Interferencia de la información léxica sobre la identificación de fonemas durante una tarea de decisión fonológica / Lexical information interference in phonemic recognition during a phonological decision task

A partir de estudios con potenciales relacionados a eventos en tareas de decisión fonológica (DF) o léxica (DL), se ha propuesto que el procesamiento auditivo del lenguaje es de tipo serial con interacciones tardías entre los módulos fonológico, sintáctico y semántico. Este trabajo intentó valorar si existía una interferencia entre el procesamiento fonológico y semántico durante la DL y DF de sintagmas nominales utilizando un artículo definido en concordancia con un sustantivo. A fin de examinar esto, se presentaron 180 estímulos auditivos a un grupo de participantes, y se les pidió que realizaran una tarea de DL y una de decisión DF; 60 estímulos utilizaron palabras de la lengua, 60 con una vocal alterada en el sustantivo que generaba una pseudopalabra (PSP1), y 60 con una sílaba traslocada en el sustantivo para generar otro tipo de pseudopalabra (PSP2). Se registraron 10 participantes hispanohablantes adultos sin padecimientos neurológicos ni psiquiátricos. Se encontró que los participantes se equivocaron más al identificar las PSP1 que las PSP2 en la tarea de DL. No se encontraron diferencias en el componente N400 durante DL. En la tarea de DF, se encontró que el N100 incrementó su amplitud ante la presentación de palabras. Estos hallazgos apuntan a que la información léxica interfiere con la fase de procesamiento fonológico y cuestiona el modelo de procesamiento serial del lenguaje.

Experiments using event-related potentials during phonological decision (PD) and lexical decision (LD) tasks have suggested that auditory language processing occurs in a serial fashion, with late interactions amongst the phonological, syntactic and semantic modules. This paper sought to assess the existence of interference between phonological and semantic processing during LD and PD in nominal phrases, by using a definite article to match a noun. In order to examine this, 180 auditory stimuli were presented to a group of participants, and they were asked to perform a LD and a PD task. Sixty auditory stimuli included a noun that generated a pseudo-word (PSP1), and 60 others included a misplaced syllable within the noun so as to generate another type of pseudo-word (PSP2). Ten adult Spanish speakers without any neurological or psychiatric disorders volunteered to take part in the experiment. Participants were found to make more mistakes when identifying PSP1 than PSP2 during the LD task. There were no significant differences in the N400 component during LD. As for the PD task, it was found that N100 increased in amplitude when words were presented. These findings go to show that lexical information interferes with the phonological processing phase, and questions the serial model of language processing.

Performance of the Towers of Hanoi task and cortical electroencephalographic power changes associated with infancy, adolescence, and early adulthood.

The executive functions, which depend on the adequate maturation and functioning of the prefrontal cortex and its connection to posterior zones, follow a process of development as age increases. This work studied changes in the absolute power (AP) of EEG activity recorded in the prefrontal and parietal areas during the performance of the Tower of Hanoi task in children, adolescents, and young adults. Three groups of healthy male subjects such as G1, 11-13; G2, 18-20; and G3, 26-30, years of age were recorded at the F3, F4, P3, and P4 derivations under two conditions: basal and performance of the Towers of Hanoi task. The majority of subjects in G1 failed to complete the task in the allotted time (7 min), while those in G2 and G3 were able to resolve the task quickly and efficiently. During the Towers of Hanoi task, G1 showed an increase of AP in the delta band only in the frontal areas, with a decrease in the alpha1 and alpha2 sub-bands only at the parietal derivations, while G2 and G3 were characterized by an increase of AP in the delta band and a decreased AP in the alpha1 and alpha2 sub-bands in all derivations. These data demonstrate that during the performance of the Towers of Hanoi task, the prefrontal and parietal areas show a characteristic EEG pattern in relation to age. It is probable that the AP patterns obtained in G2 and G3 are associated with the functional changes at cortical levels that adolescents and early adults require to achieve an adequate and fast performance of the Towers of Hanoi task.

