Biomedical subjects

Claudio Del Percio

Publications and source records attributed to Claudio Del Percio.

15 recordsLinked to original sources

PubMed2006

Apolipoprotein E and alpha brain rhythms in mild cognitive impairment: a multicentric electroencephalogram study.

OBJECTIVE: Relationships between the apolipoprotein E epsilon4 allele and electroencephalographic (EEG) rhythmicity have been demonstrated in Alzheimer's disease (AD) patients but not in the preclinical stage prodromic to it, namely, mild cognitive impairment (MCI). The present multicentric EEG study tested the hypothesis that presence of epsilon4 affects sources of resting EEG rhythms in both MCI and AD subjects. METHODS: We enrolled 89 MCI subjects (34.8% with epsilon4) and 103 AD patients (50.4% with epsilon4). Resting eyes-closed EEG data were recorded for all subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography. RESULTS: Results showed that amplitude of alpha 1 and 2 sources in occipital, temporal, and limbic areas was lower in subjects carrying the epsilon4 allele than in those not carrying the epsilon4 allele (p < 0.01). This was true for both MCI and AD. For the first time to our knowledge, a relationship was shown between ApoE genotype and global neurophysiological phenotype (ie, cortical alpha rhythmicity) in a preclinical AD condition, MCI, in addition to clinically manifest AD. INTERPRETATION: Such a demonstration motivates future genotype-EEG phenotype studies for the early prediction of AD conversion in individual MCI subjects.

Aged↗

PubMed2006

Sources of cortical rhythms in adults during physiological aging: a multicentric EEG study.

This electroencephalographic (EEG) study tested whether cortical EEG rhythms (especially delta and alpha) show a progressive increasing or decreasing trend across physiological aging. To this aim, we analyzed the type of correlation (linear and nonlinear) between cortical EEG rhythms and age. Resting eyes-closed EEG data were recorded in 108 young (Nyoung; age range: 18-50 years, mean age 27.3+/-7.3 SD) and 107 elderly (Nold; age range: 51-85 years, mean age 67.3+/-9.2 SD) subjects. The EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography (LORETA). Statistical results showed that delta sources in the occipital area had significantly less magnitude in Nold compared to Nyoung subjects. Similarly, alpha 1 and alpha 2 sources in the parietal, occipital, temporal, and limbic areas had significantly less magnitude in Nold compared to Nyoung subjects. These nine EEG sources were given as input for evaluating the type (linear, exponential, logarithmic, and power) of correlation with age. When subjects were considered as a single group there was a significant linear correlation of age with the magnitude of delta sources in the occipital area and of alpha 1 sources in occipital and limbic areas. The same was true for alpha 2 sources in the parietal, occipital, temporal, and limbic areas. In general, the EEG sources showing significant linear correlation with age also supported a nonlinear correlation with age. These results suggest that the occipital delta and posterior cortical alpha rhythms decrease in magnitude during physiological aging with both linear and nonlinear trends. In conclusion, this new methodological approach holds promise for the prediction of dementia in mild cognitive impairment by regional source rather than surface EEG data and by both linear and nonlinear predictors.

Adolescent↗

PubMed2005

Sources of cortical rhythms change as a function of cognitive impairment in pathological aging: a multicenter study.

OBJECTIVE: The present study tested the hypothesis that cortical electroencephalographic (EEG) rhythms. change across normal elderly (Nold), mild cognitive impairment (MCI), and Alzheimer's disease (AD) subjects as a function of the global cognitive level. METHODS: Resting eyes-closed EEG data were recorded in 155 MCI, 193 mild AD, and 126 age-matched Nold subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by LORETA. RESULTS: Occipital delta and alpha 1 sources in parietal, occipital, temporal, and 'limbic' areas had an intermediate magnitude in MCI subjects compared to mild AD and Nold subjects. These five EEG sources presented both linear and nonlinear (linear, exponential, logarithmic, and power) correlations with the global cognitive level (as revealed by mini mental state examination score) across all subjects. CONCLUSIONS: Cortical EEG rhythms change in pathological aging as a function of the global cognitive level. SIGNIFICANCE: The present functional data on large populations support the 'transitional hypothesis' of a shadow zone across normality, pre-clinical stage of dementia (MCI), and AD.

Aged↗

PubMed2005

Genotype (cystatin C) and EEG phenotype in Alzheimer disease and mild cognitive impairment: a multicentric study.

