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The presence of consciousness in the absence of the cerebral cortex


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The presence of consciousness in the absence of the cerebral cortex

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The presence of consciousness in the absence of the cerebral cortex

  1. 1. Article Lead Author: Beshkar, Majid Date: 2008 Article: The Presence of Consciousness in the Absence of the Cerebral Cortex 1. Pain felt at: a. If the article specifically asserts unborn children feel pain, at what post­ fertilization age? b. Page: 2. Nociceptors: a. Ifthe article states nociceptors are present, at what post-fertilization age? b. Page: 3. Thalamus link: a. If the article states nerves link nociceptors to the thalamus, at what post­ fertilization age? b. Page: 4. Subcortical plate link: a. If the article states nerves link to the subcortical plate, at what post-fertilization age? b. Page: S. Noxious stimuli reaction: a. Does the article refer to reaction to noxious stimuli? At what post-fertilization age? b. Page: 6. Stress hormones: a. Does the article refer to increase in stress hormones with noxious stimuli? At what post-fertilization age? b. Page: 7. Long-term effects: a. Does the article describe long term harmful effects from exposure to noxious st imuli? b. Page: 8. Fetal anesthesia: a. Does the article refer to use of fetal.anesthesia and its effect? At what post­ fert ilizati on age? b. Page : 9. Cortex: a. Does t he articl e relate t o the asserte d need f or cort ical involvement to exp eri ence pain? How?
  2. 2. b. Page: 553, Right Column, Last Paragraph. "However, there are some pieces of evidence that these children [with hydranencephaly] are able to experience at least some levels of consciousness." Page 554, Left Column, First Paragraph. "Shewmon et. al (1999) reported cases of four children aged 5-17, with hydranencephaly involving complete or nearly complete absence of cerebral cortex."
  3. 3. SYNAPSE 62:553-556 (2008) Short Communication The Presence of Consciousness in the Absence of the Cerebral Cortex MAJID BESHKAR· Tehran. University of Medical Sciences, Tehran, Iran KEYWORDS hydranencephaly; consciousness; vegetative state; behavior; cerebral cortex ABSTRACT Hydranencephaly is a rare neurological condition in which the cere­ bral hemispheres are either absent or severely compromised. It is widely believed that children with hydranencephaly are not conscious; and therefore, are routinely classi­ fied into the diagnostic criteria of vegetative state. However, ther~ are several pieces of behavioral evidence clearly indicating the presence of consciousness in such patients. Here, I review these behavioral evidence and argue how :qlisclassification of these patients and assigning them a lack of consciousness have far-reaching implica­ tions in terms of both clinical and theoretical neuroscience. Synapse 62:553-556, 2008. () 2008 Wiley-Liss. Inc. INTRODUCTION interrupts the visual radiations! for instance), and are Hydranencephaly is a rare neurological condition in not even locally functional. On autopsy, such tissuewhich the cerebral hemispheres either fail to develop may be found to be gliotic on microscopic examinationfor genetic-developmental reasons or are massively or to exhibit other structural anomalies indicatingcompromised by trauma of a physical, vascular, toxic, loss of function (Merker, 2007).hypoxic-ischemic, or infectious nature at some stage An infant born with hydranencephaly may initiallyof their development (Merker, 2007). The disorder, present no conspicuous symptoms and occasionallywhich occurs in less than 1 per 10,000 births world­ the condition is not diagnosed until several monthswide, is characterized by near-total or total absence of postnatally, when developmental milestones are mis­the cerebral cortex and basal ganglia. The thalami , sed. In the course of the first year of life, thesepons, cerebral peduncles, and cerebellum are usually infants typically develop a variety of complicationspresent, as may be a small amount of occipital-lobe, that always include motoric ones (tonus, spasticity,frontal -lobe, and tempor al-lobe tissue. The damaged cerebral palsy). Although survival beyond 6 months isbrain tissues undergo extensive resorption , and are rare with hydranencephaly, prolonged survival evenreplaced by cerebrospinal fluid filling otherwise empty up to 34 years can occur (Counter, 2007).meninges lining a normally shaped skull. Hydranen­ It is widely believed among neurologists that chil­cephaly must be distinguished from the even more dren with hydranencephaly are not conscious. How­severe neurological condition called anencephaly, a ever, there are some pieces of evidence that thesedisorder of the neural tube beginning very early in children are able to experience at least some simpledevelopmen t, which leads to virtually no brain devel ­ levels of consciousness (Fig. 1). Scientific literatureopment. about this issue is very poor, and there are only two The amount of brain ti ssue that each child with published accounts describing observations to thehydranen cephaly h s varies from child to child. Ma ny effect that children with hydranencephaly experienceof the children a re missing most of their brain ti ssues conscious states .above the brainstem. However, the loss of cerebralh eroisph res mu st be massive to be designated h ydra­ Corresponde nco to: No. 2, Sahel 1. Eas l Arghava n. Saadal Ab"rl , Tehron, I Iun . E~ ma l l: mnjid .bcs h klu-@yu hfJo.comnencephaly, although it. is seldom compl ete. While RI!ce;vec 23 Octuber 200"7; Accepl0Ji 20 .JflI1LIJrv ~OOt<,variable remnants of th ce rebral cortex m ay be o I 1n , 100:V.y 11 20 52,1spared, these coTtic I remnant are most proba bly n ot tu blil)h online 24 Apnl 2O(1B In Wiley 11lu;>r&iente hvwwinterscience_wilc;.­connected to the thalamus (whi te matter loss often L 11I lt l .1.)2008 WILlW-LlSS, INC
