A dedicated system for topographical working memory: evidence from domain-specific interference tests.

In the present study, we used single- and dual-task conditions to investigate the nature of topographical working memory to better understand what type of task can hamper performance during navigation. During dual-task conditions, we considered four different sources of interference: motor (M), spatial motor (SM), verbal (i.e. articulatory suppression AS) and spatial environmental (SE). In order to assess the nature of topographical working memory, we used the Walking Corsi Test, asking the participants to perform two tasks simultaneously (M, SM, AS and SE). Our results showed that only spatial-environmental interference hampers the execution of a topographical working memory task, suggesting a task-domain-specific effect. We also found general gender differences in the topographical working memory capabilities: men were more proficient than women, regardless of the type of interferences. However, like men, women performed worse when a spatial-environmental interference was present.

Environmental enrichment mitigates the effects of basal forebrain lesions on cognitive flexibility.

The aim of the present study was to investigate whether basal forebrain lesions were able to impair a task requiring cognitive flexibility abilities and analyzing the effect of the rearing in an enriched environment on such form of flexibility in rats with or without basal forebrain cholinergic lesions. In adult rats reared in enriched or standard conditions of the cholinergic projection to the neocortex damage was inflicted by 192 IgG-saporin injection into Ch4 region of basal forebrain. Their performance was compared with those of intact animals reared in analogous conditions in a four-choice serial learning task which taps flexibility in adapting to changing response rules. The results underlined the crucial role of the basal forebrain in mediating cognitive flexibility behaviors and revealed that the increase in social interactions, cognitive stimulation and physical activity of the rearing in enriched environment attenuated impairments caused by the cholinergic lesion. These findings demonstrate that rearing in an enriched environment can improve the ability to cope with brain damage suffered in adulthood.

Neural foundation of human moral reasoning: an ALE meta-analysis about the role of personal perspective.

Moral sense is defined as a feeling of the rightness or wrongness of an action that knowingly causes harm to people other than the agent. The large amount of data collected over the past decade allows drawing some definite conclusions about the neurobiological foundations of moral reasoning as well as a systematic investigation of methodological variables during fMRI studies. Here, we verified the existence of converging and consistent evidence in the current literature by means of a meta-analysis of fMRI studies of moral reasoning, using activation likelihood estimation meta-analysis. We also tested for a possible neural segregation as function of the perspective used during moral reasoning i.e., first or third person perspectives. Results demonstrate the existence of a wide network of areas underpinning moral reasoning, including orbitofrontal cortex, insula, amygdala, anterior cingulate cortex as well as precuneus and posterior cingulate cortex. Within this network we found a neural segregation as a function of the personal perspective, with 1PP eliciting higher activation in the bilateral insula and superior temporal gyrus as well as in the anterior cingulate cortex, lingual and fusiform gyri, middle temporal gyrus and precentral gyrus in the left hemisphere, and 3PP eliciting higher activation in the bilateral amygdala, the posterior cingulate cortex, insula and supramarginal gyrus in the left hemisphere as well as the medial and ventromedial prefrontal cortex in the right hemisphere. These results shed some more light on the contribution of these areas to moral reasoning, strongly supporting a functional specialization as a function of the perspective used during moral reasoning.

Where does brain neural activation in aesthetic responses to visual art occur? Meta-analytic evidence from neuroimaging studies.

Here we aimed at finding the neural correlates of the general aspect of visual aesthetic experience (VAE) and those more strictly correlated with the content of the artworks. We applied a general activation likelihood estimation (ALE) meta-analysis to 47 fMRI experiments described in 14 published studies. We also performed four separate ALE analyses in order to identify the neural substrates of reactions to specific categories of artworks, namely portraits, representation of real-world-visual-scenes, abstract paintings, and body sculptures. The general ALE revealed that VAE relies on a bilateral network of areas, and the individual ALE analyses revealed different maximal activation for the artworks' categories as function of their content. Specifically, different content-dependent areas of the ventral visual stream are involved in VAE, but a few additional brain areas are involved as well. Thus, aesthetic-related neural responses to art recruit widely distributed networks in both hemispheres including content-dependent brain areas of the ventral visual stream. Together, the results suggest that aesthetic responses are not independent of sensory, perceptual, and cognitive processes.

Electrical stimulation of the frontal cortex enhances slow-frequency EEG activity and sleepiness.

