4
$\begingroup$

We know that, for example, during brain surgery, electrical stimulation in certain parts of the cortex is sufficient for experience, and result in reportable experiences in human subjects.

We also know that action potentials are not sufficient to cause experience when they occur in other parts of the body. For example, as far as I know, humans are not aware of action-potential-caused insulin release in the pancreatic cells.

Further we know that mechanical stimulation of the fingers is converted to action potential trains, then relayed via interneurons, and is subsequently reported as touch. The situation is similar with other senses.

But, are there any examples of reportable experience without preceding action potentials? In other words, are there any cases of experience that is not correlated with electrical activity?

I'm interested because my deeper question is "Does all qualia result from action potentials?"

$\endgroup$
  • $\begingroup$ One of the common arguments against the value of the qualia concept is that introspection is notoriously unreliable. So the bigger question is, if there were reports of experience without electrical activity, would we believe them? Such reports are common for example in near-death experiences, suggesting that people experience qualia during periods of "brain death", but evidence suggests otherwise. $\endgroup$ – Arnon Weinberg Jul 18 '15 at 20:51
5
$\begingroup$

It is generally accepted that all activity having to do with conscious experience is mediated by spiking in the cortex. Sub-threshold activity, such as excitatory postsynaptic potentials (EPSPs) are not carried forward in the nervous system and will 'fade' before having an effect. It all revolves around action potentials.

Quoting from Kandel et al. (2000):

Action potentials constitute the signals by which the brain receives, analyzes and conveys information. These signals are highly stereotyped throughout the nervous system [...]. The information conveyed by the action potentials is determined not by the form of the signal but by the pathway the signal travels. The brain analyzes patterns of incoming electrical signals and in this way creates our everyday sensations of sight, touch, taste, smell, and sound.

Reference
Kandel et al. eds. Principles of Neural Science, 4th ed. McGraw-Hill, 2000

$\endgroup$
2
$\begingroup$

I think it is safe to say that we simply don't understand nearly enough (anything?) about the neural basis of qualia / experience to be able to give a satisfying answer to this question. That said, at least in the case of human experience, most neuroscientists would agree that if there is any centralized locus of experience it is the brain, and although the brain does have some non-action-potential "commerce", a great deal of it is through action potential mediated communication; I would find it hard to believe that it wasn't involved in conscious experience.

More importantly, being able to test whether one could be consciously experiencing while silencing 100% of action potentials seems like a rather tough experiment to do, given that doing that would probably kill the subject (such as with tetrodotoxin poisoning).

$\endgroup$
  • $\begingroup$ IF there is one centralised locus of experience, yes, then it is most likely the brain. Yet for the sake of diversity of arguments (and because I find the following book convincing) I'd like to point to Alva Noë's book 'Out of our heads' in which he argues against the widely occurring almost exclusive focus on the brain in the endeavour to understand consciousness. Surely, the brain is necessary for conscious experience but not sufficient. $\endgroup$ – bunsenbaer Jul 18 '15 at 18:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.