RESUMEN
How does the brain simultaneously process signals that bring complementary information, like raw sensory signals and their transformed counterparts, without any disruptive interference? Contemporary research underscores the brain's adeptness in using decorrelated responses to reduce such interference. Both neurophysiological findings and artificial neural networks support the notion of orthogonal representation for signal differentiation and parallel processing. Yet, where, and how raw sensory signals are transformed into more abstract representations remains unclear. Using a temporal pattern discrimination task in trained monkeys, we revealed that the second somatosensory cortex (S2) efficiently segregates faithful and transformed neural responses into orthogonal subspaces. Importantly, S2 population encoding for transformed signals, but not for faithful ones, disappeared during a nondemanding version of this task, which suggests that signal transformation and their decoding from downstream areas are only active on-demand. A mechanistic computation model points to gain modulation as a possible biological mechanism for the observed context-dependent computation. Furthermore, individual neural activities that underlie the orthogonal population representations exhibited a continuum of responses, with no well-determined clusters. These findings advocate that the brain, while employing a continuum of heterogeneous neural responses, splits population signals into orthogonal subspaces in a context-dependent fashion to enhance robustness, performance, and improve coding efficiency.
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Macaca mulatta , Corteza Somatosensorial , Animales , Corteza Somatosensorial/fisiología , Modelos Neurológicos , MasculinoRESUMEN
Autism spectrum disorder (ASD) is characterized by impaired social communication and interaction associated with repetitive or stereotyped behaviour. Prenatal valproic acid (VPA) exposure in rodents is a commonly used model of ASD. Resveratrol (RSV) has been shown to prevent interneuronal and behavioural impairments in the VPA model. We investigated the effects of prenatal VPA exposure and RSV on the GABAergic synaptic transmission, brain oscillations and on the genic expression of interneuron-associated transcription factor LHX6 in the primary somatosensory area (PSSA). Prenatal VPA exposure decreased the sIPSC and mIPSC frequencies and the sIPSC decay kinetics onto layers 4/5 pyramidal cells of PSSA. About 40% of VPA animals exhibited absence-like spike-wave discharge (SWD) events associated with behaviour arrest and increased power spectrum density of delta, beta and gamma cortical oscillations. VPA animals had reduced LHX6 expression in PSSA, but VPA animals treated with RSV had no changes on synaptic inhibition or LHX6 expression in the PSSA. SWD events associated with behaviour arrest and the abnormal increment of cortical oscillations were also absent in VPA animals treated with RSV. These findings provide new venues to investigate the role of both RSV and VPA in the pathophysiology of ASD and highlight the VPA animal model as an interesting tool to investigate pathways related to the aetiology and possible future therapies to this neuropsychiatric disorder.
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Trastorno del Espectro Autista , Efectos Tardíos de la Exposición Prenatal , Animales , Femenino , Embarazo , Ratas , Conducta Animal , Modelos Animales de Enfermedad , Resveratrol/farmacología , Roedores , Conducta Social , Corteza Somatosensorial , Transmisión Sináptica , Ácido Valproico/farmacologíaRESUMEN
INTRODUCTION: The study of non-laboratory species has been part of a broader effort to establish the basic organization of the mammalian neocortex, as these species may provide unique insights relevant to cortical organization, function, and evolution. METHODS: In the present study, the organization of three somatosensory cortical areas of the medium-sized (5-11 kg body mass) Amazonian rodent, the paca (Cuniculus paca), was determined using a combination of electrophysiological microelectrode mapping and histochemical techniques (cytochrome oxidase and NADPH diaphorase) in tangential sections. RESULTS: Electrophysiological mapping revealed a somatotopically organized primary somatosensory cortical area (S1) located in the rostral parietal cortex with a characteristic foot-medial/head-lateral contralateral body surface representation similar to that found in other species. S1 was bordered laterally by two regions housing neurons responsive to tactile stimuli, presumably the secondary somatosensory (S2) and parietal ventral (PV) cortical areas that evinced a mirror-reversal representation (relative to S1) of the contralateral body surface. The limits of the putative primary visual (V1) and primary auditory (A1) cortical areas, as well as the complete representation of the contralateral body surface in S1, were determined indirectly by the histochemical stains. Like the barrel field described in small rodents, we identified a modular arrangement located in the face representation of S1. CONCLUSIONS: The relative location, somatotopic organization, and pattern of neuropil histochemical reactivity in the three paca somatosensory cortical areas investigated are similar to those described in other mammalian species, providing additional evidence of a common plan of organization for the somatosensory cortex in the rostral parietal cortex of mammals.
