Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 40
Filtrar
Más filtros

Banco de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Neuropsychol Rev ; 2024 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-38319529

RESUMEN

Semantic interference (SI) and phonological facilitation (PF) effects occur when multiple representations are co-activated simultaneously in complex naming paradigms, manipulating the context in which word production is set. Although the behavioral consequences of these psycholinguistic effects are well-known, the involved brain structures are still controversial. This paper aims to provide a systematic review and a coordinate-based meta-analysis of the available functional neuroimaging studies investigating SI and PF in picture naming paradigms. The included studies were fMRI experiments on healthy subjects, employing paradigms in which co-activations of representations were obtained by manipulating the naming context using semantically or phonologically related items. We examined the principal methodological aspects of the included studies, emphasizing the existing commonalities and discrepancies across single investigations. We then performed an exploratory coordinate-based meta-analysis of the reported activation peaks of neural response related to SI and PF. Our results consolidated previous findings regarding the involvement of the left inferior frontal gyrus and the left middle temporal gyrus in SI and brought out the role of bilateral inferior parietal regions in PF.

2.
Neuroimage ; 277: 120242, 2023 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-37348625

RESUMEN

The extensive use of transcranial direct current stimulation (tDCS) in experimental and clinical settings does not correspond to an in-depth understanding of its underlying neurophysiological mechanisms. In previous studies, we employed an integrated system of Transcranial Magnetic Stimulation and Electroencephalography (TMS-EEG) to track the effect of tDCS on cortical excitability. At rest, anodal tDCS (a-tDCS) over the right Posterior Parietal Cortex (rPPC) elicits a widespread increase in cortical excitability. In contrast, cathodal tDCS (c-tDCS) fails to modulate cortical excitability, being indistinguishable from sham stimulation. Here we investigated whether an endogenous task-induced activation during stimulation might change this pattern, improving c-tDCS effectiveness in modulating cortical excitability. In Experiment 1, we tested whether performance in a Visuospatial Working Memory Task (VWMT) and a modified Posner Cueing Task (mPCT), involving rPPC, could be modulated by c-tDCS. Thirty-eight participants were involved in a two-session experiment receiving either c-tDCS or sham during tasks execution. In Experiment 2, we recruited sixteen novel participants who performed the same paradigm but underwent TMS-EEG recordings pre- and 10 min post- sham stimulation and c-tDCS. Behavioral results showed that c-tDCS significantly modulated mPCT performance compared to sham. At a neurophysiological level, c-tDCS significantly reduced cortical excitability in a frontoparietal network likely involved in task execution. Taken together, our results provide evidence of the state dependence of c-tDCS in modulating cortical excitability effectively. The conceptual and applicative implications are discussed.


Asunto(s)
Excitabilidad Cortical , Estimulación Transcraneal de Corriente Directa , Humanos , Estimulación Transcraneal de Corriente Directa/métodos , Estimulación Magnética Transcraneal/métodos , Electroencefalografía , Lóbulo Parietal/fisiología , Potenciales Evocados Motores/fisiología
3.
J Psychiatry Neurosci ; 46(6): E592-E614, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34753789

RESUMEN

BACKGROUND: The possibility of using noninvasive brain stimulation to treat mental disorders has received considerable attention recently. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are considered to be effective treatments for depressive symptoms. However, no treatment recommendation is currently available for anxiety disorders, suggesting that evidence is still limited. We conducted a systematic review of the literature and a quantitative analysis of the effectiveness of rTMS and tDCS in the treatment of anxiety disorders. METHODS: Following PRISMA guidelines, we screened 3 electronic databases up to the end of February 2020 for English-language, peer-reviewed articles that included the following: a clinical sample of patients with an anxiety disorder, the use of a noninvasive brain stimulation technique, the inclusion of a control condition, and pre/post scores on a validated questionnaire that measured symptoms of anxiety. RESULTS: Eleven papers met the inclusion criteria, comprising 154 participants assigned to a stimulation condition and 164 to a sham or control group. We calculated Hedge's g for scores on disorder-specific and general anxiety questionnaires before and after treatment to determine effect size, and we conducted 2 independent random-effects meta-analyses. Considering the well-known comorbidity between anxiety and depression, we ran a third meta-analysis analyzing outcomes for depression scores. Results showed a significant effect of noninvasive brain stimulation in reducing scores on disorder-specific and general anxiety questionnaires, as well as depressive symptoms, in the real stimulation compared to the control condition. LIMITATIONS: Few studies met the inclusion criteria; more evidence is needed to strengthen conclusions about the effectiveness of noninvasive brain stimulation in the treatment of anxiety disorders. CONCLUSION: Our findings showed that noninvasive brain stimulation reduced anxiety and depression scores compared to control conditions, suggesting that it can alleviate clinical symptoms in patients with anxiety disorders.


Asunto(s)
Estimulación Transcraneal de Corriente Directa , Trastornos de Ansiedad/terapia , Encéfalo/fisiología , Humanos , Estimulación Transcraneal de Corriente Directa/métodos , Estimulación Magnética Transcraneal/métodos , Resultado del Tratamiento
4.
Neurol Sci ; 41(10): 2711-2735, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32388645

RESUMEN

Event-related potentials (ERPs) are obtained from the electroencephalogram (EEG) or the magnetoencephalogram (MEG, event-related fields (ERF)), extracting the activity that is time-locked to an event. Despite the potential utility of ERP/ERF in cognitive domain, the clinical standardization of their use is presently undefined for most of procedures. The aim of the present review is to establish limits and reliability of ERP medical application, summarize main methodological issues, and present evidence of clinical application and future improvement. The present section of the review focuses on well-standardized ERP methods, including P300, Contingent Negative Variation (CNV), Mismatch Negativity (MMN), and N400, with a chapter dedicated to laser-evoked potentials (LEPs). One section is dedicated to proactive preparatory brain activity as the Bereitschaftspotential and the prefrontal negativity (BP and pN). The P300 and the MMN potentials have a limited but recognized role in the diagnosis of cognitive impairment and consciousness disorders. LEPs have a well-documented usefulness in the diagnosis of neuropathic pain, with low application in clinical assessment of psychophysiological basis of pain. The other ERP components mentioned here, though largely applied in normal and pathological cases and well standardized, are still confined to the research field. CNV, BP, and pN deserve to be largely tested in movement disorders, just to explain possible functional changes in motor preparation circuits subtending different clinical pictures and responses to treatments.


Asunto(s)
Neurociencia Cognitiva , Electroencefalografía , Encéfalo , Potenciales Evocados , Femenino , Humanos , Italia , Masculino , Psicofisiología , Reproducibilidad de los Resultados
5.
Hum Brain Mapp ; 40(12): 3534-3547, 2019 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-31056809

RESUMEN

The knowledge of the size of our own body parts is essential for accurately moving in space and efficiently interact with objects. A distorted perceptual representation of the body size often represents a core diagnostic criterion for some psychopathological conditions. The metric representation of the body was shown to depend on somatosensory afferences: local deafferentation indeed causes a perceptual distortion of the size of the anesthetized body part. A specular effect can be induced by altering the cortical map of body parts in the primary somatosensory cortex. Indeed, the present study demonstrates, in healthy adult participants, that repetitive Transcranial Magnetic Stimulation to the somatosensory cortical map of the hand in both hemispheres causes a perceptual distortion (i.e., an overestimation) of the size of the participants' own hand (Experiments 1-3), which does not involve other body parts (i.e., the foot, Experiment 2). Instead, the stimulation of the inferior parietal lobule of both hemispheres does not affect the perception of the own body size (Experiment 4). These results highlight the role of the primary somatosensory cortex in the building up and updating of the metric of body parts: somatosensory cortical activity not only shapes our somatosensation, it also affects how we perceive the dimension of our body.


