Sensorimotor integration refers to the process of combining incoming sensory information with outgoing motor commands to control movement. Short-latency afferent inhibition (SAI), and long-latency ...afferent inhibition (LAI) are neurophysiological measures of sensorimotor integration collected using transcranial magnetic stimulation. No studies to date have investigated the influence of tactile discrimination training on these measures. This study aimed to determine whether SAI and LAI are modulated following training on a custom-designed tactile discrimination maze task. Participants performed a 'high difficulty' and 'low difficulty' maze training condition on separate visits. On an additional visit, no maze training was performed to serve as a control condition. Despite evidence of performance improvements during training, there were no significant changes in SAI or LAI following training in either condition. The total number of errors during maze training was significantly greater in the high-difficulty condition compared with the low-difficulty condition. These findings suggest that sensorimotor maze training for 30 min is insufficient to modify the magnitude of SAI and LAI.
Short‐ and long‐latency afferent inhibition (SAI and LAI respectively) are phenomenon whereby the motor evoked potential induced by transcranial magnetic stimulation (TMS) is inhibited by a sensory ...afferent volley consequent to nerve stimulation. It remains unclear whether dopamine participates in the genesis or modulation of SAI and LAI. The present study aimed to determine if SAI and LAI are modulated by levodopa (l‐DOPA). In this placebo‐controlled, double‐anonymized study Apo‐Levocarb (100 mg l‐DOPA in combination with 25 mg carbidopa) and a placebo were administered to 32 adult males (mean age 24 ± 3 years) in two separate sessions. SAI and LAI were evoked by stimulating the median nerve and delivering single‐pulse TMS over the motor hotspot corresponding to the first dorsal interosseous muscle of the right hand. SAI and LAI were quantified before and 1 h following ingestion of drug or placebo corresponding to the peak plasma concentration of Apo‐Levocarb. The results indicate that Apo‐Levocarb increases SAI and does not significantly alter LAI. These findings support literature demonstrating increased SAI following exogenous dopamine administration in neurodegenerative disorders.
Key points
Short‐ and long‐latency afferent inhibition (SAI and LAI respectively) are measures of corticospinal excitability evoked using transcranial magnetic stimulation.
SAI and LAI are reduced in conditions such as Parkinson's disease which suggests dopamine may be involved in the mechanism of afferent inhibition.
125 mg of Apo‐Levocarb (100 mg dopamine) increases SAI but not LAI.
This study increases our understanding of the pharmacological mechanism of SAI and LAI.
figure legend Short‐ and long‐latency afferent inhibition are evoked by pairing single‐pulse transcranial magnetic stimulation (TMS) with peripheral nerve stimulation. Participants received levodopa (l‐DOPA) and Placebo on separate sessions. SAI was increased in the presence of L‐DOPA but not Placebo.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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Intersession reliability of fast motor mapping using TMS Adams, Faith C.; Foglia, Stevie D.; Drapeau, Chloe C. ...
Brain stimulation,
November-December 2023, 2023 Nov-Dec, 2023-11-00, 20231101, 2023-11-01, Volume:
16, Issue:
6
Journal Article
Peer reviewed
Open access
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•As few as 20 trials of data lead to high intrasession relative reliability for afferent inhibition.•Afferent inhibition is a good indicator of group level, but not individual change in a ...within-session model.•Whenever possible, studies should attempt to include assessments of reliability to verify their findings.
To establish the intrasession relative and absolute reliability of Short (SAI) and Long-Latency Afferent Inhibition (LAI). These findings will allow us to guide future explorations of changes to these measures.
31 healthy individuals (21.06 ± 2.85 years) had SAI and LAI obtained thrice at 30-minute intervals in one session. To identify the minimum number of trials required to reliably elicit SAI and LAI, relative reliability was assessed at running intervals of 5 trials.
SAI had moderate–high, and LAI had high-excellent relative reliability. Both SAI and LAI had high amounts of measurement error. LAI had high relative reliability when only 5 frames of data were included, whereas SAI required ∼20–30 frames of data for the same. For both SAI and LAI, individual smallest detectable change was large but was reduced at the group level.
