title: Bursting Neurons in the Hippocampal Formation Encode Features of LFP Rhythms.
abstract: Burst spike patterns are common in regions of the hippocampal formation such as the subiculum and medial entorhinal cortex (MEC). Neurons in these areas are immersed in extracellular electrical potential fluctuations often recorded as the local field potential (LFP). LFP rhythms within different frequency bands are linked to different behavioral states. For example, delta rhythms are often associated with slow-wave sleep, inactivity and anesthesia; whereas theta rhythms are prominent during awake exploratory behavior and REM sleep. Recent evidence suggests that bursting neurons in the hippocampal formation can encode LFP features. We explored this hypothesis using a two-compartment model of a bursting pyramidal neuron driven by time-varying input signals containing spectral peaks at either delta or theta rhythms. The model predicted a neural code in which bursts represented the instantaneous value, phase, slope and amplitude of the driving signal both in their timing and size (spike number). To verify whether this code is employedin vivo, we examined electrophysiological recordings from the subiculum of anesthetized rats and the MEC of a behaving rat containing prevalent delta or theta rhythms, respectively. In both areas, we found bursting cells that encoded information about the instantaneous voltage, phase, slope and/or amplitude of the dominant LFP rhythm with essentially the same neural code as the simulated neurons. A fraction of the cells encoded part of the information in burst size, in agreement with model predictions. These results providein-vivoevidence that the output of bursting neurons in the mammalian brain is tuned to features of the LFP.
authors.affiliation: Faculty of Biology, Medicine and Health, The University of Manchester Manchester, UK.
authors.forename: Maria
authors.initials: M
authors.lastname: Constantinou
authors.affiliation: Centro Atómico Bariloche and Instituto Balseiro San Carlos de Bariloche, Argentina.
authors.forename: Soledad
authors.initials: S
authors.lastname: Gonzalo Cogno
authors.affiliation: Faculty of Biology, Medicine and Health, The University of Manchester Manchester, UK.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Elijah
authors.affiliation: Leloir Institute, IIBBA-CONICET Buenos Aires, Argentina.
authors.forename: Emilio
authors.initials: E
authors.lastname: Kropff
authors.affiliation: Faculty of Biology, Medicine and Health, The University of Manchester Manchester, UK.
authors.forename: John
authors.initials: J
authors.lastname: Gigg
authors.affiliation: Centro Atómico Bariloche and Instituto Balseiro San Carlos de Bariloche, Argentina.
authors.forename: Inés
authors.initials: I
authors.lastname: Samengo
authors.affiliation: Faculty of Biology, Medicine and Health, The University of Manchester Manchester, UK.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Montemurro
keywords: bursting; entorhinal cortex; information theory; local field potential; neural coding; subiculum