Asunto(s)
Tamaño Corporal/fisiología , Conducta de Elección/fisiología , Lateralidad Funcional/fisiología , Imagen por Resonancia Magnética/métodos , Corteza Somatosensorial/diagnóstico por imagen , Corteza Somatosensorial/fisiología , Adulto , Femenino , Mano/fisiología , Humanos , Masculino , Estimulación Luminosa/métodos , Adulto Joven
6.
Cogn Affect Behav Neurosci ; 19(4): 797-810, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-30411201

RESUMEN

Multiple cortical networks intervene in moral judgment, among which the dorsolateral prefrontal cortex (DLPFC) and the medial prefrontal structures (medial PFC) emerged as two major territories, which have been traditionally attributed, respectively, to cognitive control and affective reactions. However, some recent theoretical and empirical accounts disputed this dualistic approach to moral evaluation. In the present study, to further assess the functional contribution of the medial PFC in moral judgment, we modulated its cortical excitability by means of transcranial direct current stimulation (tDCS) and tracked the change in response to different types of moral dilemmas, including switch-like and footbridge-like moral dilemmas, with and without personal involvement. One hundred participants (50 males) completed a questionnaire to assess the baseline levels of deontology. Next, participants were randomly assigned to receive anodal, sham, or cathodal tDCS over the medial prefrontal structures and then were asked to address a series of dilemmas. The results showed that participants who received anodal stimulation over the medial PFC provided more utilitarian responses to switch-like (but not footbridge-like) dilemmas than those who received cathodal tDCS. We also found that neurostimulation modulated the influence that deontology has on moral choices. Specifically, in the anodal tDCS group, participants' decisions were less likely to be influenced by their baseline levels of deontology compared with the sham or cathodal groups. Overall, our results seem to refute a functional role of the medial prefrontal structures purely restricted to affective reactions for moral dilemmas, providing new insights on the functional contribution of the medial PFC in moral judgment.


Asunto(s)
Juicio/fisiología , Principios Morales , Corteza Prefrontal/fisiología , Percepción Social , Estimulación Transcraneal de Corriente Directa , Adulto , Femenino , Humanos , Masculino , Adulto Joven
7.
Cereb Cortex ; 28(4): 1132-1140, 2018 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-28184424

RESUMEN

Increasing evidence shows that anodal transcranial direct current stimulation (tDCS) enhances cognitive performance in healthy and clinical population. Such facilitation is supposed to be linked to plastic changes at relevant cortical sites. However, direct electrophysiological evidence for this causal relationship is still missing. Here, we show that cognitive enhancement occurring in healthy human subjects during anodal tDCS is affected by ongoing brain activity, increasing cortical excitability of task-related brain networks only, as directly measured by Transcranial Magnetic Stimulation combined with electroencephalography (TMS-EEG). Specifically, TMS-EEG recordings were performed before and after anodal tDCS coupled with a verbal fluency task. To control for effects of tDCS protocol and TMS target location, 3 conditions were assessed: anodal/sham tDCS with TMS over left premotor cortex, anodal tDCS with TMS over left posterior parietal cortex. Modulation of cortical excitability occurred only at left Brodmann's areas 6, 44, and 45, a key network for language production, after anodal tDCS and TMS over the premotor cortex, and was positively correlated to the degree of cognitive enhancement. Our results suggest that anodal tDCS specifically affects task-related functional networks active while delivering stimulation, and this boost of specific cortical circuits is correlated to the observed cognitive enhancement.


Asunto(s)
Ondas Encefálicas/fisiología , Corteza Cerebral/fisiología , Cognición/fisiología , Red Nerviosa/fisiología , Plasticidad Neuronal/fisiología , Estimulación Transcraneal de Corriente Directa/métodos , Adulto , Electroencefalografía , Femenino , Humanos , Masculino , Semántica , Estimulación Magnética Transcraneal/métodos , Conducta Verbal , Adulto Joven
8.
Neuroimage ; 178: 475-484, 2018 09.
Artículo en Inglés | MEDLINE | ID: mdl-29860085

