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Sull’origine dei disturbi del sistema numerico approssimativo nei cerebrolesi destri.
No full textSecondo la definizione classica data da Heilman nel 1973, il neglect unilaterale è definito come l’incapacità di riferirsi, rispondere, od orientarsi verso
stimoli nuovi o significativi presentati nello spazio controlesionale. Questa
incapacità può interessare sia lo spazio fisico che immaginato.
Recentemente alcuni studi hanno suggerito che tale difficoltà possa estendersi anche allo spazio numerico, in particolare alla parte controlesionale della cosiddetta Linea Numerica Mentale (LNM). Il modello elaborato da Dehaene, propone infatti l’esistenza di una rappresentazione mentale numerica di tipo analogico, in cui i numeri sono rappresentati come porzioni di attivazione lungo una ipotetica linea mentale. Questo codice contiene informazioni sulla quantità rappresentate da simboli numerici e si assume
che tali rappresentazioni siano approssimative.
Lo scopo degli studi svolti è stato quello di indagare le caratteristiche del sistema numerico approssimativo in un campione di pazienti cerebrolesi destri.
In particolare negli studi del capitolo 3 è stata indagata la natura del bias di bisezione lungo la LNM, sia dal punto di vista fisiologico che anatomico.
L’ipotesi di un deficit di natura attenzionale è stata contrapposta a quella
relativa ad un deficit nella rappresentazione dei numeri piccoli. L’analisi svolta ci ha permesso di affrontare la questione se la LNM possieda un
orientamento sinistra-destra intrinseco. Nel capitolo 4 ci si è chiesti se il
deficit nella rappresentazione dei numeri piccoli sia un deficit di accesso in
presenza di una rappresentazione intatta o se il defict sia dovuto ad una
ipoattivazione della rappresentazione dei numeri piccoli nelle aree parietali
non danneggiate
The hemispheric distribution of α-band EEG activity during orienting of attention in patients with reduced awareness of the left side of space (spatial neglect)
Get PDFEEG studies in healthy humans have highlighted that alpha-band activity is relatively reduced over the occipital-parietal areas of the hemisphere contralateral to the direction of spatial attention. Here, we investigated the hemispheric distribution of alpha during orienting of attention in male and female right-brain-damaged patients with left spatial neglect. Temporal spectral evolution showed that in patients with neglect alpha oscillations over the damaged hemisphere were pathologically enhanced both during the baseline-fixation period that preceded cued orienting (capturing tonic alpha changes) and during orienting with leftward, rightward or neutral-bilateral spatial cues (reflecting phasic alpha changes). Patients without neglect showed a similar though significantly less enhanced hemispheric asymmetry. Healthy controls displayed a conventional decrease of alpha activity over the hemisphere contralateral to the direction of orienting. In right-brain-damaged patients, neglect severity in the line bisection task was significantly correlated both with tonic alpha asymmetry during the baseline period and with phasic asymmetries during orienting of attention with neutral-bilateral and leftward cues. Asymmetries with neutral-bilateral and leftward cues were correlated with lesion of white matter tracts linking frontal with parietal-occipital areas. These findings show that disruption of rostro-caudal white matter connectivity in the right hemisphere interferes with the maintenance of optimal baseline-tonic levels of alpha and the phasic modulation of alpha activity during shifts of attention. The hemispheric distribution of alpha activity can be used as a diagnostic tool for acquired pathological biases of spatial attention due to unilateral brain damage.SIGNIFICANCE STATEMENTAlpha desynchronization over the hemisphere contralateral to the attended side of space is a reliable marker of attentional orienting in the healthy human brain: can the same marker be used to spot and quantify acquired disturbances of spatial attention after unilateral brain injuries? Are pathological modifications in the hemispheric distribution of alpha specifically linked to attentional neglect for one side of space? We show that in patients with right brain damage the pathological enhancement of alpha oscillations over the parietal and occipital areas of the injured hemisphere is correlated with reduced awareness for the left side of space and with lesion of white matter pathways that subserve frontal modulation of alpha activity in posterior brain areas
Alexithymia and emotional reactions to odors
Get PDFAlexithymia is a psychological construct characterized by deficits in processing emotional stimuli. However, little is known about the processing of odours in alexithymia, even though there is extensive proof that emotion and olfaction are closely linked. The present study is aimed at investigating how alexithymic individuals process emotions conveyed by odors. Emotional responses to unpleasant, neutral odors and clean air were collected through self-report ratings and psychophysiological measures in a sample of 62 healthy participants with high (HA), medium (MA) and low (LA) levels of alexithymia. Moreover, participants performed tests on odors identification and threshold and completed questionnaires assessing olfactory imagery and awareness. Two main results have been found: first, HA and MA groups showed altered physiological responses to odors, compared to LA, while no differences among the groups were observed in odor ratings; and second, affective and cognitive alexithymia components were differently associated with the performance on olfactory tests, skin conductance response to odors, reaction times in the rating task, and scores on olfactory questionnaires. We conclude that alexithymia is characterized by altered physiological reactions to olfactory stimuli; moreover, we stress the importance of evaluating the different alexithymia components since they affect emotional stimuli processing in different ways
Emotional reactions in moral decision-making are influenced by empathy and alexithymia
