Dyslexia and Cerebral Dysfunction

Children with slow visual-motor responses to visual-temporal response tests also have brain dysfunctions in the mobile and motor areas (6, 4). If the left parietal cortex does not participate in these dysfunctions, then this child will also have difficulties in reading. Furthermore, we could say that the brain dysfunctions that are detected by visual-motor tests and that the performance in them is low, are accompanied by difficulties in reading. Aim: In this study we want to show the function of the child's brain in dyslexia. Method: We followed the most up-to-date literature on the subject: neuropsychology and dyslexia. Conclusions: brain organization and its relationship to dyslexia is a major problem for Neuropsychology and Neurolinguistics.

Dyslexia and Cerebral Dysfunction

Children with slow visual-motor responses to visual-temporal response tests also have brain dysfunctions in the mobile and motor areas [6,4]. If the left parietal cortex does not participate in these dysfunctions, then this child will also have difficulties in reading. Furthermore, we could say that the brain dysfunctions that are detected by visual-motor tests and that the performance in them is low, are accompanied by difficulties in reading. Aim: In this study we want to show the function of the child’s brain in dyslexia. Method: We followed the most up-to-date literature on the subject: neuropsychology and dyslexia. Conclusions: brain organization and its relationship to dyslexia is a major problem for Neuropsychology and Neurolinguistics.

Precision Repetitive Transcranial Magnetic Stimulation Over the Left Parietal Cortex Improves Memory in Alzheimer’s Disease: A Randomized, Double-Blind, Sham-Controlled Study

ObjectiveWe aim to study the effect of precision repetitive transcranial magnetic stimulation (rTMS) over the left parietal cortex on the memory and cognitive function in Alzheimer’s disease (AD).MethodsBased on the resting-state functional magnetic resonance imaging, the left parietal cortex site with the highest functional connectivity to the hippocampus was selected as the target of rTMS treatment. Sixty-nine AD patients were randomized to either rTMS or sham treatment (five sessions/week for a total of 10 sessions). The Mini-Mental State Examination (MMSE), 12-Word Philadelphia Verbal Learning Test (PVLT), and Clinical Dementia Rating (CDR) were assessed at baseline and after the last session.ResultsAfter a 2-week treatment, compared to patients in the sham group, those in the rTMS group scored significantly higher on PVLT total score and its immediate recall subscale score. Moreover, in the rTMS group, there were significant improvements after the 2-week treatment, which were manifested in MMSE total score and its time orientation and recall subscale scores, as well as PVLT total score and its immediate recall and short delay recall subscale scores. In the sham group, the PVLT total score was significantly improved.ConclusionThe target site of the left parietal cortex can improve AD patients’ cognitive function, especially memory, providing a potential therapy.

Tactile to visual number priming in the left intraparietal cortex of sighted Braille readers

Numbers can be presented in different notations and sensory modalities. It is currently debated to what extent these formats overlap onto a single representation. We asked whether such an overlap exists between symbolic numbers represented in two sensory modalities: Arabic digits and Braille numbers. A unique group of sighted Braille readers underwent extensive Braille reading training and was tested in an fMRI repetition-suppression paradigm with tactile Braille digit primes and visual Arabic digit targets. Our results reveal cross-modal priming: compared to repetition of two different quantities (e.g., Braille “5” and Arabic “2”), repetition of the same quantity presented in two modalities (e.g., Braille “5” and Arabic “5”) led to a reduction of activation in several sub-regions of the Intraparietal Sulcus (IPS), a key cortical region for magnitude processing. Thus, in sighted Braille readers, the representations of numbers read by sight and by touch overlap to a degree sufficient to cause repetition suppression. This effect was modulated by the numerical prime-probe distance. Altogether this indicates that the left parietal cortex hosts neural assemblies that are sensitive to numerical information from different notations (number words or Arabic digits) and modalities (tactile and visual).

The effects of multi-day rTMS and cardiorespiratory fitness on working memory and local GABA concentration

Working memory (WM) refers to the capacity to temporarily retain and manipulate finite amounts of information; a critical process in complex behaviours such as reasoning, comprehension, and learning. This cognitive function is supported by a parietal-prefrontal network and linked to the activity of key brain neurotransmitters, such as gamma-aminobutyric acid (GABA). Impairments in WM are seen in a range of psychiatric and neurological disorders, and there are currently no effective methods of remediating WM deficits. In this study, we analysed secondary outcome measures from a trial investigating the effects of multi-day rTMS on cognition. Participants received four days of 20 Hz rTMS to an individualised region of left parietal cortex in one week, and an individualised region of pre-supplementary motor area (pre-SMA) in a separate week. We assessed changes to WM function before and after each week of stimulation (N = 39), and changes to GABA concentration before and after stimulation in week one using MR spectroscopy (N = 18 per stimulation condition). We hypothesised that multi-day parietal rTMS would enhance WM and reduce GABA concentration, but this was not observed. Instead, we report some evidence of improved WM function and increased GABA concentration following pre-SMA rTMS, although this effect was variable across individuals. Additionally, we found that higher cardiorespiratory fitness was associated with greater WM improvement following pre-SMA stimulation. While there are a number of factors known to influence the response to rTMS, increasing cardiorespiratory fitness may provide a novel approach to enhance cognitive outcomes. Given the clinical utility of both exercise and rTMS, future studies are required to determine whether additive effects may be achieved when applied in tandem.

Left parietal tACS at alpha frequency induces a shift of visuospatial attention

BackgroundVoluntary shifts of visuospatial attention are associated with a lateralization of occipitoparietal alpha power (7-13Hz), i.e. higher power in the hemisphere ipsilateral and lower power contralateral to the locus of attention. Recent noninvasive neuromodulation studies demonstrated that alpha power can be experimentally increased using transcranial alternating current stimulation (tACS).Objective/HypothesisWe hypothesized that tACS at alpha frequency over the left parietal cortex induces shifts of attention to the left hemifield. However, spatial attention shifts not only occur voluntarily (endogenous), but also stimulus-driven (exogenous). In order to study the task-specificity of the potential effects of tACS on attentional processes, we administered three conceptually different spatial attention tasks.Methods36 healthy volunteers were recruited from an academic environment. In two seperate sessions, we applied either high-density tACS at 10Hz, or sham tACS, for 35-40 minutes to their left parietal cortex. We systematically compared performance on endogenous attention, exogenous attention, and stimulus detection tasks.ResultsIn the Endogenous attention task, we found a greater leftward bias in reaction times during left parietal 10Hz tACS as compared to sham. There were no stimulation effects in the exogenous attention or stimulus detection task.ConclusionThe study shows that high-density tACS at 10Hz can be used to modulate visuospatial attention performance. The tACS effect is task-specific, indicating that not all forms of attention are equally susceptible to the stimulation.

When the affordances disappear: Dynamical and computational explanations of optic ataxia

Two options fuel the debate on the cognitive processes underlying the perception of affordances. On the one hand, the ecological theory of affordance fits with the methodological assumptions of the dynamical systems theory of cognition. On the other hand, it is nowadays common to conceive the perception of affordances within a computational framework. This article defends the explanatory power of a computational approach and aims to extend the concept of affordance beyond the boundaries of the dynamical systems theory of cognition. For that purpose, I consider the case of patients suffering from optic ataxia, a condition in which some aspects of visual guidance over reaching with the hand are lost following a lesion in the left parietal cortex. Etiological considerations, indeed, reveal that a computational approach to the perception of affordances allows for an explanation of ataxic behavior that is not available to the dynamical systems theory.