cell patch clamped GFP-expressing (GFP(+)) cells within the CC, Ctx, and anterior piriform cortex (aPC) and used prelabeling with 5-ethynyl-2'-deoxyuridine (EdU) to assess cell proliferation. After recording, slices were immunolabeled and OPCs were defined by strong expression of NG2. NG2(+) OPCs in the white and gray matter proliferated and coexpressed PDGFRα and voltage-gated Na(+) channels (I(Na)). Approximately 70% of OPCs were capable of generating regenerative depolarizations. In addition to OLIG2(+) NG2(+) I(Na)(+) OPCs and OLIG2(+) NG2(neg) I(Na)(neg) OLs, we identified cells with low levels of NG2 limited to the soma or the base of some processes. These cells had a significantly reduced I(Na) and a reduced ability to incorporate EdU when compared with OPCs and probably correspond to early differentiating OLs. By combining EdU labeling and lineage tracing using Pdgfrα-CreER(T2) : R26R-YFP transgenic mice, we double labeled OPCs and traced their fate in the postnatal brain. These OPCs generated OLs but did not generate neurons in the aPC or elsewhere at any time that we examined.

  5. Exuberant projection into the corpus callosum from the visual cortex of newborn cats.

    PubMed

    Innocenti, G M; Fiore, L; Caminiti, R

    1977-04-01

    In the first postnatal week, neurones projecting into the corpus callosum can be identified in kitten's visual cortex by retrograde transport of HRP. The neurones are located in layers III, IV, and VI. The region of cortex which gives rise to the callosal projection extends beyond its adult boundaries over most of area 17, 18, 19 and in the suprasylvian sulcus.

  6. Noninvasive determination of speech dominance by single magnetic stimulation of the bilateral hand motor cortex.

    PubMed

    Tokimura, Hiroshi; Imamura, Shin-Ichi; Arita, Kazunori

    2012-01-01

    Magnetic stimulation of the hand area of the motor cortex in both hemispheres was performed at rest and during reading aloud to observe modulated facilitation of hand muscle motor potentials in 6 right-handed patients, with supratentorial lesions but no motor impairment or aphasia, who had undergone the Wada test to determine speech dominance, showing that 5 were left hemisphere dominant and one was bilateral hemisphere dominant. Motor potentials were facilitated during reading aloud in only the right hand in 3 patients, all left hemisphere dominant, greater in the right hand in one, left hemisphere dominant, and greater in the left hand in one patient, bilateral hemisphere dominant. Based on these results we defined a laterality index which was consistent with the Wada test results. Magnetic stimulation may prove useful for determining cerebral dominance, as our method correlates well with the Wada test, and is safe, convenient, and inexpensive.

  7. Effects of chronic cochlear electrical stimulation after an extended period of profound deafness on primary auditory cortex organization in cats.

    PubMed

    Fallon, James B; Shepherd, Robert K; Irvine, Dexter R F

    2014-03-01

    Extended periods of deafness have profound effects on central auditory system function and organization. Neonatal deafening results in loss of the normal cochleotopic organization of the primary auditory cortex (AI), but environmentally-derived intracochlear electrical stimulation, via a cochlear implant, initiated shortly after deafening, can prevent this loss. We investigated whether such stimulation initiated after an extended period of deafness can restore cochleotopy. In two groups of neonatally-deafened cats, a multi-channel intracochlear electrode array was implanted at 8 weeks of age. One group received only minimal stimulation, associated with brief recordings at 4-6-week intervals, over the following 6 months to check the efficacy of the implant. In the other group, this 6-month period was followed by 6 months of near-continuous intracochlear electrical stimulation from a modified clinical cochlear implant system. We recorded multi-unit clusters in the auditory cortex and used two different methods to define the region of interest in the putative AI. There was no evidence of cochleotopy in any of the minimally stimulated animals, confirming our earlier finding. In three of six chronically stimulated cats there was clear evidence of AI cochleotopy, and in a fourth cat in which the majority of penetrations were in the anterior auditory field there was clear evidence of cochleotopy in that field. The finding that chronic intracochlear electrical stimulation after an extended period of deafness is able to restore cochleotopy in some (but not all) cases has implications for the performance of patients implanted after an extended period of deafness.

  8. Parallel pathways from motor and somatosensory cortex for controlling whisker movements in mice.

    PubMed

    Sreenivasan, Varun; Karmakar, Kajari; Rijli, Filippo M; Petersen, Carl C H

    2015-02-01

    Mice can gather tactile sensory information by actively moving their whiskers to palpate objects in their immediate surroundings. Whisker sensory perception therefore requires integration of sensory and motor information, which occurs prominently in the neocortex. The signalling pathways from the neocortex for controlling whisker movements are currently poorly understood in mice. Here, we delineate two pathways, one originating from primary whisker somatosensory cortex (wS1) and the other from whisker motor cortex (wM1), that control qualitatively distinct movements of contralateral whiskers. Optogenetic stimulation of wS1 drove retraction of contralateral whiskers while stimulation of wM1 drove rhythmic whisker protraction. To map brainstem pathways connecting these cortical areas to whisker motor neurons, we used a combination of anterograde tracing using adenoassociated virus injected into neocortex and retrograde tracing using monosynaptic rabies virus injected into whisker muscles. Our data are consistent with wS1 driving whisker retraction by exciting glutamatergic premotor neurons in the rostral spinal trigeminal interpolaris nucleus, which in turn activate the motor neurons innervating the extrinsic retractor muscle nasolabialis. The rhythmic whisker protraction evoked by wM1 stimulation might be driven by excitation of excitatory and inhibitory premotor neurons in the brainstem reticular formation innervating both intrinsic and extrinsic muscles. Our data therefore begin to unravel the neuronal circuits linking the neocortex to whisker motor neurons.

  9. Task-dependent modulation of excitatory and inhibitory functions within the human primary motor cortex.

    PubMed

    Tinazzi, Michele; Farina, Simona; Tamburin, Stefano; Facchini, Stefano; Fiaschi, Antonio; Restivo, Domenico; Berardelli, Alfredo

    2003-05-01

    We evaluated motor evoked potentials (MEPs) and duration of the cortical silent period (CSP) from the right first dorsal interosseous (FDI) muscle to transcranial magnetic stimulation (TMS) of the left motor cortex in ten healthy subjects performing different manual tasks. They abducted the index finger alone, pressed a strain gauge with the thumb and index finger in a pincer grip, and squeezed a 4-cm brass cylinder with all digits in a power grip. The level of FDI EMG activity across tasks was kept constant by providing subjects with acoustic-visual feedback of their muscle activity. The TMS elicited larger amplitude FDI MEPs during pincer and power grip than during the index finger abduction task, and larger amplitude MEPs during pincer gripping than during power gripping. The CSP was shorter during pincer and power grip than during the index finger abduction task and shorter during power gripping than during pincer gripping. These results suggest excitatory and inhibitory task-dependent changes in the motor cortex. Complex manual tasks (pincer and power gripping) elicit greater motor cortical excitation than a simple task (index finger abduction) presumably because they activate multiple synergistic muscles thus facilitating corticomotoneurons. The finger abduction task probably yielded greater motor cortical inhibition than the pincer and power tasks because muscles uninvolved in the task activated the cortical inhibitory circuit. Increased cortical excitatory and inhibitory functions during precision tasks (pincer gripping) probably explain why MEPs have larger amplitudes and CSPs have longer durations during pincer gripping than during power gripping.

  10. Neuroplasticity Changes on Human Motor Cortex Induced by Acupuncture Therapy: A Preliminary Study.

    PubMed

    Yang, Yi; Eisner, Ines; Chen, Siqi; Wang, Shaosong; Zhang, Fan; Wang, Linpeng

    2017-01-01

    While neuroplasticity changes measured by transcranial magnetic stimulation have been proved to be highly correlated to motor recovery and have been tested in various forms of interventions, it has not been applied to investigate the neurophysiologic mechanism of acupuncture therapy. The aim of this study is to investigate neuroplasticity changes induced by a single session of acupuncture therapy in healthy adults, regarding the excitability change on bilateral primary motor cortex and interhemispheric inhibition. Ten subjects took a 30-minute acupuncture therapy and the same length relaxing phase in separate days. Transcranial magnetic stimulation measures, including resting motor threshold, amplitudes of motor-evoked potential, and interhemispheric inhibition, were assessed before and 10 minutes after intervention. Acupuncture treatment showed significant changes on potential amplitude from both ipsilateral and contralateral hemispheres to acupuncture compared to baseline. Also, interhemispheric inhibition from the contralateral motor cortex to the opposite showed a significant decline. The results indicated that corticomotoneuronal excitability and interhemispheric competition could be modulated by acupuncture therapy on healthy subjects. The following question about whether these changes will be observed in the same way on stroke patients and whether they correlate with the therapeutic effect on movement need to be answered by following studies. This trial is registered with ISRCTN13074245.

  11. Theta burst stimulation over the primary motor cortex does not induce cortical plasticity in Parkinson's disease.

    PubMed

    Eggers, Carsten; Fink, Gereon R; Nowak, Dennis A

    2010-10-01

    The purpose of this study was to investigate whether a period of continuous theta burst stimulation (cTBS) induces cortical plasticity and thus improves bradykinesia of the upper limb in Parkinson's disease. In eight patients with Parkinson's disease (two females; mean age: 68.5 ± 5 years; disease duration: 4 ± 3 years) electrophysiological (motor evoked potentials, contralateral and ipsilateral silent period) and behavioural (Purdue pegboard test, UPDRS motor subscore) parameters were evaluated before (baseline condition) and after a 40-s period of (1) real or (2) sham continuous theta burst stimulation over the primary motor cortex contralateral to the more affected body side off dopaminergic drugs. Compared to baseline, cTBS did change neither measures of cortical excitability nor behavioural measures. cTBS over the primary motor cortex does not impact on cortical excitability or motor function of the upper limb in Parkinson's disease. We interpret these data to reflect impaired cortical plasticity in Parkinson's disease. This study is an important contribution to the knowledge about impaired plasticity in Parkinson's disease.

  12. Primary motor cortex functionally contributes to language comprehension: An online rTMS study.

    PubMed

    Vukovic, Nikola; Feurra, Matteo; Shpektor, Anna; Myachykov, Andriy; Shtyrov, Yury

    2017-02-01

    Among various questions pertinent to grounding human cognitive functions in a neurobiological substrate, the association between language and motor brain structures is a particularly debated one in neuroscience and psychology. While many studies support a broadly distributed model of language and semantics grounded, among other things, in the general modality-specific systems, theories disagree as to whether motor and sensory cortex activity observed during language processing is functional or epiphenomenal. Here, we assessed the role of motor areas in linguistic processing by investigating the responses of 28 healthy volunteers to different word types in semantic and lexical decision tasks, following repetitive transcranial magnetic stimulation (rTMS) of primary motor cortex. We found that early rTMS (delivered within 200ms of word onset) produces a left-lateralised and meaning-specific change in reaction speed, slowing down behavioural responses to action-related words, and facilitating abstract words - an effect present only during semantic, but not lexical, decision. We interpret these data in light of action-perception theory of language, bolstering the claim that motor cortical areas play a functional role in language comprehension.

  13. Neuroplasticity Changes on Human Motor Cortex Induced by Acupuncture Therapy: A Preliminary Study

    PubMed Central

    Eisner, Ines; Chen, Siqi; Wang, Shaosong; Zhang, Fan

    2017-01-01

    While neuroplasticity changes measured by transcranial magnetic stimulation have been proved to be highly correlated to motor recovery and have been tested in various forms of interventions, it has not been applied to investigate the neurophysiologic mechanism of acupuncture therapy. The aim of this study is to investigate neuroplasticity changes induced by a single session of acupuncture therapy in healthy adults, regarding the excitability change on bilateral primary motor cortex and interhemispheric inhibition. Ten subjects took a 30-minute acupuncture therapy and the same length relaxing phase in separate days. Transcranial magnetic stimulation measures, including resting motor threshold, amplitudes of motor-evoked potential, and interhemispheric inhibition, were assessed before and 10 minutes after intervention. Acupuncture treatment showed significant changes on potential amplitude from both ipsilateral and contralateral hemispheres to acupuncture compared to baseline. Also, interhemispheric inhibition from the contralateral motor cortex to the opposite showed a significant decline. The results indicated that corticomotoneuronal excitability and interhemispheric competition could be modulated by acupuncture therapy on healthy subjects. The following question about whether these changes will be observed in the same way on stroke patients and whether they correlate with the therapeutic effect on movement need to be answered by following studies. This trial is registered with ISRCTN13074245. PMID:28293438

  14. Comparison of Huntington's disease CAG Repeat Length Stability in Human Motor Cortex and Cingulate Gyrus.

    PubMed

    Geraerts, Fiona C A; Snell, Russell G; Faull, Richard L M; Williams, Liam; Jacobsen, Jessie C; Reid, Suzanne J

    2016-10-01

    Huntington's disease is caused by expansion of the CAG repeat in Huntingtin. This repeat has shown tissue-specific instability in mouse models and in a small number of post-mortem human samples. We used small-pool PCR to generate a modified instability index to quantify CAG instability within two brain regions from six human samples where cell loss has been associated with motor and mood symptoms: the motor cortex and cingulate gyrus. The expanded allele demonstrated instability in both regions, with minimal instability in the unexpanded allele. Region-specific differences were not observed, suggesting symptomatology may not be determined by repeat length instability.

  15. You can count on the motor cortex: Finger counting habits modulate motor cortex activation evoked by numbers

    PubMed Central

    Tschentscher, Nadja; Hauk, Olaf; Fischer, Martin H.; Pulvermüller, Friedemann

    2012-01-01

    The embodied cognition framework suggests that neural systems for perception and action are engaged during higher cognitive processes. In an event-related fMRI study, we tested this claim for the abstract domain of numerical symbol processing: is the human cortical motor system part of the representation of numbers, and is organization of numerical knowledge influenced by individual finger counting habits? Developmental studies suggest a link between numerals and finger counting habits due to the acquisition of numerical skills through finger counting in childhood. In the present study, digits 1 to 9 and the corresponding number words were presented visually to adults with different finger counting habits, i.e. left- and right-starters who reported that they usually start counting small numbers with their left and right hand, respectively. Despite the absence of overt hand movements, the hemisphere contralateral to the hand used for counting small numbers was activated when small numbers were presented. The correspondence between finger counting habits and hemispheric motor activation is consistent with an intrinsic functional link between finger counting and number processing. PMID:22133748

  16. Cognitive control and right ventrolateral prefrontal cortex: reflexive reorienting, motor inhibition, and action updating

    PubMed Central

    Levy, Benjamin J.; Wagner, Anthony D.

    2011-01-01

    Delineating the functional organization of the prefrontal cortex is central to advancing models of goal-directed cognition. Considerable evidence indicates that specific forms of cognitive control are associated with distinct subregions of the left ventrolateral prefrontal cortex (VLPFC), but less is known about functional specialization within the right VLPFC. We report a functional MRI meta-analysis of two prominent theories of right VLPFC function: stopping of motor responses and reflexive orienting to abrupt perceptual onsets. Along with a broader review of right VLPFC function, extant data indicate that stopping and reflexive orienting similarly recruit the inferior frontal junction (IFJ), suggesting that IFJ supports the detection of behaviorally relevant stimuli. By contrast, other right VLPFC subregions are consistently active during motor inhibition, but not reflexive reorienting tasks, with posterior-VLPFC being active during the updating of action plans and mid-VLPFC responding to decision uncertainty. These results highlight the rich functional heterogeneity that exists within right VLPFC. PMID:21486295

  17. Rapid Integration of Artificial Sensory Feedback during Operant Conditioning of Motor Cortex Neurons.

    PubMed

    Prsa, Mario; Galiñanes, Gregorio L; Huber, Daniel

    2017-02-22

    Neuronal motor commands, whether generating real or neuroprosthetic movements, are shaped by ongoing sensory feedback from the displacement being produced. Here we asked if cortical stimulation could provide artificial feedback during operant conditioning of cortical neurons. Simultaneous two-photon imaging and real-time optogenetic stimulation were used to train mice to activate a single neuron in motor cortex (M1), while continuous feedback of its activity level was provided by proportionally stimulating somatosensory cortex. This artificial signal was necessary to rapidly learn to increase the conditioned activity, detect correct performance, and maintain the learned behavior. Population imaging in M1 revealed that learning-related activity changes are observed in the conditioned cell only, which highlights the functional potential of individual neurons in the neocortex. Our findings demonstrate the capacity of animals to use an artificially induced cortical channel in a behaviorally relevant way and reveal the remarkable speed and specificity at which this can occur.

  18. Dissociating Contributions of the Motor Cortex to Speech Perception and Response Bias by Using Transcranial Magnetic Stimulation.

    PubMed

    Smalle, Eleonore H M; Rogers, Jack; Möttönen, Riikka

    2015-10-01

    Recent studies using repetitive transcranial magnetic stimulation (TMS) have demonstrated that disruptions of the articulatory motor cortex impair performance in demanding speech perception tasks. These findings have been interpreted as support for the idea that the motor cortex is critically involved in speech perception. However, the validity of this interpretation has been called into question, because it is unknown whether the TMS-induced disruptions in the motor cortex affect speech perception or rather response bias. In the present TMS study, we addressed this question by using signal detection theory to calculate sensitivity (i.e., d') and response bias (i.e., criterion c). We used repetitive TMS to temporarily disrupt the lip or hand representation in the left motor cortex. Participants discriminated pairs of sounds from a "ba"-"da" continuum before TMS, immediately after TMS (i.e., during the period of motor disruption), and after a 30-min break. We found that the sensitivity for between-category pairs was reduced during the disruption of the lip representation. In contrast, disruption of the hand representation temporarily reduced response bias. This double dissociation indicates that the hand motor cortex contributes to response bias during demanding discrimination tasks, whereas the articulatory motor cortex contributes to perception of speech sounds.

  19. Dissociating Contributions of the Motor Cortex to Speech Perception and Response Bias by Using Transcranial Magnetic Stimulation

    PubMed Central

    Smalle, Eleonore H. M.; Rogers, Jack; Möttönen, Riikka

    2015-01-01

    Recent studies using repetitive transcranial magnetic stimulation (TMS) have demonstrated that disruptions of the articulatory motor cortex impair performance in demanding speech perception tasks. These findings have been interpreted as support for the idea that the motor cortex is critically involved in speech perception. However, the validity of this interpretation has been called into question, because it is unknown whether the TMS-induced disruptions in the motor cortex affect speech perception or rather response bias. In the present TMS study, we addressed this question by using signal detection theory to calculate sensitivity (i.e., d′) and response bias (i.e., criterion c). We used repetitive TMS to temporarily disrupt the lip or hand representation in the left motor cortex. Participants discriminated pairs of sounds from a “ba”–“da” continuum before TMS, immediately after TMS (i.e., during the period of motor disruption), and after a 30-min break. We found that the sensitivity for between-category pairs was reduced during the disruption of the lip representation. In contrast, disruption of the hand representation temporarily reduced response bias. This double dissociation indicates that the hand motor cortex contributes to response bias during demanding discrimination tasks, whereas the articulatory motor cortex contributes to perception of speech sounds. PMID:25274987

  20. Intracortical Microstimulation Maps of Motor, Somatosensory, and Posterior Parietal Cortex in Tree Shrews (Tupaia belangeri) Reveal Complex Movement Representations.

    PubMed

    Baldwin, Mary K L; Cooke, Dylan F; Krubitzer, Leah

    2017-02-01

    Long-train intracortical microstimulation (LT-ICMS) is a popular method for studying the organization of motor and posterior parietal cortex (PPC) in mammals. In primates, LT-ICMS evokes both multijoint and multiple-body-part movements in primary motor, premotor, and PPC. In rodents, LT-ICMS evokes complex movements of a single limb in motor cortex. Unfortunately, very little is known about motor/PPC organization in other mammals. Tree shrews are closely related to both primates and rodents and could provide insights into the evolution of complex movement domains in primates. The present study investigated the extent of cortex in which movements could be evoked with ICMS and the characteristics of movements elicited using both short train (ST) and LT-ICMS in tree shrews. We demonstrate that LT-ICMS and ST-ICMS maps are similar, with the movements elicited with ST-ICMS being truncated versions of those elicited with LT-ICMS. In addition, LT-ICMS-evoked complex movements within motor cortex similar to those in rodents. More complex movements involving multiple body parts such as the hand and mouth were also elicited in motor cortex and PPC, as in primates. Our results suggest that complex movement networks present in PPC and motor cortex were present in mammals prior to the emergence of primates.

  1. Motor Training Promotes Both Synaptic and Intrinsic Plasticity of Layer II/III Pyramidal Neurons in the Primary Motor Cortex

    PubMed Central

    Kida, Hiroyuki; Tsuda, Yasumasa; Ito, Nana; Yamamoto, Yui; Owada, Yuji; Kamiya, Yoshinori; Mitsushima, Dai

    2016-01-01

    Motor skill training induces structural plasticity at dendritic spines in the primary motor cortex (M1). To further analyze both synaptic and intrinsic plasticity in the layer II/III area of M1, we subjected rats to a rotor rod test and then prepared acute brain slices. Motor skill consistently improved within 2 days of training. Voltage clamp analysis showed significantly higher α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/N-methyl-d-aspartate (AMPA/NMDA) ratios and miniature EPSC amplitudes in 1-day trained rats compared with untrained rats, suggesting increased postsynaptic AMPA receptors in the early phase of motor learning. Compared with untrained controls, 2-days trained rats showed significantly higher miniature EPSC amplitude and frequency. Paired-pulse analysis further demonstrated lower rates in 2-days trained rats, suggesting increased presynaptic glutamate release during the late phase of learning. One-day trained rats showed decreased miniature IPSC frequency and increased paired-pulse analysis of evoked IPSC, suggesting a transient decrease in presynaptic γ-aminobutyric acid (GABA) release. Moreover, current clamp analysis revealed lower resting membrane potential, higher spike threshold, and deeper afterhyperpolarization in 1-day trained rats—while 2-days trained rats showed higher membrane potential, suggesting dynamic changes in intrinsic properties. Our present results indicate dynamic changes in glutamatergic, GABAergic, and intrinsic plasticity in M1 layer II/III neurons after the motor training. PMID:27193420

  2. Mapping Horizontal Spread of Activity in Monkey Motor Cortex Using Single Pulse Microstimulation

    PubMed Central

    Riehle, Alexa; Brochier, Thomas G.

    2016-01-01

    Anatomical studies have demonstrated that distant cortical points are interconnected through long range axon collaterals of pyramidal cells. However, the functional properties of these intrinsic synaptic connections, especially their relationship with the cortical representations of body movements, have not been systematically investigated. To address this issue, we used multielectrode arrays chronically implanted in the motor cortex of two rhesus monkeys to analyze the effects of single-pulse intracortical microstimulation (sICMS) applied at one electrode on the neuronal activities recorded at all other electrodes. The temporal and spatial distribution of the evoked responses of single and multiunit activities was quantified to determine the properties of horizontal propagation. The typical responses were characterized by a brief excitatory peak followed by inhibition of longer duration. Significant excitatory responses to sICMS could be evoked up to 4 mm away from the stimulation site, but the strength of the response decreased exponentially and its latency increased linearly with the distance. We then quantified the direction and strength of the propagation in relation to the somatotopic organization of the motor cortex. We observed that following sICMS the propagation of neural activity is mainly directed rostro-caudally near the central sulcus but follows medio-lateral direction at the most anterior electrodes. The fact that these interactions are not entirely symmetrical may characterize a critical functional property of the motor cortex for the control of upper limb movements. Overall, these results support the assumption that the motor cortex is not functionally homogeneous but forms a complex network of interacting subregions. PMID:28018182

  3. Hemispheric asymmetry in cerebrovascular reactivity of the human primary motor cortex: an in vivo study at 7 T.

    PubMed

    Driver, Ian D; Andoh, Jamila; Blockley, Nicholas P; Francis, Susan T; Gowland, Penny A; Paus, Tomáš

    2015-05-01

    Current functional MRI (fMRI) approaches assess underlying neuronal activity through monitoring the related local variations in cerebral blood oxygenation, blood volume and blood flow. This vascular response is likely to vary across brain regions and across individuals, depending on the composition of the local vascular bed and on the vascular capacity to dilate. The most widely used technique uses the blood oxygen level dependent (BOLD) fMRI signal, which arises from a complex combination of all of these factors. The model of handedness provides a case where one brain region (dominant motor cortex) is known to have a stronger BOLD response over another (non-dominant motor cortex) during hand motor task performance. We predict that this is accompanied by a higher vascular reactivity in the dominant motor cortex, when compared with the non-dominant motor cortex. Precise measurement of end-tidal CO2 and a novel sinusoidal CO2 respiratory challenge were combined with the high sensitivity and finer spatial resolution available for fMRI at 7 T to measure BOLD cerebrovascular reactivity (CVR) in eight healthy male participants. BOLD CVR was compared between the left (dominant) and right (non-dominant) primary motor cortices of right-handed adults. Hemispheric asymmetry in vascular reactivity was predicted and observed in the primary motor cortex (left CVR = 0.60 ± 0.15%/mm Hg; right CVR = 0.47 ± 0.08%/mm Hg; left CVR > right CVR, P = 0.04), the first reported evidence of such a vascular difference. These findings demonstrate a cerebral vascular asymmetry between the left and right primary motor cortex. The origin of this asymmetry largely arises from the contribution of large draining veins. This work has implications for future motor laterality studies that use BOLD, and it is also suggestive of a vascular plasticity in the human primary motor cortex.

  4. Motor Cortical Stimulation Promotes Synaptic Plasticity and Behavioral Improvements Following Sensorimotor Cortex Lesions

    PubMed Central

    Adkins, DeAnna L.; Hsu, J. Edward; Jones, Theresa A.

    2010-01-01

    Cortical stimulation (CS) as a means to modulate regional activity and excitability in cortex is emerging as a promising approach for facilitating rehabilitative interventions after brain damage, including stroke. In this study, we investigated whether CS-induced functional improvements are linked with synaptic plasticity in peri-infarct cortex and vary with the severity of impairments. Adult rats that were proficient in skilled reaching received subtotal unilateral ischemic sensorimotor cortex (SMC) lesions and implantation of chronic epidural electrodes over remaining motor cortex. Based on the initial magnitude of reaching deficits, rats were divided into severely and moderately impaired subgroups. Beginning two weeks post-surgery, rats received 100 Hz cathodal CS at 50% of movement thresholds or no-stimulation control procedures (NoCS) during 18 days of rehabilitative training on a reaching task. Stereological electron microscopy methods were used to quantify axodendritic synapse subtypes in motor cortical layer V underlying the electrode. In moderately, but not severely impaired rats, CS significantly enhanced recovery of reaching success. Sensitive movement analyses revealed that CS partially normalized reaching movements in both impairment subgroups compared to NoCS. Additionally, both CS subgroups had significantly greater density of axodendritic synapses and moderately impaired CS rats had increases in presumed efficacious synapse subtypes (perforated and multiple synapses) in stimulated cortex compared to NoCS. Synaptic density was positively correlated with post-rehabilitation reaching success. In addition to providing further support that CS can promote functional recovery, these findings suggest that CS-induced functional improvements may be mediated by synaptic structural plasticity in stimulated cortex. PMID:18448100

  5. Cortico-fugal output from visual cortex promotes plasticity of innate motor behaviour.

    PubMed

    Liu, Bao-Hua; Huberman, Andrew D; Scanziani, Massimo

    2016-10-20

    The mammalian visual cortex massively innervates the brainstem, a phylogenetically older structure, via cortico-fugal axonal projections. Many cortico-fugal projections target brainstem nuclei that mediate innate motor behaviours, but the function of these projections remains poorly understood. A prime example of such behaviours is the optokinetic reflex (OKR), an innate eye movement mediated by the brainstem accessory optic system, that stabilizes images on the retina as the animal moves through the environment and is thus crucial for vision. The OKR is plastic, allowing the amplitude of this reflex to be adaptively adjusted relative to other oculomotor reflexes and thereby ensuring image stability throughout life. Although the plasticity of the OKR is thought to involve subcortical structures such as the cerebellum and vestibular nuclei, cortical lesions have suggested that the visual cortex might also be involved. Here we show that projections from the mouse visual cortex to the accessory optic system promote the adaptive plasticity of the OKR. OKR potentiation, a compensatory plastic increase in the amplitude of the OKR in response to vestibular impairment, is diminished by silencing visual cortex. Furthermore, targeted ablation of a sparse population of cortico-fugal neurons that specifically project to the accessory optic system severely impairs OKR potentiation. Finally, OKR potentiation results from an enhanced drive exerted by the visual cortex onto the accessory optic system. Thus, cortico-fugal projections to the brainstem enable the visual cortex, an area that has been principally studied for its sensory processing function, to plastically adapt the execution of innate motor behaviours.

  6. Fezf2 expression in layer 5 projection neurons of mature mouse motor cortex.

    PubMed

    Tantirigama, Malinda L S; Oswald, Manfred J; Clare, Alison J; Wicky, Hollie E; Day, Robert C; Hughes, Stephanie M; Empson, Ruth M

    2016-03-01

    The mature cerebral cortex contains a wide diversity of neuron phenotypes. This diversity is specified during development by neuron-specific expression of key transcription factors, some of which are retained for the life of the animal. One of these key developmental transcription factors that is also retained in the adult is Fezf2, but the neuron types expressing it in the mature cortex are unknown. With a validated Fezf2-Gfp reporter mouse, whole-cell electrophysiology with morphology reconstruction, cluster analysis, in vivo retrograde labeling, and immunohistochemistry, we identify a heterogeneous population of Fezf2(+) neurons in both layer 5A and layer 5B of the mature motor cortex. Functional electrophysiology identified two distinct subtypes of Fezf2(+) neurons that resembled pyramidal tract projection neurons (PT-PNs) and intratelencephalic projection neurons (IT-PNs). Retrograde labeling confirmed the former type to include corticospinal projection neurons (CSpPNs) and corticothalamic projection neurons (CThPNs), whereas the latter type included crossed corticostriatal projection neurons (cCStrPNs) and crossed-corticocortical projection neurons (cCCPNs). The two Fezf2(+) subtypes expressed either CTIP2 or SATB2 to distinguish their physiological identity and confirmed that specific expression combinations of key transcription factors persist in the mature motor cortex. Our findings indicate a wider role for Fezf2 within gene expression networks that underpin the diversity of layer 5 cortical projection neurons.

  7. Properties of the primary somatosensory cortex projection to the primary motor cortex in the mouse.

    PubMed

    Petrof, Iraklis; Viaene, Angela N; Sherman, S Murray

    2015-04-01

    The primary somatosensory (S1) and primary motor (M1) cortices are reciprocally connected, and their interaction has long been hypothesized to contribute to coordinated motor output. Very little is known, however, about the nature and synaptic properties of the S1 input to M1. Here we wanted to take advantage of a previously developed sensorimotor slice preparation that preserves much of the S1-to-M1 connectivity (Rocco MM, Brumberg JC. J Neurosci Methods 162: 139-147, 2007), as well as available optogenetic methodologies, in order to investigate the synaptic profile of this projection. Our data show that S1 input to pyramidal cells of M1 is highly homogeneous, possesses many features of a "driver" pathway, such as paired-pulse depression and lack of metabotropic glutamate receptor activation, and is mediated through axons that terminate in both small and large synaptic boutons. Our data suggest that S1 provides M1 with afferents that possess synaptic and anatomical characteristics ideal for the delivery of strong inputs that can "drive" postsynaptic M1 cells, thereby potentially affecting their output.

  8. Somatosensory Cortex Plays an Essential Role in Forelimb Motor Adaptation in Mice.

    PubMed

    Mathis, Mackenzie Weygandt; Mathis, Alexander; Uchida, Naoshige

    2017-03-22

    Our motor outputs are constantly re-calibrated to adapt to systematic perturbations. This motor adaptation is thought to depend on the ability to form a memory of a systematic perturbation, often called an internal model. However, the mechanisms underlying the formation, storage, and expression of such models remain unknown. Here, we developed a mouse model to study forelimb adaptation to force field perturbations. We found that temporally precise photoinhibition of somatosensory cortex (S1) applied concurrently with the force field abolished the ability to update subsequent motor commands needed to reduce motor errors. This S1 photoinhibition did not impair basic motor patterns, post-perturbation completion of the action, or their performance in a reward-based learning task. Moreover, S1 photoinhibition after partial adaptation blocked further adaptation, but did not affect the expression of already-adapted motor commands. Thus, S1 is critically involved in updating the memory about the perturbation that is essential for forelimb motor adaptation.

