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1.
Nature ; 579(7798): 256-259, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32132709

RESUMO

Most cortical synapses are local and excitatory. Local recurrent circuits could implement amplification, allowing pattern completion and other computations1-4. Cortical circuits contain subnetworks that consist of neurons with similar receptive fields and increased connectivity relative to the network average5,6. Cortical neurons that encode different types of information are spatially intermingled and distributed over large brain volumes5-7, and this complexity has hindered attempts to probe the function of these subnetworks by perturbing them individually8. Here we use computational modelling, optical recordings and manipulations to probe the function of recurrent coupling in layer 2/3 of the mouse vibrissal somatosensory cortex during active tactile discrimination. A neural circuit model of layer 2/3 revealed that recurrent excitation enhances sensory signals by amplification, but only for subnetworks with increased connectivity. Model networks with high amplification were sensitive to damage: loss of a few members of the subnetwork degraded stimulus encoding. We tested this prediction by mapping neuronal selectivity7 and photoablating9,10 neurons with specific selectivity. Ablation of a small proportion of layer 2/3 neurons (10-20, less than 5% of the total) representing touch markedly reduced responses in the spared touch representation, but not in other representations. Ablations most strongly affected neurons with stimulus responses that were similar to those of the ablated population, which is also consistent with network models. Recurrence among cortical neurons with similar selectivity therefore drives input-specific amplification during behaviour.


Assuntos
Modelos Neurológicos , Neurônios/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Simulação por Computador , Camundongos , Tato/fisiologia
2.
Neuron ; 105(1): 16-33, 2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31917952

RESUMO

Many brain areas modulate their activity during vibrotactile tasks. The activity from these areas may code the stimulus parameters, stimulus perception, or perceptual reports. Here, we discuss findings obtained in behaving monkeys aimed to understand these processes. In brief, neurons from the somatosensory thalamus and primary somatosensory cortex (S1) only code the stimulus parameters during the stimulation periods. In contrast, areas downstream of S1 code the stimulus parameters during not only the task components but also perception. Surprisingly, the midbrain dopamine system is an actor not considered before in perception. We discuss the evidence that it codes the subjective magnitude of a sensory percept. The findings reviewed here may help us to understand where and how sensation transforms into perception in the brain.


Assuntos
Neurônios Dopaminérgicos/fisiologia , Mesencéfalo/fisiologia , Córtex Somatossensorial/fisiologia , Tálamo/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Animais
3.
Nat Neurosci ; 22(11): 1771-1781, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31636449

RESUMO

Microglia dynamically survey the brain parenchyma. Microglial processes interact with neuronal elements; however, what role neuronal network activity plays in regulating microglial dynamics is not entirely clear. Most studies of microglial dynamics use either slice preparations or in vivo imaging in anesthetized mice. Here we demonstrate that microglia in awake mice have a relatively reduced process area and surveillance territory and that reduced neuronal activity under general anesthesia increases microglial process velocity, extension and territory surveillance. Similarly, reductions in local neuronal activity through sensory deprivation or optogenetic inhibition increase microglial process surveillance. Using pharmacological and chemogenetic approaches, we demonstrate that reduced norepinephrine signaling is necessary for these increases in microglial process surveillance. These findings indicate that under basal physiological conditions, noradrenergic tone in awake mice suppresses microglial process surveillance. Our results emphasize the importance of awake imaging for studying microglia-neuron interactions and demonstrate how neuronal activity influences microglial process dynamics.


Assuntos
Microglia/fisiologia , Neurônios/fisiologia , Norepinefrina/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Encéfalo/efeitos dos fármacos , Receptor 1 de Quimiocina CX3C/genética , Clozapina/análogos & derivados , Clozapina/farmacologia , Isoflurano/farmacologia , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Microglia/efeitos dos fármacos , Microinjeções , Muscimol/farmacologia , Norepinefrina/farmacologia , Optogenética , Propanolaminas/farmacologia , Propranolol/farmacologia , Receptores Purinérgicos P2Y12/genética , Privação Sensorial/fisiologia , Córtex Somatossensorial/efeitos dos fármacos , Tetrodotoxina/farmacologia , Vigília
4.
Nat Commun ; 10(1): 4549, 2019 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-31591398