RESUMEN

Touch supports processes crucial to human social behaviour, adding a bodily dimension to the perception and understanding of others' feelings. Mirror cortical activity was proposed to underpin the interpersonal sharing of touch, allowing an automatic and unconscious simulation of others' somatic states. However, recent evidence questioned the existence of a tactile shared representation in the primary somatosensory cortex (S1), and the neural correlates of self-other distinction in the somatosensory system remains unknown. We address these issues by exploring S1 reactivity, and the associated neural network oscillations and connectivity, to self and others' touch. Transcranial Magnetic Stimulation combined with Electroencephalography (TMS-EEG) recordings were performed during tactile perception and observation, looking for differences in cortical activation and connectivity between felt and seen touch. The sight of a touch directed to a human body part, but not to an object, triggered an early activation of S1 as a felt touch did, which, in both conditions, propagated to fronto-parietal regions. Critically, touch perception and observation shared an effective connectivity network generated in the beta band, which is typically associated to unconscious tactile processing. Conversely, alpha band connectivity, a marker of conscious tactile processing, was detected only for real tactile stimulation. Alpha connectivity within a fronto-parietal pathway seems to underpin the ability to distinguish self and others' somatosensory states, controlling and distinguishing shared tactile representations in S1.


Asunto(s)
Mapeo Encefálico/métodos , Corteza Somatosensorial/fisiología , Percepción del Tacto/fisiología , Adulto , Electroencefalografía/métodos , Femenino , Humanos , Masculino , Vías Nerviosas/fisiología , Estimulación Magnética Transcraneal/métodos
9.
Exp Brain Res ; 234(2): 627-36, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26573575

RESUMEN

When someone looses one type of sensory input, s/he may compensate by using the sensory information conveyed by other senses. To verify whether loosing a sense or two has consequences on a spared sensory modality, namely touch, and whether these consequences depend on the type of sensory loss, we investigated the effects of deafness and blindness on temporal and spatial tactile tasks in deaf, blind and deaf-blind people. Deaf and deaf-blind people performed the spatial tactile task better than the temporal one, while blind and controls showed the opposite pattern. Deaf and deaf-blind participants were impaired in temporal discrimination as compared to controls, while deaf-blind individuals outperformed blind participants in the spatial tactile task. Overall, sensory-deprived participants did not show an enhanced tactile performance. We speculate that discriminative touch is not so relevant in humans, while social touch is. Probably, more complex tactile tasks would have revealed an increased performance in sensory-deprived people.


Asunto(s)
Ceguera/fisiopatología , Sordera/fisiopatología , Tacto/fisiología , Estimulación Acústica/métodos , Adulto , Anciano , Percepción Auditiva/fisiología , Ceguera/psicología , Sordera/psicología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estimulación Luminosa/métodos , Percepción Visual/fisiología , Adulto Joven
10.
Cogn Behav Neurol ; 29(3): 117-21, 2016 09.
Artículo en Inglés | MEDLINE | ID: mdl-27662449

RESUMEN

In a prior study (Cattaneo et al, 2011. Neuroscience. 183:64-70), we demonstrated that anodal transcranial direct current stimulation (tDCS) over the left inferior frontal gyrus enhanced verbal fluency in healthy young adults. Although our data are in line with the results of other published studies, another research group recently failed to report anodal tDCS effects on verbal fluency using a paradigm similar to ours (Vannorsdall et al, 2016. Cogn Behav Neurol. 29:11-17). Here we discuss aspects of study design and interpretation of results that should be considered in replications, focusing particularly on homogeneity of procedures. Notwithstanding the possibility that our study may indeed not be replicable, we hypothesize that Vannorsdall et al found an interesting modifier of the tDCS effects on verbal production by introducing a critical methodologic difference from our original study. We demonstrate this difference by presenting the results of an additional experiment. We believe that the sharing of data between research groups and constructive debate on possible differences in results should be encouraged because they help define the boundaries of applicability of an experimental paradigm. This is even more important for research findings that may have clinical implications, as is the case here.


