RESUMEN

The parietal lobe, constituting approximately 20% of the human brain, comprises two main regions: the somatosensory cortex and the posterior parietal cortex. The former is responsible for receiving and processing information from the organism itself or its external environment, while the latter performs concurrent summaries and higher cognitive functions. The present study seeks to integrate modern research findings with Luria's previous discoveries in order to gain a nuanced understanding of the roles assigned to the parietal lobe as well as its lateralization differences.

RESUMEN

Visuospatial attention is a cognitive skill essential to the performance of air traffic control activities. We evaluated the effect of an anodic session of transcranial low-intensity direct current stimulation (tDCS) right parietal associated with cognitive training of visuospatial attention of 21 air traffic controllers. Within-subject designs were used, with all volunteers undergoing two tDCS sessions; an experimental (2 mA anodic) and control (sham) performed concomitantly with the cognitive training (2-Back). Visuospatial performance was measured using the Attention Network Test for Interactions and Vigilance pre- and post-intervention. The results indicate that after an active parietal tDCS session, the ATCOs showed faster responses, but not more accurate, for visuospatial attention in its aspects of orientation and reorientation. This result was significant when comparing baseline and post-tests in the active tDCS group. Comparing the post-tests between the tDCS active and sham groups, it is possible to infer a trend of improvement in the results based on faster and more accurate responses, which suggests a possible refinement of the ATCO's attentional orientation. However, this population may eventually have reached a plateau in the performance of this skill. From the analysis of the results we arrive at the following hypotheses: (I) the increase in cortical excitability mediated by anodic tDCS frequently recorded may not be accompanied by improvements in behavioural measures; (II) the interaction between anodic tDCS with another event of increased excitability-execution of a cognitive task, may have hindered the occurrence of neuroplasticity; (III) the air traffic control activity may be associated with a high level of attention, which may have contributed to a ceiling effect for the development of this skill; (IV) online assessments may be more relevant to identify acute effects; (V) repeated sessions may be more efficient to find cumulative effects; (VI) the analysis of interactions between attentional networks can contribute to the study of visuospatial attention; (VII) tDCS protocols aimed at ATCO need to consider the specifics of this audience, such as circadian rhythm and sleep and fatigue conditions.

Asunto(s)

Excitabilidad Cortical , Estimulación Transcraneal de Corriente Directa , Excitabilidad Cortical/fisiología , Fatiga , Humanos , Plasticidad Neuronal , Estimulación Transcraneal de Corriente Directa/métodos

RESUMEN

Abstract. Objective. This study characterized the electroencephalographic correlation (rEEG) between prefrontal and parietalcortices in young men while solving logical-mathematical problems after 18 sessions of cognitive training. Method. Two training groups were formed: one trained with gradually increased complexity (CT), the other with no increase in complexity (ST). Results. CT had a greater number of correct responses in the post-training evaluation than ST and showed a higher correlation between the left frontopolar-parietal cortices in almost all EEG bands, and between the dorsolateral-parietal cortices in the alpha1 band while solving math problems post-training. Results suggest that major functional synchronization between the left prefrontal and parietal cortices plays an important role in improving mathematical problem-solving after cognitive training.

---

Resumen Objetivo. El presente estudio caracteriza la correlación electroencefalográfica (rEEG) entre las cortezas prefrontal y parietal en hombres jóvenes durante la resolución de problemas lógico-matemáticos después de 18 sesiones de entrenamiento cognitivo. Método. Se formaron dos grupos de entrenamiento: uno entrenado con un incremento gradual de complejidad (CT) y el otro sin incremento de complejidad (ST). Resultados. El grupo CT presentó un mayor número de respuestas correctas que el grupo ST en la evaluación post entrenamiento, a su vez mostró un incremento en la correlación entre las cortezas frontopolar y parietal izquierdas en la mayoría de las bandas, así como entre las cortezas dorsolateral y parietal en la banda alfa1 durante la resolución de problemas posterior al entrenamiento. Los resultados sugieren que el incremento en la sincronización funcional entre las cortezas prefrontal y parietal izquierdas juega un rol importante en la resolución de problemas matemáticos después del entrenamiento cognitivo.

