Functional Magnetic Resonance Imaging of the Human Motor Cortex
Alexa Riehle, Eilon Vaadia in Motor Cortex in Voluntary Movements, 2004
Power grip as studied in most of the previously mentioned studies on force- related effects is distinct from precision grip. Ehrsson et al.97 illustrated the corresponding neural difference that manifests in the associated cerebral activation patterns. Precision as opposed to power grip involved less activity in the primary motor cortex, but stronger bilateral activations in the ipsilateral ventral premotor areas, the rostral cingulate motor area, and at several locations in the posterior parietal and prefrontal cortices. In subsequent studies, the same group showed that, in contrast to the behavior during the power grip, the activity in the contralateral primary sensorimotor cortex, as well as in the inferior parietal, ventral premotor, supplementary, and cingulate motor areas, increased when the force of the precision grip was lowered such that it became barely sufficient to hold a given object without letting it slip.98,99 Another interesting recent observation from low force pinch grip is that while the contralateral side shows a weak activation response, the fMRI signal in the ipsilateral M1 decreases. This parallels the ipsilateral reduction of cortical excitability, shown by studies with transcranial magnetic stimulation.100
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The hand posture used to hold a particular object. The two principle categories of grip are precision and power. A typical precision grip in PRIMATES is used when an object is held in opposition between the index finger and thumb. Precision grip alone allows for movement of a small object relative to the different parts of the hand. In a power grip, all of the fingers and the thumb are used in opposition to the palmar surface of the hand. This type of grip is extremely stable and plays an important role in activities such as nonhuman primate locomotion. Grip scaling is the process whereby the hand is opened to a degree appropriate to the size of the target.
Introduction
J. Terrence Jose Jerome in Clinical Examination of the Hand, 2022
We know well that grip is the motor component of prehension. This can be divided into a power grip and a precision grip. They are self-explanatory (Figure 1.33).Power grip: Let us see the example of an orthopaedic surgeon holding the chisel and hammering it as an innate of his operative skills.Precision grip: Let us see the precision work again in the picture. This time the surgeon is focused extensively to achieve accuracy.
Effect of hand postures and object properties on forearm muscle activities using surface electromyography
Published in International Journal of Occupational Safety and Ergonomics, 2020
Kyung-Sun Lee, Myung-Chul Jung
Berguer et al. [10] compared the responses of the forearm and thumb muscles during finger grasping and palm grasping of laparoscopic instruments. They reported that the activities of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) muscles were higher with the palm grasp than with the finger grasp. In addition, Chao et al. [11] concluded that the physical load on the hand could be up to five times greater for a pinch grip than for a power grip. Finneran and O'Sullivan [5] studied the effects of the grip type on the forearm muscle activities. They observed that the forearm muscle activities indicated different maximum voluntary exertions for three different grip types: the power grip, the middle chuck pinch and the right pinch grip. The grip type affects the endurance time and precision of the performance. As the grip type becomes more precise, the grip strength decreases [12]. The power grip, which uses the intrinsic and large muscle groups of the hand, should be used for power activities [13]. Previous studies showed that hand postures are a very important factor when holding objects, along with the effect that the hand posture has on the muscle activities. In this respect, Moore and Dalley [14] reported that a precision grip involves changing the position of the handled object, where the hand and wrist are held firm by the long flexor and extensor muscles, and the intrinsic muscles of the hand perform the fine movements of the fingers.
Effect of object substitution, spontaneous compensation and repetitive training on reaching movements in a patient with optic ataxia
Published in Neuropsychological Rehabilitation, 2020
Josselin Baumard, Frédérique Etcharry-Bouyx, Valérie Chauviré, Delphine Boussard, Mathieu Lesourd, Chrystelle Remigereau, Yves Rossetti, François Osiurak, Didier Le Gall
Grasping corresponds to the shaping of the hand while taking an object (e.g., a paper clip calls for a precision grip whereas a pencil holder calls for a power grip; e.g., Bongers, Zaal, & Jeannerod, 2012; Castiello, 2005; Jeannerod, 1986). Graspable tools (in comparison with non-graspable tools) automatically attract visual attention (e.g., cup versus cactus; Garrido-Vásquez & Schubö, 2014) and elicit activity in the left premotor and parietal cortex (Grafton, Fadiga, Arbib, & Rizzolatti, 1997). That being said, the grasping component is in an intermediate position between reaching and using in that it can be viewed as a high-level perceptual-motor skill (Rosenbaum, Chapman, Weigelt, Weiss, & Van der Wel, 2012). Indeed, grasping may depend not only on structural information (i.e., the shape or size of the object; Ellis & Tucker, 2000) but also on functional information (i.e., knowledge about the function and the prototypical manipulation of an object; Buxbaum, Kyle, Tang, & Detre, 2006; Jax, Buxbaum, & Moll, 2006) and intentional/teleological information (i.e., the action to be done with the object; Osiurak et al., 2008; Rosenbaum et al., 2012). Function-based grasping may depend on the left inferior parietal lobe whereas structure-based grasping is associated with the left superior parietal lobe (Buxbaum, Sirigu, Schwartz, & Klatzky, 2003).
Typical Development of Finger Position Sense From Late Childhood to Adolescence
Published in Journal of Motor Behavior, 2023
Jinseok Oh, Arash Mahnan, Jiapeng Xu, Hannah J. Block, Jürgen Konczak
A different limitation of the current test is that it only examines finger position with respect to the abduction/adduction of the finger and not for finger flexion/extension – a degree of freedom with a larger range of motion. There is evidence that different degrees-of-freedom (DoF) of a joint exhibit difference in proprioceptive acuity or sensitivity. For example, wrist position sense acuity is anisotropic with the abduction/adduction DoF having a higher acuity than flexion/extension (Marini et al., 2016). Such higher acuity is associated with a higher mechanoreceptor density in abductor/adductor muscle and is thought to reflect differences in function and required feedback resolution (Hagert et al., 2005). It is known that finger flexion/extension is critical for grasping while abduction/adduction movements are crucial for fine motor skills such as the precision grip (e.g. pinching between the thumb and index finger). Thus, these differences in function may be also associated with differences in proprioceptive acuity.