  9. Changes in sensory hand representation and pain thresholds induced by motor cortex stimulation in humans.

    PubMed

    Houzé, Bérengère; Bradley, Claire; Magnin, Michel; Garcia-Larrea, Luis

    2013-11-01

    Shrinking of deafferented somatosensory regions after neural damage is thought to participate to the emergence of neuropathic pain, and pain-relieving procedures have been reported to induce the normalization of altered cortical maps. While repetitive magnetic stimulation (rTMS) of the motor cortex can lessen neuropathic pain, no evidence has been provided that this is concomitant to changes in sensory maps. Here, we assessed in healthy volunteers the ability of 2 modes of motor cortex rTMS commonly used in pain patients to induce changes in pain thresholds and plastic phenomena in the S1 cortex. Twenty minutes of high-frequency (20 Hz) rTMS significantly increased pain thresholds in the contralateral hand, and this was associated with the expansion of the cortical representation of the hand on high-density electroencephalogram source analysis. Neither of these effects were observed after sham rTMS, nor following intermittent theta-burst stimulation (iTBS). The superiority of 20-Hz rTMS over iTBS to induce sensory plasticity may reflect its better match with intrinsic cortical motor frequencies, which oscillate at around 20 Hz. rTMS-induced changes might partly counterbalance the plasticity induced by a nerve lesion, and thus substantiate the use of rTMS to treat human pain. However, a mechanistic relation between S1 plasticity and pain-relieving effects is far from being established.

  10. Functional clustering of neurons in motor cortex determined by cellular resolution imaging in awake behaving mice

    PubMed Central

    Dombeck, Daniel A.; Graziano, Michael S.; Tank, David W.

    2010-01-01

    Macroscopic (millimeter scale) functional clustering is a hallmark characteristic of motor cortex spatial organization in awake behaving mammals; however, almost no information is known about the functional micro-organization (~100 microns scale). Here, we optically recorded intracellular calcium transients of layer 2/3 neurons with cellular resolution over ~200 micron diameter fields in the forelimb motor cortex of mobile, head-restrained mice during two distinct movements (running and grooming). We showed that the temporal correlation between neurons was statistically larger the closer the neurons were to each other. We further explored this correlation by using two separate methods to spatially segment the neurons within each imaging field: K-means clustering and correlations between single neuron activity and mouse movements. The two methods segmented the neurons similarly and led to the conclusion that the origin of the inverse relationship between correlation and distance seen statistically was two-fold: clusters of highly temporally correlated neurons were often spatially distinct from one another and (even when the clusters were spatially intermingled) within the clusters, the more correlated the neurons were to each other, the shorter the distance between them. Our results represent a direct observation of functional clustering within the micro-circuitry of the awake mouse motor cortex. PMID:19889987

  11. Physical activity-associated gene expression signature in nonhuman primate motor cortex.

    PubMed

    Mitchell, Amanda C; Leak, Rehana K; Garbett, Krassimira; Zigmond, Michael J; Cameron, Judy L; Mirnics, Károly

    2012-03-01

    It has been established that weight gain and weight loss are heavily influenced by activity level. In this study, we hypothesized that the motor cortex exhibits a distinct physical activity-associated gene expression profile, which may underlie changes in weight associated with movement. Using DNA microarrays we profiled gene expression in the motor cortex of a group of 14 female rhesus monkeys (Macaca mulatta) with a wide range of stable physical activity levels. We found that neuronal growth factor signaling and nutrient sensing transcripts in the brain were highly correlated with physical activity. A follow-up of AKT3 expression changes (a gene at the apex of neuronal survival and nutrient sensing) revealed increased protein levels of total AKT, phosphorylated AKT, and forkhead box O3 (FOXO3), one of AKT's main downstream effectors. In addition, we successfully validated three other genes via quantitative polymerase chain reaction (qPCR) (cereblon (CRBN), origin recognition complex subunit 4-like, and pyruvate dehydrogenase 4 (PDK4)). We conclude that these genes are important in the physical activity-associated pathway in the motor cortex, and may be critical for physical activity-associated changes in body weight and neuroprotection.

  12. Cortical current density oscillations in the motor cortex are correlated with muscular activity during pedaling exercise.

    PubMed

    Schneider, S; Rouffet, D M; Billaut, F; Strüder, H K

    2013-01-03

    Despite modern imaging techniques, assessing and localizing changes in brain activity during whole-body exercise is still challenging. Using an active electroencephalography (EEG) system in combination with source localization algorithms, this study aimed to localize brain cortical oscillations patterns in the motor cortex and to correlate these with surface electromyography (EMG)-detected muscular activity during pedaling exercise. Eight subjects performed 2-min isokinetic (90 rpm) cycling bouts at intensities ranging from 1 to 5 Wkg(-1) body mass on a cycle ergometer. These bouts were interspersed by a minimum of 2 min of passive rest to limit to development of peripheral muscle fatigue. Brain cortical activity within the motor cortex was analyzed using a 32-channel active EEG system combined with source localization algorithms. EMG activity was recorded from seven muscles on each lower limb. EEG and EMG activity revealed comparatively stable oscillations across the different exercise intensities. More importantly, the oscillations in cortical activity within the motor cortex were significantly correlated with EMG activity during the high-intensity cycling bouts. This study demonstrates that it is possible to localize oscillations in brain cortical activity during moderate- to high-intensity cycling exercise using EEG in combination with source localization algorithms, and that these oscillations match the activity of the active muscles in time and amplitude. Results of this study might help to further evaluate the effects of central vs. peripheral fatigue during exercise.

  13. Motor cortex stimulation reduces hyperalgesia in an animal model of central pain.

    PubMed

    Lucas, Jessica M; Ji, Yadong; Masri, Radi

    2011-06-01

    Electrical stimulation of the primary motor cortex has been used since 1991 to treat chronic neuropathic pain. Since its inception, motor cortex stimulation (MCS) treatment has had varied clinical outcomes. Until this point, there has not been a systematic study of the stimulation parameters that most effectively treat chronic pain, or of the mechanisms by which MCS relieves pain. Here, using a rodent model of central pain, we perform a systematic study of stimulation parameters used for MCS and investigate the mechanisms by which MCS reduces hyperalgesia. Specifically, we study the role of the inhibitory nucleus zona incerta (ZI) in mediating the analgesic effects of MCS. In animals with mechanical and thermal hyperalgesia, we find that stimulation at 50 μA, 50 Hz, and 300 μs square pulses for 30 minutes is sufficient to reverse mechanical and thermal hyperalgesia. We also find that stimulation of the ZI mimics the effects of MCS and that reversible inactivation of ZI blocks the effects of MCS. These findings suggest that the reduction of hyperalgesia may be due to MCS effects on ZI. In an animal model of central pain syndrome, motor cortex stimulation reduces hyperalgesia by activating zona incerta and therefore restoring inhibition in the thalamus.

  14. Age-related decline in the responsiveness of motor cortex to plastic forces reverses with levodopa or cerebellar stimulation.

    PubMed

    Kishore, Asha; Popa, Traian; James, Praveen; Yahia-Cherif, Lydia; Backer, Febina; Varughese Chacko, Lijo; Govind, Preetha; Pradeep, Salini; Meunier, Sabine

    2014-11-01

    The plasticity of motor cortex is integral for motor memory and skills acquisition but it declines with aging. Forty healthy volunteers, across 6 decades, were tested to examine the (a) age-dependency of motor cortex responsiveness to plasticity induction, as measured from the response to paired associative stimulation (PAS) and the (b) effect of aging on the cerebellar modulation of motor cortex response to PAS. We examined if reduced dopaminergic transmission was involved in the age-related decline of response to PAS by retesting 10 of the older subjects after a single dose of levodopa. There was a substantial decline in the motor cortex response to PAS with aging, which was restored by levodopa in the older subjects. The cerebellar modulation of motor cortex response to PAS was less vulnerable to aging and a single session of cerebellar inhibition reinstated the cortical responsiveness in older subjects. Both levodopa and cerebellar inhibition can be tested for their ability to enhance motor skills acquisition and motor performance in the elderly individuals.

  15. An Investigation of Cholinergic Circuitry in Cat Striate Cortex Using Acetylcholinesterase Histochemistry.

    DTIC Science & Technology

    1984-10-10

    experience of the kitten , the suggestion has been made that they are the neural substrate of a form of learning and memory (Spinelli and Jensen, 1979...enzymes, especially AChE, show provocative changes in kitten striate cortex during the critical period when area 17 is modifiable by the visual...Singer (1982) has found that lesions of the intralaminar thalamus will abolish the normal response of kitten striate cortex to extended periods of

  16. Disruption of functional organization within the primary motor cortex in children with autism.

    PubMed

    Nebel, Mary Beth; Joel, Suresh E; Muschelli, John; Barber, Anita D; Caffo, Brian S; Pekar, James J; Mostofsky, Stewart H

    2014-02-01

    Accumulating evidence suggests that motor impairments are prevalent in autism spectrum disorder (ASD), relate to the social and communicative deficits at the core of the diagnosis and may reflect abnormal connectivity within brain networks underlying motor control and learning. Parcellation of resting-state functional connectivity data using spectral clustering approaches has been shown to be an effective means of visualizing functional organization within the brain but has most commonly been applied to explorations of normal brain function. This article presents a parcellation of a key area of the motor network, the primary motor cortex (M1), a key area of the motor control network, in adults, typically developing (TD) children and children with ASD and introduces methods for selecting the number of parcels, matching parcels across groups and testing group differences. The parcellation is based solely on patterns of connectivity between individual M1 voxels and all voxels outside of M1, and within all groups, a gross dorsomedial to ventrolateral organization emerged within M1 which was left-right symmetric. Although this gross organizational scheme was present in both groups of children, statistically significant group differences in the size and segregation of M1 parcels within regions of the motor homunculus corresponding to the upper and lower limbs were observed. Qualitative comparison of the M1 parcellation for children with ASD with that of younger and older TD children suggests that these organizational differences, with a lack of differentiation between lower limb/trunk regions and upper limb/hand regions, may be due, at least in part, to a delay in functional specialization within the motor cortex.

  17. Functional connectivity of primary motor cortex is dependent on genetic burden in prodromal Huntington disease.

    PubMed

    Koenig, Katherine A; Lowe, Mark J; Harrington, Deborah L; Lin, Jian; Durgerian, Sally; Mourany, Lyla; Paulsen, Jane S; Rao, Stephen M

    2014-09-01

    Subtle changes in motor function have been observed in individuals with prodromal Huntington disease (prHD), but the underlying neural mechanisms are not well understood nor is the cumulative effect of the disease (disease burden) on functional connectivity. The present study examined the resting-state functional magnetic resonance imaging (rs-fMRI) connectivity of the primary motor cortex (M1) in 16 gene-negative (NEG) controls and 48 gene-positive prHD participants with various levels of disease burden. The results showed that the strength of the left M1 connectivity with the ipsilateral M1 and somatosensory areas decreased as disease burden increased and correlated with motor symptoms. Weakened M1 connectivity within the motor areas was also associated with abnormalities in long-range connections that evolved with disease burden. In this study, M1 connectivity was decreased with visual centers (bilateral cuneus), but increased with a hub of the default mode network (DMN; posterior cingulate cortex). Changes in connectivity measures were associated with worse performance on measures of cognitive-motor functioning. Short- and long-range functional connectivity disturbances were also associated with volume loss in the basal ganglia, suggesting that weakened M1 connectivity is partly a manifestation of striatal atrophy. Altogether, the results indicate that the prodromal phase of HD is associated with abnormal interhemispheric interactions among motor areas and disturbances in the connectivity of M1 with visual centers and the DMN. These changes may, respectively, contribute to increased motor symptoms, visuomotor integration problems, and deficits in the executive control of movement as individuals approach a manifest diagnosis.

  18. Functional Connectivity of Primary Motor Cortex Is Dependent on Genetic Burden in Prodromal Huntington Disease

    PubMed Central

    Koenig, Katherine A.; Lowe, Mark J.; Harrington, Deborah L.; Lin, Jian; Durgerian, Sally; Mourany, Lyla; Paulsen, Jane S.

    2014-01-01

    Abstract Subtle changes in motor function have been observed in individuals with prodromal Huntington disease (prHD), but the underlying neural mechanisms are not well understood nor is the cumulative effect of the disease (disease burden) on functional connectivity. The present study examined the resting-state functional magnetic resonance imaging (rs-fMRI) connectivity of the primary motor cortex (M1) in 16 gene-negative (NEG) controls and 48 gene-positive prHD participants with various levels of disease burden. The results showed that the strength of the left M1 connectivity with the ipsilateral M1 and somatosensory areas decreased as disease burden increased and correlated with motor symptoms. Weakened M1 connectivity within the motor areas was also associated with abnormalities in long-range connections that evolved with disease burden. In this study, M1 connectivity was decreased with visual centers (bilateral cuneus), but increased with a hub of the default mode network (DMN; posterior cingulate cortex). Changes in connectivity measures were associated with worse performance on measures of cognitive–motor functioning. Short- and long-range functional connectivity disturbances were also associated with volume loss in the basal ganglia, suggesting that weakened M1 connectivity is partly a manifestation of striatal atrophy. Altogether, the results indicate that the prodromal phase of HD is associated with abnormal interhemispheric interactions among motor areas and disturbances in the connectivity of M1 with visual centers and the DMN. These changes may, respectively, contribute to increased motor symptoms, visuomotor integration problems, and deficits in the executive control of movement as individuals approach a manifest diagnosis. PMID:25072408

  19. Primary Motor Cortex Representation of Handgrip Muscles in Patients with Leprosy

    PubMed Central

    Rangel, Maria Luíza Sales; Sanchez, Tiago Arruda; Moreira, Filipe Azaline; Hoefle, Sebastian; Souto, Inaiacy Bittencourt; da Cunha, Antônio José Ledo Alves

    2015-01-01

    Background Leprosy is an endemic infectious disease caused by Mycobacterium leprae that predominantly attacks the skin and peripheral nerves, leading to progressive impairment of motor, sensory and autonomic function. Little is known about how this peripheral neuropathy affects corticospinal excitability of handgrip muscles. Our purpose was to explore the motor cortex organization after progressive peripheral nerve injury and upper-limb dysfunction induced by leprosy using noninvasive transcranial magnetic stimulation (TMS). Methods In a cross-sectional study design, we mapped bilaterally in the primary motor cortex (M1) the representations of the hand flexor digitorum superficialis (FDS), as well as of the intrinsic hand muscles abductor pollicis brevis (APB), first dorsal interosseous (FDI) and abductor digiti minimi (ADM). All participants underwent clinical assessment, handgrip dynamometry and motor and sensory nerve conduction exams 30 days before mapping. Wilcoxon signed rank and Mann-Whitney tests were performed with an alpha-value of p<0.05. Findings Dynamometry performance of the patients’ most affected hand (MAH), was worse than that of the less affected hand (LAH) and of healthy controls participants (p = 0.031), confirming handgrip impairment. Motor threshold (MT) of the FDS muscle was higher in both hemispheres in patients as compared to controls, and lower in the hemisphere contralateral to the MAH when compared to that of the LAH. Moreover, motor evoked potential (MEP) amplitudes collected in the FDS of the MAH were higher in comparison to those of controls. Strikingly, MEPs in the intrinsic hand muscle FDI had lower amplitudes in the hemisphere contralateral to MAH as compared to those of the LAH and the control group. Taken together, these results are suggestive of a more robust representation of an extrinsic hand flexor and impaired intrinsic hand muscle function in the hemisphere contralateral to the MAH due to leprosy. Conclusion Decreased

  20. Bilateral primary motor cortex circuitry is modulated due to theta burst stimulation to left dorsal premotor cortex and bimanual training.

    PubMed

    Neva, Jason L; Vesia, Michael; Singh, Amaya M; Staines, W Richard

    2015-08-27

    Motor preparatory and execution activity is enhanced after a single session of bimanual visuomotor training (BMT). Recently, we have shown that increased primary motor cortex (M1) excitability occurs when BMT involves simultaneous activation of homologous muscles and these effects are enhanced when BMT is preceded by intermittent theta burst stimulation (iTBS) to the left dorsal premotor cortex (lPMd). The neural mechanisms underlying these modulations are unclear, but may include interhemispheric interactions between homologous M1s and connectivity with premotor regions. The purpose of this study was to investigate the possible intracortical and interhemispheric modulations of the extensor carpi radials (ECR) representation in M1 bilaterally due to: (1) BMT, (2) iTBS to lPMd, and (3) iTBS to lPMd followed by BMT. This study tests three related hypotheses: (1) BMT will enhance excitability within and between M1 bilaterally, (2) iTBS to lPMd will primarily enhance left M1 (lM1) excitability, and (3) the combination of these interventions will cause a greater enhancement of bilateral M1 excitability. We used single and paired-pulse transcranial magnetic stimulation (TMS) to quantify M1 circuitry bilaterally. The results demonstrate the neural mechanisms underlying the early markers of rapid functional plasticity associated with BMT and iTBS to lPMd primarily relate to modulations of long-interval inhibitory (i.e. GABAB-mediated) circuitry within and between M1s. This work provides novel insight into the underlying neural mechanisms involved in M1 excitability changes associated with BMT and iTBS to lPMd. Critically, this work may inform rehabilitation training and stimulation techniques that modulate cortical plasticity after brain injury.

  1. Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter.

    PubMed

    Neef, Nicole E; Hoang, T N Linh; Neef, Andreas; Paulus, Walter; Sommer, Martin

    2015-03-01

    The precise excitability regulation of neuronal circuits in the primary motor cortex is central to the successful and fluent production of speech. Our question was whether the involuntary execution of undesirable movements, e.g. stuttering, is linked to an insufficient excitability tuning of neural populations in the orofacial region of the primary motor cortex. We determined the speech-related time course of excitability modulation in the left and right primary motor tongue representation. Thirteen fluent speakers (four females, nine males; aged 23-44) and 13 adults who stutter (four females, nine males, aged 21-55) were asked to build verbs with the verbal prefix 'auf'. Single-pulse transcranial magnetic stimulation was applied over the primary motor cortex during the transition phase between a fixed labiodental articulatory configuration and immediately following articulatory configurations, at different latencies after transition onset. Bilateral electromyography was recorded from self-adhesive electrodes placed on the surface of the tongue. Off-line, we extracted the motor evoked potential amplitudes and normalized these amplitudes to the individual baseline excitability during the fixed configuration. Fluent speakers demonstrated a prominent left hemisphere increase of motor cortex excitability in the transition phase (P = 0.009). In contrast, the excitability of the right primary motor tongue representation was unchanged. Interestingly, adults afflicted with stuttering revealed a lack of left-hemisphere facilitation. Moreover, the magnitude of facilitation was negatively correlated with stuttering frequency. Although orofacial midline muscles are bilaterally innervated from corticobulbar projections of both hemispheres, our results indicate that speech motor plans are controlled primarily in the left primary speech motor cortex. This speech motor planning-related asymmetry towards the left orofacial motor cortex is missing in stuttering. Moreover, a negative

  2. Speech dynamics are coded in the left motor cortex in fluent speakers but not in adults who stutter

    PubMed Central

    Hoang, T. N. Linh; Neef, Andreas; Paulus, Walter; Sommer, Martin

    2015-01-01

    The precise excitability regulation of neuronal circuits in the primary motor cortex is central to the successful and fluent production of speech. Our question was whether the involuntary execution of undesirable movements, e.g. stuttering, is linked to an insufficient excitability tuning of neural populations in the orofacial region of the primary motor cortex. We determined the speech-related time course of excitability modulation in the left and right primary motor tongue representation. Thirteen fluent speakers (four females, nine males; aged 23–44) and 13 adults who stutter (four females, nine males, aged 21–55) were asked to build verbs with the verbal prefix ‘auf’. Single-pulse transcranial magnetic stimulation was applied over the primary motor cortex during the transition phase between a fixed labiodental articulatory configuration and immediately following articulatory configurations, at different latencies after transition onset. Bilateral electromyography was recorded from self-adhesive electrodes placed on the surface of the tongue. Off-line, we extracted the motor evoked potential amplitudes and normalized these amplitudes to the individual baseline excitability during the fixed configuration. Fluent speakers demonstrated a prominent left hemisphere increase of motor cortex excitability in the transition phase (P = 0.009). In contrast, the excitability of the right primary motor tongue representation was unchanged. Interestingly, adults afflicted with stuttering revealed a lack of left-hemisphere facilitation. Moreover, the magnitude of facilitation was negatively correlated with stuttering frequency. Although orofacial midline muscles are bilaterally innervated from corticobulbar projections of both hemispheres, our results indicate that speech motor plans are controlled primarily in the left primary speech motor cortex. This speech motor planning-related asymmetry towards the left orofacial motor cortex is missing in stuttering. Moreover, a

  3. Acute effects of alcohol on unit activity in the motor cortex of freely moving rabbits: comparison with the limbic cortex.

    PubMed

    Alexandrov, Y I; Grinchenko, Y V; Laukka, S; Järvilehto, T; Maz, V N

    1991-07-01

    Unit activity was recorded from the motor cortex of eight freely moving rabbits in order to examine the acute effect of ethanol (1 g kg-1) on organization of unit activity and to compare it with our earlier results from the limbic cortex. The rabbits performed a food-acquisition task in the experimental cage. Unit activity was recorded during behaviour in the control experiment followed by the alcohol experiment on the next day. After ethanol, behavioural mistakes and the duration of the behavioural cycle significantly increased. In the control experiments activation of 58% of the units had no constant relation to the phases of the behavioural cycle (non-involved units), whereas 42% of the units were constantly activated during certain phases (involved units). Two per cent of the latter units were activated in relation to newly learned behavioural acts (e.g. pedal pressing; L units), 28% in relation to food seizure and/or grinding (S units) and 12% in relation to certain movements during different behavioural acts (M units). Ethanol had no effect on the number of active units and the same relation between the number of non-involved and involved units or between the number of different types of involved units was found. However, the number of involved units decreased in the upper and increased in the lower cortical layers. Also the number of units with low background frequency increased, although the frequency within activations did not change. In our earlier study the number of active units in the limbic cortex decreased after ethanol by one third and the relation between the number of L and M units was reversed.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex

    PubMed Central

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2017-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices. PMID:28101014

  5. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex.

    PubMed

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2016-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices.

  6. Pathways and genes differentially expressed in the motor cortex of patients with sporadic amyotrophic lateral sclerosis

    PubMed Central

    Lederer, Carsten W; Torrisi, Antonietta; Pantelidou, Maria; Santama, Niovi; Cavallaro, Sebastiano

    2007-01-01

    Background Amyotrophic lateral sclerosis (ALS) is a fatal disorder caused by the progressive degeneration of motoneurons in brain and spinal cord. Despite identification of disease-linked mutations, the diversity of processes involved and the ambiguity of their relative importance in ALS pathogenesis still represent a major impediment to disease models as a basis for effective therapies. Moreover, the human motor cortex, although critical to ALS pathology and physiologically altered in most forms of the disease, has not been screened systematically for therapeutic targets. Results By whole-genome expression profiling and stringent significance tests we identify genes and gene groups de-regulated in the motor cortex of patients with sporadic ALS, and interpret the role of individual candidate genes in a framework of differentially expressed pathways. Our findings emphasize the importance of defense responses and cytoskeletal, mitochondrial and proteasomal dysfunction, reflect reduced neuronal maintenance and vesicle trafficking, and implicate impaired ion homeostasis and glycolysis in ALS pathogenesis. Additionally, we compared our dataset with publicly available data for the SALS spinal cord, and show a high correlation of changes linked to the diseased state in the SALS motor cortex. In an analogous comparison with data for the Alzheimer's disease hippocampus we demonstrate a low correlation of global changes and a moderate correlation for changes specifically linked to the SALS diseased state. Conclusion Gene and sample numbers investigated allow pathway- and gene-based analyses by established error-correction methods, drawing a molecular portrait of the ALS motor cortex that faithfully represents many known disease features and uncovers several novel aspects of ALS pathology. Contrary to expectations for a tissue under oxidative stress, nuclear-encoded mitochondrial genes are uniformly down-regulated. Moreover, the down-regulation of mitochondrial and glycolytic

  7. [Motor cortex stimulation for post-stroke pain using neuronavigation and evoked potentials: report of 3 cases].

    PubMed

    Ito, Masaki; Kuroda, Satoshi; Takano, Kazuya; Maruichi, Katsuhiko; Chiba, Yasuhiro; Morimoto, Yuji; Iwasaki, Yoshinobu

    2006-09-01

    Although motor cortex stimulation (MCS) has been accepted as an effective therapeutic option for central pain, the efficacy of MCS widely varies among previous reports. In this report, we describe our recent trial for successful MCS in 3 patients with central pain due to cerebral stroke. Medical treatments were transiently effective, but gradually became ineffective in all of the cases. During surgery, the appropriate cortical target was determined by using neuronavigation, somatosensory evoked potential (SEP), and motor evoked potential (MEP). A flat, four-plate electrode was positioned on the dura mater parallel to the motor cortex. After surgery, pain almost resolved in 2 of 3 patients and markedly improved in another. The pain relief depended on their motor function. These findings strongly suggest that both patient selection and intraoperative monitoring for targeting the motor cortex are quite important for successful MCS, although further studies were essential.

  8. Mechanisms of human motor cortex facilitation induced by subthreshold 5-Hz repetitive transcranial magnetic stimulation.

    PubMed

    Sommer, Martin; Rummel, Milena; Norden, Christoph; Rothkegel, Holger; Lang, Nicolas; Paulus, Walter

    2013-06-01

    Our knowledge about the mechanisms of human motor cortex facilitation induced by repetitive transcranial magnetic stimulation (rTMS) is still incomplete. Here we used pharmacological conditioning with carbamazepine, dextrometorphan, lorazepam, and placebo to elucidate the type of plasticity underlying this facilitation, and to probe if mechanisms reminiscent of long-term potentiation are involved. Over the primary motor cortex of 10 healthy subjects, we applied biphasic rTMS pulses of effective posterior current direction in the brain. We used six blocks of 200 pulses at 5-Hz frequency and 90% active motor threshold intensity and controlled for corticospinal excitability changes using motor-evoked potential (MEP) amplitudes and latencies elicited by suprathreshold pulses before, in between, and after rTMS. Target muscle was the dominant abductor digiti minimi muscle; we coregistered the dominant extensor carpi radialis muscle. We found a lasting facilitation induced by this type of rTMS. The GABAergic medication lorazepam and to a lesser extent the ion channel blocker carbamazepine reduced the MEP facilitation after biphasic effective posteriorly oriented rTMS, whereas the N-methyl-d-aspartate receptor-antagonist dextrometorphan had no effect. Our main conclusion is that the mechanism of the facilitation induced by biphasic effective posterior rTMS is more likely posttetanic potentiation than long-term potentiation. Additional findings were prolonged MEP latency under carbamazepine, consistent with sodium channel blockade, and larger MEP amplitudes from extensor carpi radialis under lorazepam, suggesting GABAergic involvement in the center-surround balance of excitability.

  9. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    PubMed

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  10. Intrahemispheric dysfunction in primary motor cortex without corpus callosum: a transcranial magnetic stimulation study

    PubMed Central

    Fecteau, Shirley; Lassonde, Maryse; Théoret, Hugo

    2006-01-01

    Background The two human cerebral hemispheres are continuously interacting, through excitatory and inhibitory influences and one critical structure subserving this interhemispheric balance is the corpus callosum. Interhemispheric neurophysiological abnormalities and intrahemispheric behavioral impairments have been reported in individuals lacking the corpus callosum. The aim of this study was to examine intrahemispheric neurophysiological function in primary motor cortex devoid of callosal projections. Methods Intracortical excitatory and inhibitory systems were tested in three individuals with complete agenesis of the corpus callosum and sixteen healthy individuals. These systems were assessed using transcranial magnetic stimulation (TMS) protocols: motor threshold at rest, paired-pulse curve, and cortical silent period. Results TMS revealed no difference between the patient and control groups on the motor threshold measure, as well as intracortical facilitation and intracortical inhibition systems as tested by paired stimulation. However, intrahemispheric inhibitory function was found to be abnormal in participants without callosal projections, as the cortical silent period duration was significantly increased in the patient group. Conclusion These data suggest that in addition to previously reported impaired interhemispheric function, patients lacking the entire corpus callosum also display abnormal intrahemispheric excitability of the primary motor cortex. PMID:16790050

  11. Spinal cord injury affects I-wave facilitation in human motor cortex.

    PubMed

    Nardone, Raffaele; Höller, Yvonne; Bathke, Arne C; Orioli, Andrea; Schwenker, Kerstin; Frey, Vanessa; Golaszewski, Stefan; Brigo, Francesco; Trinka, Eugen

    2015-07-01

    Transcranial magnetic stimulation (TMS) is a useful non-invasive approach for studying cortical physiology. To further clarify the mechanisms of cortical reorganization after spinal cord injury (SCI), we used a non-invasive paired TMS protocol for the investigation of the corticospinal I-waves, the so-called I-wave facilitation, in eight patients with cervical SCI. We found that the pattern of I-wave facilitation significantly differs between SCI patients with normal and abnormal central motor conduction (CMCT), and healthy controls. The group with normal CMCT showed increased I-wave facilitation, while the group with abnormal CMCT showed lower I-wave facilitation compared to a control group. The facilitatory I-wave interaction occurs at the level of the motor cortex, and the mechanisms responsible for the production of I-waves are under control of GABA-related inhibition. Therefore, the findings of our small sample preliminary study provide further physiological evidence of increased motor cortical excitability in patients with preserved corticospinal projections. This is possibly due to decreased GABAergic intracortical inhibition. The excitability of networks producing short-interval intracortical facilitation could increase after SCI as a mechanism to enhance activation of residual corticospinal tract pathways and thus compensate for the impaired ability of the motor cortex to generate appropriate voluntary movements. Finally, the I-wave facilitation technique could be used in clinical neurorehabilitation as an additional method of assessing and monitoring function in SCI.

  12. Interhemispheric visuo-motor integration in humans: the role of the superior parietal cortex.

    PubMed

    Iacoboni, Marco; Zaidel, Eran

    2004-01-01

    We used event-related functional magnetic resonance imaging (fMRI) to investigate the neural correlates of basic interhemispheric visuo-motor integration. In a simple reaction time task, subjects responded to lateralized left and right light flashes with unimanual left and right hand responses. Typically, reaction times are faster for uncrossed responses (that is, visual stimulus and response hand on the same side) than for crossed responses (that is, visual stimulus and response hand on opposite sides). The chronometric difference between crossed and uncrossed responses is called crossed-uncrossed difference (CUD) and it is typically taken to represent a behavioral estimate of interhemispheric transfer time. The fMRI results obtained in normal right-handers show that the crossed conditions yielded greater activity, compared to the uncrossed conditions, in bilateral prefrontal, bilateral dorsal premotor, and right superior parietal areas. These results suggest that multiple transfers between the hemispheres occur in parallel at the functional levels of sensory-motor integration (posterior parietal), decision-making (prefrontal) and preparation of motor response (premotor). To test the behavioral significance of these multiple transfers, we correlated the individual CUDs with the difference in signal intensity between crossed and uncrossed responses in the prefrontal, dorsal premotor, and right superior parietal activated areas. The analyses demonstrated a strong correlation between the CUD and signal intensity difference between crossed and uncrossed responses in the right superior parietal cortex. These data suggest a critical role of the superior parietal cortex in interhemispheric visuo-motor integration.

  13. Reorganization in the ipsilateral motor cortex of patients with lower limb amputation.

    PubMed

    Schwenkreis, Peter; Pleger, Burkhard; Cornelius, Beate; Weyen, Ute; Dertwinkel, Roman; Zenz, Michael; Malin, Jean Pierre; Tegenthoff, Martin

    2003-10-09

    The aim of the present study was to assess reorganization in the motor cortex of patients with lower limb amputation. We studied seven patients with traumatic lower limb amputation, and six healthy controls, using transcranial magnetic stimulation mapping, with recordings from the quadriceps femoris muscle on both sides. Motor threshold, sum of amplitudes, area and the amplitude-weighted centre of gravity (COG) of the motor output map were assessed. We found a significant lateral displacement of the COG on the hemisphere contralateral to the healthy leg, whereas other parameters did not differ significantly between sides. This finding might be indicative of cortical reorganization in the hemisphere ipsilateral to the amputation. It is discussed with respect to an altered peripheral input to this hemisphere, and to transcallosal interactions from the deafferented hemisphere.

  14. A Causal Role for Primary Motor Cortex in Perception of Observed Actions

    PubMed Central

    Palmer, Clare E.; Bunday, Karen L.; Davare, Marco; Kilner, James M.

