Stefano Zago

Improved naming after transcranial direct current stimulation in aphasia

Transcranial direct current stimulation (tDCS) has been proposed as an adjuvant technique to improve functional recovery after ischaemic stroke. This study evaluated the effect of tDCS over the left frontotemporal areas in eight chronic non-fluent post-stroke aphasic patients. The protocol consisted of the assessment of picture naming (accuracy and response time) before and immediately after anodal or cathodal tDCS (2 mA, 10 minutes) and sham stimulation. Whereas anodal tDCS and sham tDCS failed to induce any changes, cathodal tDCS significantly improved the accuracy of the picture naming task by a mean of 33.6% (SEM 13.8%).

Cerebellar transcranial direct current stimulation impairs the practice-dependent proficiency increase in working memory

How the cerebellum is involved in the practice and proficiency of non-motor functions is still unclear. We tested whether transcranial direct current stimulation (tDCS) over the cerebellum (cerebellar tDCS) induces after-effects on the practice-dependent increase in the proficiency of a working memory (WM) task (Sternberg test) in 13 healthy subjects. We also assessed the effects of cerebellar tDCS on visual evoked potentials (VEPs) in four subjects and compared the effects of cerebellar tDCS on the Sternberg test with those elicited by tDCS delivered over the prefrontal cortex in five subjects. Our experiments showed that anodal or cathodal tDCS over the cerebellum impaired the practice-dependent improvement in the reaction times in a WM task. Because tDCS delivered over the prefrontal cortex induced an immediate change in the WM task but left the practice-dependent proficiency unchanged, the effects of cerebellar tDCS are structure-specific. Cerebellar tDCS left VEPs unaffected, its effect on the Sternberg task therefore seems unlikely to arise from visual system involvement. In conclusion, tDCS over the cerebellum specifically impairs the practice-dependent proficiency increase in verbal WM.

Category-specific form-knowledge deficit in a patient with herpes simplex virus encephalitis

Abstract In-depth case study of a herpes simplex virus encephalitis patient who presents with a relatively clear knowledge disorder and anterograde amnesia in the absence of any other major cognitive deficit. The main neuropsychological feature is a category-specific impairment restricted to living things. The patient misnamed pictures of animals and vegetables, could not accurately draw animals from memory or verbally describe their visual appearance, and was not accurate in sorting pictures of real animals from pictures of unreal animals; conversely, in the same tasks her performance with artifactual objects was either errorless or superior to that with animals. We interpret the patients category-specific deficit as due to a selective disturbance within the structural description system, rather than a deficit in low-level visual processing or semantic memory. From this case study and a review of other reported cases we claim that such deficit of form-knowledge is a consequence of the extensive lesions ...

Modulating Human Procedural Learning by Cerebellar Transcranial Direct Current Stimulation

Neuroimaging studies suggest that the cerebellum contributes to human cognitive processing, particularly procedural learning. This type of learning is often described as implicit learning and involves automatic, associative, and unintentional learning processes. Our aim was to investigate whether cerebellar transcranial direct current stimulation (tDCS) influences procedural learning as measured by the serial reaction time task (SRTT), in which subjects make speeded key press responses to visual cues. A preliminary modeling study demonstrated that our electrode montage (active electrode over the cerebellum with an extra-cephalic reference) generated the maximum electric field amplitude in the cerebellum. We enrolled 21 healthy subjects (aged 20–49xa0years). Participants did the SRTT, a visual analogue scale and a visual attention task, before and 35xa0min after receiving 20-min anodal and sham cerebellar tDCS in a randomized order. To avoid carry-over effects, experimental sessions were held at least 1xa0week apart. For our primary outcome measure (difference in RTs for random and repeated blocks) anodal versus sham tDCS, RTs were significantly slower for sham tDCS than for anodal cerebellar tDCS (pu2009=u20090.04), demonstrating that anodal tDCS influenced implicit learning processes. When we assessed RTs for procedural learning across the one to eight blocks, we found that RTs changed significantly after anodal stimulation (interaction “time”u2009×u2009“blocks 1/8”: anodal, pu2009=u20090.006), but after sham tDCS, they remained unchanged (pu2009=u20090.094). No significant changes were found in the other variables assessed. Our finding that anodal cerebellar tDCS improves an implicit learning type essential to the development of several motor skills or cognitive activity suggests that the cerebellum has a critical role in procedural learning. tDCS could be a new tool for improving procedural learning in daily life in healthy subjects and for correcting abnormal learning in neuropsychiatric disorders.