RESUMO

Interhemispheric axons of the corpus callosum (CC) facilitate the higher order functions of the cerebral cortex. According to current views, callosal and non-callosal fates are determined early after a neuron's birth, and certain populations, such as cortical layer (L) 4 excitatory neurons of the primary somatosensory (S1) barrel, project only ipsilaterally. Using a novel axonal-retrotracing strategy and GFP-targeted visualization of Rorb+ neurons, we instead demonstrate that L4 neurons develop transient interhemispheric axons. Locally restricted L4 connectivity emerges when exuberant contralateral axons are refined in an area- and layer-specific manner during postnatal development. Surgical and genetic interventions of sensory circuits demonstrate that refinement rates depend on distinct inputs from sensory-specific thalamic nuclei. Reductions in input-dependent refinement result in mature functional interhemispheric hyperconnectivity, demonstrating the plasticity and bona fide callosal potential of L4 neurons. Thus, L4 neurons discard alternative interhemispheric circuits as instructed by thalamic input. This may ensure optimal wiring.


Assuntos
Axônios/fisiologia , Corpo Caloso/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Animais Recém-Nascidos , Axônios/metabolismo , Corpo Caloso/citologia , Corpo Caloso/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Microscopia Confocal , Neurônios/metabolismo , Células Receptoras Sensoriais/metabolismo , Células Receptoras Sensoriais/fisiologia , Córtex Somatossensorial/citologia , Córtex Somatossensorial/metabolismo , Tálamo/citologia , Tálamo/metabolismo , Tálamo/fisiologia
5.
Nat Commun ; 10(1): 4634, 2019 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-31604919

RESUMO

Touch is a fundamental aspect of social, parental and sexual behavior. In contrast to our detailed knowledge about cortical processing of non-social touch, we still know little about how social touch impacts cortical circuits. We investigated neural activity across five frontal, motor and sensory cortical areas in rats engaging in naturalistic social facial touch. Information about social touch and the sex of the interaction partner (a biologically significant feature) is a major determinant of cortical activity. 25.3% of units were modulated during social touch and 8.3% of units displayed 'sex-touch' responses (responded differently, depending on the sex of the interaction partner). Single-unit responses were part of a structured, partner-sex- and, in some cases, subject-sex-dependent population response. Spiking neural network simulations indicate that a change in inhibitory drive might underlie these population dynamics. Our observations suggest that socio-sexual characteristics of touch (subject and partner sex) widely modulate cortical activity and need to be investigated with cellular resolution.


Assuntos
Comportamento Social , Córtex Somatossensorial/fisiologia , Tato/fisiologia , Vibrissas/fisiologia , Animais , Comportamento Animal , Feminino , Masculino , Rede Nervosa , Dinâmica Populacional , Ratos , Análise de Regressão , Fatores Sexuais
6.
PLoS Biol ; 17(10): e3000469, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31613874

RESUMO

Newly learned motor skills are initially labile and then consolidated to permit retention. The circuits that enable the consolidation of motor memories remain uncertain. Most work to date has focused on primary motor cortex, and although there is ample evidence of learning-related plasticity in motor cortex, direct evidence for its involvement in memory consolidation is limited. Learning-related plasticity is also observed in somatosensory cortex, and accordingly, it may also be involved in memory consolidation. Here, by using transcranial magnetic stimulation (TMS) to block consolidation, we report the first direct evidence that plasticity in somatosensory cortex participates in the consolidation of motor memory. Participants made movements to targets while a robot applied forces to the hand to alter somatosensory feedback. Immediately following adaptation, continuous theta-burst transcranial magnetic stimulation (cTBS) was delivered to block retention; then, following a 24-hour delay, which would normally permit consolidation, we assessed whether there was an impairment. It was found that when mechanical loads were introduced gradually to engage implicit learning processes, suppression of somatosensory cortex following training almost entirely eliminated retention. In contrast, cTBS to motor cortex following learning had little effect on retention at all; retention following cTBS to motor cortex was not different than following sham TMS stimulation. We confirmed that cTBS to somatosensory cortex interfered with normal sensory function and that it blocked motor memory consolidation and not the ability to retrieve a consolidated motor memory. In conclusion, the findings are consistent with the hypothesis that in adaptation learning, somatosensory cortex rather than motor cortex is involved in the consolidation of motor memory.


