The Five Pathways That Light Enters The Body

So J-P(on the Yahoo list DzogchenPractices) points to the Highest
Teaching (sudden) but doesn’t offer any easy way to get there. J-L
offers multlifold graduated steps to the View, but warns that the
highest stages are unattainable unless one finds a teacher and
preferably goes into seclusion.

Meanwhile, just smiling and blinking trigger for me an outpouring
of ecstatic bliss that is quite fulfilling, thank you very much!
And I suppose, over time, I will learn just to allow thoughts to
evaporate on their own without my needing temporary support (blinks)
to sneak between them to those light-filled realms. But meanwhile...
YUM! (smile)

J-L writes:

... inside the physical eyes opens the upper extremity of
the Kati channel connecting the pupils to the center
of the heart. It is within this channel that the glow
of Awareness (the visions of Clear-Light) arises. To
make things easy, this channel is designated as the
channel of light (?od kyi rtsa).

Question:
whenever I meditate (gaze) on the sun, my heartbeat increases
considerably and an intense bliss arises. Is this because of
the Kati channel's connection to the heart center?

J-L continues:

Now, some texts say that there are four or five channels of light...

Comment:
By coincidence, the text below on color therapy and holistic healing
also discusses five pathways by which light enters the body:
“The Neurophysiology of Light- The Five Pathways” by Dietrich Klinghardt (1995)
in which the author describes as follows (briefly excerpted from the
only two chapters translated from the German):

The Neurophysiology of Light: the Five Pathways
1. The optic nerve travels from the retina, past the
pituitary gland via the temporal lobe to the occipital
lobe of the brain. This part of the visual system
is dedicated to informing the conscious part of our
brain of our surroundings.
2. An additional nerve bundle is leading directly from
the retina to the hypothalamus (retino-hypothalamic tract).
This explains the above mentioned strictly physiological
effect of color on the ANS (Autonomic Nervous System):
3.A side-branch of this nerve tract reaches the amygdala
directly, bypassing the hypothalamus. The two corpora
amygdaloidea are truly the color sensitive area of
the limbic system and highly responsive to the color the
eyes are exposed to. A study demonstrated that each mono-
chromatic color frequency excites specific neurons. If
adjacent, but dissimilar color-wavelengths are used, the
same neuron stays unexcited. Each frequency in the
color spectrum therefore has its own specific neurological
and psychological effect. ... The profound effect of light
stimulation to the retina on the body’s metabolism has
long been established through the work of the brilliant
German ophthalmologist Fritz Hollwich, M.D.,Ph.D.
4. A fourth nerve connection from the retina follows the
lower optic tract, which is not used for vision, and
reaches the transpeduncular nucleus in the midbrain. This
nucleus is also light and color sensitive. From here the
signal travels via the superior cervical ganglion back via
the brainstem to the pineal gland. This pathway is –
amongst other less understood functions – responsible for
the circadian day-night rhythm and the melatonin production
in the pineal gland when it gets dark. This pathway has
been given much attention lately in research concerning
the treatment of seasonal affective disorder. Via secondary
interneurons all of these pathways are connected with each
other and virtually each area of the brain.
5. A fifth, and maybe most exciting way in which color
finds it’s way inside the body, i.e. the subconscious mind,
the immune system, the limbic system, the nervous system,
etc. - has only recently been discovered. There are more
and more scientific hints that light can charge particles
that travel in the lymph and blood as well as axonally inside
the nerves. Researchers at the University of Vienna, Austria,
found that albumin is one of the proteins able to be charged
by colored light – and able to deliver this charge to tissues
far away from the site of exposure. Through the outer layer
of the skin light also affects pigments, fluorescent particles
in the body fluids and inside the cells which travel in the
blood and lymph. After being energized - in a color-wave-
length and frequency-specific way - they are transported to
their target sites where the light-energy is discharged. These
light-discharges have an organizing and activating effect on
cellular organelles and the cell metabolism in the target
tissue (such as the brain or inner organs). ... The German
scientist Fritz Albert Popp PhD confirmed the prior research
of Russian scientists, and published many of his own papers,
on the fact that all cells in an organism use subtle light
emissions to communicate with each other constantly. Cells
gossip, inform, celebrate and grieve. Only cancer cells
behave differently: they do not emit light. Recent research
in stem cell therapy brought to light another astounding
phenomenon: when cells are ill or in distress, they also give
off “microscopic” sound signals. If the sound of a group
of dying cells is artificially amplified, it sounds like a
group of weeping and grieving women. Injected stem cells
(from embryonic umbilical chords) follow this signal and settle
in the area to lend their support.
Stem cells are compassionate. Cells care for each other.