Cerebellum and processing of negative facial emotions: Cerebellar transcranial DC stimulation specifically enhances the emotional recognition of facial anger and sadness

Some evidence suggests that the cerebellum participates in the complex network processing emotional facial expression. To evaluate the role of the cerebellum in recognising facial expressions we delivered transcranial direct current stimulation (tDCS) over the cerebellum and prefrontal cortex. A facial emotion recognition task was administered to 21 healthy subjects before and after cerebellar tDCS; we also tested subjects with a visual attention task and a visual analogue scale (VAS) for mood. Anodal and cathodal cerebellar tDCS both significantly enhanced sensory processing in response to negative facial expressions (anodal tDCS, p=.0021; cathodal tDCS, p=.018), but left positive emotion and neutral facial expressions unchanged (p>.05). tDCS over the right prefrontal cortex left facial expressions of both negative and positive emotion unchanged. These findings suggest that the cerebellum is specifically involved in processing facial expressions of negative emotion.

Gender-related differences in moral judgments

The moral sense is among the most complex aspects of the human mind. Despite substantial evidence confirming gender-related neurobiological and behavioral differences, and psychological research suggesting gender specificities in moral development, whether these differences arise from cultural effects or are innate remains unclear. In this study, we investigated the role of gender, education (general education and health education) and religious belief (Catholic and non-Catholic) on moral choices by testing 50 men and 50 women with a moral judgment task. Whereas we found no differences between the two genders in utilitarian responses to non-moral dilemmas and to impersonal moral dilemmas, men gave significantly more utilitarian answers to personal moral (PM) dilemmas (i.e., those courses of action whose endorsement involves highly emotional decisions). Cultural factors such as education and religion had no effect on performance in the moral judgment task. These findings suggest that the cognitive–emotional processes involved in evaluating PM dilemmas differ in men and in women, possibly reflecting differences in the underlying neural mechanisms. Gender-related determinants of moral behavior may partly explain gender differences in real-life involving power management, economic decision-making, leadership and possibly also aggressive and criminal behaviors.

Brain Switches Utilitarian Behavior: Does Gender Make the Difference?

Decision often implies a utilitarian choice based on personal gain, even at the expense of damaging others. Despite the social implications of utilitarian behavior, its neurophysiological bases remain largely unknown. To assess how the human brain controls utilitarian behavior, we delivered transcranial direct current stimulation (tDCS) over the ventral prefrontal cortex (VPC) and over the occipital cortex (OC) in 78 healthy subjects. Utilitarian judgment was assessed with the moral judgment task before and after tDCS. At baseline, females provided fewer utilitarian answers than males for personal moral dilemmas (pu200a=u200a.007). In males, VPC-tDCS failed to induce changes and in both genders OC-tDCS left utilitarian judgments unchanged. In females, cathodal VPC-tDCS tended to decrease whereas anodal VPC-tDCS significantly increased utilitarian responses (pu200a=u200a.005). In males and females, reaction times for utilitarian responses significantly decreased after cathodal (p<.001) but not after anodal (pu200a=u200a.735) VPC-tDCS. We conclude that ventral prefrontal tDCS interferes with utilitarian decisions, influencing the evaluation of the advantages and disadvantages of each option in both sexes, but does so more strongly in females. Whereas cathodal tDCS alters the time for utilitarian reasoning in both sexes, anodal stimulation interferes more incisively in women, modifying utilitarian reasoning and the possible consequent actions. The gender-related tDCS-induced changes suggest that the VPC differentially controls utilitarian reasoning in females and in males. The gender-specific functional organization of the brain areas involved in utilitarian behavior could be a correlate of the moral and social behavioral differences between the two sexes.