Prefrontal-parietal correlation during performance of the towers of Hanoi task in male children, adolescents and young adults.

Potential age differences in the electroencephalographic (EEG) correlation (r) between the prefrontal and parietal cortices during performance of the Tower of Hanoi task were studied. In three groups of healthy males (G1, 11-13; G2, 18-20, and G3, 26-30, years of age) EEGs were recorded at baseline and during performance of the Tower of Hanoi task. The parameters of the task showed no significant differences among groups, though the majority of younger subjects failed to complete it. The G1 group showed increases only in the interparietal r. The G2 group showed an increased interhemispheric and intrahemispheric r in almost all frequency bands, while the r in G3 increased only in selected frequency bands in the right hemisphere. These findings demonstrate that the functional coupling between these two cortices shows a characteristic pattern during performance of the Hanoi task that, while specific to each age group, was not associated with the successful performance of the task.

Orbitofrontal Cortex Inactivation Impairs Early Reversal Learning in Male Rats During a Sexually Motivated Task

This study analyzes whether inactivation of the orbitofrontal cortex (OFC) affects early discrimination or reversal learning during a T maze motivated task. Male rats received saline solution or one doses of tetrodotoxin (TTX) bilaterally into the OFC, and were permitted to have an intromission with a receptive female to induce a sexually motivated state. Discrimination and reversal sessions consisted of seven trials each to accomplish the non-overtrained condition. Each arm of the T maze was associated to different external cues. Subjects were sexually reinforced whenever they reached the receptive female box, and returned to the start-box if not. Spontaneous motor activity was not altered. Rats with OFC inactivated did not present alteration during discrimination. Males with higher doses of TTX had a deficit in the number of correct responses and increased number of trials without response during reversal learning. These data agrees with other studies and indicates that an intact OFC is essential for the adequate manifestation of reversal learning during its early phase in motivated tasks. However, disagrees with other findings about early perseverative responses, pointing out to a critical role of this structure in enhancing performance through incentive value re-assignment of predicted outcome cues (AU)

El objetivo de este estudio fue investigar si la inactivación de la corteza orbitofrontal (COF) afecta el aprendizaje de discriminación y/o de inversión, en su etapa temprana, durante la resolución de un laberinto T por ratas macho, utilizando como incentivo una interacción copulatoria con una hembra receptiva. Las ratas experimentales fueron infundidas con solución salina o una dosis de tetrodotoxina (TTX) bilateralmente en la COF. Luego de esto, se les permitió tener una intromisión con una hembra receptiva para inducirles un estado sexualmente motivado. Las sesiones de discriminación y de inversión consistieron en siete ensayos cada una para mantener al sujeto en un estado motivado y en la condición de aprendizaje inicial. Cada brazo del laberinto fue asociado a diferentes señales externas al mismo. Los sujetos fueron reforzados con una interacción sexual cada vez que llegaban al compartimento donde se encontraba una hembra receptiva, y eran retornados a la caja inicial cuando no lo hacían. Los sujetos que recibieron TTX no presentaron alteración en la evaluación de la conducta motora espontánea en campo abierto. Tampoco se encontró alteración significativa en las respuestas correctas durante la fase de discriminación. Las ratas que recibieron la dosis más alta de TTX presentaron un deterioro en el número de respuestas correctas y un incremento significativo en el número de ensayos sin respuesta durante la fase de inversión. Estos datos coinciden con los de estudios que señalan que una COF intacta es crítica para la adecuada ejecución durante la fase inicial del aprendizaje de inversión en tareas motivadas, aunque difieren de la mayoría de informes que encuentran un aumento de la respuesta perseverativa durante la etapa inicial de la inversión. Estos hallazgos parecen apoyar el probable papel crítico que juega la COF en la reasignación de valor incentivo de los estímulos que sirven de señal para la correcta ejecución de tareas motivadas (AU)