Our aim was to enhance the spontaneous slow-frequency EEG activity during the resting state using oscillating transcranial direct currents (tDCS) with a stimulation frequency that resembles the spontaneous oscillations of sleep onset. Accordingly, in this preliminary study, we assessed EEG after-effects of a frontal oscillatory tDCS with different frequency (0.8 vs. 5 Hz) and polarity (anodal, cathodal, and sham). Two single-blind experiments compared the after effects on the resting EEG of oscillatory tDCS [Exp. 1=0.8 Hz, 10 subjects (26.2 ± 2.5 years); Exp. 2=5 Hz, 10 subjects (27.4 ± 2.4 years)] by manipulating its polarity. EEG signals recorded (28 scalp derivations) before and after stimulation [slow oscillations (0.5-1 Hz), delta (1-4 Hz), theta (5-7 Hz), alpha (8-12 Hz), beta 1 (13-15 Hz) and beta 2 (16-24 Hz)] were compared between conditions as a function of polarity (anodal vs. cathodal vs. sham) and frequency of stimulation (0.8 vs. 5 Hz). We found a significant relative enhancement of the delta activity after the anodal tDCS at 5 Hz compared to that at 0.8 Hz. This increase, even though not reaching the statistical significance compared to sham, is concomitant to a significant increase of subjective sleepiness, as assessed by a visual analog scale. These two phenomena are linearly related with a regional specificity, correlations being restricted to cortical areas perifocal to the stimulation site. We have shown that a frontal oscillating anodal tDCS at 5 Hz results in an effective change of both subjective sleepiness and spontaneous slow-frequency EEG activity. These changes are critically associated to both stimulation polarity (anodal) and frequency (5 Hz). However, evidence of frequency-dependence seems more unequivocal than evidence of polarity-dependence.

Do you like Arcimboldo's? Esthetic appreciation modulates brain activity in solving perceptual ambiguity.

Esthetic experience is a unique, affectively colored, self-transcending subject-object relationship in which cognitive processing is felt to flow differently than during everyday experiences. Notwithstanding previous multidisciplinary investigations, how esthetic experience modulates perception is still obscure. We used Arcimboldo's ambiguous portraits to assess how the esthetic context organizes ambiguous percepts. The study was carried out using functional magnetic resonance imaging (fMRI) in healthy young volunteers (mean age 25.45; S.D. 4.51; 9 females), during both an explicit esthetic judgment task and an artwork/non-artwork classification task. We show that a distinct neural mechanism in the fusiform gyrus contributes to the esthetic experience of ambiguous portraits, according to the valence of the esthetic experience. Ambiguous artworks eliciting a negative esthetic experience lead to more pronounced activation of the fusiform face areas than ambiguous artworks eliciting a positive esthetic experience. We also found an interaction between task and ambiguity in the right superior parietal lobule. Taken together, our results demonstrate that a neural mechanism in the content-dependent brain regions of face processing underlies the esthetic experience of ambiguous portraits. Furthermore, they suggest that esthetic experience interacts with perceptual qualities of stimuli in the right superior parietal lobe, supporting the idea that esthetic experience arises from the interaction between top-down orienting of attention and bottom-up perceptual facilitation.

Event-related potentials and recognition memory within the 'levels of processing' framework.

Event-related potentials (ERPs) were recorded from nine subjects during an incidental memory paradigm. During the study phase subjects were engaged in two tasks requiring semantic and rhyming decisions. During the test phase, subjects were required to decide on each of 320 trials if the word was 'new' (never before presented) or 'old' (seen previously). Results showed that semantic old words were more often recognized than rhyming ones. ERPs to new words were more negative than ERPs to old words in the 400-800 latency range. ERPs to semantic old words were more positive than ERPs to rhyming ones in the same latency range. The difference between ERPs to semantic and rhyming old words confirms a relationship between ERPs and memory.

Upper/lower visual field asymmetry on a spatial relocation memory task.

The purpose of this study was to investigate whether the lower visual field advantage reported on a number of visual tasks depends on the activity of neural systems which process information from different spaces. To this end, a double dissociation logic was followed by observing the effects of visual and spatial interference on a relocation memory task performed by 80 volunteers. Results showed that participants were better at relocating stimuli presented in the lower than in the upper visual field. Moreover, a concurrent spatial task, but not a concurrent visual task, disrupted the visual field vertical asymmetry. Those findings confirm that the vertical asymmetry of visual field depends on the spatial processing of incoming stimuli.

