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Iskalni niz: "avtor" (Voyko Kavcic) .

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1.
On the influence of aging on classification performance in the visual EEG oddball paradigm using statistical and temporal features
Nina Omejc, Manca Peskar, Aleksandar Miladinović, Voyko Kavcic, Sašo Džeroski, Uroš Marušič, 2023, izvirni znanstveni članek

Povzetek: The utilization of a non-invasive electroencephalogram (EEG) as an input sensor is a common approach in the field of the brain–computer interfaces (BCI). However, the collected EEG data pose many challenges, one of which may be the age-related variability of event-related potentials (ERPs), which are often used as primary EEG BCI signal features. To assess the potential effects of aging, a sample of 27 young and 43 older healthy individuals participated in a visual oddball study, in which they passively viewed frequent stimuli among randomly occurring rare stimuli while being recorded with a 32-channel EEG set. Two types of EEG datasets were created to train the classifiers, one consisting of amplitude and spectral features in time and another with extracted time-independent statistical ERP features. Among the nine classifiers tested, linear classifiers performed best. Furthermore, we show that classification performance differs between dataset types. When temporal features were used, maximum individuals’ performance scores were higher, had lower variance, and were less affected overall by within-class differences such as age. Finally, we found that the effect of aging on classification performance depends on the classifier and its internal feature ranking. Accordingly, performance will differ if the model favors features with large within-class differences. With this in mind, care must be taken in feature extraction and selection to find the correct features and consequently avoid potential age-related performance degradation in practice.
Ključne besede: aging, elderly, machine learning, visual oddball study, brain-computer interface
Objavljeno v DiRROS: 01.02.2023; Ogledov: 378; Prenosov: 201
.pdf Celotno besedilo (3,50 MB)
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2.
Neural bases of age-related sensorimotor slowing in the upper and lower limbs
Uroš Marušič, Manca Peskar, Kevin De Pauw, Nina Omejc, Gorazd Drevenšek, Bojan Rojc, Rado Pišot, Voyko Kavcic, 2022, izvirni znanstveni članek

Povzetek: With advanced age, there is a loss of reaction speed that may contribute to an increased risk of tripping and falling. Avoiding falls and injuries requires awareness of the threat, followed by selection and execution of the appropriate motor response. Using event-related potentials (ERPs) and a simple visual reaction task (RT), the goal of our study was to distinguish sensory and motor processing in the upper- and lower-limbs while attempting to uncover the main cause of age-related behavioral slowing. Strength (amplitudes) as well as timing and speed (latencies) of various stages of stimulus- and motor-related processing were analyzed in 48 healthy individuals (young adults, n = 24, mean age = 34 years; older adults, n = 24, mean age = 67 years). The behavioral results showed a significant age-related slowing, where the younger compared to older adults exhibited shorter RTs for the upper- (222 vs. 255 ms; p = 0.006, respectively) and the lower limb (257 vs. 274 ms; p = 0.048, respectively) as well as lower variability in both modalities (p = 0.001). Using ERP indices, age-related slowing of visual stimulus processing was characterized by overall larger amplitudes with delayed latencies of endogenous potentials in older compared with younger adults. While no differences were found in the P1 component, the later components of recorded potentials for visual stimuli processing were most affected by age. This was characterized by increased N1 and P2 amplitudes and delayed P2 latencies in both upper and lower extremities. The analysis of motor-related cortical potentials (MR) revealed stronger MRCP amplitude for upper- and a non-significant trend for lower limbs in older adults. The MRCP amplitude was smaller and peaked closer to the actual motor response for the upper- than for the lower limb in both age groups. There were longer MRCP onset latencies for lower- compared to upper-limb in younger adults, and a non-significant trend was seen in older adults. Multiple regression analyses showed that the onset of the MRCP peak consistently predicted reaction time across both age groups and limbs tested. However, MRCP rise time and P2 latency were also significant predictors of simple reaction time, but only in older adults and only for the upper limbs. Our study suggests that motor cortical processes contribute most strongly to the slowing of simple reaction time in advanced age. However, late-stage cortical processing related to sensory stimuli also appears to play a role in upper limb responses in the elderly. This process most likely reflects less efficient recruitment of neuronal resources required for the upper and lower extremity response task in older adults.
Ključne besede: aging, sensoriomotor integration, event-related potential, finger and foot responses, motor-related cortical potential
Objavljeno v DiRROS: 04.05.2022; Ogledov: 530; Prenosov: 426
.pdf Celotno besedilo (2,66 MB)
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3.
Učinkovitost računalniškega kognitivnega treninga v domovih starejših občanov
Uroš Marušič, Zdenka Milič Žepič, Voyko Kavcic, 2021, izvirni znanstveni članek