SAI and LAI can be used for both diagnostic purposes and to assess group level change but have limited utility in assessing within-individual changes.
These results can be used to inform future work regarding the utility of SAI and LAI, particularly in terms of their ability to identify particularly high or low values of afferent inhibition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Neuroimaging studies reveal structural and functional including neurochemical brain abnormalities in individuals with substance use disorders compared to healthy controls. However, whether and to ...what extent such dysfunction is reversible with abstinence remains unclear, and a review of studies with longitudinal within-subject designs is lacking. We performed a systematic review of longitudinal neuroimaging studies to explore putative brain changes associated with abstinence in treatment-seeking individuals with substance use disorders.
Following PRISMA guidelines, we examined articles published up to May 2021 that employed a neuroimaging technique and assessed neurobiological recovery in treatment-seeking participants at a minimum of two time-points separated by a period of abstinence (longer than 24 h apart) or significant reduction in drug use.
Forty-five studies met inclusion criteria. Encouragingly, in this limited but growing literature, the majority of studies demonstrated at least partial neurobiological recovery with abstinence. Structural recovery appeared to occur predominantly in frontal cortical regions, the insula, hippocampus, and cerebellum. Functional and neurochemical recovery was similarly observed in prefrontal cortical regions but also in subcortical structures. The onset of structural recovery appears to precede neurochemical recovery, which begins soon after cessation (particularly for alcohol); functional recovery may require longer periods of abstinence.
The literature is still growing and more studies are warranted to better understand abstinence-mediated neural recovery in individuals with substance use disorders. Elucidating the temporal dynamics between neuronal recovery and abstinence will enable evidence-based planning for more effective and targeted treatment of substance use disorders, potentially pre-empting relapse.
•Structural recovery occurred predominantly in frontal cortical regions, the insula, hippocampus, and cerebellum.•In addition to prefrontal cortical regions, functional recovery was also observed in midbrain, striatum, and thalamus.•Are specific brain regions more amenable to recovery, while other regions may be more impervious to change?.•Characterizing longitudinal changes may help identify novel targets for timely intervention.•Results provide hope for individuals with substance use disorders and encourage them to seek treatment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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Widespread skin allergies are of high societal concern. This pathology usually includes “histamine intolerance” and inflammatory processes affecting the skin. Oxidative stress, due to ...both intrinsic and environmental factors, leads to skin disorders, disease, and aging. Since the stratum corneum (SC) allows only small, lipophilic molecules to be absorbed through the skin, proteins, which are large amphoteric macromolecules, display limited bioavailability. The present study investigates the potential of chitosan nanoparticles as vehicle for two enzymes (catalytic proteins): catalase (CAT) and diamine oxidase (histaminase, DAO). Chitosan is an inexpensive, biocompatible, biodegradable, mucoadhesive, antibacterial, and antifungal biopolymer. Chitosan nanoparticles (CNP) have a high surface to volume ratio, hence high surface charge density and stronger biological activity than chitosan itself. CNP encapsulating DAO/CAT were prepared by using chitosans from different sources (shrimp and fungal). Nanoparticles were prepared by ionic complexation with sodium tripolyphosphate (TPP). Two different protein concentrations (0.5 mg/mL and 1.0 mg/mL) were investigated in the preparation of the nanoparticles. The resulting CNP were characterized by size (from 200 to 300 nm) and zeta potential (up to 9 mV) measurements, encapsulation efficiency (EE, up to 48%), loading capacity (LC, up to 42%), ratio of residual amino groups (RRAG, up to 14%), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and residual enzymatic activity. The antioxidant activity of the CNP encapsulating CAT was evaluated as well. The kinetics of protein release from the nanocomposites was monitored spectrophotometrically (for 160 h). Here we report that CAT was encapsulated with higher EE and residual enzymatic activity, while encapsulated DAO displayed better release profiles. Following encapsulation and release from CNP, both enzymes retained activity. The activities of DAO/CAT remained constant after five months in storage at −20 °C. These findings show that tailored nanosized chitosan affords enhancement to enzymes with low activity (like DAO) and shows promise as a carrier for therapeutic enzymes. Further investigations into its capability to increase their bioavailability are warranted.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
