RESUMO
The concept of body schema has been introduced and widely discussed in the literature to explain various clinical observations and distortions in the body and space representation. Here we address the role of body schema related information in multi-joint limb motion. The processing of proprioceptive information may differ significantly in static and dynamic conditions since in the latter case the control system may employ specific dynamic rules and constraints. Accordingly, the perception of movement, e.g., estimation of step length and walking distance, may rely on a priori knowledge about intrinsic dynamics of limb segment motion and inherent relationships between gait parameters and body proportions. The findings are discussed in the general framework of space and body movement representation and suggest the existence of a dynamic locomotor body schema used for controlling step length and path estimation.
Assuntos
Marcha/fisiologia , Cinestesia/fisiologia , Orientação/fisiologia , Propriocepção/fisiologia , Caminhada/fisiologia , Fenômenos Biomecânicos , Imagem Corporal , Encéfalo/fisiologia , Humanos , Articulações/inervação , Músculo Esquelético/inervação , Analisadores Neurais/fisiologia , Desempenho Psicomotor/fisiologia , Medula Espinal/fisiologiaRESUMO
We investigated the adaptation of balancing behavior during a continuous, predictable perturbation of stance consisting of 3-min backward and forward horizontal sinusoidal oscillations of the support base. Two visual conditions (eyes-open, EO; eyes-closed, EC) and two oscillation frequencies (LF, 0.2 Hz; HF, 0.6 Hz) were used. Center of Mass (CoM) and Center of Pressure (CoP) oscillations and EMG of Soleus (Sol) and Tibialis Anterior (TA) were recorded. The time course of each variable was estimated through an exponential model. An adaptation index allowed comparison of the degree of adaptation of different variables. Muscle activity pattern was initially prominent under the more challenging conditions (HF, EC and EO; LF, EC) and diminished progressively to reach a steady state. At HF, the behavior of CoM and CoP was almost invariant. The time-constant of EMG adaptation was shorter for TA than for Sol. With EC, the adaptation index showed a larger decay in the TA than Sol activity at the end of the balancing trial, pointing to a different role of the two muscles in the adaptation process. At LF, CoM and CoP oscillations increased during the balancing trial to match the platform translations. This occurred regardless of the different EMG patterns under EO and EC. Contrary to CoM and CoP, the adaptation of the muscle activities had a similar time-course at both HF and LF, in spite of the two frequencies implying a different number of oscillation cycles. During adaptation, under critical balancing conditions (HF), postural muscle activity is tuned to that sufficient for keeping CoM within narrow limits. On the contrary, at LF, when vision permits, a similar decreasing pattern of muscle activity parallels a progressive increase in CoM oscillation amplitude, and the adaptive balancing behavior shifts from the initially reactive behavior to one of passive riding the platform. Adaptive balance control would rely on on-line computation of risk of falling and sensory inflow, while minimizing balance challenge and muscle effort. The results from this study contribute to the understanding of plasticity of the balance control mechanisms under posture-challenging conditions.