Previous findings demonstrated that haplotype B of CST3, the gene coding for cystatin C, is a recessive risk factor for late-onset Alzheimer's disease (AD; Finckh, U., von der Kammer, H., Velden, J., Michel, T., Andresen, B., Deng, A., Zhang, J., Muller-Thomsen, T., Zuchowski, K., Menzer, G., Mann, U., Papassotiropoulos, A., Heun, R., Zurdel, J., Holst, F., Benussi, L., Stoppe, G., Reiss, J., Miserez, A.R., Staehelin, H.B., Rebeck, G.W., Hyman, B.T., Binetti, G., Hock, C., Growdon, J.H., Nitsch, R.M., 2000. Genetic association of the cystatin C gene with late-onset Alzheimer disease. Arch. Neurol. 57, 1579-1583). In the present multicentric electroencephalographic (EEG) study, we analyzed the effects of CST3 haplotypes on resting cortical rhythmicity in subjects with AD and mild cognitive impairment (MCI) with the hypothesis that sources of resting EEG rhythms are more impaired in carriers of the CST3 B haplotype than non-carriers. We enrolled a population of 84 MCI subjects (42% with the B haplotype) and 65 AD patients (40% with the B haplotype). Resting eyes-closed EEG data were recorded in all subjects. EEG rhythms of interest were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). EEG cortical sources were estimated by low-resolution brain electromagnetic tomography (LORETA). Results showed that the amplitude of alpha 1 (parietal, occipital, temporal areas) and alpha 2 (occipital area) was statistically lower in CST3 B carriers than non-carriers (P < 0.01). Whereas there was a trend towards statistical significance that amplitude of occipital delta sources was stronger in CST3 B carriers than in non-carriers. This was true for both MCI and AD subjects. The present findings represent the first demonstration of relationships between the AD genetic risk factor CST3 B and global neurophysiological phenotype (i.e., cortical delta and alpha rhythmicity) in MCI and AD subjects, prompting future genotype-EEG phenotype studies for the early prediction of AD conversion in individual MCI subjects.

Adult↗

PubMed2005

Alpha rhythms in mild dements during visual delayed choice reaction time tasks: a MEG study.

Can simple delayed response tasks affect latency and amplitude of magnetoencephalographic midline alpha rhythms (6-12 Hz) in early dementia? We recruited 15 mild Alzheimer's disease (AD) and 10 vascular dementia (VaD) patients (paired mini mental state exam of 17-24). The control groups comprised 18 young and 22 elderly normal subjects. In the first task, a simple "cue" stimulus (one bit) was memorized along a brief delay period (3.5-5.5s) up to a "go" stimulus triggering (right or left) button press. In the second task, the "cue" stimulus remained available along the delay period. Event-related reduction in power of the alpha rhythms indexed the cortical activation (event-related desynchronization, ERD) for the trials associated with correct behavioral responses. Behavioral performances to both tasks were lower in the AD and VaD patients than in the normal subjects. In particular, just four AD and five VaD patients executed a sufficient amount of correct responses for the alpha ERD analysis, so they were included in a unique group. In both tasks, the alpha ERD peak was later in latency in the demented and normal elderly subjects than in the normal young subjects. Furthermore, the alpha ERD peak was stronger in amplitude in the demented patients than in the normal subjects. These results suggest that simple delayed response tasks during physiological recordings are quite difficult for patients even at an early dementia stage. Such difficulty may induce the abnormal amount of the related cortical activation in dementia as revealed by the alpha ERD.

Adolescent↗

PubMed2005

Human alpha rhythms during visual delayed choice reaction time tasks: a magnetoencephalography study.

Magnetoencephalography (MEG) includes fast and comfortable recording procedures very suitable for the neurophysiological study of cognitive functions in aged people. In this exploratory MEG study in normal young adults, we tested whether very simple short-term memory (STM) demands induce visible changes in amplitude and latency of surface alpha rhythms. Two delayed response tasks were used. In the STM condition, a simple cue stimulus (one bit) was memorized along a brief delay period (3.5-5.5 s). In the control (no short-term memory; NSTM) condition, the cue stimulus remained available along the delay period. To make extremely simple the tasks, the explicit demand was visuospatial but the retention could be also based on phonological and somatomotor coding. Compared to the control condition, the amplitude of the alpha 1 (6-8 Hz) ERD decreased in the left hemisphere, whereas the amplitude of the alpha 2 (8-10 Hz) and alpha 3 (10-12 Hz) event-related desynchronization (ERD) increased in right and left parietal areas, respectively. Furthermore, the latency of the alpha ERD peak was slightly but significantly (P < 0.05) later in STM compared to control condition. In conclusion, whole-head MEG technology and very simple STM demands revealed significant changes of human neuromagnetic alpha rhythms in normal young adults.

