"Simulated" visual, auditory and tactile sensation.

[FeloniousMonk]

Hi all, this is my first post here. I am a layman and this question is inspired by my curiosity about music and perception thereof particularly, but encompasses more than that.

 

First, I'd like you to recall your favourite song. You will probably "hear" the correct intervals between the notes (even if you don't get it in the right key), the approximate rhythm, and the correct octave placement of each note. You can hum it out loud, tap your feet to the rhythm, perhaps even harmonise with that imagined music.

 

My question relates to that experience- the experience of simulating that memorised musical phrase, or perhaps embellishing it. When you do this, is it "sensing", or not? If so, what is being sensed? Without meaning to inappropriately stain this question with religious dogma, I think it would be interesting to look to eastern (primarily Buddhist) conceptions of sensing, as they count "mind" as being a sense. Could such a view be sustained in light of what we know to be the case about the brain?

 

To take a further departure, my father has schizoaffective disorder. I'm interested in the nature of his auditory hallucinations. On a physical level, what differs between our simulation of a sound, and the auditory hallucination of sound/s people with certain psychopathologies experience?

 

I'm becoming acutely aware of how disjointed my questions are, so I'll attempt to summarise them in clear fashion:

 

1. How do we simulate visual, auditory and haptic sensation?

2. Does such simulation in any meaningful way qualify as a "sense"? That is, are we "sensing" that simulation?

3. How does pathological hallucination differ from normal simulation in terms of brain behaviour?

 

Thanks.

[iNow]

Hi FeloniousMonk - Welcome to the community. Interesting questions, too. At it's heart, I think this is a question about our definitions and how we subjectively use terminology. When we hear music, it is sensed through activation of the nervous system. Our nerve cells are firing little electrical signals, and that combined event is what we holistically describe as "sensation."

 

When we recall an event, or when we replay music in our minds, it's really those same nerve cells that are firing and allowing us to have that experience. We are still perceiving it much as we would when there is actually music being played, it's just that the cause of that nerve activity is different. In one case, the cause is pressure waves from the air coming into our ear and causing little tiny hairs called "cilia" to bend. When those cilia bend, it creates an impulse through the nervous system. When we merely imagine that music, we simply trigger it with conscious thought, or sometimes the music comes to us unconsciously (like when a song gets stuck in our head). We don't yet fully understand consciousness, but the idea is that those same cells are firing allowing us to have the experience of "hearing" or "feeling" music... It's just that their proximate cause is different.

 

Whether or not we call it a "sense" is, IMO, arbitrary. We could call it magical transcendent experience or we could call it a strange quirk of nature and evolution. The point is that the signal of the event is itself like music... The patterns and waves of neural activity through the brain are playing the same notes and the same melody. Nerve activity is very similar to music, but I digress.

 

With hallucinations, it's basically the same thing, but the nerve activity is more chaotic and less focused or directed as it is in a non-hallucinating brain. Many psychopathologies are the direct result of strange neural wiring and firing. It all happens on the same underlying substrate or infrastructure, but the nature of the activity is different.

 

 

The following website has an awful title, but a lot of really great content. You might check it out and explore more for yourself: http://faculty.washington.edu/chudler/introb.html

[FeloniousMonk]

Thanks a lot for the substantiative answer and the link.

[iNow]

1. How do we simulate visual, auditory and haptic sensation?

Looking at this from another angle, we could apply direct electrical stimulation to the brain in precise locations and intensities and trigger the response that way. There is a lot of research with direct brain stimulation... everything from causing an individual to think they are in a room with god to helping quadriplegics move a cursor on a screen or a robotic arm with their thoughts alone. There is no reason IMO why the same type of technology could not be used to "stimulate" the perception of music... We're just not advanced enough with the technology yet, but it's feasible.