We are only aware of our CNS brain and not directly, our PNS sensory body

[David777]

Will share some brain science today that few people understand.

On Google, I performed a search with an AI output per below for the sake of a better explanation than I could make myself. What most people do not understand about our nervous system mind, is that our conscious perception of body parts and senses is in the Central Nervous System, (abbreviation CNS) aka our brain, and not where whatever one seems to feel sensations are coming from.

For instance, when one touches say a toe that is perceived as touch in one's mind, it feels 3-dimensionally that the sensation is absolutely located where one is touched. But that is NOT being perceived in the toe or the spinal cord nerves that a toe connects to. Instead, from that spinal cord connection, another bundle of nerves in the spinal cord (Interneurons) routes up through the brain stem to a small element in the mid brain, called the Thalamus, where its secondary neurons then connect to the primary Somatosensory Cortex (abbreviation S1).

The somatosensory cortex contains a Homunculus structure that reflects the 3-dimensional shape of sensory nerves in the body with a size of each body element dependent on the amount of sense neurons and CNS processing of each body part. Accordingly, a finger has many more nerves than say a toe, so also has a larger S1 area than say a toe. When one feels touch to a toe, the perceived sensation is not actually at the toe even if that feels so, but is rather in the S1 homunculus structure where the electromagnetic field with brain waves are active.

That is why when dreaming, sensations of body parts can be as exactly like and seemingly as real as when awake and being touched so, because dreams access the same actual S1 elements where actual perceived awareness occurs. When asleep, the Peripheral Nervous System (abbr PNS) of our senses is greatly blocked from reaching S1 at the thalamus, so what we perceive in our mind instead comes from higher CNS brain areas as the cerebral cortex. In that sense, it is similar to a dual ported memory in electronics. Normally both ports are active on S1 but not during sleep. Our perceived senses are not fully just what is relayed from the thalamus but rather a processed combination of PNS signals and higher order CNS brain signals.

I search asked:
Can drug blockage of impulses from single spinal nerves be felt in brain?

Yes, the drug-induced blockage of a single spinal nerve can be felt in the brain, but not as pain. The sensation is typically a feeling of numbness, heaviness, or pins and needles in the specific body area that the blocked nerve serves. This is because the medication prevents nerve impulses from reaching the brain, which processes them as feelings.

How a spinal nerve block is felt in the brain:
When a drug is injected near a specific spinal nerve, it uses a local anesthetic to "shut down" the nerve's ability to transmit electrical signals. This process directly affects how the brain perceives the targeted area:

Preventing pain signals: By interrupting the pain signals at the spinal nerve level, the brain never receives the message of pain, providing localized pain relief.
Causing numbness: Since the nerve is also blocked from sending signals related to touch, temperature, and pressure, the brain interprets this lack of sensation as numbness or "pins and needles".
Influencing motor control: Depending on the nerve blocked, the patient may also experience temporary muscle weakness or a loss of muscle control in the corresponding body part.

The brain's response to the nerve block
While the nerve block is in effect, the brain's somatosensory cortex—the area that processes sensory information—is directly affected.

Deactivation of the somatosensory cortex: Studies have shown that when a nerve is blocked, the normal cortical activation in the affected brain hemisphere is suppressed. This is essentially the brain's way of "not feeling" the corresponding body part.
Enhanced cortical activity (paradoxical sensation): Interestingly, some studies have also found that in patients with chronic neuropathic pain, a nerve block can initially cause enhanced cortical activity. This is followed by a reduction in pain-related signals, offering a potential way to monitor the treatment's effectiveness.
"Phantom" sensations: As the block begins to wear off, the nerve's signaling ability slowly returns. This can cause the brain to interpret the returning signals as tingling or "pins and needles" before full sensation is restored.