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Cuniculidae , Corteza Somatosensorial , Animales , Corteza Somatosensorial/fisiología , Roedores , Lóbulo Parietal/fisiología , Mapeo Encefálico , América del SurRESUMEN
Do sensory cortices process more than one sensory modality? To answer these questions, scientists have generated a wide variety of studies at distinct space-time scales in different animal models, and often shown contradictory conclusions. Some conclude that this process occurs in early sensory cortices, but others that this occurs in areas central to sensory cortices. Here, we sought to determine whether sensory neurons process and encode physical stimulus properties of different modalities (tactile and acoustic). For this, we designed a bimodal detection task where the senses of touch and hearing compete from trial to trial. Two Rhesus monkeys performed this novel task, while neural activity was recorded in areas 3b and 1 of the primary somatosensory cortex (S1). We analyzed neurons' coding properties and variability, organizing them by their receptive field's position relative to the stimulation zone. Our results indicate that neurons of areas 3b and 1 are unimodal, encoding only the tactile modality in both the firing rate and variability. Moreover, we found that neurons in area 3b carried more information about the periodic stimulus structure than those in area 1, possessed lower response and coding latencies, and had a lower intrinsic time scale. In sum, these differences reveal a hidden processing-based hierarchy. Finally, using a powerful nonlinear dimensionality reduction algorithm, we show that the activity from areas 3b and 1 can be separated, establishing a clear division in the functionality of these two subareas of S1.
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Corteza Somatosensorial , Percepción del Tacto , Animales , Corteza Somatosensorial/fisiología , Percepción del Tacto/fisiología , Tacto , Lóbulo Parietal , Células Receptoras SensorialesRESUMEN
Toxoplasma gondii is able to manipulate the host immune system to establish a persistent and efficient infection, contributing to the development of brain abnormalities with behavioral repercussions. In this context, this work aimed to evaluate the effects of T. gondii infection on the systemic inflammatory response and structure of the primary somatosensory cortex (PSC). C57BL/6 and BALB/c mice were infected with T. gondii ME49 strain tissue cysts and accompanied for 30 days. After this period, levels of cytokines IFN-γ, IL-12, TNF-α and TGF-ß were measured. After blood collection, mice were perfused and the brains were submitted to immunohistochemistry for perineuronal net (PNN) evaluation and cyst quantification. The results showed that C57BL/6 mice presented higher levels of TNF-α and IL-12, while the levels of TGF-ß were similar between the two mouse lineages, associated with the elevated number of tissue cysts, with a higher occurrence of cysts in the posterior area of the PSC when compared to BALB/c mice, which presented a more homogeneous cyst distribution. Immunohistochemistry analysis revealed a greater loss of PNN labeling in C57BL/6 animals compared to BALB/c. These data raised a discussion about the ability of T. gondii to stimulate a systemic inflammatory response capable of indirectly interfering in the brain structure and function.
