FDR corrected t -tests were used as post-hoc tests. Likert scale values in the RHI questionnaire values are organised as ordinal data. Therefore the best suited analyses are the non-parametric ones. The ICQ are questions not related to the illusion, that could be considered as a measure of the participant response bias, namely the tendency of participants to give the answers that they think could be in accord with the experimenter expectancy. This consideration is also supported by the empirical observation that in the majority of RHI experiments, if the illusion is present, the IRQ have higher values while the ICQ have lower values Botvinick and Cohen, ; Aimola Davies et al.
Therefore, to understand if an illusory effect in a condition was present, testing IRQ vs. ICQ could be an effective test. However, testing IRQ vs. In order to understand if the illusion was present in specific conditions, we used the non-parametric Friedman's ANOVA. Then we analysed the three groups Healthy, Paraplegics and Tetraplegics separately with the same analysis. Thus, we assessed two dependent variables for each condition, namely: In Figure 2 a graphical representation. Drifts in the position of the participants hand in the various conditions. Post-hoc t -tests FDR corrected were computed, comparing Synchronous vs.
Asynchronous stimulation for each Body Part and Group. The Friedman's tests were still significant after dividing the analysis according to the groups Healthy group: This result indicates that the three groups have different values in the RHI questionnaire in the different conditions. For a graphical representation, see Figure 3. The illusion according to participants responses to the questionnaire.
The differences between responses in IRQ and ICQ mean values and standard errors in the three groups are represented for each condition. SCIM-3 values are reported in Table 1. This study explored whether RHI which involves a process of integrating visual and tactile input may constitute a reliable proxy for exploring and understanding the plasticity of bodily representations in people with SCI who suffer from massive disconnection of the body from the brain.
There were three new, potentially important findings. The first is that the level of the lesion seems to influence the probability that the RHI will occur. More specifically, the more massively disconnected Tetraplegics group showed indices of ownership of the fake hand, as inferred from the questionnaire, both in the Hand Synchronous and Asynchronous and in the Face-Synchronous conditions.
The less massively disconnected Paraplegics group showed subjective indices of RHI only in the two Hand conditions. Finally the Healthy group showed the illusion exclusively in the Hand-Synchronous condition. This picture indicates that the ownership component of RHI is related to different degrees of disconnection-related, topographic plasticity. The second finding is that the index of perception of body in space, as inferred from the drift, was found only in the Healthy group and only in the Hand-Synchronous condition.
This suggests that this component of RHI is profoundly altered by somatosensory and motor body-brain disconnection. Moreover, in its canonical description, the manifestation of RHI requires not only synchronicity of stimulation but the rubber hand must also be congruent with the real one in terms of position and identity Tsakiris and Haggard, ; Zopf et al. Studies also indicate that the RHI may be stronger in the vertical version i. By adopting the vertical version of the RHI paradigm, we confirmed that in healthy subjects the phenomenal component of RHI is triggered by synchronous hand stimulation.
Significantly, we demonstrated that for participants with SCI this component of RHI is greater in people with a higher level of the lesion who suffer from more massive deprivation. Our result is in keeping with the direct demonstration of possible across-body parts remapping in people afflicted by SCI. For example, in tetraplegics who move a body part with intact representation e.
In a similar vein, shifts of the cortical sensorimotor representations of intact body parts toward disconnected ones have been reported after SCI Kokotilo et al. The Face-Hand illusion effect found in tetraplegics but not in paraplegics and healthy people may thus be interpreted as a perceptual index of topographical cortical and subcortical remapping Freund et al.
The increased sense of ownership of the fake hand as indicated by the questionnaire expands our previous study reporting a comparable effect in SCI and healthy subjects Lenggenhager et al. Moreover, our study contributes to previous studies showing feeling of ownership may occur not only after synchronous stroking but also after asynchronous stroking Rohde et al.
Indeed in our study the subjective sense of ownership of the fake hand was induced in SCI groups even in the asynchronous hand stimulation condition. The fact that somatosensory deficits of the hand being stimulated did not correlate with the participants reports in the questionnaire suggests that the integrity of tactuo-proprioceptive information likely driving bottom-up modulations does not influence the questionnaire component of the RHI. Thus, we suggest that top-down modulations, exerted as a result of observing the fake hand, mediate the embodiment of the rubber hand and the projection of sensations onto it.
