Tesis Doctorado
A biólogical context for theta-frequency neuronal resonance: a comparative study between cortical amygdala and hippocampal neurons
Autor
Sanhueza-Tohá, Magdalena
Universidad de Chile
Institución
Resumen
Neurons from different memory-related mammalian brain regwns display intrinsicmaximal subthreshold voltage responses to oscillatory stimulation at theta frequencies(4-12Hz; theta resonance). This may contribute to tune and stabilize network oscillatory activity. However, the drop in input resistance (Rin) produced by synaptic bombardment in active networks predicts a loss of resonance impact on neuronal processing. To investigate wbether resonance drives rhythmic spiking in active networks we performed a comparative study of two resonant neuron populations with different Rin, pyramidal neuron from CAl hippocampus (CAlP, - 60 MΩ) and neurons from tbe anteriornucleous of the cortical amygdala (ACoN, - 160 MΩ) using rat brain slices, whole-cellrecordings and dynamic clamp. A hyperpolarization-activated cationic current (I in) contributed to subthreshold resonance in botb neuronal groups. Favored by the high R in, ftr also filtered perithreshold voltage oscillations in ACoN, tbus allowing the translation of resonance to spiking regimes even under recreated synaptic bombardment. In tum, CAlP neurons displayed a tunable mecbanism for resonance translation to spiking based on relative levels of a muscarine-sensitive potassium current (IM) and a persistent sodium current (INaP). Notably, we confirmed the prediction of RLC-filter theory that cbanges in Rin, due to synaptic bombardment modulate resonance frequency and strength.CAlP bave five-fold more INaP tban ACoN, increasing perithreshold impedance and tbuscompensating tbe low Rin. Therefore, neurons witb opposed Rin values implementdifferent strategies to effectively translate their frequency preference to spiking regimes. We present a novel aspect of neuronal resonance, consisting of a dynamic tunablemechanism for intrinsic frequency preference that depends on the level of networkactivity.