Publications (14)42.02 Total impact
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Article: Sleep-dependent consolidation of motor skills in patients with narcolepsy-cataplexy.
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ABSTRACT: Background and Objectives: This study investigated whether the altered organization of post-training sleep in patients with narcolepsy-cataplexy (NC) is associated with a lower off-line improvement in the consolidation of motor skills compared with normal subjects. Study Design: Fourteen drug-naive NC patients, fulfilling the international clinical and polysomnographic diagnostic criteria, and 14 individually-matched controls underwent training at a sequential finger tapping task (FTT) and were re-tested on the next morning (after a night with polysomnographic recording) and after another six nights (spent at home). Setting: Training and retrieval sessions were performed in a controlled laboratory setting. Results: FTT performance was worse in NC patients than controls at training and at both retrieval sessions and showed a fairly different time course (slower than in controls) of consolidation. Several sleep indices (lower values of stage-2 NREM sleep and SWS) were compatible with a lower effectiveness of sleep for consolidation of motor skills in NC patients, although no statistically significant relationship was found between such indices and improvement rate. Conclusion: The consolidation process of motor skills results less effective in NC patients since training and slower than in normal subjects over the week following training. The wider variations in performance scores and sleep parameters of post.-training night in NC patients relative to controls suggest that a) the lower initial consolidation may be due to a less effective encoding consequent to altered prior sleep, and b) the consolidation process over the 24 h following training is negatively influenced not only by the altered characteristics of post-training sleep, but also by the daytime sleepiness following training.Archives italiennes de biologie 06/2012; 150(2-3):185-93. · 1.29 Impact Factor -
Article: Minimal hepatic encephalopathy: follow-up 10 years after successful liver transplantation.
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ABSTRACT: The long-term effect of liver transplantation (LT) on cognitive functions and the complete reversibility of minimal hepatic encephalopathy are poorly documented. Much evidence indicates that spatial attention improves starting from the immediate period after LT. However, at least in the first 2 years, some cognitive defects seem to persist to some degree, especially for supramodal nonverbal cognitive functions. The aim of this study is to investigate (i) whether the improvements observed in the perioperative period fluctuate or remain stable 10 years after LT and (ii) whether the functions that have been found defective also improve. We called patients previously included in a prospective study (Mattarozzi et al., Arch Neurol 2004; 61: 242) for a further neuropsychological evaluation. We compared the cognitive evaluation after 7 to 10 years with previous data gathered 6 and 18 months after LT. The improvements obtained in the first 2 years after transplantation remain stable during the 7 to 10 years thereafter, especially for visuospatial attention, F(12,96) 1.70; P=0.04 and selective attention, F(6,66) 3.51; P=0.005. Furthermore, these findings also seem to suggest an improvement in supramodal cognitive functions, such as spatial planning intelligence, measured by the Elithorn Maze Test, F(3,33) 7.42; P=0.002. Verbal short-term memory, F(3,33) 3.69; P=0.038, and visuospatial short-term memory, F(6,64) 2.97; P=0.013, show a more fluctuating trend over time. Despite the risk of surgery, the neurotoxicity of immunosuppression therapy, and the effects of aging and related comorbidities, our data indicate that LT is able to significantly improve patients' cognitive functions in the long term.Transplantation 01/2012; 93(6):639-43. · 4.00 Impact Factor -
Article: Overnight distribution and motor characteristics of REM sleep behaviour disorder episodes in patients with narcolepsy-cataplexy.
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ABSTRACT: The study aimed to examine the temporal distribution of episodes of REM sleep behaviour disorder (RBD) over the night and their motor and polysomnographic (PSG) characteristics in patients with narcolepsy-cataplexy (NC). Full-night video-PSG recordings of a continuous series of 37 drug-naïve NC patients with clinically-documented RBD were examined to detect the occurrences of RBD episodes (disclosed in 27 patients) and to classify their related PSG and motor behaviour features. RBD episodes occurred with comparable frequency in REM sleep periods of the first and second halves of the night, regardless of the length of REM periods, patients' age or disease duration. Vocalisations and pantomimes occurred in comparable proportions of RBD episodes in the two halves of the night, while aggressive-violent movements were significantly more frequent in RBD episodes of the second half of the night. No sleep parameter significantly differed in patients with RBD occurring in the first/second/neither half of the night. RBD episodes (a) are not an every night phenomenon in NC patients with clinically documented RBD, regardless of their age or disease duration; (b) can occur in any period of REM sleep, regardless of length; and (c) display less violent-aggressive motor features when they occur in the first half of the night. Multi-night studies with dream-report collection may disclose whether this overnight variation in the violent-aggressive features in RBD episodes of NC patients is associated with a time-of-night-related variation in dream content.Sleep Medicine 06/2011; 12(7):635-40. · 3.40 Impact Factor -
Article: Insomnia cycling with a 42-day infradian period: evidence for two uncoupled circadian oscillators?