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Corteza Somatosensorial , Síndrome de Respuesta Inflamatoria Sistémica , Toxoplasma , Toxoplasmosis , Animales , Ratones , Interleucina-12/metabolismo , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Corteza Somatosensorial/inmunología , Corteza Somatosensorial/parasitología , Síndrome de Respuesta Inflamatoria Sistémica/inmunología , Síndrome de Respuesta Inflamatoria Sistémica/parasitología , Toxoplasma/patogenicidad , Toxoplasmosis/inmunología , Toxoplasmosis/parasitología , Factor de Crecimiento Transformador beta/metabolismo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
AIMS: Mitochondrial (mt) DNA replication is strongly associated with oxidative stress, a condition triggered by aging and hyperglycemia, both of which contribute to mitophagy disruption and inflammation. This observational exploratory study evaluated mtDNA-copy number (mtDNA-CN) and expression of genes involved in mitochondriogenesis (PPARGC1A, TFAM, TFB1M, TFB2M), mitophagy (PINK1, PRKN), and inflammatory pathways triggered by hyperglycemia (TXNIP, NLRP3, NFKB1), in the postcentral gyrus of adults and older individuals with and without type 2 diabetes mellitus (T2D). MAIN METHODS: Quantitative real-time PCR was employed to evaluate mtDNA-CN and gene expression; tissue autofluorescence, a marker of aging and of cells with damaged organelles, was also quantified. KEY FINDINGS: No correlation was found between age and mtDNA-CN, but a direct correlation was observed for cases with mtDNA-CN >1000 (r = 0.41). The mtDNA-CN >1000 group had greater tissue autofluorescence and higher body mass index compared to the mtDNA-CN <1000 group (BMI; 25.7 vs 22.0 kg/m2, respectively). mtDNA-CN correlated with tissue autofluorescence in the overall sample (r = 0.55) and in the T2D group (r = 0.64). PINK and PRKN expressions were inversely correlated with age. Mitochondriogenesis genes and TXNIP expressions were higher in the T2D group, and correlations among the mitochondriogenesis genes were also stronger in this group, relative to the subgroup with mtDNA-CN >1000.
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Diabetes Mellitus Tipo 2 , Hiperglucemia , Envejecimiento/genética , Índice de Masa Corporal , Variaciones en el Número de Copia de ADN , ADN Mitocondrial/genética , ADN Mitocondrial/metabolismo , Diabetes Mellitus Tipo 2/genética , Humanos , Proteína con Dominio Pirina 3 de la Familia NLR , Proteínas Quinasas/genética , Proteínas Quinasas/metabolismo , Corteza Somatosensorial/metabolismoRESUMEN
Este estudo teve como objetivo analisar o efeito imediato da prática de dança de salão sobre o controle postural estático de seus praticantes, juntamente aos fatores que possam influenciá-lo. Optou-se por um estudo transversal de caráter observacional quantitativo em uma amostra por conveniência, constituída por 19 homens e 19 mulheres praticantes de dança de salão, que participaram de uma prática de dança de 120 minutos. Foram coletados os dados sociodemográficos, antropométricos e sintomas osteomusculares. Para a avaliação do centro de pressão (COP), foi utilizado uma plataforma de força antes e depois da prática. O único fator que demonstrou diferença significativa no controle postural antes da prática de dança foi o sexo, sendo os homens que apresentam maiores deslocamentos no COP. Comparando o efeito da prática de 120 minutos de dança, em todos os participantes, houve uma diminuição do deslocamento do COP na posição bipodal no COPap (p= 0.028) e COPvel (p= 0.003), na posição unipodal COPvel (p= 0.006) e na posição semi-tandem COPml (p= 0.026). O efeito imediato de uma prática de dança de salão contribui para o controle postural em ambos os sexos. (AU)
This study aimed to analyze the immediate effect of the practice ballroom dancing on the static postural control of its practitioners, along with factors that can influence it. We opted for a cross-sectional study of quantitative observational in a sample of convenience of 19 men and 19 women practitioner's ballroom dancing, who participated in a dance practice about 120 minutes. We collected sociodemographic data, anthropometric and musculoskeletal symptoms. For the evaluation of center of pressure (COP), was used a force platform before and after practice. The only factor that demonstrated a significant association with postural control prior to dance practice was the genre, men show greater displacements at the COP. Comparing the effect of the practice of 120 minutes of dance, in all participants, a decrease in COP displacement in the bipedal position in COPap (p = 0.028) and COPvel (p = 0.003), in the single-leg position COPvel (p = 0.006) and in the semi-tandem position COPml (p = 0.026). The immediate effect of a ballroom practice contributes to postural control in both sexes. (AU)
Asunto(s)
Humanos , Masculino , Femenino , Adolescente , Adulto , Adulto Joven , Adulto , Danzaterapia , Baile , Equilibrio Postural , Corteza Somatosensorial , Mujeres , Sistema Nervioso Central , Antropometría , Extremidad Inferior , Estabilidad Central , Pierna , Hombres , MovimientoRESUMEN
A dor neuropática é causada por uma lesão ou doença do sistema nervoso somatossensitivo. Trata-se de uma manifestação sindrômica que envolve mecanismos inflamatórios e imunes com fisiopatologia ainda pouco esclarecida. O espectro de apresentação da dor neuropática é amplo e, assim, constitui um desafio na prática clínica. Este problema de saúde pública necessita de ampla capacidade técnica dos clínicos generalistas. Torna-se relevante identificar o potencial de cronificação do sintoma e adotar abordagens mitigantes do processo lesivo, estrutural e emocional. Nesse sentido, o diagnóstico adequado da dor neuropática é o primeiro passo na abordagem ao paciente. Diante disso, essa revisão objetiva facilitar a melhor escolha dos métodos diagnósticos no manejo clínico do paciente. Dentre estes, é possível citar a imagem por ressonância magnética funcional, eletroneuromiografia, tomografia por emissão de pósitrons, microneurografia, teste quantitativo sensorial, biópsias de pele, estudos de condução nervosa e de potencial somatossensorial evocado. A dor, por ser um processo sensorial subjetivo, apresenta amplo espectro de manifestações clínicas. Por essa razão, é possível fazer uso de técnicas como métodos de triagem e exames complementares para um diagnóstico mais específico.
