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PubMed1973

Touch epilepsy.

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Adolescent↗
PubMed2005

Age-related changes in pressure pain threshold, grip strength and touch pressure threshold in upper extremities of older adults.

BACKGROUND AND AIMS: Hand function weakens with age in both men and women, especially after the age of 65. As the number of older people increases, more older adults may have sensorimotor impairment, which affects upper extremity (UE) performance and thus independence in the activities of daily life. The purpose of this study was to detect and evaluate the impact of age on pressure pain threshold (PPT), touch/pressure threshold and grip strength in the decades after the age of 60. METHODS: The study was carried out with the participation of older adults living in the Izmir Geriatric Centre. Older adults were subdivided into three age groups and 128 subjects (47 male, 81 female) were selected systematically as one out of every three individuals in each group (group 1: 60 to 69; group 2: 70 to 79; group 3: 80 or over). Touch/pressure threshold test, pressure pain threshold (PPT) test and grip strength measurement were performed on dominant and non-dominant hands. RESULTS: It was found out that touch/pressure thresholds increased with age, but the change was not statistically significant between the three age groups. PPT and grip strength of dominant and non-dominant hands decreased from groups 1 to 3, but analysis indicated that these declines were not statistically significant. CONCLUSIONS: Despite the fact that age-related sensorimotor changes are not statistically significant, a reduction is seen in sensorimotor parameters after the age of 60.

Aged↗
PubMed2003

Visual enhancement of touch in spatial body representation.

Perception of our own bodies is based on integration of visual and tactile inputs, notably by neurons in the brain's parietal lobes. Here we report a behavioural consequence of this integration process. Simply viewing the arm can speed up reactions to an invisible tactile stimulus on the arm. We observed this visual enhancement effect only when a tactile task required spatial computation within a topographic map of the body surface and the judgements made were close to the limits of performance. This effect of viewing the body surface was absent or reversed in tasks that either did not require a spatial computation or in which judgements were well above performance limits. We consider possible mechanisms by which vision may influence tactile processing.

Adult↗
PubMed2005

Spatiotemporal interactions between audition and touch depend on hand posture.

We report two experiments designed to assess the consequences of posture change on audiotactile spatiotemporal interactions. In Experiment 1, participants had to discriminate the direction of an auditory stream (consisting of the sequential presentation of two tones from different spatial positions) while attempting to ignore a task-irrelevant tactile stream (consisting of the sequential presentation of two vibrations, one to each of the participant's hands). The tactile stream presented to the participants' hands was either spatiotemporally congruent or incongruent with respect to the sounds. A significant decrease in performance in incongruent trials compared with congruent trials was demonstrated when the participants adopted an uncrossed-hands posture but not when their hands were crossed over the midline. In Experiment 2, we investigated the ability of participants to discriminate the direction of two sequentially presented tactile stimuli (one presented to each hand) as a function of the presence of congruent vs incongruent auditory distractors. Here, the crossmodal effect was stronger in the crossed-hands posture than in the uncrossed-hands posture. These results demonstrate the reciprocal nature of audiotactile interactions in spatiotemporal processing, and highlight the important role played by body posture in modulating such crossmodal interactions.

Acoustic Stimulation↗
PubMed2000

Inhibition of return is supramodal: a demonstration between all possible pairings of vision, touch, and audition.

Inhibition of return' (IOR) refers to the delayed detection often found for targets at the same location as a preceding event. We examined whether IOR reflects a truly supramodal phenomenon, in an experiment designed to avoid criticisms of previous crossmodal research. We presented a random sequence of visual, tactile, and auditory targets to either the left or right of central fixation, and tested for IOR between targets in all three modalities when presented successively to the same versus different side. Speeded detection for targets in all three modalities was indeed slower if the preceding target had been presented from the same position, regardless of the modality, of this preceding target. These results demonstrate for the first time that IOR is truly supramodal.

Acoustic Stimulation↗
PubMed2004

Arthropod touch reception: structure and mechanics of the basal part of a spider tactile hair.