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ABSTRACT: To describe the unique case of a middle-aged woman with severe insomnia recurring with a regular infradian period without any other significant clinical condition. To infer the existence of a circadian dysfunction modeled according to the physical phenomenon of the "beats." A two-year prospective observation by means of a sleep log was performed during the patient's normal life. She underwent one month of motor activity recording and also polysomnography, circadian rhythm of body core temperature and psychiatric evaluation during periods with and without insomnia. Visual inspection of the 293-day plot of the sleep log disclosed a regular 42-day rhythm of insomnia recurrence confirmed by a Discrete Fourier Transform. During the periods of insomnia, lasting 5-7days, only moderate mood symptoms (depressive overlapping hypomaniac symptoms) were present. Treatment with sodium valproate was effective in curtailing insomnia. The wax and wane infradian modulation of the sleep length suggested the presence of a basic mechanism similar to the physical phenomenon of the "beats," i.e., a long period modulation of the amplitude of an oscillating system due to the interference of two uncoupled oscillators with a slightly different oscillation frequency. Hypothesizing a dysfunction of the circadian component of sleep, namely two uncoupled circadian cycles, a simple mathematical model estimated the difference of their periods of oscillation |34+/-2min| and reproduced the sleep-log data of the drug-free period of observation.Sleep Medicine 04/2010; 11(4):343-50. · 3.40 Impact Factor -
Article: REM-dreams recall in patients with narcolepsy-cataplexy.
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ABSTRACT: An abundant recall of dreams has been observed in clinical studies on patients with narcolepsy-cataplexy (NC), a neurological disorder characterized by an altered sleep architecture. Laboratory studies have shown that dream experiences developed during 1st-rapid eye movement (REM) sleep by NC patients are longer and more complex than those of healthy subjects. To establish whether these features indicate an earlier optimal functioning of the cognitive processes involved in dream generation rather than a more accurate dream recall, we compared the indicators of length and structural organization in reports of REM-dreams collected from 14 NC patients and their matched controls. During an experimental night two awakenings were provoked after 8 min in 1st- and 3rd-REM sleep; participants were asked to report their dream experience (spontaneous report) and then, if possible, further remembered parts of this experience (prompted report). All reports were analyzed using story-grammar rules, which allow us to identify units larger than single contents and describe their story-like organization. While dream recall (about 90%) was comparable in NC patients and controls, 1st-REM spontaneous reports were longer and more complex in NC patients, half of whom also provided prompted reports. After 3rd-REM awakening more than one third of NC patients and controls gave prompted reports, which were fairly comparable in length and complexity with the spontaneous reports. These findings confirm that the cognitive processes underlying dream generation reach their optimal functioning earlier in the night in NC patients than in normal subjects, and raises the question of whether the dream-stories described in spontaneous and prompted reports are part of the same or distinct REM-dreams.Brain research bulletin 11/2009; 81(1):133-40. · 2.18 Impact Factor -
Article: Sleep and time course of consolidation of visual discrimination skills in patients with narcolepsy-cataplexy.
