The descriptions are generally accurate, although very broad. The reticular formation is part of the brain stem, responsible for supporting breathing, cardiac function, and other somatic functions. The most relevant function is it's control of alertness and circadian rhythms.
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.
"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"
Also, surely the presence of beta waves (12-30Hz) needs to be detected by an electroencephalogram (EEG), not fMRI? I thought fMRI has a much lower temporal resolution (~1Hz).
I think the image was mischaracterised. The fMRI will show changes in activity and if the image is actually from an fMRI post meditation then the authour may have just extrapolated from 'reduction in beta waves' to 'less activity on this colour gradient image'.
Perhaps the authour isn't really that familiar with the material?
I can't find a good article atm, but afaik there's an established correlation between fMRI activity (indeed about 0.5/1 slices per second depending on settings) and beta waves.
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.
>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.
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.
As far as i understand, traditionally, meditation isn't about simply shutting down your mind as a whole. it is about:
1) Concentration (shutting down NOISE)
2) Shutting down thoughts from one source (or chaotic sources) to open up your mind to a particular source (some traditions mean opening up to ur inner self while others mean opening up to a higher source)
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"
