Roberto Bolzani

Different underlying neurocognitive deficits in developmental dyslexia: A comparative study

The aim of this study was to investigate the role of several specific neurocognitive functions in developmental dyslexia (DD). The performances of 60 dyslexic children and 65 age-matched normally reading children were compared on tests of phonological abilities, visual processing, selective and sustained attention, implicit learning, and executive functions. Results documented deficits in dyslexics on both phonological and non-phonological tasks. More stringently, in dyslexic children individual differences in non-phonological abilities accounted for 23.3% of unique variance in word reading and for 19.3% in non-word reading after controlling for age, IQ and phonological skills. These findings are in accordance with the hypothesis that DD is a multifactorial deficit and suggest that neurocognitive developmental dysfunctions in DD may not be limited to the linguistic brain area, but may involve a more multifocal cortical system.

Attentional engagement deficits in dyslexic children

Reading acquisition requires, in addition to appropriate phonological abilities, accurate and rapid selection of sublexical orthographic units by attentional letter string parsing. Spatio-temporal distribution of attentional engagement onto 3-pseudoletter strings was studied in 28 dyslexic and 55 normally reading children by measuring attentional masking (AM). AM refers to an impaired identification of the first of two sequentially presented masked objects (O1 and O2). In the present study, O1 was always centrally displayed, whereas the location of O2 (central or lateral) and the O1-O2 interval were manipulated. Dyslexic children showed a larger AM at the shortest O1-O2 interval and a sluggish AM recovery at the longest O1-O2 interval, as well as an abnormal lateral AM. More importantly, these spatio-temporal deficits of attentional engagement were selectively present in dyslexics with poor phonological decoding skills. Our results suggest that an inefficient spatio-temporal distribution of attentional engagement - probably linked to a parietal lobule dysfunction - might selectively impair the letter string parsing mechanism during phonological decoding.

The effect of on-line high-flux hemofiltration versus low-flux hemodialysis on mortality in chronic kidney failure: a small randomized controlled trial.

BACKGROUND Given the paucity of prospective randomized controlled trials assessing comparative performances of different dialysis techniques, we compared on-line high-flux hemofiltration (HF) with ultrapure low-flux hemodialysis (HD), assessing survival and morbidity in patients with end-stage renal disease (ESRD). STUDY DESIGN An investigator-driven, prospective, multicenter, 3-year-follow-up, centrally randomized study with no blinding and based on the intention-to-treat principle. SETTING & PARTICIPANTS Prevalent patients with ESRD (age, 16 to 80 years; vintage > 6 months) receiving renal replacement therapy at 20 Italian dialysis centers. INTERVENTIONS Patients were centrally randomly assigned to HD (n = 32) or HF (n = 32). OUTCOMES & MEASUREMENTS All-cause mortality, hospitalization rate for any cause, prevalence of dialysis hypotension, standard biochemical indexes, and nutritional status. Analyses were performed using the multivariate analysis of variance and Cox proportional hazard method. RESULTS There was significant improvement in survival with HF compared with HD (78%, HF versus 57%, HD) at 3 years of follow-up after allowing for the effects of age (P = 0.05). End-of-treatment Kt/V was significantly higher with HD (1.42 +/- 0.06 versus 1.07 +/- 0.06 with HF), whereas beta(2)-microglobulin levels remained constant in HD patients (33.90 +/- 2.94 mg/dL at baseline and 36.90 +/- 5.06 mg/dL at 3 years), but decreased significantly in HF patients (30.02 +/- 3.54 mg/dL at baseline versus 23.9 +/- 1.77 mg/dL; P < 0.05). The number of hospitalization events for each patient was not significantly different (2.36 +/- 0.41 versus 1.94 +/- 0.33 events), whereas length of stay proved to be significantly shorter in HF patients compared with HD patients (P < 0.001). End-of-treatment body mass index decreased in HD patients, but increased in HF patients. Throughout the study period, the difference in trends of intradialytic acute hypotension was statistically significant, with a clear decrease in HF (P = 0.03). LIMITATIONS This is a small preliminary intervention study with a high dropout rate and problematic generalizability. CONCLUSION On-line HF may improve survival independent of Kt/V in patients with ESRD, with a significant decrease in plasma beta(2)-microglobulin levels and increased body mass index. A larger study is required to confirm these results.

