Stefania De Vito

Episodic future thinking in amnesic mild cognitive impairment

Results from behavioral studies of amnesic patients and neuroimaging studies of individuals with intact memory suggest that a brain system involving direct contributions from the medial temporal lobes supports both remembering the past and imagining the future (Episodic Future Thinking). In the present study, we investigated whether amnesic Mild Cognitive Impairment (aMCI) affects EFT. Amnesic MCI is a high-risk factor for Alzheimers disease and is characterized by a selective impairment of episodic memory, likely reflecting hippocampal malfunctioning. The present study assessed, for the first time, whether the reduction of episodic specificity for past events, evident in aMCI patients, extends also to future events. We present data on 14 aMCI patients and 14 healthy controls, who mentally re-experienced and pre-experienced autobiographical episodes. Transcriptions were segmented into distinct details that were classified as either internal (episodic) or external (semantic). Results revealed that aMCI patients produced fewer episodic, event-specific details, and an increased number of semantic details for both past and future events, as compared to controls. These results are discussed with respect to the constructive episodic simulation hypothesis, which suggests that reminiscence and future thinking are the expression of the same neurocognitive system.

Future thinking in Parkinson's disease: an executive function?

Contrary to what was originally thought (Hassabis, Kumaran, Vann, & Maguire, 2007) recent data have shown that imagining the future is not entirely dependent on the hippocampus (Squire et al., 2010) and neuroimaging studies have demonstrated a frontopolar activation during future thinking tasks (Okuda et al., 2003). The present study investigated whether the performance of people with Parkinsons disease (PD) on future simulation tasks was dependent on memory or executive control. Thirty-one PD patients, asked to imagine possible future scenarios, generated fewer future episodic details than matched controls. The seven patients who clearly performed below the range of controls in future thinking, were also significantly poorer on the Frontal Assessment Battery (FAB), a battery assessing executive control, but showed no deficits in immediate or delayed memory tests. These results suggest that poor performance in the future thinking task is associated with poor executive control and less so with memory impairment. Flexible searching activities of past details might be crucial capacities for envisaging ones own future.

What differentiates episodic future thinking from complex scene imagery

We investigated the contributions of familiarity of setting, self-relevance and self-projection in time to episodic future thinking. The role of familiarity of setting was assessed, in Experiment 1, by comparing episodic future thoughts to autobiographical future events supposed to occur in unfamiliar settings. The role of self-relevance was assessed, in Experiment 2, by comparing episodic future thoughts to future events involving familiar others. The role of self-projection in time was assessed, in both Experiments, by comparing episodic future thoughts to autobiographical events that were not temporal in nature. Results indicated that episodic future thoughts were more clearly represented than autobiographical future events occurring in unfamiliar setting and future events involving familiar others. Our results also revealed that episodic future thoughts were indistinguishable from autobiographical atemporal events with respect to both subjective and objective detail ratings. These results suggest that future and atemporal events are mentally represented in a similar way.

Botallo's error, or the quandaries of the universality assumption

One of the founding principles of human cognitive neuroscience is the so-called universality assumption, the postulate that neurocognitive mechanisms do not show major differences among individuals. Without negating the importance of the universality assumption for the development of cognitive neuroscience, or the importance of single-case studies, here we aim at stressing the potential dangers of interpreting the pattern of performance of single patients as conclusive evidence concerning the architecture of the intact neurocognitive system. We take example from the case of Leonardo Botallo, an Italian surgeon of the Renaissance period, who claimed to have discovered a new anatomical structure of the adult human heart. Unfortunately, Botallos discovery was erroneous, because what he saw in the few samples he examined was in fact the anomalous persistence of a fetal structure. Botallos error is a reminder of the necessity to always strive for replication, despite the major hindrance of a publication system heavily biased towards novelty. In the present paper, we briefly discuss variations and anomalies in human brain anatomy and introduce the issue of variability in cognitive neuroscience. We then review some examples of the impact on cognition of individual variations in (1) brain structure, (2) brain functional organization and (3) brain damage. We finally discuss the importance and limits of single case studies in the neuroimaging era, outline potential ways to deal with individual variability, and draw some general conclusions.

Eye movements disrupt spatial but not visual mental imagery

Abstract It has long been known that eye movements are functionally involved in the generation and maintenance of mental images. Indeed, a number of studies demonstrated that voluntary eye movements interfere with mental imagery tasks (e.g., Laeng and Teodorescu in Cogn Sci 26:207–231, 2002). However, mental imagery is conceived as a multifarious cognitive function with at least two components, a spatial component and a visual component. The present study investigated the question of whether eye movements disrupt mental imagery in general or only its spatial component. We present data on healthy young adults, who performed visual and spatial imagery tasks concurrently with a smooth pursuit. In line with previous literature, results revealed that eye movements had a strong disruptive effect on spatial imagery. Moreover, we crucially demonstrated that eye movements had no disruptive effect when participants visualized the depictive aspects of an object. Therefore, we suggest that eye movements serve to a greater extent the spatial than the visual component of mental imagery.

Eye movements disrupt episodic future thinking

Remembering the past and imagining the future both rely on complex mental imagery. We considered the possibility that constructing a future scene might tap a component of mental imagery that is not as critical for remembering past scenes. Whereas visual imagery plays an important role in remembering the past, we predicted that spatial imagery plays a crucial role in imagining the future. For the purpose of teasing apart the different components underpinning scene construction in the two experiences of recalling episodic memories and shaping novel future events, we used a paradigm that might selectively affect one of these components (i.e., the spatial). Participants performed concurrent eye movements while remembering the past and imagining the future. These concurrent eye movements selectively interfere with spatial imagery, while sparing visual imagery. Eye movements prevented participants from imagining complex and detailed future scenes, but had no comparable effect on the recollection of past scenes. Similarities between remembering the past and imagining the future are coupled with some differences. The present findings uncover another fundamental divergence between the two processes.