Neuropathic pain is caused by an injury or illness of the somatosensory nervous system. It is a syndromic manifestation that involves inflammatory and immune mechanisms, whose pathophysiology is still poorly understood. The spectrum of presentation of neuropathic pain is wide and, therefore, it is a challenge in clinical practice. This public health problem requires the broad technical capacity of general practitioners. It is relevant to identify the potential for chronicity of the symptom and adopt mitigating approaches to the harmful, structural, and emotional process. In this sense, the proper diagnosis of neuropathic pain is the first step in approaching the patient. Therefore, this review aims to facilitate the best choice of diagnostic methods in the clinical management of the patient. Among these, functional magnetic resonance imaging, electroneuromyography, positron emission tomography, microneurography, quantitative sensory testing, skin biopsies, nerve conduction and evoked somatosensory potential studies are possible. Pain, being a subjective sensory process, has a wide spectrum of clinical manifestations. For this reason, it is possible to make use of techniques such as screening methods and complementary exams for a more specific diagnosis.
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Humanos , Corteza Somatosensorial , Enfermedades del Sistema Nervioso Central/diagnóstico por imagen , Dolor Crónico/diagnóstico , Sistema Nervioso/fisiopatología , Sistema Nervioso Parasimpático , Sistema Nervioso Central , Triaje , Neuroimagen/métodos , Estudios de Conducción NerviosaRESUMEN
Nitrergic neurons (NNs) are inhibitory neurons capable of releasing nitric oxide (NO) that are labeled with nicotinamide adenine dinucleotide phosphate diaphorase histochemistry. The rat primary somatosensory (S1) and motor (M1) cortices are a favorable model to investigate NN populations by comparing their morphology, since these areas share the border of forepaw representation. The distribution of the Type I NN of the forepaw representation in the S1 and M1 cortices of the rat in different laminar compartments and the morphological parameters related to the cell body and dendritic arborization were measured and compared. We observed that the neuronal density in the S1 (130 NN/mm3 ) was higher than the neuronal density in the M1 (119 NN/mm3 ). Most NN neurons were multipolar (S1 with 58%; M1 with 69%), and a minority of the NN neurons were horizontal (S1 with 6%; M1 with 12%). NN found in S1 had a higher verticality index than NN found in M1, and no significant differences were observed for the other morphological parameters. We also demonstrated significant differences in most of the morphological parameters of the NN between different cortical compartments of S1 and M1. Our results indicate that the NN of the forepaw in S1 and M1 corresponds to a neuronal population, where the functionality is independent of the different types of sensory and motor processing. However, the morphological differences found between the cortical compartments of S1 and M1, as well as the higher density of NNs found in S1, indicate that the release of NO varies between the areas.
