Carmelo Mario Vicario

Perceiving numbers alters time perception.

The representation of time, space and numbers are strictly linked in the primates cognitive system. Here we show that merely looking at number symbols biases a temporal judgment on their duration depending upon the numbers magnitude. In a first experiment, a group of healthy subjects was submitted to a time estimation task, requiring to judge whether the duration of a test stimulus was longer or shorter than that of a previous reference fixed stimulus (digit 5; duration 300 ms). Test stimuli were the digits 1, 5 and 9 ranging between 250 and 350 ms. The main results showed that temporal perception was biased according to the magnitude expressed by the digit: low digits (i.e. 1) leading to underestimation and high digits (i.e. 9) an overestimation of perceived duration. Control experiments showed that this result was consistent whatever digits were tested but not when letters of the alphabet were used. These findings argue for a functional interaction between time and numbers in the cognitive system.

Perceiving numbers affects the subjective temporal midpoint.

Temporal experience can be modulated by several environmental factors. There is increasing evidence that numerical quantity may also influence temporal processes. Here, it is shown that merely looking at numbers causes a bias in a time-bisection task that depends on its magnitude. In the first experiment, a group of healthy subjects was submitted to a time-bisection task in which numerical cues were blocked (blocked design). In the second experiment, a new group of participants performed a time-bisection task in which the previous numbers were all randomly arranged in the same block (intermingled design). Results show that temporal performance is biased when numbers of different magnitude are arranged in an intermingled design. These findings argue for a functional interaction between time and numbers, depending on the implicit extrapolation of the size difference between the displayed numbers rather than on the numerical size itself.

Temporal accuracy and variability in the left and right posterior parietal cortex

Several brain-imaging and lesion studies have suggested a role for the posterior parietal cortex (PPC) in computing interval-timing tasks. PPC also seems to have a key role in modulating visuospatial mechanisms, which are known to affect temporal performance. By applying transcranial direct current stimulation (tDCS) over the left and right PPC, we aimed to modulate timing ability performance in healthy humans performing a cognitively controlled timing task. In two separate experiments we compared time-processing abilities of two groups of healthy adults submitted to anodal, cathodal or sham tDCS over right or left PPC, by employing a supra-second time reproduction task. Cathodal stimulation over the right PPC affected temporal accuracy by leading participants to overestimate time intervals. Moreover, when applied to the left PPC, it reduced variability in reproducing temporal intervals. No effect was reported for anodal stimulation. These results expand current knowledge on the role of the parietal cortex on temporal processing. We provide evidence that the parietal cortex of both hemispheres is involved in temporal processing by acting on distinct components of timing performance such as accuracy and variability.

Temporal Abnormalities in Children With Developmental Dyscalculia

Recent imaging studies have associated Developmental dyscalculia (DD) to structural and functional alterations corresponding Parietal and the Prefrontal cortex (PFC). Since these areas were shown also to be involved in timing abilities, we hypothesized that time processing is abnormal in DD. We compared time processing abilities between 10 children with pure DD (8 years old) and 11 age-matched healthy children. Results show that the DD group underestimated duration of a sub-second scale when asked to perform a time comparison task. The timing abnormality observed in our DD participants is consistent with evidence of a shared fronto-parietal neural network for representing time and quantity.

Non-invasive brain stimulation for the treatment of brain diseases in childhood and adolescence: state of the art, current limits and future challenges

In the last decades interest in application of non-invasive brain stimulation for enhancing neural functions is growing continuously. However, the use of such techniques in pediatric populations remains rather limited and mainly confined to the treatment of severe neurological and psychiatric diseases. In this article we provide a complete review of non-invasive brain stimulation studies conducted in pediatric populations. We also provide a brief discussion about the current limitations and future directions in a field of research still very young and full of issues to be explored.