Asunto(s)

Humanos , Masculino , Adulto , Electroencefalografía , Entrenamiento Cognitivo , Lógica , Matemática , México

RESUMEN

The ability to anticipate events and execute motor commands prior to a sensory event is an essential capability for human's everyday life. This implicitly learned anticipatory behavior depends on the past performance of repeated sensorimotor interactions timed with external cues. This kind of predictive behavior has been shown to be compromised in neurological disorders such as Huntington disease (HD), in which neural atrophy includes key cortical and basal ganglia regions. To investigate the neural basis of the anticipatory behavioral deficits in HD we used a predictive-saccade paradigm that requires predictive control to generate saccades in a metronomic temporal pattern. This is ideal because the integrity of the oculomotor network that includes the striatum and prefrontal, parietal, occipital and temporal cortices can be analyzed using structural MRI. Our results showed that the HD patients had severe predictive saccade deficits (i.e., an inability to reduce saccade reaction time in predictive condition), which are accentuated in patients with more severe motor deterioration. Structural imaging analyses revealed that these anticipatory deficits correlated with grey-matter atrophy in frontal, parietal-occipital and striatal regions. These findings indicate that the predictive saccade control deficits in HD are related to an extended cortico-striatal atrophy. This suggests that eye movement measurement could be a reliable marker of the progression of cognitive deficits in HD.

Asunto(s)

Atrofia/patología , Trastornos del Conocimiento/patología , Enfermedad de Huntington/patología , Aprendizaje/fisiología , Adulto , Anciano , Atrofia/fisiopatología , Encéfalo/patología , Trastornos del Conocimiento/fisiopatología , Femenino , Sustancia Gris/patología , Humanos , Enfermedad de Huntington/fisiopatología , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Vías Nerviosas/patología , Tiempo de Reacción

RESUMEN

The low-frequency repetitive transcranial magnetic stimulation (rTMS) application has been associated with changes in cognitive processes embedded during time perception tasks. Although several studies have investigated the influence of neuromodulation on time perception, the effect of the 1-Hz rTMS application on the superior parietal cortex is not clearly understood. This study analyzes the effect of the low-frequency rTMS on time estimation when applied in the parietal medial longitudinal fissure. For the proposed study, 20 subjects were randomly selected for a crossover study with two conditions (sham and 1 Hz). Our findings reveal that participant underestimate 1-s time interval and overestimate 4-s and 9-s time intervals after 1-Hz rTMS (p ≤ 0.05). We conclude that the 1-Hz rTMS in the parietal medial longitudinal fissure delays short interval and speed up long time intervals. This could be due to the effect of parietal inhibition on the attentional level and working memory functions during time estimation.

Asunto(s)

Lóbulo Parietal/fisiología , Percepción del Tiempo/fisiología , Estimulación Magnética Transcraneal , Adulto , Estudios Cruzados , Femenino , Humanos , Masculino , Adulto Joven

RESUMEN

Methylphenidate produces its effects via actions on cortical areas involved with attention and working memory, which have a direct role in time estimation judgment tasks. In particular, the prefrontal and parietal cortex has been the target of several studies to understand the effect of methylphenidate on executive functions and time interval perception. However, it has not yet been studied whether acute administration of methylphenidate influences performance in time estimation task and the changes in alpha band absolute power in the prefrontal and parietal cortex. The current study investigates the influence of the acute use of methylphenidate in both performance and judgment in the time estimation interpretation through the alpha band absolute power activity in the prefrontal and parietal cortex. This is a double-blind, crossover study with a sample of 32 subjects under control (placebo) and experimental (methylphenidate) conditions with absolute alpha band power analysis during a time estimation task. We observed that methylphenidate does not influence task performance (p > 0.05), but it increases the time interval underestimation by over 7 s (p < 0.001) with a concomitant decrease in absolute alpha band power in the ventrolateral prefrontal cortex and dorsolateral prefrontal cortex and parietal cortex (p < 0.001). Acute use of methylphenidate increases the time interval underestimation, consistent with reduced accuracy of the internal clock mechanisms. Furthermore, acute use of methylphenidate influences the absolute alpha band power over the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, and parietal cortex.

Asunto(s)

Ritmo alfa/efectos de los fármacos , Estimulantes del Sistema Nervioso Central/farmacología , Juicio/efectos de los fármacos , Metilfenidato/farmacología , Lóbulo Parietal/efectos de los fármacos , Corteza Prefrontal/efectos de los fármacos , Desempeño Psicomotor/efectos de los fármacos , Tiempo de Reacción/efectos de los fármacos , Percepción del Tiempo/efectos de los fármacos , Adulto , Estimulantes del Sistema Nervioso Central/administración & dosificación , Estimulantes del Sistema Nervioso Central/efectos adversos , Estudios Cruzados , Método Doble Ciego , Humanos , Masculino , Metilfenidato/administración & dosificación , Metilfenidato/efectos adversos , Adulto Joven

RESUMEN

In aiming movements the limb position drifts away from the defined target after some trials without visual feedback, a phenomenon defined as proprioceptive drift (PD). There are no studies investigating the association between the posterior parietal cortex (PPC) and PD in aiming movements. Therefore, cathodal and sham transcranial direct current stimulation (tDCS) were applied to the left PPC concomitantly with the performance of movements with or without vision. Cathodal tDCS applied without vision produced a higher level of PD and higher rates of drift accumulation while it decreased peak velocity and maintained the number of error corrections, not affecting movement amplitude. The proprioceptive information seems to produce an effective reference to movement, but with PPC stimulation it causes a negative impact on position.