This may be in keeping with studies using the mirror box illusion in which amputee patients experience ownership of a rubber hand seen in a mirror in the absence of tactile stimuli on their intact hand Giummarra et al. In a similar vein, studies on brain damaged patients indicate that the mere sight of a rubber hand brings about a sense of incorporation of an alien hand Fotopoulou et al. RHI experiments on healthy subjects typically demonstrate robust proprioceptive drifts that have been considered a strong behavioral proxy to embodiment Botvinick and Cohen, Interestingly however, healthy subjects may not only report the drift when they are asked to judge the position of the finger that has just been stroked, but also report the misallocation of an adjacent finger Tsakiris and Haggard, Thus, although tactile information is very important in terms of inducing the drift, top-down modulations of bodily representations may also influence this component of RHI.
In line with this, it has been suggested that the drift occurs only when the observed rubber hand is congruent in terms of posture and identity with the participants unseen hand Tsakiris and Haggard, Measurements of the perceived localization of the participants hand before and after the various different stimulation conditions indicate that, unlike the healthy controls, the SCI subjects did not show any proprioceptive drift. This result is different from what was reported in a previous study where the perceived localization of the body in space, as indicated by the drift, was maximal in SCI patients with defective tactile sensations in the stimulated hand Lenggenhager et al.
While no ready explanation for this somewhat paradoxical result is currently available, one may hypothesize that the relative somatosensory impairment of the fingers stimulated in the Lenggenhager et al. It is worth noting however, that the two studies cannot be easily compared. There is a clear difference between the two paradigms related to the position of rubber hand relative to real hand which was vertical in the present study, while horizontal in Lenggenhager et al.
Moreover, the criterion used for detecting drift is here more conservative. Finally, the clinical severity of the Tetraplegics group seems to be greater in the present study. At any rate, a tentative explanation for the absence of drift found in the present study is related to the notion that, under physiological conditions, the stable representation of bodily self is dynamically updated by incoming sensory-motor information Head and Holmes, Thus, we posit that in SCI subjects the interruption of the somatic body-brain connections may induce a bias toward a predominance of the top-down e.
The debate about the processes underlying the RHI is still very vigorous.
Original Research ARTICLE
While the illusion was originally thought to be an effect of the dominant role of vision in intermodal integration Botvinick and Cohen, , subsequent studies suggested that it may be induced by other objects than a fake hand and thus stem from a bottom-up Bayesian perceptual learning process rather than from a process of embodiment and change in body self-representation Armel and Ramachandran, but see Tsakiris and Haggard, In addition, a recent study demonstrates that the RHI can be induced by the mere observation of an object approaching the rubber hand but without touching it Ferri et al.
Studies on healthy subjects suggest that the two RHI components indicating ownership of an artificial hand and the illusory perception of the body in space hand drift do not go hand in hand Rohde et al. In particular, we posit that the illusory ownership as assessed by the questionnaire may be related to mainly visual, top-down modulation while the proprioceptive drift may be based on bottom-up information processing. Thus, while post-deprivation neural plasticity may amplify illusory ownership in SCI subjects, the lack of afference and bottom-up information may cause lack of drift.
Although the RHI is largely used as a direct index of body-ownership, studies demonstrate an elevated inter-individual variability in the effect Haans et al. Moreover, the fact that the mere sight of the rubber hand triggers the RHI more than the tactile sensation does Pavani et al. However, no relationship between the indices of RHI and the results of the personality and susceptibility tests was found in our sample, suggesting that studies with a larger sample are necessary to demonstrate whether the absence of evidence really means that this relationship does not exist.
In a previous study on SCI subjects Pernigo et al. As a result we reasoned that in this study the degree of functional autonomy which is mainly linked to the extent of the lesion might influence the effects of the RHI. However, no correlation between these two variables was found. While this negative result may suggest that the visual perception of other people's bodies and RHI are largely independent phenomena, further study on this issue is necessary to explore the link between RHI and somatosensory and motor deprivation.
Further insights about face-hand remapping may be revealed by the stroking of different body parts.
At the end of each experiment we asked to the participants if they felt any particular sensation that was not captured by the questionnaires or if they had any additional comments. Normally no sensations and no comments were referred, except in three cases. One tetraplegic participant T6 reported that in the middle of the Face Synchronous condition he started to feel the touch on the hand that was usually insensible to touch since his spinal cord lesion, 30 years earlier. At the end of the experiment he tried to touch the rubber hand with his own right hand to test whether he could feel the touch again.
Another tetraplegic participant T5 reported that, starting from the first hand condition, every time we touched the rubber hand with the Q-tip, he felt a light pain sensation at his own hand, that he located at the rubber hand position and not at the real hand position. His real hand was insensible since the traumatic lesion of the spinal cord, 13 years earlier. A paraplegic participant P14 , reported that, during the Face conditions, the mere vision of the rubber hand was strong enough to feel the embodiment sensation, but the tactile stimulation at the left cheek interrupted this illusion.
