[Buddha-l] Shamatha Research, was book

[S.A. Feite]

Here's what may be happening in shamatha practice, from a researcher  
in AZ:

" In recent years gamma synchrony has indeed been shown to derive not  
from
axonal spikes and axonal-dendritic synapses, but from post-synaptic
activities of dendrites. Specifically, gamma synchrony/40 Hz is  
driven by
networks of cortical inter-neurons connected by dendro-dendritic
“electrotonic” gap junctions, windows between adjacent cells. Groups of
neurons connected by gap junctions share a common membrane and fire
synchronously, behaving (as Eric Kandel says) "like one giant  
neuron." Gap
junctions have long been recognized as prevalent and important in
embryological brain development, but gradually diminish in number (and
presumably importance) as the brain matures. Five years ago gap  
junctions
were seen as irrelevant to cognition and consciousness. However more
recently, relatively sparse gap junction networks in adult brains  
have been
appreciated and shown to mediate gamma synchrony/40 Hz.1-11 Such  
networks
are transient, coming and going like the wind (and Hebbian  
assemblies), as
gap junctions form, open, close and reform elsewhere (regulated by
intraneuronal activities). Therefore neurons (and glia) fused  
together by
gap junctions form continually varying syncytia, or Hebbian "hyper- 
neurons"
whose common membranes depolarize coherently and may span wide  
regions of
cortex. (The internal cytoplasm of hyper-neurons is also continuous,
prompting suggestions they may host brain-wide quantum states.) By  
virtue of
their relation to gamma synchrony, gap junction hyper-neurons may be the
long-sought neural correlate of consciousness (NCC).

Which brings us to the study by Antoine Lutz and colleagues in the
Proceedings of the National Academy of Sciences USA, a prestigious and
austere (one might even say stodgy) journal of extremely high repute.  
The
authors compared EEG in two subject groups before and during  
meditation--not
of an object or activity, but of a pure feeling of unreferenced  
compassion.
Dare I say this pure feeling might be deemed a quale?

One subject group was composed of young students trained for a week in
meditative technique; the second group consisted of Tibetan Buddhist
practitioners with 15 to 40 years of meditation training and  
practice. The
EEG methodology was rigorous, and the results were clear. Compared to  
novice
meditators, the highly trained Tibetan Buddhist meditators had markedly
higher amplitude, long-range global gamma synchrony in bilateral  
frontal and
parietal/temporal regions. An increase in gamma synchrony was also  
observed
in baseline measurement (before meditation) which became enhanced and  
more
global during meditation in the trained Tibetan meditators.

For technical reasons (possible muscle artifact and 60 Hz AC  
interference)
the absolute frequency spectrum was not determined, though the  
experimenters
hinted of a significant rise in synchrony and amplitude in the 80 to  
120 Hz
range during the Tibetans' meditation. The coherence and power in the  
range
of 25 to 42 Hz was significantly increased statistically. (Coherence is
usually defined as synchrony with a very brief lag, on the order of a  
few
milliseconds). Amplitude of the synchronized gamma activity was  
greater than
any previously reported nonpathological (i.e. non seizure-based) gamma
synchrony.

So, what does this tell us about consciousness? Well first, there is an
increase in gamma synchrony amplitude and coherence during what I  
think is
fair to call an enhanced state of consciousness' pure intense experience
unfettered by cognitive contents. This supports the notion of gamma
synchrony as an electrophysiological correlate of consciousness.

Second, the trained Tibetan meditators had baseline increases in gamma
synchrony and amplitude, suggesting long-term changes in their brains  
from
years of meditation. One might say they are more highly conscious in a
baseline state, achieving even greater intensity of consciousness during
meditation.

In a book titled The Quantum and the Lotus by Mathieu Ricard and  
Trinh Xuan
Thuan (Crown Publishers, 2001), Ricard (a molecular biologist turned
Buddhist meditator and co-author of the Lutz study) describes the  
Buddhist
concept of three levels of consciousness, including the most important
"fundamental luminosity of the mind". This is a "state of pure awareness
that transcends the perception of a subject/object duality and breaks  
free
from the constraints and traps of discursive thought." Moreover this  
form of
consciousness, according to Mathieu Ricard, can exist independently  
of the
brain, and in fact pervades the universe. Presumably, the meditative  
state
marked by enhanced gamma synchrony represents an immersion of the  
subjects
in this fundamental luminosity. (Such a connection may possibly be  
explained
through the quantum approach to consciousness. For example the
Penrose-Hameroff model suggests a connection between brain processes  
and a
fundamental Platonic realm embedded in the space-time continuum.12,13)

Back to the brain. The enhanced gamma synchrony during the meditative  
state
(as the authors tell us) is most likely due to a) an increase in the  
size of
coherently responding neural assemblies, and/or b) increased  
precision in
the coherence of responding neural assemblies.

Before addressing these possibilities, consider the origin of coherence.
Even assuming that cortical neuronal assemblies interconnected by gap
junctions ("hyper-neurons") are the neural correlate of gamma synchrony,
there are two possibilities for the coherence. One is that ascending or
re-entrant thalamo-cortical inputs drive the cortical neuronal  
assemblies,
like a piano player might rhythmically strike keys on a piano. The  
other is
that the cortical neuronal assembly (hyper-neuron) itself is the  
source of
coherence, due either to some internal reverberative feedback or common
underlying mechanism in the extended membrane and/or cytoplasm/ 
cytoskeleton.
There are arguments against the thalamo-cortical drive mechanism for
coherence based on delays in chemical neurotransmission and the slightly
varying lengths of thalamo-cortical axons required to reach appropriate
regions of cortex. In addition, thalamo-cortical drive would mean  
that the
thalamus (rather than cortex) was responsible for choosing areas of  
cortex
for consciousness (though proponents of this view point to cortical- 
thalamic
feedback). These are open questions, though the fact that meditators  
whose
consciousness is devoid of sensory inputs from the external world  
exhibit
more highly coherent cortical excitations suggests that thalamic inputs
reduce, rather than promote, gamma synchrony. Thus both enhanced a)  
size and
b) coherence precision of cortical assemblies seem likely.

(...)

One could say (I would not) that the gamma synchrony/coherent 40 Hz
corresponding with contentless meditation implied a blank slate, perhaps
like a radio station carrier wave, that the coherent amplitude  
increase was
due to lack of interference stemming from lack of cognitive  
processing. But
the trained meditators were conscious"highly conscious" of the  
feeling of
pure compassion. So my impression, as suggested above, is that their
enhanced gamma synchrony reflected a release from external (e.g.  
thalamic)
distractions, allowing pure qualia to fill consciousness. Why gamma
synchrony (or any brain activity) should be conscious is, of course the
"hard problem". As those familiar with my views might suppose, my  
guess is
that conscious experience derives from quantum mechanisms in  
cytoskeletal
structures within coherently excited components of hyper-neurons.  
These in
turn facilitate a more direct absorption in what Buddhists call  
fundamental
luminosity. My guess is also that intensity of experience corresponds  
not
only with coherence, but also frequency, that the 80 to 120 Hz  
coherence is
present in the trained meditators and represents the highest form of
consciousness. "

 From http://sci-con.org/2005/05/breakthrough-study-on-eeg-of- 
meditation/