Assuntos
Contração Isométrica/fisiologia , Cinestesia/fisiologia , Músculo Esquelético/fisiologia , Orientação/fisiologia , Equilíbrio Postural/fisiologia , Percepção Visual/fisiologia , Suporte de Carga/fisiologia , Adulto , Fenômenos Biomecânicos , Eletromiografia , Feminino , Humanos , Masculino , Analisadores Neurais/fisiologia , Propriocepção/fisiologia , Privação Sensorial/fisiologia , Processamento de Sinais Assistido por Computador , Adulto JovemRESUMO
Impairment of postural control is a common consequence of Parkinson's disease (PD). Increasing evidences demonstrate that the pathophysiology of postural disorders in PD includes deficits in proprioceptive processing and integration. However, the nature of these deficits has not been thoroughly examined. We propose to establish a link between proprioceptive impairments and postural deficits in PD using two different experimental approaches manipulating proprioceptive information. In the first one, the subjects stood on a platform that tilted slowly with oscillatory angular movements in the frontal or sagittal planes. The amplitude and frequency of these movements were kept below the semicircular canal perception threshold. Subjects were asked to maintain vertical body posture with and without vision. The orientations of body segments were analyzed. In the second one, the postural control was tested using the tendon-vibration method, which is known to generate illusory movement sensations and postural reactions. Vibrations were applied to ankle muscles. The subject's whole-body motor responses were analyzed from center of pressure displacements. In the first experiment, the parkinsonian patients (PP) were unable to maintain the vertical trunk orientation without vision. Their performances with vision improved, without fully reaching the level of control subjects (CS). In the second experiment, the postural reactions of the PP were similar to those of the CS at the beginning of the perturbation and increased drastically at the end of the perturbation's period as compared to those of CS and could induce fall. These results will bring new concepts to the sensorimotor postural control, to the physiopathology of posture, equilibrium and falls in PD and to the role of basal ganglia pathways in proprioception integration. Nevertheless, in order to assess precisely the role played by sensorimotor integration deficits in postural impairments in PD, further studies establishing the links between clinical features and abnormalities are now required.
Assuntos
Cinestesia/fisiologia , Orientação/fisiologia , Equilíbrio Postural/fisiologia , Postura/fisiologia , Propriocepção/fisiologia , Suporte de Carga/fisiologia , Acidentes por Quedas , Tendão do Calcâneo/fisiopatologia , Idoso , Gânglios da Base/fisiopatologia , Fenômenos Biomecânicos/fisiologia , Feminino , Humanos , Ilusões , Masculino , Pessoa de Meia-Idade , Analisadores Neurais/fisiologia , Estimulação Física , Privação Sensorial/fisiologia , VibraçãoRESUMO
Sudden addition or removal of visual information can be particularly critical to balance control. The promptness of adaptation of stance control mechanisms is quantified by the latency at which body oscillation and postural muscle activity vary after a shift in visual condition. In the present study, volunteers stood on a force platform with feet parallel or in tandem. Shifts in visual condition were produced by electronic spectacles. Ground reaction force (center of foot pressure, CoP) and EMG of leg postural muscles were acquired, and latency of CoP and EMG changes estimated by t-tests on the averaged traces. Time-to-reach steady-state was estimated by means of an exponential model. On allowing or occluding vision, decrements and increments in CoP position and oscillation occurred within about 2s. These were preceded by changes in muscle activity, regardless of visual-shift direction, foot position or front or rear leg in tandem. These time intervals were longer than simple reaction-time responses. The time course of recovery to steady-state was about 3s, shorter for oscillation than position. The capacity of modifying balance control at very short intervals both during quiet standing and under more critical balance conditions speaks in favor of a necessary coupling between vision, postural reference, and postural muscle activity, and of the swiftness of this sensory reweighing process.
Assuntos
Retroalimentação Sensorial/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Tempo de Reação/fisiologia , Privação Sensorial/fisiologia , Percepção Visual/fisiologia , Adulto , Eletromiografia , Feminino , Humanos , Masculino , Neurônios Motores/fisiologia , Analisadores Neurais/fisiologia , Células Receptoras Sensoriais/fisiologia , Suporte de Carga/fisiologiaRESUMO
The control of postural sway depends on the dynamic integration of multi-sensory information in the central nervous system. Augmentation of sensory information, such as during auditory biofeedback (ABF) of the trunk acceleration, has been shown to improve postural control. By means of quantitative electroencephalography (EEG), we examined the basic processes in the brain that are involved in the perception and cognition of auditory signals used for ABF. ABF and Fake ABF (FAKE) auditory stimulations were delivered to 10 healthy naive participants during quiet standing postural tasks, with eyes-open and closed. Trunk acceleration and 19-channels EEG were recorded at the same time. Advanced, state-of-the-art EEG analysis and modeling methods were employed to assess the possibly differential, functional activation, and localization of EEG spectral features (power in α, ß, and γ bands) between the FAKE and the ABF conditions, for both the eyes-open and the eyes-closed tasks. Participants gained advantage by ABF in reducing their postural sway, as measured by a reduction of the root mean square of trunk acceleration during the ABF compared to the FAKE condition. Population-wise localization analysis performed on the comparison FAKE - ABF revealed: (i) a significant decrease of α power in the right inferior parietal cortex for the eyes-open task; (ii) a significant increase of γ power in left temporo-parietal areas for the eyes-closed task; (iii) a significant increase of γ power in the left temporo-occipital areas in the eyes-open task. EEG outcomes supported the idea that ABF for postural control heavily modulates (increases) the cortical activation in healthy participants. The sites showing the higher ABF-related modulation are among the known cortical areas associated with multi-sensory, perceptual integration, and sensorimotor integration, showing a differential activation between the eyes-open and eyes-closed conditions.