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Miembro Anterior/metabolismo , Corteza Motora/metabolismo , Neuronas Nitrérgicas/metabolismo , Corteza Somatosensorial/metabolismo , Animales , Miembro Anterior/química , Miembro Anterior/inervación , Masculino , Corteza Motora/química , Corteza Motora/citología , NADP/análisis , NADP/metabolismo , Neuronas Nitrérgicas/química , Ratas , Ratas Wistar , Corteza Somatosensorial/química , Corteza Somatosensorial/citologíaRESUMEN
A crucial role of cortical networks is the conversion of sensory inputs into perception. In the cortical somatosensory network, neurons of the primary somatosensory cortex (S1) show invariant sensory responses, while frontal lobe neuronal activity correlates with the animal's perceptual behavior. Here, we report that in the secondary somatosensory cortex (S2), neurons with invariant sensory responses coexist with neurons whose responses correlate with perceptual behavior. Importantly, the vast majority of the neurons fall along a continuum of combined sensory and categorical dynamics. Furthermore, during a non-demanding control task, the sensory responses remain unaltered while the sensory information exhibits an increase. However, perceptual responses and the associated categorical information decrease, implicating a task context-dependent processing mechanism. Conclusively, S2 neurons exhibit intriguing dynamics that are intermediate between those of S1 and frontal lobe. Our results contribute relevant evidence about the role that S2 plays in the conversion of touch into perception.
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Macaca mulatta/fisiología , Neuronas/fisiología , Células Receptoras Sensoriales/fisiología , Corteza Somatosensorial/fisiología , Percepción del Tacto/fisiología , Algoritmos , Animales , Lóbulo Frontal/citología , Lóbulo Frontal/fisiología , Modelos Neurológicos , Estimulación Física/métodos , Corteza Somatosensorial/citologíaRESUMEN
We report a patient with reflex tooth-brushing-triggered epilepsy, associated with a post-central lesion within the right somatosensory face area. Contralateral facial sensory and motor phenomena, associated with contralateral upper limb extension, were present at seizure onset after gingival stimulation, but seizures could also be induced by contact with solid food or liquids. Spontaneous seizures also were recorded. Secondary generalization was infrequent. Stereoelectroencephalography implantation was performed, with seizure recording and cortical/subcortical stimulation for mapping, to identify the precise extent of surgical resection. Complete postoperative control of epilepsy was achieved, accompanied by a mild and transient neurological deficit. [Published with video sequence].
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Epilepsia Refleja/diagnóstico , Epilepsia Refleja/cirugía , Corteza Somatosensorial , Adulto , Electrocorticografía , Femenino , Encía/fisiopatología , Humanos , Corteza Somatosensorial/patología , Corteza Somatosensorial/fisiopatología , Corteza Somatosensorial/cirugía , Técnicas EstereotáxicasRESUMEN
Our choices are often informed by temporally integrating streams of sensory information. This has been well demonstrated in the visual and auditory domains, but the integration of tactile information over time has been less studied. We designed an active touch task in which participants explored a spheroid-shaped object to determine its inclination with respect to the horizontal plane (inclined to the left or the right). In agreement with previous findings, our results show that more errors, and longer decision times, accompany difficult decisions (small inclination angles). To gain insight into the decision-making process, we used a time-controlled task in which the experimenter manipulated the time available for tactile exploration on a trial-by-trial basis. The behavioral results were fit with a bounded accumulation model and an independent sampling model that assumes no sensory accumulation. The results of model fits favor an accumulation-to-bound mechanism and suggest that participants integrate the first 600â¯ms of 1800â¯ms-long stimuli. This means that the somatosensory system benefits from longer streams of information, although it does not make use of all available evidence.
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Percepción del Tacto , Tacto , Humanos , Corteza SomatosensorialRESUMEN
A previously introduced Bayesian non-parametric multi-scale technique, called iterated Multigrid Priors (iMGP) method, is used to map the topographic organization of human primary somatosensory cortex (S1). We analyze high spatial resolution fMRI data acquired at ultra-high field (UHF, 7T) in individual subjects during vibrotactile stimulation applied to each distal phalange of the left hand digits using both a travelling-wave (TW) and event-related (ER) paradigm design. We compare the somatotopic digit representations generated in S1 using the iMGP method with those obtained using established fMRI paradigms and analysis techniques: Fourier-based analysis of travelling-wave data and General Linear Model (GLM) analysis of event-related data. Maps derived with the iMGP method are similar to those derived with the standard analysis, but in contrast to the Fourier-based analysis, the iMGP method reveals overlap of activity from adjacent digit representations in S1. These findings validate the use of the iMGP method as an alternative to study digit representations in S1, particularly with the TW design as an attractive means to study cortical reorganization in patient populations such dystonia and carpal tunnel syndrome, where the degree of spatial overlap of cortical finger representations is of interest.