The subjective report of T6 seems in line with our result that in Tetraplegics also facial stimulation can evoke ownership illusion, while T5 shows the presence of illusion in both the synchronous and asynchronous Hand conditions.
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The participant P14, instead, suggests that, in some people, mere vision of the Rubber Hand may cause the illusion, interrupted by the tactile stimulation, similarly to what was observed by Rohde et al. Some possible limitations of this study deserve discussion. The variety of the NLI levels and in the time interval between the lesion onset and the experimental session in both the Tetraplegics and Paraplegics groups are relevant. These differences imply each individual in the same group does differ in motor, tactile and proprioceptive functions that surely have effects on neuroplastic somatosensory and motor cortical changes.
These differences are even more striking in the Tetraplegics group, where a difference among C4, C5, and C6 greatly impact in the possibility of arm movements, from the complete paralysis to the possibility of motion and use of tools. It is also worth noting that more chronic SCI subjects could have learned a higher number functional strategies than a less chronic SCI subject. This should have neuroplastic consequences. Furthermore, even if there are not statistically significant differences between groups, the fact that some Tetraplegics could feel the tactile sensation of the Q-tip in the hand, while other participants could not feel it, probably have some influence on the results of this study.
Finally it was not possible to have the MRI scans before and after the SCI thus our suggestions regarding the influence of lesion onset, tactile sensitivity and neuroplastic changes remain speculative. However, finding significant effects in spite of the above reported characteristics of heterogeneity could be an indication of robustness of the effects themselves, thus our results are in keeping with the typical neuroplastic changes following SCI reported in previous literature Bruehlmeier et al. Infected parents, researchers found, have a 30 percent chance of passing the parasite on to their children.
If that all seems a little far from home, though, consider this: Researchers estimate that more than 60 million people in the U. Until the day it strikes, that is. These inviting little ponds often play host to Naegleria fowleri , an amoeba species with a taste for human brain tissue. When a cyst comes into contact with an inviting host, it sprouts tentacle-like pseudopods and turns into a form known as a trophozoite.
Damage black cavities caused by Naegleria fowleri as seen in a brain tissue sample. As the amoeba divides, multiplies and moves inward, devouring brain cells as it goes, its hosts can go from uncomfortable to incoherent to unconscious in a matter of hours. The symptoms start subtly, with alterations in tastes and smells, and maybe some fever and stiffness. But over the next few days, as N. Next come seizures and unconsciousness, as the brain loses all control. A dog suspected of being rabid that had been exhibiting signs of restlessness, and overall uncharacteristic aggressive behavior.
In the altered states brought on by a rabies infection, animals often lash out at any nearby living thing, but this may be more out of fear than anger. Human rabies patients become terrified of water and puffs of air , both of which make them flinch and twitch uncontrollably. If the infection goes untreated, rabies patients fall deeper into confusion and hallucination, lashing out at imagined threats and hapless bystanders. They lose their ability to sleep, sweat profusely, and finally fall into a paralyzed stupor as their brain function slips into chaos.
A few days later, as the paralysis reaches their hearts and lungs, they fall into a coma and die. Once rabies has infected a human, survival is all-but impossible. To date, fewer than 10 people have survived a clinical-stage rabies infection — ever, in history. Many doctors consider the disease untreatable.
In the villages of sub-Saharan Africa and the wilds of the Amazon, the tiniest insect can bring a sleep that leads to death. The tsetse fly loves the taste of human blood, and it often carries a parasite known as Trypanosoma , whose tastes run more toward human brains. Parasites of the genus Trypanosoma start their lives in the guts of invertebrate hosts, but quickly develop through a series of increasingly complex forms when they come into contact with the mammalian fluids they crave.
Trypanosoma lewisi flagellate parasites red, hooked cells in a blood sample maginfied x. As they mature, the parasites cross the blood-brain barrier and the encephalitic stage begins. Before long, though, human hosts start to exhibit a dizzying variety of other psychological symptoms, from changing appetites to depression to odd speech patterns to uncontrollable itching and tremors.
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Scientific fact, as so often happens, is stranger than fiction when it comes to these parasites. From worms that devour brain cells to viruses that bring on crippling paranoia, these creatures are every bit as ghoulish as those in any fireside ghost story. The mere idea that Toxoplasma gondii causes cultural mental diseases curable with azithromycin or pyrimethamine plus sulfadiazine makes a mockery of psychology and psychiatry. It must be vigorously suppressed lest respected professions be revealed as beads and rattles.
You are absolutely correct Uncle Al. Psychiatry uses a single hammer, and that is psychotropic drugs. When one does not work, they try another. The almost never consider the possibility of T. I am a victim of psychiatry. It took years for me to develop the insight to convince a trained veteran psychiatrist to accept my diagnosis.