Povzetek: Ohranjanje in krepitev fi zičnega in kognitivnega zdravja je pri starejših osebah izziv, še posebej pri tistih, ki so podvržene pospešenim starostnim ali nevrodegenerativnim spremembam. Obstoječe nefarmakološke intervencije lahko stabilizirajo ali upočasnijo kognitivni upad, vendar se učinkovite preventivne tretmaje, ki bi zakasnili pojavnost simptomov, še raziskuje. Eden izmed nefarmakoloških tretmajev je kognitivni trening. Namen naše raziskave je bil oceniti izvedljivost in učinkovitost kognitivnega treninga z nalogo prostorske navigacije pri stanovalcih domov starejših občanov. Enaintrideset stanovalcev (povprečna starost 81,6 leta, razpon 69%94 let; povprečna ocena MoCA 22,8 točke, razpon 17%27; 7 moških) je bilo naključno razporejenih v kontrolno skupino ali intervencijsko skupino. Slednja je bila vključena v dvomesečni kognitivni trening (2-krat tedensko; skupaj 16 treningov), v katerem so udeleženci vadili učenje virtualnega labirinta. Vsi udeleženci raziskave so bili merjeni pred in po intervenciji na nevropsihološki ocenjevalni bateriji testov. Udeleženci kontrolne skupine niso prejeli nobene posebne obravnave in so tako sodelovali le na %pred in po% meritvah. Pomembne izboljšave so bile ugotovljene le pri Reyjevem testu slušno-besednega učenja (AVLT), kjer so udeleženci v intervencijski skupini značilno izboljšali svoj rezultat v primerjavi s kontrolno skupino. Kljub omejeni učinkovitosti kognitivnega treninga je bila naša intervencija izvedljiva in pozitivno sprejeta s strani večine udeležencev. Nadaljnje raziskave bi morale ovrednotiti dolgoročne učinke kognitivnega treninga na druge funkcionalne sposobnosti in aktivnosti vsakodnevnega življenja. Na splošno naša raziskava ponuja empirične dokaze, da je kognitivni trening sprejemljiv za stanovalce domov za starejše občane, in kar je najpomembneje, da lahko izboljša mnemonične kognitivne sposobnosti.
Ključne besede: staranje, kognitivni trening, prostorska navigacija, naloge, virtualni labirint, domovi za starejše občane
Objavljeno v DiRROS: 13.05.2021; Ogledov: 1087; Prenosov: 845
.pdf Celotno besedilo (333,30 KB)
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4.
Higher neural demands on stimulus processing after prolonged hospitalization can be mitigated by a cognitively stimulating environment
Uroš Marušič, Rado Pišot, Voyko Kavcic, 2021, izvirni znanstveni članek

Povzetek: Prolonge d periods of complete physical inactivity or bed rest trigger various alterations in the functional and metabolic levels of the human body. However, bed rest-related adaptations of the central nervous system are less known and thoroughly studied. The aim of this study was to investigate brain electrophysiological changes using event-related potentials (ERPs) after 14 days of bed rest and 12 consecutive sessions of computerized cognitive training (CCT). Sixteen older (Mage= 60 years) healthy volunteers were randomly divided into a CCT treatment group and an active control group. All participants performed ERP measurements based on the foveal visual presentation of a circle on a black background before and after bed rest. After 14 days of bed rest, participants in the control group showed increased peak P1 amplitude (p = .012), decreased P1 latency (p = .024), and increased P2 amplitude (p = .036), while the CCT group also showed decreased P1 latency (p = .023) and decreased P2 latency (p = .049). Our results suggest that, even from a central adaptation perspective, prolonged periods of physical inactivity or bed rest trigger additional neural recruitment and should therefore be minimized, and that CCT may serve as a tool to mitigate this. Future research should focus on other aspects of central nervous system adaptation following periods of immobilization/hospitalization to improve our knowledge of infl uence of physical inactivity and its eff ects on cortical activity and to develop appropriate countermeasures to mitigate functional dysregulation.
Ključne besede: aging, physical inactivity, immobilization, electroencephalography, EEG, computerized cognitive training
Objavljeno v DiRROS: 13.05.2021; Ogledov: 1143; Prenosov: 814
.pdf Celotno besedilo (820,21 KB)
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