Adult↗

PubMed2004

Human cortical rhythms during visual delayed choice reaction time tasks. A high-resolution EEG study on normal aging.

Neuroimaging cognitive study of aging requires simple tasks ensuring a high rate of correct performances even in stressful neurophysiological settings. Here two simple delayed choice reaction time tasks were used to unveil event-related desynchronization (ERD) of theta (4-6 Hz) and alpha (6-12 Hz) electroencephalographic rhythms across normal aging. In the first condition, a cue stimulus (one bit) was memorized along a brief delay period (3.5-5.5 s). The explicit demand was visuo-spatial, but the retention could be also based on phonological and somatomotor coding. In the second condition, the cue stimulus remained available along the delay period. Correct performances were higher than 95% in both groups and tasks, although they were significantly better in young than elderly subjects (P < 0.03). During the delay period, theta and alpha ERD accompanying correct responses were recognized in the two groups, the alpha ERD being stronger and prolonged during the memory than non-memory task. On the other hand, the fronto-parietal theta and parietal alpha ERD were stronger in young than elderly subjects during both tasks. Notably, the frontal alpha ERD was negligible in elderly subjects. In conclusion, the present simple tasks unveiled in elderly compared to young subjects (i) a weaker involvement of (para)hippocampal-cortical circuits as revealed by theta ERD and (ii) a weaker involvement of "executive" thalamo-cortical circuits as revealed by frontal alpha ERD. These effects might worsen behavioral performances to the simple cognitive tasks with age. The present protocol is promising for the neuroimaging study of pathological aging.

Adult↗

PubMed2004

Attentional processes and cognitive performance during expectancy of painful galvanic stimulations: a high-resolution EEG study.

In the present high-resolution electroencephalographic (EEG) study, an omitted-stimulus paradigm induced a strong expectancy for a predictable painful stimulation (nonpainful in the control condition). During the expectancy of pain, concurrent cognitive demands were superimposed. The aim was to investigate the effects on primary sensorimotor and central midline areas of the competition among concurrent attentional processes related to cognition and pain expectancy, as indexed by behavioral performance and EEG data. A main issue was whether cognitive performance decreases, due to a re-allocation of attentional resources on primary sensorimotor and midline areas for the anticipation of pain. Behavioral results showed no differences in the cognitive (working memory) performance during the expectancy of nonpainful versus painful stimulations. In parallel, anticipatory event-related potentials (ERPs) were negligible in line with a low emotional reactivity/alertness as revealed by heart rate deceleration (HRD), skin conductance response (SCR), and low-band (6-10Hz) alpha EEG oscillations. In contrast, high-band alpha EEG oscillations (10-12Hz) over the contralateral primary sensorimotor cortex decreased more during the expectancy of painful compared to nonpainful stimuli, in line with an increased anticipatory preparation of the somatosensory channel. These findings provide further evidence on the fact that attentional processes at the basis of cognition can be defended by the anticipation of pain, at least when the incoming painful stimuli are repetitive and predictable. This happens even if the brain increases preparatory processes of the specific sensory channel to be targeted by the painful stimulus.

Adult↗

PubMed2004

Sub-second "temporal attention" modulates alpha rhythms. A high-resolution EEG study.

In the present high-resolution electroencephalographic (EEG) study, event-related desynchronization/synchronization (ERD/ERS) of alpha rhythms was computed during an S1-S2 paradigm, in which a visual cue (S1) predicted a SHORT (600 ms) or LONG (1400 ms) foreperiod, preceding a visual go stimulus (S2) triggering right or left finger movement. Could orienting attention to a selective point in time influence the alpha rhythms as a function of the SHORT vs. LONG foreperiod? Stronger selective attentional modulations were predicted for the SHORT than LONG condition. EEG data from 54 channels were "depurated" from phase-locked visual evoked potentials and spatially enhanced by surface Laplacian estimation (i.e., final data analysis was conducted on 16 subjects having a sufficient number of artifact-free EEG single trials). Low-band alpha rhythms (about 6-10 Hz) were supposed to be related to anticipatory attentional processes, whereas high-band alpha rhythms (10-12 Hz) would indicate task-specific visuo-motor processes. Compared to the LONG condition (foreperiod), the SHORT condition induced a quicker and stronger ERS at low-band alpha rhythm (about 6-8 Hz) over midline and bilateral prefrontal, sensorimotor, and posterior parietal areas. In contrast, the concomitant high-band alpha (about 10-12 Hz) ERD/ERS showed no significant difference between the two conditions. In conclusion, temporal attention for a sub-second delay (800 ms) did modulate low-band alpha rhythm over large regions of both cortical hemispheres.

