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P8.22 Muscular activation patterns of a simple motor program during incongruency between proprioceptive and visual feedback
S100 distracters at the level of lemma representations. The comparison of raw and cleaned data confirmed that artefacts occur after 400 ms. However, additional artefacts within the first 400 ms suggest that early ERP components are not necessarily artefact-free and thus ask for caution. P8.19 Sensory-motor cortex reorganization in Alzheimer’s disease: an MEG study C. Salustri1 , F. Tecchio1 , F. Zappasodi2 , L. Tomasevic1 , M. Ercolani3 , F. Moffa3 , E. Cassetta3 , R. Squitti3 , P.M. Rossini3 1 LET’S ISTC-CNR, Fatebenefratelli Hospital, Isola Tiberina, Rome, Italy, 2 Dept. of Neurosciences and Imaging, Gabriele d’Annunzio University, Chieti, Italy, 3 Dept. of Neuroscience, AFaR, Fatebenefratelli Hospital, Isola Tiberina, Rome, Italy Introduction: Alzheimer’s disease (AD) is characterized by a progressive neuronal degeneration that causes a gradual loss of both cognitive and physical abilities. However, sensori-motor deficits start affecting AD patients only at a late stage of the disease. Objectives: Aim of our study was to evaluate possible signs of the high capability of the sensori-motor cortex to reorganize the neural circuitry that is being affected by the disease in nearby areas less affected by degeneration. Methods: We studied 16 AD patients and 16 controls by recording from sensorimotor brain areas their magnetoencephalographic (MEG) fields at rest and during contralateral median nerve stimulation. Latency of activation and position of the marker of primary somatosensory area devoted to hand control were estimated, in addition to spectral properties of these regions oscillatory activity at rest. Results: An unambiguous spatial shift of the patients’ sensori-motor generators, with no change in their latencies or strength. Interestingly, this reorganization appeared more evident in patients with less severe clinical condition (mini-mental state examination, MMSE, in the 20 25 range), regressing below significant difference from controls with worsened clinical state (MMSE = 7 20). Low-band activity (delta and theta bands) increased in patients with a linear behaviour. Conclusion: More evident signs of cerebral plasticity in AD patients with less severe clinical damage may suggest that the capability of sensorimotor regions to reorganize can contribute to the well known resistance of sensorimotor functions, which are imapaired in relative later stage of the disease. P8.20 Nicotine attenuates some 6-OHDA induced deficits of cognition and food reward in nucleus accumbens A. Ciobica1 , L. Hritcu1 , M. Padurariu2 , V. Bild2 1 Alexandru Ioan Cuza University, Iasi, Romania, 2 Gr. T. Popa University, Iasi, Romania Objective: Although dopaminergic mechanisms have been implicated in motivational processes, their role in appetitive conditioning remains poorly understood. The present study investigated the effects of dopamine (DA) depleting lesions of the nucleus accumbens on performance in a radial arm maze task. Effects of nicotine (0.3 mg/kg, i.p.) were also examined in animals with nucleus accumbens lesioned, in order to determine the influence of nicotine on dopamine release in the nucleus accumbens. Methods: Rats received bilateral infusions of either phosphate-buffered saline (shams) or 6-hydroxydopamine (lesions) directly into the nucleus accumbens. Two weeks later, a radial 8 arms maze task was used for memory assessment in male Wistar rats. Nicotine (0.3 mg/kg, i.p.) was administrated 7 days after the last training in radial arm maze task and the test was repeated. Results: The results indicate that nucleus accumbens lesions resulted in a significant impairment of both working and reference memory tested by means of radial arm-maze task, suggesting significant effects of spatial memory. Also the rat’s motivation for food reward was extremely reduced. Administration of nicotine (0.3 mg/kg, i.p.) significantly attenuated this impairment, by reducing both working and reference memory errors and augmenting food searching and intake. Conclusions: These data are compatible with the hypothesis that nucleus accumbens dopamine serves to guide conditioned approach to appetitive cues. Since the facilitatory effects of nicotine was seen in the nucleus accumbens-lesion group, it is possible for nicotine to induced improvements on accumbal DA release, with effects on memory processes and food reward.
