The role of Posterior Parietal Cortex in spatial representation of time: a TMS study.

1. Introduction. The existence of a spatial representation of time, where temporal intervals are represented on a mental temporal line (MTL), oriented in ascending order from left to right, was demonstrated manipulating spatial attention by means of Prismatic Adaptation (PA). In young healthy subjects, prisms adaptation inducing a rightward shift of spatialattention produced an overestimation of time intervals, whereas prisms adaptation inducing a leftward shift of spatialattention produced an underestimation of time intervals [4]. The aimof the present study was to investigate the neural basis mediating the effects of PA on spatial time representation. PosteriorParietalCortex (PPC) is the …

Transcranial Magnetic Stimulation Trains at 1 Hz Frequency of the Right Posterior Parietal Cortex Facilitate Recognition Memory

Neuroimaging, neuropsychological, and brain stimulation studies have led to contrasting findings regarding the potential roles of the lateral parietal lobe in episodic memory. Studies using brain stimulation methods reported in the literature do not offer unequivocal findings on the interactions with stimulation location (left vs. right hemisphere) or timing of the stimulation (encoding vs. retrieval). To address these issues, active and sham 1 Hz repetitive transcranial magnetic stimulation (rTMS) trains of 600 stimuli were applied over the right or left posterior parietal cortex (PPC) before the encoding or before the retrieval phase of a recognition memory task of unknown faces in a grou…

De novo GRIN2A variants associated with epilepsy and autism and literature review

N-methyl-D-aspartate receptors (NMDAR) are di- or tri-heterotetrameric ligand-gated ion channels composed of two obligate glycine-binding GluN1 subunits and two glutamate-binding GluN2 or GluN3 subunits, encoded by GRIN1, GRIN2A–D, and GRIN3A–B receptor genes respectively. Each NMDA receptor subtype has different temporal and spatial expression patterns in the brain and varies in the cell types and subcellular localization resulting in different functions. They play a crucial role in mediating the excitatory neurotransmission, but are also involved in neuronal development and synaptic plasticity, essential for learning, memory, and high cognitive functions. Among genes coding NMDAR subunits…

Modulating memory performance in healthy subjects with Trancranial Direct Current Stimulation over the right dorsolateral prefrontal cortex

Objective: The role of the Dorsolateral Prefrontal Cortex (DLPFC) in recognition memory has been well documented in lesion, neuroimaging and repetitive Transcranial Magnetic Stimulation (rTMS) studies. The aim of the present study was to investigate the effects of transcranial Direct Current Stimulation (tDCS) over the left and the right DLPFC during the delay interval of a non-verbal recognition memory task. Method: 36 right-handed young healthy subjects participated in the study. The experimental task was an Italian version of Recognition Memory Test for unknown faces. Study included two experiments: in a first experiment, each subject underwent one session of sham tDCS and one session of…

Benign Nocturnal Alternating Hemiplegia Of Childhood: A New Case.

Reduction of drive for thinness and body dissatisfaction in people with self-reported dysregulated eating behaviors after intermittent theta burst stimulation (iTBS) of the left dorsolateral prefrontal cortex

AimThis study aimed to explore the effect of intermittent theta burst stimulation (iTBS) of the right and left dorsolateral prefrontal cortex (DLPFC) in people with self-reported dysregulated eating behaviors but without a diagnosis of eating disorders (EDs).MethodsParticipants were randomly divided into two equivalent groups according to the side (right or left) of the hemisphere to be stimulated and they were tested before and after a single iTBS session. Outcome measurements were scores on self-report questionnaires assessing psychological dimensions related to eating behaviors (EDI-3), anxiety (STAI-Y), and tonic electrodermal activity.ResultsThe iTBS interfered with both psychological …

Interferenza tra il livello dell’oggetto e attributi di base in stimuli visivi: studio su pazienti con lesione cerebrale.

Introduzione. In compiti di ricerca visiva i processi top-down coinvolti nel riconoscimento della forma dell’oggetto possono interferire nella elaborazione bottom-up degli attributi elementari che compongono l’oggetto. La performance in tali compiti può essere facilitata dopo inibizione selettiva della corteccia parietale destra tramite r-TMS. In questo studio abbiamo indagato il ruolo di lesioni cerebrali nei compiti di ricerca visiva per singole caratteristiche caratterizzati da interferenza tra il livello dell’oggetto e degli attributi elementari. Pazienti con lesione focale del lobo parietale potrebbero paradossalmente non risentire dell’effetto interferente esercitato dal riconosciment…

Combining tDCS with prismatic adaptation for non-invasive neuromodulation of the motor cortex

Abstract Background Prismatic adaptation (PA) shifts visual field laterally and induces lateralized deviations of spatial attention. Recently, it has been suggested that prismatic goggles are also able to modulate brain excitability, with cognitive after-effects documented even in tasks not necessarily spatial in nature. Objective The aim of the present study was to test whether neuromodulatory effects obtained from tDCS and prismatic goggles could interact and induce homeostatic changes in corticospinal excitability. Methods Thirty-four subjects were submitted to single-pulse transcranial magnetic stimulation (TMS) over the right primary motor cortex to measure Input-Output (IO) curve as a…

Repetitive transcranial magnetic stimulation over the left parietal cortex facilitates visual search for a letter among its mirror images

Interference by task irrelevant information is seen in visual search paradigms using letters. Thus, it is harder to find the letter 'N' among its mirror reversals 'Icyrillic' than vice versa. This observation, termed the reversed letter effect, involves both a linguistic association and an interference of task irrelevant information - the shape of 'N' or 'Icyrillic' is irrelevant, the search requires merely distinguishing the tilts of oblique bars. We adapted the repetitive transcranial magnetic stimulation (rTMS) methods that we previously used, and conducted three rTMS experiments using healthy subjects. The first experiment investigated the effects of rTMS on the left and right posterior…

Boosting Phonological Fluency Following Leftward Prismatic Adaptation: A New Neuromodulation Protocol for Neurological Deficits?

Abstract Prism adaptation (PA) has been recently shown to modulate a brain frontal-parieto-temporal network, with an increase of excitation of this network in the hemisphere ipsilateral to the side of prismatic deviation. This effect raises the hypothesis that left prismatic adaptation, modulating the excitability of frontal areas of the left hemisphere, could modulate subjects’ performance on linguistic tasks that map on those areas.To test this hypothesis, sixty-one healthy subjects participated in experiments in which leftward, rightward or no-PA were applied before the execution of a phonological fluency task, i.e. a task with strict left hemispheric lateralization and mapping onto fron…

Facilitation of bottom-up feature detection following rTMS-interference of the right parietal cortex

In visual search tasks the optimal strategy should utilize relevant information ignoring irrelevant one. When the information at the feature and object levels are in conflict, un-necessary processing at higher level of object shape can interfere with detection of lower level orientation feature. We explored the effects of inhibitory trains of transcranial magnetic stimulation (rTMS) on the right and left parietal cortex in healthy subjects performing two visual search tasks. One task (Task A) was characterised by an object-to-feature interference. The other task (Task B) was without such interference. We found that rTMS of the right parietal cortex significantly reduced reaction times (RTs)…

The Posterior Parietal Cortex and the spatial representation of time

Low-Frequency Repetitive Transcranial Magnetic Stimulation of the Right Dorsolateral Prefrontal Cortex Enhances Recognition Memory in Alzheimer’s Disease

Background: The lack of effective pharmacological or behavioral interventions for memory impairments associated with Alzheimer’s disease (AD) emphasizes the need for the investigation of approaches based on neuromodulation. Objective: This study examined the effects of inhibitory repetitive transcranial magnetic stimulation (rTMS) of prefrontal cortex on recognition memory in AD patients. Methods: In a first experiment, 24 mild AD patients received sham and real 1Hz rTMS over the left and right dorsolateral prefrontal cortex (DLPFC), in different sessions, between encoding and retrieval phases of a non-verbal recognition memory task. In a second experiment, another group of 14 AD patients u…

Exploring the neural correlates of the reversed letter effect: Evidence from left and right parietal patients.

To investigate the hemispheric lateralization of attentional processes during visual search tasks depending on the stimulus material embedding the target, twelve patients with unilateral left (n = 7) or right (n = 5) parietal lesions and 20 age and education matched healthy controls (HC) were recruited. We used a visual search task for a uniquely tilted oblique bar embedded in an object shape 'N' or in its mirror reversal 'И'. The accuracy and the averaged reaction times (RTs) in each stimulus type ('N' or 'И') were analysed.\ud \ud HC presented significantly longer RTs when the target bar was embedded in 'N' among its mirror reversed 'И' (p < .05). This “reversed letter effect” was also…

Improvement of phonemic fluency following leftward prism adaptation.

AbstractAnatomo functional studies of prism adaptation (PA) have been shown to modulate a brain frontal-parieto-temporal network, increasing activation of this network in the hemisphere ipsilateral to the side of prism deviation. This effect raises the hypothesis that left prism adaptation, modulating frontal areas of the left hemisphere, could modify subjects’ performance on linguistic tasks that map on those areas. To test this hypothesis, 51 healthy subjects participated in experiments in which leftward or rightward prism adaptation were applied before the execution of a phonemic fluency task, i.e., a task with strict left hemispheric lateralization onto frontal areas. Results showed tha…

Effetti della TMS parietale e dei prismi nella percezione di intervalli temporali

West syndrome followed by juvenile myoclonic epilepsy: a coincidental occurrence?

Background: West syndrome is an age-dependent epilepsy with onset peak in the first year of life whose aetiology may be symptomatic or cryptogenic. Long-term cognitive and neurological prognosis is usually poor and seizure outcome is also variable. Over the past two decades a few patients with favourable cognitive outcome and with total recovery from seizures were identified among the cryptogenic group suggesting an idiopathic aetiology. Recent research has described two children with idiopathic WS who later developed a childhood absence epilepsy. Case presentation: We reviewed the medical records of patients with West syndrome admitted to the our Child Neuropsychiatry Unit in the last 15 y…

The role of posterior parietal cortices on prismatic adaptation effects on the representation of time intervals

Previous studies provided evidence of an ascending left-to-right spatial representation of time durations by using a technique affecting high levels of spatial cognition, i.e. prismatic adaptation (PA). Indeed, PA that induced a leftward aftereffect distorted time representation toward an underestimation, while PA that induced a rightward aftereffect distorted time representation toward an overestimation. The present study advances previous findings on the effects of PA on time by investigating the neural basis subtending these effects. We focused on the posterior parietal cortex (PPC) since it is involved in the PA procedure and also in the formulation of the spatial representation of time…

Ruolo dei processitop-down e bottom-up in compiti di ricerca visiva: studi con r-TMS

Benign nocturnal alternating hemiplegia of childhood: a new case with unusual findings

Abstract It has been described a neuro developmental disorder labelled “Benign nocturnal alternating hemiplegia of childhood” (BNAHC) characterized by recurrent attacks of nocturnal hemiplegia without progression to neurological or intellectual impairment. We report a female patient who at 11 months revealed a motionless left arm, unusual crying without impairment of consciousness and obvious precipitating factors. The attacks occur during sleep in the early morning with lack of ictal and interictal electroencephalographic abnormalities, progressive neurological deficit, and cognitive impairment. Unlike previous reports of BNAHC our patient come from a family with a history of both migraine…

Nuove metodologie per lo studio della malattia di Parkinson.