Adolescent↗

PubMed2004

Mapping distributed sources of cortical rhythms in mild Alzheimer's disease. A multicentric EEG study.

The study aimed at mapping (i) the distributed electroencephalographic (EEG) sources specific for mild Alzheimer's disease (AD) compared to vascular dementia (VaD) or normal elderly people (Nold) and (ii) the distributed EEG sources sensitive to the mild AD at different stages of severity. Resting EEG (10-20 electrode montage) was recorded from 48 mild AD, 20 VaD, and 38 Nold subjects. Both AD and VaD patients had 24-17 of mini mental state examination (MMSE). EEG rhythms were delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), and beta 2 (20-30 Hz). Cortical EEG sources were modeled by low resolution brain electromagnetic tomography (LORETA). Regarding issue i, there was a decline of central, parietal, temporal, and limbic alpha 1 (low alpha) sources specific for mild AD group with respect to Nold and VaD groups. Furthermore, occipital alpha 1 sources showed a strong decline in mild AD compared to VaD group. Finally, distributed theta sources were largely abnormal in VaD but not in mild AD group. Regarding issue ii, there was a lower power of occipital alpha 1 sources in mild AD subgroup having more severe disease. Compared to previous field studies, this was the first investigation that illustrated the power spectrum profiles at the level of cortical (macroregions) EEG sources in mild AD patients having different severity of the disease with respect to VaD and normal subjects. Future studies should evaluate the clinical usefulness of this approach in early differential diagnosis, disease staging, and therapy monitoring.

Aged↗

PubMed2004

Human cortical EEG rhythms during long-term episodic memory task. A high-resolution EEG study of the HERA model.

Many recent neuroimaging studies of episodic memory have indicated an asymmetry in prefrontal involvement, with the left prefrontal cortex more involved than the right in encoding, the right more than the left in retrieval (hemispheric encoding and retrieval asymmetry, or HERA model). In this electroencephalographic (EEG) high-resolution study, we studied brain rhythmicity during a visual episodic memory (recognition) task. The theta (4-6 Hz), alpha (6-12 Hz) and gamma (28-48 Hz) oscillations were investigated during a visuospatial long-term episodic memory task including an encoding (ENC) and retrieval (RET) phases. During the ENC phase, 25 figures representing interiors of buildings ("indoor") were randomly intermingled with 25 figures representing landscapes ("landscapes"). Subject's response was given at left ("indoor") or right ("landscapes") mouse button. During the RET phase (1 h later), 25 figures representing previously presented "indoor" pictures ("tests") were randomly intermingled with 25 figures representing novel "indoor" ("distractors"). Again, a mouse response was required. Theta and alpha EEG results showed no change of frontal rhythmicity. In contrast, the HERA prediction of asymmetry was fitted only by EEG gamma responses, but only in the posterior parietal areas. The ENC phase was associated with gamma EEG oscillations over left parietal cortex. Afterward, the RET phase was associated with gamma EEG oscillations predominantly over right parietal cortex. The predicted HERA asymmetry was thus observed in an unexpected location. This discrepancy may be due to the differential sensitivity of neuroimaging methods to selected components of cognitive processing. The strict relation between gamma response and perception suggests that retrieval processes of long-term memory deeply impinged upon sensory representation of the stored material.

Adult↗

PubMed2004

Human cortical responses during one-bit short-term memory. A high-resolution EEG study on delayed choice reaction time tasks.

OBJECTIVE: We investigated whether a very simple short-term memory (STM) demand induces a visible change of EEG rhythms over the two hemispheres. METHODS: High-resolution EEG was obtained in young adults during two delayed choice reaction time tasks. In the STM condition, a simple cue stimulus (one bit) was memorized along a brief delay period (3.5-5.5 s). The task was visuo-spatial in nature. RESULTS: In the control (NSTM) condition, the cue stimulus remained available along the delay period. Compared to the control condition, the theta power (4-6 Hz) decreased in left frontal and bilateral parietal areas (delay period). Furthermore, low alpha power (6-8 Hz) decreased in bilateral frontal and left parietal areas, while high alpha power (10-12 Hz) decreased in the left fronto-parietal areas. CONCLUSIONS: The decrease of the alpha power is as an expression of the efficient information transfer within thalamo-cortical pathways. The significance of the study stands in the fact that even a very simple STM task (only one bit to be memorized) revealed changes in fronto-parietal theta and alpha rhythms.