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Imagen por Resonancia Magnética/métodos , Corteza Somatosensorial/fisiología , Adulto , Teorema de Bayes , Mapeo Encefálico/métodos , Femenino , Dedos/fisiología , Análisis de Fourier , Humanos , Modelos Lineales , MasculinoRESUMEN
Busulfan is a bifunctional alkylating agent used for myeloablative conditioning and in the treatment of chronic myeloid leukemia due to its ability to cause DNA damage. However, in rodent experiments, busulfan presented a potential teratogenic and cytotoxic effect. Studies have evaluated the effects of busulfan on fetuses after administration in pregnancy or directly on pups during the lactation period. There are no studies on the effects of busulfan administration during pregnancy on offspring development after birth. We investigated the effects of busulfan on somatic and reflex development and encephalic morphology in young rats after exposure in pregnancy. The pregnant rats were exposed to busulfan (10 mg/kg, intraperitoneal) during the early developmental stage (days 12-14 of the gestational period). After birth, we evaluated the somatic growth, maturation of physical features and reflex-ontogeny during the lactation period. We also assessed the effects of busulfan on encephalic weight and cortical morphometry at 28 days of postnatal life. As a result, busulfan-induced pathological changes included: microcephaly, evaluated by the reduction of cranial axes, delay in reflex maturation and physical features, as well as a decrease in the morphometric parameters of somatosensory and motor cortex. Thus, these results suggest that the administration of a DNA alkylating agent, such as busulfan, during the gestational period can cause damage to the central nervous system in the pups throughout their postnatal development.
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Alquilantes/farmacología , Peso Corporal/efectos de los fármacos , Busulfano/farmacología , Neuronas/efectos de los fármacos , Corteza Somatosensorial/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Recuento de Células , Femenino , Exposición Materna , Embarazo , Efectos Tardíos de la Exposición Prenatal , Ratas , Reflejo/efectos de los fármacosRESUMEN
The paradoxical absence of a split-brain syndrome in most cases of callosal dysgenesis has originated three main hypotheses, namely, (i) bilateral cortical representation of language, (ii) bilateral thalamocortical projections of somatosensory pathways conveyed by the spinothalamic-medial lemniscus system, and (iii) a variable combination of (i) and (ii). We used functional neuroimaging to investigate the cortical representation and lateralization of somatosensory information from the palm of each hand in six cases of callosal dysgenesis (hypothesis [ii]). Cortical regions of interest were contralateral and ipsilateral S1 (areas 3a and 3b, 1 and 2 in the central sulcus and postcentral gyrus) and S2 (parts of areas 40 and 43 in the parietal operculum). The degree of cortical asymmetry was expressed by a laterality index (LI), which may assume values from -1 (fully left-lateralized) to +1 (fully right-lateralized). In callosal dysgenesis, LI values for the right and the left hands were, respectively, -1 andâ¯+â¯1 for both S1 and S2, indicating absence of engagement of ipsilateral S1 and S2. In controls, LI values wereâ¯-â¯0.70 (S1) andâ¯-â¯0.51 (S2) for right hand stimulation, and 0.82 (S1) and 0.36 (S2) for left hand stimulation, reflecting bilateral asymmetric activations, which were significantly higher in the hemisphere contralateral to the stimulated hand. Therefore, none of the main hypotheses so far entertained to account for the callosal dysgenesis-split-brain paradox have succeeded. We conclude that the preserved interhemispheric transfer of somatosensory tactile information in callosal dysgenesis must be mediated by a fourth alternative, such as aberrant interhemispheric bundles, reorganization of subcortical commissures, or both.
