title: Early gamma oscillations.
abstract: Gamma oscillations have long been considered to emerge late in development. However, recent studies have revealed that gamma oscillations are transiently expressed in the rat barrel cortex during the first postnatal week, a "critical" period of sensory-dependent barrel map formation. The mechanisms underlying the generation and physiological roles of early gamma oscillations (EGOs) in the development of thalamocortical circuits will be discussed in this review. In contrast to adult gamma oscillations, synchronized through gamma-rhythmic perisomatic inhibition, EGOs are primarily driven through feedforward gamma-rhythmic excitatory input from the thalamus. The recruitment of cortical interneurons to EGOs and the emergence of feedforward inhibition are observed by the end of the first postnatal week. EGOs facilitate the precise synchronization of topographically aligned thalamic and cortical neurons. The multiple replay of sensory input during EGOs supports long-term potentiation at thalamocortical synapses. We suggest that this early form of gamma oscillations, which is mechanistically different from adult gamma oscillations, guides barrel map formation during the critical developmental period.
authors.affiliation: INMED - INSERM U901, University Aix-Marseille II, Marseille, France; Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia. Electronic address: roustem.khazipov@inserm.fr.
authors.forename: R
authors.initials: R
authors.lastname: Khazipov
authors.forename: M
authors.initials: M
authors.lastname: Minlebaev
authors.forename: G
authors.initials: G
authors.lastname: Valeeva
mesh_terms: D000818:Animals; D004569:Electroencephalography; D025461:Feedback, Physiological / Q000502:physiology; D005260:Female; D006801:Humans; D009434:Neural Pathways / Q000254:growth & development / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D011247:Pregnancy; D013003:Somatosensory Cortex / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D013788:Thalamus / Q000502:physiology
keywords: CSD; EEG; EGO; EPSC; IPSC; L2/3; L4; LFP; MUA; N-methyl-d-aspartic acid; NMDA; P0; PSTH; PTX; STDP; VPM; VSD(I); cortex; current source density; dLGN; dorsal lateral geniculate nucleus; early gamma oscillation; electroencephalogram; electroencephalograms; excitatory postsynaptic current; gamma oscillations; inhibitory postsynaptic current; layer 2/3; layer 4; local field potential; multi-unit activity; neonate; peristimulus time histogram; picrotoxin; postnatal day 0; spike timing-dependent plasticity; thalamus; ventral posteromedial nucleus of the thalamus; voltage-sensitive dye (imaging)