Gamma Waves and Consciousness - III

Generation and Oscillatory Properties of Gamma Waves in the brain

6/29/20232 min read

The generation and oscillatory properties of gamma waves involve the coordinated activity of large populations of neurons within the brain. These properties contribute to the unique characteristics and functional significance of gamma oscillations. Here are the key aspects of the generation and oscillatory properties of gamma waves:

1.Neural Synchronization: Gamma waves arise from the synchronization of neuronal firing patterns across distributed neural networks. When large groups of neurons fire together in a synchronized manner, they generate rhythmic electrical activity in the gamma frequency range. This synchronization is thought to be facilitated by inhibitory interneurons that act as pacemakers, setting the rhythm of the gamma oscillations.

2. Pyramidal-Inter Neuronal Network: One proposed mechanism for gamma wave generation is the interaction between pyramidal neurons, which are the principal excitatory neurons in the brain, and inhibitory interneurons. Pyramidal neurons receive sensory inputs and generate excitatory signals, while inhibitory interneurons, particularly those expressing the neurotransmitter gamma-aminobutyric acid (GABA), provide inhibitory control. The interplay between these cell types creates a balanced excitation-inhibition dynamic that promotes gamma oscillations.

3. Feedback and Feedforward Loops: Gamma oscillations often involve the interaction between different brain regions through feedback and feedforward loops. Feedback loops occur when neural activity travels in a recurrent manner between interconnected brain regions, while feedforward loops involve the sequential activation of brain regions. These loops allow for the propagation and amplification of gamma oscillations across the brain, facilitating the coordination of information processing and integration.

4. Cross-Frequency Coupling: Gamma waves can exhibit cross-frequency coupling with other slower brain wave frequencies, such as theta (4-7 Hz) or alpha (8-12 Hz) waves. Cross-frequency coupling refers to the phenomenon where the amplitude or phase of a slower oscillation modulates the power or timing of the gamma oscillations. This coupling allows for the temporal organization and integration of different cognitive processes, enabling the coordination of information flow across brain networks.

5. Broadband Gamma Activity: In addition to the specific gamma frequency range, there is evidence of broadband gamma activity that extends beyond the traditional gamma band. Broadband gamma activity refers to a broader range of frequencies, typically from low gamma to high gamma, and is observed in certain brain states and cognitive tasks. This extended range of gamma activity may reflect the simultaneous engagement of multiple neuronal assemblies and networks.

6. Short Transients and Bursting Activity: Gamma oscillations are often characterized by short transients or bursting activity, where brief episodes of high-frequency oscillations occur in a phasic manner. These bursts of gamma activity are associated with the processing of sensory stimuli, attentional focus, and cognitive operations. The phasic nature of gamma bursts enables the rapid integration and communication of information across different brain regions.

Part 04 will be dealing with Neural Networks and Gamma Synchronization.