Medical Can someone explain the neuroscience conjoined twins?

  1. Twins conjoined at the head
    Brains conjoined, thalamus connected
    They are aware of each other's thoughts
    They can see out of each other's eyes

    What the heck? Someone explain this. I'm having major cognitive dissonance trying to fit this into my worldview.
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Drakkith

    Staff: Mentor

    Not sure what to tell you. What about it didn't you understand?
  4. Evo

    Staff: Mentor

    No, I doubt are not aware of each other's thoughts and they cannot see out of each other's eyes. This is all speculation. I'll be surprised if future testing once they get older will substantiate what the mom thinks. Maybe I'll be wrong, but it's not unusual for babies to sense things and appear to have miraculous reactions to other babies near them.
    Last edited by a moderator: Sep 25, 2014
  5. The science behind it. The video says they have a connected thalamus, but I don't know what that means. My understanding from the video is that we have two different "persons" whose brains are conjoined and so they can essentially file-share info.
  6. The mom thinks they are aware of each other's thoughts. That they can see through each other's eyes is undoubtedly true, though it might be more accurate to say that each one can process the visual info from the other.
  7. Evo

    Staff: Mentor

  8. The two girls are in a sense separate entities in that their bodies are separate -BUT both girls perceive both bodies, hence they are one 'whole' in a perceptual sense with two minds. The real separation is in the aspects of the brains of each girl that are unique. Each has already begun to develop a separate 'personality', a way of assimilating the perceptions of the 'whole' from their own perspective.
    Each person's way of being is a matter of choice. In the case of co-joined twins, especially ones sharing as much as these two do, their lives will necessarily be co-joined.
    I doubt that they will have any problem accepting who they are. It is the 'average' or -my euphemism- 'bubble baby' humans that will have problems accepting 'alien' AKA 'foreign' perspectives.

  9. To Evo,
    just a quick note, I watched the clip again and just at the end the mother makes a reference the the test where the eyes of one child were kept closed and EEGs registered response to the flash of light in the other girls open eyes. This response is indicative of a neural connectivity equally seen in the other tests shown on the clip. The mother is right in saying their connection is greater than other inter-cranial co-joined twins but 'thought' is clearly a personal matter that I am sure we both agree is not capable of transference/translation -mind to mind.
    p.s. an afterthought- almost lost it -memory going- the girls were talking to each other to convey what they wanted the other mind to do not 'thinking' the message through.
    Last edited: Mar 25, 2013
  10. Ryan_m_b

    Staff: Mentor

  11. You may be interested in patients with split brains too, then:

    The thalamus relays a lot of sensory information to higher brain areas, so it makes sense that, if their thalami are connected, then they will receive a certain amount of sensory information from the other twin's body in their higher brain areas (i.e. where consciousness happens). Though of course it could be the case that, though the thalami are joined into one entity, there aren't actually many connections between neurons there, so it's difficult to say from gross anatomy how it should affect their sensory perception and thought. It will be very interesting to see what happens later in development - over the course of adolescence, the brain gets rid of a lot of connections between neurons, so I wonder how this will affect the connection between the two brains.

    Consciousness is an odd thing...
    Last edited by a moderator: Sep 25, 2014
  12. Ygggdrasil

    Ygggdrasil 1,825
    Science Advisor

    The amazing thing about the human brain (and the brains of other higher mammals) is that most of the wiring to interpret and convey signals is not genetically pre-determined, but rather forms in response to the simuli it experiences. For example, there is nothing that predetermines the visual circuitry to receive input from only two eyes. If you take mice and deprive them of any visual stimuli after birth, the circuitry in their brain for interpreting visual stimuli will not develop properly. So, if an individual is born with one brain connected to two sets of eyes, the visual processing areas of the brain will wire itself to be able to process the signals from all four eyes.
  13. Wow, this is really interesting stuff. I just hope the girls remain healthy and they and the mom remain amenable to a continued longitudinal study of their development. The potential window into development of consciousness and cognition here is unrivaled and rare. I haven't looked into yet further than just the video, but I couldn't have invented a more interesting cog-neurosci experiment...Two conjoined twins sharing only a thalamus. Unimaginable.

    The one interesting thing that immediately struck me in the video was the locomotion these girls displayed. It almost looked like a three-legged race. It did look like a single brain was coordinating the global movement. I'm not an expert on conjoined twins, but I haven't seen other twins of this sort coordinate their movement in that way. I think the light and pain tests they show in the film confirm that the joined thalamus is indeed sending cross signals to each girls cortice. What is most going to interest me about these girls is going to be their language development. I can't imagine how that is going to play out.
  14. Evo

    Staff: Mentor

    Are you familiar with the twins Abigail and Brittany? Although each girl only has on leg and one arm, they can walk, run, ride a bycycle, swim, drive, etc... It is truly amazing.

    Attached Files:

  15. Ryan_m_b

    Staff: Mentor

    Not to mention they can drive. Although its strange that they had to take two driving tests considering they are both driving.
  16. The only aspect I am able to grasp are the twins acoustical world. Take a look at the 'xylophones'.
    This is called tonotopy.

    Everyone shares this common tonotopy and the differences arising from structures are minimal. You can sure be everyone 'hears' the same thing until of course such information reaches the brain(s) where the process to distribute (and store) this information is as unique as the brains processing the information - everyone assigns their own associations to the same physical phenomena.

    You can 'close' the hearing of one of the twins and the other twin's ears will become the perfect substitute.
    The twins have double 'awareness' - the senses are doubled. A single brain with double the sensory input will take this in stride - nothing unusual as far as a single brain is concerned.

    My world as far as the twins are concerned remains intact taking the twins and their heighten experiences in stride. We - my twin and I - started out with less - without co-union. We shared less than the twins reported here.
  17. What about this baby with no brain? Is it conscious?

    Last edited by a moderator: Sep 25, 2014
  18. The news is very misleading. The kid obviously has a brainstem, which is needed for respiration. The eyes, tongue and mouth move so some of the cranial nerves work. The information process part is probably not functioning but who knows.
    Last edited by a moderator: Sep 25, 2014
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