Assuntos
Potencial Evocado Motor/fisiologia , Retroalimentação Sensorial/fisiologia , Consolidação da Memória/fisiologia , Memória de Longo Prazo/fisiologia , Córtex Somatossensorial/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Córtex Motor/anatomia & histologia , Córtex Motor/fisiologia , Destreza Motora/fisiologia , Plasticidade Neuronal/fisiologia , Córtex Somatossensorial/anatomia & histologia , Estimulação Magnética Transcraniana
7.
Nat Commun ; 10(1): 4699, 2019 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-31619680

RESUMO

Regaining the function of an impaired limb is highly desirable in paralyzed individuals. One possible avenue to achieve this goal is to bridge the interrupted pathway between preserved neural structures and muscles using a brain-computer interface. Here, we demonstrate that monkeys with subcortical stroke were able to learn to use an artificial cortico-muscular connection (ACMC), which transforms cortical activity into electrical stimulation to the hand muscles, to regain volitional control of a paralysed hand. The ACMC induced an adaptive change of cortical activities throughout an extensive cortical area. In a targeted manner, modulating high-gamma activity became localized around an arbitrarily-selected cortical site controlling stimulation to the muscles. This adaptive change could be reset and localized rapidly to a new cortical site. Thus, the ACMC imparts new function for muscle control to connected cortical sites and triggers cortical adaptation to regain impaired motor function after stroke.


Assuntos
Adaptação Fisiológica/fisiologia , Interfaces Cérebro-Computador , Estimulação Elétrica , Córtex Motor/fisiopatologia , Músculo Esquelético/fisiologia , Córtex Somatossensorial/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Animais , Braço , Córtex Cerebral/fisiologia , Córtex Cerebral/fisiopatologia , Eletrocorticografia , Mãos , Macaca mulatta , Córtex Motor/fisiologia , Vias Neurais/fisiopatologia , Paralisia , Córtex Somatossensorial/fisiologia , Reabilitação do Acidente Vascular Cerebral , Punho
8.
Elife ; 82019 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-31418693

RESUMO

Sensory maps in layer (L) 2/3 of rodent cortex lack precise functional column boundaries, and instead exhibit locally heterogeneous (salt-and-pepper) tuning superimposed on smooth global topography. Could this organization be a byproduct of impoverished experience in laboratory housing? We compared whisker map somatotopy in L2/3 and L4 excitatory cells of somatosensory (S1) cortex in normally housed vs. tactile-enriched mice, using GCaMP6s imaging. Normally housed mice had a dispersed, salt-and-pepper whisker map in L2/3, but L4 was more topographically precise. Enrichment (P21 to P46-71) sharpened whisker tuning and decreased, but did not abolish, local tuning heterogeneity. In L2/3, enrichment strengthened and sharpened whisker point representations, and created functional boundaries of tuning similarity and noise correlations at column edges. Thus, enrichment drives emergence of functional columnar topography in S1, and reduces local tuning heterogeneity. These changes predict better touch detection by neural populations within each column.


Assuntos
Mapeamento Encefálico , Córtex Somatossensorial/anatomia & histologia , Córtex Somatossensorial/fisiologia , Percepção do Tato , Vibrissas/fisiologia , Animais , Proteínas de Fluorescência Verde/análise , Camundongos , Coloração e Rotulagem/métodos
9.
Exp Brain Res ; 237(10): 2747-2759, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31435693

RESUMO

Patients with lesions of the prefrontal cortex (PFC) show increased distractibility and impairments in inhibiting cortical responses to irrelevant stimuli. This study was designed to test the role of the PFC in the early modality-specific modulation of event-related potentials (ERPs) generated during a sensory selection task. The task required participants to make a scaled motor response to the amplitudes of visual and tactile stimuli presented individually or concurrently. Task relevance was manipulated and continuous theta burst stimulation (cTBS) was used to transiently inhibit PFC activity to test the contribution of the PFC to modulation of sensory gating. Electroencephalography (EEG) was collected from participants both before and after cTBS was applied. The somatosensory-evoked N70 ERP was shown to be modulated by task relevance before but not after cTBS was applied to the PFC, and downregulating PFC activity through the use of cTBS abolished any relevancy differences in N70 amplitude. In conclusion, this study demonstrated that early modality-specific changes in cortical somatosensory processing are modulated by attention, and that this effect is subserved by prefrontal cortical activity.


