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Shadows in the mirror
No full textMirror neurons are a class of visuo-motor neurons activated by both the execution and passive observation of object-related actions. Evidence for the existence of mirror neurons in the human brain comes in part from transcranial magnetic stimulation studies showing that observation of an action causes subliminal activation of corresponding corticospinal pathways within the motor system. During daylight and lighted conditions movement is nearly always preceded, accompanied, and followed by shadows. Shadows that are cast as someone observes a biological movement could potentially provide information for action recognition. The objective of this study was to assess the mirror system's ability to resonate with shadowed movements. Primary motor cortex excitability was evaluated here by motor-evoked potentials elicited during single-pulse transcranial magnetic stimulation and recorded from two hand muscles as participants observed a prehensile action performed in two illumination conditions: one in which the observed action was fully illuminated and one in which a moving body part was partially shadowed. It will be shown that overall modulation of the primary motor cortex excitability during action observation is significantly lower for the shadowed with respect to the fully illuminated condition. Processing shadows determines a modulation of corticospinal excitability, suggesting that the mirror system is finely tuned to that visual aspect of biological movements. NeuroReport 24:63-67 (C) 2013 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins. NeuroReport 2013, 24:63-6
Olfactory influences on reach-to-press movements in a stop-signal task
Full text linkResponse inhibition is sensitive to unexpected changes in the environment triggered by emotional stimuli. Whereas the impact of visual material on inhibition has been widely documented, the attention on the influence of olfactory stimuli has been neglected. Here, we examined the effect of pleasant (orange), unpleasant (trimethyloxazole), and control (clean air) odour primes in a stop-signal task. Twenty-five participants had to elicit or inhibit reach-to-press actions which allowed to examine the olfactory influences on both the planning (release phase) and the on-line control (reaching phase) of responses. Additionally, we manipulated the distance between the initial hand position and the target to be pressed (10 vs. 20 vs. 30 cm). The pleasant (vs. control) odour impaired inhibition, as reflected in slower stop-signal reaction times and higher release errors, indicating greater mobilisation of inhibitory resources by pleasant stimuli. Further, faster release responses were triggered by pleasant and unpleasant primes, supporting the idea of perceptual prioritisation of emotional (vs. non-emotional) stimuli. The olfactory manipulation did not affect the reaching phase of the responses. Instead, the distance manipulation modulated the reaching but not the release phase. These results extend the sparse literature on the influences of odour stimuli on response inhibition
Le piante. Vita intelligente dei nostri paesaggi
Full text linkIn this essay we will delve into the behavior of plants, one of the main elements that characterize our landscapes. A solid understanding of a landscape cannot exclude a deep knowledge of the plants world and the dynamics that exist between the communities of plants that compose it. The aim is to go beyond the vision of greenery as a mere background and compositional language to consider it, more properly, as the main actor of the landscape, with its needs, its peculiarities and its...intelli-gence. We will initially make a brief excursus into the remarkable cognitive capacities of plants, and then we will focus on the complex interactions that plants are capable of in order to enhance their survival. We will conclude emphasizing the value of green spaces also for the protection of biodiversity and ecosystems
Distractor objects affect fingers' angular distances but not fingers' shaping during grasping
No full textThe aim of the present study was to determine whether and how hand shaping was
affected by the presence of a distractor object adjacent to the to-be-grasped
object. Twenty subjects were requested to reach towards and grasp a 'convex' or a
'concave' object in the presence or absence of a distractor object either of the
same or different shape than the target object. Flexion/extension at the
metacarpal-phalangeal (MCP) and proximal interphalangeal joints of all digits,
and abduction angle between digits were measured by resistive sensors embedded in
a glove. The results indicate robust interference effects at the level of reach
duration and the extent of fingers' abduction angles together with changes at the
level of a single joint for the thumb. No distractor effects on individual
fingers' joints except for the MCP of the middle and little fingers were found.
These findings suggest that the presence of distractor object affects hand
shaping in terms of fingers' abduction angles, but not at the level of 'shape
dependent' fingers' angular excursions. Furthermore, they support the importance
of the thumb for the guidance of selective reach-to-grasp movements. We discuss
these results in the context of current theories proposed to explain the object
selection processes underlying the control of hand action
An object for an action, the same object for other actions: Effects on hand shaping
No full textObjects can be grasped in several ways due to their physical properties, the
context surrounding the object, and the goal of the grasping agent. The aim of
the present study was to investigate whether the prior-to-contact grasping
kinematics of the same object vary as a result of different goals of the person
grasping it. Subjects were requested to reach toward and grasp a bottle filled
with water, and then complete one of the following tasks: (1) Grasp it without
performing any subsequent action; (2) Lift and throw it; (3) Pour the water into
a container; (4) Place it accurately on a target area; (5) Pass it to another
person. We measured the angular excursions at both metacarpal-phalangeal (mcp)
and proximal interphalangeal (pip) joints of all digits, and abduction angles of
adjacent digit pairs by means of resistive sensors embedded in a glove. The
results showed that the presence and the nature of the task to be performed
following grasping affect the positioning of the fingers during the reaching
phase. We contend that a one-to-one association between a sensory stimulus and a
motor response does not capture all the aspects involved in grasping. The
theoretical approach within which we frame our discussion considers internal
models of anticipatory control which may provide a suitable explanation of our
results
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