Asunto(s)
Lóbulo Frontal , Estimulación Transcraneal de Corriente Directa , Humanos
11.
Psychopathology ; 49(6): 406-419, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27842303

RESUMEN

BACKGROUND: Computerized speech analysis (CSA) is a powerful method that allows one to assess stress-induced mood disturbances and affective disorders through repeated measurements of speaking behavior and voice sound characteristics. Over the past decades CSA has been successfully used in the clinical context to monitor the transition from 'affectively disturbed' to 'normal' among psychiatric patients under treatment. This project, by contrast, aimed to extend the CSA method in such a way that the transition from 'normal' to 'affected' can be detected among subjects of the general population through 10-20 self-assessments. METHODS: Central to the project was a normative speech study of 5 major languages (English, French, German, Italian, and Spanish). Each language comprised 120 subjects stratified according to gender, age, and education with repeated assessments at 14-day intervals (total n = 697). In a first step, we developed a multivariate model to assess affective state and stress-induced bodily reactions through speaking behavior and voice sound characteristics. Secondly, we determined language-, gender-, and age-specific thresholds that draw a line between 'natural fluctuations' and 'significant changes'. Thirdly, we implemented the model along with the underlying methods and normative data in a self-assessment 'voice app' for laptops, tablets, and smartphones. Finally, a longitudinal self-assessment study of 36 subjects was carried out over 14 days to test the performance of the CSA method in home environments. RESULTS: The data showed that speaking behavior and voice sound characteristics can be quantified in a reproducible and language-independent way. Gender and age explained 15-35% of the observed variance, whereas the educational level had a relatively small effect in the range of 1-3%. The self-assessment 'voice app' was realized in modular form so that additional languages can simply be 'plugged in' once the respective normative data become available. Results of the longitudinal self-assessment study in home environments demonstrated that CSA methods work well under most circumstances. CONCLUSIONS: We have successfully developed and tested a self-assessment CSA method that can monitor transitions from 'normal' to 'affected' in subjects of the general population in the broader context of mood disorders. Our easy-to-use 'voice app' evaluates sequences of 10-20 repeated assessments and watches for affect- and stress-induced deviations from baseline that exceed language-, gender-, and age-specific thresholds. Specifically, the 'voice app' provides users with stress-related 'biofeedback' and can help to identify that 10-15% subgroup of the general population that exhibits insufficient coping skills under chronic stress and may benefit from early detection and intervention prior to developing clinically relevant symptoms.


Asunto(s)
Adaptación Psicológica , Trastornos del Humor/diagnóstico , Teléfono Inteligente , Estrés Psicológico/diagnóstico , Comprimidos , Adulto , Femenino , Humanos , Masculino , Trastornos del Humor/psicología , Autoevaluación (Psicología) , Habla , Estrés Psicológico/psicología , Calidad de la Voz
12.
Neuroimage ; 101: 150-8, 2014 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-24983714

RESUMEN

Transcranial magnetic stimulation (TMS) studies show that watching others' movements enhances motor evoked potential (MEPs) amplitude of the muscles involved in the observed action (motor facilitation, MF). MF has been attributed to a mirror neuron system mediated mechanism, causing an excitability increment of primary motor cortex. It is still unclear whether the meaning an action assumes when performed in an interpersonal exchange context could affect MF. This study aims at exploring this issue by measuring MF induced by the observation of the same action coupled with opposite reward values (gain vs loss) in an economic game. Moreover, the interaction frame was manipulated by showing the same actions within different economic games, the Dictator Game (DG) and the Theft Game (TG). Both games involved two players: a Dictator/Thief and a receiver. Experimental participants played the game always as receivers whereas the Dictator/Thief roles were played by our confederates. In each game Dictator/Thief's choices were expressed by showing a grasping action of one of two cylinders, previously associated with fair/unfair choices. In the DG the dictator decides whether to share (gain condition) or not (no-gain condition) a sum of money with the receiver, while in TGs the thief decides whether to steal (loss condition) or not to steal (no-loss condition) it from the participants. While the experimental subjects watched the videos showing these movements, a single TMS pulse was delivered to their motor hand area and a MEP was recorded from the right FDI muscle. Results show that, in the DG, MF was enhanced by the status quo modification, i.e. MEP amplitude increased when the dictator decided to change the receivers' status quo and share his/her money, and this was true when the status quo was more salient. The same was true for the TG, where the reverse happened: MF was higher for trials in which the thief decided to steal the participants' money, thus changing the status quo, in the block in which the status quo maintenance occurred more often. Data support the hypothesis that the economic meaning of the observed actions differently modulates MEP amplitude, pointing at an influence on MF exerted by a peculiar interaction between economic outcomes and variation of the subjects' initial status quo.