Low frequency rTMS over the right parietal cortex at retrieval increases recognition memory in healthy subjects

Neuroimaging and lesion studies have led to contrasting findings regarding the potential role of the parietal lobe in episodic memory. Imaging studies strongly suggest an important participation of the posterior parietal cortex (PPC) in episodic memory, whereas lesion studies are not conclusive at this regard. Using off-line 1 Hz rTMS paradigm, we conducted 2 experiments to investigate the role of PPCs in recognition memory. Real or sham rTMS were applied over the left or the right PPC (P3 and P4 of the 10–20 EEG system) of healthy subjects before encoding (Experiment 1) and just before retrieval (Experiment 2) of forced-choice non verbal recognition memory tasks. rTMS over the left and the…

Processing Past Tense in the left cerebellum

We report the case of a patient with ischemic lesion of the left cerebellum, who showed specific deficits in processing past versus future tense of action verbs. These findings confirm, in the presence of cerebellar damage, previous results obtained with transcranial magnetic stimulation in healthy subjects and suggest a specificity of the left cerebellum for preparation of responses to the past tense of action verbs. As part of the procedural brain, the cerebellum could play a role in applying the linguistic rules for selection of morphemes typical of past and future tense formation.

Rappresentazione del tempo del verbo nel cervello: il ruolo del cervelletto

Impairments in top down attentional processes in right parietal patients: Paradoxical functional facilitation in visual search

AbstractIt is well known that the right posterior parietal cortex (PPC) is involved in attentional processes, including binding features. It remains unclear whether PPC is implicated in top-down and/or bottom-up components of attention. We aim to clarify this by comparing performance of seven PPC patients and healthy controls (HC) in a visual search task involving a conflict between top-down and bottom-up processes. This task requires essentially a bottom-up feature search. However, top-down attention triggers feature binding for object recognition, designed to be irrelevant but interfering to the task. This results in top-down interference, prolonging the search reaction time. This interfe…

Facilitation in Visual Search for Reversed Letters Following r-TMS of the Left Parietal Cortex

Recurrent missense variant in the nuclear export signal of FMR1 associated with FXS-like phenotype including intellectual disability, ASD, facial abnormalities

Fragile X syndrome (FXS; MIM 300624) is an X-linked genetic disorder characterized by physical abnormalities associated with intellectual disability and a wide spectrum of neurological and psychiatric impairments. FXS occurs more frequently in males, 1 in 5000 males and 1 in 8000 females accounting for 1-2% of overall intellectual disability (ID). In more than 99% of patients, FXS results from expansions of a CGG triplet repeat (>200 in male) of the FMR1 gene. In the last years an increasing number, albeit still limited, of FXS subjects carrying FMR1 mutations including deletions, splicing errors, missense, and nonsense variants was reported. Nevertheless, the studies concerning the func…

Enhancing memory performance with rTMS in healthy subjects and individuals with Mild Cognitive Impairment: the role of the right dorsolateral prefrontal cortex

A debated question in the literature is the degree of anatomical and functional lateralization of the executive control processes subserved by the dorsolateral prefrontal cortex (DLPFC) during recognition memory retrieval. We investigated if transient inhibition and excitation of the left and right DLPFC at retrieval by means of repetitive transcranial magnetic stimulation (rTMS) modulate recognition memory performance in 100 healthy controls (HCs) and in 8 patients with Mild Cognitive Impairment (MCI). Recognition memory tasks of faces, buildings and words were used in different experiments. rTMS-inhibition of the right DLPFC enhanced recognition memory of verbal and non verbal material in…

Modulating phonemic fluency performance in healthy subjects with transcranial magnetic stimulation over the left or right lateral frontal cortex.

