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Visual features of an observed agent do not modulate human brain activity during action observation
Full text linkRecent neuroimaging evidence in macaques has shown that the neural system underlying the observation of hand actions performed by others (i.e., "action observation system") is modulated by whether the observed action is performed by a person in full view or an isolated hand (i.e., type of view manipulation). Although a human homologue of such circuit has been identified, whether in humans the neural processes involved in this capacity are modulated by the type of view remains unknown. Here we used functional magnetic resonance imaging (fMRI) to investigate whether the "action observation system", with specific reference to the ventral premotor cortex, responds differentially depending on type of view. We also tested this manipulation within regions of the human brain showing overlapping activity for both the observation and the execution of action ("mirror" regions). To this end, the same subjects were requested to observe grasping actions performed under the two types of view (observation conditions) or to perform a grasping action (execution condition). Results from whole-brain analyses indicate that overlapping activity for action observation and execution was evident in a broad network of areas including parietal, premotor and temporal cortices. Activity within such network was evident for both the observation of a person in full view or an isolated hand, but it was not modulated by the type of view. Similarly, results from region of interest (ROI) analyses, performed within the ventral premotor cortex, did confirm that this area responded in a similar fashion following the observation of either an isolated hand or an entire model acting. These findings offer novel insights on what the "action observation" and the "mirror" systems visually code and how the processing underlying such coding may vary across species. Further, they support the hypothesis that action goal is amongst the main determinants for the revelation of action observation activity, and to the existence of a broad system involved in the simulation of action
La relazione fra tipo di prensione e dimensione dello stimolo: uno studio fMRI. Congresso nazionale dell'Associazione Italiana di Psicologia - Sezione sperimentale
No full text
Visual features of an observed agent do not modulate human brain activity during action observation
No full textRecent neuroimaging evidence in macaques has shown that the neural system
underlying the observation of hand actions performed by others (i.e., "action
observation system") is modulated by whether the observed action is performed by
a person in full view or an isolated hand (i.e., type of view manipulation).
Although a human homologue of such circuit has been identified, whether in humans
the neural processes involved in this capacity are modulated by the type of view
remains unknown. Here we used functional magnetic resonance imaging (fMRI) to
investigate whether the "action observation system", with specific reference to
the ventral premotor cortex, responds differentially depending on type of view.
We also tested this manipulation within regions of the human brain showing
overlapping activity for both the observation and the execution of action
("mirror" regions). To this end, the same subjects were requested to observe
grasping actions performed under the two types of view (observation conditions)
or to perform a grasping action (execution condition). Results from whole-brain
analyses indicate that overlapping activity for action observation and execution
was evident in a broad network of areas including parietal, premotor and temporal
cortices. Activity within such network was evident for both the observation of a
person in full view or an isolated hand, but it was not modulated by the type of
view. Similarly, results from region of interest (ROI) analyses, performed within
the ventral premotor cortex, did confirm that this area responded in a similar
fashion following the observation of either an isolated hand or an entire model
acting. These findings offer novel insights on what the "action observation" and
the "mirror" systems visually code and how the processing underlying such coding
may vary across species. Further, they support the hypothesis that action goal is
amongst the main determinants for the revelation of action observation activity,
and to the existence of a broad system involved in the simulation of action
Cortical activations in humans grasp-related areas depend on hand used and handedness
Full text linkBackground: In non-human primates grasp-related sensorimotor transformations are accomplished in a circuit involving the
anterior intraparietal sulcus (area AIP) and both the ventral and the dorsal sectors of the premotor cortex (vPMC and dPMC,
respectively). Although a human homologue of such a circuit has been identified whether activity within this circuit varies
depending on handedness has yet to be investigated.
Methodology/Principal Findings: We used functional magnetic resonance imaging (fMRI) to explicitly test how handedness
modulates activity within human grasping-related brain areas. Right- and left-handers subjects were requested to reach
towards and grasp an object with either the right or the left hand using a precision grip while scanned. A kinematic study
was conducted with similar procedures as a behavioral counterpart for the fMRI experiment. Results from a factorial design
revealed significant activity within the right dPMC, the right cerebellum and AIP bilaterally. The pattern of activity within
these areas mirrored the results found for the behavioral study.
