If for some reasons a brain would be deprived off all inputs, it (he/she) would still have memories to process and all thoughts would be based on past experiences. But in case a person was born without any inputs to hint there is "anything out there", would the mind/brain somehow go on? Would it be aware of time (at least biological rhythms, since it would probably still need sleep), of causality, of self? Now I'm not sure if this is a hypothetical question, or if some data on the subject exists from a real-world observation/research or at least a deduction from our knowledge of how the brain works?
To date, it is still impossible to sustain a brain without sensory input. A brain without ANY sensory input will ultimately die by series of maladies, even before it forms completely.
I speak things by nutshell.
You can sever someone's (or anything's) neuron circuit to prove my answers are right or wrong.
I also have a bad sense of humor, pardon me.
Reference: I refer my talks solemnly to:
- Sherwood's Human Physiology. On homeostasis
- Purves' Neuroscience. This is the main reference.
- Gilbert's Developmental Biology. It says so.
To address your question, we need to specify the main topics: Homeostasis, Integration, and Development.
Homeostasis is a dynamic state of balance between input and output, or between anything else. We learn thus mostly in Physiology.
Integration is a topic central to neuroscience, too! Those inputs coming through the sensory system is processed, combined, and translated into actions by the output system.
Development is a progressive change from a zygote to an adult. This topic runs in the fine-tuned balance of homeostasis by integration.
deprived off all inputs
The context of input a very (very) wide subject in Neuroscience.
Crash course: inputs can be propioception, mechanical, chemical, et. al..
You might be referring to the Classical 5 (or more) Senses, but actually the human body has almost 20 types of sensory inputs.
One example of them is chemoreception. The is one part of your brain that "senses" the chemical condition of the ECF (the fluid bathing your cell). The chemicals "tested" could be carbon dioxide, hydrogen ions (acidity), or even adenine.
If this input goes "puff" away, your brain will go cuckoos in seconds.
person was born without any inputs to hint there is "anything out there"
Since all input system has been severed, integration will be impossible, hence the person will not only unable to perceive the surroundings, but also the inner state of the body.
at least biological rhythms
This is a tricky question. This is where homeostasis takes part.
As we know before, that homeostasis is a fine-tuned balance between input and output, we could hypothesize that the function of the brain, from the complex, to the balancing, and even the circadian rhythms, will not work as we know.
Imagine circadian rhythm as a wheel spinning on its axis. The axis, known as homeostasis, functions to keep the wheel going not to fast as to fly leaving its axis, and to slow in dropped from its axis.
Suddenly, the axis disappeared. The thing that is supposed to control is now missing. The wheel could fly as a saucer, or drop to ground as a potato.
Hence the circadian rhythm (and almost everything else, I guess).
if some data on the subject exists from a real-world observation/research
To date, it is impossible to achieve a state of input-less brain or so, since it would kill the brain in the process. Even if so, the brain would go uncontrolled, and it minutes, a series of catastrophe will send the brain into a state of death.
I myself had witness a gruesome "sneak peek" of input-less brain.
Since homeostasis is part achieved by integration, what happens when the integrator itself, crushed?
- I witnessed an accident back ago when a person's head was crushed by a truck. The persons body trembles like a fish out of water for some moment (a long one) before shuts down.
- By crushing the integrator, we almost could achieve a state of input-less brain, since the brain cannot receive any input. Hence the output goes crazy, because the axis (homeostasis) itself was lost.
in case a person was born without any inputs
Development is a thing very subtle to change. Even a small change could cause into a catastrophe leading to miscarriage. A defect in sensory input of an embryo's brain will lead to aberrant integration and output (another theme of homeostasis), hence the embryo's brain will stop functioning (and growing) normally.
Imagine an embryo's brain as lazy mailman.
"I only work when I see a mail around"
-If the mail is not coming for a long time, we could know that, the mailman eventually doesn't give any care again about the mail, hence there is no sending, etc.
The brain degenerates.
deduction from our knowledge of how the brain works
The Neuroscience is a science of integration, by to date, deduction by single neurons and how they work is possible, but how they work together, is still impossible.
To answer your question, we need to expand our rudimentary knowledge about our brain, from its components, to the machinery.
We only know how the component works, but we still don't know how the car works.
I realized I invested 45 minutes for this.
I also edited this answer 1 time for a total of 13 minutes.
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