Traveling Theta Waves in the Human Hippocampus PMC

Think about your brain waves as a spectrum that ranges from very fast to very slow. This spectrum would not be complete without all five types of brain waves. In this article, we’ll take a closer look at theta brain waves, their function, and how they differ from other types of brain waves. The EEG measures brainwaves of different frequencies within the brain. Electrodes are placed on specific sites on the scalp to detect and record the electrical impulses within the brain. A frequency is the number of times a wave repeats itself within a second. It can be compared to the frequencies that you tune into on your radio.

Slow brainwaves, with a frequency of 4–6 Hz, which are common in sleep, relaxation, and deep meditation. Winson J. Loss of hippocampal theta rhythms in spatial memory deficit in the rat.

EEG artefacts

However, it was unclear if alpha waves control attention or are just a byproduct of some other process that governs attention, Desimone says. When you initially wake from sleep, your brain first drifts through theta waves and then through alpha waves. These are the frequencies your brain is operating at when you are in a deeply relaxed state, like when you’ve just woke up or during meditation, Brain Waves and it’s here where the bridge between you and your subconscious mind is most accessible. Some research suggests that patterns of alpha brain wave activity are different in people who have insomnia compared to people who do not. One study found that people with insomnia experience increased alpha wave activity and greater variation in alpha frequency before falling asleep.

Upper panel shows spiking of individual neurons , and the lower panel the local field potential reflecting their summed activity. Figure illustrates how synchronized patterns of action potentials may result in macroscopic oscillations that can be measured outside the scalp.

What is the function of the various brainwaves?

O’Keefe J, Recce ML. Phase relationship between hippocampal place units and the EEG theta rhythm. Miller KJ, Leuthardt EC, Schalk G, Rao RP, Anderson NR, Moran DW, Miller JW, Ojemann JG. Spectral changes in cortical surface potentials during motor movement. Jacobs J, Kahana MJ. Neural representations of individual stimuli in humans revealed by gamma-band ECoG activity. https://wave-accounting.net/ Electrode locations were identified by inspecting post-implant CT scans, which were then aligned with MRI scans from before electrode implantation. We computed each electrode location in 3D space using Talairach coordinates and distinguished electrodes that were located outside of the hippocampus (Talairach and Tournoux, 1988; Insausti and Amaral, 2004).

There were also no baseline, ‘normal’ brain scans of this patient to compare the brain activity to. However, by definition we can’t have access to such data in healthy patients whose deaths are impossible to anticipate. Therefore, obtaining recordings of the near-death phase could only come from an already ill patient.

How Sleep Works: Understanding the Science of Sleep

Alpha waves were among the first waves documented by Berger, along with beta waves, and he displayed an interest in “alpha blockage”, the process by which alpha waves decrease and beta waves increase upon a subject opening their eyes. This distinction earned the alpha wave the alternate title of “Berger’s Wave”. A study has shown that the appearance of an alpha rhythm with open eyes can be a predictor of visual information processing in working memory. It was shown that the moment of appearance of alpha activity depends on the type of stimulus in memory and the number of visual characteristics (color, shape, etc.) that it needs to keep in memory. The authors suggest that the appearance of the alpha rhythm with open eyes may indicate a temporary shutdown of visual information processing in the primary visual cortex at the moments when the subject analyzes the image in visual memory. At these moments, information is processed in the association areas of the visual cortex . It has long been believed that alpha waves indicate a wakeful period during sleep.