Abstract A growing body of evidence have suggested that non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), can improve the performance of aphasic patients in language tasks. For example, application of inhibitory rTMS or tDCs over the right frontal lobe of dysphasic patients resulted in improved naming abilities. Several studies have also reported that in healthy controls (HC) tDCS application over the left prefrontal cortex (PFC) improve performance in naming and semantic fluency tasks. The aim of this study was to investigate in HC, for the first time, the effects of inhibitory repetitive TMS (rTMS…

Facilitazioni paradossali in compiti di ricerca visiva in pazienti con lesione parietale destra.

Introduzione. In compiti di ricerca visiva i processi top-down coinvolti nel riconoscimento della forma dell’oggetto possono interferire nella elaborazione bottom-up degli attributi elementari che compongono l’oggetto. Precedenti studi r-TMS hanno documentato che la performance in tali compiti può essere facilitata dopo inibizione selettiva della corteccia parietale destra. L’ipotesi alla base del presente studio è che pazienti con lesione focale parietale destra potrebbero non risentire dell’effetto interferente esercitato dal riconoscimento della forma dell’oggetto in compiti di ricerca visiva di singole caratteristiche. Metodo. Hanno partecipato allo studio sette pazienti (2 femmine e 5 …

Disturbi cognitivi nell'epilessia del lobo temporale in età evolutiva

Objectives. To describe the impact of childhood temporal lobe epilepsy (TLE) on cognitive functions. Material and methods. Nine patients with TLE aged 11-17 years and 18 healty controls were investigated with a comprehensive neuropsychological assessment. Results. The performance of children with TLE was significantly worse across language, verbal short term memory and semantic tests, compared with the controls. Verbal and non-verbal recall was also impaired. A supplementary investigation of recognition memory showed a selective impairment in topographical memory. Conclusions. In our patients, the episodic memory impairment is similar, although less severe, to that reported in developmental…

Impact of Perceived Stress and Immune Status on Decision-Making Abilities during COVID-19 Pandemic Lockdown.

The ability to make risky decisions in stressful contexts has been largely investigated in experimental settings. We examined this ability during the first months of COVID-19 pandemic, when in Italy people were exposed to a prolonged stress condition, mainly caused by a rigid lockdown. Participants among the general population completed two cognitive tasks, an Iowa Gambling Task (IGT), which measures individual risk/reward decision-making tendencies, and a Go/No-Go task (GNG), to test impulsivity, together with two questionnaires, the Perceived Stress Scale and the Depression, Anxiety and Stress Scales. The Immune Status Questionnaire was additionally administered to explore the impact of t…

Evaluating the role of dorsolateral prefrontal cortex on recognition memory with rTMS: evidence from healthy subjects and neurological patients

Converging evidence from functional imaging and lesion studies suggested that a distributed neural network comprising the hippocampal formation, medial and lateral parietal regions as well as the prefrontal cortex is involved in episodic memory. Some findings suggested that successful memory formation requires the coordinated modulation of neural activity among these different cortical areas. It appears particularly important to understand the functional interactions between these regions during memory processes. My talk will be focused on the prefrontal contribution to verbal and non-verbal recognition memory and to familiarity and recollection processes. New evidence will be provided and …

Benign myoclonic epilepsy in infancy followed by childhood absence epilepsy

Abstract Benign myoclonic epilepsy in infancy (BMEI) is a rare syndrome included among idiopathic generalized epilepsies (IGE) and syndromes with age-related onset. Recently, it has been shown that a few patients with BMEI later had other epilepsy types mainly IGE but never childhood absence epilepsy (CAE). We report a patient who at 11 months of age showed isolated myoclonic jerks occurring several times a day. The ictal video-EEG and polygraphic recording revealed generalized discharge of spike-wave (SW) lasting 1–2s associated with isolated bilateral synchronous jerk involving mainly the upper limbs controlled by valproic acid (VPA). At 6 years and 8 months the child developed a new elec…

ATROFIA DENTATO-RUBRO-PALLIDO-LUYSIANA AD ESORDIO PRECOCE: ASPETTI NEUROPSICOLOGICI.