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ABSTRACT: The level of procedural skills improves in normal individuals when the acquisition is followed by a period of sleep rather than wake. If sleep plays an important role in the consolidation process the advantage it provides should be reduced or delayed when its organization is altered, as in patients with chronic sleep disorders. To test this prediction in patients with narcolepsy-cataplexy (NC), who usually have a more fragmented organization of sleep than normals, we compared the initial, intermediate and delayed level of consolidation of visual skills. Twenty-two drug-naive NC patients and 22 individually-matched controls underwent training at a texture discrimination task (TDT) and were re-tested on the next morning (after a night spent in laboratory with polysomnography) and after another six nights (spent at home). TDT performance was worse in patients than controls at training and at both retrieval sessions and the time course of consolidation was different in NC patients (who improved mainly from next-day to 7th-day retrieval session) compared with controls. Moreover, the less-improving patients at next-day retrieval had a wider disorganization of sleep, probably because of an episode of rapid eye movement (REM) sleep at sleep onset REM, on post-training night more frequently than more-improving patients. These findings suggest that the time course of the consolidation process of procedural skills may be widely influenced by the characteristics of sleep organization (varying night-by-night much more in NC patients than controls) during post-training night.Journal of Sleep Research 04/2009; 18(2):209-20. · 3.16 Impact Factor -
Article: Story-like organization of REM-dreams in patients with narcolepsy-cataplexy.
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ABSTRACT: Narcolepsy with cataplexy (NC) is a neurological disorder characterized by excessive daytime sleepiness and an altered architecture of sleep. Previous laboratory studies have shown that frightening, bizarre and visually vivid contents are more frequent in dream experiences developed during the first period of REM sleep by NC patients than healthy subjects. As the structural organization of dream experiences of NC patients has not been yet examined, we compared its indicators in dream reports collected from a sample of NC patients and their matched controls. During an experimental night two awakenings were provoked after 8min of REM sleep in the first and third sleep cycle. Dream reports were analyzed using the rules of story grammars, capable of identifying units larger than single contents and describing their story-like organization. While dream recall (about 85%) was comparable in NC patients and controls, 1st-REM dream reports were longer in NC patients. Statistical analyses on the 12 NC patients and their matched controls who reported dreams after both REM periods showed that dream experiences occurring in 1st-REM reports of NC patients were longer and had a more complex organization than those of controls. These findings suggest that the cognitive processes underlying dream generation reach their optimal functioning earlier in the night in NC patients than in normal subjects.Brain research bulletin 09/2008; 77(4):206-13. · 2.18 Impact Factor -
Article: Cognitive functioning in chronic acquired hepatocerebral degeneration.
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ABSTRACT: CNS involvement is frequent in patients with chronic liver disease, resulting in overt or subclinical ("minimal") encephalopathy. Occasionally, patients liver cirrhosis may develop a progressive encephalopathy known as chronic acquired hepatocerebral degeneration (CAHD), presenting with neuropsychiatric changes and movement disorders. In patients affected by CAHD cognitive dysfunction is the rule, but to date this aspect has not been systematically studied. Our aim was to characterize the neuropsychological profile of cognitive impairment associated with CAHD. Eight patients with CAHD received extensive neuropsychological assessment, far from episodes of acute liver decompensation. Their cognitive performances were compared with those of 8 patients with cirrhosis free from CAHD or overt hepatic encephalopathy (HE) and with those of 8 healthy controls matched for age, sex and educational level. Patients with CAHD revealed a significant impairment of visuo-spatial attention compared to healthy controls, and a lower performance on a single task of visual search and sequencing when compared to cirrhotics without CAHD. Our findings support the hypothesis of a linear decline in attentional performances of patients with chronic liver disease, starting from cognitively intact patients, moving toward patients with minimal HE, and finally progressing to those with overt HE and CAHD.Metabolic Brain Disease 07/2008; 23(2):155-60. · 2.20 Impact Factor -
Article: Clinical, behavioural and polysomnographic correlates of cataplexy in patients with narcolepsy/cataplexy.