Poster presentations: Poster session 8. Ageing, dementia, cognitive functions P8.21 The importance of some cardiovascular risk factors for dementia M. Padurariu1 , A. Ciobica2 , C. Stefanescu1 , C. Joacabine1 1 Gr. T. Popa University, Iasi, Romania, 2 Alexandru Ioan Cuza, Iasi, Romania Background: Mild cognitive impairment (MCI) is an early stage of cognitive decline that has a major risk of converting to dementia. It is possible that an early detection and correction of MCI could lead to a significant rate of reversion. Cardiovascular pathology appears to have a major impact in cognitive decline, and it is clear that early identification and correction of cardiovascular morbidity could have a major protective impact on cognitive functioning. In this way, our study was conducted in order to identify some cardiovascular risk factors among patients with cognitive decline (Alzheimer disease-AD or MCI) and to find if there is any correlation with the degree of cognitive decline. Methods: We evaluated several cardiovascular risk factors such as hypertension, body mass index, cholesterol, history of smoking, alcohol consumption and diabetes mellitus in patients with MCI and AD, compared with an aged-matched control group. Results: Regarding the body mass index, we observed a decrease in both patients with MCI and AD, while the statistical analysis of cholesterol revealed a significant decrease in both MCI and AD groups, in comparison with the control group. However, post hoc analysis revealed no significantly statistical differences between MCI and AD groups. The systolic blood pressure was also increased in the patients with MCI and AD. Also, as in the case of cholesterol levels, post hoc analysis revealed no significantly statistical differences between MCI and AD groups. Pearson’s correlation also showed significant connections between the cardiovascular risk factors and the results of the cognitive evaluation through Mini-Mental State Examination (MMSE) and Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-Cog). Conclusions: Cognitive regression can be a result of the cardiovascular distress. This could have an important impact on the management of dementia. P8.22 Muscular activation patterns of a simple motor program during incongruency between proprioceptive and visual feedback O. Christ1 , K. Wolff1 , A. Seehaus2 , C. Weber1 Department of Work and Engineering Psychology, Technische Universit¨ at Darmstadt, Darmstadt, Germany, 2 Department of Biology, Technische Universit¨ at Darmstadt, Darmstadt, Germany
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Introduction: Studies describing the effect of incongruence between proprioceptive and visual feedback (IPVF) showed a change in perception threshold and quality (Blakemore et al., 2000; McCabe et al., 2005). Those effects are explained theoretically by the concept of an efference copy (Holst & Mittelstaedt, 1950) in motor control. Regarding psychometric parameters an increase of reaction times and errors due to IPVF (Jay & Hubbold, 2005; Kalmus et al., 1960) was observable and suggested the occurrence of motor learning. Objectives: Because muscular consequences of IPVF are not described yet, this study aims to look for the effects of IPVF on muscular activity and patterns. Methods: 48 right handed subjects performed 200 keystrokes on a keyboard. Reaction times, mental state and event related electromyography (EMG) of extensor- and flexor-muscles in both arms were recorded in four visual delay (VD) conditions (system, +50 ms, +100 ms, + 150 ms) during a key press. The arms were covered. Subjects saw their movements on a computer monitor. The task was to press one of the eight keys, while the keyboard was moving. Results: No changes in mental state or reaction times were observable. The muscular activity showed a significant change during VD in the coactivation pattern of the antagonist EMG in the right (p < 0.001, partial h2 = 0.490) and the left (p < 0.001, partial h2 = 0.972) arm with strong effects in the 50 ms (d = 1.8) and the 100 ms (d = 1.5) VD condition. Conclusions: The effect of IPVF on the muscular co-activation pattern in both arms may be described as a psychophysiological correlate of motor learning (Osu et al., 2002) and support decreased performance through an adaptation process (Jay & Hubbold, 2005; Kalmus et al., 1960). While the changes in the active arm may be explained through the discrepancy between efference copy (or prediction of movement) and actual sensory consequences (McCabe et al., 2005) further investigation is needed to describe higher effects in the passive limb.
