simplified structure of NS - Impulsing shows how to trace impulse activity in the nervous system in the form of "impulse trails" ... Focus is on the work they do as four linked areas of the system are energized. These are the areas neuroscientists associate with four kinds of conscious work.

let’s outline the physical character of this model … with a simplified structure of the NS …

so, we’ll begin by looking at this system … as being made up of groups of specialized cells … called neurons.

neurons often have long connecting branches, which join … neuron groups together …

so, this system is a circuitry of connected neuron groups … in the body …

this circuitry begins with the sensory neuron groups that are embedded in the body’s tissues & with their branches, they reach inward to form the spinal cord- & as they reach higher in the body, groups are packed tog – to form the brain

then, from the brain, branches connect through many of the same routes … back to the body’s tissue …

such as to the muscle … where they are in contact with the adjacent sensory groups … such as the tension receptors in the muscle … which, in effect … completes … or closes the circuitry

so, with this backdrop in mind, we’ll focus on four areas of the system that are linked together to makeup an inner circuitry … the conscious pathways …

the first link of this inner circuitry starts with the sensory groups … groups of receptors in the eyes, ears, skin & muscle

that all reach inward … to the thalamus … which is a set of groups packed together … near the center of the brain

the 2^nd link starts at the thalamus … with connections fanning out, from separate groups of the thalamus … to reach …

separate corresponding areas or patches of the cortex … which is like a thin patchwork-quilt … that’s made up … of neurons in layers … covering the surface of the brain …

the 3^rd link of this inner circuitry … is formed … as connections from the cortex … reach back … to the thalamus …

so connections to the thalamus … enter from two directions … from the sensory groups … and from the cortex

finally the 4^th link … is actually a sub-circuit … it also begins at the cortex and ends at the thalamus … but in this case … connections from the cortex, reach first to the muscle … and then, from the muscle, connect back to the thalamus

and the thalamus, by the way, is a part of the system that neuroscientists often refer to … when they discuss consciousness