Mariagrazia Benassi

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.

Personality characteristics and psychological distress associated with primary exercise dependence: An exploratory study

The aim of this study was to assess personality characteristics and psychological distress associated with primary exercise dependence (ExeDepI) in a mixed gender sample. A cross-sectional study was carried out with adult habitual physical exercisers. A total of 79 participants voluntarily completed a package of self-report questionnaires including the Exercise Dependence Questionnaire (EDQ), the Eating Disorder Inventory II (EDI-2), the Temperament and Character Inventory (TCI), the Attitude Toward Self scale (ATS), and the Symptom Questionnaire (SQ). Significant differences were found on the EDQ exercise for weight control subscale with regard to gender, as well as on the EDI-2 total score and five of its subscales, with higher scores for females compared to males. Participants reporting primary exercise dependence (N=32) were more likely to present with disordered eating patterns than controls (N=47). They also showed higher levels of harm avoidance and persistence on the TCI, but lower self-directness and less mature character. Furthermore, ExeDepI group scored higher on the ATS dysmorphophobia subscale, as well as on the anxiety and hostility subscales of the SQ compared to the control group. These findings provide support to the idea that primary exercise dependence can be considered as a clinical syndrome associated with certain personality characteristics and psychological symptoms that might be accurately assessed in clinical settings.

Bodily self: an implicit knowledge of what is explicitly unknown

We tested the hypothesis that the body self-advantage, i.e., the facilitation in discriminating self versus other people’s body-effectors, is the expression of an implicit and body-specific knowledge, based mainly on the sensorimotor representation of one’s own body-effectors. Alternatively, the body self-advantage could rely on visual recognition of pictorial cues. According to the first hypothesis, using gray-scale pictures of body-parts, the body self-advantage should emerge when self-body recognition is implicitly required and should be specific for body-effectors and not for inanimate-objects. In contrast, if the self-advantage is due to a mere visual–perceptual facilitation, it should be independent of the implicit or explicit request (and could be extended also to objects). To disentangle these hypotheses, healthy participants were implicitly or explicitly required to recognize either their own body-effectors or inanimate-objects. Participants were more accurate in the implicit task with self rather than with others’ body-effectors. In contrast, the self-advantage was not found when an explicit recognition of one’s own body-effectors was required, suggesting that the body self-advantage relies upon a sensorimotor, rather than a mere visual representation of one’s own body. Moreover, the absence of both self/other and implicit/explicit effects, when processing inanimate-objects, underlines the differences between the body and other objects.

Isometric force measured in human horizontal eye muscles attached to or detached from the globe

BackgroundHuman eye muscle tension has been measured directly only in detached condition. The purpose of this study is to compare force development in single, horizontal human eye muscle during saccadic eye movements, first when the muscle was still attached and later when it was detached from the globe.MethodsEleven horizontal muscles of eight patients were examined during surgery under topical anesthesia for concomitant strabismus. None of the muscles examined had been operated before. Isometric muscle tension was recorded with a strain gauge system, to which the muscle tendon was attached by a silk suture. The subjects made saccadic eye movements with the non-recorded eye by fixating light-emitting diodes in the center and at 10, 20, and 30° horizontally to each side. Continuous and stepwise saccades were produced. In the tension signals, peak tension (Fp), steady tension (Fs), and the ratio Fp/Fs were measured. Statistical analysis was done with multivariate analysis of variance.ResultsThe values of Fp, Fs, and Fp/Fs at different amplitudes of the saccadic eye movements were compared in the attached and the detached muscle. There were no consistent statistical differences between the values obtained in the two conditions.ConclusionsThe muscle force development, measured at the tendon, was the same in muscles attached to the globe and in muscles free from the globe. Thus isometric muscle tension can be adequately recorded in muscles still attached to the globe, which increases the possibilities for studying contractile properties of various eye muscles during ophthalmic surgery procedures performed under topical anesthesia.

Motion perception in children with foetal alcohol syndrome

Aim:  To evaluate the visual magnocellular pathway by a coherent motion perception test in children with foetal alcohol syndrome (FAS).

Isometric force development in human horizontal eye muscles and pulleys during saccadic eye movements.

Purpose:  The connective tissue elements forming the check ligaments and portals of the human eye muscles have recently been ascribed with a pulley function. Active positioning of the pulleys over orbital layer contraction during eye movements has been suggested. Other studies have instead demonstrated fibrous tissue connections between all parts of the muscle and the pulleys. We aimed to compare the isometric force developed at the muscle tendon and at the pulleys of the horizontal eye muscles, and to investigate which eye muscle structures might exert force on the pulleys.

Visual recognition time in strabismus: small-angle versus large-angle deviation.

Purpose To measure the possible differences in monocular detection time of a threshold visual acuity stimulus (recognition time [RT]) between patients with small-angle and large-angle strabismus. METHODS Ten patients with free alternating esotropia were tested (10 to 18 years old): five with small-angle esotropia (≤7°), five with large-angle esotropia (15° to 20°). Six age-matched normal subjects served as controls. The RT of the threshold stimulus was measured in both eyes sequentially for stimuli presented in the center of a computer monitor (RT 1). Moreover, we measured the time necessary for identifying the same threshold visual acuity stimulus generated on the computer screen in the moment in which fixation is taken up by one eye after occlusion of the second eye (RT 2). Using the same setting, RT was also measured monocularly in all strabismic and normal subjects who were originally looking at a luminous fixation point positioned horizontally at 6.5 and 15 degrees from the center of the monitor (RT 3). Results The multivariate analysis of variance for repeated measures indicated that there was no statistical difference in RT 1 between groups. The mean RT2 was significantly longer (p<0.001) in large-angle strabismic eyes when compared with that of normal control eyes. The mean RT 2 in small-angle strabismic eyes did not differ significantly from that of normal eyes. Finally, RT 3 (both at 6.5° and 15° of eccentricity) did not show any significant difference in the three different study groups. CONCLUSIONS The authors hypothesized that alternating strabismus patients may have a significant advantage in maintaining a small-angle deviation, as a large-angle deviation would require longer RT in the moment the deviated eye takes up fixation. It can be speculated that the extension of re-fixation movement, obviously shorter in small-angle strabismus patients, is the main factor responsible for longer RT occurring in large-angle strabismus patients.

A New Way to Find the Primary Position in Three-Dimensional Measurements

The eye can rotate around an infinite number of axes, all but one located within Listing’s plane, which in most instances corresponds to the equatorial plane. Listing’s plane is thus perpendicular to the visual axes when the eyes are in primary position. Ocular torsion occurs around an axis parallel to the line of sight and corresponds to the angle between eye vertical axis and the objective vertical direction in Fick’s coordinates. The ocular torsion in tertiary positions can be explained by using Listing’s law. Listing’s law is valid for saccadic and smooth pursuit movements, but it can be violated by vestibular eye movements like head rotations in roll. In these cases the real primary position (PP) coordinates are required to evaluate the theoretical torsion from the Listing’s law and to compare the theoretical to the measured torsion values. For torsion we need to refer the measured angle to the PP, as defined by Listing’s law, from which pure horizontal and vertical movements do not produce any torsional change. Many methods have been proposed to evaluate the PP. The aim of this work has been to set up and test a new method for the evaluation of the PP based on two-dimensional fitting curves.

Changes of saccadic eye movements in thyroid‐associated ophthalmopathy

Purpose:  To establish whether or not the dynamics of saccadic eye movements are significantly changed in patients with different stages of thyroid‐associated ophthalmopathy (TAO) and, subsequently, if analysis of saccades could serve as an additional diagnostic tool for early detection of inflammatory activity in TAO.