Biology subjects

Stout, J. C.

Publications and source records attributed to Stout, J. C..

3 recordsLinked to original sources

bioRxiv2023

Ageing attenuates exercise-enhanced motor cortical plasticity

Cardiorespiratory exercise is known to modulate motor cortical plasticity in young adults, but the influence of ageing on this relationship is unknown. Here, we compared the effects of a single session of cardiorespiratory exercise on motor cortical plasticity in young and older adults. We acquired measures of cortical excitatory and inhibitory activity of the primary motor cortex using transcranial magnetic stimulation (TMS) from 20 young (M {+/-} s.d. = 25.30 {+/-} 4.00 years) and 20 older (M {+/-} s.d. = 64.10 {+/-} 6.50 years) healthy adults. Single and paired pulse TMS measures were collected before and after a 20-minute bout of high-intensity interval cycling exercise or an equivalent period of rest, and again after intermittent theta burst stimulation (iTBS). In both young and older adults, exercise led to an increase in glutamatergic excitation and a reduction in gamma-aminobutyric acid (GABA) inhibition. However, in contrast to younger adults, older adults showed an attenuated plasticity response to iTBS following exercise. These results demonstrate an age-dependent decline in cortical plasticity and indicate that a preceding bout of high-intensity interval exercise may be less effective for enhancing primary motor cortex plasticity in older adults. Our findings align with the hypothesis that the capacity for cortical plasticity is altered in older age. Key pointsO_LIExercise enhances motor cortical plasticity in young adults, but how ageing influences this effect is unknown. C_LIO_LIHere, we compared primary motor cortical plasticity responses in young and older adults before and after a bout of high-intensity interval exercise, and again after a plasticity-inducing protocol - intermittent theta burst stimulation. C_LIO_LIIn both young and older adults, exercise led to an increase in glutamatergic excitation and a reduction in gamma-aminobutyric acid (GABAergic) inhibition. C_LIO_LIOur key result was that older adults showed an attenuated plasticity response to theta burst stimulation following exercise, relative to younger adults. C_LIO_LIOur findings demonstrate an age-dependent decline in exercise-enhanced cortical plasticity and indicate that a preceding bout of high-intensity interval exercise may be less effective for enhancing primary motor cortex plasticity in older adults. C_LI

neuroscience↗

bioRxiv2018

Invasive aliens threatened with native extinction: examining best practice for species translocations under climate change

AimTranslocation remains a controversial strategy in species conservation. Here, we utilise the unusual scenario of invasive alien species (IAS) threatened with extinction in their native range to address key challenges in deciding whether, where, and when to implement translocation, and how best to approach conservation under seemingly contradictory circumstances.\n\nLocationIberian Peninsula, NW Europe\n\nMethodsRhododendron ponticum ssp. baeticum was selected as a model IAS for case study analysis. We used species distribution models (SDMs) coupled with dynamic simulations of migration to assess: 1. the extinction risk posed to this species in its native Iberian range under climate change; 2. whether SDMs calibrated on the native range (replicating typical translocation planning) could predict invasive capacity in NW Europe; and 3. the extent to which recommended biogeographical constrains on translocations may limit available options. Insights gained on the above were used to build and test a generic decision framework for translocation, based on robust identification of microrefugia.\n\nResultsOur findings suggest a high likelihood of climate-induced extinction for R.p. ssp. baeticum in its native range. Notably, SDMs completely failed to predict invasive capacity in NW Europe. However, application of our framework was successful in identifying sites more proximate to the native range - albeit outside this species current biogeographic region - potentially suited to translocation.\n\nMain conclusionsThe framework here developed can be used to guide translocation of climate-endangered species in a spatially and temporally precise manner. However, we caution that use of SDMs can possess short-comings in failing to capture a full picture of sites suited to translation, and in risk assessment of the capacity of translocated taxa to form invasive species. Strict biogeographic constraints to the selection of translocation sites can evidently help to safeguard against invasions, but may also severely hinder the options available to avert climate-induced extinctions.

ecology↗

bioRxiv2017

Deep Brain Stimulation for Parkinson’s disease changes perception in the Rubber Hand Illusion

Parkinsons disease (PD) alters cortico-basal ganglia-thalamic circuitry and susceptibility to an illusion of bodily awareness, the Rubber Hand Illusion (RHI). Bodily awareness is thought to result from multisensory integration in a predominantly cortical network; the role of subcortical connections is unknown. We studied the effect of modulating cortico-subcortical circuitry on multisensory integration for bodily awareness in PD patients treated with subthalamic nucleus (STN) deep brain stimulation (DBS) using the RHI experiment. Typically, synchronous visuo-tactile cues induce a false perception of touch on the rubber hand as if it were the subjects hand, whereas asynchronous visuo-tactile cues do not. However, we found that in the asynchronous condition, patients in the off-stimulation state did not reject the RHI as strongly as healthy controls; switching on STN-DBS partially normalised their responses. Patients in the off-stimulation state also misjudged the position of their hand, indicating it to be closer to the rubber hand than controls. However, STN-DBS did not affect proprioceptive judgements or subsequent arm movements altered by the perceptual effects of the illusion. Our findings support the idea that the STN and subcortical connections have a key role in multisensory integration for bodily awareness. Decisionmaking in multisensory bodily illusions is discussed.

neuroscience↗