Assuntos
Atenção/fisiologia , Potenciais Somatossensoriais Evocados/fisiologia , Córtex Pré-Frontal/fisiologia , Tato/fisiologia , Adulto , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Filtro Sensorial/fisiologia , Córtex Somatossensorial/fisiologia , Adulto Jovem
10.
PLoS Biol ; 17(8): e3000431, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31454360

RESUMO

Motion is an essential component of everyday tactile experience: most manual interactions involve relative movement between the skin and objects. Much of the research on the neural basis of tactile motion perception has focused on how direction is encoded, but less is known about how speed is. Perceived speed has been shown to be dependent on surface texture, but previous studies used only coarse textures, which span a restricted range of tangible spatial scales and provide a limited window into tactile coding. To fill this gap, we measured the ability of human observers to report the speed of natural textures-which span the range of tactile experience and engage all the known mechanisms of texture coding-scanned across the skin. In parallel experiments, we recorded the responses of single units in the nerve and in the somatosensory cortex of primates to the same textures scanned at different speeds. We found that the perception of speed is heavily influenced by texture: some textures are systematically perceived as moving faster than are others, and some textures provide a more informative signal about speed than do others. Similarly, the responses of neurons in the nerve and in cortex are strongly dependent on texture. In the nerve, although all fibers exhibit speed-dependent responses, the responses of Pacinian corpuscle-associated (PC) fibers are most strongly modulated by speed and can best account for human judgments. In cortex, approximately half of the neurons exhibit speed-dependent responses, and this subpopulation receives strong input from PC fibers. However, speed judgments seem to reflect an integration of speed-dependent and speed-independent responses such that the latter help to partially compensate for the strong texture dependence of the former.


Assuntos
Percepção de Movimento/fisiologia , Percepção do Tato/fisiologia , Tato/fisiologia , Adulto , Animais , Feminino , Humanos , Macaca mulatta , Masculino , Movimento , Neurônios/fisiologia , Pele , Córtex Somatossensorial/fisiologia , Adulto Jovem
11.
Handb Clin Neurol ; 160: 313-327, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31277857

RESUMO

Brain mapping is often critical to the success of epilepsy and brain tumor surgeries. Mapping the cerebral cortex can be performed either extraoperatively or intraoperatively. When considering the optimal venue for a particular patient, a number of important considerations need to be considered including: the intended goals for the mapping, patient factors, anesthetic effects, stimulation parameters, cortical functions of interest, as well as the mapping modalities being considered. In this chapter, we will cover electrocorticography, cortical somatosensory evoked potentials, and the various neurophysiologic techniques used to map sensorimotor and cognitive functions, including language. One of the main uses of electrocorticography in epilepsy surgery is to map the cortical regions associated with epileptiform activity. This information is used to plan resection boundaries. Electrocorticography can also be used to monitor for afterdischarges (ADs) during direct cortical stimulation as well as for mapping high-frequency activity during various cognitive tasks. Cortical somatosensory evoked potentials can identify the central sulcus by mapping the dipolar activation of the primary somatosensory cortex that results from stimulation of the large fiber somatosensory pathway by peripheral nerve stimulation. Motor, sensory, and language cortex can also be identified by direct electrical cortical stimulation.


Assuntos
Mapeamento Encefálico/métodos , Eletrocorticografia/métodos , Monitorização Intraoperatória/métodos , Córtex Somatossensorial/fisiologia , Eletroencefalografia/métodos , Humanos , Monitorização Intraoperatória/instrumentação
12.
Brain Topogr ; 32(5): 783-793, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31218521

