Conference Paper

fNIRS measure of transitive and intransitive gesture execution, observation and imagination in ecological setting: A pilot study

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Abstract

To explore the presence of differential cortical hemodynamic activations related to cognitive components of actions, we performed a fNIRS (functional Near-Infrared Spectroscopy) study during Observation (O), Execution (E) and Imagination (I) of complex and meaningful (transitive and intransitive) gestures in ecological setting. A pilot sample of 5 healthy adults underwent an event-related study consisting of these 3 different conditions, with O set as first and followed by a randomized presentation of E or I. fNIRS measurements were performed using a 24 channel array of optodes (8 light injectors and 8 detectors) placed over the contralateral central, centro-parietal, parietal and temporal areas. Results showed that the premotor (PMC) and the sensory-motor cortices (SM1) were recruited selectively during E, with levels of oxygenated hemoglobin (oxy-Hb) higher than the other conditions, while the posterior parietal cortex (PPC) showed increased oxy-Hb levels for both E and O. These data suggest that variations in hemodynamic responses can be attributed to different neural processes underpinning these tasks, with PMC and SM1 being more involved in action preparation and performance, and PPC prevalently dedicated to attentive processes related to the execution and observation of limb movements.

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Interactive paradigms inducing reactive aggression are absent in the brain mapping literature. We used a competitive reaction time task to investigate brain regions involved in social interaction and reactive aggression in sixteen healthy male subjects with fMRI. Subjects were provoked by increasingly aversive stimuli and were given the opportunity to respond aggressively against their opponent by administering a stimulus as retaliation. fMRI revealed an increase of medial prefrontal cortex (mPFC) activity during retaliation. The dorsal mPFC was active when subjects had to select the intensity of the retaliation stimulus, and its activity correlated with the selected stimulus strength. In contrast, ventral mPFC was active during observing the opponent suffering but also during retaliation independent of the stimulus strength. Ventral mPFC activation, stronger in low callous subjects, correlated positively with skin conductance response during observation of the suffering opponent. In conclusion, dorsal mPFC activation seems to represent cognitive operations related to more intense social interaction processes whereas the ventral mPFC might be involved in affective processes associated with compassion to the suffering opponent.
Article
Although generally studied in isolation, language and action often co-occur in everyday life. Here we investigated one particular form of simultaneous language and action, namely speech and gestures that speakers use in everyday communication. In a functional magnetic resonance imaging study, we identified the neural networks involved in the integration of semantic information from speech and gestures. Verbal and/or gestural content could be integrated easily or less easily with the content of the preceding part of speech. Premotor areas involved in action observation (Brodmann area [BA] 6) were found to be specifically modulated by action information "mismatching" to a language context. Importantly, an increase in integration load of both verbal and gestural information into prior speech context activated Broca's area and adjacent cortex (BA 45/47). A classical language area, Broca's area, is not only recruited for language-internal processing but also when action observation is integrated with speech. These findings provide direct evidence that action and language processing share a high-level neural integration system.
Article
In this event-related fMRI study, we demonstrate the effects of a single session of practising configural hand actions (guitar chords) on cortical activations during observation, motor preparation and imitative execution. During the observation of non-practised actions, the mirror neuron system (MNS), consisting of inferior parietal and ventral premotor areas, was more strongly activated than for the practised actions. This finding indicates a strong role of the MNS in the early stages of imitation learning. In addition, the left dorsolateral prefrontal cortex (DLPFC) was selectively involved during observation and motor preparation of the non-practised chords. This finding confirms Buccino et al.'s [Buccino, G., Vogt, S., Ritzl, A., Fink, G.R., Zilles, K., Freund, H.-J., Rizzolatti, G., 2004a. Neural circuits underlying imitation learning of hand actions: an event-related fMRI study. Neuron 42, 323-334] model of imitation learning: for actions that are not yet part of the observer's motor repertoire, DLPFC engages in operations of selection and combination of existing, elementary representations in the MNS. The pattern of prefrontal activations further supports Shallice's [Shallice, T., 2004. The fractionation of supervisory control. In: Gazzaniga, M.S. (Ed.), The Cognitive Neurosciences, Third edition. MIT Press, Cambridge, MA, pp. 943-956] proposal of a dominant role of the left DLPFC in modulating lower level systems and of a dominant role of the right DLPFC in monitoring operations.
Article
Near-infrared spectroscopy (NIRS) was used to assess human motor-cortex oxygenation changes in response to self-paced movements as well as movement imagery. We used a 24 channel NIRS-system which allows non-invasive monitoring of cerebral oxygenation changes in the human brain induced by cortical activity. From previous studies it is known that motor imagery activates sensorimotor areas similar to those activated during execution of the same movement. Sixteen healthy subjects were recruited and the changes in concentration of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were examined during a simple right and left hand tapping task and during kinesthetic movement imagery. All subjects showed significant increases in oxy-Hb during both tasks compared to the resting period, but with different onset latencies of oxygenation. During left and right movement imagery, the oxy-Hb concentration increased about 2 s later compared to real movement execution. Furthermore, the oxygenation found was bilaterally represented for both tasks but with temporal differences. The present study reported new results concerning timing and topographical distribution of the hemodynamic response during motor imagery measured by near-infrared spectroscopy.
Article
Determining the brain adaptations that underlie complex tool-use skills is an important component in understanding the physiological bases of human material culture. It is argued here that the ways in which humans skilfully use tools and other manipulable artefacts is possible owing to adaptations that integrate sensory-motor and cognitive processes. Data from brain-injured patients and functional neuroimaging studies suggest that the left cerebral hemisphere, particularly the left parietal cortex, of modern humans is specialized for this purpose. This brain area integrates dynamically representations that are computed in a distributed network of regions, several of which are also left-lateralized. Depending on the nature of the task, these may include conceptual knowledge about objects and their functions, the actor's goals and intentions, and interpretations of task demands. The result is the formation of a praxis representation that is appropriate for the prevailing task context. Recent evidence is presented that this network is organized similarly in the right- and left-handed individuals, and participates in the representation of both familiar tool-use skills and communicative gestures. This shared brain mechanism may reflect common origins of the human specializations for complex tool use and language.
Article
To compare the effects of bilateral task training with unilateral task training on upper-limb outcomes in early poststroke rehabilitation. A single-blinded randomized controlled trial, with outcome assessments at baseline, postintervention (6 wk), and follow-up (18 wk). Inpatient acute and rehabilitation hospitals. Patients were randomized to receive bilateral training (n=56) or unilateral training (n=50) at 2 to 4 weeks poststroke onset. Supervised bilateral or unilateral training for 20 minutes on weekdays over 6 weeks using a standardized program. Upper-limb outcomes were assessed by Action Research Arm Test (ARAT), Rivermead Motor Assessment upper-limb scale, and Nine-Hole Peg Test (9HPT). Secondary measures included the Modified Barthel Index, Hospital Anxiety and Depression Scale, and Nottingham Health Profile. All assessment was conducted by a blinded assessor. No significant differences were found in short-term improvement (0-6 wk) on any measure (P>.05). For overall improvement (0-18 wk), the only significant between-group difference was a change in the 9HPT (95% confidence interval [CI], 0.0-0.1; P=.05) and ARAT pinch section (95% CI, 0.3-5.6; P=.03), which was lower for the bilateral training group. Baseline severity significantly influenced improvement in all upper-limb outcomes (P<.05), but this was irrespective of the treatment group. Bilateral training was no more effective than unilateral training, and in terms of overall improvement in dexterity, the bilateral training group improved significantly less. Intervention timing, task characteristics, dose, and intensity of training may have influenced the results and are therefore areas for future investigation.