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The aim of this study is the assessment of the applicability of the Form Coherence Test in a population of infants and adolescents. The Form Coherence Test is a computerized test for the evaluation of form perception ability. The subject is asked to discriminate a shape-stimulus among eight possible forms. The form perception is obtained by spatial coherent luminance dots visualized on a black background. Stimuli are presented in five levels of coherence which determines the difficulty of the task: starting from the 100% of coherence level, the number 1 of the coherently aligned dots exponentially decreases while the number of non-coherent dots (noise) increases. A sample of two hundred and fifty children (range 5-12 years) took part in the study. Accuracy is measured as the number of correct answers for each coherence level and for each stimulus. The Generalized Estimating Equation Model shows that the form perception accuracy decreased significantly in the subsequent coherence levels, starting from the 100% to 45%. The number of correct answers raised significantly with age. Age also affects the identification of the eight forms characterized by different difficulty. The results showed that Form Coherence Test is an instrument appropriate for the considered ages and allowed to evaluate the subject’s performance at different coherence level taking into account the age.

Recent research showed that a network of brain regions known as the Default Mode Network (DMN), including the ventromedial prefrontal cortex (vmPFC), is active when individuals remember the past, imagine the future, take the perspective of others, as well as during spontaneous cognition (mind wandering). The goal of this dissertation is to investigate whether the vmPFC plays a crucial role during DMN-related cognitive processes, such as MTT and mind wandering. Experiment 1 revealed that a damage to the vmPFC provokes the disruption of past and future MTT and a decreased ability to imagine future other-related episodes. vmPFC role extends to imagining events that are not self-relevant indicating that vmPFC is crucial for the imagination of complex experiences alternative to the current reality. In experiment 2, findings showed that a lesion to vmPFC disrupts the ability to construct complex atemporal scenarios. However, unlike the control groups, vmPFC patients had more difficulties in imagining future compared to fictitious experiences, suggesting that vmPFC is more critical for the simulation of future episodes. Experiment 3 revealed that these results are not explained by the disruption of non-episodic capabilities, such as narrative and working memory abilities. Furthermore, experiment 4 explored the effect of a lesion to vmPFC on the occurrence of mind wandering. A damage to the vmPFC provokes a decreased propensity to mind-wander, showing that vmPFC supports spontaneous cognition. Experiment 5 confirmed the involvement of the medial prefrontal cortex (mPFC) in supporting mind wandering. Using the transcranial direct current stimulation to inhibit the mPFC we could decrease the intensity of mind wandering in males. Together, these results point out the fundamental role of vmPFC in allowing human beings to escape the here and now, whether it occurs deliberately or spontaneously.

The present work aims at verifying the existence of such relations, focusing attention on the Behavioural Inhibition (BI) temperamental trait, recognised in literature as a risk factor for the development of social phobia in adolescence (Biederman et al., 2001; Rotge et al., 2011). The sample consists of 100 3 to 5 year old children and the teachers and parents. Direct measurements on the child were used to assess cognitive abilities (IQ and linguistic abilities) and the perceptions of teachers and parents, regarding child temperament and Behavioural Inhibition, were assessed and compared. The instruments used were the Behavioural Inhibition Questionnaire (Bishop et al., 2003), the Italian Questionnaires of Temperament (Axia, 2002), the Raven’s Coloured Progressive Matrices (Raven et al., 1998), two subscales from the Metaphonological Competences (Marotta et al., 2008), and the Non-Word Repetition (Vicari, 2008). The results suggest the parents and teachers have a significantly different perception of children, regarding certain temperamental dimensions. The teachers perceive the children as having a higher level of Behavioural Inhibition and Attention, compared to the perception of parents, while the former describe the children as having higher levels of Inhibition towards Novelty, Negative Emotionality and Motor Activity. Regarding cognitive abilities, children with a higher IQ are perceived as less inhibited towards noveltyby mothers and teachers. In summary, the difference in perception between parents and teachers could be hypothesised to be tied to the different observational context and to the different role, which might indicate a more complete perception of child temperament in teachers. Further research is needed to better study these aspects.

A new test of coherent form discrimination called Form Test is proposed in order to assess ventral stream functionality. The task consists of shape discrimination among 8 different forms. The form is obtained by a number white luminance coherent dots presented on a circular black background. Stimuli are presented in 5 levels of spatial coherence by increasing noise dots. Noise dots are non aligned and non coherent luminance dots which disturb shape discrimination. A sample of 163 children (75 females and 88 males, age range: 5-12) is considered. Results show significant differences among coherence levels: the number of correct answers decreases with noise increment. Moreover, the age of children affect the scores: the performance of children in Form Test improves with age. The results confirm that Form Test can be an helpful instrument to measure the ventral stream functionality and shows its sensitivity to the age differences.

We investigated episodic future thinking (EFT) and future-based cognition and decision-making in patient SG, who developed a dense retrograde amnesia following hypoxia due to a cardiac arrest. Despite intact general cognitive and executive functioning, SG was unable to remember events from his entire lifetime. He had, however, relatively spared anterograde memory and general semantic knowledge. Voxel-based morphometry detected a reduction of gray matter in the thalamus, cerebellum and fusiform gyrus bilaterally, and, at a reduced threshold, in several regions of the autobiographical memory network, including the hippocampi. We show that SG is unable to imagine personal future events, but can imagine fictitious events not self-relevant and not located in subjective time. Despite severely impaired EFT, SG shows normal attitudes towards the future time, and normal delay discounting rates. These findings suggest that retrieval of autobiographical information from long-term memory is necessary for EFT. However, relatively spared anterograde memory and general semantic knowledge may be sufficient to allow construction of fictitious experiences. As well, EFT is not necessary to drive future-oriented cognition and choice. These findings highlight the relation between autobiographical memory and EFT, and the fractionation of human temporal consciousness. Moreover, they contribute to our understanding of retrograde amnesia as an impairment of memory as well as future thinking.

Mind-wandering, the mind’s capacity to stray from external events and generate task-unrelated thought, has been associated with activity in the brain default network. To date, little is understood about the contribution of individual nodes of this network to mind-wandering. Here, we investigated the role of medial prefrontal cortex (mPFC) in mind-wandering, by perturbing this region with transcranial direct current stimulation (tDCS). Young healthy participants performed a choice reaction time task both before and after receiving cathodal tDCS over mPFC, and had their thoughts periodically sampled. We found that tDCS over mPFC - but not occipital or sham tDCS - decreased the propensity to mind-wander. The tDCS-induced reduction in mind-wandering occurred in men, but not in women, and was accompanied by a change in the content of task-unrelated though, which became more related to other people (as opposed to the self) following tDCS. These findings indicate that mPFC is crucial for mind-wandering, possibly by helping construction of self-relevant scenarios capable to divert attention inward, away from perceptual reality. Gender-related differences in tDCS-induced changes suggest that mPFC controls mind-wandering differently in men and women, which may depend on differences in the structural and functional organization of distributed brain networks governing mind-wandering, including mPFC.