Ultradian rhythms in the N1-P2 amplitude of the visual evoked potential in two inbred strains of mice: DBA/2J and C57BL/6.

Ultradian rhythmicity has been showed in many behavioural parameters in animals as well as in humans. We investigated the existence of a Basic Rest-Activity Cycle (BRAC) rhythm in amplitude fluctuations of mice's visual evoked potential (VEP) primary component. Two inbred strains of mice, C57BL/6 and DBA/2J, were used to verify the influence of genetics on biological rhythm as well. Results revealed the existence of an evident rhythm in the parameter under study and confirm previous reports of a 20 min. BRAC in avoidance behavior in DBA mice. This rhythm shows similar period within each strain, but significatively different periods between strains. Observed periods are near to species-specific reported BRAC cycle. Genetic hypothesys is suggested to explain differences between strains in expression of ultradian rhythm.

Slow eye movements and EEG power spectra during wake-sleep transition.

OBJECTIVE: The aim of the present study was to assess the relationship between slow eye movements (SEMs) and quantitative EEG measures during the wake-sleep transition. METHODS: Individual distributions were aligned with respect to the onset of stage 2 to provide an unequivocal hallmark of the beginning of sleep and to reduce the sources of variability in this transition. The relationship between EEG spectral powers and EOG changes was assessed by means of product-moment correlations and bootstrap analyses for individual time series, and by means of a multiple regression analysis for the entire sample. RESULTS: Results on the individual distributions as well as on averaged data showed a tight relationship between SEMs and EEG changes, negative across the 1-14 Hz frequency range and positive across the 15-30 Hz one. Spectral power in the sigma EEG band, that corresponds to the frequency at the phasic sleep spindles, resulted as the best predictor of SEM variations, being negatively correlated to the EOG changes. With respect to the other EEG frequency bands, the split half of the distributions with respect to stage 2 onset indicated a positive correlation of delta power with the increase of SEM activity before sleep onset, and of beta power with the decrease of SEMs after sleep onset. CONCLUSIONS: These results seem to suggest that sleep spindles could trigger the reduction and the final disappearance of slow eye movements in the late part of the wake-sleep transition.

Auditory evoked responses upon awakening from sleep in human subjects.

The hypothesis that a state of hypoarousal upon awakening should lead to a decrease in amplitude and an increase in latency of the N1-P2 components of the Auditory Evoked Potentials (AEPs) as compared to presleep wakefulness levels, was evaluated after two nocturnal awakenings and after the final morning awakening from a 7.5-h night of sleep. The amplitude of the N1-P2 complex was reduced upon awakening as compared to presleep wakefulness levels, but only following the first nocturnal awakening, scheduled after the first 2 h of sleep. This result is interpreted as indicating a link between slow wave sleep amount, mainly present during the first part of the night, and lowered levels of brain activation upon awakening. The reaction times, recorded concomitantly to AEPs, were more sensitive to the negative effects of sleep inertia.

Ultradian rhythms in avoidance behavior of DBA mice.

This study investigates ultradian rhythm in avoidance behavior of mice, which may constitute a basic rest activity cycle (BRAC). Reaction times (RTs) of an avoidance response to a visual warning stimulus that preceded an electric shock were measured by the use of a computer-controlled shuttle box. The male naive DBA mice were brought to a criterion of 98% correct responses in numerous training sessions. For each subject, all the temporal sequences of the RTs in the trials following achievement of the criterion were examined with discrete Fourier transform. Periodograms were obtained from three sessions for each of the two animals in the first experiment and from 15 subjects in the second experiment. Analysis of the periodograms reveals a stable rhythm in avoidance behavior of mice, with a period of about 14 min. The presence of these periodicities could show the existence, also in small rodents, of a BRAC rhythm.

Ultradian rhythms of reaction times in performance in vigilance tasks.

This study examined the presence of rhythmic fluctuations in vigilance tasks. The hypothesis was that individual attentional performance is subject to rhythmic variation beyond a linear decrease over time. In the first study the reaction times to an acoustic stimulus were recorded. The analysis of the individual periodograms indicated a rhythm in attentional capacity with periods ranging from 5 to 30 min. These findings indicate that considerable individual variation can be accounted for by considering individual periodicity in performance. Although marked individual differences between subjects are present, the rhythmic fluctuations are stable within each subject and between experimental sessions.