Asunto(s)

Lóbulo Parietal/fisiología , Propiocepción/fisiología , Estimulación Transcraneal de Corriente Directa , Adolescente , Adulto , Fenómenos Biomecánicos/fisiología , Retroalimentación Sensorial/fisiología , Femenino , Humanos , Masculino , Desempeño Psicomotor/fisiología , Adulto Joven

RESUMEN

AIM OF THE STUDY: Previous studies have shown that several cortical regions are involved in temporal tasks in multiple timescales. However, the hemispheric predominance of the dorsolateral prefrontal cortex (DLPFC) during time reproduction after repetitive low-frequency transcranial magnetic stimulation (rTMS) is relatively unexplored. Here, we study the effects of 1 Hz rTMS and sham stimulation applied medially over the superior parietal cortex (SPC) on the DLPFC alpha and beta band asymmetry and on time reproduction. MATERIALS AND METHODS: For this purpose, we have combined rTMS with electroencephalography in 20 healthy subjects who performed the time reproduction task in two conditions (sham and 1 Hz). RESULTS: The worst performance was observed in sham and 1Hz conditions for longer time intervals (p < .05), with the 1Hz condition subjects sub-reproducing the time interval, closer to the target interval (p < .05). The right DLPFC hemispheric predominance was found in both conditions, but after low-frequency rTMS, the right hemisphere predominance increased in the 1Hz condition (p < .05). CONCLUSIONS: Results of this study suggest that rTMS applied over the SPC influences time interval interpretation and the DLPFC functions. Future studies would explore the effects of the rTMS application to other cortical areas, and study how it influences time interval interpretation.

Asunto(s)

Dominancia Cerebral , Lóbulo Parietal/fisiología , Corteza Prefrontal/fisiología , Percepción del Tiempo/fisiología , Estimulación Magnética Transcraneal/métodos , Adulto , Ritmo alfa/fisiología , Ritmo beta/fisiología , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Adulto Joven

RESUMEN

Telomere length (TL) is a biomarker of cell aging, and its shortening has been linked to several age-related diseases. In Alzheimer's disease (AD), telomere shortening has been associated with neuroinflammation and oxidative stress. The majority of studies on TL in AD were based on leucocyte DNA, with little information about its status in the central nervous system. In addition to other neuroprotective effects, lithium has been implicated in the maintenance of TL. The present study aims to determine the effect of chronic lithium treatment on TL in different regions of the mouse brain, using a triple-transgenic mouse model (3xTg-AD). Eighteen transgenic and 22 wild-type (Wt) male mice were treated for eight months with chow containing 1.0 g (Li1) or 2.0 g (Li2) of lithium carbonate/kg, or standard chow (Li0). DNA was extracted from parietal cortex, hippocampus and olfactory epithelium and TL was quantified by real-time PCR. Chronic lithium treatment was associated with longer telomeres in the hippocampus (Li2, p = 0.0159) and in the parietal cortex (Li1, p = 0.0375) of 3xTg-AD compared to Wt. Our findings suggest that chronic lithium treatment does affect telomere maintenance, but the magnitude and nature of this effect depend on the working concentrations of lithium and characteristics of the tissue. This effect was observed when comparing 3xTg-AD with Wt mice, suggesting that the presence of AD pathology was required for the lithium modulation of TL.

Asunto(s)

Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/patología , Antipsicóticos/uso terapéutico , Hipocampo/efectos de los fármacos , Compuestos de Litio/uso terapéutico , Lóbulo Parietal/efectos de los fármacos , Homeostasis del Telómero/efectos de los fármacos , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/genética , Precursor de Proteína beta-Amiloide/genética , Animales , Antipsicóticos/sangre , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutación/genética , Lóbulo Parietal/metabolismo , Presenilina-1/genética , Proteínas tau/genética

