Effects of age and expertise on tactile learning in humans

Abstract

Repetitive tactile stimulation is a well-established tool for inducing somatosensory cortical plasticity and changes in tactile perception. Previous studies have suggested that baseline performance determines the amount of stimulation-induced learning differently in specific populations. Older adults with lower baseline performance than young adults, but also experts, with higher baseline performance than non-experts of the same age, have been found to profit most from such interventions. This begs the question of how age-related and expertise-related differences in tactile learning are reflected in neurophysiological correlates. In two experiments, we investigated how tactile learning depends on age (experiment 1) and expertise (experiment 2). We assessed tactile spatial and temporal discrimination accuracy and event-related potentials (ERPs) in 57 persons of different age and expertise groups before and after a 30-min tactile stimulation intervention. The intervention increased accuracy in temporal (found in experiment 1) and spatial (found in experiment 2) discrimination. Experts improved more than non-experts in spatial discrimination. Lower baseline performance was associated with higher learning gain in experts and non-experts. After the intervention, P300 latencies were reduced in young adults and amplitudes were increased in late middle-aged adults in the temporal discrimination task. Experts showed a steeper P300 parietal-to-frontal gradient after the stimulation. We demonstrated that tactile stimulation partially reverses the age-related decline in late middle-aged adults and increases processing speed in young adults. We further showed that learning gain depends on baseline performance in both non-experts and experts. In experts, however, the upper limit for learning seems to be shifted to a higher level.

Two-Tactor Vibrotactile Navigation Information for the Blind: Directional Resolution and Intuitive Interpretation

“…However, this should not be a prerequisite for directly using the directional information without building a mental representation of space. With respect to the vibrotactile stimulation itself, previous studies have found only minor age effects [27] in 60-years-old participants. With further increases in age, vibration intensity thresholds increase, possibly because pacinian corpuscles are affected [28]- [30].…”

Effects of tDCS on tactile perception in musicians and non-musicians

“…Significant expertise by intervention interaction was found. The learning effect for the group of experts by occupation was found to be stronger than for the novice controls [24]. The above findings suggest that experts are more susceptible to effects of tactile stimulation than novices and raises the question whether tDCS will produce such difference as well.…”

“…Besides described effects of peripheral or brain stimulation on tactile performance, it has been well established that individual tactile sensitivity and perception at all ages strongly depends on accumulating effects of use or disuse [19], [20]. Particularly, extensive daily tactile stimulation as in musicians or blind Braille readers [21]- [23] or in professionals such as surgeons, opticians, or fine mechanics [24], may alter tactile perception and related somatosensory cortical representations. In one study, expertise was defined solely by occupation, where service employees such as office clerks formed the novices group and craftsmen such as goldsmiths, dentists and watch makers formed the experts group.…”

Is plasticity in the human motor cortices altered in healthy older adults?

“…For example, experts with high occupational use of the hands and fingers are found to experience stronger intervention-related improvement than non-experts after training on a tactile discrimination task (Reuter et al, 2014), supporting the idea that activity prior to the testing session influences responses to neuroplasticity inducing interventions. Future studies might try to account for the effects of prior experience and voluntary activity by manipulating the initial activity state of cells and synapses prior to neuroplasticity induction.…”

“…Evidence does demonstrate, however, that metaplasticity may differ as a function of prior experience (Reuter et al, 2014;Rosenkranz et al, 2007). For example, experts with high occupational use of the hands and fingers are found to experience stronger intervention-related improvement than non-experts after training on a tactile discrimination task (Reuter et al, 2014), supporting the idea that activity prior to the testing session influences responses to neuroplasticity inducing interventions.…”