Our previous studies on spider tactile hairs concentrated on the mechanical behavior of the hair shaft and the electrophysiological properties of the sensory cells. Here we focus on the structure and mechanical properties of the coupling of the hair shaft and the sensory terminals. 1. The functional "design" of the coupling provides for a combination of high sensitivity and protection against mechanical damage and overstimulation. The dendritic sheath is not directly coupled to the hair shaft. Rather, there is "terminal connecting material" between the dendrites and the hair shaft. 2. The hair shaft forms a first-order lever. Its acentric axis of rotation is located ca.3.5 microm from its inner end. Displacement of the hair tip is scaled down by a factor of ca.750:1, not even considering the outer hair shaft's bending. 3. At threshold the dendrite sheath displacement is ca. 0.05 microm by forces in the order of 0.4-4x10(-6) N. 4. The hair shaft bends within the socket even before contacting it. The elasticities representing its suspension and bending in the socket can be described quantitatively by measuring the hair's restoring moments (range: 10(-9) Nm) and bending at different degrees of deflection.

Animals↗
PubMedDate not supplied

Computational model of touch sensory cells (T Cells) of the leech: role of the afterhyperpolarization (AHP) in activity-dependent conduction failure.

Bursts of spikes in T cells produce an AHP, which results from activation of a Na+/K+ pump and a Ca2+-dependent K+ current. Activity-dependent increases in the AHP are believed to induce conduction block of spikes in several regions of the neuron, which in turn, may decrease presynaptic invasion of spikes and thereby decrease transmitter release. To explore this possibility, we used the neurosimulator SNNAP to develop a multi-compartmental model of the T cell. The model incorporated empirical data that describe the geometry of the cell and activity-dependent changes of the AHP. Simulations indicated that at some branching points, activity-dependent increases of the AHP reduced the number of spikes transmitted from the minor receptive fields to the soma and beyond. More importantly, simulations also suggest that the AHP could modulate, under some circumstances, transmission from the soma to the synaptic terminals, suggesting that the AHP can regulate spike conduction within the presynaptic arborizations of the cell and could in principle contribute to the synaptic depression that is correlated with increases in the AHP.

Action Potentials↗
PubMed2006

Presence: the touch of the puppet.

Using the ideal of the puppet as model and foil, this article looks at ideas about presence, play, animation, and belief. Puppetry's role as a vital, theatrical form has deep roots in universal, cultural experience, and the notion of an inhering spirit that acts for and through image, idol, toy, or fetish is perhaps the central thread running through all attempts to represent and simulate animate life. Through a discussion of the phenomenology of the puppet--the source of its sensory, aesthetic, and metaphysical power--questions are raised about the projection of desire and purpose onto other transitional things, real and imagined.

Consciousness↗
PubMed1986

Reduced responsiveness of touch (SA I) receptors in the cat following close arterial infusion of neomycin.

Electrophysiological recordings were made from afferent nerve fibres supplying slowly adapting type I (SA I) cutaneous mechano-receptors in the cat during application of mechanical stimuli (20 mN constant force, 0.2 s rise time and 2 s plateau phase, every 30 s). Close arterial infusion of neomycin (2.5 mg/min for 5 min) strongly depressed the responsiveness of SA I receptors. A direct effect on the receptor is thought to be the mode of action.

Animals↗
PubMed1993

Modality-specific and amodal aspects of object perception in infancy: the case of active touch.

Three experiments investigated 4.5-month-old infants' perception of the unity and boundaries of haptically presented objects. When infants actively explored the two handles of an unseen object assembly, perception of the unity of the assembly depended on the handles' motion. Infants perceived a single, connected object if the handles moved rigidly together, and they perceived two distinct objects if the handles underwent relative vertical or horizontal motion. When infants passively explored the same object assembly undergoing the same motions, object perception appeared to be indeterminate. The findings of the active motion experiments accord with the findings of studies of visual object perception and suggest that object perception depends on amodal processes, operating on representations of either seen or felt surface motions. The findings of the passive motion experiments nevertheless suggest a difference between visual and haptic perception: for infants as for adults, haptic perception is enhanced by the active production of surface motion.

Adolescent↗