    2017-01-01

    It has been proposed that motor system activity during action observation may be modulated by the kinematics of observed actions. One purpose of this activity during action observation may be to predict the visual consequence of another person’s action based on their movement kinematics. Here, we tested the hypothesis that the primary motor cortex (M1) may have a causal role in inferring information that is present in the kinematics of observed actions. Healthy participants completed an action perception task before and after applying continuous theta burst stimulation (cTBS) over left M1. A neurophysiological marker was used to quantify the extent of M1 disruption following cTBS and stratify our sample a priori to provide an internal control. We found that a disruption to M1 caused a reduction in an individual’s sensitivity to interpret the kinematics of observed actions; the magnitude of suppression of motor excitability predicted this change in sensitivity. PMID:27458752

  15. Modulation of motor cortex neuronal activity and motor behavior during subthalamic nucleus stimulation in the normal primate.

    PubMed

    Johnson, Luke A; Xu, Weidong; Baker, Kenneth B; Zhang, Jianyu; Vitek, Jerrold L

    2015-04-01

    Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a well-established surgical therapy for advanced Parkinson's disease (PD). An emerging hypothesis is that the therapeutic benefit of DBS is derived from direct modulation of primary motor cortex (M1), yet little is known about the influence of STN DBS on individual neurons in M1. We investigated the effect of STN DBS, delivered at discrete interval intensities (20, 40, 60, 80, and 100%) of corticospinal tract threshold (CSTT), on motor performance and M1 neuronal activity in a naive nonhuman primate. Motor performance during a food reach and retrieval task improved during low-intensity stimulation (20% CSTT) but worsened as intensity approached the threshold for activation of corticospinal fibers (80% and 100% CSTT). To assess cortical effects of STN DBS, spontaneous, extracellular neuronal activity was collected from M1 neurons before, during, and after DBS at the same CSTT stimulus intensities. STN DBS significantly modulated the firing of a majority of M1 neurons; however, the direction of effect varied with stimulus intensity such that, at 20% CSTT, most neurons were suppressed, whereas at the highest stimulus intensities the majority of neurons were activated. At a population level, firing rates increased as stimulus intensity increased. These results show that STN DBS influences both motor performance and M1 neuronal activity systematically according to stimulus intensity. In addition, the unanticipated reduction in reach times suggests that STN DBS, at stimulus intensities lower than typically used for treatment of PD motor signs, can enhance normal motor performance.

  16. Melodic Priming of Motor Sequence Performance: The Role of the Dorsal Premotor Cortex

    PubMed Central

    Stephan, Marianne A.; Brown, Rachel; Lega, Carlotta; Penhune, Virginia

    2016-01-01

    The purpose of this study was to determine whether exposure to specific auditory sequences leads to the induction of new motor memories and to investigate the role of the dorsal premotor cortex (dPMC) in this crossmodal learning process. Fifty-two young healthy non-musicians were familiarized with the sound to key-press mapping on a computer keyboard and tested on their baseline motor performance. Each participant received subsequently either continuous theta burst stimulation (cTBS) or sham stimulation over the dPMC and was then asked to remember a 12-note melody without moving. For half of the participants, the contour of the melody memorized was congruent to a subsequently performed, but never practiced, finger movement sequence (Congruent group). For the other half, the melody memorized was incongruent to the subsequent finger movement sequence (Incongruent group). Hearing a congruent melody led to significantly faster performance of a motor sequence immediately thereafter compared to hearing an incongruent melody. In addition, cTBS speeded up motor performance in both groups, possibly by relieving motor consolidation from interference by the declarative melody memorization task. Our findings substantiate recent evidence that exposure to a movement-related tone sequence can induce specific, crossmodal encoding of a movement sequence representation. They further suggest that cTBS over the dPMC may enhance early offline procedural motor skill consolidation in cognitive states where motor consolidation would normally be disturbed by concurrent declarative memory processes. These findings may contribute to a better understanding of auditory-motor system interactions and have implications for the development of new motor rehabilitation approaches using sound and non-invasive brain stimulation as neuromodulatory tools. PMID:27242414

  17. A fibronectin-like molecule is present in the developing cat cerebral cortex and is correlated with subplate neurons

    PubMed Central

    1988-01-01

    The subplate is a transient zone of the developing cerebral cortex through which postmitotic neurons migrate and growing axons elongate en route to their adult positions within the cortical plate. To learn more about the cellular interactions that occur in this zone, we have examined whether fibronectins (FNs), a family of molecules known to promote migration and elongation in other systems, are present during the fetal and postnatal development of the cat's cerebral cortex. Three different anti-FN antisera recognized a single broad band with an apparent molecular mass of 200-250 kD in antigen-transfer analyses (reducing conditions) of plasma-depleted (perfused) whole fetal brain or synaptosome preparations, indicating that FNs are present at these ages. This band can be detected as early as 1 mo before birth at embryonic day 39. Immunohistochemical examination of the developing cerebral cortex from animals between embryonic day 46 and postnatal day 7 using any of the three antisera revealed that FN-like immunoreactivity is restricted to the subplate and the marginal zones, and is not found in the cortical plate. As these zones mature into their adult counterparts (the white matter and layer 1 of the cerebral cortex), immunostaining gradually disappears and is not detectable by postnatal day 70. Previous studies have shown that the subplate and marginal zones contain a special, transient population of neurons (Chun, J. J. M., M. J. Nakamura, and C. J. Shatz. 1987. Nature (Lond.). 325:617-620). The FN-like immunostaining in the subplate and marginal zone is closely associated with these neurons, and some of the immunostaining delineates them. Moreover, the postnatal disappearance of FN-like immunostaining from the subplate is correlated spatially and temporally with the disappearance of the subplate neurons. When subplate neurons are killed by neurotoxins, FN-like immunostaining is depleted in the lesioned area. These observations show that an FN-like molecule is

  18. Influence of repetitive peripheral magnetic stimulation on neural plasticity in the motor cortex related to swallowing.

    PubMed

    Momosaki, Ryo; Kakuda, Wataru; Yamada, Naoki; Abo, Masahiro

    2016-09-01

    The aim of this study was to evaluate the effect of repetitive peripheral magnetic stimulation at two different frequencies (20 and 30 Hz) on cortical excitability in motor areas related to swallowing in healthy individuals. The study participants were 10 healthy normal volunteers (two women and eight men, age range 25-36 years). Repetitive peripheral magnetic stimulation was applied to the submandibular muscle using a parabolic coil at the site where contraction of the suprahyoid muscles was elicited. Stimulation was continued for 10 min (total 1200 pulses) at 20 Hz on 1 day and at 30 Hz on another day, with the stimulation strength set at 90% of the intensity that elicited pain. The motor-evoked potential amplitude of suprahyoid muscles was assessed before, immediately after, and 30 min after stimulation. Stimulations at both 20 and 30 Hz significantly increased motor-evoked potential amplitude (P<0.05), with the increase maintained until 30 min after stimulation. The motor-evoked potential amplitude immediately after stimulation was not significantly different between the 20 and 30 Hz frequencies. The results indicated that repetitive magnetic stimulation increased motor-evoked potential amplitude of swallowing muscles, suggesting facilitation of the motor cortex related to swallowing in healthy individuals.

  19. Neuromuscular Plasticity: Disentangling Stable and Variable Motor Maps in the Human Sensorimotor Cortex

    PubMed Central

    Kraus, Dominic

    2016-01-01

    Motor maps acquired with transcranial magnetic stimulation (TMS) are evolving as a biomarker for monitoring disease progression or the effects of therapeutic interventions. High test-retest reliability of this technique for long observation periods is therefore required to differentiate daily or weekly fluctuations from stable plastic reorganization of corticospinal connectivity. In this study, a novel projection, interpolation, and coregistration technique, which considers the individual gyral anatomy, was applied in healthy subjects for biweekly acquired TMS motor maps over a period of twelve weeks. The intraclass correlation coefficient revealed long-term reliability of motor maps with relevant interhemispheric differences. The sensorimotor cortex and nonprimary motor areas of the dominant hemisphere showed more extended and more stable corticospinal connectivity. Long-term correlations of the MEP amplitudes at each stimulation site revealed mosaic-like clusters of consistent corticospinal excitability. The resting motor threshold, centre of gravity, and mean MEPs across all TMS sites, as highly reliable cortical map parameters, could be disentangled from more variable parameters such as MEP area and volume. Cortical TMS motor maps provide high test-retest reliability for long-term monitoring when analyzed with refined techniques. They may guide restorative interventions which target dormant corticospinal connectivity for neurorehabilitation. PMID:27610248

  20. Sleep-Dependent Reactivation of Ensembles in Motor Cortex Promotes Skill Consolidation

    PubMed Central

    Ramanathan, Dhakshin S.; Gulati, Tanuj; Ganguly, Karunesh

    2015-01-01

    Despite many prior studies demonstrating offline behavioral gains in motor skills after sleep, the underlying neural mechanisms remain poorly understood. To investigate the neurophysiological basis for offline gains, we performed single-unit recordings in motor cortex as rats learned a skilled upper-limb task. We found that sleep improved movement speed with preservation of accuracy. These offline improvements were linked to both replay of task-related ensembles during non-rapid eye movement (NREM) sleep and temporal shifts that more tightly bound motor cortical ensembles to movements; such offline gains and temporal shifts were not evident with sleep restriction. Interestingly, replay was linked to the coincidence of slow-wave events and bursts of spindle activity. Neurons that experienced the most consistent replay also underwent the most significant temporal shift and binding to the motor task. Significantly, replay and the associated performance gains after sleep only occurred when animals first learned the skill; continued practice during later stages of learning (i.e., after motor kinematics had stabilized) did not show evidence of replay. Our results highlight how replay of synchronous neural activity during sleep mediates large-scale neural plasticity and stabilizes kinematics during early motor learning. PMID:26382320

  1. Sleep-Dependent Reactivation of Ensembles in Motor Cortex Promotes Skill Consolidation.

    PubMed

    Ramanathan, Dhakshin S; Gulati, Tanuj; Ganguly, Karunesh

    2015-01-01

    Despite many prior studies demonstrating offline behavioral gains in motor skills after sleep, the underlying neural mechanisms remain poorly understood. To investigate the neurophysiological basis for offline gains, we performed single-unit recordings in motor cortex as rats learned a skilled upper-limb task. We found that sleep improved movement speed with preservation of accuracy. These offline improvements were linked to both replay of task-related ensembles during non-rapid eye movement (NREM) sleep and temporal shifts that more tightly bound motor cortical ensembles to movements; such offline gains and temporal shifts were not evident with sleep restriction. Interestingly, replay was linked to the coincidence of slow-wave events and bursts of spindle activity. Neurons that experienced the most consistent replay also underwent the most significant temporal shift and binding to the motor task. Significantly, replay and the associated performance gains after sleep only occurred when animals first learned the skill; continued practice during later stages of learning (i.e., after motor kinematics had stabilized) did not show evidence of replay. Our results highlight how replay of synchronous neural activity during sleep mediates large-scale neural plasticity and stabilizes kinematics during early motor learning.

  2. Severe and extensive neonatal hearing loss in cats results in auditory cortex plasticity that differentiates into two regions.

    PubMed

    Rajan, R; Irvine, D R F

    2010-06-01

    We examined the response characteristics of primary auditory cortex (A1) neurons in adult cats partially but extensively deafened by ototoxic drugs 2-8 days after birth. The damage evoked extensive A1 topographic map reorganization as also found by others, but a novel finding was that in the majority of cats with low-frequency edges to the cochlear lesion, the area of reorganization segregated into two areas expressing the same novel frequency inputs but differentiated by neuronal sensitivity and responsiveness. Immediately adjacent to normal A1 is an approximately 1.2-mm-wide area of reorganization in which sensitivity and responsiveness to sound are similar to that in normal A1 in the same animals and in unlesioned adult animals. Extending further into deprived A1 is a more extensive area of reorganization where neurons have poorer sensitivity and responsiveness to new inputs. These two areas did not differ in response-area bandwidth and response latency. We interpret these novel changes as the cortical consequences of severe receptor organ lesions extending to low-frequency cochlear regions. We speculate that the two areas of A1 reorganization may reflect differences in the transcortical spatial distribution of thalamo-cortical and horizontal intracortical connections. Qualitatively similar changes in response properties have been seen after retinal lesions producing large areas of visual cortical reorganization, suggesting they might be a general consequence of receptor lesions that deprive large regions of cortex of normal input. These effects may have perceptual implications for the use of cochlear implants in patients with residual low-frequency hearing.

  3. Feedback from area 21a influences orientation but not direction maps in the primary visual cortex of the cat.

    PubMed

    Tong, Lei; Zhu, Bin; Li, Zhong; Shou, Tiande; Yu, Hongbo

    2011-10-24

    In the monkey's visual cortex, there are two well-documented information processing streams: the dorsal motion and ventral form/color pathways. Similarly, two corresponding information streams were also found in the cat's visual cortices, and PMLS and area 21a are the gateways for distinct motion and form information processing. It has been shown that the feedback from PMLS solely modulates motion direction, but not orientation response, while the feedback from area 21a modulates form related features, such as spatial frequency dependency and neuronal oblique effect. Here, we postulate that feedback signals from higher cortical areas in the form or the motion information pathway may solely modulate the corresponding properties in neurons in the lower areas of the visual system. To examine the above hypothesis, the impact of feedback from higher area 21a on both orientation and direction maps was investigated in area 17 of the cat using intrinsic signal optical imaging. The results showed that the feedback from area 21a did not affect the amplitude and preference of direction, but did modulate orientation response in area 17, supporting the above hypothesis.

  4. Neuronal connections of eye-dominance columns in the cat cerebral cortex after monocular deprivation.

    PubMed

    Alekseenko, S V; Toporova, S N; Shkorbatova, P Yu

    2008-09-01

    Plastic changes in intrahemisphere neuronal connections of the eye-dominance columns of cortical fields 17 and 18 were studied in monocularly deprived cats. The methodology consisted of microintophoretic administration of horseradish peroxidase into cortical columns and three-dimensional reconstruction of the areas of retrograde labeled cells. The eye dominance of columns was established, as were their coordinates in the projection of the visual field. In field 17, the horizontal connections of columns receiving inputs from the non-deprived eye via the crossed-over visual tracts were longer than the connections of the "non-crossed" columns of this eye and were longer than in normal conditions; the connections of the columns of the deprived eye were significantly reduced. Changes in the spatial organization of horizontal connections in field 17 were seen for the columns of the non-deprived eye (areas of labeled cells were rounder and the density of labeled cells in these areas were non-uniform). The longest horizontal connections in deprived cats were no longer than the lengths of these connections in cats with strabismus. It is suggested that the axon length of cells giving rise to the horizontal connections of cortical columns has a limit which is independent of visual stimulation during the critical period of development of the visual system.

  5. Neural plasticity maintained high by activation of cyclic AMP-dependent protein kinase: an age-independent, general mechanism in cat striate cortex.

    PubMed

    Imamura, K; Kasamatsu, T; Tanaka, S

    2007-06-29

    Adult cats lack ocular dominance plasticity, showing little change in the ocular dominance distribution following monocular deprivation. Ocular dominance plasticity is also lost in kitten visual cortex that has been continuously infused with either catecholaminergic neurotoxin, beta-adrenoreceptor blocker, or inhibitor of cyclic AMP-dependent protein kinase (protein kinase A). Complementarily, in adult cats we showed earlier that pharmacological activation of protein kinase A, albeit partially, restored ocular dominance plasticity. In the present study, we first asked whether, mediated by protein kinase A activation, the same molecular mechanisms could restore ocular dominance plasticity to kitten cortex that once lost the expression of plasticity due to prior pharmacological treatments. Concurrently with monocular deprivation, two kinds of cyclic AMP-related drugs (cholera toxin A-subunit or dibutyryl cyclic AMP) were directly infused in two types of aplastic kitten cortex pretreated with either 6-hydroxydopamine or propranolol. The combined treatment resulted in clear ocular dominance shift to the non-deprived eye, indicating that cortical plasticity was fully restored to aplastic kitten cortex. Next, to directly prove the sensitivity difference in protein kinase A activation between the immature and mature cortex, we compared the thus-obtained data in kittens with the published data derived from adult cats under the comparable experimental paradigm. The extent of ocular dominance changes following monocular deprivation was compared at different drug concentrations in the two preparations: the shifted ocular dominance distribution in aplastic kitten cortex infused with dibutyryl cyclic AMP at the lowest concentration tested and the W-shaped distribution in similarly treated adult cortex at a thousandfold-higher drug concentration that induced nearly maximal changes. We conclude that, irrespective of the animal's age, activation of protein kinase A cascades is a

  6. Aspects of static and dynamic motor function in peripheral nerve regeneration: SSI and CatWalk gait analysis.

    PubMed

    Bozkurt, A; Scheffel, J; Brook, G A; Joosten, E A; Suschek, C V; O'Dey, D M; Pallua, N; Deumens, R

    2011-05-16

    Assessment of the therapeutic potential of interventions to bridge-repair peripheral nerve defects heavily relies on the demonstration of improved functional outcome. In the present study we used CatWalk gait analysis (locomotor-test) and Static Sciatic Index (SSI) (static-toe-spread-test) to assess the behavioural benefits of autologous nerve transplantation (ANT) repair of 2-cm rat sciatic nerve defects (neurotmesis-lesion). A reproducible and standardised rat sciatic nerve crush lesion model (axonotmesis-lesion) was used to assess the extent of recovery supported by maximal axon regeneration (measured by SSI and CatWalk). Animals were behaviourally followed for a period of 10 weeks. SSI analysis showed that ANT induced a significant improvement in motor deficit from about -95 to -65, however, CatWalk analysis did not show any major indication of locomotor recovery. This discrepancy might suggest that improvements in static motor functions (such as toe spreading) could reflect an early indicator for the recovery of function. We also noted differences in axon regeneration including increased axon density, smaller axon diameters and thinner myelin sheaths in the distal region of the ANT in comparison to the equivalent region of crushed and normal nerves. This difference in axon regeneration may be related to the clearly improved toe spreading function. We conclude that SSI and CatWalk present different advantages and disadvantages for the assessment of motor recovery after bridge-repair of peripheral nerve defects.

  7. Motor Cortex Excitability and BDNF Levels in Chronic Musculoskeletal Pain According to Structural Pathology

    PubMed Central

    Caumo, Wolnei; Deitos, Alícia; Carvalho, Sandra; Leite, Jorge; Carvalho, Fabiana; Dussán-Sarria, Jairo Alberto; Lopes Tarragó, Maria da Graça; Souza, Andressa; Torres, Iraci Lucena da Silva; Fregni, Felipe

    2016-01-01

    The central sensitization syndrome (CSS) encompasses disorders with overlapping symptoms in a structural pathology spectrum ranging from persistent nociception [e.g., osteoarthritis (OA)] to an absence of tissue injuries such as the one presented in fibromyalgia (FM) and myofascial pain syndrome (MPS). First, we hypothesized that these syndromes present differences in their cortical excitability parameters assessed by transcranial magnetic stimulation (TMS), namely motor evoked potential (MEP), cortical silent period (CSP), short intracortical inhibition (SICI) and short intracortical facilitation (SICF). Second, considering that the presence of tissue injury could be detected by serum neurotrophins, we hypothesized that the spectrum of structural pathology (i.e., from persistent nociception like in OA, to the absence of tissue injury like in FM and MPS), could be detected by differential efficiency of their descending pain inhibitory system, as assessed by the conditioned pain modulation (CPM) paradigm. Third, we explored whether brain-derived neurotrophic factor (BDNF) had an influence on the relationship between motor cortex excitability and structural pathology. This cross-sectional study pooled baseline data from three randomized clinical trials. We included females (n = 114), aged 19–65 years old with disability by chronic pain syndromes (CPS): FM (n = 19), MPS (n = 54), OA (n = 27) and healthy subjects (n = 14). We assessed the serum BDNF, the motor cortex excitability by parameters the TMS measures and the change on numerical pain scale [NPS (0–10)] during CPM-task. The adjusted mean (SD) on the SICI observed in the absence of tissue injury was 56.36% lower than with persistent nociceptive input [0.31(0.18) vs. 0.55 (0.32)], respectively. The BDNF was inversely correlated with the SICI and with the change on NPS (0–10)during CPM-task. These findings suggest greater disinhibition in the motor cortex and the descending pain inhibitory system in FM and

  8. Learning-Dependent Potentiation in the Vibrissal Motor Cortex Is Closely Related to the Acquisition of Conditioned Whisker Responses in Behaving Mice

    ERIC Educational Resources Information Center

    Delgado-Garcia, Jose Maria; Troncoso, Julieta; Munera, Alejandro

    2007-01-01

    The role of the primary motor cortex in the acquisition of new motor skills was evaluated during classical conditioning of vibrissal protraction responses in behaving mice, using a trace paradigm. Conditioned stimulus (CS) presentation elicited a characteristic field potential in the vibrissal motor cortex, which was dependent on the synchronized…

  9. The effects of acute alcohol exposure on the response properties of neurons in visual cortex area 17 of cats

    SciTech Connect

    Chen Bo; Xia Jing; Li Guangxing; Zhou Yifeng

    2010-03-15

    Physiological and behavioral studies have demonstrated that a number of visual functions such as visual acuity, contrast sensitivity, and motion perception can be impaired by acute alcohol exposure. The orientation- and direction-selective responses of cells in primary visual cortex are thought to participate in the perception of form and motion. To investigate how orientation selectivity and direction selectivity of neurons are influenced by acute alcohol exposure in vivo, we used the extracellular single-unit recording technique to examine the response properties of neurons in primary visual cortex (A17) of adult cats. We found that alcohol reduces spontaneous activity, visual evoked unit responses, the signal-to-noise ratio, and orientation selectivity of A17 cells. In addition, small but detectable changes in both the preferred orientation/direction and the bandwidth of the orientation tuning curve of strongly orientation-biased A17 cells were observed after acute alcohol administration. Our findings may provide physiological evidence for some alcohol-related deficits in visual function observed in behavioral studies.

  10. Modulation of human motor cortex excitability by single doses of amantadine.

    PubMed

    Reis, Janine; John, Daniel; Heimeroth, Antje; Mueller, Hans-Helge; Oertel, Wolfgang H; Arndt, Torsten; Rosenow, Felix

    2006-12-01

    Amantadine-sulfate has been used for several decades to treat acute influenza A, Parkinson's disease (PD), and acute or chronic drug-induced dyskinesia. Several mechanisms of actions detected in vivo/in vitro including N-methyl-D-aspartate (NMDA)-receptor antagonism, blockage of potassium channels, dopamine receptor agonism, enhancement of noradrenergic release, and anticholinergic effects have been described. We used transcranial magnetic stimulation (TMS) to evaluate the effect of single doses of amantadine on human motor cortex excitability in normal subjects. Using a double-blind, placebo-controlled, crossover study design, motor thresholds, recruitment curves, cortical stimulation-induced silent period (CSP), short intracortical inhibition (ICI), intracortical facilitation (ICF), and late inhibition (L-ICI) in 14 healthy subjects were investigated after oral doses of 50 and 100 mg amantadine with single and paired pulse TMS paradigms. Spinal cord excitability was investigated by distal latencies and M-amplitudes of the abductor digiti minimi muscle. After intake of amantadine, a significant dose-dependent decrease of ICF was noticed as well as a significant increase of L-ICI as compared to placebo. The effect on ICF and L-ICI significantly correlated with amantadine serum levels. ICI was slightly increased after amantadine intake, but the effect failed to be significant. Furthermore, amantadine had no significant effects on motor thresholds, MEP recruitment curves, CSP, or peripheral excitability. In conclusion, a low dose of amantadine is sufficient in modulating human motor cortex excitability. The decrease of ICF and increase of L-ICI may reflect glutamatergic modulation or a polysynaptic interaction of glutamatergic and GABA-ergic circuits. Although amantadine has several mechanisms of action, the NMDA-receptor antagonism seems to be the most relevant effect on cortical excitability. As L-ICI can be influenced by this type of drug, it may be an interesting

  11. Reorganization of Motor Cortex after Controlled Cortical Impact in Rats and Implications for Functional Recovery

    PubMed Central

    Nishibe, Mariko; Barbay, Scott; Guggenmos, David

    2010-01-01

    Abstract We report the results of controlled cortical impact (CCI) centered on the caudal forelimb area (CFA) of rat motor cortex to determine the feasibility of examining cortical plasticity in a spared cortical motor area (rostral forelimb area, RFA). We compared the effects of three CCI parameter sets (groups CCI-1, CCI-2, and CCI-3) that differed in impactor surface shape, size, and location, on behavioral recovery and RFA structural and functional integrity. Forelimb deficits in the limb contralateral to the injury were evident in all three CCI groups assessed by skilled reach and footfault tasks that persisted throughout the 35-day post-CCI assessment period. Nissl-stained coronal sections revealed that the RFA was structurally intact. Intracortical microstimulation experiments conducted at 7 weeks post-CCI demonstrated that RFA was functionally viable. However, the size of the forelimb representation decreased significantly in CCI-1 compared to the control group. Subdivided into component movement categories, there was a significant group effect for proximal forelimb movements. The RFA area reduction and reorganization are discussed in relation to possible diaschisis, and to compensatory functional behavior, respectively. Also, an inverse correlation between the anterior extent of the lesion and the size of the RFA was identified and is discussed in relation to corticocortical connectivity. The results suggest that CCI can be applied to rat CFA while sparing RFA. This CCI model can contribute to our understanding of neural plasticity in premotor cortex as a substrate for functional motor recovery. PMID:20873958

  12. Continuous Force Decoding from Local Field Potentials of the Primary Motor Cortex in Freely Moving Rats

    PubMed Central

    Khorasani, Abed; Heydari Beni, Nargess; Shalchyan, Vahid; Daliri, Mohammad Reza

    2016-01-01

    Local field potential (LFP) signals recorded by intracortical microelectrodes implanted in primary motor cortex can be used as a high informative input for decoding of motor functions. Recent studies show that different kinematic parameters such as position and velocity can be inferred from multiple LFP signals as precisely as spiking activities, however, continuous decoding of the force magnitude from the LFP signals in freely moving animals has remained an open problem. Here, we trained three rats to press a force sensor for getting a drop of water as a reward. A 16-channel micro-wire array was implanted in the primary motor cortex of each trained rat, and obtained LFP signals were used for decoding of the continuous values recorded by the force sensor. Average coefficient of correlation and the coefficient of determination between decoded and actual force signals were r = 0.66 and R2 = 0.42, respectively. We found that LFP signal on gamma frequency bands (30–120 Hz) had the most contribution in the trained decoding model. This study suggests the feasibility of using low number of LFP channels for the continuous force decoding in freely moving animals resembling BMI systems in real life applications. PMID:27767063

  13. Inference and Decoding of Motor Cortex Low-Dimensional Dynamics via Latent State-Space Models

    PubMed Central

    Aghagolzadeh, Mehdi; Truccolo, Wilson

    2016-01-01

    Motor cortex neuronal ensemble spiking activity exhibits strong low-dimensional collective dynamics (i.e., coordinated modes of activity) during behavior. Here, we demonstrate that these low-dimensional dynamics, revealed by unsupervised latent state-space models, can provide as accurate or better reconstruction of movement kinematics as direct decoding from the entire recorded ensemble. Ensembles of single neurons were recorded with triple microelectrode arrays (MEAs) implanted in ventral and dorsal premotor (PMv, PMd) and primary motor (M1) cortices while nonhuman primates performed 3-D reach-to-grasp actions. Low-dimensional dynamics were estimated via various types of latent state-space models including, for example, Poisson linear dynamic system (PLDS) models. Decoding from low-dimensional dynamics was implemented via point process and Kalman filters coupled in series. We also examined decoding based on a predictive subsampling of the recorded population. In this case, a supervised greedy procedure selected neuronal subsets that optimized decoding performance. When comparing decoding based on predictive subsampling and latent state-space models, the size of the neuronal subset was set to the same number of latent state dimensions. Overall, our findings suggest that information about naturalistic reach kinematics present in the recorded population is preserved in the inferred low-dimensional motor cortex dynamics. Furthermore, decoding based on unsupervised PLDS models may also outperform previous approaches based on direct decoding from the recorded population or on predictive subsampling. PMID:26336135

  14. Changes of Brain Connectivity in the Primary Motor Cortex After Subcortical Stroke

    PubMed Central

    Li, Yongxin; Wang, Defeng; Zhang, Heye; Wang, Ya; Wu, Ping; Zhang, Hongwu; Yang, Yang; Huang, Wenhua

    2016-01-01

    Abstract The authors investigated the changes in connectivity networks of the bilateral primary motor cortex (M1) of subcortical stroke patients using a multimodal neuroimaging approach with antiplatelet therapy. Nineteen patients were scanned at 2 time points: before and 1 month after the treatment. The authors assessed the resting-state functional connectivity (FC) and probabilistic fiber tracking of left and right M1 of every patient, and then compared these results to the 15 healthy controls. The authors also evaluated the correlations between the neuroimaging results and clinical scores. Compared with the controls, the patients showed a significant decrease of FC in the contralateral motor cortex before treatment, and the disrupted FC was restored after treatment. The fiber tracking results in the controls indicated that the body of the corpus callosum should be the main pathway connecting the M1 and contralateral hemispheres. All patients exhibited reduced probability of structural connectivity within this pathway before treatment and which was restored after treatment. Significant correlations were also found in these patients between the connectivity results and clinical scores, which might imply that the connectivity of M1 can be used to evaluate the motor skills in stroke patients. These findings can help elucidate the neural mechanisms responsible for the brain connectivity recovery after stroke. PMID:26871777

  15. Chronometric electrical stimulation of right inferior frontal cortex increases motor braking.

    PubMed

    Wessel, Jan R; Conner, Christopher R; Aron, Adam R; Tandon, Nitin

    2013-12-11

    The right inferior frontal cortex (rIFC) is important for stopping responses. Recent research shows that it is also activated when response emission is slowed down when stopping is anticipated. This suggests that rIFC also functions as a goal-driven brake. Here, we investigated the causal role of rIFC in goal-driven braking by using computer-controlled, event-related (chronometric), direct electrical stimulation (DES). We compared the effects of rIFC stimulation on trials in which responses were made in the presence versus absence of a stopping-goal ("Maybe Stop" [MS] vs "No Stop" [NS]). We show that DES of rIFC slowed down responses (compared with control-site stimulation) and that rIFC stimulation induced more slowing when motor braking was required (MS) compared with when it was not (NS). Our results strongly support a causal role of a rIFC-based network in inhibitory motor control. Importantly, the results extend this causal role beyond externally driven stopping to goal-driven inhibitory control, which is a richer model of human self-control. These results also provide the first demonstration of double-blind chronometric DES of human prefrontal cortex, and suggest that--in the case of rIFC--this could lead to augmentation of motor braking.

  16. Memory accumulation mechanisms in human cortex are independent of motor intentions.

    PubMed

    Sestieri, Carlo; Tosoni, Annalisa; Mignogna, Valeria; McAvoy, Mark P; Shulman, Gordon L; Corbetta, Maurizio; Romani, Gian Luca

    2014-05-14

    Previous studies on perceptual decision-making have often emphasized a tight link between decisions and motor intentions. Human decisions, however, also depend on memories or experiences that are not closely tied to specific motor responses. Recent neuroimaging findings have suggested that, during episodic retrieval, parietal activity reflects the accumulation of evidence for memory decisions. It is currently unknown, however, whether these evidence accumulation signals are functionally linked to signals for motor intentions coded in frontoparietal regions and whether activity in the putative memory accumulator tracks the amount of evidence for only previous experience, as reflected in "old" reports, or for both old and new decisions, as reflected in the accuracy of memory judgments. Here, human participants used saccadic-eye and hand-pointing movements to report recognition judgments on pictures defined by different degrees of evidence for old or new decisions. A set of cortical regions, including the middle intraparietal sulcus, showed a monotonic variation of the fMRI BOLD signal that scaled with perceived memory strength (older > newer), compatible with an asymmetrical memory accumulator. Another set, including the hippocampus and the angular gyrus, showed a nonmonotonic response profile tracking memory accuracy (higher > lower evidence), compatible with a symmetrical accumulator. In contrast, eye and hand effector-specific regions in frontoparietal cortex tracked motor intentions but were not modulated by the amount of evidence for the effector outcome. We conclude that item recognition decisions are supported by a combination of symmetrical and asymmetrical accumulation signals largely segregated from motor intentions.

