Gamma Oscillations Are Generated Locally in an Attention-Related Midbrain Network

Gamma-band (25–140 Hz) oscillations are a hallmark of sensory processing in the forebrain. The optic tectum (OT), a midbrain structure implicated in sensorimotor processing and attention, also exhibits gamma oscillations. However, the origin and mechanisms of these oscillations remain unknown. We di...

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Bibliographic Details
Published in:Neuron (Cambridge, Mass.) Mass.), 2012-02, Vol.73 (3), p.567-580
Main Authors: Goddard, C. Alex, Sridharan, Devarajan, Huguenard, John R., Knudsen, Eric I.
Format: Article
Language:English
Subjects:
Animals
Animals, Newborn
Atropine - pharmacology
Attention
Attention - physiology
Biophysics
Brain Mapping
Chickens
Electric Stimulation
Excitatory Amino Acid Antagonists - pharmacology
GABA Antagonists - pharmacology
GABA Modulators - pharmacology
In Vitro Techniques
Mesencephalon - physiology
Muscarinic Antagonists - pharmacology
Pentobarbital - pharmacology
Periodicity
Photic Stimulation
Picrotoxin - pharmacology
Receptors, Cholinergic - metabolism
Receptors, GABA - metabolism
Receptors, N-Methyl-D-Aspartate - metabolism
Studies
Superior Colliculi - physiology
Synaptic Potentials - drug effects
Valine - analogs & derivatives
Valine - pharmacology
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Summary:Gamma-band (25–140 Hz) oscillations are a hallmark of sensory processing in the forebrain. The optic tectum (OT), a midbrain structure implicated in sensorimotor processing and attention, also exhibits gamma oscillations. However, the origin and mechanisms of these oscillations remain unknown. We discovered that in acute slices of the avian OT, persistent (>100 ms) epochs of large amplitude gamma oscillations can be evoked that closely resemble those recorded in vivo. We found that cholinergic, glutamatergic, and GABAergic mechanisms differentially regulate the structure of the oscillations at various timescales. These persistent oscillations originate in the multisensory layers of the OT and are broadcast to visual layers via the cholinergic nucleus Ipc, providing a potential mechanism for enhancing the processing of visual information within the OT. The finding that the midbrain contains an intrinsic gamma-generating circuit suggests that the OT could use its own oscillatory code to route signals to forebrain networks. ► Evoked gamma oscillations in the OT in vitro resemble those observed in vivo ► GABA-Rs, Ach-Rs, and NMDA-Rs modulate oscillation structure at various timescales ► Persistent gamma oscillations are generated by a circuit in the deep, multisensory OT ► Oscillations are broadcast to the superficial, visual OT via a cholinergic nucleus Forebrain gamma oscillations are implicated in sensory processing and attention. Goddard et al. find that gamma oscillations, controlled by similar mechanisms, can be evoked in the avian optic tectum in vitro. This midbrain oscillatory code could be used to route signals to forebrain networks.
ISSN:0896-6273
1097-4199
DOI:10.1016/j.neuron.2011.11.028