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Agenesia del Cuerpo Calloso/fisiopatología , Corteza Somatosensorial/fisiopatología , Percepción del Tacto/fisiología , Adolescente , Adulto , Mapeo Encefálico , Femenino , Lateralidad Funcional , Humanos , Imagen por Resonancia Magnética , Masculino , Estimulación Física , Adulto JovenRESUMEN
OBJECTIVE: The current study aimed to assess the effects of five cycles of automated mechanical somatosensory stimulation (AMSS) of the fore-feet on blood pressure (BP) and cardiovascular autonomic control in Parkinson's Disease patients. METHODS: Out of 23 patients, 16 underwent an AMSS session every 72âh, for a total of five sessions per patient. Electrocardiogram, noninvasive beat-to-beat blood pressure and respiratory activity were recorded for 20âmin in supine position at baseline and after the AMSS sessions. Main outcomes were the changes in SBP and DBP, in the spectral indices of cardiac sympathetic (LFRRn.u.) and vagal (HFRR) modulatory activities, cardiac sympathovagal relationship (LF/HF), vascular sympathetic modulation (LFSAP) and arterial baroreflex sensitivity (sequence technique). Symbolic analysis of heart rate variability provided additional indices of cardiac sympathetic (0V%) and vagal (2UV%) modulation to the sinoatrial node. RESULTS: After five AMSS trials a reduction in SBP (baseline: 131.2â±â15.5âmmHg; post-AMSS: 122.4â±â16.2âmmHg; Pâ=â0.0004) and DBP (baseline: 73.2â±â6.1âmmHg; post-AMSS: 68.9â±â6.2âmmHg; Pâ=â0.008) was observed. Post-AMSS, spectral and symbolic indices of cardiovascular sympathetic control decreased and arterial baroreflex sensitivity increased (baseline: 5.7â±â1.3âms/mmHg; post-AMSS: 11.27â±â2.7âms/mmHg). CONCLUSION: AMSS sessions were effective in reducing BP, increasing baroreflex sensitivity and decreasing cardiovascular sympathetic modulation in Parkinson's disease patients. AMSS might be useful to control supine hypertension in Parkinson's disease.
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Barorreflejo/fisiología , Presión Sanguínea/fisiología , Hipertensión/terapia , Enfermedad de Parkinson/fisiopatología , Estimulación Física , Anciano , Sistema Nervioso Autónomo/fisiopatología , Determinación de la Presión Sanguínea , Sistema Cardiovascular/inervación , Sistema Cardiovascular/fisiopatología , Electrocardiografía , Femenino , Antepié Humano , Corazón/fisiopatología , Frecuencia Cardíaca/fisiología , Hemodinámica , Humanos , Hipertensión/complicaciones , Hipertensión/fisiopatología , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/complicaciones , Corteza Somatosensorial/fisiología , Posición Supina/fisiología , Nervio Vago/fisiopatologíaRESUMEN
Since the pioneering work of Penfield and his colleagues in the 1930s, the somatosensory cortex, which is located on the postcentral gyrus, has been known for its central role in processing sensory information from various parts of the body. More recently, a converging body of literature has shown that the somatosensory cortex also plays an important role in each stage of emotional processing, including identification of emotional significance in a stimulus, generation of emotional states, and regulation of emotion. Importantly, studies conducted in individuals suffering from mental disorders associated with abnormal emotional regulation, such as major depression, bipolar disorder, schizophrenia, post-traumatic stress disorder, anxiety and panic disorders, specific phobia, obesity, and obsessive-compulsive disorder, have found structural and functional changes in the somatosensory cortex. Common observations in the somatosensory cortices of individuals with mood disorders include alterations in gray matter volume, cortical thickness, abnormal functional connectivity with other brain regions, and changes in metabolic rates. These findings support the hypothesis that the somatosensory cortex may be a treatment target for certain mental disorders. In this review, we discuss the anatomy, connectivity, and functions of the somatosensory cortex, with a focus on its role in emotional regulation.