Poster presentations: Poster session 8. Ageing, dementia, cognitive functions P8.21 The importance of some cardiovascular risk factors for dementia M. Padurariu1 , A. Ciobica2 , C. Stefanescu1 , C. Joacabine1 1 Gr. T. Popa University, Iasi, Romania, 2 Alexandru Ioan Cuza, Iasi, Romania Background: Mild cognitive impairment (MCI) is an early stage of cognitive decline that has a major risk of converting to dementia. It is possible that an early detection and correction of MCI could lead to a significant rate of reversion. Cardiovascular pathology appears to have a major impact in cognitive decline, and it is clear that early identification and correction of cardiovascular morbidity could have a major protective impact on cognitive functioning. In this way, our study was conducted in order to identify some cardiovascular risk factors among patients with cognitive decline (Alzheimer disease-AD or MCI) and to find if there is any correlation with the degree of cognitive decline. Methods: We evaluated several cardiovascular risk factors such as hypertension, body mass index, cholesterol, history of smoking, alcohol consumption and diabetes mellitus in patients with MCI and AD, compared with an aged-matched control group. Results: Regarding the body mass index, we observed a decrease in both patients with MCI and AD, while the statistical analysis of cholesterol revealed a significant decrease in both MCI and AD groups, in comparison with the control group. However, post hoc analysis revealed no significantly statistical differences between MCI and AD groups. The systolic blood pressure was also increased in the patients with MCI and AD. Also, as in the case of cholesterol levels, post hoc analysis revealed no significantly statistical differences between MCI and AD groups. Pearson’s correlation also showed significant connections between the cardiovascular risk factors and the results of the cognitive evaluation through Mini-Mental State Examination (MMSE) and Alzheimer’s Disease Assessment Scale-Cognitive (ADAS-Cog). Conclusions: Cognitive regression can be a result of the cardiovascular distress. This could have an important impact on the management of dementia. P8.22 Muscular activation patterns of a simple motor program during incongruency between proprioceptive and visual feedback O. Christ1 , K. Wolff1 , A. Seehaus2 , C. Weber1 Department of Work and Engineering Psychology, Technische Universit¨ at Darmstadt, Darmstadt, Germany, 2 Department of Biology, Technische Universit¨ at Darmstadt, Darmstadt, Germany
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Introduction: Studies describing the effect of incongruence between proprioceptive and visual feedback (IPVF) showed a change in perception threshold and quality (Blakemore et al., 2000; McCabe et al., 2005). Those effects are explained theoretically by the concept of an efference copy (Holst & Mittelstaedt, 1950) in motor control. Regarding psychometric parameters an increase of reaction times and errors due to IPVF (Jay & Hubbold, 2005; Kalmus et al., 1960) was observable and suggested the occurrence of motor learning. Objectives: Because muscular consequences of IPVF are not described yet, this study aims to look for the effects of IPVF on muscular activity and patterns. Methods: 48 right handed subjects performed 200 keystrokes on a keyboard. Reaction times, mental state and event related electromyography (EMG) of extensor- and flexor-muscles in both arms were recorded in four visual delay (VD) conditions (system, +50 ms, +100 ms, + 150 ms) during a key press. The arms were covered. Subjects saw their movements on a computer monitor. The task was to press one of the eight keys, while the keyboard was moving. Results: No changes in mental state or reaction times were observable. The muscular activity showed a significant change during VD in the coactivation pattern of the antagonist EMG in the right (p < 0.001, partial h2 = 0.490) and the left (p < 0.001, partial h2 = 0.972) arm with strong effects in the 50 ms (d = 1.8) and the 100 ms (d = 1.5) VD condition. Conclusions: The effect of IPVF on the muscular co-activation pattern in both arms may be described as a psychophysiological correlate of motor learning (Osu et al., 2002) and support decreased performance through an adaptation process (Jay & Hubbold, 2005; Kalmus et al., 1960). While the changes in the active arm may be explained through the discrepancy between efference copy (or prediction of movement) and actual sensory consequences (McCabe et al., 2005) further investigation is needed to describe higher effects in the passive limb.