Effect of citicoline on visual acuity in amblyopia: preliminary results

Abstract•Background: Citicoline has been used to improve consciousness levels in cerebral trauma and as a complement for levodopa in Parkinsons disease. It has also been shown that severe glaucomatous visual field deficits improve for at least 4 months with the use of citicoline. In this paper, preliminary results are presented of an open and a double-blind study on the effect of citicoline in amblyopia.•Methods: The open study was started in 1991. Fifty patients with amblyopia were treated with citicoline (1000 mg i.m. daily for 15 days). They were selected from an age group beyond the plastic period of the visual system. Occlusion or other types of anti-amblyopic treatment were never used at the same time as citicoline. A double-blind study was conducted on 10 more patients, randomly assigned to a treatment or placebo group and followed for 6 months. A statistical test for repeated measures was performed on all the results.•Results: A statistically significant improvement in visual acuity was found both for the amblyopic and the sound eye in 46 of the 50 patients (92%). The behaviour was different for normal and amblyopic eyes. The improvement remained stable for at least 4 months. These results have been substantiated by the double-blind study. No side effects were observed.•Conclusion: Citicoline improves visual acuity, at least temporarily, in amblyopic patients beyond the plastic period of the visual system. Our results suggest that trials of citicoline as a medical treatment of amblyopia are warranted.

Coherence motion perception in developmental dyslexia: a meta‐analysis of behavioral studies

The magnitude of the association between developmental dyslexia (DD) and motion sensitivity is evaluated in 35 studies, which investigated coherence motion perception in DD. A first analysis is conducted on the differences between DD groups and age-matched control (C) groups. In a second analysis, the relationship between motion coherence threshold and reading ability is considered. Globally, the mean effect size (ES) is moderate (d = 0.675, 2334 subjects) with a large value (d = 0.747) for the between-groups differences in motion perception and a smaller mean ES (d = 0.178) for the correlational studies. The influence on ES of the stimuli parameters and subjects age is analyzed. The number of dots, the age of the subjects, and the type of analysis (i.e. between-group or correlational) are significantly related to the ES. Looking at the ES values, a smaller number of dots constituting the stimuli are associated with larger ES and, interestingly, the children studies are associated with lower ES in comparison with the researches evaluating adults. The large ES value supports the importance of studying motion perception deficits in DD groups, consistently with the claim that dorsal impairment/noise-exclusion deficit could be one of the risk factor of reading difficulties.

STORY-LIKE ORGANIZATION OF DREAM EXPERIENCE IN DIFFERENT PERIODS OF REM SLEEP

Four dream reports, collected from each of 16 subjects in an experimental night, were analysed using the criteria of Mandler and Johnsons story grammar. The experimental night was the first of the four nights where subjects had spontaneously given a dream report after each of the four awakenings planned in REM sleep. A multivariate analysis of covariance, taking the order of the nights where the experimental night occurred and the order of reports as factors, the number of stories per report as covariate and the number of statements in the setting, the number of statements in the event structure and number of episodes per story as dependent variables, showed that the greater length and complexity of reports collected in the second half of the night depends on a greater effectiveness of the dream production system rather than on a greater accuracy of recall. This increase concerns the organization of individual stories rather than the number of stories developed in a given time. These findings raise the issue of how dream production is re‐triggered during REM sleep. To cast light on this issue, it seems important to establish whether and how the themes of the various stories developed in a given dream experience are interrelated.

