Medical How logisticlly are imaginary images formed in the brain?

[Thenewdeal38]

Is it a collage of interacting nuerons and the cohesive accumulation of information? Or something else, don't tell me its dependent on quantum proporties?

 

[Ryan_m_b]

I have no idea what you are trying to ask here, could you phrase your question better? I suspect that you are asking if quantum effects are necessary for conscious perception. That being the case I have to inform you that the case for quantum mechanics being necessary for consciousness has not been made.

As for how biological processes give rise to consciousness I'm afraid the answer at the moment is we don't know. This is called the hard problem of consciousness and seems likely to be with us for a long time yet.

 

[zoobyshoe]

Is it a collage of interacting nuerons and the cohesive accumulation of information? Or something else, don't tell me its dependent on quantum proporties?

In Musicophilia Oliver Sacks reports that brain imaging shows the same areas becoming active when imagining music as when actually listening to it. (This suggests, incidentally, that memory is a kind of degraded replay of the original experience.)

A quick google turned up a paper which comes to the same conclusion for visual imagining: when you are visually imagining, the same areas become active as are active when you're actually looking at real things:

http://web.mit.edu/bcs/nklab/media/pdfs/OCravenKanwisherJOCN00.pdf

(They reference a lot of other studies, so, apparently this is a question that is receiving a fair amount of attention.)

So, the answer to your question is that imaginary images are as logistically formed as actual perceptions.

 

[atyy]

In Musicophilia Oliver Sacks reports that brain imaging shows the same areas becoming active when imagining music as when actually listening to it. (This suggests, incidentally, that memory is a kind of degraded replay of the original experience.)

A quick google turned up a paper which comes to the same conclusion for visual imagining: when you are visually imagining, the same areas become active as are active when you're actually looking at real things:

http://web.mit.edu/bcs/nklab/media/pdfs/OCravenKanwisherJOCN00.pdf

(They reference a lot of other studies, so, apparently this is a question that is receiving a fair amount of attention.)

So, the answer to your question is that imaginary images are as logistically formed as actual perceptions.

Interesting! They concentrate on extrastriate visual cortex - I wonder if they know what the result is for striate cortex?

 

[zoobyshoe]

Interesting! They concentrate on extrastriate visual cortex - I wonder if they know what the result is for striate cortex?

I do not know. I actually have no idea what "extrastriate" means.

 

[atyy]

I do not know. I actually have no idea what "extrastriate" means.

Looks from wikipedia like striate cortex is primary "lower" visual cortex, while extrastriate refers to "higher" visual cortical areas. Roughly, it makes sense that imagining is "reactivating" "higher" visual areas, and not "lower" visual areas such as the retina. But since there are so many levels (is it even hierachical?), I don't know where the cut between "higher" and "lower" is with respect to visual imagination. I was wondering if they didn't do striate cortex just because they knew the cut was above it?

I believe people have searched for "attentional effects" in striate and extrastriate cortex, but so far those have only been found in extrastriate cortex.

Oh - what about phantom limb - that's some sort of imaginary perception isn't it? Let me google what Ramachandran says about this.

Well, wikipedia says Ramachandran was inspired by results in primary somatosensory cortex. Of course, his successful predictions based on the theory don't mean that the theory is right. But tentatively, it seems even "low" level sensory cortex could be involved in some sort of "imagination", if we count phantom limb.

 

[zoobyshoe]

I was wondering if they didn't do striate cortex just because they knew the cut was above it?

The choice of areas seems based on their known selective responsivness to either faces or place scenes, not on their "highness" or "lowness":

Our study exploited the perceptual selectivity of two recently described extrastriate areas, and asked whether these areas exhibit a parallel selectivity during mental imagery. A region of ventral occipito-temporal cortex called the fusiform face area, or FFA (Kanwisher, McDer- mott, & Chun, 1997), responds strongly when subjects view photographs of faces, but only weakly when they view other classes of stimuli such as familiar objects or complex scenes (McCarthy, Puce, Gore, & Allison, 1997; Puce, Allison, Asgari, Gore, & McCarthy, 1996; Haxby et al., 1991, 1999). Conversely, a ventromedial cortical region called the parahippocampal place area (PPA) responds strongly to images of indoor and outdoor scenes depicting the layout of local space, but not at all to faces (Epstein & Kanwisher, 1998). These two regions provide an ideal arena for testing the selectivity of cortical activations during mental imagery because they exhibit opposite response properties: the optimal stimulus for the FFA is a very weak stimulus for the PPA and vice versa. Thus, we were able to look for a double dissociation of brain activity in response to imagery of two different classes of stimuli, instead of comparing imagery to nonimagery tasks as most previous studies have done.

I would imagine, therefore, that the primary visual cortex (striate) is too responsive to too many stimuli to serve their purpose here.

 

[atyy]

The choice of areas seems based on their known selective responsivness to either faces or place scenes, not on their "highness" or "lowness":



I would imagine, therefore, that the primary visual cortex (striate) is too responsive to too many stimuli to serve their purpose here.

That makes sense.