Author Correction: Retrieval of retrained and reconsolidated memories are associated with a distinct neural network.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Retrieval of retrained and reconsolidated memories are associated with a distinct neural network.

Consolidated memories can persist from a single day to years, and persistence is improved by retraining or retrieval-mediated plasticity. One retrieval-based way to strengthen memory is the reconsolidation process. Strengthening occurs simply by the presentation of specific cues associated with the original learning. This enhancement function has a fundamental role in the maintenance of memory relevance in animals everyday life. In the present study, we made a step forward in the identification of brain correlates imprinted by the reconsolidation process studying the long-term neural consequences when the strengthened memory is stable again. To reach such a goal, we compared the retention of paired-associate memories that went through retraining process or were labilizated-reconsolidated. Using functional magnetic resonance imaging (fMRI), we studied the specific areas activated during retrieval and analyzed the functional connectivity of the whole brain associated with the event-related design. We used Graph Theory tools to analyze the global features of the network. We show that reconsolidated memories imprint a more locally efficient network that is better at exchanging information, compared with memories that were retrained or untreated. For the first time, we report a method to elucidate the neural footprints associated with a relevant function of memory reconsolidation.

Differential Left Hippocampal Activation during Retrieval with Different Types of Reminders: An fMRI Study of the Reconsolidation Process.

Consolidated memories return to a labile state after the presentation of cues (reminders) associated with acquisition, followed by a period of stabilization (reconsolidation). However not all cues are equally effective in initiating the process, unpredictable cues triggered it, predictable cues do not. We hypothesize that the different effects observed by the different reminder types on memory labilization-reconsolidation depend on a differential neural involvement during reminder presentation. To test it, we developed a declarative task and compared the efficacy of three reminder types in triggering the process in humans (Experiment 1). Finally, we compared the brain activation patterns between the different conditions using functional magnetic resonance imaging (fMRI) (Experiment 2). We confirmed that the unpredictable reminder is the most effective in initiating the labilization-reconsolidation process. Furthermore, only under this condition there was differential left hippocampal activation during its presentation. We suggest that the left hippocampus is detecting the incongruence between actual and past events and allows the memory to be updated.

Inclusión de técnicas imagenológicas en la planificación neuroquirúrgica: integración de equipos multidisciplinarios / Inclusion of imaging techniques in neurosurgical planning: integration of multidisciplinary teams

Introducción: El tratamiento quirúrgico de las epilepsias consiste en lograr la resección del área lesional o epileptógena minimizando a la vez el déficit neurológico postquirúrgico. Las neuroimágenes se han constituido en una poderosa herramienta diagnóstica. El procesamiento de las mismas logran proveer relación topográfica entre la lesión, el área epileptogénica primaria y las áreas funcionales importantes de manera no invasiva. Objetivos: Estudiar la utilidad de incluir diferentes técnicas de imágenes en la evaluación prequirúrgica, planificación y resección quirúrgica de epilepsias. Materiales y Métodos: Se estudiaron 8 pacientes con diagnóstico de epilepsia con diversas técnicas imagenológicas, en resonador 3T y en tomógrafo helicoidal de 64 canales. Las imágenes fueron post-procesadas, corregistradas, fusionadas e incorporadas en el sistema de neuronavegación. La información resultante fue estudiada por un equipo multidisciplinario de físicos médicos y neurocirujanos. Resultados: Los casos presentados muestran que la incorporación e integración de las técnicas de imágenes facilitan la comprensión anatómica, metabólica y funcional del área lesional /epileptogénica y el tejido circundante. La cirugía guiada por imágenes colabora en la mejora de las limitaciones de los métodos “gold standard”, como son la electrocorticografía y la estimulación cortical eléctrica directa, disminuyendo la invasividad, el tamaño de la craneotomía, aumentando el área de resección de la lesión y brindando mayor seguridad en los resultados postquirúrgicos.