  17. Disruption of primary motor cortex before learning impairs memory of movement dynamics.

    PubMed

    Richardson, Andrew G; Overduin, Simon A; Valero-Cabré, Antoni; Padoa-Schioppa, Camillo; Pascual-Leone, Alvaro; Bizzi, Emilio; Press, Daniel Z

    2006-11-29

    Although multiple lines of evidence implicate the primary motor cortex (M1) in motor learning, the precise role of M1 in the adaptation to novel movement dynamics and in the subsequent consolidation of a memory of those dynamics remains unclear. Here we used repetitive transcranial magnetic stimulation (rTMS) to dissociate the contribution of M1 to these distinct aspects of motor learning. Subjects performed reaching movements in velocity-dependent force fields over three epochs: a null-field baseline epoch, a clockwise-field learning epoch (15 min after the baseline epoch), and a clockwise-field retest epoch (24 h after the learning epoch). Half of the subjects received 15 min of 1 Hz rTMS to M1 between the baseline and learning epochs. Subjects given rTMS performed identically to control subjects during the learning epoch. However, control subjects performed with significantly less error than rTMS subjects in the retest epoch on the following day. These results suggest that M1 is not critical to the network supporting motor adaptation per se but that, within this network, M1 may be important for initiating the development of long-term motor memories.

  18. Central command does not decrease cardiac parasympathetic efferent nerve activity during spontaneous fictive motor activity in decerebrate cats.

    PubMed

    Kadowaki, Akito; Matsukawa, Kanji; Wakasugi, Rie; Nakamoto, Tomoko; Liang, Nan

    2011-04-01

    To examine whether withdrawal of cardiac vagal efferent nerve activity (CVNA) predominantly controls the tachycardia at the start of exercise, the responses of CVNA and cardiac sympathetic efferent nerve activity (CSNA) were directly assessed during fictive motor activity that occurred spontaneously in unanesthetized, decerebrate cats. CSNA abruptly increased by 71 ± 12% at the onset of the motor activity, preceding the tachycardia response. The increase in CSNA lasted for 4-5 s and returned to the baseline, even though the motor activity was not ended. The increase of 6 ± 1 beats/min in heart rate appeared with the same time course of the increase in CSNA. In contrast, CVNA never decreased but increased throughout the motor activity, in parallel with a rise in mean arterial blood pressure (MAP). The peak increase in CVNA was 37 ± 9% at 5 s after the motor onset. The rise in MAP gradually developed to 21 ± 2 mmHg and was sustained throughout the spontaneous motor activity. Partial sinoaortic denervation (SAD) blunted the baroreflex sensitivity of the MAP-CSNA and MAP-CVNA relationship to 22-33% of the control. Although partial SAD blunted the initial increase in CSNA to 53% of the control, the increase in CSNA was sustained throughout the motor activity. In contrast, partial SAD almost abolished the increase in CVNA during the motor activity, despite the augmented elevation of 31 ± 1 mmHg in MAP. Because afferent inputs from both muscle receptors and arterial baroreceptors were absent or greatly attenuated in the partial SAD condition, only central command was operating during spontaneous fictive motor activity in decerebrate cats. Therefore, it is likely that central command causes activation of cardiac sympathetic outflow but does not produce withdrawal of cardiac parasympathetic outflow during spontaneous motor activity.

  19. ‘Simplification’ of responses of complex cells in cat striate cortex: suppressive surrounds and ‘feedback’ inactivation

    PubMed Central

    Bardy, Cedric; Huang, Jin Yu; Wang, Chun; FitzGibbon, Thomas; Dreher, Bogdan

    2006-01-01

    In mammalian striate cortex (V1), two distinct functional classes of neurones, the so-called simple and complex cells, are routinely distinguished. They can be quantitatively differentiated from each other on the basis of the ratio between the phase-variant (F1) component and the mean firing rate (F0) of spike responses to luminance-modulated sinusoidal gratings (simple, F1/F0 > 1; complex, F1/F0 < 1). We investigated how recurrent cortico-cortical connections affect the spatial phase-variance of responses of V1 cells in the cat. F1/F0 ratios of the responses to optimally oriented drifting sine-wave gratings covering the classical receptive field (CRF) of single V1 cells were compared to those of: (1) responses to gratings covering the CRFs combined with gratings of different orientations presented to the ‘silent’ surrounds; and (2) responses to CRF stimulation during reversible inactivation of postero-temporal visual (PTV) cortex. For complex cells, the relative strength of the silent surround suppression on CRF-driven responses was positively correlated with the extent of increases in F1/F0 ratios. Inactivation of PTV cortex increased F1/F0 ratios of CRF-driven responses of complex cells only. Overall, activation of suppressive surrounds or inactivation of PTV ‘converted’ substantial proportions (50 and 30%, respectively) of complex cells into simple-like cells (F1/F0 > 1). Thus, the simple–complex distinction depends, at least partly, on information coming from the silent surrounds and/or feedback from ‘higher-order’ cortices. These results support the idea that simple and complex cells belong to the same basic cortical circuit and the spatial phase-variance of their responses depends on the relative strength of different synaptic inputs. PMID:16709635

  20. Effects of age at cordotomy and subsequent exercise on contraction times of motor units in the cat.

    PubMed

    Smith, L A; Eldred, E; Edgerton, V R

    1993-12-01

    The contraction times (CTs) of functionally isolated motor units (MUs) in the soleus (SOL) and medial gastrocnemius (MG) muscles were determined in cats that had been spinalized at ages 2 (n = 15) or 12 (n = 9) wk and then either subjected to exercise on a treadmill or simply given manipulative care of the hindlimbs. The MUs were tested approximately 12 wk after the low-thoracic cordotomy, and comparisons were made with data from control animals. The CT of 50.9 ms obtained for SOL units (n = 163) in the spinal cats was 22% shorter than the mean of 65.0 ms for MUs (n = 57) from control cats (n = 4). Contrary to expectation, the CT in animals spinalized at 12 wk was significantly shorter than that in the 2-wk group. The CT for MG units (n = 105) in spinal cats was also significantly shorter (11%) than that in controls cats (n = 66, 6 cats), and those units identified by their high fatigue index as being of slow or fatigue-resistant type had a shorter CT than units with a low index. No distinction in CT of exercised and nonexercised groups was detected for either muscle. These findings are discussed in relation to the bearing influences of supraspinal and segmental origin have on CT duration in SOL and MG muscles during growth of the kitten. A slight, significant decrease (6%) in the fatigue index of SOL MUs (n = 144) was detected, but the values remained high (mean 0.87).

  1. Structural and functional definition of the motor cortex in the monkey (Macaca fascicularis).

    PubMed

    Sessle, B J; Wiesendanger, M

    1982-02-01

    1. The details of the organization of the motor cortex and its anterior and posterior border were investigated in three monkeys by a combination of techniques including intracortical microstimulation (i.c.m.s.), electrophysiological recording of cutaneous and muscle afferent inputs to single cortical neurones, and electrophysiological and anatomical identification of corticospinal neurones; in addition, data from these methods were related to cortical cytoarchitecture.2. Almost 5000 individual cortical loci were tested with i.c.m.s. in the unanaesthetized monkeys. In this paper, we particularly consider the organization of the forelimb motor representation, and its relation to the representation of other parts of the body. I.c.m.s. thresholds of about 5 muA were common for evoking twitch movements and e.m.g. responses in distal forelimb and face, jaw and tongue muscles, but proximal forelimb, trunk and hind-limb movements also sometimes had such low thresholds.3. The fingers were found to be represented nearest the central sulcus, with horseshoe-shaped bands of cortical tissue representing progressively more proximal muscles situated around this central ;finger core'.4. Cytoarchitectonically, the cortex having these low-threshold motor effects was characteristic of area 4. There was also a close fit between the extent of this ;excitable cortex' and the extent of densely spaced corticospinal neurones identified electro-physiologically or with horseradish peroxidase labelling. In subsequent mapping of forelimb afferents to the cortex when the animal was deeply anaesthetized, low-threshold and short-latency responses to muscle nerve stimulation were rarely found in this ;excitable cortex'.5. The anterior border could be clearly established by i.c.m.s. and by the sharp boundary of corticospinal neurones. It was noted that the motor cortex extends rostrally beyond area 4 and its anterior border appears to reside in the posterior part of area 6aalpha (Vogt & Vogt, 1919

  2. Transcranial magnetic stimulation reveals two functionally distinct stages of motor cortex involvement during perception of emotional body language.

    PubMed

    Borgomaneri, Sara; Gazzola, Valeria; Avenanti, Alessio

    2015-09-01

    Studies indicate that perceiving emotional body language recruits fronto-parietal regions involved in action execution. However, the nature of such motor activation is unclear. Using transcranial magnetic stimulation (TMS) we provide correlational and causative evidence of two distinct stages of motor cortex engagement during emotion perception. Participants observed pictures of body expressions and categorized them as happy, fearful or neutral while receiving TMS over the left or right motor cortex at 150 and 300 ms after picture onset. In the early phase (150 ms), we observed a reduction of excitability for happy and fearful emotional bodies that was specific to the right hemisphere and correlated with participants' disposition to feel personal distress. This 'orienting' inhibitory response to emotional bodies was also paralleled by a general drop in categorization accuracy when stimulating the right but not the left motor cortex. Conversely, at 300 ms, greater excitability for negative, positive and neutral movements was found in both hemispheres. This later motor facilitation marginally correlated with participants' tendency to assume the psychological perspectives of others and reflected simulation of the movement implied in the neutral and emotional body expressions. These findings highlight the motor system's involvement during perception of emotional bodies. They suggest that fast orienting reactions to emotional cues--reflecting neural processing necessary for visual perception--occur before motor features of the observed emotional expression are simulated in the motor system and that distinct empathic dispositions influence these two neural motor phenomena. Implications for theories of embodied simulation are discussed.

  3. Responses evoked in the cerebellar cortex by stimulation of the caudate nucleus in the cat

    PubMed Central

    Fox, Mary; Williams, T. D.

    1968-01-01

    1. Responses evoked in the cerebellar cortex following stimulation of caudate nucleus are described. 2. The evoked responses recorded from the surface of the cerebellar cortex were found to be of two types, one with a short (4-6 msec) latency and one with a longer (12-17 msec) latency. 3. The short latency response was maximal in the lobulus simplex, the longer latency response was maximal in paramedian lobule. 4. Following lesions in the inferior olive the longer latency response was absent. 5. Recordings from within the cerebellar cortex showed that the short latency response was uniformly distributed throughout the grey matter, the longer latency response was maximal in the region of the Purkinje cell bodies. 6. It was concluded that the short latency response was due to activation via the mossy fibres and the longer latency response to activation via the climbing fibres. 7. It was found that responses could be evoked in the cerebellum following stimulation of only the latero-ventral part of the caudate nucleus; stimulation of the rest of the nucleus caused no response in the cerebellum. This division of the caudate nucleus into two parts is similar to the subdivision of the caudate nucleus made by other workers using different criteria. PMID:5698279

  4. The contribution of transcranial magnetic stimulation in the functional evaluation of microcircuits in human motor cortex.

    PubMed

    Di Lazzaro, Vincenzo; Ziemann, Ulf

    2013-01-01

    Although transcranial magnetic stimulation (TMS) activates a number of different neuron types in the cortex, the final output elicited in corticospinal neurones is surprisingly stereotyped. A single TMS pulse evokes a series of descending corticospinal volleys that are separated from each other by about 1.5 ms (i.e., ~670 Hz). This evoked descending corticospinal activity can be directly recorded by an epidural electrode placed over the high cervical cord. The earliest wave is thought to originate from the direct activation of the axons of fast-conducting pyramidal tract neurones (PTN) and is therefore termed "D" wave. The later waves are thought to originate from indirect, trans-synaptic activation of PTNs and are termed "I" waves. The anatomical and computational characteristics of a canonical microcircuit model of cerebral cortex composed of layer II and III and layer V excitatory pyramidal cells, inhibitory interneurons, and cortico-cortical and thalamo-cortical inputs can account for the main characteristics of the corticospinal activity evoked by TMS including its regular and rhythmic nature, the stimulus intensity-dependence and its pharmacological modulation. In this review we summarize present knowledge of the physiological basis of the effects of TMS of the human motor cortex describing possible interactions between TMS and simple canonical microcircuits of neocortex. According to the canonical model, a TMS pulse induces strong depolarization of the excitatory cells in the superficial layers of the circuit. This leads to highly synchronized recruitment of clusters of excitatory neurons, including layer V PTNs, and of inhibitory interneurons producing a high frequency (~670 Hz) repetitive discharge of the corticospinal axons. The role of the inhibitory circuits is crucial to entrain the firing of the excitatory networks to produce a high-frequency discharge and to control the number and magnitude of evoked excitatory discharge in layer V PTNs. In summary

  5. Dose-response curve of associative plasticity in human motor cortex and interactions with motor practice.

    PubMed

    Elahi, Behzad; Hutchison, William D; Daskalakis, Z Jeff; Gunraj, Carolyn; Chen, Robert

    2014-02-01

    Associative plasticity is hypothesized to be an important neurophysiological correlate of memory formation and learning with potentials for applications in neurorehabilitation and for the development of new electrophysiological measures to study disorders of cortical plasticity. We hypothesized that the magnitude of the paired associative stimulation (PAS)-induced long-term potentiation (LTP)-like effect depends on the number of pairs in the PAS protocol. We also hypothesized that homeostatic interaction of PAS with subsequent motor learning is related to the magnitude of the PAS-induced LTP-like effect. We studied 10 healthy subjects. In experiment 1a, subjects received 90 (PAS90), 180 (PAS180), or 270 (PAS270) pairs of stimuli, followed by a dynamic motor practice (DMP) 1 h after the end of the PAS protocols. In experiment 1b, the DMP preceded the PAS protocol. In experiment 2, the time course of PAS270 was studied. We found that PAS270 resulted in greater increase in motor evoked potential (MEP) amplitude compared with protocols with fewer pairs of stimuli. Moreover, the interaction between PAS protocols with motor learning differed depending on the number of stimulus pairs used to induce PAS. While DMP alone increased MEP amplitudes, DMP during the LTP-like effects induced by PAS270 led to a long-term depression (LTD)-like effect (homeostatic interaction). This homeostatic interaction did not occur after PAS90 and PAS180. In conclusion, we found a dose-dependent effect of the number of stimulus pairs used in the PAS protocol on cortical plasticity. Homeostatic interaction between PAS and DMP was observed only after PAS270.

  6. Corticospinal activity evoked and modulated by non-invasive stimulation of the intact human motor cortex.

    PubMed

    Di Lazzaro, Vincenzo; Rothwell, John C

    2014-10-01

    A number of methods have been developed recently that stimulate the human brain non-invasively through the intact scalp. The most common are transcranial magnetic stimulation (TMS), transcranial electric stimulation (TES) and transcranial direct current stimulation (TDCS). They are widely used to probe function and connectivity of brain areas as well as therapeutically in a variety of conditions such as depression or stroke. They are much less focal than conventional invasive methods which use small electrodes placed on or in the brain and are often thought to activate all classes of neurones in the stimulated area. However, this is not true. A large body of evidence from experiments on the motor cortex shows that non-invasive methods of brain stimulation can be surprisingly selective and that adjusting the intensity and direction of stimulation can activate different classes of inhibitory and excitatory inputs to the corticospinal output cells. Here we review data that have elucidated the action of TMS and TES, concentrating mainly on the most direct evidence available from spinal epidural recordings of the descending corticospinal volleys. The results show that it is potentially possible to test and condition specific neural circuits in motor cortex that could be affected differentially by disease, or be used in different forms of natural behaviour. However, there is substantial interindividual variability in the specificity of these protocols. Perhaps in the future it will be possible, with the advances currently being made to model the electrical fields induced in individual brains, to develop forms of stimulation that can reliably target more specific populations of neurones, and open up the internal circuitry of the motor cortex for study in behaving humans.

  7. Principal components of hand kinematics and neurophysiological signals in motor cortex during reach to grasp movements

    PubMed Central

    Aggarwal, Vikram; Thakor, Nitish V.; Schieber, Marc H.

    2014-01-01

    A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects. PMID:24990564

  8. Potential Mechanisms Supporting the Value of Motor Cortex Stimulation to Treat Chronic Pain Syndromes

    PubMed Central

    DosSantos, Marcos F.; Ferreira, Natália; Toback, Rebecca L.; Carvalho, Antônio C.; DaSilva, Alexandre F.

    2016-01-01

    Throughout the first years of the twenty-first century, neurotechnologies such as motor cortex stimulation (MCS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS) have attracted scientific attention and been considered as potential tools to centrally modulate chronic pain, especially for those conditions more difficult to manage and refractory to all types of available pharmacological therapies. Interestingly, although the role of the motor cortex in pain has not been fully clarified, it is one of the cortical areas most commonly targeted by invasive and non-invasive neuromodulation technologies. Recent studies have provided significant advances concerning the establishment of the clinical effectiveness of primary MCS to treat different chronic pain syndromes. Concurrently, the neuromechanisms related to each method of primary motor cortex (M1) modulation have been unveiled. In this respect, the most consistent scientific evidence originates from MCS studies, which indicate the activation of top-down controls driven by M1 stimulation. This concept has also been applied to explain M1-TMS mechanisms. Nevertheless, activation of remote areas in the brain, including cortical and subcortical structures, has been reported with both invasive and non-invasive methods and the participation of major neurotransmitters (e.g., glutamate, GABA, and serotonin) as well as the release of endogenous opioids has been demonstrated. In this critical review, the putative mechanisms underlying the use of MCS to provide relief from chronic migraine and other types of chronic pain are discussed. Emphasis is placed on the most recent scientific evidence obtained from chronic pain research studies involving MCS and non-invasive neuromodulation methods (e.g., tDCS and TMS), which are analyzed comparatively. PMID:26903788

  9. Principal components of hand kinematics and neurophysiological signals in motor cortex during reach to grasp movements.

    PubMed

    Mollazadeh, Mohsen; Aggarwal, Vikram; Thakor, Nitish V; Schieber, Marc H

    2014-10-15

    A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects.

  10. Effects of cerebellar transcranial alternating current stimulation on motor cortex excitability and motor function.

    PubMed

    Naro, Antonino; Bramanti, Alessia; Leo, Antonino; Manuli, Alfredo; Sciarrone, Francesca; Russo, Margherita; Bramanti, Placido; Calabrò, Rocco Salvatore

    2017-01-07

    The cerebellum regulates several motor functions through two main mechanisms, the cerebellum-brain inhibition (CBI) and the motor surround inhibition (MSI). Although the exact cerebellar structures and functions involved in such processes are partially known, Purkinje cells (PC) and their surrounding interneuronal networks may play a pivotal role concerning CBI and MSI. Cerebellar transcranial alternating current stimulation (tACS) has been proven to shape specific cerebellar components in a feasible, safe, effective, and non-invasive manner. The aim of our study was to characterize the cerebellar structures and functions subtending CBI and MSI using a tACS approach. Fifteen healthy individuals underwent a cerebellar tACS protocol at 10, 50, and 300 Hz, or a sham-tACS over the right cerebellar hemisphere. We measured the tACS aftereffects on motor-evoked potential (MEP) amplitude, CBI induced by tACS (tiCBI) at different frequencies, MSI, and hand motor task performance. None of the participants had any side effect related to tACS. After 50-Hz tACS, we observed a clear tiCBI-50Hz weakening (about +30%, p < 0.001) paralleled by a MEP amplitude increase (about +30%, p = 0.001) and a reduction of the time required to complete some motor task (about -20%, p = 0.01), lasting up to 30 min. The 300-Hz tACS induced a selective, specific tiCBI-300Hz and tiCBI-50Hz modulation in surrounding muscles (about -15%, p = 0.01) and MSI potentiation (about +40%, p < 0.001). The 10-Hz tACS and the sham-tACS were ineffective (p > 0.6). Our preliminary data suggest that PC may represent the last mediator of tiCBI and that the surrounding interneuronal network may have an important role in updating MSI, tiCBI, and M1 excitability during tonic muscle contraction, by acting onto the PC. The knowledge of these neurophysiological issues offers new cues to design innovative, non-invasive neuromodulation protocols to shape cerebellar-cerebral functions.

  11. Stochastic resonance in the spinal cord and somatosensory cortex of the cat

    NASA Astrophysics Data System (ADS)

    Manjarrez, Elias; Rojas-Piloni, Gerardo; Perez, Hugo; Mendez, Ignacio; Hernandez-Paxtian, Zulma; Flores, Amira

    2003-05-01

    The aim of this study was to demonstrate the occurrence of stochastic resonance (SR) in spinal and cortical potentials elicited by periodic tactile stimuli in the anaesthetised cat. The periodic tactile stimuli were applied on the central pad of the hindpaw and the noisy tactile stimuli on the glabrous skin of the third hindpaw digit. This protocol allowed that the signal and noise were mixed not in the skin but in the somatosensory regions of the central nervous system. The results show that a particular level of tactile noise can increase the amplitude of the spinal and cortical potentials elicited by periodic tactile stimuli. The topographical distribution of evoked potentials indicates that the effects of noise were spatially restricted. All cats showed distinct SR behavior at the spinal and cortical stages of the sensory encoding. Such SR was abolished in the cortical but not in the spinal recording after the sectioning of the ascending pathways. This suggests that the spinal neurones may also contribute to the SR observed at the cortical level. The present study documents the first evidence that the SR phenomenon occurs in the spinal and cortical somatosensory system itself and not only in the peripheral sensory receptors.

  12. Morphological Bases of Suppressive and Facilitative Spatial Summation in the Striate Cortex of the Cat

    PubMed Central

    Li, Chao-Yi

    2010-01-01

    In V1 of cats and monkeys, activity of neurons evoked by stimuli within the receptive field can be modulated by stimuli in the extra-receptive field (ERF). This modulating effect can be suppressive (S-ERF) or facilitatory (F-ERF) and plays different roles in visual information processing. Little is known about the cellular bases underlying the different types of ERF modulating effects. Here, we focus on the morphological differences between the S-ERF and F-ERF neurons. Single unit activities were recorded from V1 of the cat. The ERF properties of each neuron were assessed by area-response functions using sinusoidal grating stimuli. On completion of the functional tests, the cells were injected intracellularly with biocytin. The labeled cells were reconstructed and morphologically characterized in terms of the ERF modulation effects. We show that the vast majority of S-ERF neurons and F-ERF neurons are pyramidal cells and that the two types of cells clearly differ in the size of the soma, in complexity of dendrite branching, in spine size and density, and in the range of innervations of the axon collaterals. We propose that different pyramidal cell phenotypes reflect a high degree of specificity of neuronal connections associated with different types of spatial modulation. PMID:21151335

  13. Contribution of LFP dynamics to single-neuron spiking variability in motor cortex during movement execution

    PubMed Central

    Rule, Michael E.; Vargas-Irwin, Carlos; Donoghue, John P.; Truccolo, Wilson

    2015-01-01

    Understanding the sources of variability in single-neuron spiking responses is an important open problem for the theory of neural coding. This variability is thought to result primarily from spontaneous collective dynamics in neuronal networks. Here, we investigate how well collective dynamics reflected in motor cortex local field potentials (LFPs) can account for spiking variability during motor behavior. Neural activity was recorded via microelectrode arrays implanted in ventral and dorsal premotor and primary motor cortices of non-human primates performing naturalistic 3-D reaching and grasping actions. Point process models were used to quantify how well LFP features accounted for spiking variability not explained by the measured 3-D reach and grasp kinematics. LFP features included the instantaneous magnitude, phase and analytic-signal components of narrow band-pass filtered (δ,θ,α,β) LFPs, and analytic signal and amplitude envelope features in higher-frequency bands. Multiband LFP features predicted single-neuron spiking (1ms resolution) with substantial accuracy as assessed via ROC analysis. Notably, however, models including both LFP and kinematics features displayed marginal improvement over kinematics-only models. Furthermore, the small predictive information added by LFP features to kinematic models was redundant to information available in fast-timescale (<100 ms) spiking history. Overall, information in multiband LFP features, although predictive of single-neuron spiking during movement execution, was redundant to information available in movement parameters and spiking history. Our findings suggest that, during movement execution, collective dynamics reflected in motor cortex LFPs primarily relate to sensorimotor processes directly controlling movement output, adding little explanatory power to variability not accounted by movement parameters. PMID:26157365

  14. Effects of subthalamic nucleus stimulation on motor cortex plasticity in Parkinson disease

    PubMed Central

    Kim, Sang Jin; Udupa, Kaviraja; Ni, Zhen; Moro, Elena; Gunraj, Carolyn; Mazzella, Filomena; Lozano, Andres M.; Hodaie, Mojgan; Lang, Anthony E.

    2015-01-01

    Objective: We hypothesized that subthalamic nucleus (STN) deep brain stimulation (DBS) will improve long-term potentiation (LTP)-like plasticity in motor cortex in Parkinson disease (PD). Methods: We studied 8 patients with PD treated with STN-DBS and 9 age-matched healthy controls. Patients with PD were studied in 4 sessions in medication (Med) OFF/stimulator (Stim) OFF, Med-OFF/Stim-ON, Med-ON/Stim-OFF, and Med-ON/Stim-ON states in random order. Motor evoked potential amplitude and cortical silent period duration were measured at baseline before paired associated stimulation (PAS) and at 3 different time intervals (T0, T30, T60) up to 60 minutes after PAS in the abductor pollicis brevis and abductor digiti minimi muscles. Results: Motor evoked potential size significantly increased after PAS in controls (+67.7% of baseline at T30) and in patients in the Med-ON/Stim-ON condition (+55.8% of baseline at T30), but not in patients in the Med-OFF/Stim-OFF (−0.4% of baseline at T30), Med-OFF/Stim-ON (+10.3% of baseline at T30), and Med-ON/Stim-OFF conditions (+17.3% of baseline at T30). Cortical silent period duration increased after PAS in controls but not in patients in all test conditions. Conclusions: Our findings suggest that STN-DBS together with dopaminergic medications restore LTP-like plasticity in motor cortex in PD. Restoration of cortical plasticity may be one of the mechanisms of how STN-DBS produces clinical benefit. PMID:26156511

  15. Exercise combined with low-level GABAA receptor inhibition up-regulates the expression of neurotrophins in the motor cortex.

    PubMed

    Takahashi, Kazuma; Maejima, Hiroshi; Ikuta, Gaku; Mani, Hiroki; Asaka, Tadayoshi

    2017-01-01

    Neurotrophins play a crucial role in neuroplasticity, neurogenesis, and neuroprotection in the central nervous system. Aerobic exercise is known to increase the expression of BDNF in the cerebral cortex. Several animal studies have evaluated the tonic inhibition of GABAergic synapses to enhance hippocampal plasticity as well as learning and memory, whereas the effects of GABAergic inhibition on plasticity in the cerebral cortex related to motor learning are not well characterized. The objective of the present study was to examine the interactive effect of low-level GABAA receptor inhibition and exercise on the expression of neurotrophins including BDNF in the murine motor cortex. ICR mice were randomly distributed among 4 groups based on two factors of GABAA receptor inhibition and exercise, i.e. control group, an exercise group, a bicuculline group, and an exercise plus bicuculline group. We administered GABAA receptor antagonist, bicuculline intraperitoneally to the mice (bicuculline and exercise plus bicuculline group) at a non-epileptic dose of 0.25mg/kg, whereas the mice (exercise and exercise plus bicuculline group) were exercised on a treadmill for 1h every day. After two week intervention, the expression of mRNA and protein abundance of neurotrophins in the motor cortex was assayed using Real time PCR and ELISA. BDNF gene expression was significantly increased by approximately 3-fold in the bicuculline group relative to the control, exercise, and bicuculline plus exercise groups. Protein abundance of BDNF expression was significantly increased by approximately 3-fold in the bicuculline plus exercise group relative to other groups. Therefore, the present study revealed that combined GABAA receptor inhibition and moderate aerobic exercise up-regulated BDNF protein expression in the motor cortex without producing side effects on motor or cognitive functions. Alterations in BDNF expression could positively contribute to plasticity by regulating the balance

  16. Interactions of acoustic and somatosensory evoked responses in a polysensory cortex of the cat.

    PubMed

    Toldi, J; Fehér, O

    1987-01-01

    Interactions of acoustic and somatosensory evoked potentials were studied in the anterior suprasylvian gyrus of the cat. The interactions showed dynamic changes and were susceptible to different kinds of influences. The interactions could be influenced by synchronous activation of the acoustic and somatosensory inputs with 2 Hz frequency, or by elevating the stimulus frequency. Interactions could be influenced by amphetamine and gamma-glutamyl-taurine, drugs known as capable of influencing the arousal level of the brain. The antagonists of amphetamine prevented this effect. Drugs acting on the cortical GABA-ergic system proved also to be decisive in the interactions of evoked potentials of different origins. In some experiments unit activity was recorded parallel with evoked potentials.

  17. The truth-telling motor cortex: response competition in M1 discloses deceptive behaviour.

    PubMed

    Hadar, Aviad A; Makris, Stergios; Yarrow, Kielan

    2012-02-01

    Neural circuits associated with response conflict are active during deception. Here we use transcranial magnetic stimulation to examine for the first time whether competing responses in primary motor cortex can be used to detect lies. Participants used their little finger or thumb to respond either truthfully or deceitfully regarding facial familiarity. Motor-evoked-potentials (MEPs) from muscles associated with both digits tracked the development of each motor plan. When preparing to deceive, the MEP of the non-responding digit (i.e. the plan corresponding to the truth) exceeds the MEP of the responding digit (i.e. the lie), whereas a mirror-reversed pattern occurs when telling the truth. This give away response conflict interacts with the time of stimulation during a speeded reaction period. Lies can even activate digit-specific cortical representations when only verbal responses are made. Our findings support neurobiological models which blend cognitive decision-making with motor programming, and suggest a novel index for discriminating between honest and intentionally false facial recognition.

  18. An unavoidable modulation? Sensory attention and human primary motor cortex excitability.

    PubMed

    Ruge, Diane; Muggleton, Neil; Hoad, Damon; Caronni, Antonio; Rothwell, John C

    2014-09-01

    The link between basic physiology and its modulation by cognitive states, such as attention, is poorly understood. A significant association becomes apparent when patients with movement disorders describe experiences with changing their attention focus and the fundamental effect that this has on their motor symptoms. Moreover, frequently used mental strategies for treating such patients, e.g. with task-specific dystonia, widely lack laboratory-based knowledge about physiological mechanisms. In this largely unexplored field, we looked at how the locus of attention, when it changed between internal (locus hand) and external (visual target), influenced excitability in the primary motor cortex (M1) in healthy humans. Intriguingly, both internal and external attention had the capacity to change M1 excitability. Both led to a reduced stimulation-induced GABA-related inhibition and a change in motor evoked potential size, i.e. an overall increased M1 excitability. These previously unreported findings indicated: (i) that cognitive state differentially interacted with M1 physiology, (ii) that our view of distraction (attention locus shifted towards external or distant location), which is used as a prevention or management strategy for use-dependent motor disorders, is too simple and currently unsupported for clinical application, and (iii) the physiological state reached through attention modulation represents an alternative explanation for frequently reported electrophysiology findings in neuropsychiatric disorders, such as an aberrant inhibition.

  19. Associations between force and fatigue in fast-twitch motor units of a cat hindlimb muscle.

    PubMed

    Laouris, Y; Bevan, L; Reinking, R M; Stuart, D G

    2004-01-01

    Associations were quantified between the control force and fatigue-induced force decline in 22 single fast-twitch-fatigable motor units of 5 deeply anesthetized adult cats. The units were subjected to intermittent stimulation at 1 train/s for 360 s. Two stimulation patterns were delivered in a pseudo-random manner. The first was a 500-ms train with constant interpulse intervals. The second pattern had the same number of stimuli, mean stimulus rate, and stimulus duration, but the stimulus pulses were rearranged to increase the force produced by the units in the control (prefatigue) state. The associations among the control peak tetanic force of these units, 3 indices of fatigue, and total cumulative force during fatiguing contractions were dependent, in part, on the stimulation pattern used to produce fatigue. The associations were also dependent, albeit to a lesser extent, on the force measure (peak vs. integrated) and the fatigue index used to quantify fatigue. It is proposed that during high-force fatiguing contractions, neural mechanisms are potentially available to delay and reduce the fatigue of fast-twitch-fatigable units for brief, but functionally relevant, periods. In contrast, the fatigue of slow-twitch fatigue-resistant units seems more likely to be controlled largely, if not exclusively, by metabolic processes within their muscle cells.