Adult↗

PubMed2004

Cortical sensorimotor interactions during the expectancy of a go/no-go task: effects of painful stimuli.

The intent of this electroencephalography study was to investigate the competition between cortical nociceptive and cognitive-motor processes preceding sensorimotor interactions. Sensorimotor expectancy processes to painful stimulation and motor go/no-go demands were indexed over primary sensorimotor and midline cortical areas by contingent negative variation (CNV). Before the sensorimotor interaction, CNV was observed over midline posterior and bilateral central areas. Early expectancy of painful stimulation and the go/no-go task induced an evident midline posterior CNV. During the late expectancy period. CNV extended to the right central area contralateral to the stimulation. These findings suggest a sequential activation of midline posterior and primary sensorimotor areas contralateral to the painful stimulation as a reflection of the enhanced nociceptive processes preceding painful sensorimotor interactions.

Adult↗

PubMed2003

Transient human cortical responses during the observation of simple finger movements: a high-resolution EEG study.

High-resolution event-related potentials (ERPs) were used to model the hemispherical representation of the transient cortical responses relating to the observation of movement during execution (right or left aimless finger extension). Subjects were seated in front of the observed person and looked at both their own and the observer's hand to receive similar visual feedback during the two conditions. In a visual control condition, a diode light moved at the observed person's hand. A first potential accompanying the movement execution peaked at about +110 msec over the contralateral somatomotor areas. It was followed by a potential (P300) peaking at about +350 msec over the central midline. In contrast, the potentials accompanying the movement observation peaked later over parietal-occipital other than somatomotor areas (N200 peak, +200 msec; P300 peak, +400 msec). Notably, the N200 was maximum in left parietal area whereas the P300 was maximum in right parietal area regardless the side of the movement. They markedly differed by the potentials following the displacement of the diode light. These results suggest a rapid time evolution (approximately 200-400 msec) of the cortical responses characterizing the observation of aimless movements (as opposite to grasping or handling). The execution of these movements would mainly involve somatomotor cortical responses and would be scarcely founded on the visual feedback. In contrast, the observation of the same movements carried out by others would require dynamical responses of somatomotor and parietal-occipital areas (especially of the right hemisphere), possibly for a stringent visuospatial analysis of the motor event.

Adult↗

PubMed2002

Human cortical electroencephalography (EEG) rhythms during the observation of simple aimless movements: a high-resolution EEG study.

In the present high-resolution electroencephalographic (EEG) study, we computed event-related desynchronization and synchronization (ERD/ERS) of alpha (about 10 Hz) and beta (about 20 Hz) rhythms in association with the execution (with visual feedback) and observation of brisk unilateral right and left aimless finger movements. A first scope was to test the topographical "functional equivalence" of cortical rhythmicity related to movement execution and observation, which would represent an ideal cortical observation/execution matching system. A second scope was to evaluate the hypothesis of a left or right hemisphere prevalence of the cortical rhythmicity related to the movement observation compared to the movement execution. EEG (128 electrodes) was recorded in 10 healthy right-handed volunteers. Surface Laplacian estimation spatially enhanced EEG data over a MRI-constraint head model. Under both conditions, ERD peaked during the movement execution or observation and was replaced by a ERS "rebound" or "recovery," which peaked during the postevent period. Topographical results are in favor of a "functional equivalence" (i.e., similar ERD/ERS values in magnitude and timing) of alpha and beta rhythmicity in central scalp regions overlying premotor/primary sensorimotor cortex. On the contrary, the functional equivalence of alpha rhythmicity was negligible (i.e., different ERD/ERS values in magnitude and timing) in parietal-occipital scalp regions overlying posterior parietal and parieto-occipital cortex, which could be the neural substrate to distinguish among the own motor intensions and others' aimless movements (i.e., visuomotor transformation integrated with sensorimotor, postural, and kinematics representations). Finally, the pattern of hemispherical cortical rhythmicity did not support a "simple concentration" of movement observation functions in the left or right hemisphere.

Adult↗