RESUMO

Paired-pulse suppression refers to attenuation of neural activity in response to a second stimulus and has a pivotal role in inhibition of redundant sensory inputs. Previous studies have suggested that cortical responses to a somatosensory stimulus are modulated not only by a preceding same stimulus, but also by stimulus from a different submodality. Using magnetoencephalography, we examined somatosensory suppression induced by three different conditioning stimuli. The test stimulus was a train of electrical pulses to the dorsum of the left hand at 100 Hz lasting 1500 ms. For the pulse train, the intensity of the stimulus was abruptly increased at 1200 ms. Cortical responses to the abrupt intensity change were recorded and used as the test response. Conditioning stimuli were presented at 600 ms as pure tones, either innocuous or noxious electrical stimulation to the right foot. Four stimulus conditions were used: (1) Test alone, (2) Test + auditory stimulus, (3) Test + somatosensory stimulus, and (4) Test + nociceptive stimulus. Our results showed that the amplitude of the test response was significantly smaller for conditions (3) and (4) in the secondary somatosensory cortex contralateral (cSII) and ipsilateral (iSII) to the stimulated side as compared to the response to condition (1), whereas the amplitude of the response in the primary somatosensory cortex did not differ among the conditions. The auditory stimulus did not have effects on somatosensory change-related response. These findings show that somatosensory suppression was induced by not only a conditioning stimulus of the same somatosensory submodality and the same cutaneous site to the test stimulus, but also by that of a different submodality in a remote area.


Assuntos
Estimulação Elétrica , Potenciais Somatossensoriais Evocados/fisiologia , Córtex Somatossensorial/fisiologia , Adulto , Feminino , Mãos , Humanos , Magnetoencefalografia , Masculino
13.
Biol Psychol ; 146: 107719, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31207259

RESUMO

Observing others being touched activates similar brain areas as those activated when one experiences a touch oneself. Event-related potential (ERP) studies have revealed that modulation of somatosensory components by observed touch occurs within 100 ms after stimulus onset, and such vicarious effects have been taken as evidence for empathy for others' tactile experiences. In previous studies body parts have been presented from a first person perspective. This raises the question of the extent to which somatosensory activation by observed touch to body parts depends on the perspective from which the body part is observed. In this study (N = 18), we examined the modulation of somatosensory ERPs by observed touch delivered to another person's hand when viewed as if from a first person versus a third person perspective. We found that vicarious touch effects primarily consist of two separable components in the early stages of somatosensory processing: an anatomical mapping for touch in first person perspective at P45, and a specular (mirror like) mapping for touch in third person perspective at P100. This is consistent with suggestions that vicarious representations exist to support predictions for one's own bodily events, but also to enable predictions of a social or interpersonal kind, at distinct temporal stages.


Assuntos
Relações Interpessoais , Córtex Somatossensorial/fisiologia , Tato/fisiologia , Adulto , Mapeamento Encefálico , Eletroencefalografia , Empatia , Potenciais Somatossensoriais Evocados/fisiologia , Feminino , Lateralidade Funcional/fisiologia , Mãos , Humanos , Masculino , Observação , Percepção do Tato , Adulto Jovem
14.
J Sports Sci Med ; 18(2): 327-336, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31191103

RESUMO

The purpose of this study was to examine the acute effects of short-term Achilles tendon vibration on plantar flexor torque, twitch contractile properties as well as muscle and cortical activity in young athletes. Eleven female elite soccer players aged 15.6 ± 0.5 years participated in this study. Three different conditions were applied in randomized order: Achilles tendon vibration (80 Hz) for 30 and 300 s, and a passive control condition (300 s). Tests at baseline and following conditions included the assessment of peak plantar flexor torque during maximum voluntary contraction, electrically evoked muscle twitches (e.g., potentiated twitch peak torque [PT]), and electromyographic (EMG) activity of the plantar flexors. Additionally, electroencephalographic (EEG) activity of the primary motor and somatosensory cortex were assessed during a submaximal dynamic concentric-eccentric plantar flexion exercise using an elastic rubber band. Large-sized main effects of condition were found for EEG absolute alpha-1 and beta-1 band power (p ≤ 0.011; 1.5 ≤ d ≤2.6). Post-hoc tests indicated that alpha-1 power was significantly lower at 30 and 300 s (p = 0.009; d = 0.8) and beta-1 power significantly lower at 300 s (p < 0.001; d = 0.2) compared to control condition. No significant effect of condition was found for peak plantar flexor torque, electrical evoked muscle twitches, and EMG activity. In conclusion, short-term local Achilles tendon vibration induced lower brain activity (i.e., alpha-1 and beta-1 band power) but did not affect lower limb peak torque, twitch contractile properties, and muscle activity. Lower brain activity following short-term local Achilles tendon vibration may indicate improved cortical function during a submaximal dynamic exercise in female young soccer players.