  20. Re-emergence of hand-muscle representations in human motor cortex after hand allograft

    PubMed Central

    Vargas, Claudia D.; Aballéa, Antoine; Rodrigues, Érika C.; Reilly, Karen T.; Mercier, Catherine; Petruzzo, Palmina; Dubernard, Jean M.; Sirigu, Angela

    2009-01-01

    The human primary motor cortex (M1) undergoes considerable reorganization in response to traumatic upper limb amputation. The representations of the preserved arm muscles expand, invading portions of M1 previously dedicated to the hand, suggesting that former hand neurons are reassigned to the control of remaining proximal upper limb muscles. Hand allograft offers a unique opportunity to study the reversibility of such long-term cortical changes. We used transcranial magnetic stimulation in patient LB, who underwent bilateral hand transplantation 3 years after a traumatic amputation, to longitudinally track both the emergence of intrinsic (from the donor) hand muscles in M1 as well as changes in the representation of stump (upper arm and forearm) muscles. The same muscles were also mapped in patient CD, the first bilateral hand allograft recipient. Newly transplanted intrinsic muscles acquired a cortical representation in LB's M1 at 10 months postgraft for the left hand and at 26 months for the right hand. The appearance of a cortical representation of transplanted hand muscles in M1 coincided with the shrinkage of stump muscle representations for the left but not for the right side. In patient CD, transcranial magnetic stimulation performed at 51 months postgraft revealed a complete set of intrinsic hand-muscle representations for the left but not the right hand. Our findings show that newly transplanted muscles can be recognized and integrated into the patient's motor cortex. PMID:19366678

  1. Development and Maturation of Embryonic Cortical Neurons Grafted into the Damaged Adult Motor Cortex

    PubMed Central

    Ballout, Nissrine; Frappé, Isabelle; Péron, Sophie; Jaber, Mohamed; Zibara, Kazem; Gaillard, Afsaneh

    2016-01-01

    Injury to the human central nervous system can lead to devastating consequences due to its poor ability to self-repair. Neural transplantation aimed at replacing lost neurons and restore functional circuitry has proven to be a promising therapeutical avenue. We previously reported in adult rodent animal models with cortical lesions that grafted fetal cortical neurons could effectively re-establish specific patterns of projections and synapses. The current study was designed to provide a detailed characterization of the spatio-temporal in vivo development of fetal cortical transplanted cells within the lesioned adult motor cortex and their corresponding axonal projections. We show here that as early as 2 weeks after grafting, cortical neuroblasts transplanted into damaged adult motor cortex developed appropriate projections to cortical and subcortical targets. Grafted cells initially exhibited characteristics of immature neurons, which then differentiated into mature neurons with appropriate cortical phenotypes where most were glutamatergic and few were GABAergic. All cortical subtypes identified with the specific markers CTIP2, Cux1, FOXP2, and Tbr1 were generated after grafting as evidenced with BrdU co-labeling. The set of data provided here is of interest as it sets biological standards for future studies aimed at replacing fetal cells with embryonic stem cells as a source of cortical neurons. PMID:27536221

  2. Automatic detection and quantitative analysis of cells in the mouse primary motor cortex

    NASA Astrophysics Data System (ADS)

    Meng, Yunlong; He, Yong; Wu, Jingpeng; Chen, Shangbin; Li, Anan; Gong, Hui

    2014-09-01

    Neuronal cells play very important role on metabolism regulation and mechanism control, so cell number is a fundamental determinant of brain function. Combined suitable cell-labeling approaches with recently proposed three-dimensional optical imaging techniques, whole mouse brain coronal sections can be acquired with 1-μm voxel resolution. We have developed a completely automatic pipeline to perform cell centroids detection, and provided three-dimensional quantitative information of cells in the primary motor cortex of C57BL/6 mouse. It involves four principal steps: i) preprocessing; ii) image binarization; iii) cell centroids extraction and contour segmentation; iv) laminar density estimation. Investigations on the presented method reveal promising detection accuracy in terms of recall and precision, with average recall rate 92.1% and average precision rate 86.2%. We also analyze laminar density distribution of cells from pial surface to corpus callosum from the output vectorizations of detected cell centroids in mouse primary motor cortex, and find significant cellular density distribution variations in different layers. This automatic cell centroids detection approach will be beneficial for fast cell-counting and accurate density estimation, as time-consuming and error-prone manual identification is avoided.

  3. Early hypersynchrony in juvenile PINK1(-)/(-) motor cortex is rescued by antidromic stimulation.

    PubMed

    Carron, Romain; Filipchuk, Anton; Nardou, Romain; Singh, Abhinav; Michel, Francois J; Humphries, Mark D; Hammond, Constance

    2014-01-01

    In Parkinson's disease (PD), cortical networks show enhanced synchronized activity but whether this precedes motor signs is unknown. We investigated this question in PINK1(-)/(-) mice, a genetic rodent model of the PARK6 variant of familial PD which shows impaired spontaneous locomotion at 16 months. We used two-photon calcium imaging and whole-cell patch clamp in slices from juvenile (P14-P21) wild-type or PINK1(-)/(-) mice. We designed a horizontal tilted cortico-subthalamic slice where the only connection between cortex and subthalamic nucleus (STN) is the hyperdirect cortico-subthalamic pathway. We report excessive correlation and synchronization in PINK1(-)/(-) M1 cortical networks 15 months before motor impairment. The percentage of correlated pairs of neurons and their strength of correlation were higher in the PINK1(-)/(-) M1 than in the wild type network and the synchronized network events involved a higher percentage of neurons. Both features were independent of thalamo-cortical pathways, insensitive to chronic levodopa treatment of pups, but totally reversed by antidromic invasion of M1 pyramidal neurons by axonal spikes evoked by high frequency stimulation (HFS) of the STN. Our study describes an early excess of synchronization in the PINK1(-)/(-) cortex and suggests a potential role of antidromic activation of cortical interneurons in network desynchronization. Such backward effect on interneurons activity may be of importance for HFS-induced network desynchronization.

  4. Disruption of Locomotor Adaptation with Repetitive Transcranial Magnetic Stimulation Over the Motor Cortex.

    PubMed

    Choi, Julia T; Bouyer, Laurent J; Nielsen, Jens Bo

    2015-07-01

    Locomotor patterns are adapted on a trial-and-error basis to account for predictable dynamics. Once a walking pattern is adapted, the new calibration is stored and must be actively de-adapted. Here, we tested the hypothesis that storage of newly acquired ankle adaptation in walking is dependent on corticospinal mechanisms. Subjects were exposed to an elastic force that resisted ankle dorsiflexion during treadmill walking. Ankle movement was adapted in <30 strides, leading to after-effects on removal of the force. We used a crossover design to study the effects of repetitive transcranial magnetic stimulation (TMS) over the primary motor cortex (M1), compared with normal adaptation without TMS. In addition, we tested the effects of TMS over the primary sensory cortex (S1) and premotor cortex (PMC) during adaptation. We found that M1 TMS, but not S1 TMS and PMC TMS, reduced the size of ankle dorsiflexion after-effects. The results suggest that suprathreshold M1 TMS disrupted the initial processes underlying locomotor adaptation. These results are consistent with the hypothesis that corticospinal mechanisms underlie storage of ankle adaptation in walking.

  5. Hypoactivation in right inferior frontal cortex is specifically associated with motor response inhibition in adult ADHD

    PubMed Central

    Morein-Zamir, Sharon; Dodds, Chris; van Hartevelt, Tim J; Schwarzkopf, Wolfgang; Sahakian, Barbara; Müller, Ulrich; Robbins, Trevor

    2014-01-01

    Adult ADHD has been linked to impaired motor response inhibition and reduced associated activation in the right inferior frontal cortex (IFC). However, it is unclear whether abnormal inferior frontal activation in adult ADHD is specifically related to a response inhibition deficit or reflects a more general deficit in attentional processing. Using functional magnetic resonance imaging, we tested a group of 19 ADHD patients with no comorbidities and a group of 19 healthy control volunteers on a modified go/no-go task that has been shown previously to distinguish between cortical responses related to response inhibition and attentional shifting. Relative to the healthy controls, ADHD patients showed increased commission errors and reduced activation in inferior frontal cortex during response inhibition. Crucially, this reduced activation was observed when controlling for attentional processing, suggesting that hypoactivation in right IFC in ADHD is specifically related to impaired response inhibition. The results are consistent with the notion of a selective neurocognitive deficit in response inhibition in adult ADHD associated with abnormal functional activation in the prefrontal cortex, whilst ruling out likely group differences in attentional orienting, arousal and motivation. Hum Brain Mapp 35:5141–5152, 2014. PMID:24819224

  6. Subthalamic nucleus stimulation modulates motor cortex oscillatory activity in Parkinson's disease.

    PubMed

    Devos, D; Labyt, E; Derambure, P; Bourriez, J L; Cassim, F; Reyns, N; Blond, S; Guieu, J D; Destée, A; Defebvre, L

    2004-02-01

    In Parkinson's disease, impaired motor preparation has been related to an increased latency in the appearance of movement-related desynchronization (MRD) throughout the contralateral primary sensorimotor (PSM) cortex. Internal globus pallidus (GPi) stimulation improved movement desynchronization over the PSM cortex during movement execution but failed to improve impaired motor preparation. PET studies indicate that subthalamic nucleus (STN) stimulation partly reverses the abnormal premotor pattern of brain activation during movement. By monitoring MRD, we aimed to assess changes in premotor and PSM cortex oscillatory activity induced by bilateral STN stimulation and to compare these changes with those induced by l-dopa. Ten Parkinson's disease patients and a group of healthy, age-matched controls performed self-paced wrist flexions in each of four conditions: without either stimulation or l-dopa (the 'off' condition), with stimulation and without l-dopa (On Stim), with l-dopa and without stimulation ('on drug'), and with both stimulation and l-dopa (On Both). Compared with the Off condition, in both the On Stim and the On Drug condition the Unified Parkinson's Disease Rating Scale (UPDRS) III score decreased by about 60% and in the On Both condition it decreased by 80%. The desynchronization latency over central regions contralateral to movement and the movement desynchronization over bilateral central regions were significantly increased by stimulation and by l-dopa, with a maximal effect when the two were associated. Furthermore, desynchronization latency significantly decreased over bilateral frontocentral regions in the three treatment conditions compared with the Off condition. In Parkinson's disease, STN stimulation may induce a change in abnormal cortical oscillatory activity patterns (similar to that produced by l-dopa) by decreasing the abnormal spreading of desynchronization over frontocentral regions and increasing PSM cortex activity during movement

  7. Facilitating skilled right hand motor function in older subjects by anodal polarization over the left primary motor cortex.

    PubMed

    Hummel, Friedhelm C; Heise, Kirstin; Celnik, Pablo; Floel, Agnes; Gerloff, Christian; Cohen, Leonardo G

    2010-12-01

    Healthy ageing is accompanied by limitations in performance of activities of daily living and personal independence. Recent reports demonstrated improvements in motor function induced by noninvasive anodal direct current stimulation (tDCS) of the primary motor cortex (M1) in young healthy adults. Here we tested the hypothesis that a single session of anodal tDCS over left M1 could facilitate performance of right upper extremity tasks required for activities of daily living (Jebsen-Taylor hand function test, JTT) in older subjects relative to Sham in a double-blind cross-over study design. We found (a) significant improvement in JTT function with tDCS relative to Sham that outlasted the stimulation period by at least 30 min, (b) that the older the subjects the more prominent this improvement appeared and (c) that consistent with previous results in younger subjects, these effects were not accompanied by any overt undesired side effect. We conclude that anodal tDCS applied over M1 can facilitate performance of skilled hand functions required for activities of daily living in older subjects.

  8. Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex

    PubMed Central

    Fuhl, Anna; Müller-Dahlhaus, Florian; Lücke, Caroline; Toennes, Stefan W; Ziemann, Ulf

    2015-01-01

    Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOH<10mM, EtOH<20mM) was compared to single oral doses of alprazolam (APZ, 1mg) a classical benzodiazepine, and zolpidem (ZLP, 10 mg), a non-benzodiazepine hypnotic, in a double-blinded randomized placebo-controlled crossover design in ten healthy human subjects. EtOH<10mM and EtOH<20mM but not APZ or ZLP enhanced the PASLTD-induced LTD-like plasticity, while APZ and ZLP but not EtOH<10mM or EtOH<20mM decreased SPV. Non-sedating low doses of ethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks. PMID:26038159

  9. Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex.

    PubMed

    Fuhl, Anna; Müller-Dahlhaus, Florian; Lücke, Caroline; Toennes, Stefan W; Ziemann, Ulf

    2015-12-01

    Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOH<10mM, EtOH<20mM) was compared to single oral doses of alprazolam (APZ, 1mg) a classical benzodiazepine, and zolpidem (ZLP, 10 mg), a non-benzodiazepine hypnotic, in a double-blinded randomized placebo-controlled crossover design in ten healthy human subjects. EtOH<10mM and EtOH<20mM but not APZ or ZLP enhanced the PASLTD-induced LTD-like plasticity, while APZ and ZLP but not EtOH<10mM or EtOH<20mM decreased SPV. Non-sedating low doses of ethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks.

  10. Negative blood oxygenation level dependent homunculus and somatotopic information in primary motor cortex and supplementary motor area.

    PubMed

    Zeharia, Noa; Hertz, Uri; Flash, Tamar; Amedi, Amir

    2012-11-06

    A crucial attribute in movement encoding is an adequate balance between suppression of unwanted muscles and activation of required ones. We studied movement encoding across the primary motor cortex (M1) and supplementary motor area (SMA) by inspecting the positive and negative blood oxygenation level-dependent (BOLD) signals in these regions. Using periodic and event-related experiments incorporating the bilateral/axial movements of 20 body parts, we report detailed mototopic imaging maps in M1 and SMA. These maps were obtained using phase-locked analysis. In addition to the positive BOLD, significant negative BOLD was detected in M1 but not in the SMA. The negative BOLD spatial pattern was neither located at the ipsilateral somatotopic location nor randomly distributed. Rather, it was organized somatotopically across the entire homunculus and inversely to the positive BOLD, creating a negative BOLD homunculus. The neuronal source of negative BOLD is unclear. M1 provides a unique system to test whether the origin of negative BOLD is neuronal, because different arteries supply blood to different regions in the homunculus, ruling out blood-stealing explanations. Finally, multivoxel pattern analysis showed that positive BOLD in M1 and SMA and negative BOLD in M1 contain somatotopic information, enabling prediction of the moving body part from inside and outside its somatotopic location. We suggest that the neuronal processes underlying negative BOLD participate in somatotopic encoding in M1 but not in the SMA. This dissociation may emerge because of differences in the activity of these motor areas associated with movement suppression.

  11. Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area

    PubMed Central

    Fiori, Francesca; Chiappini, Emilio; Soriano, Marco; Paracampo, Riccardo; Romei, Vincenzo; Borgomaneri, Sara; Avenanti, Alessio

    2016-01-01

    The primary motor cortex (M1) is strongly influenced by several frontal regions. Dual-site transcranial magnetic stimulation (dsTMS) has highlighted the timing of early (<40 ms) prefrontal/premotor influences over M1. Here we used dsTMS to investigate, for the first time, longer-latency causal interactions of the posterior inferior frontal gyrus (pIFG) and pre-supplementary motor area (pre-SMA) with M1 at rest. A suprathreshold test stimulus (TS) was applied over M1 producing a motor-evoked potential (MEP) in the relaxed hand. Either a subthreshold or a suprathreshold conditioning stimulus (CS) was administered over ipsilateral pIFG/pre-SMA sites before the TS at different CS-TS inter-stimulus intervals (ISIs: 40–150 ms). Independently of intensity, CS over pIFG and pre-SMA (but not over a control site) inhibited MEPs at an ISI of 40 ms. The CS over pIFG produced a second peak of inhibition at an ISI of 150 ms. Additionally, facilitatory modulations were found at an ISI of 60 ms, with supra- but not subthreshold CS intensities. These findings suggest differential modulatory roles of pIFG and pre-SMA in M1 excitability. In particular, the pIFG –but not the pre-SMA– exerts intensity-dependent modulatory influences over M1 within the explored time window of 40-150 ms, evidencing fine-tuned control of M1 output. PMID:27929075

  12. Comparison of effects of transcranial magnetic stimulation on primary motor cortex and supplementary motor area in motor skill learning (randomized, cross over study).

    PubMed

    Kim, Yong Kyun; Shin, Sung Hun

    2014-01-01

    Motor skills require quick visuomotor reaction time, fast movement time, and accurate performance. Primary motor cortex (M1) and supplementary motor area (SMA) are closely related in learning motor skills. Also, it is well known that high frequency repeated transcranial magnetic stimulation (rTMS) on these sites has a facilitating effect. The aim of this study was to compare the effects of high frequency rTMS activation of these two brain sites on learning of motor skills. Twenty three normal volunteers participated. Subjects were randomly stimulated on either brain area, SMA or M1. The motor task required the learning of sequential finger movements, explicitly or implicitly. It consisted of pressing the keyboard sequentially with their right hand on seeing 7 digits on the monitor explicitly, and then tapping the 7 digits by memorization, implicitly. Subjects were instructed to hit the keyboard as fast and accurately as possible. Using Musical Instrument Digital Interface (MIDI), the keyboard pressing task was measured before and after high frequency rTMS for motor performance, which was measured by response time (RT), movement time, and accuracy (AC). A week later, the same task was repeated by cross-over study design. At this time, rTMS was applied on the other brain area. Two-way ANOVA was used to assess the carry over time effect and stimulation sites (M1 and SMA), as factors. Results indicated that no carry-over effect was observed. The AC and RT were not different between the two stimulating sites (M1 and SMA). But movement time was significantly decreased after rTMS on both SMA and M1. The amount of shortened movement time after rTMS on SMA was significantly increased as compared to the movement time after rTMS on M1 (p < 0.05), especially for implicit learning of motor tasks. The coefficient of variation was lower in implicit trial than in explicit trial. In conclusion, this finding indicated an important role of SMA compared to M1, in implicit motor

  13. Dynamics of single unit activity in the association cortex of waking cats during defensive conditioning.

    PubMed

    Shevko, G N; Bakanova, N F

    1981-01-01

    Responses of neurons in association area 5 during defensive conditioning to acoustic stimulation were studied in chronic experiments on cats. As a rule the neurons responded by excitation to presentation of conditioned and unconditioned stimuli. During the conditioned reflex unit responses usually appeared in the first 50 msec after the beginning of acoustic stimulation, i.e., they were connected with the action of the conditioned stimulus and not with manifestations of conditioned-reflex motion. The most significant changes in responses of cortical association units were observed in the initial period of conditioning. During stabilization of the conditioned reflex, responses of some neurons became stabilized, whereas in other neurons the spontaneous activity and intensity of responses increased, and in a third group the response to one of the stimuli disappeared. This last result indicated a switch during conditioning from polysensory unit responses to monosensory specialized responses. Extinctive inhibition was found to consist of a gradual decrease in the level of the spike discharge and its approximation to spontaneous activity, i.e., to be passive in character.

  14. Stimulus uncertainty enhances long-term potentiation-like plasticity in human motor cortex.

    PubMed

    Sale, Martin V; Nydam, Abbey S; Mattingley, Jason B

    2017-03-01

    Plasticity can be induced in human cortex using paired associative stimulation (PAS), which repeatedly and predictably pairs a peripheral electrical stimulus with transcranial magnetic stimulation (TMS) to the contralateral motor region. Many studies have reported small or inconsistent effects of PAS. Given that uncertain stimuli can promote learning, the predictable nature of the stimulation in conventional PAS paradigms might serve to attenuate plasticity induction. Here, we introduced stimulus uncertainty into the PAS paradigm to investigate if it can boost plasticity induction. Across two experimental sessions, participants (n = 28) received a modified PAS paradigm consisting of a random combination of 90 paired stimuli and 90 unpaired (TMS-only) stimuli. Prior to each of these stimuli, participants also received an auditory cue which either reliably predicted whether the upcoming stimulus was paired or unpaired (no uncertainty condition) or did not predict the upcoming stimulus (maximum uncertainty condition). Motor evoked potentials (MEPs) evoked from abductor pollicis brevis (APB) muscle quantified cortical excitability before and after PAS. MEP amplitude increased significantly 15 min following PAS in the maximum uncertainty condition. There was no reliable change in MEP amplitude in the no uncertainty condition, nor between post-PAS MEP amplitudes across the two conditions. These results suggest that stimulus uncertainty may provide a novel means to enhance plasticity induction with the PAS paradigm in human motor cortex. To provide further support to the notion that stimulus uncertainty and prediction error promote plasticity, future studies should further explore the time course of these changes, and investigate what aspects of stimulus uncertainty are critical in boosting plasticity.

  15. Motor cortex plasticity in Parkinson's disease and levodopa-induced dyskinesias.

    PubMed

    Morgante, Francesca; Espay, Alberto J; Gunraj, Carolyn; Lang, Anthony E; Chen, Robert

    2006-04-01

    Experimental models of Parkinson's disease have demonstrated abnormal synaptic plasticity in the corticostriatal system, possibly related to the development of levodopa-induced dyskinesias (LID). We tested the hypothesis that LID in Parkinson's disease is associated with aberrant plasticity in the human motor cortex (M1). We employed the paired associative stimulation (PAS) protocol, an experimental intervention involving transcranial magnetic stimulation (TMS) and median nerve stimulation capable of producing long-term potentiation (LTP) like changes in the sensorimotor system in humans. We studied the more affected side of 16 moderately affected patients with Parkinson's disease (9 dyskinetic, 7 non-dyskinetic) and the dominant side of 9 age-matched healthy controls. Motor-evoked potential (MEP) amplitudes and cortical silent period (CSP) duration were measured at baseline before PAS and for up to 60 min (T0, T30 and T60) after PAS in abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles. PAS significantly increased MEP size in controls (+74.8% of baseline at T30) but not in patients off medication (T30: +0.07% of baseline in the non-dyskinetic, +27% in the dyskinetic group). Levodopa restored the potentiation of MEP amplitudes by PAS in the non-dyskinetic group (T30: +64.9% of baseline MEP) but not in the dyskinetic group (T30: -9.2% of baseline). PAS prolonged CSP duration in controls. There was a trend towards prolongation of CSP in the non-dyskinetic group off medications but not in the dyskinetic group. Levodopa did not restore CSP prolongation by PAS in the dyskinetic group. Our findings suggest that LTP-like plasticity is deficient in Parkinson's disease off medications and is restored by levodopa in non-dyskinetic but not in dyskinetic patients. Abnormal synaptic plasticity in the motor cortex may play a role in the development of LID.

  16. Effects of antiepileptic drugs on associative LTP-like plasticity in human motor cortex.

    PubMed

    Heidegger, Tonio; Krakow, Karsten; Ziemann, Ulf

    2010-10-01

    Antiepileptic drugs (AEDs) are used extensively in clinical practice but relatively little is known on their specific effects at the systems level of human cortex. Here we tested, using a double-blind randomized placebo-controlled crossover design in healthy subjects, the effects of a single therapeutic oral dose of seven AEDs with different modes of action (tiagabine, diazepam, gabapentin, lamotrigine, topiramate, levetiracetam and piracetam) on long-term potentiation (LTP)-like motor cortical plasticity induced by paired associative transcranial magnetic stimulation (PAS). PAS-induced LTP-like plasticity was assessed from the increase in motor evoked potential amplitude in a hand muscle contralateral to the stimulated motor cortex. Levetiracetam significantly reduced LTP-like plasticity when compared to the placebo condition. Tiagabine, diazepam, lamotrigine and piracetam resulted in nonsignificant trends towards reduction of LTP-like plasticity while gabapentin and topiramate had no effect. The particularly depressant effect of levetiracetam is probably explained by its unique mode of action through binding at the vesicle membrane protein SV2A. Enhancement of gamma-amino butyric acid-dependent cortical inhibition by tiagabine, diazepam and possibly levetiracetam, and blockage of voltage-gated sodium channels by lamotrigine, may also depress PAS-induced LTP-like plasticity but these mechanisms appear to be less relevant. Findings may inform about AED-related adverse effects on important LTP-dependent central nervous systems processes such as learning or memory formation. The particular depressant effect of levetiracetam on LTP-like plasticity may also relate to the unique properties of this drug to inhibit epileptogenesis, a potentially LTP-associated process.

  17. Nonlinear dose-dependent impact of D1 receptor activation on motor cortex plasticity in humans.

    PubMed

    Fresnoza, Shane; Paulus, Walter; Nitsche, Michael A; Kuo, Min-Fang

    2014-02-12

    The neuromodulator dopamine plays an important role in synaptic plasticity. The effects are determined by receptor subtype specificity, concentration level, and the kind of neuroplasticity induced. D1-like receptors have been proposed to be involved in cognitive processes via their impact on plasticity. Cognitive studies in humans and animals revealed a dosage-dependent effect of D1-like receptor activation on task performance. In humans, D1-like receptor activation re-establishes plasticity under D2 receptor block. However, a dosage-dependent effect has not been explored so far. To determine the impact of the amount of D1-like receptor activation on neuroplasticity in humans, we combined sulpiride, a selective D2 receptor antagonist, with the dopamine precursor l-DOPA (25, 100, and 200 mg) or applied placebo medication. The impact on plasticity induced by anodal and cathodal transcranial direct current stimulation (tDCS) was compared with the impact on plasticity induced by excitatory and inhibitory paired associative stimulation (PAS) at the primary motor cortex of healthy humans. Stimulation-generated cortical excitability alterations were monitored by transcranial magnetic stimulation-induced motor-evoked potential amplitudes. D1-like receptor activation produced an inverted U-shaped dose-response curve on plasticity induced by both facilitatory tDCS and PAS. For excitability-diminishing tDCS and PAS, aftereffects were abolished or converted trendwise into facilitation. These data extend findings of dose-dependent inverted U-shaped effects of D1 receptor activation on neuroplasticity of the motor cortex.

  18. Stimulation over primary motor cortex during action observation impairs effector recognition.

    PubMed

    Naish, Katherine R; Barnes, Brittany; Obhi, Sukhvinder S

    2016-04-01

    Recent work suggests that motor cortical processing during action observation plays a role in later recognition of the object involved in the action. Here, we investigated whether recognition of the effector making an action is also impaired when transcranial magnetic stimulation (TMS) - thought to interfere with normal cortical activity - is applied over the primary motor cortex (M1) during action observation. In two experiments, single-pulse TMS was delivered over the hand area of M1 while participants watched short clips of hand actions. Participants were then asked whether an image (experiment 1) or a video (experiment 2) of a hand presented later in the trial was the same or different to the hand in the preceding video. In Experiment 1, we found that participants' ability to recognise static images of hands was significantly impaired when TMS was delivered over M1 during action observation, compared to when no TMS was delivered, or when stimulation was applied over the vertex. Conversely, stimulation over M1 did not affect recognition of dot configurations, or recognition of hands that were previously presented as static images (rather than action movie clips) with no object. In Experiment 2, we found that effector recognition was impaired when stimulation was applied part way through (300ms) and at the end (500ms) of the action observation period, indicating that 200ms of action-viewing following stimulation was not long enough to form a new representation that could be used for later recognition. The findings of both experiments suggest that interfering with cortical motor activity during action observation impairs subsequent recognition of the effector involved in the action, which complements previous findings of motor system involvement in object memory. This work provides some of the first evidence that motor processing during action observation is involved in forming representations of the effector that are useful beyond the action observation period.

  19. Motor learning and modulation of prefrontal cortex: an fNIRS assessment

    NASA Astrophysics Data System (ADS)

    Ono, Yumie; Noah, Jack Adam; Zhang, Xian; Nomoto, Yasunori; Suzuki, Tatsuya; Shimada, Sotaro; Tachibana, Atsumichi; Bronner, Shaw; Hirsch, Joy

    2015-12-01

    Objective. Prefrontal hemodynamic responses are observed during performance of motor tasks. Using a dance video game (DVG), a complex motor task that requires temporally accurate footsteps with given visual and auditory cues, we investigated whether 20 h of DVG training modified hemodynamic responses of the prefrontal cortex in six healthy young adults. Approach. Fronto-temporal activity during actual DVG play was measured using functional near-infrared spectroscopy (fNIRS) pre- and post-training. To evaluate the training-induced changes in the time-courses of fNIRS signals, we employed a regression analysis using the task-specific template fNIRS signals that were generated from alternate well-trained and/or novice DVG players. The HRF was also separately incorporated as a template to construct an alternate regression model. Change in coefficients for template functions at pre- and post- training were determined and compared among different models. Main results. Training significantly increased the motor performance using the number of temporally accurate steps in the DVG as criteria. The mean oxygenated hemoglobin (ΔoxyHb) waveform changed from an activation above baseline pattern to that of a below baseline pattern. Participants showed significantly decreased coefficients for regressors of the ΔoxyHb response of novice players and HRF. The model using ΔoxyHb responses from both well-trained and novice players of DVG as templates showed the best fit for the ΔoxyHb responses of the participants at both pre- and post-training when analyzed with Akaike information criteria. Significance. These results suggest that the coefficients for the template ΔoxyHb responses of the novice players are sensitive indicators of motor learning during the initial stage of training and thus clinically useful to determine the improvement in motor performance when patients are engaged in a specific rehabilitation program.

  20. The effects of rTMS over the primary motor cortex: the link between action and language.

    PubMed

    Repetto, Claudia; Colombo, Barbara; Cipresso, Pietro; Riva, Giuseppe

    2013-01-01

    Is the primary motor cortex (M1) necessary for language comprehension? The present study investigates the role of the primary motor cortex during verbs comprehension, within the framework of the embodied theories of language. We applied rTMS over the right and left hand portion of M1 and tested the effects of the stimulation toward the processing of hand-related action verbs versus abstract verbs. Results underlined a specific inhibition effect following left stimulation, only with hand-related action verbs. These findings seem to corroborate the hypothesis of a functional role of M1 in action verbs comprehension.

  1. Cross-reinnervated motor units in cat muscle. II. Soleus muscle reinnervated by flexor digitorum longus motoneurons.

    PubMed

    Dum, R P; O'Donovan, M J; Toop, J; Tsairis, P; Pinter, M J; Burke, R E

    1985-10-01

    The properties of whole soleus (SOL) muscles and of individual motor units were studied in cats 30-50 wk after self-reinnervation by soleus (SOL) motoneurons (SOL----SOL) or cross-reinnervation by flexor digitorum longus (FDL) motoneurons (FDL----SOL). As in the preceding paper (22), intracellular and glycogen-depletion methods were used to examine the physiological and histochemical properties of individual motor units. The results were compared with data from normal SOL motor units (8, 12). Intentionally self-reinnervated SOL muscles (SOL----SOL; n = 6) were normal in size and wet weight, and all of the five SOL----SOL motor units studied had physiological and histochemical characteristics that matched those of normal SOL units. Cross-reinnervation of SOL by FDL alpha-motoneurons (FDL----SOL; n = 7) produced muscles with wet weights and appearance essentially identical to normal SOL. However, whole-muscle twitch contraction times were much shorter (mean 60.4 ms) than those of normal (mean 136.9 ms, n = 18) or SOL----SOL muscles (mean 115.3 ms; n = 6). Despite this difference, none of the FDL----SOL muscles contained more than 7% histochemical type II muscle fibers, all of which were type IIA. Normal cat SOL muscles can contain up to 5% type IIA fibers, but none of our SOL----SOL muscles showed any type II fibers. Two FDL----SOL muscles had significant amounts of unintended self-reinnervation, permitting side-by-side comparison of FDL----SOL and SOL----SOL muscle fibers. The twitch contraction times of the two populations differed markedly, but they were histochemically indistinguishable except for the fact that SOL----SOL fibers had high neutral fat content (as do normal SOL fibers), whereas FDL----SOL showed much lower fat content. The 23 FDL----SOL muscle units studied were classified as physiological type S by criteria ("sag" test and fatigue resistance) used to identify motor-unit types in normal cat muscles. All five of the FDL----SOL units studied

  2. Neuronal loss due to prolonged controlled-current stimulation with chronically implanted microelectrodes in the cat cerebral cortex

    NASA Astrophysics Data System (ADS)

    McCreery, Douglas; Pikov, Victor; Troyk, Philip R.