No full textThe role of emotional processes in driving moral choices remains debated. In particular, diminished emotional processing and reduced empathy have been associated with unusual high rates of utilitarian responses in moral judgments while, to date, the effects of diminished emotional processing and empathy on moral decision-making have been only partially considered. In this study, we investigated the influence of empathy and alexithymia on behaviour and emotional responses while participants performed a moral decision task. Self-report (valence and arousal ratings) and physiological (skin conductance and heart rate) measures were collected during the task. Results showed that empathy and alexithymia shaped emotional reactions to moral decisions, but did not bias moral choices. The more empathic the participants, the more dilemmas were perceived as unpleasant and arousing, and the greater the increase in skin conductance. Conversely, alexithymia was characterized by a reduced physiological activation during moral decisions, but normal self-report ratings. Heart rate was not modulated by empathy or alexithymia. These results add new evidence to the field of moral decision showing that empathy and alexithymia modulate emotional reactions to moral decision
Food Inhibitory control and reward responsiveness in healthy ageing
Get PDFObjectives: Living in a complex food environment, humans face numerous decisions and choices every day. These decisions necessitate cognitive resources and the ability to balance metabolic needs with gratification. This study sought to examine whether ageing enhances responses to food stimuli due to reduced inhibitory control or reduces such responses due to a decline in the motivational system. Methods: Fifty young adults, aged 20-30 years, and 55 older adults, aged 65-91 years, without obesity, were recruited. Participants were asked to rate explicitly liking, wanting, and healthiness of both high- and low-calorie foods on a Likert scale. Additionally, they completed an affective priming task measuring affective reactions towards foods and a food go/no-go task to assess inhibitory control. Results: Older adults exhibit reduced food liking and wanting compared to young adults, but did not show increased impulsivity or implicit preference for high- and/or low-calorie foods. No significant relationship between perceived healthiness and reward responsiveness was observed in the older adult group. Discussion: Our findings suggest that healthy ageing is characterized by a diminished response to food due to low reward responsiveness. This is noteworthy, as the hedonic properties of foods are commonly believed to guide dietary choices. Understanding the relationship between age and food-related behaviour is crucial for developing targeted dietary interventions for older adults, which could enhance their overall health and quality of life
Small numbers in the right brain: Evidence from patients without and with spatial neglect
No full textFollowing seminal introspective evidence reported by Francis Galton (1880), several investigations have suggested that people with left-to-right reading habits, mentally organize numbers along the equivalent of a horizontal ruler, the mental number line (MNL), with small magnitudes located to the left of larger ones. Here we show that RBD suffer a specific impairment in the representation of the smallest number in the series of integers it is this representational deficit, rather than left spatial neglect, that provokes a bias toward higher numbers during the mental bisection of long 7- and 9-unit number interval
You stole my food! Eating alterations in frontotemporal dementia
No full textPatients with different types of dementia may exhibit pathological eating habits, including food fads, hyperphagia, or even ingestion of inanimate objects. Several findings reveal that such eating alterations are more common in patients with frontotemporal dementia (FTD) than other types of dementia. Moreover, eating alterations may differ between the two variants of the disease, namely the behavioral variant and semantic dementia (SD). In this review, we summarized evidences regarding four areas: eating and body weight alterations in FTD, the most common assessment methods, anatomical correlates of eating disorders, and finally, proposed underlying mechanisms. An increasing understanding of the factors that contribute to eating abnormalities may allow first, a better comprehension of the clinical features of the disease and second, shed light on the mechanism underlying eating behaviors in the normal population. © 2016 Informa UK Limited, trading as Taylor & Francis Group
Effects of tDCS on reward responsiveness and valuation in Parkinson's patients with impulse control disorders
Get PDF: Parkinson's disease (PD) patients with impulse control disorders (ICD) frequently report hypersensitivity to rewards. However, a few studies have explored the effectiveness of modulation techniques on symptoms experienced by these patients. In this study, we assessed the effect of anodal tDCS over the DLPFC on reward responsiveness and valuation in PD patients with ICD. 43 participants (15 PD patients with ICD, 13 PD without ICD, and 15 healthy matched controls) were asked to perform a reward-craving test employing both explicit (self-ratings of liking and wanting) and implicit (heart rate and skin conductance response) measures, as well as two temporal discounting tasks with food and money rewards. Each participant performed the experimental tasks during active anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC), anodal tDCS of the primary motor cortex (M1), and sham tDCS. Results showed increased wanting and a steeper temporal discounting of rewards in PD with ICD compared to the other groups. Moreover, we found that PD without ICD exhibit reduced liking for rewards. tDCS results capable to modulate the altered intensity of PD patients' liking, but not wanting and temporal discounting of rewards in PD patients with ICD. These findings confirm that alterations in reward responsiveness and valuation are characteristics of impulse control disorders in patients with PD but suggest that anodal tDCS over the left DLPFC is not capable to influence these processes. At the same time, they provide new insight into affective experience of rewards in PD
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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