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ABSTRACT: Cataplexy is the main motor symptom of narcolepsy/cataplexy and is considered a form of rapid eye movement (REM) sleep motor dyscontrol appearing during wakefulness and elicited by emotions. This study examined the relationship between the frequency of cataplectic attacks in patients with narcolepsy/cataplexy and (a) the clinical and behavioural characteristics of cataplectic attacks, including the emotional tone of trigger events, and (b) the polysomnographic characteristics of daytime sleepiness, nocturnal sleep structure and indices of motor disorders during sleep. A consecutive series of 44 first-diagnosed drug-naive patients with narcolepsy/cataplexy, fulfilling the International Classification of Sleep Disorders, 2nd edition (ICSD-2) clinical and polysomnographic diagnostic criteria, were interviewed to estimate the frequency and clinical characteristics of cataplectic attacks and the occurrence of REM sleep behaviour disorder (RBD). All patients also underwent a video-polysomnographic recording to assess their sleep parameters and indices of altered motor control during sleep. Patients were divided into two groups on the basis of the frequency of cataplectic attacks, namely high-frequency (n=30) or low-frequency (n=14) depending on whether they estimated they had more or less than one attack per month. High-frequency patients (with a larger proportion of men) reported attacks more often affecting mainly the head, jaw and shoulder muscles and experienced more events among those listed as possible triggers of attacks. Sixty-one percent of patients reported RBD and 43% had an RBD episode at video-polysomnography regardless of the frequency of cataplectic attacks or gender. Lastly, the frequency of periodic leg movements (PLM) per hour was higher in men than women and increased with age. Patients with more than one cataplectic attack per month had more frequent involvement of head, jaw and shoulder muscles and were mainly men. The proportions of patients with clinically assessed RBD and an RBD episode documented by video-polysomnography, as well as conspicuous values of PLM per hour, are fairly consistent with those reported in recent small-group studies. Therefore, it seems legitimate to argue that RBD and PLM are nocturnal manifestations intrinsic to narcolepsy/cataplexy and that the gender-related differences in the frequency of attacks and the value of PLM per hour may be indicative of a larger difference in the clinical and polysomnographic characteristics of narcolepsy/cataplexy than hitherto suspected.Sleep Medicine 06/2008; 9(4):425-33. · 3.40 Impact Factor -
Article: Semantic priming effect during REM-sleep inertia in patients with narcolepsy.
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ABSTRACT: Patients with narcolepsy-cataplexy (NC) present excessive daytime sleepiness (EDS), cataplexy and an altered architecture of nocturnal sleep, with frequent episodes of REM-sleep at sleep onset (SOREM-sleep). This altered organization of nocturnal sleep may be accompanied by some differences in the functioning of the cognitive processes involved in the access, organization and consolidation of information during sleep. This study attempts to ascertain whether the activation of semantic memory during REM-sleep, as measured using a technique of semantic priming (namely, the facilitation of the activation of strongly-related rather than weakly-related and, overall, unrelated pairs of prime-target words) is different in NC patients compared to normal subjects. A lexical decision task (LDT) was carried out twice in wakefulness (at 10a.m. and after a 24h interval) and twice in the period of sleep inertia following awakening from SOREM and 4th-cycle REM-sleep on 12 NC patients and from 1st- and 4th-cycle REM-sleep on 12 matched controls. Reaction time (RT) to target words, taken as a measure of the semantic priming effect, proved to be longer (a) in NC patients than in control subjects; (b) in the period of REM-sleep inertia than in wakefulness; (c) in the first rather than the second session; and (d) for unrelated compared to weakly-related and, overall, strongly-related prime-target pairs. RT in post-REM-sleep sessions was less impaired, compared to waking sessions, and less dependent on the associative strength of prime-target pairs in NC patients than in normal subjects. Finally, RT of NC patients, although longer than that of normal subjects in waking sessions, significantly improved in the second session, as a consequence of either the amount of exercise or the consolidation advantage provided by REM-sleep for the procedural components of the task. The whole picture suggests a greater effectiveness of the activation of semantic memory during (SO)REM-sleep in NC patients rather than in normal subjects, and overall for the organization of new and unexpected relationships (such as those between unrelated pairs) between items of information.Brain Research Bulletin 01/2007; 71(1-3):270-8. · 2.82 Impact Factor -
Article: Functional focal retrograde amnesia: lost access to abstract autobiographical knowledge?