Assuntos
Tendão do Calcâneo/fisiologia , Córtex Motor/fisiologia , Contração Muscular , Músculo Esquelético/fisiologia , Córtex Somatossensorial/fisiologia , Torque , Vibração , Adolescente , Atletas , Estudos Cross-Over , Eletroencefalografia , Eletromiografia , Feminino , Humanos , Dinamômetro de Força Muscular , Futebol
15.
Nat Commun ; 10(1): 2585, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-31197148

RESUMO

During navigation, rodents continually sample the environment with their whiskers. How locomotion modulates neuronal activity in somatosensory cortex, and how it is integrated with whisker-touch remains unclear. Here, we compared neuronal activity in layer 2/3 (L2/3) and L5 of barrel cortex using calcium imaging in mice running in a tactile virtual reality. Both layers increase their activity during running and concomitant whisking, in the absence of touch. Fewer neurons are modulated by whisking alone. Whereas L5 neurons respond transiently to wall-touch during running, L2/3 neurons show sustained activity. Consistently, neurons encoding running-with-touch are more abundant in L2/3 and they encode the run-speed better during touch. Few neurons across layers were also sensitive to abrupt perturbations of tactile flow during running. In summary, locomotion significantly enhances barrel cortex activity across layers with L5 neurons mainly reporting changes in touch conditions and L2/3 neurons continually integrating tactile stimuli with running.


Assuntos
Locomoção/fisiologia , Neurônios/fisiologia , Córtex Somatossensorial/fisiologia , Tato/fisiologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Estimulação Física , Córtex Somatossensorial/citologia , Vibrissas/fisiologia
16.
PLoS Comput Biol ; 15(5): e1006716, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31150385

RESUMO

Cortical responses to sensory inputs vary across repeated presentations of identical stimuli, but how this trial-to-trial variability impacts detection of sensory inputs is not fully understood. Using multi-channel local field potential (LFP) recordings in primary somatosensory cortex (S1) of the awake mouse, we optimized a data-driven cortical state classifier to predict single-trial sensory-evoked responses, based on features of the spontaneous, ongoing LFP recorded across cortical layers. Our findings show that, by utilizing an ongoing prediction of the sensory response generated by this state classifier, an ideal observer improves overall detection accuracy and generates robust detection of sensory inputs across various states of ongoing cortical activity in the awake brain, which could have implications for variability in the performance of detection tasks across brain states.


Assuntos
Biologia Computacional/métodos , Córtex Somatossensorial/fisiologia , Vigília/fisiologia , Animais , Encéfalo/fisiologia , Confiabilidade dos Dados , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Reprodutibilidade dos Testes
17.
Neuron ; 103(2): 277-291.e4, 2019 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-31151774

RESUMO

Neocortical circuits are sensitive to experience, showing both anatomical and electrophysiological changes in response to altered sensory input. We examined input- and cell-type-specific changes in thalamo- and intracortical pathways during learning using an automated, home-cage sensory association training (SAT) paradigm coupling multi-whisker stimulation to a water reward. We found that the posterior medial nucleus (POm) but not the ventral posterior medial (VPM) nucleus of the thalamus drives increased cortical activity after 24 h of SAT, when behavioral evidence of learning first emerges. Synaptic strengthening within the POm thalamocortical pathway was first observed at thalamic inputs to L5 and was not generated by sensory stimulation alone. Synaptic changes in L2 were delayed relative to L5, requiring 48 h of SAT to drive synaptic plasticity at thalamic and intracortical inputs onto L2 Pyr neurons. These data identify the POm thalamocortical circuit as a site of rapid synaptic plasticity during learning and suggest a temporal sequence to learning-evoked synaptic changes in the sensory cortex.


