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

Transcranial direct current stimulation over the right intraparietal sulcus improves response inhibition

Various situations in our everyday life call for response inhibition, mechanisms deputed to outright stop an ongoing course of action. This function reportedly involves the activity of the right intraparietal sulcus (rIPS). This study aimed to determine whether transcranial direct current stimulation (tDCS) intervention to the rIPS alters response inhibition. We investigated 15 healthy adults performing a stop signal task before and after tDCS intervention. We applied tDCS with 1.5 mA to the rIPS directly above (P4) and the left supraorbital area for 20 min. The stimulation conditions involved Anodal, cathodal, and pseudo-stimulation. Each participant performed a stop signal task under all stimulation conditions. The changes in response inhibition function were evaluated by comparing the stop signal reaction times (SSRT) before and after the tDCS intervention. Under the Anodal condition, SSRT was significantly shorter after than before the intervention (p = 0.014). Under the Anodal and Cathodal conditions, we could observe a significantly positive correlation between the SSRT before the tDCS intervention and the difference in SSRT before and after tDCS intervention (Anodal condition: r = 0.823, p < 0.001; Cathodal condition: r = 0.831, p < 0.001). No such correlation could be found under the Sham condition. In summary, this study demonstrated that Anodal-tDCS intervention for rIPS improves response-inhibitory function and the stimulus effect depends on the response-inhibitory function of the participant prior to stimulation.

Facial Emotion Recognition in Children and Adolescents with Specific Learning Disorder

BACKGROUND

Some recent studies suggest that children and adolescents with different neurodevelopmental disorders perform worse in emotions recognition through facial expressions (ER) compared with typically developing peers. This impairment is also described in children with Specific Learning Disorders (SLD), compromising their scholastic achievement, social functioning, and quality of life. The purpose of our study is to evaluate ER skills in children and adolescents with SLD compared to a control group without learning disorders, and correlate them with intelligence and executive functions.

MATERIALS AND METHODS

Our work is a cross-sectional observational study. Sixty-three children and adolescents aged between 8 and 16 years, diagnosed with SLD, and 32 sex/age-matched controls without learning disorders were recruited. All participants were administered standardized neuropsychological tests, evaluating facial emotion recognition (NEPSY-II), executive functions (EpiTrack Junior), and intelligence profile (WISC-IV).

RESULTS

Emotion recognition mean score was significantly lower in the SLD group than in the controls group on the Mann-Whitney U test for unpaired samples (p < 0.001). The SLD group performed significantly lower than the control group in their abilities to identify neutral expressions, happiness, sadness, anger, and fear compared to controls (p < 0.001). ER scores were positively correlated to the executive functions scores. There was no correlation with the Total Intelligence Quotient scores but there is a significant positive correlation with Working Memory Index and Processing Speed Index measured by WISC.IV.

CONCLUSION

Our study showed that children and adolescents with Specific Learning Disorders have facial emotion recognition impairment when compared with a group of peers without learning disorders. ER abilities were independent of their global intelligence but potentially related to executive functions.

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. 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 found in the right parietal patients (p < .001), while no evidence of a reversed letter effect was found in the left parietal patients.

Early detection of memory impairments in older adults: standardization of a short version of the verbal and nonverbal Recognition Memory Test

In several neurological conditions, in elderly and cognitively impaired subjects, memory functioning must be evaluated to early detect the cognitive deterioration processes. In particular, recognition memory assessment is an essential step in the clinical and neuropsychological evaluation of early memory impairments. The Recognition Memory Test (RMT) developed by Smirni et al. (G Ital Psicol XXXVII(1):325-343, 2010) is an effective instrument to assess verbal and nonverbal recognition memory in the Italian population. The current study provides a new, brief, and reliable RMT format to evaluate recognition memory on elderly subjects and it reports normative data in an older adult Italian population sample (including 100 participants well distributed across sex, education, and age categories). The shortened version of RMT keeps the administration procedures and materials of the original Italian RMT constant, i.e., words, faces, and buildings. Multiple regression analysis revealed significant effects of age and educational level on performance but no effect of sex. Inferential cutoffs have been determined and equivalent scores computed. The availability of equivalent scores for the Recognition Memory Test will prove useful in the clinical evaluation of patients' memory profiles.

