I know this is asking a lot, but would anybody like to weigh in with some explanation/evidence for the descriptions of those four parts of the brain?
The thalamus does function as a 'gatekeeper', although that's a bad term, the level to which the thalamus processes sensory input isn't fully understood / agreed upon. It's more like a transit hub connecting all the various parts of the brain and sensory tracts. It receives a lot of sensory fibers from the eyes, nose, ears, tongue.
For the parietal lobe, 'orienting you in time and space' just means that the parietal lobe creates a 3D grid system that helps in coordinating muscle movements. This system is supported by sensory input (auditory and visual). The parietal lobe will receive input from other lobes as well as the thalamus.
The frontal lobe is fairly well described, it basically handles higher level thinking, moral decisions, etc. It receives input from other lobes, the thalamus, and the brain stem.
An important take away is that these are really non-specific anatomical regions, the thalamus has ~30 distinct regions all handling different things. The frontal lobe has numerous gyri (regions) with different functions ranging from executive to motor skills.
What he's saying is pretty bs too. The logical conclusion is not that meditation specifically reduces brain activity, it's more that any lack of sensory stimulation will cause brain activity to slow down because less neurons are firing, this can be achieved with other techniques as well, simply staring at a wall will do the same thing.
I can post sources if you'd like but this information (about the compartments of the brain) is very well accepted by those in the medical sciences.
seems to debunk
"The logical conclusion is not that meditation specifically reduces brain activity, it's more that any lack of sensory stimulation will cause brain activity to slow down because less neurons are firing"
Perhaps the authour isn't really that familiar with the material?
Btw beta waves can also be recorded using a single electrode: normally these get used to record spikes from a single neuron, but they also pick up the lower frequency bands of all surrounding neurons. The nice thing is this provides a more local view (iirc everything that is closer than a couple of mm around the electrode), whereas an EEG gets you 'everything' so it's more an indication about general brain state without giving information about which part is active.
This is gross misunderstanding of what happens when people meditate. Of course, the whole word meditation is very generic term. Saying that you meditate is like saying that you do sports.
Most traditional meditation techniques the meditation is exercise in concentration and awareness. You are active and constantly doing something with your mind even if you are relaxed.
So the aim is to stop thinking random thoughts not for the sake of "no brain activity" but for a SPECIAL form of brain activity, which some traditions call "revelations"