RESUMO
Los estudios electroencefalográficos en niños con Trastorno por déficit de atención con Hiperactividad (TDAH) reportan perfiles específicos en diferentes subtipos del trastorno. Este estudio investiga la presencia de alteraciones electroencefalográficas en un grupo de niños del subtipo hiperactivo/impulsivo y combinado. Se estudiaron 15 niños del subtipo hiperactivo/impulsivo y 15 del combinado del TDAH a los que se les realizó un electroencefalograma en vigilia. Los principales hallazgos al electroencefalograma fueron el incremento de la actividad lenta frontal y la presencia de descargas epileptiformes en ambos grupos. Se encontraron diferencias significativas entre los espectros de frecuencia de ambos grupos, por exceso en las bandas lentas y por defecto en las rápidas en el hiperactivo/impulsivo respecto al combinado. Estos resultados respaldan el modelo de un déficit de maduración del Sistema Nervioso Central como base del TDAH.
Electroencephalographic studies in children with Attention Deficit Hyperactivity Disorder (ADHD) report specific profiles in different subtypes. This study investigated the presence of Electroencephalogram abnormalities within a sample of children with the Hyperactive-Impulsive and combined subtypes of the disorder. Subjects consisted of 15 children of hyperactive-Impulsive and 15 children of combined subtypes. Electroencephalogram was recorded during an eyes closed resting condition. The principal findings were characterized by increased slow wave activity in frontal area and the visual analysis showed epileptiforms abnormalities in both groups. There was statistic difference in the spectrum of frequency in both subtypes characterized for more slow activity and less rapid activity in the hyperactive-Impulsive subtipe. These results support a model of ADHD resulting from a maturational lag in the Central Nervous System.
RESUMO
Growing evidence suggests that processes of synaptic plasticity, such as long-term potentiation (LTP) occurring in one synaptic population, can be modulated by consolidating afferents from other brain structures. We have previously shown that an early-LTP lasting less than 4 h (E-LTP) in the dentate gyrus can be prolonged by stimulating the basolateral amygdala, the septum or the locus coeruleus within a specific time window. Pharmacological experiments have suggested that noradregeneric (NE) and/or cholinergic systems might be involved in these effects. We have therefore investigated whether the direct intraventricular application of agonists for NE- or muscarinic receptors is able to modulate synaptic plasticity. E-LTP was induced at the dentate gyrus of freely moving rats using a mild tetanization protocol that induces only an E-LTP. NE or oxotremorine (OXO) were applied icv 10 min after the tetanus. Results show that low doses of NE (1.5 and 5 nM) effectively prolong LTP. A higher dose (50 nM) was not effective. None of the OXO doses employed (5, 25, and 50 nM) showed similar effects. These results stress the importance of transmitter-specific modulatory influences on the time course of synaptic plasticity, in particular NE whose application mimics the reinforcing effect of directly stimulating limbic structures on LTP.