Asunto(s)
Potenciales Evocados Motores/fisiología , Relaciones Interpersonales , Corteza Motora/fisiología , Recompensa , Percepción Social , Adulto , Electromiografía , Femenino , Juegos Experimentales , Humanos , Masculino , Principios Morales , Desempeño Psicomotor/fisiología , Estimulación Magnética Transcraneal , Adulto Joven
13.
Ageing Res Rev ; 95: 102207, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38281709

RESUMEN

Parkinson's Disease's (PD) neuropsychological profile is often characterized by altered performance in executive functions (EF) tasks, with a remarkable impact on patients' quality of life. To date, the available neuroimaging literature lacks conclusive evidence about neural patterns underlying EF deficits in PD. Here, we aimed to synthesize the results of PET/fMRI studies examining the differences in brain activation between PD patients and controls during EF tasks, focusing on the three main EF sub-components: cognitive flexibility, working memory, and response inhibition. We conducted a coordinate-based meta-analysis to assess the converging alterations in brain activity in PD patients compared to controls. We assessed the association between aberrant patterns of activity and the EF sub-domains. We found a significant association between hypoactivation patterns in PD converging at the level of the right inferior frontal gyrus in response inhibition tasks, whereas hypoactivation in the left inferior frontal gyrus was found in association with the cognitive flexibility domain. Our results confirm the existence of neural alterations in PD patients in relation to specific EF sub-domains.

14.
iScience ; 26(8): 107430, 2023 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-37575197

RESUMEN

The Bereitschaftspotential (BP), a scalp potential recorded in humans during action preparation, is characterized by a slow amplitude increase over fronto-central regions as action execution approaches. We recorded TMS evoked-potentials (TEP) stimulating the supplementary motor area (SMA) at different time-points during a Go/No-Go task to assess whether and how cortical excitability and connectivity of this region change as the BP increases. When approaching BP peak, left SMA reactivity resulted greater. Concurrently, its effective connectivity increased with the left occipital areas, while it decreased with the right inferior frontal gyrus, indicating a fast reconfiguration of cortical networks during the preparation of the forthcoming action. Functional connectivity patterns supported these findings, suggesting a critical role of frequency-specific inter-areal interactions in implementing top-down mechanisms in the sensorimotor system prior to action. These findings reveal that BP time-course reflects quantitative and qualitative changes in SMA communication patterns that shape mechanisms involved in motor readiness.

15.
Brain Sci ; 12(5)2022 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-35624908

RESUMEN

Due to its safety, portability, and cheapness, transcranial direct current stimulation (tDCS) use largely increased in research and clinical settings. Despite tDCS's wide application, previous works pointed out inconsistent and low replicable results, sometimes leading to extreme conclusions about tDCS's ineffectiveness in modulating behavioral performance across cognitive domains. Traditionally, this variability has been linked to significant differences in the stimulation protocols across studies, including stimulation parameters, target regions, and electrodes montage. Here, we reviewed and discussed evidence of heterogeneity emerging at the intra-study level, namely inter-individual differences that may influence the response to tDCS within each study. This source of variability has been largely neglected by literature, being results mainly analyzed at the group level. Previous research, however, highlighted that only a half-or less-of studies' participants could be classified as responders, being affected by tDCS in the expected direction. Stable and variable inter-individual differences, such as morphological and genetic features vs. hormonal/exogenous substance consumption, partially account for this heterogeneity. Moreover, variability comes from experiments' contextual elements, such as participants' engagement/baseline capacity and individual task difficulty. We concluded that increasing knowledge on inter-dividual differences rather than undermining tDCS effectiveness could enhance protocols' efficiency and reproducibility.