Assuntos
Percepção Auditiva/fisiologia , Biorretroalimentação Psicológica/fisiologia , Córtex Cerebral/fisiologia , Eletroencefalografia , Cinestesia/fisiologia , Equilíbrio Postural/fisiologia , Postura/fisiologia , Processamento de Sinais Assistido por Computador , Estimulação Acústica , Adulto , Idoso , Algoritmos , Mapeamento Encefálico , Feminino , Análise de Fourier , Humanos , Masculino , Pessoa de Meia-Idade , Analisadores Neurais/fisiologia , Propriocepção/fisiologia , Privação Sensorial/fisiologiaRESUMO
Investigation into the functional activity of the acoustic and visual analyzer has been carried out before and after procedures of listening to one's own EEG of the temporal and occipital cortex areas. It has been shown, that there is a dependence of the dynamics of latent periods of sensomotor response to modality of stimuli and localization of source of the EEG acoustic image. After listening to acoustic image of the temporal EEG, a reduction of sensomotor reaction latency in the acoustic test has been observed. After listening to acoustic image of the occipital EEC, a reduction of sensomotor reaction latency in the visual test has been observed. In the control session after listening to A. Vivaldi's music, no significant shifts of sensomotor reaction latency have been observed. A conclusion has been made that, under conditions of local EEG-acoustic feedback, there is a selective elevation of functional activity of the brain areas used as the EEG-source for acoustic image forming.
Assuntos
Percepção Auditiva/fisiologia , Eletroencefalografia , Analisadores Neurais/fisiologia , Lobo Occipital/fisiologia , Lobo Temporal/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Multisensory integration in humans is thought to be essentially a brain phenomenon, but theories are silent as to the possible involvement of the peripheral nervous system. We provide evidence that this approach is insufficient. We report novel tactile-auditory and tactile-visual interactions in humans, demonstrating that a facilitating sound or visual stimulus that is exactly synchronous with an excitatory tactile signal presented at the lower leg increases the peripheral representation of that excitatory signal. These results demonstrate that during multisensory integration, the brain not only continuously binds information obtained from the senses, but also acts directly on that information by modulating activity at peripheral levels. We also discuss a theoretical framework to explain this novel interaction.
Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Córtex Cerebral/fisiologia , Nervos Periféricos/fisiologia , Tato/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Condicionamento Psicológico/fisiologia , Eletromiografia , Feminino , Humanos , Perna (Membro)/inervação , Masculino , Pessoa de Meia-Idade , Analisadores Neurais/fisiologia , Estimulação Luminosa , Limiar Sensorial/fisiologiaRESUMO
Current progress in the cognitive and affective neurosciences is constantly influencing the development of psychoanalytic theory and practice. However, despite the emerging dialogue between neuroscience and psychoanalysis, the neuronal processes underlying psychoanalytic constructs such as defense mechanisms remain unclear. One of the main problems in investigating the psychodynamic-neuronal relationship consists in systematically linking the individual contents of first-person subjective experience to third-person observation of neuronal states. We therefore introduced an appropriate methodological strategy, 'first-person neuroscience', which aims at developing methods for systematically linking first- and third-person data. The utility of first-person neuroscience can be demonstrated by the example of the defense mechanism of sensorimotor regression as paradigmatically observed in catatonia. Combined psychodynamic and imaging studies suggest that sensorimotor regression might be associated with dysfunction in the neural network including the orbitofrontal, the medial prefrontal and the premotor cortices. In general sensorimotor regression and other defense mechanisms are psychoanalytic constructs that are hypothesized to be complex emotional-cognitive constellations. In this paper we suggest that specific functional mechanisms which integrate neuronal activity across several brain regions (i.e. neuronal integration) are the physiological substrates of defense mechanisms. We conclude that first-person neuroscience could be an appropriate methodological strategy for opening the door to a better understanding of the neuronal processes of defense mechanisms and their modulation in psychoanalytic psychotherapy.