At one point I was prescribed Thorazine, and this continued with no benefit to me for years. I suffered tardive dyskinesia, and the psychiatrists remained obdurate. Now, I am being treated with Buspirone and Strattera. I have a lot less problems as a result, but I am 44 years old, so the solution came a little late for me. I do find it interesting, there has been a spike in depression and Toxoplasmosis is about. The real issue is the ability of a psychologist or psychiatrist to diagnose symptoms.
People have their own biases, and what I found is that most psychiatrists go on the word of other psychiatrists, so there is often no examination performed. So, in her case Dr. Trixi Lipke was able to fellate her way to success. Malpractice insurance premiums are so inordinately high, because you have literal idiots practicing medicine.
In other forms of medicine they have tests they can perform, although there are a battery of psychological tests, the results are subject to the inherent biases of the interpreter. Yes because ideas in science are dangerous, especially ideas that attach any sort of risk to having a cats as pets. Toxoplasmosis cannot be cured, because it has a cyst form that cannot be killed by any drugs, and there are always a few cysts in any infection. The best the drugs can do is force an active, symptom causing case into submission by killing all the active parasites in the system.
Only immunocompromised, the old, the sick Etc. For the vast majority it is a symptom free infection after a possible mild initial infection response. The fact that it is symptom free for the most part makes taking those horrific antibiotics you so casually mistakenly mention as cures for treatment simply not worth the agony they cause most people in the developed world.
Perhaps the proof that gondi can control and direct human behavior can be found in you. Your comments on the parasite, and comments defending cats their true host against anything that might be construed as negative certainly is in their best interests of the parasite. The drugs he listed are actually in fact the recommended treatment for toxoplasmosis, though. Azithromycin is a very well tolerated antibiotic, in fact. And this is from someone who detests taking antibiotics.
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I will do almost anything before I take antibiotics. I agree — hate antibiotics, but I was so over-prescribed when I was younger I am now resistant to all of them except Ertapenum.
If you want to know what aliens will be like, just look at an octopus
So I live with a sinus infection and an infection in my eyes all the time. It is illuminating to read the response to your supposition, Uncle Al. Not sure I understand your comment. I think those two professions will have to get in gear about Toxoplasmosis. Toxoplasma plays far more widespread roles in our lives than we think, I think. But the octopus nervous system is much poorer in the fast, long-range connections that connect the regions of the human brain.
This suggests that the integration of the activity of different brain regions might be very different in octopuses. At the neural level we know little about octopuses. If they are conscious, what might they be conscious of? Human conscious content ranges from those associated with sensations of the outside world to feelings, thoughts, experiences of volition and will, and many others. The classic human senses are vision, hearing, touch, taste and smell, which are accompanied by important sensory channels, including senses of body position and movement, pain, temperature and a raft of inputs on the internal state of the body.
In terms of sensory capabilities, all octopuses have good vision, even for the low light conditions prevalent at night or on the ocean floor. They also share the senses of taste, smell and touch; they can hear but not well.
The Alien awakened by a rubber hand
Octopus arms are rich in sensory receptors, used for touch and taste. Of the sensory channels, we know little but we do know they have pain receptors and show a range of pain-related behaviors similar to vertebrates, like grooming and protecting injured body parts. When we perceive our environment with vision, we do more than build an accurate picture of an objective reality.
Instead, we perceive the world in terms of how we might act in it and on it. A door, for instance, is perceived as something that can be opened by us, not just as a rectangular slab of wood. A crucial feature of human consciousness is the variety and sophistication of our self-consciousness.
The Alien Brain Rubber - Kathy Haveron - Google Книги
These include a basic sense of being and having a body, experiences of looking out onto the world from a particular first-person perspective, and experiences of volition and will. Even here on earth, being a conscious self may involve types of sensation that are completely alien to us humans. Altered body experience can sometimes be induced. If both hands real and rubber are simultaneously stroked with a soft paintbrush, most people have the bizarre experience that the rubber hand somehow becomes part of their body.
This shows that our experience of what is — and what is not — part of our body is not simply given but is a surprisingly flexible perception generated by our brain. Studies have shown that they are capable of behaving semi-independently and can execute complex grasping movements even after being severed. This suggests that the octopus may have only a hazy experience of its body configuration. In fact, there might even be something it is like to be an octopus arm. For an octopus, the suckers on each arm automatically grip onto almost any passing object, but somehow they do not fix onto its other arms or central body.
One way to achieve this feat of self-discrimination would be for the central brain to maintain an up-to-date picture of the position of each limb. Human brains can do this.