RESUMEN

In ERP studies of cognitive processes during attentional tasks, the cue signals containing information about the target can increase the amplitude of the parietal cue P3 in relation to the 'neutral' temporal cue, and reduce the subsequent target P3 when this information is valid, i.e. corresponds to the target's attributes. The present study compared the cue-to-target P3 ratios in neutral and visuospatial cueing, in order to estimate the contribution of valid visuospatial information from the cue to target stages of the task performance, in terms of cognitive load. The P3 characteristics were also correlated with the results of individuals' performance of the visuospatial tasks, in order to estimate the relationship of the observed ERP with spatial reasoning. In 20 typically developing boys, aged 10-13 years (11.3±0.86), the intelligence quotient (I.Q.) was estimated by the Block Design and Vocabulary subtests from the WISC-III. The subjects performed the Attentional Network Test (ANT) accompanied by EEG recording. The cued two-choice task had three equiprobable cue conditions: No cue, with no information about the target; Neutral (temporal) cue, with an asterisk in the center of the visual field, predicting the target onset; and Spatial cues, with an asterisk in the upper or lower hemifield, predicting the onset and corresponding location of the target. The ERPs were estimated for the mid-frontal (Fz) and mid-parietal (Pz) scalp derivations. In the Pz, the Neutral cue P3 had a lower amplitude than the Spatial cue P3; whereas for the target ERPs, the P3 of the Neutral cue condition was larger than that of the Spatial cue condition. However, the sums of the magnitudes of the cue and target P3 were equal in the spatial and neutral cueing, probably indicating that in both cases the equivalent information processing load is included in either the cue or the target reaction, respectively. Meantime, in the Fz, the analog ERP components for both the cue and target stimuli did not depend on the cue condition. The results show that, in the parietal site, the spatial cue P3 reflects the processing of visuospatial information regarding the target position. This contributes to the subsequent "decision-making", thus reducing the information processing load on the target response, which is probably reflected in the lower P3. This finding is consistent with the positive correlation of parietal cue P3 with the individual's ability to perform spatial tasks as scored by the Block Design subtest.

Asunto(s)

Atención , Señales (Psicología) , Potenciales Relacionados con Evento P300 , Lóbulo Parietal/fisiología , Procesamiento Espacial , Percepción Visual , Adolescente , Niño , Electroencefalografía , Humanos , Masculino

RESUMEN

Cebus monkeys stand out from other New World monkeys by their ability to perform fine hand movements, and by their spontaneous use of tools in the wild. Those behaviors rely on the integration of somatosensory information, which occurs in different areas of the parietal cortex. Although a few studies have examined and parceled the somatosensory areas of the cebus monkey, mainly using electrophysiological criteria, very little is known about its anatomical organization. In this study we used SMI-32 immunohistochemistry, myelin, and Nissl stains to characterize the architecture of the parietal cortical areas of cebus monkeys. Seven cortical areas were identified between the precentral gyrus and the anterior bank of the intraparietal sulcus. Except for areas 3a and 3b, distinction between different somatosensory areas was more evident in myelin-stained sections and SMI-32 immunohistochemistry than in Nissl stain, especially for area 2 and subdivisions of area 5. Our results show that cebus monkeys have a relatively complex somatosensory cortex, similar to that of macaques and humans. This suggests that, during primate evolution, the emergence of new somatosensory areas underpinned complex manual behaviors in most Old World simians and in the New World cebus monkey. J. Comp. Neurol. 524:1399-1423, 2016. © 2015 Wiley Periodicals, Inc.

Asunto(s)

Mapeo Encefálico , Miembro Anterior/fisiología , Destreza Motora/fisiología , Movimiento/fisiología , Corteza Somatosensorial/fisiología , Comportamiento del Uso de la Herramienta/fisiología , Animales , Cebus , Estimulación Eléctrica , Femenino , Imagenología Tridimensional , Masculino , Vaina de Mielina/metabolismo , Proteínas de Neurofilamentos/metabolismo

RESUMEN

This investigation was undertaken in order to quantify the effects of early polysensorial enrichment on the development of cortical pyramids, located in the parietal cortex of rats simultaneously submitted to protein-energy undernutrition. A short period of stimulation during suckling significantly decreases the cellular density in the cortical plate (phylogenetic-ontogenetic evolutionary index). Results suggest that the cerebral cortex develops according to a sophisticated neuronal network, which exhibits a notable degree of structural specificity, regulated by genetic and environmental clues. The most obvious prediction is that environmental influences are probably transduced as a structural expression in the developing parietal cortical plate.