Refusing to imagine? On the possibility of psychogenic aphantasia. A commentary on Zeman et al. (2015)

Our ability of “seeing” mental images in the absence of appropriate sensory input has always raised great interest not only in science, but also in philosophy (Sartre, 1940), art and literature (de Vito, 2012). Remarkably, however, some people claim not to experience visual mental images at all. Although the existence of these cases has been known to science for well over 100 years (Galton, 1880, 1883), the phenomenon has been oddly ignored and a systematic research is still lacking. Zeman, Dewar, and Della Sala (2015) provide important insights into several aspects of the lifelong inability to mentally visualize absent objects and label this condition “aphantasia”, a convenient term that may help focusing research on the phenomenon. The authors report on otherwise healthy people. However, this condition has been also observed in different populations of patients. Since Charcot (see Bartolomeo, 2008, for an English summary; Charcot & Bernard, 1883) neurologists have described cases of acquired inability to form visual mental images (review in Bartolomeo, 2002). However, it is worth noticing that in some of these cases, including the seminal Charcot case (Charcot& Bernard, 1883), an “abrupt and isolated” loss of visual imagery has been interpreted by some as having a psychogenic, rather than organic, origin (Zago et al., 2011). When considering evidence such as that reported by Zeman et al. (2015), it is important to keep this possibility in mind. Indeed, the case of imagery loss could engender an “organic/functional” debate analogous to the one that has revolved around retrograde amnesia (e.g., De Renzi, Lucchelli, Muggia, & Spinnler, 1997). Published in 1883 in Le Progr es M edical, the case of Monsieur X was presented as a sudden loss of the ability to construct mental images linked to a hypothetical circumscribed cerebral lesion and represents a classical citation in studies discussing the loss of visual imagery (e.g., Zeman et al., 2010). Although no evidence was available about the etiology or locus of the lesion (there was no post-mortem examination), left temporal damage sparing the occipital cortex might be hypothesized, given the described reading problems in the absence of elementary visual impairment (Bartolomeo, 2008). This hypothesis is consistent with neuropsychological and neuroimaging studies revealing that large networks of brain areas are engaged during visual mental imagery, probably reflecting top-down influences from frontal and parietal regions to the temporal lobe (e.g., Mechelli, Price, Friston, & Ishai, 2004). However, it is also important to consider that, at the onset of his imagery disorder, Monsieur X experienced something akin to mental alienation. Things around him appeared strange and new and he became anxious. As Monsieur X wrote to Charcot, “I observed a drastic change in my existence that obviously mirrored a remarkable change in my personality. Before I used to be emotional, enthusiastic with a prolific imagination; today I am calm, cold and I lost my imagination” (p. 570, own transl.). The Portuguese neurologist Ant onio de Sousa Magalh~ aes e Lemos (1906) observed a similar case of

Effects of self-generated versus experimenter-provided cues on the representation of future events.

Most experimental studies of prospection focused on episodic forms of future events prompted by means of verbal cues. However, there is evidence suggesting that future events differ considerably according to whether they are produced in response to external, experimenter-provided verbal cues or they are self-generated. In the present study, we compared the quality, the phenomenal characteristics, the temporal distribution, and the content of imagined events prompted by experimenter-provided cues (i.e., cue-words and short verbal sentences) or elicited by means of verbal cues that were self-generated in an autobiographical fluency task. The results showed that future events prompted by means of self-generated cues contained fewer event-specific details than future events prompted by experimenter-provided cues. However, future events elicited by means of self-generated and by experimenter-provided cues did not differ with respect to their phenomenal characteristics. The temporal distribution and the thematic content of future representations were also affected by the type of cue used to elicit prospection. These results offer a holistic view of the properties of future thinking and suggest that the content and the characteristics of envisioned future events may be affected by the method used to elicit prospection.

When brain damage "improves" perception: neglect patients can localize motion-shifted probes better than controls.

When we look at bars flashed against a moving background, we see them displaced in the direction of the upcoming motion (flash-grab illusion). It is still debated whether these motion-induced position shifts are low-level, reflexive consequences of stimulus motion or high-level compensation engaged only when the stimulus is tracked with attention. To investigate whether attention is a causal factor for this striking illusory position shift, we evaluated the flash-grab illusion in six patients with damaged attentional networks in the right hemisphere and signs of left visual neglect and six age-matched controls. With stimuli in the top, right, and bottom visual fields, neglect patients experienced the same amount of illusion as controls. However, patients showed no significant shift when the test was presented in their left hemifield, despite having equally precise judgments. Thus, paradoxically, neglect patients perceived the position of the flash more veridically in their neglected hemifield. These results suggest that impaired attentional processes can reduce the interaction between a moving background and a superimposed stationary flash, and indicate that attention is a critical factor in generating the illusory motion-induced shifts of location.

People believe each other to be selfish hedonic maximizers

Current computational models of theory of mind typically assume that humans believe each other to selfishly maximize utility, for a conception of utility that makes it indistinguishable from personal gains. We argue that this conception is at odds with established facts about human altruism, as well as the altruism that humans expect from each other. We report two experiments showing that people expect other agents to selfishly maximize their pleasure, even when these other agents behave altruistically. Accordingly, defining utility as pleasure permits us to reconcile the assumption that humans expect each other to selfishly maximize utility with the fact that humans expect each other to behave altruistically.