A Comparison Between the Magnetic Scleral Search Coil and Infrared Reflection Methods for Saccadic Eye Movement Analysis

BackgroundA non-invasive eye tracking system, based on pulsed infrared light (IR), was compared with the magnetic scleral search coil method (MSC) for saccadic eye movement recordings.MethodsTen normal subjects performed horizontal and vertical saccades recorded with both methods. Eight recordings were complete and analysed for maximum peak velocity (VMAX) and constant (C) of the main sequence curve.ResultsThe IR recordings showed significantly higher peak velocity values than the MSC system and generally more inter-individual variability. No significant difference regarding peak velocity was detected between abducting and adducting saccades or between upward and downward saccades with either of the systems. Horizontal saccades had higher peak velocities with both techniques.ConclusionsComparison of the main sequence plots of the IR and MSC eye tracking techniques reveals that the IR system yields higher values of maximum peak velocity and the constant, the differences being similar for eye movements in different directions. There are various possible explanations for the lower maximum velocity of the MSC recordings, e.g. slipping of the coil annulus on the surface of the eye and a change of the oculomotor command signal induced by wearing the coil. Also, artefacts associated with the IR recording system may cause overestimations of the saccadic velocity and, furthermore, contribute to the higher variability of the IR recordings.

Autonomic Reactivity during Viewing of an Unpleasant Film

The effect of an aversive, high-arousing film on heart rate, respiratory sinus arrhythmia, and electrogastrographic activity (EGG) was investigated. Previous studies have indicated a larger heart-rate deceleration for visual stimuli depicting surgery or blood compared to neutral content, and this phenomenon is similar to the bradycardia observed in animals in response to fear. The heart-rate deceleration is clearly parasympathetically driven, and it is considered a general index of attention. An accurate index of cardiac vagal tone can be obtained by means of quantification of the amplitude of respiratory sinus arrhythmia. The relationship between cardiac vagal tone and EGG is complex, but animal research has shown that suppressing vagal activity dampens gastric motility. We have investigated whether a movie depicting surgery is associated with greater heart-rate deceleration, larger increase in respiratory sinus arrhythmia, and greater increase in EGG activity compared to a neutral movie. In addition, if both respiratory sinus arrhythmia and EGG are indices of vagal tone, a positive correlation between these physiological responses was expected. Analysis indicated an effect of the surgery movie on heart rate and respiratory sinus arrhythmia, but not on EGG activity. Moreover, the expected correlation was not found. Implications for future studies are discussed.

Active processing of declarative knowledge during REM-sleep dreaming

The ability to process recently acquired knowledge is clearly maintained during sleep. Here we assess whether and how far the sleeper controls this processing (in a non‐volitional and non‐conscious manner). We posit that during sleep, the cognitive concerns of previous waking may guide access to, and processing of, items of declarative knowledge with which those concerns are associated. In a delayed recall task, before each of three sleep onsets in the same night, 12 subjects heard a different nonsense sentence. When awakened in rapid eye movement (REM) sleep, they were asked to report their dream experience and to recall the last sentence heard. Occurrences of incorporation into dream content were more frequent for this sentence than for the sentences heard before previous sleep onsets, and also more frequent than occurrences of similar contents in reports from a control night. However, the modalities of elaboration of dream contents did not vary. These findings indicate that cognitive concern can affect the accessing of recently acquired declarative knowledge during sleep, but not the modalities by which this is inserted into dream content. They also suggest that cognitive concern may help consolidate knowledge by increasing the likelihood of it being processed during sleep.

Dream structure in Parkinson's patients.

Dream reports of patients with Parkinsons disease (PD) were analyzed to ascertain whether cognitive deficits associated with this nonfocal brain pathology influence dream structure or dream recall. Fifteen outpatients with idiopathic PD were sampled (diagnosed from 1 to 10 years and currently in stage II or III of Hoehn and Yarhs scale); all were without psychiatric symptoms or major medical illnesses and were currently being treated with L-dopa. After an adaptation night in the sleep laboratory, each patient spent a night in which he/she was awakened at least twice in rapid eye movement sleep and asked to report dream experience. Thirteen patients were able to report at least one dream. Overall frequency of dream recall (71.4%) was fully compatible with normative data for the elderly. Multiple regression analyses showed that both the length of the dream report as story and the organization of contents into coherent episodes (analyzed using Mandler and Johnsons story grammar) varied significantly in relation to level of cognitive functioning and, in part, of language comprehension, but not in relation to age, illness duration, and dose of L-dopa.