Assuntos
Córtex Cerebral/fisiopatologia , Mecanismos de Defesa , Individualidade , Teoria Psicanalítica , Terapia Psicanalítica , Catatonia/fisiopatologia , Catatonia/psicologia , Cognição/fisiologia , Transtorno Conversivo/fisiopatologia , Transtorno Conversivo/psicologia , Diagnóstico por Imagem , Emoções/fisiologia , Humanos , Rede Nervosa/fisiopatologia , Analisadores Neurais/fisiologia , Relações Médico-Paciente , Regressão PsicológicaRESUMO
The insular cortex is located in the centre of the cerebral hemisphere, having connections with the primary and secondary somatosensory areas, anterior cingulate cortex, amygdaloid body, prefrontal cortex, superior temporal gyrus, temporal pole, orbitofrontal cortex, frontal and parietal opercula, primary and association auditory cortices, visual association cortex, olfactory bulb, hippocampus, entorhinal cortex, and motor cortex. Accordingly, dense connections exist among insular cortex neurons. The insular cortex is involved in the processing of visceral sensory, visceral motor, vestibular, attention, pain, emotion, verbal, motor information, inputs related to music and eating, in addition to gustatory, olfactory, visual, auditory, and tactile data. In this article, the literature on the relationship between the insular cortex and neuropsychiatric disorders was summarized following a computer search of the Pub-Med database. Recent neuroimaging data, including voxel based morphometry, PET and fMRI, revealed that the insular cortex was involved in various neuropsychiatric diseases such as mood disorders, panic disorders, PTSD, obsessive-compulsive disorders, eating disorders, and schizophrenia. Investigations of functions and connections of the insular cortex suggest that sensory information including gustatory, olfactory, visual, auditory, and tactile inputs converge on the insular cortex, and that these multimodal sensory information may be integrated there.
Assuntos
Córtex Cerebral/fisiopatologia , Transtornos Mentais/fisiopatologia , Transtornos de Ansiedade/diagnóstico , Transtornos de Ansiedade/fisiopatologia , Transtornos de Ansiedade/psicologia , Encéfalo/fisiopatologia , Transtornos da Alimentação e da Ingestão de Alimentos/diagnóstico , Transtornos da Alimentação e da Ingestão de Alimentos/fisiopatologia , Transtornos da Alimentação e da Ingestão de Alimentos/psicologia , Humanos , Imageamento por Ressonância Magnética , Transtornos Mentais/diagnóstico , Transtornos Mentais/psicologia , Transtornos do Humor/diagnóstico , Transtornos do Humor/fisiopatologia , Transtornos do Humor/psicologia , Rede Nervosa/fisiopatologia , Analisadores Neurais/fisiologia , Vias Neurais/fisiopatologia , Transtorno Obsessivo-Compulsivo/diagnóstico , Transtorno Obsessivo-Compulsivo/fisiopatologia , Transtorno Obsessivo-Compulsivo/psicologia , Percepção/fisiologia , Tomografia por Emissão de Pósitrons , Esquizofrenia/diagnóstico , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Sensação/fisiologia , Transtornos de Estresse Pós-Traumáticos/diagnóstico , Transtornos de Estresse Pós-Traumáticos/fisiopatologia , Transtornos de Estresse Pós-Traumáticos/psicologiaAssuntos
Córtex Cerebral/fisiologia , Córtex Cerebral/fisiopatologia , Potenciais Somatossensoriais Evocados , Hemiplegia/fisiopatologia , Células do Corno Posterior/fisiologia , Células do Corno Posterior/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Analisadores Neurais/fisiologia , Analisadores Neurais/fisiopatologia , Pele/inervaçãoRESUMO
Microelectrophysiological and computer techniques were used in the study of background impulse activity (BIA) of the internal geniculate body (IGB) neurons and mesencephalic inferior tubers (MIT) of white rats. Definite differences were found in BIA by regularity, dynamic types and modality of interimpulse histograms. Mean frequency of MIT neuron discharges was 16-17 Hz and was about 3 times higher than in neurons of the IGB. Intraperitoneal injection of taurin noticeably suppressed neuronal activity in both nuclei. The drug reduced mean frequency of background impulse discharges both in MIT and IGB. Thus, taurin produces primarily suppressing modulating effect on neuronal activity of IGB and MIT.