Conflict-dependent dynamic of subthalamic nucleus oscillations during moral decisions.

Although lesional, neuroimaging, and brain stimulation studies have provided an insight into the neural mechanisms of judgement and decision-making, all these works focused on the cerebral cortex, without investigating the role of subcortical structures such as the basal ganglia. Besides being an effective therapeutic tool, deep brain stimulation (DBS) allows local field potential (LFP) recordings through the stimulation electrodes thus providing a physiological “window” on human subcortical structures. In this study we assessed whether subthalamic nucleus LFP oscillations are modulated by processing of moral conflictual, moral nonconflictual, and neutral statements. To do so, in 16 patients with Parkinsons disease (8 men) bilaterally implanted with subthalamic nucleus (STN) electrodes for DBS, we recorded STN LFPs 4 days after surgery during a moral decision task. During the task, recordings from the STN showed changes in LFP oscillations. Whereas the 14–30 Hz band (beta) changed during the movement executed to perform the task, the 5–13 Hz band (low-frequency) changed when subjects evaluated the content of statements. Low-frequency band power increased significantly more during conflictual than during nonconflictual or neutral sentences. We conclude that STN responds specifically to conflictual moral stimuli, and could be involved in conflictual decisions of all kinds, not only those for moral judgment. LFP oscillations provide novel direct evidence that the neural processing of conflictual decision-making spreads beyond the cortex to the basal ganglia and encompasses a specific subcortical conflict-dependent component.

Neuropsychology, social cognition and global functioning among bipolar, schizophrenic patients and healthy controls: Preliminary data

This study aimed to determine the extent of impairment in social and non-social cognitive domains in an ecological context comparing bipolar (BD), schizophrenic (SKZ) patients and healthy controls (HC). The sample was enrolled at the Department of Psychiatry of Policlinico Hospital, University of Milan; it includes stabilized SKZ patients (n = 30), euthymic bipolar patients (n = 18) and HC (n = 18). Patients and controls completed psychiatric assessment rating scales, the Brief Assessment of Cognition in Schizophrenia (BACS) and the Executive and Social Cognition Battery (ESCB) that contains both ecological tests of executive function and social cognition, in order to better detect cognitive deficits in patients with normal results in standard executive batteries. The three groups differed significantly for gender and substance abuse, however, the differences did not influence the results. BD patients showed less impairment on cognitive performance compared to SKZ patients, even in “ecological” tests that mimic real life scenarios. In particular, BD performed better than SKZ in verbal memory (p < 0.0038) and BACS symbol coding (p < 0.0043). Regarding the ESCB tests, in the Hotel task SKZ patients completed significantly less tasks (p < 0.001), showed a greater number of errors in Multiple Errands Test (MET-HV) (p < 0.0248) and a worse performance in Theory of Mind (ToM) tests (p < 0.001 for the Eyes test and Faux pas test). Both patients groups performed significantly worse than HC. Finally, significant differences were found between the two groups in GAF scores, being greater among BD subjects (p < 0.001). GAF was correlated with BACS and ESCB scores showing the crucial role of cognitive and ecological performances in patients global functioning.

Bartholow, Sciamanna, Alberti: Pioneers in the Electrical Stimulation of the Exposed Human Cerebral Cortex

Although the past 25 years have witnessed increasing interest in human brain stimulation, its historical development is marked by phases of fascination and obscurity. Its history dates back to the 19th century when the first reports describing application of an electric current to an isolated point on the exposed brain made brain stimulation a major neuroscientific novelty of the time. In this article, the authors present and discuss a number of early experiments involving electrical stimulation of the exposed human brain. In this important, albeit unexplored, historical chapter of brain stimulation, the 3 investigators, Bartholow, Sciamanna, and Alberti, were the first to reproduce findings in animals with electrical brain stimulation in humans. NEUROSCIENTIST 14(5):521—528, 2008. DOI: 10.1177/1073858407311101