    2010-06-01

    Activated iridium microelectrodes were implanted for 450-1282 days in the sensorimotor cortex of seven adult domestic cats and then pulsed for 240 h (8 h per day for 30 days) at 50 Hz. Continuous stimulation at 2 nC/phase and with a geometric charge density of 100 µC cm-2 produced no detectable change in neuronal density in the tissue surrounding the microelectrode tips. However, pulsing with a continuous 100% duty cycle at 4 nC/phase and with a geometric charge density of 200 µC cm-2 induced loss of cortical neurons over a radius of at least 150 µm from the electrode tips. The same stimulus regimen but with a duty cycle of 50% (1 s of stimulation, and then 1 s without stimulation repeated for 8 h) produced neuronal loss within a smaller radius, approximately 60 µm from the center of the electrode tips. However, there also was significant loss of neurons surrounding the unpulsed electrodes, presumably as a result of mechanical injury due to their insertion into and long-term residence in the tissue, and this was responsible for most of the neuronal loss within 150 µm of the electrodes pulsed with the 50% duty cycle.

  3. Cellular Mechanisms Underlying Behavioral State-Dependent Bidirectional Modulation of Motor Cortex Output

    PubMed Central

    Schiemann, Julia; Puggioni, Paolo; Dacre, Joshua; Pelko, Miha; Domanski, Aleksander; van Rossum, Mark C.W.; Duguid, Ian

    2015-01-01

    Summary Neuronal activity in primary motor cortex (M1) correlates with behavioral state, but the cellular mechanisms underpinning behavioral state-dependent modulation of M1 output remain largely unresolved. Here, we performed in vivo patch-clamp recordings from layer 5B (L5B) pyramidal neurons in awake mice during quiet wakefulness and self-paced, voluntary movement. We show that L5B output neurons display bidirectional (i.e., enhanced or suppressed) firing rate changes during movement, mediated via two opposing subthreshold mechanisms: (1) a global decrease in membrane potential variability that reduced L5B firing rates (L5Bsuppressed neurons), and (2) a coincident noradrenaline-mediated increase in excitatory drive to a subpopulation of L5B neurons (L5Benhanced neurons) that elevated firing rates. Blocking noradrenergic receptors in forelimb M1 abolished the bidirectional modulation of M1 output during movement and selectively impaired contralateral forelimb motor coordination. Together, our results provide a mechanism for how noradrenergic neuromodulation and network-driven input changes bidirectionally modulate M1 output during motor behavior. PMID:25981037

  4. Neural Summation in Human Motor Cortex by Subthreshold Transcranial Magnetic Stimulations

    PubMed Central

    Du, Xiaoming; Choa, Fow-Sen; Summerfelt, Ann; Tagamets, Malle A.; Rowland, Laura M.; Kochunov, Peter; Shepard, Paul; Hong, L. Elliot

    2014-01-01

    Integration of diverse synaptic inputs is a basic neuronal operation that relies on many neurocomputational principles, one of which is neural summation. However, we lack empirical understanding of neuronal summation in the human brains in vivo. Here we explored the effect of neural summation in the motor cortex using two subthreshold pulses of transcranial magnetic stimulation (TMS), each with intensities ranging from 60% - 95% of the resting motor threshold (RMT) and interstimulus intervals (ISI) varying from 1 – 25 ms. We found that two subthreshold TMS pulses can produce supra threshold motor response when ISIs were less than 10 ms, most prominent at 1, 1.5 and 3 ms. This facilitatory, above threshold response was evident when the intensity of the subthreshold pulses were above 80% of RMT but was absent as the intensity was 70% or below. Modeling of the summation data across intensity suggested that they followed an exponential function with excellent model fitting. Understanding the constraints for inducing summation of subthreshold stimulations to generate above threshold response may have implications in modeling neural operations and potential clinical applications. PMID:25399245

  5. Experimental simulation of cat electromyogram: evidence for algebraic summation of motor-unit action-potential trains.

    PubMed

    Day, S J; Hulliger, M

    2001-11-01

    Prompted by the observation that the slope of the relationship between average rectified electromyography (EMG) and the ensemble activation rate of a pool of motor units progressively decreased (showing a downward nonlinearity), an experimental study was carried out to test the widely held notion that the EMG is the simple algebraic sum of motor-unit action-potential trains. The experiments were performed on the cat soleus muscle under isometric conditions, using electrical stimulation of alpha-motor axons isolated in ventral root filaments. The EMG signals were simulated experimentally under conditions where the activation of nearly the entire pool of motor units or of subsets of motor units was completely controlled by the experimenter. Sets of individual motor units or of small groups of motor units were stimulated independently, using stimulation profiles that were strictly repeatable between trials. This permitted a rigorous quantitative comparison of EMGs that were recorded during combined activation of multiple motor filaments with EMGs that were synthesized from the algebraic summation of motor unit action potential trains generated by individual nerve filaments. These were recorded separately by individually stimulating the same filaments with the same activation profiles that were employed during combined stimulation. During combined activation of up to 10 motor filaments, experimentally recorded and computationally synthesized EMGs were virtually identical. This indicates that EMG signals indeed are the outcome of the simple algebraic summation of motor-unit action-potential trains generated by concurrently active motor units. For both recorded and synthesized EMGs, it was confirmed that EMG magnitude increased nonlinearly with the ensemble activation rate of a pool of motor units. The nonlinearity was largely abolished when EMG magnitude was estimated as the sum of rectified, instead of raw, motor-unit action-potential trains. This suggests that the

  6. Actions of compounds manipulating the nitric oxide system in the cat primary visual cortex.

    PubMed

    Cudeiro, J; Rivadulla, C; Rodríguez, R; Grieve, K L; Martínez-Conde, S; Acuña, C

    1997-10-15

    1. We iontophoretically applied NG-nitro-L-arginine (L-NOArg), an inhibitor of nitric oxide synthase (NOS), to cells (n = 77) in area 17 of anaesthetized and paralysed cats while recording single-unit activity extracellularly. In twenty-nine out of seventy-seven cells (38%), compounds altering NO levels affected visual responses. 2. In twenty-five out of twenty-nine cells, L-NOArg non-selectively reduced visually elicited responses and spontaneous activity. These effects were reversed by co-application of L-arginine (L-Arg), which was without effect when applied alone. Application of the NO donor diethylamine-nitric oxide (DEA-NO) produced excitation in three out of eleven cells, all three cells showing suppression by L-NOArg. In ten cells the effect of the soluble analogue of cGMP, 8-bromo-cGMP, was tested. In three of those in which L-NOArg application reduced firing, 8-bromo-cGMP had an excitatory effect. In six out of fifteen cells tested, L-NOArg non-selectively reduced responses to NMDA and alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid (AMPA). Again, co-application of L-Arg reversed this effect, without enhancing activity beyond control values. 3. In a further subpopulation of ten cells, L-NOArg decreased responses to ACh in five. 4. In four out of twenty-nine cells L-NOArg produced the opposite effect and increased visual responses. This was reversed by co-application of L-Arg. Some cells were also affected by 8-bromo-cGMP and DEA-NO in ways opposite to those described above. It is possible that the variety of effects seen here could also reflect trans-synaptic activation, or changes in local circuit activity. However, the most parsimonious explanation for our data is that NO differentially affects the activity of two populations of cortical cells, in the main causing a non-specific excitation.

  7. Actions of compounds manipulating the nitric oxide system in the cat primary visual cortex.

    PubMed Central

    Cudeiro, J; Rivadulla, C; Rodríguez, R; Grieve, K L; Martínez-Conde, S; Acuña, C

    1997-01-01

    1. We iontophoretically applied NG-nitro-L-arginine (L-NOArg), an inhibitor of nitric oxide synthase (NOS), to cells (n = 77) in area 17 of anaesthetized and paralysed cats while recording single-unit activity extracellularly. In twenty-nine out of seventy-seven cells (38%), compounds altering NO levels affected visual responses. 2. In twenty-five out of twenty-nine cells, L-NOArg non-selectively reduced visually elicited responses and spontaneous activity. These effects were reversed by co-application of L-arginine (L-Arg), which was without effect when applied alone. Application of the NO donor diethylamine-nitric oxide (DEA-NO) produced excitation in three out of eleven cells, all three cells showing suppression by L-NOArg. In ten cells the effect of the soluble analogue of cGMP, 8-bromo-cGMP, was tested. In three of those in which L-NOArg application reduced firing, 8-bromo-cGMP had an excitatory effect. In six out of fifteen cells tested, L-NOArg non-selectively reduced responses to NMDA and alpha-amino-3-hydroxy-5-methylisoxasole-4-propionic acid (AMPA). Again, co-application of L-Arg reversed this effect, without enhancing activity beyond control values. 3. In a further subpopulation of ten cells, L-NOArg decreased responses to ACh in five. 4. In four out of twenty-nine cells L-NOArg produced the opposite effect and increased visual responses. This was reversed by co-application of L-Arg. Some cells were also affected by 8-bromo-cGMP and DEA-NO in ways opposite to those described above. It is possible that the variety of effects seen here could also reflect trans-synaptic activation, or changes in local circuit activity. However, the most parsimonious explanation for our data is that NO differentially affects the activity of two populations of cortical cells, in the main causing a non-specific excitation. PMID:9365918

  8. Analysis of neural activity in human motor cortex -- Towards brain machine interface system

    NASA Astrophysics Data System (ADS)

    Secundo, Lavi

    The discovery of directional tuned neurons in the primary motor cortex has advanced motor research in several domains. For instance, in the area of brain machine interface (BMI), researchers have exploited the robust characteristic of tuned motor neurons to allow monkeys to learn control of various machines. In the first chapter of this work we examine whether this phenomena can be observed using the less invasive method of recording electrocorticographic signals (ECoG) from the surface of a human's brain. Our findings reveal that individual ECoG channels contain complex movement information about the neuronal population. While some ECoG channels are tuned to hand movement direction (direction specific channels), others are associated to movement but do not contain information regarding movement direction (non-direction specific channels). More specifically, directionality can vary temporally and by frequency within one channel. In addition, a handful of channels contain no significant information regarding movement at all. These findings strongly suggest that directional and non-directional regions of cortex can be identified with ECoG and provide solutions to decoding movement at the signal resolution provided by ECoG. In the second chapter we examine the influence of movement context on movement reconstruction accuracy. We recorded neuronal signals recorded from electro-corticography (ECoG) during performance of cued- and self-initiated movements. ECoG signals were used to train a reconstruction algorithm to reconstruct continuous hand movement. We found that both cued- and self-initiated movements could be reconstructed with similar accuracy from the ECoG data. However, while an algorithm trained on the cued task could reconstruct performance on a subsequent cued trial, it failed to reconstruct self-initiated arm movement. The same task-specificity was observed when the algorithm was trained with self-initiated movement data and tested on the cued task. Thus

  9. Influence of COPD Assessment Text (CAT) evaluation and rehabilitation education guidance on the respiratory and motor functions of COPD patients

    PubMed Central

    Liu, Jing; Meng, Guangju; Ma, Yi; Zhang, Xia; Chen, Dongmei; Chen, Mengting

    2015-01-01

    The study aimed to evaluate the influence of the COPD Assessment Test (CAT) evaluation and rehabilitation education guidance on the respiratory and motor functions of patients with chronic obstructive pulmonary disease (COPD). Forty-five patients with COPD admitted from Nov. 2012 to Nov. 2013 were treated with combined bronchodilators and inhaled corticosteroids. Thirty-five patients admitted from Nov. 2012 to Nov. 2013 and classified as a study group received rehabilitation education guidance on the basis of the treatment of the control group to compare the quality-of-life-scale score, dyspnea index score, and motor function of the two groups of patients after 48 weeks of treatment. After treatment, the CAT score of both groups of patients was significantly lowered. After 48 weeks of treatment, the respiratory function of both groups was significantly improved, but the Medical Research Council (MRC) scale for the study group after treatment was significantly lower than that for the control group. After 48 weeks of rehabilitation exercises, the 6-minute walk test (6MWT) for patients with COPD was significantly prolonged, but the test results were significantly higher for the study group after treatment than for the control group. After receiving CAT rehabilitation education, COPD patients had significantly improved life quality and significantly enhanced exercise tolerance. The treatment mode may be gradually introduced in future clinic and nursing work. PMID:28352725

  10. Influence of position and stimulation parameters on intracortical inhibition and facilitation in human tongue motor cortex.

    PubMed

    Kothari, Mohit; Svensson, Peter; Nielsen, Jørgen Feldbæk; Baad-Hansen, Lene

    2014-04-04

    Paired-pulse transcranial magnetic stimulation (ppTMS) can be used to assess short-interval intracortical inhibitory (SICI) and facilitatory (ICF) networks. Many methodological parameters may however influence the outcome. The aim of the study was to examine the influence of body positions (recline and supine), inter-stimulus intervals (ISI) between the test stimulus (TS) and conditioning stimulus (CS) and intensities of the TS and CS on the degree of SICI and ICF. In studies 1 and 2, fourteen and seventeen healthy volunteers participated respectively. ppTMS was applied over the "hot-spot" of the tongue motor cortex and motor evoked potentials (MEPs) were recorded from contralateral tongue muscles. In study 1, single pulse and three ppTMS ISIs, 2, 10, and 15ms, were applied 8 times each in three blocks (TS: 120%, 140% and 160% of resting motor threshold (rMT); CS: 80% of rMT) in two different body positions (recline and supine) randomly. In study 2, single pulse and four ppTMS ISIs, 2, 2.5, 3, and 3.5ms, were applied 8 times each in randomized order in two blocks (CS: 70% and 80% of rMT; TS: 120% of rMT). There was a significant effect of body position (P=0.049), TS intensities (P<0.001) and ISIs (P<0.001) and interaction between intensity and ISIs (P=0.042) in study 1. In study 2, there was a significant effect of ISI (P<0.001) but not CS intensity (P=0.984) on MEP amplitude. These results may be applied in future studies on the mechanisms of cortical plasticity in the tongue motor pathways using ppTMS and SICI and ICF.

  11. On the functional organization and operational principles of the motor cortex

    PubMed Central

    Capaday, Charles; Ethier, Christian; Van Vreeswijk, Carl; Darling, Warren G.

    2013-01-01

    Recent studies on the functional organization and operational principles of the motor cortex (MCx), taken together, strongly support the notion that the MCx controls the muscle synergies subserving movements in an integrated manner. For example, during pointing the shoulder, elbow and wrist muscles appear to be controlled as a coupled functional system, rather than singly and separately. The recurrent pattern of intrinsic synaptic connections between motor cortical points is likely part of the explanation for this operational principle. So too is the reduplicated, non-contiguous and intermingled representation of muscles in the MCx. A key question addressed in this article is whether the selection of movement related muscle synergies is a dynamic process involving the moment to moment functional linking of a variety of motor cortical points, or rather the selection of fixed patterns embedded in the MCx circuitry. It will be suggested that both operational principles are probably involved. We also discuss the neural mechanisms by which cortical points may be dynamically linked to synthesize movement related muscle synergies. Separate corticospinal outputs sum linearly and lead to a blending of the movements evoked by activation of each point on its own. This operational principle may simplify the synthesis of motor commands. We will discuss two possible mechanisms that may explain linear summation of outputs. We have observed that the final posture of the arm when pointing to a given spatial location is relatively independent of its starting posture. From this observation and the recurrent nature of the MCx intrinsic connectivity we hypothesize that the basic mode of operation of the MCx is to associate spatial location to final arm posture. We explain how the recurrent network connectivity operates to generate the muscle activation patterns (synergies) required to move the arm and hold it in its final position. PMID:23616749

  12. Reappraisal of field dynamics of motor cortex during self-paced finger movements

    PubMed Central

    Suzuki, Masataka; Wasaka, Toshiaki; Inui, Koji; Kakigi, Ryusuke

    2013-01-01

    Background The exact origin of neuronal responses in the human sensorimotor cortex subserving the generation of voluntary movements remains unclear, despite the presence of characteristic but robust waveforms in the records of electroencephalography or magnetoencephalography (MEG). Aims To clarify this fundamental and important problem, we analyzed MEG in more detail using a multidipole model during pulsatile extension of the index finger, and made some important new findings. Results Movement-related cerebral fields (MRCFs) were confirmed over the sensorimotor region contralateral to the movement, consisting of a temporal succession of the first premovement component termed motor field, followed by two or three postmovement components termed movement evoked fields. A source analysis was applied to separately model each of these field components. Equivalent current diploes of all components of MRCFs were estimated to be located in the same precentral motor region, and did not differ with respect to their locations and orientations. The somatosensory evoked fields following median nerve stimulation were used to validate these findings through comparisons of the location and orientation of composite sources with those specified in MRCFs. The sources for the earliest components were evoked in Brodmann's area 3b located lateral to the sources of MRCFs, and those for subsequent components in area 5 and the secondary somatosensory area were located posterior to and inferior to the sources of MRCFs, respectively. Another component peaking at a comparable latency with the area 3b source was identified in the precentral motor region where all sources of MRCFs were located. Conclusion These results suggest that the MRCF waveform reflects a series of responses originating in the precentral motor area. PMID:24363977

  13. Reinforcement learning of targeted movement in a spiking neuronal model of motor cortex.

    PubMed

    Chadderdon, George L; Neymotin, Samuel A; Kerr, Cliff C; Lytton, William W

    2012-01-01

    Sensorimotor control has traditionally been considered from a control theory perspective, without relation to neurobiology. In contrast, here we utilized a spiking-neuron model of motor cortex and trained it to perform a simple movement task, which consisted of rotating a single-joint "forearm" to a target. Learning was based on a reinforcement mechanism analogous to that of the dopamine system. This provided a global reward or punishment signal in response to decreasing or increasing distance from hand to target, respectively. Output was partially driven by Poisson motor babbling, creating stochastic movements that could then be shaped by learning. The virtual forearm consisted of a single segment rotated around an elbow joint, controlled by flexor and extensor muscles. The model consisted of 144 excitatory and 64 inhibitory event-based neurons, each with AMPA, NMDA, and GABA synapses. Proprioceptive cell input to this model encoded the 2 muscle lengths. Plasticity was only enabled in feedforward connections between input and output excitatory units, using spike-timing-dependent eligibility traces for synaptic credit or blame assignment. Learning resulted from a global 3-valued signal: reward (+1), no learning (0), or punishment (-1), corresponding to phasic increases, lack of change, or phasic decreases of dopaminergic cell firing, respectively. Successful learning only occurred when both reward and punishment were enabled. In this case, 5 target angles were learned successfully within 180 s of simulation time, with a median error of 8 degrees. Motor babbling allowed exploratory learning, but decreased the stability of the learned behavior, since the hand continued moving after reaching the target. Our model demonstrated that a global reinforcement signal, coupled with eligibility traces for synaptic plasticity, can train a spiking sensorimotor network to perform goal-directed motor behavior.

  14. Reinforcement Learning of Targeted Movement in a Spiking Neuronal Model of Motor Cortex

    PubMed Central

    Chadderdon, George L.; Neymotin, Samuel A.; Kerr, Cliff C.; Lytton, William W.

    2012-01-01

    Sensorimotor control has traditionally been considered from a control theory perspective, without relation to neurobiology. In contrast, here we utilized a spiking-neuron model of motor cortex and trained it to perform a simple movement task, which consisted of rotating a single-joint “forearm” to a target. Learning was based on a reinforcement mechanism analogous to that of the dopamine system. This provided a global reward or punishment signal in response to decreasing or increasing distance from hand to target, respectively. Output was partially driven by Poisson motor babbling, creating stochastic movements that could then be shaped by learning. The virtual forearm consisted of a single segment rotated around an elbow joint, controlled by flexor and extensor muscles. The model consisted of 144 excitatory and 64 inhibitory event-based neurons, each with AMPA, NMDA, and GABA synapses. Proprioceptive cell input to this model encoded the 2 muscle lengths. Plasticity was only enabled in feedforward connections between input and output excitatory units, using spike-timing-dependent eligibility traces for synaptic credit or blame assignment. Learning resulted from a global 3-valued signal: reward (+1), no learning (0), or punishment (−1), corresponding to phasic increases, lack of change, or phasic decreases of dopaminergic cell firing, respectively. Successful learning only occurred when both reward and punishment were enabled. In this case, 5 target angles were learned successfully within 180 s of simulation time, with a median error of 8 degrees. Motor babbling allowed exploratory learning, but decreased the stability of the learned behavior, since the hand continued moving after reaching the target. Our model demonstrated that a global reinforcement signal, coupled with eligibility traces for synaptic plasticity, can train a spiking sensorimotor network to perform goal-directed motor behavior. PMID:23094042

  15. Spontaneous ventilation and respiratory motor output during carbachol-induced atonia of REM sleep in the decerebrate cat.

    PubMed

    Tojima, H; Kubin, L; Kimura, H; Davies, R O

    1992-10-01

    Microinjections of carbachol into the pons induce a state that resembles rapid eye movement (REM) sleep in intact cats and, in decerebrate, artificially ventilated cats, produce postural atonia accompanied by a powerful depression of the respiratory motor output. In this study, pontine carbachol was used in decerebrate, spontaneously breathing cats to assess the effects of mechanical and chemical respiratory reflexes on the magnitude and pattern of the carbachol-induced depression of breathing, and to determine whether the depression is altered in those animals in which rapid eye movements are present. Phrenic nerve activity and tidal volume were only transiently depressed at the onset of the carbachol-induced postural atonia, whereas the decrease in respiratory rate and the depressions of hypoglossal and intercostal activities persisted until the response was reversed by a pontine microinjection of atropine 15-101 minutes after the onset of carbachol response. Ventilation was reduced to 70% of control during the steady-state conditions. The irregularity of breathing, characterized by the inter-quartile ranges of the distributions of the peak phrenic nerve activity and respiratory timing, did not increase following pontine carbachol. Neither vagotomy nor vigorous eye movements were associated with increased breathing irregularity. This contrasts with the irregular breathing (with minor average changes in ventilation) typical of natural REM sleep. We propose that the carbachol-injected decerebrate cat provides a useful model of the depressant effects that neural events associated with REM sleep may have on breathing.

  16. Mirror illusion reduces motor cortical inhibition in the ipsilateral primary motor cortex during forceful unilateral muscle contractions.

    PubMed

    Zult, Tjerk; Goodall, Stuart; Thomas, Kevin; Hortobágyi, Tibor; Howatson, Glyn

    2015-04-01

    Forceful, unilateral contractions modulate corticomotor paths targeting the resting, contralateral hand. However, it is unknown whether mirror-viewing of a slowly moving but forcefully contracting hand would additionally affect these paths. Here we examined corticospinal excitability and short-interval intracortical inhibition (SICI) of the right-ipsilateral primary motor cortex (M1) in healthy young adults under no-mirror and mirror conditions at rest and during right wrist flexion at 60% maximal voluntary contraction (MVC). During the no-mirror conditions neither hand was visible, whereas in the mirror conditions participants looked at the right hand's reflection in the mirror. Corticospinal excitability increased during contractions in the left flexor carpi radialis (FCR) (contraction 0.41 mV vs. rest 0.21 mV) and extensor carpi radialis (ECR) (contraction 0.56 mV vs. rest 0.39 mV), but there was no mirror effect (FCR: P = 0.743, ηp (2) = 0.005; ECR: P = 0.712, ηp (2) = 0.005). However, mirror-viewing of the contracting and moving wrist attenuated SICI relative to test pulse in the left FCR by ∼9% compared with the other conditions (P < 0.05, d ≥ 0.62). Electromyographic activity in the resting left hand prior to stimulation was not affected by the mirror (FCR: P = 0.255, ηp (2) = 0.049; ECR: P = 0.343, ηp (2) = 0.035) but increased twofold during contractions. Thus viewing the moving hand in the mirror and not just the mirror image of the nonmoving hand seems to affect motor cortical inhibitory networks in the M1 associated with the mirror image. Future studies should determine whether the use of a mirror could increase interlimb transfer produced by cross-education, especially in patient groups with unilateral orthopedic and neurological conditions.

  17. Neurons in Primary Motor Cortex Encode Hand Orientation in a Reach-to-Grasp Task.

    PubMed

    Ma, Chaolin; Ma, Xuan; Fan, Jing; He, Jiping

    2017-04-07

    It is disputed whether those neurons in the primary motor cortex (M1) that encode hand orientation constitute an independent channel for orientation control in reach-to-grasp behaviors. Here, we trained two monkeys to reach forward and grasp objects positioned in the frontal plane at different orientation angles, and simultaneously recorded the activity of M1 neurons. Among the 2235 neurons recorded in M1, we found that 18.7% had a high correlation exclusively with hand orientation, 15.9% with movement direction, and 29.5% with both movement direction and hand orientation. The distributions of neurons encoding hand orientation and those encoding movement direction were not uniform but coexisted in the same region. The trajectory of hand rotation was reproduced by the firing patterns of the orientation-related neurons independent of the hand reaching direction. These results suggest that hand orientation is an independent component for the control of reaching and grasping activity.

  18. Perirhinal cortex relays auditory information to the frontal motor cortices in the rat.

    PubMed

    Kyuhou, Shin-ichi; Matsuzaki, Ryuichi; Gemba, Hisae

    2003-12-26

    Auditory evoked potentials (AEPs) were recorded in the motor cortices (MC) with chronically implanted electrodes in the rat. Some of the AEPs in the MC, namely negative potentials on the surface and positive ones at a depth of 2 mm at latencies of about 50-150 ms, were abolished by limited bilateral lesions of the anterior perirhinal cortex (PERa) which was responsive to auditory stimulus, indicating that the AEPs in the MC were at least partially relayed in the PERa. The auditory response in the MC was prominently enhanced when water was supplied or the medial forebrain bundle was stimulated after auditory stimulus. These results indicate that the MC receives the reward associated auditory information from the PERa.

  19. Fatigue-induced motor cortex excitability changes in subjects with spinal cord injury.

    PubMed

    Nardone, Raffaele; Höller, Yvonne; Brigo, Francesco; Höller, Peter; Christova, Monica; Tezzon, Frediano; Golaszewski, Stefan; Trinka, Eugen

    2013-10-01

    To further investigate the mechanisms of exercise-induced cortical plasticity after spinal cord injury (SCI), the cortical silent period (CoSP) evoked by transcranial magnetic stimulation (TMS) during a fatiguing muscle contraction was evaluated in 5 patients with incomplete cervical SCI and in 5 healthy subjects. The physiological lengthening of CoSP end latency during fatigue was not observed in the SCI patients. This reduced intracortical inhibition, probably secondary to decreased activity of the GABAergic inhibitory interneurons that modulate the corticomotoneuronal output, could represent a 'positive' neuroplastic response in an attempt to compensate for the loss of corticospinal axons. The investigation of motor cortex excitability during fatiguing exercise may shed light on the role of exercise therapy in promoting brain reorganization and functional recovery in humans.

  20. Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation

    PubMed Central

    Nitsche, M A; Paulus, W

    2000-01-01

    In this paper we demonstrate in the intact human the possibility of a non-invasive modulation of motor cortex excitability by the application of weak direct current through the scalp.Excitability changes of up to 40 %, revealed by transcranial magnetic stimulation, were accomplished and lasted for several minutes after the end of current stimulation.Excitation could be achieved selectively by anodal stimulation, and inhibition by cathodal stimulation.By varying the current intensity and duration, the strength and duration of the after-effects could be controlled.The effects were probably induced by modification of membrane polarisation. Functional alterations related to post-tetanic potentiation, short-term potentiation and processes similar to postexcitatory central inhibition are the likely candidates for the excitability changes after the end of stimulation. Transcranial electrical stimulation using weak current may thus be a promising tool to modulate cerebral excitability in a non-invasive, painless, reversible, selective and focal way. PMID:10990547

  1. Altered Modulation of Silent Period in Tongue Motor Cortex of Persistent Developmental Stuttering in Relation to Stuttering Severity

    PubMed Central

    Busan, Pierpaolo; Del Ben, Giovanni; Bernardini, Simona; Natarelli, Giulia; Bencich, Marco; Monti, Fabrizio; Manganotti, Paolo; Battaglini, Piero Paolo

    2016-01-01

    Motor balance in developmental stuttering (DS) was investigated with Transcranial Magnetic Stimulation (TMS), with the aim to define novel neural markers of persistent DS in adulthood. Eleven DS adult males were evaluated with TMS on tongue primary motor cortex, compared to 15 matched fluent speakers, in a “state” condition (i.e. stutterers vs. fluent speakers, no overt stuttering). Motor and silent period thresholds (SPT), recruitment curves, and silent period durations were acquired by recording tongue motor evoked potentials. Tongue silent period duration was increased in DS, especially in the left hemisphere (P<0.05; Hedge’s g or Cohen’s dunbiased = 1.054, i.e. large effect size), suggesting a “state” condition of higher intracortical inhibition in left motor cortex networks. Differences in motor thresholds (different excitatory/inhibitory ratios in DS) were evident, as well as significant differences in SPT. In fluent speakers, the left hemisphere may be marginally more excitable than the right one in motor thresholds at lower muscular activation, while active motor thresholds and SPT were higher in the left hemisphere of DS with respect to the right one, resulting also in a positive correlation with stuttering severity. Pre-TMS electromyography data gave overlapping evidence. Findings suggest the existence of a complex intracortical balance in DS tongue primary motor cortex, with a particular interplay between excitatory and inhibitory mechanisms, also in neural substrates related to silent periods. Findings are discussed with respect to functional and structural impairments in stuttering, and are also proposed as novel neural markers of a stuttering “state” in persistent DS, helping to define more focused treatments (e.g. neuro-modulation). PMID:27711148

  2. Acute Exposure to Pacific Ciguatoxin Reduces Electroencephalogram Activity and Disrupts Neurotransmitter Metabolic Pathways in Motor Cortex.

    PubMed

    Kumar, Gajendra; Au, Ngan Pan Bennett; Lei, Elva Ngai Yu; Mak, Yim Ling; Chan, Leanne Lai Hang; Lam, Michael Hon Wah; Chan, Leo Lai; Lam, Paul Kwan Sing; Ma, Chi Him Eddie

    2016-09-10

    Ciguatera fish poisoning (CFP) is a common human food poisoning caused by consumption of ciguatoxin (CTX)-contaminated fish affecting over 50,000 people worldwide each year. CTXs are classified depending on their origin from the Pacific (P-CTXs), Indian Ocean (I-CTXs), and Caribbean (C-CTXs). P-CTX-1 is the most toxic CTX known and the major source of CFP causing an array of neurological symptoms. Neurological symptoms in some CFP patients last for several months or years; however, the underlying electrophysiological properties of acute exposure to CTXs remain unknown. Here, we used CTX purified from ciguatera fish sourced in the Pacific Ocean (P-CTX-1). Delta and theta electroencephalography (EEG) activity was reduced remarkably in 2 h and returned to normal in 6 h after a single exposure. However, second exposure to P-CTX-1 induced not only a further reduction in EEG activities but also a 2-week delay in returning to baseline EEG values. Ciguatoxicity was detected in the brain hours after the first and second exposure by mouse neuroblastoma assay. The spontaneous firing rate of single motor cortex neuron was reduced significantly measured by single-unit recording with high spatial resolution. Expression profile study of neurotransmitters using targeted profiling approach based on liquid chromatography-tandem mass spectrometry revealed an imbalance between excitatory and inhibitory neurotransmitters in the motor cortex. Our study provides a possible link between the brain oscillations and neurotransmitter release after acute exposure to P-CTX-1. Identification of EEG signatures and major metabolic pathways affected by P-CTX-1 provides new insight into potential biomarker development and therapeutic interventions.