Assuntos
Núcleo Coclear/efeitos dos fármacos , Corpos Geniculados/efeitos dos fármacos , Corpos Geniculados/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Taurina/farmacologia , Teto do Mesencéfalo/efeitos dos fármacos , Teto do Mesencéfalo/fisiologia , Potenciais de Ação/fisiologia , Animais , Núcleo Coclear/fisiologia , Computadores , Interpretação Estatística de Dados , Eletrofisiologia , Injeções Intraperitoneais , Microeletrodos , Analisadores Neurais/fisiologia , Ratos , Taurina/administração & dosagemRESUMO
We present a computational model that learns a coupling between motor parameters and their sensory consequences in vocal production during a babbling phase. Based on the coupling, preferred motor parameters and prototypically perceived sounds develop concurrently. Exposure to an ambient language modifies perception to coincide with the sounds from the language. The model develops motor mirror neurons that are active when an external sound is perceived. An extension to visual mirror neurons for oral gestures is suggested.
Assuntos
Encéfalo/fisiologia , Desenvolvimento da Linguagem , Modelos Neurológicos , Rede Nervosa/fisiologia , Redes Neurais de Computação , Desempenho Psicomotor/fisiologia , Percepção da Fala/fisiologia , Fala/fisiologia , Percepção Visual/fisiologia , Inteligência Artificial , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Humanos , Comportamento Imitativo/fisiologia , Lactente , Músculos Laríngeos/inervação , Neurônios Motores/fisiologia , Analisadores Neurais/fisiologia , Neurônios/fisiologia , Músculos Faríngeos/inervação , Fonética , SemânticaRESUMO
The paper presents a computational model of language in which linguistic abilities evolve in organisms that interact with an environment. Each individual's behavior is controlled by a neural network and we study the consequences in the network's internal functional organization of learning to process different classes of words. Agents are selected for reproduction according to their ability to manipulate objects and to understand nouns (objects' names) and verbs (manipulation tasks). The weights of the agents' neural networks are evolved using a genetic algorithm. Synthetic brain imaging techniques are then used to examine the functional organization of the neural networks. Results show that nouns produce more integrated neural activity in the sensory-processing hidden layer, while verbs produce more integrated synaptic activity in the layer where sensory information is integrated with proprioceptive input. Such findings are qualitatively compared with human brain imaging data that indicate that nouns activate more the posterior areas of the brain related to sensory and associative processing, while verbs activate more the anterior motor areas.
Assuntos
Encéfalo/fisiologia , Desenvolvimento da Linguagem , Rede Nervosa/fisiologia , Redes Neurais de Computação , Desempenho Psicomotor/fisiologia , Semântica , Percepção da Fala/fisiologia , Algoritmos , Animais , Inteligência Artificial , Percepção Auditiva/fisiologia , Evolução Biológica , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Simulação por Computador , Humanos , Analisadores Neurais/fisiologia , Neurônios/fisiologia , Psicolinguística , Percepção Visual/fisiologiaRESUMO
The authors present a neurological theory of how cognitive information and emotional information are integrated in the nucleus accumbens during effective decision making. They describe how the nucleus accumbens acts as a gateway to integrate cognitive information from the ventromedial prefrontal cortex and the hippocampus with emotional information from the amygdala. The authors have modeled this integration by a network of spiking artificial neurons organized into separate areas and used this computational model to simulate 2 kinds of cognitive-affective integration. The model simulates successful performance by people with normal cognitive-affective integration. The model also simulates the historical case of Phineas Gage as well as subsequent patients whose ability to make decisions became impeded by damage to the ventromedial prefrontal cortex.