Event-related potentials and recognition memory: the effects of word imagery value.

Event-related potentials (ERPs) were recorded from 11 subjects during a recognition memory task. Subjects were auditorily presented with 160 target words and, after about 10 min, they were engaged in a recognition task. Subjects were required to determine on each of 320 trials if the word was 'new' (never before presented) or 'old' (heard previously). In the recognition test, 160 target words and 160 non-target words were used as stimuli. To assess the effect of word imagery value, 160 stimuli (80 target and 80 non-target) were high imagery words (HI) and the remaining 160 stimuli were low imagery words (LI). Word frequency was balanced across target and non-target words. Results showed that the old/new effect was reflected by a negative component (belonging to the N400 family, Cz maximum) which was larger for new words in the 400-700 ms range. The imagery effect was also present in the 250-550 ms range of the N400, which was larger for HI stimuli. The imagery effect was present at 400-550 ms only for target words. These results confirmed the hypothesis that negative components as N400, could reflect processes occurring during the memory retrieval of items.

[Experimental research on the effect of electro-acupuncture on reparative processes]. / Ricerche sperimentali sull'azione dell'elettroagopuntura nei processi riparativi.

With a view to clarifying the mechanism whereby electroacupuncture aids teh repair of trophic ulcers, including inveterate forms resistant to ordinary treatments, reference is made to histochemical findings and histological findings in periulcerous tissues and experimental research into wound healing. Preliminary work showed that electroacupuncture improves the blood supply to ulcerous tissue and the local biochemistry, and accelerates the repair process. Experimental work also made it clear that the method, when use on alternate days with the modalities employed in clinical practice, accelerates the healing of wounds in the experimental animal.

[Electro-acupuncture and trophic ulcer]. / Elettroagopuntura ed ulcere trofiche.

Electroacupuncture was used in the treatment of 50 cases of tropic ulcer of the lower extremities, including 34 following phlebitis, by stimulation with a Roccia VTM apparatus at voltages and frequencies up to the patient's tolerance threshold. The needles stimulation was maintained for a maximum of 7 hr. A cure was obtained in all cases, including those where the ulcers were inveterate and resistant to routine forms of management.

Why do you like Arcimboldo's portraits? Effect of perceptual style on aesthetic appreciation of ambiguous artworks.

Visual aesthetic experience reflects the states of the mind and the brain when visual artworks are being viewed. In the present study, we investigated whether perceptual style affects the aesthetic appreciation of ambiguous artworks, such as those of Arcimboldo, which are characterized by part-whole ambiguity. Participants were classified as having a global or local perceptual style and were asked to aesthetically judge two different types of artworks: portraits by Arcimboldo and by Renaissance painters. We found that perceptual style affected both the aesthetic appreciation and the degree of perceived ambiguity in Arcimboldo's artworks. Our findings suggest that aesthetic judgment is a consequence of the interaction between individual personal perceptual style and the perceptual features of artworks.

Resampling approach to statistical inference: bootstrapping from event-related potentials data.

We propose the use of the bootstrap resampling technique as a tool to assess the within-subject reliability of experimental modulation effects on event-related potentials (ERPs). The assessment of the within-subject reliability is relevant in all those cases when the subject score is obtained by some estimation procedure, such as averaging. In these cases, possible deviations from the assumptions on which the estimation procedure relies may lead to severely biased results and, consequently, to incorrect functional inferences. In this study, we applied bootstrap analysis to data from an experiment aimed at investigating the relationship between ERPs and memory processes. ERPs were recorded from two groups of subjects engaged in a recognition memory task. During the study phase, subjects in Group A were required to make an orthographic judgment on 160 visually presented words, whereas subjects in Group B were only required to pay attention to the words. During the test phase all subjects were presented with the 160 previously studied words along with 160 new words and were required to decide whether the current word was "old" or "new." To assess the effect of word imagery value, half of the words had a high imagery value and half a low imagery value. Analyses of variance performed on ERPs showed that an imagery-induced modulation of the old/new effect was evident only for subjects who were not engaged in the orthographic task during the study phase. This result supports the hypothesis that this modulation is due to some aspect of the recognition memory process and not to the stimulus encoding operations that occur during the recognition memory task. However, bootstrap analysis on the same data showed that the old/new effect on ERPs was not reliable for all the subjects. This result suggests that only a cautious inference can be made from these data.