  3. Coherent oscillations in monkey motor cortex and hand muscle EMG show task-dependent modulation.

    PubMed Central

    Baker, S N; Olivier, E; Lemon, R N

    1997-01-01

    1. Recordings were made of local field potential (slow waves) and pyramidal tract neurone (PTN) discharge from pairs of sites separated by a horizontal distance of up to 1.5 mm in the primary motor cortex of two conscious macaque monkeys performing a precision grip task. 2. In both monkeys, the slow wave recordings showed bursts of oscillations in the 20-30 Hz range. Spectral analysis revealed that the oscillations were coherent between the two simultaneously recorded cortical sites. In the monkey from which most data were recorded, the mean frequency of peak coherence was 23.4 Hz. 3. Coherence in this frequency range was also seen between cortical slow wave recordings and rectified EMG of hand and forearm muscles active during the task, and between pairs of rectified EMGs. 4. The dynamics of the coherence were investigated by analysing short, quasi-stationary data segments aligned relative to task performance. This revealed that the 20-30 Hz coherent oscillations were present mainly during the hold phase of the precision grip task. 5. The spikes of identified PTNs were used to compile spike-triggered averages of the slow wave recordings. Oscillations were seen in 11/17 averages of the slow wave recorded on the same electrode as the triggering spike, and 11/17 averages of the slow wave recorded on the distant electrode. The mean period of these oscillations was 45.8 ms. 6. It is concluded that oscillations in the range 20-30 Hz are present in monkey motor cortex, are coherent between spatially separated cortical sites, and encompass the pyramidal tract output neurones. They are discernable in the EMG of active muscles, and show a consistent task-dependent modulation. Images Figure 3 Figure 6 Figure 7 PMID:9175005

  4. Early hypersynchrony in juvenile PINK1−/− motor cortex is rescued by antidromic stimulation

    PubMed Central

    Carron, Romain; Filipchuk, Anton; Nardou, Romain; Singh, Abhinav; Michel, Francois J.; Humphries, Mark D.; Hammond, Constance

    2014-01-01

    In Parkinson’s disease (PD), cortical networks show enhanced synchronized activity but whether this precedes motor signs is unknown. We investigated this question in PINK1−/− mice, a genetic rodent model of the PARK6 variant of familial PD which shows impaired spontaneous locomotion at 16 months. We used two-photon calcium imaging and whole-cell patch clamp in slices from juvenile (P14–P21) wild-type or PINK1−/− mice. We designed a horizontal tilted cortico-subthalamic slice where the only connection between cortex and subthalamic nucleus (STN) is the hyperdirect cortico-subthalamic pathway. We report excessive correlation and synchronization in PINK1−/− M1 cortical networks 15 months before motor impairment. The percentage of correlated pairs of neurons and their strength of correlation were higher in the PINK1−/− M1 than in the wild type network and the synchronized network events involved a higher percentage of neurons. Both features were independent of thalamo-cortical pathways, insensitive to chronic levodopa treatment of pups, but totally reversed by antidromic invasion of M1 pyramidal neurons by axonal spikes evoked by high frequency stimulation (HFS) of the STN. Our study describes an early excess of synchronization in the PINK1−/− cortex and suggests a potential role of antidromic activation of cortical interneurons in network desynchronization. Such backward effect on interneurons activity may be of importance for HFS-induced network desynchronization. PMID:24904316

  5. Primary motor cortex of the parkinsonian monkey: altered encoding of active movement

    PubMed Central

    Pasquereau, Benjamin; DeLong, Mahlon R.

    2016-01-01

    Abnormalities in the movement-related activation of the primary motor cortex (M1) are thought to be a major contributor to the motor signs of Parkinson’s disease. The existing evidence, however, variably indicates that M1 is under-activated with movement, overactivated (due to a loss of functional specificity) or activated with abnormal timing. In addition, few models consider the possibility that distinct cortical neuron subtypes may be affected differently. Those gaps in knowledge were addressed by studying the extracellular activity of antidromically-identified lamina 5b pyramidal-tract type neurons (n = 153) and intratelencephalic-type corticostriatal neurons (n = 126) in the M1 of two monkeys as they performed a step-tracking arm movement task. We compared movement-related discharge before and after the induction of parkinsonism by administration of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) and quantified the spike rate encoding of specific kinematic parameters of movement using a generalized linear model. The fraction of M1 neurons with movement-related activity declined following MPTP but only marginally. The strength of neuronal encoding of parameters of movement was reduced markedly (mean 29% reduction in the coefficients from the generalized linear model). This relative decoupling of M1 activity from kinematics was attributable to reductions in the coefficients that estimated the spike rate encoding of movement direction (−22%), speed (−40%), acceleration (−49%) and hand position (−33%). After controlling for MPTP-induced changes in motor performance, M1 activity related to movement itself was reduced markedly (mean 36% hypoactivation). This reduced activation was strong in pyramidal tract-type neurons (−50%) but essentially absent in corticostriatal neurons. The timing of M1 activation was also abnormal, with earlier onset times, prolonged response durations, and a 43% reduction in the prevalence of movement-related changes

  6. Abnormal reactivity of the approximately 20-Hz motor cortex rhythm in Unverricht Lundborg type progressive myoclonus epilepsy.

    PubMed

    Silén, T; Forss, N; Jensen, O; Hari, R

    2000-12-01

    The approximately 20-Hz component of the human mu rhythm originates predominantly in the primary motor cortex. We monitored with a whole-scalp neuromagnetometer the reactivity of the approximately 20-Hz rhythm as an index of the functional state of the primary motor cortex in seven patients suffering from Unverricht-Lundborg type (ULD) progressive myoclonus epilepsy (PME) and in seven healthy control subjects. In patients, the motor cortex rhythm was on average 5 Hz lower in frequency and its strength was double compared with controls. To study reactivity of the approximately 20-Hz rhythm, left and right median nerves were stimulated alternately at wrists. In controls, these stimuli elicited a small transient decrease, followed by a strong increase ("rebound") of the approximately 20-Hz level. In contrast, the patients showed no significant rebounds of the rhythm. As the approximately 20-Hz rebounds apparently reflect increased cortical inhibition, our results indicate that peripheral stimuli excite motor cortex for prolonged periods in patients with ULD.

  7. The Contribution of Primary Motor Cortex Is Essential for Probabilistic Implicit Sequence Learning: Evidence from Theta Burst Magnetic Stimulation

    ERIC Educational Resources Information Center

    Wilkinson, Leonora; Teo, James T.; Obeso, Ignacio; Rothwell, John C.; Jahanshahi, Marjan

    2010-01-01

    Theta burst transcranial magnetic stimulation (TBS) is considered to produce plastic changes in human motor cortex. Here, we examined the inhibitory and excitatory effects of TBS on implicit sequence learning using a probabilistic serial reaction time paradigm. We investigated the involvement of several cortical regions associated with implicit…

  8. Overlapping representations of the neck and whiskers in the rat motor cortex revealed by mapping at different anaesthetic depths

    PubMed Central

    Tandon, Shashank; Kambi, Niranjan; Jain, Neeraj

    2008-01-01

    The primary motor cortex of mammals has an orderly representation of different body parts. Within the representation of each body part the organization is more complex, with groups of neurons representing movements of a muscle or a group of muscles. In rats, uncertainties continue to exist regarding organization of the primary motor cortex in the whisker and the neck region. Using intracortical microstimulation (ICMS) we show that movements evoked in the whisker and the neck region of the rat motor cortex are highly sensitive to the depth of anaesthesia. At light anaesthetic depth, whisker movements are readily evoked from a large medial region of the motor cortex. Lateral to this is a small region where movements of the neck are evoked. However, in animals under deep anaesthesia whisker movements cannot be evoked. Instead, neck movements are evoked from this region. The neck movement region thus becomes greatly expanded. An analysis of the threshold currents required to evoke movements at different anaesthetic depths reveals that the caudal portion of the whisker region has dual representation, of both the whisker and the neck movements. The results also underline the importance of carefully controlling the depth of anaesthesia during ICMS experiments. PMID:18093166

  9. The Largest Response Component in the Motor Cortex Reflects Movement Timing but Not Movement Type

    PubMed Central

    Sussillo, David; Ryu, Stephen I.

    2016-01-01

    Abstract Neural activity in monkey motor cortex (M1) and dorsal premotor cortex (PMd) can reflect a chosen movement well before that movement begins. The pattern of neural activity then changes profoundly just before movement onset. We considered the prediction, derived from formal considerations, that the transition from preparation to movement might be accompanied by a large overall change in the neural state that reflects when movement is made rather than which movement is made. Specifically, we examined “components” of the population response: time-varying patterns of activity from which each neuron’s response is approximately composed. Amid the response complexity of individual M1 and PMd neurons, we identified robust response components that were “condition-invariant”: their magnitude and time course were nearly identical regardless of reach direction or path. These condition-invariant response components occupied dimensions orthogonal to those occupied by the “tuned” response components. The largest condition-invariant component was much larger than any of the tuned components; i.e., it explained more of the structure in individual-neuron responses. This condition-invariant response component underwent a rapid change before movement onset. The timing of that change predicted most of the trial-by-trial variance in reaction time. Thus, although individual M1 and PMd neurons essentially always reflected which movement was made, the largest component of the population response reflected movement timing rather than movement type. PMID:27761519

  10. Differential representation of spectral and temporal information by primary auditory cortex neurons in awake cats: relevance to auditory scene analysis.

    PubMed

    Sakai, Masashi; Chimoto, Sohei; Qin, Ling; Sato, Yu

    2009-04-10

    We investigated how the primary auditory cortex (AI) neurons encode the two major requisites for auditory scene analysis, i.e., spectral and temporal information. Single-unit activities in awake cats AI were studied by presenting 0.5-s-long tone bursts and click trains. First of all, the neurons (n=92) were classified into 3 types based on the time-course of excitatory responses to tone bursts: 1) phasic cells (P-cells; 26%), giving only transient responses; 2) tonic cells (T-cells; 34%), giving sustained responses with little or no adaptation; and 3) phasic-tonic cells (PT-cells; 40%), giving sustained responses with some tendency of adaptation. Other tone-response variables differed among cell types. For example, P-cells showed the shortest latency and smallest spiking jitter while T-cells had the sharpest frequency tuning. PT-cells generally fell in the intermediate between the two extremes. Click trains also revealed between-neuron-type differences for the emergent probability of excitatory responses (P-cells>PT-cells>T-cells) and their temporal features. For example, a substantial fraction of P-cells conducted stimulus-locking responses, but none of the T-cells did. f(r)-dependency characteristics of the stimulus locking resembled that reported for "comodulation masking release," a behavioral model of auditory scene analysis. Each type neurons were omnipresent throughout the AI and none of them showed intrinsic oscillation. These findings suggest that: 1) T-cells preferentially encode spectral information with a rate-place code and 2) P-cells preferentially encode acoustic transients with a temporal code whereby rate-place coded information is potentially bound for scene analysis.

  11. Microtopography of the dual corticothalamic projections originating from domains along the frequency axis of the cat primary auditory cortex.

    PubMed

    Takayanagi, M; Ojima, H

    2006-10-27

    Spatial relationships between clusters of corticothalamic (CT) large terminals originating from cortical domains tuned to different frequencies were examined by pair-injecting two different anterograde tracers. Large-terminal CT projection originating from layer 5 was highly divergent with each injection site producing, on average, 15 local clusters distributing throughout non-lemniscal thalamic nuclei following a single anterograde tracer injection in the cat primary auditory cortex. Paired injections in higher- and lower-frequency cortical domains, resulting in labeling of two independent sets of terminal clusters, showed five recognizable patterns of spatial interaction between them. (1) In the ventral division of the medial geniculate complex (vMGC), sheet-like plexuses of small terminals of different origins were situated in parallel, with minimal overlap. (2) Extensive overlap of two low-density plexuses of differently labeled small terminals was observed in the medial division of the medial geniculate complex (MGC). (3) At the transition zones between the vMGC and the superficial dorsal nucleus of the MGC dorsal division, and between the vMGC and the ventrolateral nucleus, there were relatively broad clusters of a high density of large-terminal structures from the two cortical domains, which overlapped extensively. (4) At multiple loci in the nonlemniscal nuclei, pairing of two small clusters of differently labeled large terminals was observed. (5) Small unpaired clusters of large terminals were also found in the nonlemniscal nuclei. For large terminals, approximately 14%, 59%, and 27% clusters per injection demonstrated patterns 3, 4, and 5, respectively. The results provide evidence for the precise topographical organization for the large-terminal CT system at the microscopic level despite its highly divergent projection. This microtopographical projection from the tonotopic cortical field to non-tonotopic thalamic nuclei may raise the possibility of

  12. High-frequency stimulation of the ventrolateral thalamus regulates gene expression in hippocampus, motor cortex and caudate-putamen.

    PubMed

    Kádár, Elisabeth; Lim, Lee Wei; Carreras, Gemma; Genís, David; Temel, Yasin; Huguet, Gemma

    2011-05-19

    High-frequency stimulation (HFS) of the ventrolateral (VL) thalamus is effective in treating the resting tremor of Parkinson's disease (PD). PD is a movement disorder that involves neurodegeneration, predominantly of the substantia nigra, but also in other brain areas, such as the motor cortex and hippocampus. The mechanisms of action of HFS on remote brain areas at the molecular level are largely unknown. Here, we investigated gene expression profiles using oligonucleotide microarrays and quantitative real-time PCR in rat hippocampi. We showed that chronic (14days) HFS modulates the expression of 176 hippocampal genes. Our results showed that genes involved in proliferation and neurogenesis-related biological functions were specifically regulated by HFS, including nestin (Nes) and doublecortin (Dcx), which are expressed in neural progenitor cells and immature neurons, respectively, as well as genes encoding proteins that may support neural differentiation or migration, such as Timp1, Ccl2, S100a4 and Angpt2. Next, we used quantitative real-time PCR (RT-PCR) to profile these six genes in the motor cortex and the caudate-putamen, which included the subventricular zone (CPu-SVZ). Interestingly, HFS increased Dcx expression in the motor cortex whereas Nes was upregulated in the CPu-SVZ but not in the motor cortex. In the CPu-SVZ Timp1 and Ccl2 were highly upregulated by HFS. In conclusion, our findings suggest that HFS may enhance neuroplasticity at the molecular level in several remote brain areas such as the CPu-SVZ, motor cortex and hippocampus.

  13. An improvement in perception of self-generated tactile stimuli following theta-burst stimulation of primary motor cortex

    PubMed Central

    Voss, Martin; Bays, Paul M.; Rothwell, John C.; Wolpert, Daniel M.

    2007-01-01

    Recent studies have shown that self-generated tactile sensations are perceived as weaker than the same sensations externally generated. This has been linked to a central comparator mechanism that uses efference copy to attenuate the predictable component of sensory inputs arising from one's own actions in order to enhance the salience of external stimuli. To provide a quantitative measure of this attenuation, a force-matching task was developed in which subjects experience a force applied to their finger and are then required to match the perceived force by actively pushing on the finger using their other hand. The attenuation of predictable sensory input results in subjects producing a larger active force than was experienced passively. Here, we have examined the effects of a novel rTMS protocol, theta-burst stimulation (TBS), over primary motor cortex on this attenuation. TBS can alter the excitability of motor cortex to incoming activity. We show that application of a 20 s continuous train of TBS, that depresses motor cortex, significantly improves performance in a force-matching task. This suggests that the TBS intervention disturbed the predictive process that uses efference copy signals to attenuate predictable sensory input. A possible explanation for the effect is that TBS has a differential effect on the populations of neurones that generate motor output in M1 than on those neural structures that are involved in generating an efference copy of the motor command. PMID:17560617

  14. Assistive technology and robotic control using motor cortex ensemble-based neural interface systems in humans with tetraplegia

    PubMed Central

    Donoghue, John P; Nurmikko, Arto; Black, Michael; Hochberg, Leigh R

    2007-01-01

    This review describes the rationale, early stage development, and initial human application of neural interface systems (NISs) for humans with paralysis. NISs are emerging medical devices designed to allow persons with paralysis to operate assistive technologies or to reanimate muscles based upon a command signal that is obtained directly from the brain. Such systems require the development of sensors to detect brain signals, decoders to transform neural activity signals into a useful command, and an interface for the user. We review initial pilot trial results of an NIS that is based on an intracortical microelectrode sensor that derives control signals from the motor cortex. We review recent findings showing, first, that neurons engaged by movement intentions persist in motor cortex years after injury or disease to the motor system, and second, that signals derived from motor cortex can be used by persons with paralysis to operate a range of devices. We suggest that, with further development, this form of NIS holds promise as a useful new neurotechnology for those with limited motor function or communication. We also discuss the additional potential for neural sensors to be used in the diagnosis and management of various neurological conditions and as a new way to learn about human brain function. PMID:17272345

  15. Modulation of motor cortex excitability by peripheral magnetic stimulation of different stimulus sites and frequencies.

    PubMed

    Sato, A; Liu, X; Torii, T; Iwahashi, M; Iramina, K; Sato, A; Liu, X; Torii, T; Iwahashi, M; Iramina, K; Iwahashi, M; Liu, X; Sato, A; Iramina, K; Torii, T

    2016-08-01

    Peripheral stimulation is known to influence the state of cortical excitability. The purpose of this study is to investigate whether peripheral magnetic stimulation has similar effects on cortical excitability to transcranial magnetic stimulation (TMS). A magnetic stimulator with a flat figure-of-eight coil was used for both TMS, and peripheral magnetic stimulation applied to the bilateral forearms. TMS was performed on the left primary motor cortex to evaluate influence of the peripheral magnetic stimulation, and motor evoked potential (MEP) was measured from the right first dorsal interosseous. Peripheral magnetic stimulation was performed at a stimulus frequency of 1 Hz or 10 Hz, to the stimulus sites on the right and left supination of the forearm. The effects of peripheral magnetic stimulation were evaluated by comparing the mean MEP amplitude elicited by TMS before and after peripheral magnetic stimulation. We found that cortical excitability varied according to the stimulation site and frequency of the peripheral magnetic stimulation. The inhibition of cortical excitability was observed following 1 Hz peripheral magnetic stimulation over the right forearm (p<;0.001). In contrast, increased cortical excitability was observed using 1 Hz peripheral magnetic stimulation over the left forearm and 10 Hz stimulation over either the right or left forearms. We suggest that peripheral magnetic stimulation has a similar effect to TMS, and can induce both facilitation and inhibition of cortical excitability.

  16. Evaluation of the Cortical Silent Period of the Laryngeal Motor Cortex in Healthy Individuals

    PubMed Central

    Chen, Mo; Summers, Rebekah L. S.; Goding, George S.; Samargia, Sharyl; Ludlow, Christy L.; Prudente, Cecília N.; Kimberley, Teresa J.

    2017-01-01

    Objective: This work aimed to evaluate the cortical silent period (cSP) of the laryngeal motor cortex (LMC) using the bilateral thyroarytenoid (TA) muscles with transcranial magnetic stimulation (TMS). Methods: In 11 healthy participants, fine-wire electromyography (EMG) was used to record bilateral TA muscle responses to single pulse TMS delivered to the LMC in both hemispheres. Peripheral responses to stimulation over the mastoid, where the vagus nerve exits the skull, were collected to verify the central origin of the cortical stimulation responses by comparing the latencies. Results: The cSP duration ranged from 41.7 to 66.4 ms. The peripherally evoked motor-evoked potential (MEP) peak occurred 5–9 ms earlier than the cortical responses (for both sides of TAs: p < 0.0001) with no silent period. The right TA MEP latencies were earlier than the left TA responses for both peripheral and cortical measures (p ≤ 0.0001). Conclusion: These findings demonstrate the feasibility of measuring cSP of LMC based on intrinsic laryngeal muscles responses during vocalization in healthy volunteers. Significance: The technique could be used to study the pathophysiology of neurological disorders that affect TA muscles, such as spasmodic dysphonia. Further, the methodology has application to other muscles of the head and neck not accessible using surface electrodes. PMID:28326007

  17. Vacillation, indecision and hesitation in moment-by-moment decoding of monkey motor cortex

    PubMed Central

    Kaufman, Matthew T; Churchland, Mark M; Ryu, Stephen I; Shenoy, Krishna V

    2015-01-01

    When choosing actions, we can act decisively, vacillate, or suffer momentary indecision. Studying how individual decisions unfold requires moment-by-moment readouts of brain state. Here we provide such a view from dorsal premotor and primary motor cortex. Two monkeys performed a novel decision task while we recorded from many neurons simultaneously. We found that a decoder trained using ‘forced choices’ (one target viable) was highly reliable when applied to ‘free choices’. However, during free choices internal events formed three categories. Typically, neural activity was consistent with rapid, unwavering choices. Sometimes, though, we observed presumed ‘changes of mind’: the neural state initially reflected one choice before changing to reflect the final choice. Finally, we observed momentary ‘indecision’: delay forming any clear motor plan. Further, moments of neural indecision accompanied moments of behavioral indecision. Together, these results reveal the rich and diverse set of internal events long suspected to occur during free choice. DOI: http://dx.doi.org/10.7554/eLife.04677.001 PMID:25942352

  18. Precise spike synchronization in monkey motor cortex involved in preparation for movement.

    PubMed

    Grammont, F; Riehle, A

    1999-09-01

    It is commonly accepted that perceptually and behaviorally relevant events are reflected in changes of activity in largely distributed neuronal populations. However, it is much less clear how these populations organize dynamically to cope with momentary computational demands. In order to decipher the dynamic organization of cortical ensembles, the activities of up to seven neurons of the primary motor cortex were recorded simultaneously. A monkey was trained to perform a pointing task in six directions. During each trial, two signals were presented consecutively. The first signal provided prior information about the movement direction, whereas the second called for the execution of that movement. Dynamic interactions between the activity of simultaneously recorded neurons were studied by analyzing individual epochs of synchronized firing ("unitary events"). Unitary events were defined as synchronizations which occur significantly more often than expected by chance on the basis of the neurons' firing rates. The aim of the study was to describe the relationships between synchronization dynamics and changes in activity of the same neurons during the preparation and execution of voluntary movements. The data show that even neurons which were classified, on the basis of the change in their firing rate, to be functionally involved in different processes (e.g., preparation or execution related, different directional tuning) synchronized their spiking activity significantly. These findings indicate that the synchronization of individual action potentials and the modulation of the firing rate may serve different and complementary functions underlying the cortical organization of cognitive motor processes.

  19. Beta oscillations reflect changes in motor cortex inhibition in healthy ageing.

    PubMed

    Rossiter, Holly E; Davis, Emma M; Clark, Ella V; Boudrias, Marie-Hélène; Ward, Nick S

    2014-05-01

    Beta oscillations are involved in movement and have previously been linked to levels of the inhibitory neurotransmitter GABA. We examined changes in beta oscillations during rest and movement in primary motor cortex (M1). Amplitude and frequency of beta power at rest and movement-related beta desynchronization (MRBD) were measured during a simple unimanual grip task and their relationship with age was explored in a group of healthy participants. We were able to show that at rest, increasing age was associated with greater baseline beta power in M1 contralateral to the active hand, with a similar (non-significant) trend in ipsilateral M1. During movement, increasing age was associated with increased MRBD amplitude in ipsilateral M1 and reduced frequency (in contralateral and ipsilateral M1). These findings would be consistent with greater GABAergic inhibitory activity within motor cortices of older subjects. These oscillatory parameters have the potential to reveal changes in the excitatory-inhibitory balance in M1 which in turn may be a useful marker of plasticity in the brain, both in healthy ageing and disease.

  20. Double dissociation between motor and visual imagery in the posterior parietal cortex.

    PubMed

    Pelgrims, Barbara; Andres, Michael; Olivier, Etienne

    2009-10-01

    Because motor imagery (MI) and visual imagery (VI) are influenced differently by factors such as biomechanical constraints or stimulus size, it is conceivable that they rely on separate processes, possibly involving distinct cortical networks, a view corroborated by neuroimaging and neuropsychological studies. In the posterior parietal cortex, it has been suggested that the superior parietal lobule (SPL) underlies VI, whereas MI relies on the supramarginalis gyrus (SMG). However, because several brain imaging studies have also shown an overlap of activations in SPL and SMG during VI or MI, the question arises as to which extent these 2 subregions really contribute to distinct imagery processes. To address this issue, we used repetitive transcranial magnetic stimulation to induce virtual lesions of either SMG or SPL in subjects performing a MI (hand drawing rotation) or a VI (letter rotation) task. Whatever hemisphere was stimulated, SMG lesions selectively altered MI, whereas SPL lesions only affected VI, demonstrating a double dissociation between MI and VI. Because these deficits were not influenced by the angular distance of the stimuli, we suggest that SMG and SPL are involved in the reenactment of the motor and visual representations, respectively, and not in mental rotation processes per se.

  1. Automatic motor cortex activation for natural as compared to awkward grips of a manipulable object.

    PubMed

    Petit, Leila S; Pegna, Alan J; Harris, Irina M; Michel, Christoph M

    2006-01-01

    It has been suggested that, relative to natural objects, man-made object representations in the brain are more specifically defined by functional properties that reflect how an object is used and/or what it is used for (Warrington and Shallice 1984). We recorded 123-channel event-related potentials (ERP) in healthy participants during a mental rotation task involving a manipulable (hammer) and a non-manipulable (church) object. Both stimuli had standard and mirror-image versions rotated in four different orientations, resulting for the manipulable object in some natural and some awkward grips. Using spatial cluster analysis, time periods were determined during which the ERP maps differed between stimulus conditions. Specific maps appeared for natural versus awkward grips with the manipulable object at a very early stage (60-116 ms) as well as during a later stage (180-280 ms). Source estimations derived from the topographic data indicated that during the second time window the left motor cortex was significantly activated in the case of natural grips. We argue that the motor programs that are semantically associated with the object are automatically activated when it is presented in graspable orientations.

  2. Reduced functional connectivity within the primary motor cortex of patients with brachial plexus injury.

    PubMed

    Fraiman, D; Miranda, M F; Erthal, F; Buur, P F; Elschot, M; Souza, L; Rombouts, S A R B; Schimmelpenninck, C A; Norris, D G; Malessy, M J A; Galves, A; Vargas, C D

    2016-01-01

    This study aims at the effects of traumatic brachial plexus lesion with root avulsions (BPA) upon the organization of the primary motor cortex (M1). Nine right-handed patients with a right BPA in whom an intercostal to musculocutaneous (ICN-MC) nerve transfer was performed had post-operative resting state fMRI scanning. The analysis of empirical functional correlations between neighboring voxels revealed faster correlation decay as a function of distance in the M1 region corresponding to the arm in BPA patients as compared to the control group. No differences between the two groups were found in the face area. We also investigated whether such larger decay in patients could be attributed to a gray matter diminution in M1. Structural imaging analysis showed no difference in gray matter density between groups. Our findings suggest that the faster decay in neighboring functional correlations without significant gray matter diminution in BPA patients could be related to a reduced activity in intrinsic horizontal connections in M1 responsible for upper limb motor synergies.

  3. Dosage-dependent non-linear effect of L-dopa on human motor cortex plasticity.

    PubMed

    Monte-Silva, Katia; Liebetanz, David; Grundey, Jessica; Paulus, Walter; Nitsche, Michael A

    2010-09-15

    The neuromodulator dopamine affects learning and memory formation and their likely physiological correlates, long-term depression and potentiation, in animals and humans. It is known from animal experiments that dopamine exerts a dosage-dependent, inverted U-shaped effect on these functions. However, this has not been explored in humans so far. In order to reveal a non-linear dose-dependent effect of dopamine on cortical plasticity in humans, we explored the impact of 25, 100 and 200 mg of L-dopa on transcranial direct current (tDCS)-induced plasticity in twelve healthy human subjects. The primary motor cortex served as a model system, and plasticity was monitored by motor evoked potential amplitudes elicited by transcranial magnetic stimulation. As compared to placebo medication, low and high dosages of L-dopa abolished facilitatory as well as inhibitory plasticity, whereas the medium dosage prolonged inhibitory plasticity, and turned facilitatory plasticity into inhibition. Thus the results show clear non-linear, dosage-dependent effects of dopamine on both facilitatory and inhibitory plasticity, and support the assumption of the importance of a specific dosage of dopamine optimally suited to improve plasticity. This might be important for the therapeutic application of dopaminergic agents, especially for rehabilitative purposes, and explain some opposing results in former studies.

  4. Modulation of Training by Single-Session Transcranial Direct Current Stimulation to the Intact Motor Cortex Enhances Motor Skill Acquisition of the Paretic Hand

    PubMed Central

    Zimerman, Máximo; Heise, Kirstin F.; Hoppe, Julia; Cohen, Leonardo G.; Gerloff, Christian; Hummel, Friedhelm C.

    2016-01-01

    Background and Purpose Mechanisms of skill learning are paramount components for stroke recovery. Recent noninvasive brain stimulation studies demonstrated that decreasing activity in the contralesional motor cortex might be beneficial, providing transient functional improvements after stroke. The more crucial question, however, is whether this intervention can also enhance the acquisition of complex motor tasks, yielding longer-lasting functional improvements. In the present study, we tested the capacity of cathodal transcranial direct current stimulation (tDCS) applied over the contralesional motor cortex during training to enhance the acquisition and retention of complex sequential finger movements of the paretic hand. Method Twelve well-recovered chronic patients with subcortical stroke attended 2 training sessions during which either cathodal tDCS or a sham intervention were applied to the contralesional motor cortex in a double-blind, crossover design. Two different motor sequences, matched for their degree of complexity, were tested in a counterbalanced order during as well as 90 minutes and 24 hours after the intervention. Potential underlying mechanisms were evaluated with transcranial magnetic stimulation. Results tDCS facilitated the acquisition of a new motor skill compared with sham stimulation (P=0.04) yielding better task retention results. A significant correlation was observed between the tDCS-induced improvement during training and the tDCS-induced changes of intracortical inhibition (R2=0.63). Conclusions These results indicate that tDCS is a promising tool to improve not only motor behavior, but also procedural learning. They further underline the potential of noninvasive brain stimulation as an adjuvant treatment for long-term recovery, at least in patients with mild functional impairment after stroke. PMID:22618381

  5. A quantitative comparison of the hemispheric, areal, and laminar origins of sensory and motor cortical projections to the superior colliculus of the cat.

    PubMed

    Butler, Blake E; Chabot, Nicole; Lomber, Stephen G

    2016-09-01

    The superior colliculus (SC) is a midbrain structure central to orienting behaviors. The organization of descending projections from sensory cortices to the SC has garnered much attention; however, rarely have projections from multiple modalities been quantified and contrasted, allowing for meaningful conclusions within a single species. Here, we examine corticotectal projections from visual, auditory, somatosensory, motor, and limbic cortices via retrograde pathway tracers injected throughout the superficial and deep layers of the cat SC. As anticipated, the majority of cortical inputs to the SC originate in the visual cortex. In fact, each field implicated in visual orienting behavior makes a substantial projection. Conversely, only one area of the auditory orienting system, the auditory field of the anterior ectosylvian sulcus (fAES), and no area involved in somatosensory orienting, shows significant corticotectal inputs. Although small relative to visual inputs, the projection from the fAES is of particular interest, as it represents the only bilateral cortical input to the SC. This detailed, quantitative study allows for comparison across modalities in an animal that serves as a useful model for both auditory and visual perception. Moreover, the differences in patterns of corticotectal projections between modalities inform the ways in which orienting systems are modulated by cortical feedback. J. Comp. Neurol. 524:2623-2642, 2016. © 2016 Wiley Periodicals, Inc.

  6. Primary motor cortex activity reduction under the regulation of SMA by real-time fMRI

    NASA Astrophysics Data System (ADS)

    Guo, Jia; Zhao, Xiaojie; Li, Yi; Yao, Li; Chen, Kewei

    2012-03-01

    Real-time fMRI (rtfMRI) is a new technology which allows human subjects to observe and control their own BOLD signal change from one or more localized brain regions during scanning. Current rtfMRI-neurofeedback studies mainly focused on the target region itself without considering other related regions influenced by the real-time feedback. However, there always exits important directional influence between many of cooperative regions. On the other hand, rtfMRI based on motor imagery mainly aimed at somatomotor cortex or primary motor area, whereas supplement motor area (SMA) was a relatively more integrated and pivotal region. In this study, we investigated whether the activities of SMA can be controlled utilizing different motor imagery strategies, and whether there exists any possible impact on an unregulated but related region, primary motor cortex (M1). SMA was first localized using overt finger tapping task, the activities of SMA were feedback to subjects visually on line during each of two subsequent imagery motor movement sessions. All thirteen healthy participants were found to be able to successfully control their SMA activities by self-fit imagery strategies which involved no actual motor movements. The activation of right M1 was also found to be significantly reduced in both intensity and extent with the neurofeedback process targeted at SMA, suggestive that not only the part of motor cortex activities were influenced under the regulation of a key region SMA, but also the increased difference between SMA and M1 might reflect the potential learning effect.

  7. [Application of transcranial magnetic stimulation for monitoring of the motor cortex condition in dynamics in healthy subjects].

    PubMed

    Gimranov, R F

    2002-01-01

    Transcranial magnetic stimulation (TMS) is used already for sixteen years for studying human central nervous system. The main objective of this work was to study motor thresholds and their hemispheric asymmetry in healthy subjects during TMS. We examined 31 righthanded healthy students. Their motor thresholds were measured in May (before vacations), September (immediately after vacations), and November (two months after vacations). Magnetic stimulator Neurosoft-MS (Ivanovo, Russia) was used for TNS of the motor cortex. It was shown that in the absence of regular active functional loads on the right hand, the motor thresholds in healthy righthanders significantly increased under the TMS of the left hemisphere, and hemispheric asymmetry disappeared under conditions both of muscle relaxation and voluntary contraction. Motor thresholds under the left-side TMS decreased and hemispheric asymmetry recovered with the restart of the regular active functional loads on the right hand.

  8. COMMUNICATION: On variability and use of rat primary motor cortex responses in behavioral task discrimination

    NASA Astrophysics Data System (ADS)

    Jensen, Winnie; Rousche, Patrick J.

