RESUMEN
Brain regions that are involved in memory formation, particularly medial temporal lobe (MTL) structures and lateral prefrontal cortex (PFC), have been identified in adults, but not in children. We investigated the development of brain regions involved in memory formation in 49 children and adults (ages 8-24), who studied scenes during functional magnetic resonance imaging. Recognition memory for vividly recollected scenes improved with age. There was greater activation for subsequently remembered scenes than there was for forgotten scenes in MTL and PFC regions. These activations increased with age in specific PFC, but not in MTL, regions. PFC, but not MTL, activations correlated with developmental gains in memory for details of experiences. Voxel-based morphometry indicated that gray matter volume in PFC, but not in MTL, regions reduced with age. These results suggest that PFC regions that are important for the formation of detailed memories for experiences have a prolonged maturational trajectory.
Asunto(s)
Envejecimiento/fisiología , Mapeo Encefálico , Encéfalo/fisiología , Memoria/fisiología , Adolescente , Adulto , Encéfalo/crecimiento & desarrollo , Niño , Femenino , Lateralidad Funcional , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Pruebas Neuropsicológicas , Estimulación LuminosaRESUMEN
Behavioral studies with amnesic patients and imaging studies with healthy adults have suggested that medial temporal lobe (MTL) structures known to be essential for long-term declarative memory (LTM) may also be involved in the maintenance of information in working memory (WM). To examine whether MTL structures are involved in WM maintenance for faces, and the nature of that involvement, WM and LTM for faces were examined in normal participants via functional magnetic resonance imaging (fMRI) and in amnesic patients behaviorally. In Experiment 1, participants were scanned while performing a WM task in which they determined if two novel faces, presented 7 s apart, were the same or different. Later, participants' LTM for the faces they saw during the WM task was measured in an unexpected recognition test. During WM maintenance, the hippocampus was activated bilaterally, and there was greater activation during maintenance for faces that were later remembered than faces later forgotten. A conjunction analysis revealed overlap in hippocampal activations across WM maintenance and LTM contrasts, which suggested that the same regions were recruited for WM maintenance and LTM encoding. In Experiment 2, amnesic and control participants were tested on similar WM and LTM tasks. Amnesic patients, as a group, had intact performance with a 1-s maintenance period, but were impaired after a 7-s WM maintenance period and on the LTM task. Thus, parallel neuroimaging and lesion designs suggest that the same hippocampal processes support WM maintenance, for intervals as short as 7 s, and LTM for faces.
Asunto(s)
Amnesia/fisiopatología , Síndrome de Korsakoff/fisiopatología , Imagen por Resonancia Magnética , Memoria a Corto Plazo/fisiología , Recuerdo Mental/fisiología , Lóbulo Temporal/fisiopatología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Amnesia/patología , Cara , Femenino , Humanos , Síndrome de Korsakoff/patología , Masculino , Persona de Mediana Edad , Estimulación Luminosa , Lóbulo Temporal/patologíaRESUMEN
We aimed to discover the neural correlates of subjective judgments of learning-whereby participants judge whether current experiences will be subsequently remembered or forgotten-and to compare these correlates to the neural correlates of actual memory formation. During event-related functional magnetic resonance imaging, participants viewed 350 scenes and predicted whether they would remember each scene in a later recognition-memory test. Activations in the medial temporal lobe were associated with actual encoding success (greater activation for objectively remembered than forgotten scenes), but not with predicted encoding success (activations did not differ for scenes predicted to be remembered versus forgotten). Conversely, activations in the ventromedial prefrontal cortex were associated with predicted but not actual encoding success, and correlated with individual differences in the accuracy of judgments of learning. Activations in the lateral and dorsomedial prefrontal cortex were associated with both actual and predicted encoding success. These findings indicate specific dissociations and associations between the neural systems that mediate actual and predicted memory formation.