Browsing by Author "Castelo-Branco, Miguel"
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- Bilateral versus ipsilesional cortico-subcortical activity patterns in stroke show hemispheric dependencePublication . Vidal, A. Cristina; Banca, Paula; Pascoal, Augusto G.; Santo, Gustavo C.; Sargento-Freitas, João; Gouveia, Ana; Castelo-Branco, MiguelBackground Understanding of interhemispheric interactions in stroke patients during motor control is an important clinical neuroscience quest that may provide important clues for neurorehabilitation. In stroke patients, bilateral overactivation in both hemispheres has been interpreted as a poor prognostic indicator of functional recovery. In contrast, ipsilesional patterns have been linked with better motor outcomes. Aim We investigated the pathophysiology of hemispheric interactions during limb movement without and with contralateral restraint, to mimic the effects of constraint-induced movement therapy. We used neuroimaging to probe brain activity with such a movement-dependent interhemispheric modulation paradigm. Methods We used an fMRI block design during which the plegic/paretic upper limb was recruited/mobilized to perform unilateral arm elevation, as a function of presence versus absence of contralateral limb restriction ( n = 20, with balanced left/right lesion sites). Results Analysis of 10 right-hemispheric stroke participants yielded bilateral sensorimotor cortex activation in all movement phases in contrast with the unilateral dominance seen in the 10 left-hemispheric stroke participants. Superimposition of contralateral restriction led to a prominent shift from activation to deactivation response patterns, in particular in cortical and basal ganglia motor areas in right-hemispheric stroke. Left-hemispheric stroke was in general characterized by reduced activation patterns, even in the absence of restriction, which induced additional cortical silencing. Conclusion The observed hemispheric-dependent activation/deactivation shifts are novel and these pathophysiological observations suggest short-term neuroplasticity that may be useful for hemisphere-tailored neurorehabilitation.
- Brain Activity during Lower-Limb Movement with Manual Facilitation: An fMRI StudyPublication . Almeida, Patrícia; Vieira, Ana Isabel; Canário, Nádia; Castelo-Branco, Miguel; Castro-Caldas, AlexandreBrain activity knowledge of healthy subjects is an important reference in the context of motor control and reeducation. While the normal brain behavior for upper-limb motor control has been widely explored, the same is not true for lower-limb control. Also the effects that different stimuli can evoke on movement and respective brain activity are important in the context of motor potentialization and reeducation. For a better understanding of these processes, a functional magnetic resonance imaging (fMRI) was used to collect data of 10 healthy subjects performing lower-limb multijoint functional movement under three stimuli: verbal stimulus, manual facilitation, and verbal +manual facilitation. Results showed that, with verbal stimulus, both lower limbs elicit bilateral cortical brain activation; with manual facilitation, only the left lower limb (LLL) elicits bilateral activation while the right lower limb (RLL) elicits contralateral activation; verbal + manual facilitation elicits bilateral activation for the LLL and contralateral activation for the RLL. Manual facilitation also elicits subcortical activation in white matter, the thalamus, pons, and cerebellum. Deactivations were also found for lower-limb movement. Manual facilitation is stimulus capable of generating brain activity in healthy subjects. Stimuli need to be specific for bilateral activation and regarding which brain areas we aim to activate.
- Decoding Musical Valence and Arousal: Exploring the Neural Correlates of Music-Evoked Emotions and the Role of Expressivity FeaturesPublication . Sayal, Alexandre; Guedes, Ana Gabriela; Almeida, Inês A. T.; Jardim Pereira, Daniela; Lima, César F.; Panda, Renato; Paiva, Rui Pedro; Sousa, Teresa; Castelo-Branco, Miguel; Bernardino, Inês; Direito, BrunoMusic conveys both basic emotions, like joy and sadness, and complex ones, such as tenderness and nostalgia. Its effects on emotion regulation and reward have attracted much research attention, as the neural correlates of music-evoked emotions may inform neurorehabilitation interventions. Here, we used fMRI to decode and examine the neural correlates of perceived valence and arousal in music excerpts. Twenty participants were scanned while listening to 96 music excerpts, classified beforehand into four categories varying in valence and arousal. Music modulated activity in cortical regions, most noticeably in music-specific subregions of the auditory cortex, thalamus, and regions of the reward network such as the amygdala. Using multivoxel pattern analysis, we created a computational model to decode the perceived valence and arousal of the music excerpts with above-chance accuracy. We further explored associations between musical features and brain activity in valence-, arousal-, reward-, and auditory-related networks. The results emphasize the involvement of distinct musical features, notably expressive features such as vibrato and tonal and spectral dissonance in valence, arousal, and reward brain networks. Using ecologically valid music stimuli, we contribute to delineating the neural correlates of music-evoked emotions with potential implications in the development of novel music-based neurorehabilitation strategies.
- Unisensory and multisensory Self-referential stimulation of the lower limb: An exploratory fMRI study on healthy subjectsPublication . Vieira, Ana Isabel; Almeida, Patrícia; Canário, Nádia; Castelo-Branco, Miguel; Nunes, Maria Vânia; Castro-Caldas, AlexandreBackground: The holistic view of the person is the essence of the physiotherapy. Knowledge of approaches that develop the whole person promotes better patient outcomes. Multisensory Selfreferential stimulation, more than a unisensory one, seems to produce a holistic experience of the Self (“Core-Self”). Objectives: (1) To analyze the somatotopic brain activation during unisensory and multisensorial Self-referential stimulus; and (2) to understand if the areas activated by multisensorial Self-referential stimulation are the ones responsible for the “Core-Self.” Methods: An exploratory functional magnetic resonance imaging (fMRI) study was performed with 10 healthy subjects, under the stimulation of the lower limbs with three Self-referential stimuli: unisensory auditory-verbal, unisensory tactile-manual, and multisensory, applying the unisensory stimuli simultaneously. Results: Unisensory stimulation elicits bilateral activations of the temporoparietal junction (TPJ), of the primary somatosensory cortex (S1), of the primary motor cortex (BA4), of the premotor cortex (BA6) and of BA44; multisensory stimulation also elicits activity in TPJ, BA4, and BA6, and when compared with unisensory stimuli, activations were found in: (1) Cortical and subcortical midline structures—BA7 (precuneus), BA9 (medial prefrontal cortex), BA30 (posterior cingulated), superior colliculum and posterior cerebellum; and (2) Posterior lateral cortex—TPJ, posterior BA13 (insula), BA19, and BA37. Bilateral TPJ is the one that showed the biggest activation volume. Conclusion: This specific multisensory stimulation produces a brain activation map in regions that are responsible for multisensory Self-processing and may represent the Core- Self. We recommend the use of this specific multisensory stimulation as a physiotherapy intervention strategy that might promote the Self-reorganization.