    2006-03-01

    The success of a cortical motor neuroprosthetic system will rely on the system's ability to effectively execute complex motor tasks in a changing environment. Invasive, intra-cortical electrodes have been successfully used to predict joint movement and grip force of a robotic arm/hand with a non-human primate (Chapin J K, Moxon K A, Markowitz R S and Nicolelis M A L 1999 Real-time control of a robotic arm using simultaneously recorded neurons in the motor cortex Nat. Neurosci. 2 664-70). It is well known that cortical encoding occurs with a high degree of cortical plasticity and depends on both the functional and behavioral context. Questions on the expected robustness of future motor prosthesis systems therefore still remain. The objective of the present work was to study the effect of minor changes in functional movement strategies on the M1 encoding. We compared the M1 encoding in freely moving, non-constrained animals that performed two similar behavioral tasks with the same end-goal, and investigated if these behavioral tasks could be discriminated based on the M1 recordings. The rats depressed a response paddle either with a set of restrictive bars ('WB') or without the bars ('WOB') placed in front of the paddle. The WB task required changes in the motor strategy to complete the paddle press and resulted in highly stereotyped movements, whereas in the WOB task the movement strategy was not restricted. Neural population activity was recorded from 16-channel micro-wire arrays and data up to 200 ms before a paddle hit were analyzed off-line. The analysis showed a significant neural firing difference between the two similar WB and WOB tasks, and using principal component analysis it was possible to distinguish between the two tasks with a best classification at 76.6%. While the results are dependent upon a small, randomly sampled neural population, they indicate that information about similar behavioral tasks may be extracted from M1 based on relatively few

  9. Transcranial Direct Current Stimulation of the Motor Cortex Biases Action Choice in a Perceptual Decision Task.

    PubMed

    Javadi, Amir-Homayoun; Beyko, Angeliki; Walsh, Vincent; Kanai, Ryota

    2015-11-01

    One of the multiple interacting systems involved in the selection and execution of voluntary actions is the primary motor cortex (PMC). We aimed to investigate whether the transcranial direct current stimulation (tDCS) of this area can modulate hand choice. A perceptual decision-making task was administered. Participants were asked to classify rectangles with different height-to-width ratios into horizontal and vertical rectangles using their right and left index fingers while their PMC was stimulated either bilaterally or unilaterally. Two experiments were conducted with different stimulation conditions: the first experiment (n = 12) had only one stimulation condition (bilateral stimulation), and the second experiment (n = 45) had three stimulation conditions (bilateral, anodal unilateral, and cathodal unilateral stimulations). The second experiment was designed to confirm the results of the first experiment and to further investigate the effects of anodal and cathodal stimulations alone in the observed effects. Each participant took part in two sessions. The laterality of stimulation was reversed over the two sessions. Our results showed that anodal stimulation of the PMC biases participants' responses toward using the contralateral hand whereas cathodal stimulation biases responses toward the ipsilateral hand. Brain stimulation also modulated the RT of the left hand in all stimulation conditions: Responses were faster when the response bias was in favor of the left hand and slower when the response bias was against it. We propose two possible explanations for these findings: the perceptual bias account (bottom-up effects of stimulation on perception) and the motor-choice bias account (top-down modulation of the decision-making system by facilitation of response in one hand over the other). We conclude that motor responses and the choice of hand can be modulated using tDCS.

  10. Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex

    PubMed Central

    Lu, Yao; Truccolo, Wilson; Wagner, Fabien B.; Vargas-Irwin, Carlos E.; Ozden, Ilker; Zimmermann, Jonas B.; May, Travis; Agha, Naubahar S.; Wang, Jing

    2015-01-01

    Transient gamma-band (40–80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions. PMID:25761956

  11. Dynamical changes and temporal precision of synchronized spiking activity in monkey motor cortex during movement preparation.

    PubMed

    Riehle, A; Grammont, F; Diesmann, M; Grün, S

    2000-01-01

    Movement preparation is considered to be based on central processes which are responsible for improving motor performance. For instance, it has been shown that motor cortical neurones change their activity selectively in relation to prior information about movement parameters. However, it is not clear how groups of neurones dynamically organize their activity to cope with computational demands. The aim of the study was to compare the firing rate of multiple simultaneously recorded neurones with the interaction between them by describing not only the frequency of occurrence of epochs of significant synchronization, but also its modulation in time and its changes in temporal precision during an instructed delay. Multiple single-neurone activity was thus recorded in monkey motor cortex during the performance of two different delayed multi-directional pointing tasks. In order to detect conspicuous spike coincidences in simultaneously recorded spike trains by tolerating temporal jitter ranging from 0 to 20 ms and to calculate their statistical significance, a modified method of the 'Unitary Events' analysis was used. Two main results were obtained. First, simultaneously recorded neurones synchronize their spiking activity in a highly dynamic way. Synchronization becomes significant only during short periods (about 100 to 200 ms). Several such periods occurred during a behavioural trial more or less regularly. Second, in many pairs of neurones, the temporal precision of synchronous activity was highest at the end of the preparatory period. As a matter of fact, at the beginning of this period, after the presentation of the preparatory signal, neurones significantly synchronize their spiking activity, but with low temporal precision. As time advances, significant synchronization becomes more precise. Data indicate that not only the discharge rate is involved in preparatory processes, but also temporal aspects of neuronal activity as expressed in the precise synchronization

  12. Bilateral tDCS on Primary Motor Cortex: Effects on Fast Arm Reaching Tasks

    PubMed Central

    Arias, Pablo; Corral-Bergantiños, Yoanna; Robles-García, Verónica; Madrid, Antonio; Oliviero, Antonio; Cudeiro, Javier

    2016-01-01

    Background The effects produced by transcranial direct current stimulation (tDCS) applied to the motor system have been widely studied in the past, chiefly focused on primary motor cortex (M1) excitability. However, the effects on functional tasks are less well documented. Objective This study aims to evaluate the effect of tDCS-M1 on goal-oriented actions (i.e., arm-reaching movements; ARM), in a reaction-time protocol. Methods 13 healthy subjects executed dominant ARM as fast as possible to one of two targets in front of them while surface EMG was recorded. Participants performed three different sessions. In each session they first executed ARM (Pre), then received tDCS, and finally executed Post, similar to Pre. Subjects received three different types of tDCS, one per session: In one session the anode was on right-M1 (AR), and the cathode on the left-M1 (CL), thus termed AR-CL; AL-CR reversed the montage; and Sham session was applied likewise. Real stimulation was 1mA-10min while subjects at rest. Three different variables and their coefficients of variation (CV) were analyzed: Premotor times (PMT), reaction-times (RT) and movement-times (MT). Results triceps-PMT were significantly increased at Post-Sham, suggesting fatigue. Results obtained with real tDCS were not different depending on the montage used, in both cases PMT were significantly reduced in all recorded muscles. RT and MT did not change for real or sham stimulation. RT-CV and PMT-CV were reduced after all stimulation protocols. Conclusion tDCS reduces premotor time and fatigability during the execution of fast motor tasks. Possible underlying mechanisms are discussed. PMID:27490752

  13. Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex.

    PubMed

    Lu, Yao; Truccolo, Wilson; Wagner, Fabien B; Vargas-Irwin, Carlos E; Ozden, Ilker; Zimmermann, Jonas B; May, Travis; Agha, Naubahar S; Wang, Jing; Nurmikko, Arto V

    2015-06-01

    Transient gamma-band (40-80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions.

  14. Local field potentials in primate motor cortex encode grasp kinetic parameters

    PubMed Central

    Milekovic, Tomislav; Truccolo, Wilson; Grün, Sonja; Riehle, Alexa; Brochier, Thomas

    2015-01-01

    Reach and grasp kinematics are known to be encoded in the spiking activity of neuronal ensembles and in local field potentials (LFPs) recorded from primate motor cortex during movement planning and execution. However, little is known, especially in LFPs, about the encoding of kinetic parameters, such as forces exerted on the object during the same actions. We implanted two monkeys with microelectrode arrays in the motor cortical areas MI and PMd to investigate encoding of grasp-related parameters in motor cortical LFPs during planning and execution of reach-and-grasp movements. We identified three components of the LFP that modulated during grasps corresponding to low (0.3 - 7Hz), intermediate (∼10 - ∼40Hz) and high (∼80 - 250Hz) frequency bands. We show that all three components can be used to classify not only grip types but also object loads during planning and execution of a grasping movement. In addition, we demonstrate that all three components recorded during planning or execution can be used to continuously decode finger pressure forces and hand position related to the grasping movement. Low and high frequency components provide similar classification and decoding accuracies, which were substantially higher than those obtained from the intermediate frequency component. Our results demonstrate that intended reach and grasp kinetic parameters are encoded in multiple LFP bands during both movement planning and execution. These findings also suggest that the LFP is a reliable signal for the control of parameters related to object load and applied pressure forces in brain-machine interfaces. PMID:25869861

  15. Stability of output effects from motor cortex to forelimb muscles in primates

    PubMed Central

    Griffin, D.M.; Hudson, H.M.; Belhaj-Saïf, A.; Cheney, P.D.

    2009-01-01

    Stimulus-triggered averaging (StTA) of electromyographic (EMG) activity is a form of intracortical microstimulation that enables documentation in awake animals of the sign, magnitude, latency and distribution of output effects from cortical and brainstem areas to motoneurons of different muscles. In this study, we show that the properties of effects in StTAs are stable and mostly independent of task conditions. StTAs of EMG activity from 24 forelimb muscles were collected from two male rhesus monkeys while they performed three tasks: 1) an isometric step tracking wrist task, 2) an isometric whole arm push-pull task and 3) a reach-to-grasp task. Layer V sites in primary motor cortex were identified and microstimuli were applied (15 μA) at a low rate (15 Hz). Our results show that the sign of effects (facilitation or suppression) in StTAs of EMG activity are remarkably stable in the presence of joint angle position changes (96% stable), whole arm posture changes (97% stable) and across fundamentally different types of tasks such as arm push-pull versus reach-to-grasp (81% stable). Further, comparing effects across different phases of a task also yielded remarkable stability (range: 84% - 96%). At different shoulder, elbow and wrist angles, the magnitudes of effects in individual muscles were highly correlated. Our results demonstrate that M1 output effects obtained with StTA of EMG activity are highly stable across widely varying joint angles and motor tasks. This study further validates the use of StTA for mapping and other studies of cortical motor output. PMID:19211898

  16. Early visuomotor integration processes induce LTP/LTD-like plasticity in the human motor cortex.

    PubMed

    Suppa, A; Li Voti, P; Rocchi, L; Papazachariadis, O; Berardelli, A

    2015-03-01

    To investigate whether visuomotor integration processes induce long-term potentiation (LTP) and depression (LTD)-like plasticity in the primary motor cortex (M1), we designed a new paired associative stimulation (PAS) protocol coupling left primary visual area (V1) activation achieved by hemifield visual evoked potentials (VEPs) and transcranial magnetic stimulation (TMS) over the left M1, at specific interstimulus intervals (ISIs), delivered at 1 Hz (V-PAS). Before and after V-PAS, we measured motor evoked potentials (MEPs). To clarify the mechanisms underlying V-PAS, we tested the effect of 1-Hz repetitive TMS (rTMS), 0.25-Hz V-PAS and rTMS, and a shorter 0.25-Hz V-PAS protocol. To examine V-PAS with contralateral V1 activation, we delivered V-PAS activating the right V1. To clarify whether V-PAS increases V1 activity or parieto- and premotor-to-M1 connectivity, before and after V-PAS, we examined VEPs and MEPs evoked by paired-pulse techniques. V-PAS increased, decreased, or left MEPs unchanged according to the ISI used. After 1-Hz rTMS MEPs decreased. Although 0.25-Hz rTMS elicited no aftereffect, 0.25-Hz V-PAS modulated MEPs according to the ISI used. The short 0.25-Hz V-PAS protocol left MEPs unchanged. Contralateral V-PAS inhibited MEPs. After V-PAS, VEPs remained unchanged and the premotor-to-M1 inhibitory connections decreased. V-PAS induces M1 LTP/LTD-like plasticity by activating premotor-to-motor connections.

  17. Electrical stimulation of motor cortex in the uninjured hemisphere after chronic unilateral injury promotes recovery of skilled locomotion through ipsilateral control.

    PubMed

    Carmel, Jason B; Kimura, Hiroki; Martin, John H

    2014-01-08

    Partial injury to the corticospinal tract (CST) causes sprouting of intact axons at their targets, and this sprouting correlates with functional improvement. Electrical stimulation of motor cortex augments sprouting of intact CST axons and promotes functional recovery when applied soon after injury. We hypothesized that electrical stimulation of motor cortex in the intact hemisphere after chronic lesion of the CST in the other hemisphere would restore function through ipsilateral control. To test motor skill, rats were trained and tested to walk on a horizontal ladder with irregularly spaced rungs. Eight weeks after injury, produced by pyramidal tract transection, half of the rats received forelimb motor cortex stimulation of the intact hemisphere. Rats with injury and stimulation had significantly improved forelimb control compared with rats with injury alone and achieved a level of proficiency similar to uninjured rats. To test whether recovery of forelimb function was attributable to ipsilateral control, we selectively inactivated the stimulated motor cortex using the GABA agonist muscimol. The dose of muscimol we used produces strong contralateral but no ipsilateral impairments in naive rats. In rats with injury and stimulation, but not those with injury alone, inactivation caused worsening of forelimb function; the initial deficit was reinstated. These results demonstrate that electrical stimulation can promote recovery of motor function when applied late after injury and that motor control can be exerted from the ipsilateral motor cortex. These results suggest that the uninjured motor cortex could be targeted for brain stimulation in people with large unilateral CST lesions.

  18. The relationship between soleus and gastrocnemius muscle activity in conscious cats--a model for motor unit recruitment?

    PubMed

    Hodgson, J A

    1983-04-01

    Force and electromyogram (e.m.g.) data were recorded from medial gastrocnemius and soleus muscles of conscious cats using chronically implanted devices. A digital computer was used to take simultaneous samples of the data from both muscles and construct two-dimensional frequency distributions relating the activities in the two muscles. The results show that posture is the only activity where soleus may be active without corresponding activity in the medial gastrocnemius muscle. In locomotion the ratio between soleus and medial gastrocnemius muscle activities changed with treadmill speed, although peak soleus force remained constant at approximately 80% of the isometric tetanic tension measured in terminal experiments. A hypothesis is put forward, associating these findings with the activities of slow and fast motor units and emphasizing the influence of neural activity in the determination of motor unit recruitment.

  19. Chronic ethanol exposure during adolescence in rats induces motor impairments and cerebral cortex damage associated with oxidative stress.

    PubMed

    Teixeira, Francisco Bruno; Santana, Luana Nazaré da Silva; Bezerra, Fernando Romualdo; De Carvalho, Sabrina; Fontes-Júnior, Enéas Andrade; Prediger, Rui Daniel; Crespo-López, Maria Elena; Maia, Cristiane Socorro Ferraz; Lima, Rafael Rodrigues

    2014-01-01

    Binge drinking is common among adolescents, and this type of ethanol exposure may lead to long-term nervous system damage. In the current study, we evaluated motor performance and tissue alterations in the cerebral cortex of rats subjected to intermittent intoxication with ethanol from adolescence to adulthood. Adolescent male Wistar rats (35 days old) were treated with distilled water or ethanol (6.5 g/kg/day, 22.5% w/v) during 55 days by gavage to complete 90 days of age. The open field, inclined plane and the rotarod tests were used to assess the spontaneous locomotor activity and motor coordination performance in adult animals. Following completion of behavioral tests, half of animals were submitted to immunohistochemical evaluation of NeuN (marker of neuronal bodies), GFAP (a marker of astrocytes) and Iba1 (microglia marker) in the cerebral cortex while the other half of the animals were subjected to analysis of oxidative stress markers by biochemical assays. Chronic ethanol intoxication in rats from adolescence to adulthood induced significant motor deficits including impaired spontaneous locomotion, coordination and muscle strength. These behavioral impairments were accompanied by marked changes in all cellular populations evaluated as well as increased levels of nitrite and lipid peroxidation in the cerebral cortex. These findings indicate that continuous ethanol intoxication from adolescence to adulthood is able to provide neurobehavioral and neurodegenerative damage to cerebral cortex.

  20. Primary Sensory and Motor Cortex Excitability Are Co-Modulated in Response to Peripheral Electrical Nerve Stimulation

    PubMed Central

    Schabrun, Siobhan M.; Ridding, Michael C.; Galea, Mary P.; Hodges, Paul W.; Chipchase, Lucinda S.

    2012-01-01

    Peripheral electrical stimulation (PES) is a common clinical technique known to induce changes in corticomotor excitability; PES applied to induce a tetanic motor contraction increases, and PES at sub-motor threshold (sensory) intensities decreases, corticomotor excitability. Understanding of the mechanisms underlying these opposite changes in corticomotor excitability remains elusive. Modulation of primary sensory cortex (S1) excitability could underlie altered corticomotor excitability with PES. Here we examined whether changes in primary sensory (S1) and motor (M1) cortex excitability follow the same time-course when PES is applied using identical stimulus parameters. Corticomotor excitability was measured using transcranial magnetic stimulation (TMS) and sensory cortex excitability using somatosensory evoked potentials (SEPs) before and after 30 min of PES to right abductor pollicis brevis (APB). Two PES paradigms were tested in separate sessions; PES sufficient to induce a tetanic motor contraction (30–50 Hz; strong motor intensity) and PES at sub motor-threshold intensity (100 Hz). PES applied to induce strong activation of APB increased the size of the N20-P25 component, thought to reflect sensory processing at cortical level, and increased corticomotor excitability. PES at sensory intensity decreased the size of the P25-N33 component and reduced corticomotor excitability. A positive correlation was observed between the changes in amplitude of the cortical SEP components and corticomotor excitability following sensory and motor PES. Sensory PES also increased the sub-cortical P14-N20 SEP component. These findings provide evidence that PES results in co-modulation of S1 and M1 excitability, possibly due to cortico-cortical projections between S1 and M1. This mechanism may underpin changes in corticomotor excitability in response to afferent input generated by PES. PMID:23227260

  1. Primary sensory and motor cortex excitability are co-modulated in response to peripheral electrical nerve stimulation.

    PubMed

    Schabrun, Siobhan M; Ridding, Michael C; Galea, Mary P; Hodges, Paul W; Chipchase, Lucinda S

    2012-01-01

    Peripheral electrical stimulation (PES) is a common clinical technique known to induce changes in corticomotor excitability; PES applied to induce a tetanic motor contraction increases, and PES at sub-motor threshold (sensory) intensities decreases, corticomotor excitability. Understanding of the mechanisms underlying these opposite changes in corticomotor excitability remains elusive. Modulation of primary sensory cortex (S1) excitability could underlie altered corticomotor excitability with PES. Here we examined whether changes in primary sensory (S1) and motor (M1) cortex excitability follow the same time-course when PES is applied using identical stimulus parameters. Corticomotor excitability was measured using transcranial magnetic stimulation (TMS) and sensory cortex excitability using somatosensory evoked potentials (SEPs) before and after 30 min of PES to right abductor pollicis brevis (APB). Two PES paradigms were tested in separate sessions; PES sufficient to induce a tetanic motor contraction (30-50 Hz; strong motor intensity) and PES at sub motor-threshold intensity (100 Hz). PES applied to induce strong activation of APB increased the size of the N(20)-P(25) component, thought to reflect sensory processing at cortical level, and increased corticomotor excitability. PES at sensory intensity decreased the size of the P25-N33 component and reduced corticomotor excitability. A positive correlation was observed between the changes in amplitude of the cortical SEP components and corticomotor excitability following sensory and motor PES. Sensory PES also increased the sub-cortical P(14)-N(20) SEP component. These findings provide evidence that PES results in co-modulation of S1 and M1 excitability, possibly due to cortico-cortical projections between S1 and M1. This mechanism may underpin changes in corticomotor excitability in response to afferent input generated by PES.

  2. Efficacy and interindividual variability in motor-cortex plasticity following anodal tDCS and paired-associative stimulation.

    PubMed

    Strube, Wolfgang; Bunse, Tilmann; Malchow, Berend; Hasan, Alkomiet

    2015-01-01

    Interindividual response variability to various motor-cortex stimulation protocols has been recently reported. Comparative data of stimulation protocols with different modes of action is lacking. We aimed to compare the efficacy and response variability of two LTP-inducing stimulation protocols in the human motor cortex: anodal transcranial direct current stimulation (a-tDCS) and paired-associative stimulation (PAS25). In two experiments 30 subjects received 1mA a-tDCS and PAS25. Data analysis focused on motor-cortex excitability change and response defined as increase in MEP applying different cut-offs. Furthermore, the predictive pattern of baseline characteristics was explored. Both protocols induced a significant increase in motor-cortical excitability. In the PAS25 experiments the likelihood to develop a MEP response was higher compared to a-tDCS, whereas for intracortical facilitation (ICF) the likelihood for a response was higher in the a-tDCS experiments. Baseline ICF (12 ms) correlated positively with an increase in MEPs only following a-tDCS and responders had significantly higher ICF baseline values. Contrary to recent studies, we showed significant group-level efficacy following both stimulation protocols confirming older studies. However, we also observed a remarkable amount of nonresponders. Our findings highlight the need to define sufficient physiological read-outs for a given plasticity protocol and to develop predictive markers for targeted stimulation.

  3. Remapping in the ipsilesional motor cortex after VR-based training: a pilot fMRI study.

    PubMed

    Tunik, Eugene; Adamovich, Sergei V

    2009-01-01

    In a single case longitudinal study, a 70 year old female subject who has had a subcortical stroke 8 years prior, was tested three times in fMRI using an interactive MRI-compatible VR environment. The subject performed sequential finger movements with her right (unaffected) hand. Her hand motion (recorded with the data glove) animated either the ipsilateral (corresponding) or contralateral (mirrored) virtual hand model. In a visual feedback control condition, the virtual hand models were replaced with ellipsoids. In between the second and third session, the patient participated in an intensive, two-week long VR-based training of her affected upper extremity. When comparing activation in the mirrored versus the non-mirrored virtual visual feedback condition, no significant activation was noted in motor or premotor areas in the baseline 1 or baseline 2 sessions. However, increased activation in the ipsilesional motor cortex occurred as a result of training, despite the absence of active involvement of the ipsilesional motor cortex in this condition. The left motor cortex was also recruited in this condition (though weaker) despite the subtracted out ellipsoid condition (in which subjects also moved their hand). Thus, the contralateral (mirrored) visual feedback may have had a facilitory effect bilaterally. These findings might have some important implications for the development of novel therapies in the acute phase, when paresis and the potential for neural remapping are greatest.

  4. Intracisternal delivery of AAV9 results in oligodendrocyte and motor neuron transduction in the whole central nervous system of cats.

    PubMed

    Bucher, T; Dubreil, L; Colle, M-A; Maquigneau, M; Deniaud, J; Ledevin, M; Moullier, P; Joussemet, B

    2014-05-01

    Systemic and intracerebrospinal fluid delivery of adeno-associated virus serotype 9 (AAV9) has been shown to achieve widespread gene delivery to the central nervous system (CNS). However, after systemic injection, the neurotropism of the vector has been reported to vary according to age at injection, with greater neuronal transduction in newborns and preferential glial cell tropism in adults. This difference has not yet been reported after cerebrospinal fluid (CSF) delivery. The present study analyzed both neuronal and glial cell transduction in the CNS of cats according to age of AAV9 CSF injection. In both newborns and young cats, administration of AAV9-GFP in the cisterna magna resulted in high levels of motor neurons (MNs) transduction from the cervical (84±5%) to the lumbar (99±1%) spinal cord, demonstrating that the remarkable tropism of AAV9 for MNs is not affected by age at CSF delivery. Surprisingly, numerous oligodendrocytes were also transduced in the brain and in the spinal cord white matter of young cats, but not of neonates, indicating that (i) age of CSF delivery influences the tropism of AAV9 for glial cells and (ii) AAV9 intracisternal delivery could be relevant for both the treatment of MN and demyelinating disorders.

  5. [Conditioned reflex changes in the intra-analyzer interaction of the afferent inputs from the lateral geniculate body and pulvinar thalami in the cerebral cortex of cats].

    PubMed

    Shumikhina, S I

    1986-01-01

    Paired heterogeneous stimulation of the lateral geniculate body (LGB) and pulvinar (Pulv) as a conditioned stimulus of alimentary instrumental conditioned reflex (CR), resulted in a change of relations between afferent inputs from LGB and Pulv to the visual and associative cortex of cats. At stimulation of LGB preceding by 40 ms, facilitation of the response to testing Pulv stimulation observed in untrained cats, appeared only at the beginning of the learning and was suppressed by the end of elaboration, when the amplitude of the response to the conditioning LGB stimulation greatly increased. In the process of CR elaboration (in the middle of learning), Pulv stimulation preceding by 40 ms facilitated the response to the testing LGB stimulation and simultaneously increased the amplitude of the response to the conditioning Pulv stimulation.

  6. Sensory-motor interactions for vocal pitch monitoring in non-primary human auditory cortex.

    PubMed

    Greenlee, Jeremy D W; Behroozmand, Roozbeh; Larson, Charles R; Jackson, Adam W; Chen, Fangxiang; Hansen, Daniel R; Oya, Hiroyuki; Kawasaki, Hiroto; Howard, Matthew A

    2013-01-01

    The neural mechanisms underlying processing of auditory feedback during self-vocalization are poorly understood. One technique used to study the role of auditory feedback involves shifting the pitch of the feedback that a speaker receives, known as pitch-shifted feedback. We utilized a pitch shift self-vocalization and playback paradigm to investigate the underlying neural mechanisms of audio-vocal interaction. High-resolution electrocorticography (ECoG) signals were recorded directly from auditory cortex of 10 human subjects while they vocalized and received brief downward (-100 cents) pitch perturbations in their voice auditory feedback (speaking task). ECoG was also recorded when subjects passively listened to playback of their own pitch-shifted vocalizations. Feedback pitch perturbations elicited average evoked potential (AEP) and event-related band power (ERBP) responses, primarily in the high gamma (70-150 Hz) range, in focal areas of non-primary auditory cortex on superior temporal gyrus (STG). The AEPs and high gamma responses were both modulated by speaking compared with playback in a subset of STG contacts. From these contacts, a majority showed significant enhancement of high gamma power and AEP responses during speaking while the remaining contacts showed attenuated response amplitudes. The speaking-induced enhancement effect suggests that engaging the vocal motor system can modulate auditory cortical processing of self-produced sounds in such a way as to increase neural sensitivity for feedback pitch error detection. It is likely that mechanisms such as efference copies may be involved in this process, and modulation of AEP and high gamma responses imply that such modulatory effects may affect different cortical generators within distinctive functional networks that drive voice production and control.

  7. Functional coupling between motor and sensory nerves through contraction of sphincters in the pudendal area of the female cat.

    PubMed

    Lagunes-Córdoba, Roberto; Hernández, Pablo Rogelio; Raya, José Guadalupe; Muñoz-Martínez, E J

    2010-01-01

    The question of whether skin receptors might help in the perception of muscle contraction and body movement has not been settled. The present study gives direct evidence of skin receptor firing in close coincidence with the contraction of the vaginal and anal sphincters. The distal stump of the sectioned motor pudendal nerve was stimulated. Single shocks induced a wavelike increase in the lumen pressure of the distal vagina and the anal canal, as well as constriction of the vaginal introitus and the anus. The constriction pulls on and moves the surrounding skin, which was initially detected visually. In the present experiments, a thin strain gauge that pressed on the skin surface detected its displacement. Single shocks to the motor nerve induced a wave of skin movement with maximal amplitude at 5 mm from the anus and propagated with decrement beyond 35 mm. The peripheral terminals of the sensory pudendal nerve and the posterior femoral nerve supply the skin that moves. Sensory axons from both nerves fired in response to both tactile stimulation and the skin movement produced by the constriction of the orifices (motor-sensory coupling). In cats with all nerves intact, a single shock to the sensory nerves induced reflex waves of skin movement and lumen pressure (sensory-motor coupling). Both couplings provide evidence for a feedforward action that might help to maintain the female posture during mating and to the perception of muscle contraction.

  8. The release of acetylcholine from the spinal cord of the cat by antidromic stimulation of motor nerves

    PubMed Central

    Kuno, M.; Rudomin, P.

    1966-01-01

    1. ACh was measured in the effluent from the perfused lumbosacral cord of the cat with or without stimulation of the central ends of the cut left sciatic and femoral nerves after section of the left dorsal roots. 2. In about 30% of the preparations ACh was obtained in the samples collected at rest (average 3·3 ng/min); the amount of ACh release was increased 1·3-9 times by stimulation of the peripheral nerves. The average amount of ACh collected during stimulation of the peripheral nerves at 5/sec was 6·9 ng/min. Antidromic motor nerve impulses responsible for the ACh release were likely to be only those in alpha motor fibres. 3. There was a depression in ACh release/stimulus as the stimulus frequency was increased more than 10/sec. Such changes in ACh release with various stimulus frequencies were correlated with depression in the response of Renshaw cells to excitation through motor-axon collaterals. 4. Amounts of ACh release during stimulation of the peripheral nerves at 5/sec were significantly increased for 1 or 2 min after a short tetanic stimulation of the nerves. 5. Intravenous injection of dihydro-β-erythroidine did not reduce the amount of ACh release produced by stimulation of the peripheral nerves. 6. It is concluded that antidromic impulses in alpha motor fibres liberate ACh from the presynaptic terminals at the central synapses on Renshaw cells. PMID:5972160

  9. The release of acetylcholine from the spinal cord of the cat by antidromic stimulation of motor nerves.

    PubMed

    Kuno, M; Rudomin, P

    1966-11-01

    1. ACh was measured in the effluent from the perfused lumbosacral cord of the cat with or without stimulation of the central ends of the cut left sciatic and femoral nerves after section of the left dorsal roots.2. In about 30% of the preparations ACh was obtained in the samples collected at rest (average 3.3 ng/min); the amount of ACh release was increased 1.3-9 times by stimulation of the peripheral nerves. The average amount of ACh collected during stimulation of the peripheral nerves at 5/sec was 6.9 ng/min. Antidromic motor nerve impulses responsible for the ACh release were likely to be only those in alpha motor fibres.3. There was a depression in ACh release/stimulus as the stimulus frequency was increased more than 10/sec. Such changes in ACh release with various stimulus frequencies were correlated with depression in the response of Renshaw cells to excitation through motor-axon collaterals.4. Amounts of ACh release during stimulation of the peripheral nerves at 5/sec were significantly increased for 1 or 2 min after a short tetanic stimulation of the nerves.5. Intravenous injection of dihydro-beta-erythroidine did not reduce the amount of ACh release produced by stimulation of the peripheral nerves.6. It is concluded that antidromic impulses in alpha motor fibres liberate ACh from the presynaptic terminals at the central synapses on Renshaw cells.

  10. Temporal discharge patterns evoked by rapid sequences of wide- and narrowband clicks in the primary auditory cortex of cat.

    PubMed

    Lu, T; Wang, X

    2000-07-01

    The present study investigated neural responses to rapid, repetitive stimuli in the primary auditory cortex (A1) of cats. We focused on two important issues regarding cortical coding of sequences of stimuli: temporal discharge patterns of A1 neurons as a function of inter-stimulus interval and cortical mechanisms for representing successive stimulus events separated by very short intervals. These issues were studied using wide- and narrowband click trains with inter-click intervals (ICIs) ranging from 3 to 100 ms as a class of representative sequential stimuli. The main findings of this study are 1) A1 units displayed, in response to click train stimuli, three distinct temporal discharge patterns that we classify as regions I, II, and III. At long ICIs nearly all A1 units exhibited typical stimulus-synchronized response patterns (region I) consistent with previously reported observations. At intermediate ICIs, no clear temporal structures were visible in the responses of most A1 units (region II). At short ICIs, temporal discharge patterns are characterized by the presence of either intrinsic oscillations (at approximately 10 Hz) or a change in discharge rate that was a monotonically decreasing function of ICI (region III). In some A1 units, temporal discharge patterns corresponding to region III were absent. 2) The boundary between regions I and II (synchronization boundary) had a median value of 39.8 ms ICI ([25%, 75%] = [20.4, 58. 8] ms ICI; n = 131). The median boundary between regions II and III was estimated at 6.3 ms ([25%, 75%] = [5.2, 9.7] ms ICI; n = 47) for units showing rate changes (rate-change boundary). 3) The boundary values between different regions appeared to be relatively independent of stimulus intensity (at modest sound levels) or the bandwidth of the clicks used.