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- Birznieks, Ingvars, et al.
(author)
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Slowly adapting mechanoreceptors in the borders of the human fingernail encode fingertip forces
- 2009
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In: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 29:29, s. 9370-9379
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Journal article (peer-reviewed)abstract
- There are clusters of slowly adapting (SA) mechanoreceptors in the skin folds bordering the nail. These "SA-IInail" afferents, which constitute nearly one fifth of the tactile afferents innervating the fingertip, possess the general discharge characteristics of slowly adapting type II (SA-II) tactile afferents located elsewhere in the glabrous skin of the human hand. Little is known about the signals in the SA-IInail afferents when the fingertips interact with objects. Here we show that SA-IInail afferents reliably respond to fingertip forces comparable to those arising in everyday manipulations. Using a flat stimulus surface, we applied forces to the finger pad while recording impulse activity in 17 SA-IInail afferents. Ramp-and-hold forces (amplitude 4 N, rate 10 N/s) were applied normal to the skin, and at 10, 20, or 30 degrees from the normal in eight radial directions with reference to the primary site of contact (25 force directions in total). All afferents responded to the force stimuli, and the responsiveness of all but one afferents was broadly tuned to a preferred direction of force. The preferred directions among afferents were distributed all around the angular space, suggesting that the population of SA-IInail afferents could encode force direction. We conclude that signals in the population of SA-IInail afferents terminating in the nail walls contain vectorial information about fingertip forces. The particular tactile features of contacted surfaces would less influence force-related signals in SA-IInail afferents than force-related signals present in afferents terminating in the volar skin areas that directly contact objects.
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- Breitholtz, E, et al.
(author)
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Cognitions in generalized anxiety disorder and panic disorder patients
- 1998
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In: Journal of Anxiety Disorders. ; 12, s. 567-577
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Journal article (peer-reviewed)abstract
- Forty-three patients with generalized anxiety disorder (GAD) and 44 patients with panic disorder (PD) were given a standardized interview about thoughts and images during times of anxiety. The two groups differed significantly regarding the ideational con
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- Carlbring, P, et al.
(author)
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Paniksyndromsbehandling via Internet
- 2000
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In: Paper presented at Beteendeterapeutiska Föreningens årsmöte, Uppsala..
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Conference paper (other academic/artistic)
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- Ehrsson, HH, et al.
(author)
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Cortical activity in precision- versus power-grip tasks: an fMRI study
- 2000
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In: Journal of neurophysiology. - : American Physiological Society. - 0022-3077 .- 1522-1598. ; 83:1, s. 528-536
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Journal article (peer-reviewed)abstract
- Most manual grips can be divided in precision and power grips on the basis of phylogenetic and functional considerations. We used functional magnetic resonance imaging to compare human brain activity during force production by the right hand when subjects used a precision grip and a power grip. During the precision-grip task, subjects applied fine grip forces between the tips of the index finger and the thumb. During the power-grip task, subjects squeezed a cylindrical object using all digits in a palmar opposition grasp. The activity recorded in the primary sensory and motor cortex contralateral to the operating hand was higher when the power grip was applied than when subjects applied force with a precision grip. In contrast, the activity in the ipsilateral ventral premotor area, the rostral cingulate motor area, and at several locations in the posterior parietal and prefrontal cortices was stronger while making the precision grip than during the power grip. The power grip was associated predominately with contralateral left-sided activity, whereas the precision-grip task involved extensive activations in both hemispheres. Thus our findings indicate that in addition to the primary motor cortex, premotor and parietal areas are important for control of fingertip forces during precision grip. Moreover, the ipsilateral hemisphere appears to be strongly engaged in the control of precision-grip tasks performed with the right hand.
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