Broadcasting from adult-born dentate granule cells to the hippocampal circuitry

SILVIO GABRIEL TEMPRANA; ALEJANDRO F. SCHINDER; LUCAS A. MONGIAT

Huerta Grande, Cordoba

Congreso; Reunión Anual Sociedad Argentina de Investigación en Neurociencias; 2013

Sociedad Argentina de Investigacion en Neurociencias

p { margin-bottom: 0.25cm; direction: ltr; line-height: 120%; text-align: left; widows: 2; orphans: 2; } The dentate gyrus of adult mammals is a neurogenic region that continuously generates dentate granule cells (DGCs). New DGCs migrate, develop and integrate into the circuitry during a period of 6 to 8 weeks. Recently, we have proved that 4-week-old (immature) DGCs display low threshold for activation and high associativity to incoming inputs. Yet, the functional implication of these findings depends on the ability of immature DGCs to deliver information onto the target areas, and on the nature of the transmitted message. We are currently investigating whether immature DGCs can convey information to the hippocampal network and the nature of those signals. We combine retroviral transduction of neuronal progenitors with optogenetics to obtain cohorts of immature DGCs expressing channelrhodopsin-2 (ChR2). ChR2-DGCs can be activated by brief pulses of blue light delivered by a laser source. Acute hippocampal slices containing ChR2-DGCs were prepared and voltage clamp recordings were performed onto pyramidal neurons in CA3 and mature DGCs in the granule cell layer to monitor light-evoked postsynaptic currents (PSCs). In CA3 pyramidal neurons, light stimulation evoked excitatory and feedforward inhibitory PSCs, whereas mature DGCs only evidence light-induced feedback inhibition. Further experiments to establish the contribution of different cohorts of adult-born DGCs to information processing are currently underway.