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ABSTRACT: We describe three patients exhibiting an acute reversible amnesia characterised by an impaired recollection of past events with preserved anterograde memory, thus consistent with a focal retrograde amnesia (FRA). This occurred after variable events: state of fugue, road accident, post-traumatic headache. Retrograde amnesia affected autobiographical memory so severely as to cover all of the patients' lives and to erase knowledge of their own identity. The retrieval of public events was variably affected, ranging from normality to severe impairment. No lesions were found on neuroimaging, and neurophysiological findings were unimpressive. FRA subsided in a few days, leaving a gap for the onset. The hypothesis of a psychogenic amnesia is considered, but overcoming the organic/psychogenic dichotomy the episodes appear as examples of "functional" memory inhibition, potentially triggered by different conditions, including events classifiable as psychic trauma. The clinical and neuropsychological traits of functional FRA are discussed. According to a current theory of autobiographical memory, the memory profile may be explained by a lost access to abstract autobiographical knowledge. Given some analogies with the more common transient global amnesia, a mechanism of spreading depression may also be hypothesised for functional FRA.Memory 11/2005; 13(7):690-9. · 2.09 Impact Factor -
Article: Distinguishing between clinical and minimal hepatic encephalopathy on the basis of specific cognitive impairment.
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ABSTRACT: It is well-known that liver cirrhosis is frequently accompanied by a wide range of neuropsychiatric abnormalities, including general and specific cognitive impairment. The aim of this study was to investigate which cognitive functions are selectively compromised in Hepatic Encephalopathy (HE) and to clarify the relationship between clinically overt or nonovert HE and the different forms and degrees of decay in cognitive deficits. Twenty-two patients without overt HE and 12 patients who showed overt HE at the first level of severity, along with matched control subjects, were compared in several cognitive domains. The results showed significant differences in some measures of attention between patients with minimal HE (mHE) and patients with overt HE. There were also notable differences in verbal short-term memory between patients with mHE and healthy subjects. Thus, we can hypothesize that there is a linear diminution in short-term memory and attentional performance starting from healthy patients, moving toward patients with mHE, and finally progressing toward patients with the first grade of overt HE. There are two types of diminution that we noted: between patients with mHE and the overt form, the decline in the attentional domain was more evident, while between healthy subjects and mHE patients, short-term memory showed a more evident decline.Metabolic Brain Disease 10/2005; 20(3):243-9. · 2.20 Impact Factor -
Article: Minimal hepatic encephalopathy: longitudinal effects of liver transplantation.
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ABSTRACT: The long-term effects of liver transplantation (LT) on minimal hepatic encephalopathy are poorly documented. To assess the cognitive performance of patients with cirrhosis and without overt encephalopathy, before and after LT. Longitudinal study comparing cognitive performance of patients with cirrhosis before LT and 6 to 18 months after LT, with matched control patients. University medical center. Six months after LT, patients had improved their performance in visuospatial and selective attention, visuospatial short-term and long-term memory, and language tasks. After 18 months, a further improvement was found for selective attention and verbal short-term memory, while no other cognitive functions varied over time. The present findings confirm preliminary studies showing that LT improves cognitive functions in patients with cirrhosis. The cognitive improvement is not generalized, but appears prominent in attention and memory and, once achieved, remains stable. Rates of recovery differ, being early for some functions and later for others.Archives of Neurology 03/2004; 61(2):242-7. · 7.58 Impact Factor -
Article: Continuity of the processing of declarative knowledge during human sleep: evidence from interrelated contents of mental sleep experiences.
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ABSTRACT: The positive influence of sleep on memory may partly depend on the processing which transforms items of declarative knowledge into contents of mental sleep experience (MSE). This view implies that the consolidation level should be more enhanced for those items which have been repeatedly processed and transformed into identical or very similar (so-called interrelated) contents of distinct MSEs in the same night. We examined here the occurrence of interrelated contents in the MSEs reported after an awakening provoked in stage 2 at sleep onset and the spontaneous awakening in the morning. Interrelated contents resulted much more frequently than the chance occurrence of contents with the same semantic features, regardless of the sleep stage in which morning awakening occurred. The accessibility of given items for transformation into MSE contents over the night makes it plausible that they are reprocessed, and thus further consolidated, during various stages and cycles of sleep.Neuroscience Letters 06/2003; 342(3):147-50. · 2.11 Impact Factor
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Institutions
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2004–2012
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University of Bologna
- Department of Experimental, Diagnostic and Specialty Medicine DIMES
Bologna, Emilia-Romagna, Italy
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2008
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Policlinico S.Orsola-Malpighi
Bologna, Emilia-Romagna, Italy
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