16.
Brain Sci ; 12(4)2022 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-35448011

RESUMEN

Visuo-motor adaptation to optical prisms (Prism Adaptation, PA), displacing the visual scene laterally, is a behavioral method used for the experimental investigation of visuomotor plasticity, and, in clinical settings, for temporarily ameliorating and rehabilitating unilateral spatial neglect. This study investigated the building up of PA, and the presence of the typically occurring subsequent Aftereffects (AEs) in a brain-damaged patient (TMA), suffering from apperceptive agnosia and a right visual half-field defect, with bilateral atrophy of the parieto-occipital cortices, regions involved in PA and AEs. Base-Right prisms and control neutral lenses were used. PA was achieved by repeated pointing movements toward three types of stimuli: visual, auditory, and bimodal audio-visual. The presence and the magnitude of AEs were assessed by proprioceptive, visual, visuo-proprioceptive, and auditory-proprioceptive straight-ahead pointing tasks. The patient's brain connectivity was investigated by Diffusion Tensor Imaging (DTI). Unlike control participants, TMA did not show any adaptation to prism exposure, but her AEs were largely preserved. These findings indicate that AEs may occur even in the absence of PA, as indexed by the reduction of the pointing error, showing a dissociation between the classical measures of PA and AEs. In the PA process, error reduction, and its feedback, may be less central to the building up of AEs, than the sensorimotor pointing activity per se.

17.
Cortex ; 141: 16-35, 2021 08.
Artículo en Inglés | MEDLINE | ID: mdl-34023799

RESUMEN

Prism adaptation (PA) is used to investigate visuo-motor plasticity and to rehabilitate the syndrome of Unilateral Spatial Neglect (USN). After PA, participants show aftereffects (AEs), contralateral to the side of the optical displacement in several tasks. This study explored the features of these AEs, specifically the "egocentric" versus "allocentric, object-based", reference frames involved, and their time course. In three experiments, healthy participants adapted to prismatic lenses inducing a horizontal displacement of the visual field. In Experiment #1, participants adapted to rightward displacing prisms. Four tasks were used requiring repeated pointings towards the participant's subjective egocentric straight-ahead, with the availability of proprioceptive or visual-proprioceptive signals, and, in some conditions, of an external allocentric visual frame (i.e., a rectangular paper sheet). Experiment #2 explored the role of the position of the allocentric frame, with AEs being tested by straight-ahead and frame bisection tasks, requiring pointing toward the external visual frame, placed in different positions of the working space. An egocentric visual proprioceptive task was administered after prism removal and after the execution of the allocentric tasks, to assess the effectiveness of the PA, as indexed by the AEs, and their persistence up to the end of the administration of the allocentric tasks. Experiment #3 differed from #2 in that participants adapted to leftward displacing lenses. Consistent with evidence from USN patients, in Experiment #1, in the egocentric tasks, AEs lasting up to 30 min after PA were found. In Experiment #2, AEs in "allocentric" tasks did not occur, regardless of frame position. Experiment #3 showed AEs in both the "egocentric" and the "allocentric" tasks, with the latter being minor in size. These findings illustrate that the spatial reference systems modulated by PA in extra-personal space primarily operate in spatial "egocentric" reference frames, with a comparatively minor and direction-specific role of "allocentric" frames.


Asunto(s)
Adaptación Fisiológica , Trastornos de la Percepción , Humanos , Estimulación Luminosa , Propiocepción , Percepción Espacial , Campos Visuales
18.
Neuropsychologia ; 150: 107672, 2021 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-33188788