Assuntos
Afeto/fisiologia , Cognição/fisiologia , Tomada de Decisões/fisiologia , Redes Neurais de Computação , Núcleo Accumbens/fisiologia , Resolução de Problemas/fisiologia , Tonsila do Cerebelo/fisiologia , Nível de Alerta/fisiologia , Emoções/fisiologia , Potenciais Evocados , Hipocampo/fisiologia , Humanos , Rede Nervosa/fisiologia , Analisadores Neurais/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Córtex Pré-Frontal/fisiologia , Área Tegmentar Ventral/fisiologiaRESUMO
Auditory scene analysis involves the simultaneous grouping and parsing of acoustic data into separate mental representations (i.e., objects). Over two experiments, we examined the sequence of neural processes underlying concurrent sound segregation by means of recording of human middle latency auditory evoked responses. Participants were presented with complex sounds comprising several harmonics, one of which could be mistuned such that it was not an integer multiple of the fundamental frequency. In both experiments, Na (approximately 22 ms) and Pa (approximately 32 ms) waves were reliably generated for all classes of stimuli. For stimuli with a fundamental frequency of 200 Hz, the mean Pa amplitude was significantly larger when the third harmonic was mistuned by 16% of its original value, relative to when it was tuned. The enhanced Pa amplitude was related to an increased likelihood in reporting the presence of concurrent auditory objects. Our results are consistent with a low-level stage of auditory scene analysis in which acoustic properties such as mistuning act as preattentive segregation cues that can subsequently lead to the perception of multiple auditory objects.
Assuntos
Atenção/fisiologia , Córtex Auditivo/fisiologia , Percepção Auditiva/fisiologia , Adulto , Vias Auditivas/fisiologia , Mapeamento Encefálico , Potenciais Evocados Auditivos/fisiologia , Feminino , Lobo Frontal/fisiologia , Humanos , Masculino , Analisadores Neurais/fisiologia , Lobo Parietal/fisiologia , Percepção da Altura Sonora/fisiologia , Tempo de Reação/fisiologia , Espectrografia do Som , Lobo Temporal/fisiologiaRESUMO
To quantify performance of the goldfish oculomotor neural integrator and determine its dependence on visual feedback, we measured the relationship between eye drift-velocity and position during spontaneous gaze fixations in the light and in the dark. In the light, drift-velocities were typically less than 1 deg/s, similar to those observed in humans. During brief periods in darkness, drift-velocities were only slightly larger, but showed greater variance. One hour in darkness degraded fixation-holding performance. These findings suggest that while visual feedback is not essential for online fixation stability, it may be used to tune the mechanism of persistent neural activity in the oculomotor integrator.
Assuntos
Movimentos Oculares/fisiologia , Retroalimentação Psicológica , Carpa Dourada/fisiologia , Analisadores Neurais/fisiologia , Nervo Oculomotor/fisiologia , Animais , NeuropsicologiaRESUMO
To have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting our world, possesses an ontology too. It creates primitives and makes existence assumptions. It decomposes target space in a way that exhibits a certain invariance, which in turn is functionally significant. We will investigate which are the functional regularities guiding this decomposition process, by answering to the following questions: What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brain's motor output and its representational deep structure, in particular of the conscious mind arising from it (its "phenomenal output")? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results and integrating them with a wider philosophical perspective, we will emphasize the contribution the motor system makes to this process. As it will be shown, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence demonstrates that the brain models movements and action goals in terms of multimodal representations of organism-object-relations. Under a representationalist analysis, this process can be conceived of as an internal, dynamic representation of the intentionality-relation itself. We will show how such a complex form of representational content, once it is in place, can later function as a functional building block for social cognition and for a more complex, consciously experienced representation of the first-person perspective as well.