Conclusion/Significance: Data are discussed in terms of an handedness-independent role for the right dPMC in monitoring
hand shaping, the need for bilateral AIP activity for the performance of precision grip movements which varies depending
on handedness and the involvement of the cerebellum in terms of its connections with AIP. These results provide the first
compelling evidence of specific grasping related neural activity depending on handedness
Smelling odors, understanding actions
No full textPrevious evidence indicates that we understand others’ actions not only by perceiving their visual features but
also by their sound. This raises the possibility that brain regions responsible for action understanding respond to
cues coming from different sensory modalities. Yet no studies, to date, have examined if this extends to olfaction.
Here we addressed this issue by using functional magnetic resonance imaging. We searched for brain activity
related to the observation of an action executed towards an object that was smelled rather than seen. The results
show that temporal, parietal, and frontal areas were activated when individuals observed a hand grasping a
smelled object. This activity differed from that evoked during the observation of a mimed grasp. Furthermore,
superadditive activity was revealed when the action target-object was both seen and smelled. Together these
findings indicate the influence of olfaction on action understanding and its contribution to multimodal action
representations
Comparing natural and constrained movements: new insights into the visuomotor control of grasping
Full text linkBackground. Neurophysiological studies showed that in macaques, grasp-related sensorimotor transformations are
accomplished in a circuit connecting the anterior intraparietal sulcus (area AIP) with premotor area F5. Single unit recordings
of macaque indicate that activity of neurons in this circuit is not simply linked to any particular object. Instead, responses
correspond to the final hand configuration used to grasp the object. Although a human homologue of such a circuit has been
identified, its role in planning and controlling different grasp configurations has not been decisively shown. We used
functional magnetic resonance imaging to explicitly test whether activity within this network varies depending on the
congruency between the adopted grasp and the grasp called by the stimulus. Methodology/Principal Findings. Subjects
were requested to reach towards and grasp a small or a large stimulus naturally (i.e., precision grip, involving the opposition of
index finger and thumb, for a small size stimulus and a whole hand grasp for a larger stimulus) or with an constrained grasp
(i.e., a precision grip for a large stimulus and a whole hand grasp for a small stimulus). The human anterior intraparietal sulcus
(hAIPS) was more active for precise grasping than for whole hand grasp independently of stimulus size. Conversely, both the
dorsal premotor cortex (dPMC) and the primary motor cortex (M1) were modulated by the relationship between the type of
grasp that was adopted and the size of the stimulus. Conclusions/Significance. The demonstration that activity within the
hAIPS is modulated according to different types of grasp, together with the evidence in humans that the dorsal premotor
cortex is involved in grasp planning and execution offers a substantial contribution to the current debate about the neural
substrates of visuomotor grasp in humans
Object Presence Modulates Activity within the Somatosensory Component of the Action Observation Network
No full textIn the present study, we used functional magnetic resonance imaging to investigate the influence that the presence of an object, intended as the target for an action, might have on the neural circuit underlying the observation of the movement of others (action observation network [AON]). This system entails a simulation process of the observed movement occurring via the recruitment of the motor and somatosensory cortices involved in the execution of such movement. Here, participants were requested to observe grasping actions ending behind a partition knowing in advance whether a target-object would be present (i.e., object-directed action) or absent (i.e., non object-directed action). These “action” conditions were compared with “control” conditions in which a stationary hand was presented either alone or together with the target-object hidden behind the partition. Activation within most regions of the AON was similar for observing partially occluded object-related and non object-related actions. However, within one of the regions belonging to the AON, namely in the somatosensory cortices, blood oxygen level–dependent activity was modulated by the presence of a target-object. We interpreted such modulation as demonstration of the differential involvement of the somatosensory component of the AON for the coding of these 2 types of actions
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