Navigational cue effects in Alzheimer's disease and posterior cortical atrophy

Objective

Deficits in spatial navigation are characteristic and disabling features of typical Alzheimer's disease (tAD) and posterior cortical atrophy (PCA). Visual cues have been proposed to mitigate such deficits; however, there is currently little empirical evidence for their use.

Methods

The effect of visual cues on visually guided navigation was assessed within a simplified real-world setting in individuals with tAD (n = 10), PCA (n = 8), and healthy controls (n = 12). In a repeated-measures design comprising 36 trials, participants walked to a visible target destination (an open door within a built environment), with or without the presence of an obstacle. Contrast and motion-based cues were evaluated; both aimed to facilitate performance by applying perceptual changes to target destinations without carrying explicit information. The primary outcome was completion time; secondary outcomes were measures of fixation position and walking path directness during consecutive task phases, determined using mobile eyetracking and motion capture methods.

Results

Results illustrate marked deficits in patients' navigational ability, with patient groups taking an estimated two to three times longer to reach target destinations than controls and exhibiting tortuous walking paths. There were no significant differences between tAD and PCA task performance. Overall, patients took less time to reach target destinations under cue conditions (contrast-cue: 11.8%; 95% CI: [2.5, 20.3]) and were more likely initially to fixate on targets.

Interpretation

The study evaluated navigation to destinations within a real-world environment. There is evidence that introducing perceptual changes to the environment may improve patients' navigational ability.

Benton visual form discrimination test in healthy children: normative data and qualitative analysis

The attention evaluation may be considered a crucial phase in neuropsychological assessment. It must take into account the systemic nature of the attentional functions and must use different reliable tests in relation to the neurological and attentional problems to be addressed. The aim of the study was to offer the clinician an effective tool for attention assessment and provide the normative data and performance analysis on the Benton Visual Form Discrimination Test on an Italian sample (number 323) of healthy school children, from ages 5 to 11. Performance on Visual Form Discrimination Test (VFDT) significantly increased with growing age. Performances were significantly different when the test was divided into four sets. All groups, especially the younger ones, showed some difficulty in maintenance and sustained attention. The correct answers were significantly more numerous when they were placed at the top quadrants. This effect was more marked in the younger groups. Sex was never a significantly influencing performance. Our data seem to indicate that the higher attentional frontoparietal network becomes more functionally organized around 9-10 years. VFDT appears as a discriminative task. In clinical practice, our normative data can be used both on complex visual attention skill evaluation in children and on the ability to maintain visual attention in time.

Effects of scanner acoustic noise on intrinsic brain activity during auditory stimulation

INTRODUCTION

Although the effects of scanner background noise (SBN) during functional magnetic resonance imaging (fMRI) have been extensively investigated for the brain regions involved in auditory processing, its impact on other types of intrinsic brain activity has largely been neglected. The present study evaluated the influence of SBN on a number of intrinsic connectivity networks (ICNs) during auditory stimulation by comparing the results obtained using sparse temporal acquisition (STA) with those using continuous acquisition (CA).

METHODS

Fourteen healthy subjects were presented with classical music pieces in a block paradigm during two sessions of STA and CA. A volume-matched CA dataset (CAm) was generated by subsampling the CA dataset to temporally match it with the STA data. Independent component analysis was performed on the concatenated STA-CAm datasets, and voxel data, time courses, power spectra, and functional connectivity were compared.

RESULTS

The ICA revealed 19 ICNs; the auditory, default mode, salience, and frontoparietal networks showed greater activity in the STA. The spectral peaks in 17 networks corresponded to the stimulation cycles in the STA, while only five networks displayed this correspondence in the CA. The dorsal default mode and salience networks exhibited stronger correlations with the stimulus waveform in the STA.

CONCLUSIONS

SBN appeared to influence not only the areas of auditory response but also the majority of other ICNs, including attention and sensory networks. Therefore, SBN should be regarded as a serious nuisance factor during fMRI studies investigating intrinsic brain activity under external stimulation or task loads.