RESUMEN

Adaptation to optical prisms (Prismatic Adaptation, PA) displacing the visual scene laterally, on one side of visual space, is both a procedure for investigating visuo-motor plasticity and a powerful tool for the rehabilitation of Unilateral Spatial Neglect (USN). Two processes are involved in PA: i) recalibration (the reduction of the error of manual pointings toward the direction of the prism-induced displacement of the visual scene); ii) the successive realignment after prisms' removal, indexed by the Aftereffects (AEs, in egocentric straight-ahead pointing tasks, the deviation in a direction opposite to the visual displacement previously induced by prisms). This study investigated the role of the posterior parietal cortex (PPC) of the right hemisphere in PA and AEs, by means of low frequency repetitive Transcranial Magnetic Stimulation (rTMS). Proprioceptive and Visuo-proprioceptive egocentric straight-ahead pointing tasks were used to assess the presence and magnitude of AEs. The primary right visual cortex (V1) was also stimulated, to assess the selectivity of the PPC effects on the two processes of PA (recalibration and realignment) in comparison with a cortical region involved in visual processing. Results showed a slower adaptation to prisms when rTMS was delivered before PA, regardless of target site (right PPC or V1). AEs were reduced only by PPC rTMS applied before or after PA, as compared to a sham stimulation. These findings suggest a functional and neural dissociation between realignment and recalibration. Indeed, PA interference was induced by rTMS to both the PPC and V1, indicating that recalibration is supported by a parieto-occipital network. Conversely, AEs were disrupted only by rTMS delivered to the PPC, thus unveiling a relevant role of this region in the development and maintenance of the realignment.


Asunto(s)
Lateralidad Funcional , Trastornos de la Percepción , Adaptación Fisiológica , Humanos , Lóbulo Parietal , Estimulación Luminosa , Percepción Espacial , Percepción Visual
19.
Artículo en Inglés | MEDLINE | ID: mdl-33219691

RESUMEN

An increasing number of studies suggests that implicit attitudes toward food and body shape predict eating behaviour and characterize patients with eating disorders (EDs). However, literature has not been previously analysed, thus differences between patients with EDs and healthy controls and the level of automaticity of the processes involved in implicit attitudes are still matters of debate. The present systematic review aimed to synthetize current evidence from papers investigating implicit attitudes towards food and body in healthy and EDs populations. PubMed, EMBASE (Ovid), PsycINFO, Web of Science and Scopus were systematically screened and 183 studies using different indirect paradigms were included in the qualitative analysis. The majority of studies reported negative attitudes towards overweight/obese body images in healthy and EDs samples and weight bias as a diffuse stereotypical evaluation. Implicit food attitudes are consistently reported as valid predictors of eating behaviour. Few studies on the neurobiological correlates showed neurostimulation effects on implicit attitudes, but the automaticity at brain level of implicit evaluations remains an open area of research. In conclusion, implicit attitudes are relevant measures of eating behaviour in healthy and clinical settings, although evidence about their neural correlates is limited.

20.
Neuroscience ; 440: 175-185, 2020 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-32497758

RESUMEN

People's identity recognition and the neural correlates underlying this process are still a matter of debate. While neuropsychological reports on single cases show a crucial role of the left anterior temporal lobe (ATL) in proper naming, and of the right ATL in people's identification, reviews are less consistent. Moreover, it is still controversial whether familiarity and personal semantics access rely on amodal processes or follow modality-dependent paths. To disentangle these issues, we tested, in a parallel-group design, neurologically unimpaired subjects in two famous people recognition tasks after anodal tDCS over the left or right ATL or after a placebo stimulation condition. In the famous people recognition task, subjects were presented with visual (face recognition) or auditory (voice recognition) stimuli and subjects had to judge whether stimuli belonged to a famous or non-famous person (familiarity test); then, if the stimulus was recognized as famous, participants had to provide personal semantic information about the character; finally, to investigate proper naming, subjects were asked to name the famous person. While right ATL anodal tDCS increased accuracy in famous faces (but not voices) judgment and personal semantics retrieval, left ATL stimulation increased proper naming for both visual and auditory stimuli. Our data support a key role of the right ATL in famous people recognition and access to personal semantics from visual inputs, while the left ATL seems crucial for proper naming, which seems to occur at a later stage, when presentation modality no longer affects the process.


Asunto(s)
Cara , Lateralidad Funcional , Pruebas Neuropsicológicas , Reconocimiento en Psicología , Semántica , Lóbulo Temporal
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA