Flexible spike timing of layer 5 neurons during dynamic beta oscillation shifts in rat prefrontal cortex.
Human brain oscillations occur in different frequency bands that have been linked to different behaviours and cognitive processes. Even within specific frequency bands such as the beta- (14-30 Hz) or gamma-band (30-100 Hz), oscillations fluctuate in frequency and amplitude. Such frequency fluctuations most probably reflect changing states of neuronal network activity, as brain oscillations arise from the correlated synchronized activity of large numbers of neurons. However, the neuronal mechanisms governing the dynamic nature of amplitude and frequency fluctuations within frequency bands remain elusive. Here we show that in acute slices of rat prefrontal cortex (PFC), carbachol-induced oscillations in the beta-band show frequency and amplitude fluctuations. Fast and slow non-harmonic frequencies are distributed differentially over superficial and deep cortical layers, with fast frequencies being present in layer 3, while layer 6 only showed slow oscillation frequencies. Layer 5 pyramidal cells and interneurons experience both fast and slow frequencies and they time their spiking with respect to the dominant frequency. Frequency and phase information is encoded and relayed in the layer 5 network through timed excitatory and inhibitory synaptic transmission. Our data indicate that frequency fluctuations in the beta-band reflect synchronized activity in different cortical subnetworks, that both influence spike timing of output layer 5 neurons. Thus, amplitude and frequency fluctuations within frequency bands may reflect activity in distinct cortical neuronal subnetworks that may process information in a parallel fashion.
van Aerde
Karlijn I
KI
VU University Amsterdam, Center for Neurogenomics & Cognitive Research, Department of Integrative Neurophysiology, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
Mann
Edward O
EO
Canto
Cathrin B
CB
Heistek
Tim S
TS
Linkenkaer-Hansen
Klaus
K
Mulder
Antonius B
AB
van der Roest
Marcel
M
Paulsen
Ole
O
Brussaard
Arjen B
AB
Mansvelder
Huibert D
HD
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000502:physiology*; D002478:Cells, Cultured; D009415:Nerve Net / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar