A large body of evidence has shown that treatments that interfere with memory consolidation become ineffective when animals are subjected to an intense learning experience; this effect has been ...observed after systemic and local administration of amnestic drugs into several brain areas, including the striatum. However, the effects of amnestic treatments on the process of extinction after intense training have not been studied. Previous research demonstrated increased spinogenesis in the dorsomedial striatum, but not in the dorsolateral striatum after intense training, indicating that the dorsomedial striatum is involved in the protective effect of intense training. To investigate this issue, male Wistar rats, previously trained with low, moderate, or high levels of foot shock, were used to study the effect of tetrodotoxin inactivation of dorsomedial striatum on memory consolidation and subsequent extinction of inhibitory avoidance. Performance of the task was evaluated during seven extinction sessions. Tetrodotoxin produced a marked deficit of memory consolidation of inhibitory avoidance trained with low and moderate intensities of foot shock, but normal consolidation occurred when a relatively high foot shock was used. The protective effect of intense training was long-lasting, as evidenced by the high resistance to extinction exhibited throughout the extinction sessions. We discuss the possibility that increased dendritic spinogenesis in dorsomedial striatum may underly this protective effect, and how this mechanism may be related to the resilient memory typical of post-traumatic stress disorder (PTSD).
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Retrieval of moderate training induces mushroom spinogenesis in dorsal striatum.•Retrieval of strong training increases mushroom spinogenesis in dorsal striatum.•Retrieval reduces number of thin ...spines in dorsal striatum.•Spinogenesis in accumbens was due to the aversive stimulation, not to retrieval.
In marked contrast to the ample literature showing that the dorsal striatum is engaged in memory consolidation, little is known about its involvement in memory retrieval. Recent findings demonstrated significant increments in dendritic spine density and mushroom spine counts in dorsal striatum after memory consolidation of moderate inhibitory avoidance (IA) training; further increments were found after strong training. Here, we provide evidence that in this region spine counts were also increased as a consequence of retrieval of moderate IA training, and even higher mushroom spine counts after retrieval of strong training; by contrast, there were fewer thin spines after retrieval. Similar changes in mushroom and thin spine populations were found in the ventral striatum (nucleus accumbens), but they were related to the aversive stimulation and not to memory retrieval. These results suggest that memory retrieval is a dynamic process which produces neuronal structural plasticity that might be necessary for maintaining or strengthening assemblies that encode stored information.
► Serotonin is differentially involved in allocentric and egocentric working memory. ► Prefrontal serotonin depletion does not affect allocentric working memory. ► Prefrontal serotonin depletion ...impairs egocentric working memory.
Working memory is a cognitive ability chiefly organized by the prefrontal cortex. Working memory tests may be resolved based on allocentric or egocentric spatial strategies. Serotonergic neurotransmission is closely involved in working memory, but its role in spatial strategies for working memory performance is unknown. To address this issue, prefrontal serotonin depletion was induced to adult male rats, and three days after the behavioral expression of both allocentric and egocentric strategies were evaluated in the “Y” maze and in a crossed-arm maze, respectively. Serotonin depletion caused no effects on allocentric-related behavioral performance, but lesioned rats performed deficiently when the egocentric working memory was evaluated. These results suggest that serotonin may be more closely related with the organization of working memory that uses own movement-guided responses than with that involving the use of external visuospatial signals. Further neurochemical studies are needed to elucidate possible interactions between serotonergic activity and other neurotransmitter systems in the organization of working memory-related allocentric and egocentric strategies.
Introducción: Hasta donde se tiene conocimiento, en México esta indagación representa el primer trabajo multicéntrico que estudia el grado de desarrollo de la aptitud clínica en cuatro unidades de ...medicina familiar del Sector Salud. Por consiguiente, la interrogante de investigación es ¿cuál es el grado de desarrollo de la aptitud clínica en tres instituciones de salud? Este estudio proveerá conocimientos que permitirán emprender investigaciones en las cuales se ensayen estrategias educativas que propicien el desarrollo de esta aptitud.
Objetivo: Determinar el grado de desarrollo de la aptitud clínica en residentes de medicina familiar de cuatro sedes académicas.
Método: Diseño prospectivo, transversal, observacional y multicéntrico. Se estudió toda la matrícula del ciclo académico 2019-2020 con consentimiento informado. Se construyó un instrumento que evaluó la variable “aptitud clínica” mediante ocho indicadores y 182 ítems; la validez conceptual, de contenido y confiabilidad se valoró por cinco médicos familiares con experiencia docente y en investigación educativa.
Resultados: De las cuatro sedes, las calificaciones globales más altas en los indicadores fueron alcanzadas por los R1 de la Unidad de Medicina Familiar #20 del Instituto Mexicano del Seguro Social (UMF20 IMSS), R2 y R3 del Hospital General de Zona #1 (HGZMF1 IMSS). Los R1 de la UMF20 alcanzaron los más altos puntajes en 3/8 indicadores. Los R2 y R3 del HGZMF1 lograron las más altas puntuaciones en 2/8 indicadores. Se estimaron diferencias entre R1 (n = 46), entre R2 (n = 47) y entre R3 (n = 40) de las cuatro sedes por indicador y no se encontraron diferencias estadísticas significativas en ningún caso.
Conclusiones: El grado de desarrollo de la aptitud clínica se puede considerar de nivel medio en las cuatro sedes académicas. Esto, en parte, se puede explicar porque el instrumento exploró situaciones clínicas problematizadas, que exigieron al residente la reflexión crítica sobre su experiencia clínica antecedente.