---

La presente investigación se realizó con la finalidad de cuantificar los efectos del enriquecimiento polisensorial temprano sobre el desarrollo de células piramidales de la corteza parietal, en ratas que simultáneamente fueron sometidas a desnutrición calórico-proteica. Un breve periodo de estimulación durante el periodo de lactancia disminuyó significativamente la densidad celular en la placa cortical (índice evolutivo filogenético-ontogenético). Los resultados sugieren que la corteza cerebral se desarrolla de acuerdo con una red neuronal altamente sofisticada, la cual exhibe un notable grado de especificidad estructural regulada por claves genéticas y ambientales. La predicción más obvia es que las influencias ambientales son probablemente traducidas como expresión estructural en la placa cortical parietal.

Asunto(s)

Animales , Ratas , Lóbulo Parietal/anatomía & histología , Lóbulo Parietal/crecimiento & desarrollo , Desnutrición Proteico-Calórica , Ambiente , Ratas Sprague-Dawley

RESUMEN

In the so-called McGurk illusion, when the synchronized presentation of the visual stimulus /ga/ is paired with the auditory stimulus /ba/, people in general hear it as /da/. Multisensory integration processing underlying this illusion seems to occur within the Superior Temporal Sulcus (STS). Herein, we present evidence demonstrating that bilateral cathodal transcranial direct current stimulation (tDCS) of this area can decrease the McGurk illusion-type responses. Additionally, we show that the manipulation of this audio-visual integrated output occurs irrespective of the number of eye-fixations on the mouth of the speaker. Bilateral anodal tDCS of the Parietal Cortex also modulates the illusion, but in the opposite manner, inducing more illusion-type responses. This is the first demonstration of using non-invasive brain stimulation to modulate multisensory speech perception in an illusory context (i.e., both increasing and decreasing illusion-type responses to a verbal audio-visual integration task). These findings provide clear evidence that both the superior temporal and parietal areas contribute to multisensory integration processing related to speech perception. Specifically, STS seems fundamental for the temporal synchronization and integration of auditory and visual inputs. For its part, posterior parietal cortex (PPC) may adjust the arrival of incoming audio and visual information to STS thereby enhancing their interaction in this latter area.

RESUMEN

The posterior parietal cortex (PPC) was long viewed as just involved in the perception of spatial relationships between the body and its surroundings and of movements related to them. In recent years the PPC has been shown to participate in many other cognitive processes, among which working memory and the consolidation and retrieval of episodic memory. The neurotransmitter and other molecular processes involved have been determined to a degree in rodents. More research will no doubt determine the extent to which these findings can be extrapolated to primates, including humans. In these there appears to be a paradox: imaging studies strongly suggest an important participation of the PPC in episodic memory, whereas lesion studies are much less suggestive, let alone conclusive. The data on the participation of the PPC in episodic memory so far do not permit any conclusion as to what aspect of consolidation and retrieval it handles in addition to those dealt with by the hippocampus and basolateral amygdala, if any.

RESUMEN

Repetitive Magnetic Stimulation (rTMS) has shown to modify the excitability of targeted cortical regions in animals and humans, thus transiently altering the efficiency of neural projections within extended brain networks. Adequate processing and behavioral output depend on a given ‘state’ of functional interactions between cortical and subcortical nodes within this network. We applied rTMS trains targeted at the visuoparietal (VP) cortex, which is a crucial cortical node of an extended visuo-spatial neural network, in both, intact (n=2) and injured cats (n=2) with unilateral ablation of the VP region. All four intact cats were intensively trained in a set of visuo-spatial tasks consisting in the detection and localization of moving or static targets. In two of these cats, a 50 mm circular coil was centered on the left VP cortex and Sham or real rTMS was delivered during 20 minutes at 1 Hz. Real but not Sham rTMS significantly increased the number of errors in orienting responses towards static but not moving targets, presented at the contralateral visual hemifield (38±4%; and 48±3% p<0.05 vs. pre rTMS), whereas no increase respect to baseline was observed for ipsilateral targets (5±2%; 2±1%; n.s). Performance went back to baseline error levels 45 minutes after the end of the stimulation (4±2; 6±1%). In 2 other animals, the right or left parietal and primary visual cortex was surgically removed, generating a Daily stimulation with 1 Hz rTMS on the intact VP region resulted in a progressive reduction of detection¬orienting mistakes to moving but not static stimuli (down to 34±5% and 28±4% errors; p<0.05). We conclude that rTMS is able to interact with brain networks in both ways, transiently disrupting visuo-spatial processing in normal animals, and also canceling spatial neglect generated by lesions of the same areas. It constitutes, thus, a non-invasive ‘surgery-less’ method to manipulate brain activity and promote recovery after injuries.

Asunto(s)

Gatos , Corteza Cerebral , Neurología , Estimulación Magnética Transcraneal