Affective, Cognitive, and Motivational Processes of Maternal Care

Multiparity decreases the effect of distractor stimuli on a working memory task: An EEG study

Parity modulates the way in which women respond to infant's affective cues. It is known that the cognitive processing of mothers is affected by a baby crying; however, little information is available regarding the effect of reproductive and caregiving experience on efficiency in managing babies' emotional stimuli while other tasks are being attended. This study characterized the affective score, cognitive performance, and electroencephalographic correlation (rEEG) between prefrontal and parietal cortices in first- (FM) and second-time mothers (SM) while solving a working memory task (vsWM) and simultaneously listening to either an emotional or neutral distractor stimulus. During the vsWM-baby crying condition, both groups reported higher arousal. However, SM reported a lower valence and FM lower dominance. In the vsWM-baby crying condition did SM need less time to solve the cognitive task and present a decreased rEEG between prefrontal areas, and between left prefrontal and parietal areas, though an increased rEEG between parietal areas was observed while listening to both distractor stimuli during performance of the vsWM task. These degrees of cortical synchronization could constitute a cerebral mechanism required to achieve better information maintenance and enhance suppression of distractor effects, which allow the SM women to solve the vsWM task more efficiently.

Cocaína durante la gestación y conducta materna postparto en ratones

El abuso materno de cocaína durante la gestación se relaciona con negligencia, maltrato y perturbación del vínculo madre- hijo, lo que incide directamente en el desarrollo de los infantes; por esto, las diversas problemáticas neuroconductuales de los hijos de padres drogodependientes podrían atribuirse a la inadecuada conducta materna o a la exposición prenatal a la droga. El objetivo de esta investigación fue analizar los efectos de la administración crónica de cocaína durante la gestación en la conducta materna postparto de ratones. Para esto se asignaron aleatoriamente 21 ratones CD1 hembras gestantes para la administración de solución salina y cocaína (25 mg/kg/día y 50 mg/kg/día), desde el octavo hasta el día veintiuno de gestación. Después del parto, durante 20 días (15 minutos diarios), se registró individualmente la frecuencia de presentación de 16 índices de conducta materna mediante un etograma. Se encontró que la cocaína afectó levemente la frecuencia de la conducta materna, aunque posiblemente afecte otros parámetros como la latencia, duración y secuencia de esta conducta.  

Motherhood and infant contact regulate neuroplasticity in the serotonergic midbrain dorsal raphe

The adult brain shows remarkable neuroplasticity in response to hormones and the socioemotional modifications that they influence. In females with reproductive and maternal experience, this neuroplasticity includes the birth and death of cells in several forebrain regions involved in maternal caregiving and postpartum affective state. Such plasticity in midbrain sites critical for these behavioral and emotional processes has never been examined, though. By visualizing bromodeoxyuridine (BrdU) to label mitotic cells, NeuroD for neuronal precursors, and TUNEL to identify dying cells, we found that the midbrain dorsal raphe nucleus (DR, the source of most ascending serotoninergic projections) exhibited significant neuroplasticity in response to motherhood. Specifically, BrdU analyses revealed that DR newborn cell survival (but not proliferation) was regulated by reproductive state, such that cells born early postpartum were less likely to survive 12 days to reach the late postpartum period compared to cells born during late pregnancy that survived 12 days to reach the early postpartum period. Many of the surviving cells in the DR were NeuN immunoreactive, suggesting a neuronal phenotype. Consistent with these findings, late postpartum rats had fewer NeuroD-immunoreactive DR cells than early postpartum rats. Maternal experience contributed to the late postpartum reduction in DR newborn cell survival because removing the litter at parturition increased cell survival as well as reduced cell death. Unlike cytogenesis in the maternal hippocampus, which is reduced by circulating glucocorticoids, DR newborn cell survival was unaffected by postpartum adrenalectomy. These effects of reproductive state and motherhood on DR plasticity were associated with concurrent changes in DR levels of serotonin's precursor, 5-HTP, and its metabolite, 5-HIAA. Our results demonstrate for the first time that cytogenesis occurs in the midbrain DR of any adult mammal, that DR plasticity is influenced by female reproductive state and maternal experience, and that this plasticity is accompanied by changes in DR serotonergic function. Because serotonin is critical for postpartum caregiving behaviors and maternal affective state, plasticity in the DR may contribute to the neurochemical changes necessary for successful motherhood.