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Humanos , Corteza Somatosensorial/anatomía & histología , Corteza Somatosensorial/fisiología , Emociones/fisiología , Trastornos Mentales/fisiopatología , Corteza Somatosensorial/diagnóstico por imagen , Imagen por Resonancia Magnética , Trastornos Mentales/clasificaciónRESUMEN
Sensory information is processed in specific brain regions, and shared between the cerebral hemispheres by axons that cross the midline through the corpus callosum. However, sensory deprivation usually causes sensory losses and/or functional changes. This is the case of people who suffered limb amputation and show changes of body map organization within the somatosensory cortex (S1) of the deafferented cerebral hemisphere (contralateral to the amputated limb), as well as in the afferented hemisphere (ipsilateral to the amputated limb). Although several studies have approached these functional changes, the possible finer morphological alterations, such as those occurring in callosal axons, still remain unknown. The present work combined histochemistry, single-axon tracing and 3D microscopy to analyze the fine morphological changes that occur in callosal axons of the forepaw representation in early amputated rats. We showed that the forepaw representation in S1 was reduced in the deafferented hemisphere and expanded in the afferented side. Accordingly, after amputation, callosal axons originating from the deafferented cortex undergo an expansion of their terminal arbors with increased number of terminal boutons within the homotopic representation at the afferented cerebral hemisphere. Similar microscale structural changes may underpin the macroscale morphological and functional phenomena that characterize limb amputation in humans.
Asunto(s)
Amputación Traumática/fisiopatología , Axones/fisiología , Cuerpo Calloso/fisiopatología , Plasticidad Neuronal , Terminales Presinápticos/fisiología , Corteza Somatosensorial/fisiopatología , Amputación Traumática/patología , Animales , Axones/patología , Cuerpo Calloso/patología , Miembro Anterior/cirugía , Masculino , Técnicas de Trazados de Vías Neuroanatómicas , Terminales Presinápticos/patología , Ratas Wistar , Corteza Somatosensorial/patologíaRESUMEN
Processing of tactile sensory information in rodents is critically dependent on the communication between the primary somatosensory cortex (S1) and higher-order integrative cortical areas. Here, we have simultaneously characterized single-unit activity and local field potential (LFP) dynamics in the S1, primary visual cortex (V1), anterior cingulate cortex (ACC), posterior parietal cortex (PPC), while freely moving rats performed an active tactile discrimination task. Simultaneous single unit recordings from all these cortical regions revealed statistically significant neuronal firing rate modulations during all task phases (anticipatory, discrimination, response, and reward). Meanwhile, phase analysis of pairwise LFP recordings revealed the occurrence of long-range synchronization across the sampled fronto-parieto-occipital cortical areas during tactile sampling. Causal analysis of the same pairwise recorded LFPs demonstrated the occurrence of complex dynamic interactions between cortical areas throughout the fronto-parietal-occipital loop. These interactions changed significantly between cortical regions as a function of frequencies (i.e. beta, theta and gamma) and according to the different phases of the behavioral task. Overall, these findings indicate that active tactile discrimination by rats is characterized by much more widespread and dynamic complex interactions within the fronto-parieto-occipital cortex than previously anticipated.
Asunto(s)
Giro del Cíngulo/metabolismo , Lóbulo Occipital/metabolismo , Animales , Electrofisiología , Giro del Cíngulo/fisiología , Masculino , Análisis Multivariante , Lóbulo Occipital/fisiología , Lóbulo Parietal/metabolismo , Lóbulo Parietal/fisiología , Ratas , Corteza Somatosensorial/metabolismo , Corteza Somatosensorial/fisiología , Corteza Visual/metabolismo , Corteza Visual/fisiologíaRESUMEN
Amputation in adults is associated with an extensive remapping of cortical topography in primary and secondary sensorimotor areas. Here, we used tactile residual limb stimulation and 3T functional magnetic resonance imaging in humans to investigate functional connectivity changes in the sensorimotor network of patients with long-term lower limb traumatic amputations with phantom sensation, but without pain. We found a pronounced reduction of inter-hemispheric functional connectivity between homologous sensorimotor cortical regions in amputees, including the primary (S1) and secondary (S2) somatosensory areas, and primary (M1) and secondary (M2) motor areas. We additionally observed an intra-hemispheric increased functional connectivity between primary and secondary somatosensory regions, and between the primary and premotor areas, contralateral to amputation. These functional connectivity changes in specialized small-scale sensory-motor networks improve our understanding of the functional impact of lower limb amputation in the brain. Our findings in a selective group of patients with phantom limb sensations, but without pain suggest that disinhibition of neural inputs following traumatic limb amputation disrupts sensorimotor topology, unbalancing functional brain network organization. These findings step up the description of brain plasticity related with phantom sensations by showing that pain is not critical for sensorimotor network changes after peripheral injury.