Assuntos
Vias Aferentes/fisiologia , Aprendizagem/fisiologia , Plasticidade Neuronal/fisiologia , Células Receptoras Sensoriais/fisiologia , Córtex Somatossensorial/fisiologia , Tálamo/fisiologia , Animais , Macaca mulatta , Masculino , Modelos Neurológicos , Dinâmica não Linear , Amplitude de Movimento Articular/fisiologia , Vibrissas/inervação
18.
Soc Cogn Affect Neurosci ; 14(5): 559-568, 2019 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-31044241

RESUMO

In social interactions, people have to pay attention both to the 'what' and 'who'. In particular, expressive changes heard on speech signals have to be integrated with speaker identity, differentiating e.g. self- and other-produced signals. While previous research has shown that self-related visual information processing is facilitated compared to non-self stimuli, evidence in the auditory modality remains mixed. Here, we compared electroencephalography (EEG) responses to expressive changes in sequence of self- or other-produced speech sounds using a mismatch negativity (MMN) passive oddball paradigm. Critically, to control for speaker differences, we used programmable acoustic transformations to create voice deviants that differed from standards in exactly the same manner, making EEG responses to such deviations comparable between sequences. Our results indicate that expressive changes on a stranger's voice are highly prioritized in auditory processing compared to identical changes on the self-voice. Other-voice deviants generate earlier MMN onset responses and involve stronger cortical activations in a left motor and somatosensory network suggestive of an increased recruitment of resources for less internally predictable, and therefore perhaps more socially relevant, signals.


Assuntos
Felicidade , Voz , Eletroencefalografia , Potenciais Evocados , Feminino , Lateralidade Funcional/fisiologia , Humanos , Relações Interpessoais , Córtex Motor/fisiologia , Rede Nervosa/fisiologia , Desempenho Psicomotor , Córtex Somatossensorial/fisiologia , Adulto Jovem
19.
J Vis ; 19(5): 4, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31058990

RESUMO

Somatosensory perception is hampered on the moving limb during a goal-directed movement. This somatosensory suppression is mostly attributed to a forward model that predicts future states of the system based on the established motor command. Here, we examined whether and how this suppression is modulated by the predictability of object features important for controlling a grasping movement. Participants reached to grasp an object between thumb and index finger and then lifted it as straight as possible. Objects with symmetric or asymmetric mass distributions were presented either in a blocked or random manner, so that the object's mass distribution could be anticipated or not. At the moment of object contact, a brief vibrotactile stimulus of varying intensities was presented on the dorsal part of the moving index finger. Participants had to report whether they detected the stimulus. When the object's mass distribution was predictable, contact points with the object were modulated to the object's centre of mass. This modulation contributed to a minimized resultant object roll during lifting. When the object's mass distribution was unpredictable, participants chose a default grasping configuration, resulting in greater object roll for asymmetric mass distributions. Somatosensory perception was hampered when grasping both types of objects compared to baseline (no-movement). Importantly, somatosensory suppression was stronger when participants could predict the object's mass distribution. We suggest that the strength of somatosensory suppression depends on the predictability of movement-relevant object features.


Assuntos
Antecipação Psicológica/fisiologia , Percepção de Movimento/fisiologia , Movimento/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Feminino , Dedos/fisiologia , Força da Mão/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Somatossensorial/fisiologia , Adulto Jovem
20.
Cogn Neuropsychol ; 36(3-4): 103-116, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31076014

RESUMO

Electrical stimulation of the nervous system is a powerful tool for localizing and examining the function of numerous brain regions. Delivered to certain regions of the cerebral cortex, electrical stimulation can evoke a variety of first-order effects, including observable movements or an urge to move, or somatosensory, visual, or auditory percepts. In still other regions the subject may be oblivious to the stimulation. Often overlooked, however, is whether the subject is aware of the stimulation, and if so, how the stimulation is experienced by the subject. In this review of how electrical stimulation has been used to study selected aspects of sensorimotor and language function, we raise questions that future studies might address concerning the subjects' second-order experiences of intention and agency regarding evoked movements, of the naturalness of evoked sensory percepts, and of other qualia that might be evoked in the absence of an overt first-order experience.


Assuntos
Encéfalo/fisiopatologia , Estimulação Elétrica/métodos , Córtex Somatossensorial/fisiologia , Fala/fisiologia , Feminino , Humanos , Masculino
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