Left Hand Dominance Affects Supra-Second Time Processing

Previous studies exploring specific brain functions of left- and right-handed subjects have shown variances in spatial and motor abilities that might be explained according to consistent structural and functional differences. Given the role of both spatial and motor information in the processing of temporal intervals, we designed a study aimed at investigating timing abilities in left-handed subjects. To this purpose both left- and right-handed subjects were asked to perform a time reproduction of sub-second vs. supra-second time intervals with their left and right hand. Our results show that during processing of the supra-second intervals left-handed participants sub-estimated the duration of the intervals, independently of the hand used to perform the task, while no differences were reported for the sub-second intervals. These results are discussed on the basis of recent findings on supra-second motor timing, as well as emerging evidence that suggests a linear representation of time with a left-to-right displacement.

Timing Flickers across Sensory Modalities

In tasks requiring a comparison of the duration of a reference and a test visual cue, the spatial position of test cue is likely to be implicitly coded, providing a form of a congruency effect or introducing a response bias according to the environmental scale or its vectorial reference. The precise mechanism generating these perceptual shifts in subjective duration is not understood, although several studies suggest that spatial attentional factors may play a critical role. Here we use a duration comparison task within and across sensory modalities to examine if temporal performance is also modulated when people are exposed to spatial distractors involving different sensory modalities. Different groups of healthy participants performed duration comparison tasks in separate sessions: a time comparison task of visual stimuli during exposure to spatially presented auditory distractors; and a time comparison task of auditory stimuli during exposure to spatially presented visual distractors. We found the duration of visual stimuli biased depending on the spatial position of auditory distractors. Observers underestimated the duration of stimuli presented in the left spatial field, while there was an overestimation trend in estimating the duration of stimuli presented in the right spatial field. In contrast, timing of auditory stimuli was unaffected by exposure to visual distractors. These results support the existence of multisensory interactions between space and time showing that, in cross-modal paradigms, the presence of auditory distractors can modify visuo-temporal perception but not vice versa. This asymmetry is discussed in terms of sensory–perceptual differences between the two systems.

Lateral Head Turning Affects Temporal Memory

Spatial attention is a key factor in the exploration and processing of the surrounding environment, and plays a role in linking magnitudes such as space, time, and numbers. The present work evaluates whether shifting the coordinates of spatial attention through rotational head movements may affect the ability to estimate the duration of different time intervals. A computer-based implicit timing task was employed, in which participants were asked to concentrate and report verbally on colour changes of sequential stimuli displayed on a computer screen; subsequently, they were required to reproduce the temporal duration (ranging between 5 and 80 sec.) of the perceived stimuli using the computer keyboard. There was statistically significant overestimation of the 80-sec. intervals exclusively on the rightward rotation head posture, whereas head posture did not affect timing performances on shorter intervals. These findings support the hypothesis that the coordinates of spatial attention influence the ability to process time, consistent with the existence of common cortical metrics of space and time in healthy humans.

The neurophysiology of magnitude: One example of extraction analogies

Abstract Brain mapping for analogical information seems based on extraction of similarity on various levels, including perceptual similarity, abstract conceptual dimensions, and goals. Given the utility of analogical inferences on quantities that would extract covariance of time, space, and numbers, we discuss here the processing of time, space, and quantity as an example of the process of extraction of analogical information. This view is supported by evidence documenting common activation of the prefrontal cortex (PFC) in the processing of all of these magnitudes.

Core, social and moral disgust are bounded: A review on behavioral and neural bases of repugnance in clinical disorders

HIGHLIGHTSWe review the relationship between core, social and moral disgust in clinical models.Abnormal insula activity affects all the three domains of disgust processing.5‐HT alterations predict core and moral disgust in clinical models. ABSTRACT Disgust is a multifaceted experience that might affect several aspects of life. Here, we reviewed research on neurological and psychiatric disorders that are characterized by abnormal disgust processing to test the hypothesis of a shared neurocognitive architecture in the representation of three disgust domains: i) personal experience of ‘core disgust’; ii) social disgust, i.e., sensitivity to others’ expressions of disgust; iii) moral disgust, i.e., sensitivity to ethical violations. Our review provides some support to the shared neurocognitive hypothesis and suggests that the insula might be the “hub” structure linking the three domains of disgust sensitivity, while other brain regions may subserve specific facets of the multidimensional experience. Our review also suggests a role of serotonin core and moral disgust, supporting “neo‐sentimentalist” theories of morality, which posit a causal role of affect in moral judgment.