Assuntos
Encéfalo/fisiologia , Estado de Consciência/fisiologia , Ego , Psicologia do Self , Animais , Percepção Auditiva/fisiologia , Conscientização/fisiologia , Mapeamento Encefálico , Haplorrinos , Humanos , Intenção , Controle Interno-Externo , Relações Interpessoais , Analisadores Neurais/fisiologia , Neurônios/fisiologia , Resolução de Problemas/fisiologia , Desempenho Psicomotor/fisiologia , Especificidade da Espécie , Percepção Visual/fisiologiaRESUMO
The influence of surgeries in the carotid arteries produced on the visual functions and ocular blood circulation was studied in patients with ocular ischemic syndrome (OIS) during the remote postoperative period. A total of 180 patients with OIS (including 104 patients with an acute OIS clinical course and 76 patients with primary chronic clinical course) and with a pronounced stenosis of the carotid arteries were examined preoperatively and postoperatively within 1 or 2 years. A reliably improved visual acuity (preoperatively -0.37 +/- 0.05; and postoperatively -0.52 +/- 0.07; p < 0.01), positive dynamics in the electric sensitivity threshold and in a lability of the optic nerve were observed in patients with the acute OIS clinical course after reconstructive surgeries in the carotid arteries. An increase in contrast sensitivity of the visual analyzer was detected in 28.8% of patients with the acute clinical course and in 10.5% of patients with the chronic OIS clinical course. An improved blood circulation through the ocular artery was stated in patients of both groups. Reconstructive surgeries in the carotid arteries are most effective in correcting the acute OIS clinical variation.
Assuntos
Amaurose Fugaz/etiologia , Estenose das Carótidas/complicações , Estenose das Carótidas/cirurgia , Olho/irrigação sanguínea , Isquemia/cirurgia , Artéria Oftálmica , Oclusão da Artéria Retiniana/complicações , Doença Aguda , Estenose das Carótidas/diagnóstico , Sensibilidades de Contraste , Feminino , Seguimentos , Glaucoma de Ângulo Aberto/complicações , Humanos , Isquemia/etiologia , Masculino , Pessoa de Meia-Idade , Analisadores Neurais/fisiologia , Artéria Oftálmica/fisiologia , Nervo Óptico/fisiologia , Doenças do Nervo Óptico/complicações , Oclusão da Artéria Retiniana/diagnóstico por imagem , Doenças Retinianas/complicações , Síndrome , Fatores de Tempo , Ultrassonografia Doppler , Acuidade VisualRESUMO
Pain is processed in multiple brain areas, indicating the complexity of pain perception. The ability to locate pain plays a pivotal role in immediate defense and withdrawal behavior. However, how the brain localizes nociceptive information without additional information from somatotopically organized mechano-receptive pathways is not well understood. We used single-trial functional magnetic resonance imaging (fMRI) to assess hemodynamic responses to right and left painful stimulation. Thulium-YAG-(yttrium-aluminium-granate)-laser-evoked pain stimuli, without concomitant tactile component, were applied to either hand in a randomized order. A contralateral bias of the BOLD response was investigated to determine areas involved in the coding of the side of stimulation, which we observed in primary (SI) and secondary (SII) somatosensory cortex, insula, and the thalamus. This suggests that these structures provide spatial information of selective nociceptive stimuli. More importantly, this contralateral bias of activation allowed functionally segregated activations within the SII complex, the insula, and the thalamus. Only distinct subregions of the SII complex, the posterior insula and the lateral thalamus, but not the remaining SII complex, the anterior insula and the medial thalamus, showed a contralaterally biased representation of painful stimuli. This result supports the hypothesis that sensory-discriminative attributes of painful stimuli, such as those related to body side, are topospecifically represented within the forebrain projections of the nociceptive system and highlights the concept of functional segregation and specialization within these structures.