Alexithymia and emotional reactions to odors

Alexithymia 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

Food knowledge depends upon the integrity of both sensory and functional properties: a VBM, TBSS and DTI tractography study

Food constitutes a fuel of life for human beings. It is therefore of chief importance that their recognition system readily identifies the most relevant properties of food by drawing on semantic memory. One of the most relevant properties to be considered is the level of processing impressed by humans on food. We hypothesized that recognition of raw food capitalizes on sensory properties and that of transformed food on functional properties, consistently with the hypothesis of a sensory-functional organization of semantic knowledge. To test this hypothesis, patients with Alzheimer's disease, frontotemporal dementia, primary progressive aphasia, and healthy controls performed lexical-semantic tasks with food (raw and transformed) and non-food (living and nonliving) stimuli. Correlations between task performance and local grey matter concentration (VBM) and white matter fractional anisotropy (TBSS) led to two main findings. First, recognition of raw food and living things implicated occipital cortices, typically involved in processing sensory information and, second, recognition of processed food and nonliving things implicated the middle temporal gyrus and surrounding white matter tracts, regions that have been associated with functional properties. In conclusion, the present study confirms and extends the hypothesis of a sensory and a functional organization of semantic knowledge

No inherent left and right side in human ‘mental number line': evidence from right brain damage

Spatial reasoning has a relevant role in mathematics and helps daily computational activities. It is widely assumed that in cultures with left-to-right reading, numbers are organized along the mental equivalent of a ruler, the mental number line, with small magnitudes located to the left of larger ones. Patients with right brain damage can disregard smaller numbers while mentally setting the midpoint of number intervals. This has been interpreted as a sign of spatial neglect for numbers on the left side of the mental number line and taken as a strong argument for the intrinsic left-to-right organization of the mental number line. Here, we put forward the understanding of this cognitive disability by discovering that patients with right brain damage disregard smaller numbers both when these are mapped on the left side of the mental number line and on the right side of an imagined clock face. This shows that the right hemisphere supports the representation of small numerical magnitudes independently from their mapping on the left or the right side of a spatial-mental layout. In addition, the study of the anatomical correlates through voxel-based lesion-symptom mapping and the mapping of lesion peaks on the diffusion tensor imaging-based reconstruction of white matter pathways showed that the rightward bias in the imagined clock-face was correlated with lesions of high-level middle temporal visual areas that code stimuli in object-centred spatial coordinates, i.e. stimuli that, like a clock face, have an inherent left and right side. In contrast, bias towards higher numbers on the mental number line was linked to white matter damage in the frontal component of the parietal-frontal number network. These anatomical findings show that the human brain does not represent the mental number line as an object with an inherent left and right side. We conclude that the bias towards higher numbers in the mental bisection of number intervals does not depend on left side spatial, imagery or object-centred neglect and that it rather depends on disruption of an abstract non-spatial representation of small numerical magnitude

Sull’origine dei disturbi del sistema numerico approssimativo nei cerebrolesi destri.

Secondo 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

Sull’origine dei disturbi del sistema numerico approssimativo nei cerebrolesi destri.

Secondo 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

How experience modulates semantic memory for food: Evidence from elderly adults and centenarians

In order to make sense of the objects we encounter in everyday life we largely rely on previous knowledge stored in our semantic memory. Semantic memory is considered dependent on lifelong experience and cultural knowledge. So far, a few studies have investigated the role of expertise on the organization of semantic memory, whereas life-long experience has largely been overlooked. In this study, we investigated this issue using food concepts. In particular, we administered different semantic tasks using food (natural and transformed) and non-food (living and non-living things) as stimuli to participants belonging to three different age cohorts (56–74, 75–91, 100–108), who were also asked to report on the dietary habits held throughout their life. In addition, we investigated to what extent psycholinguistic variables influence the semantic performance of different age cohorts. Results showed that Centenarians recognized natural food better than transformed food, while the other two groups showed the opposite pattern. According to our analyses, experience is responsible for this effect in Centenarians, as their dietary habits seem to suggest. Moreover, significant correlations between picture naming and age of acquisition, familiarity and frequency were observed. This study indicates that lifelong experience can shape conceptual knowledge of food concepts, and that semantic memory is less resilient to aging than initially thought

Emotional reactions in moral decision-making are influenced by empathy and alexithymia

The 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

The hemispheric distribution of \u3b1-band EEG activity during orienting of attention in patients with reduced awareness of the left side of space (spatial neglect)

EEG 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