  4. 4. 554 M.BESHKAR arguments. For example, Merker argues that "Most animals and human infants mirror reactions are social reactions (that is, they treat the mirror image as a conspecific and NOT as themselves), so reacting to and being fascinated by a mirror by no means implies self-recognition. In the case of [this hydranen­ cephalic subject], we cannot even be sure that the behavior was of the nature of social reactions (though the smile raises that possibility); they might simply have been reactions to reflected movements and so on" (personal communication). Another child in this study exhibited discriminative awareness of the environment, for example, consis­ tently distinguishing close family members from others. At the approach or touch of strangers she assumed a fearful affect, became tense and withdrew, Fig. 1. Nikki, a hydranencepbalic girl, in the arms of her but relaxed to the touch and voice of mother. The mother. She has turned toward someone sitting on her left (you can more familiar someone was, the more she w(mld see the knee to the right in the picture). This picture shows the alertness of the girl, and her smile very well. For this picture, I am relax, move spontaneously, and vocalize. She was indebted to Bjorn Merker for receiving permission from Nikis aware of her mothers presence and became upset if mother on my behalf. separated. She had favorite pieces and types of music, to which she would consistently smile and vocalize, in contrast to other music, to which she consistently CONSCIOUSNESS IN HYDRANENCEPHALICS remained indifferent. Shewmon et a1. (1999) reported the cases of four Another child developed a liking for puppies and children aged 5-17, with hydranencephaly involving small children; and her face became animated when­ complete or nearly complete absence of cerebral cor­ ever she saw them. She also showed some orientation tex. The authors observed that these children pos­ capacities: when called, she would raise her head, sessed a variety of cognitive capacities that were in­ look at the person, and smile. Furthermore, when an dicative of ordinary consciousness, including person object she was tracking was suddenly taken behind recognition, social interaction (smiling when spoken her, she would turn in search of it. She was very to, giggling when played with, vocalization with socially interacting and clearly enjoyed being with music therapist), functional vision (object discrimina­ people and even played with them. The authors tion, fascination with own reflection), musical prefer­ observed that in an occasion the subject attempted to ences, orienting- toward and smiling at someone call­ imitate monosyllables and even uttered "ah-ah" whening, appropriate affective responses, goal-directed coaxed to say "mama." She also demonstrated somemotor behavior (scooting on back to reach a goal), and degree of body awareness. For example, if her face associative learning (using limited receptive vocabu­ hurt, she would stroke it with her hand. The mostlary to correctly look at an object)~ On the basis of interesting of her cognitive abilities was her capacitytheir observations, the authors concluded that each of of associative learning. The authors observed that shethe children they assessed was conscious by the crite­ startled and stiffened when a vacuum cleaner or hairria of a standard neurological examin ation . dryer with a loud unpleasant noise was turned on. One of thes children was able to visually interact Mter several such experiences, she also stiffened inwith the en vironment, scooting around the house anticipation if either object (though switched off) waswhile avoiding collision with walls and furniture . brought near. Moreover, she developed a small recep­More in teresting was the observation that he became tive vocabulary, including "bunny rabbit" (a stuffedfascinate d with h is own reflection in a mirror; and de­ toy), "Michael" (a family friend), and "Pocahontas"spite efforts to distract him, he kept turning back to (an image on her T-shirt); with coaxing and repetitionthe mirror, ex ploring it intently, and smiling. The of the question , "Where is [one of these]?" she cor­capacity to recognize oneself in the mirror is com­ rectly looked at the object or person.monly considered to be an indicator of self- a wareness, Another subject exhibited some limited form of non­an d is usually explored in animals by the so-called verbal communication by making cooing sounds,mirror test. This hydranencepha lic chil d wa appa­ expre sions of sadness or pai n , smiling in therently as interested in bis r fle tion as any in fant or presence of caregivers , an d indicatin g preferencesanimal that passes the m inor test. Although the through facial ex pression s a nd R broad smile. He wasauthors interpreted thi particul ar behavior as an in­ able to distingui h h is moth er s voice from that of hisdication of consciousness, ther are some> counteT­ fatherynapse
  5. 5. MO J" .. . ~t J I ," f, ,~ CONSCIOUSNESS IN THE ABSENCE OF CEREBRAL CORTEX In a recent article, Merker (2007) has described his seem to require reflective consciousness and self­ 555 ! first-hand observations of the behavior of hydranence­ awareness. However, it should be mentioned that j phalic children, as well as his impressions gleaned Merker used the term "consciousness" in its most ba­ i• from the reports of parents of such children. On the sic and general sense; and, in this context conscious­ I basis of his observations, Merker argues that "these ness is more than reflective consciousness or self­ children are not only awake and often alert, but show awareness. responsiveness to their surroundings in the form of Watkins and Rees (2007) argue that responsiveness ~ , emotional , or orienting reactions to environmental to the environment is a capacity exhibited by almost , events." He observed that hydranencephaIic children any organism with a central nervous system, and i~ ­ were able to "express pleasure by smiling and laugh­ ter, and aversion by fussing, arching of the back and cannot be definitely taken as a sign of consciousness. Furthermore, the behaviors of hydranencephalic chil­ :! crying." Furthermore, the children responded differ­ dren seem to lack the element of intentionality and entially to the voice of familiars, and showed prefer­ "many of the reported behaviors could be generated ence for certain situations and stimuli over others, unconsciously or reflexively." l : such as a particular familiar toy. More interestingly, : I some of these children demonstrated the capacity of J, :i- taking behavioral initiatives in the form of instru­ CONCLUSION mental behaviors, such as making noise by kicking ,Whether or not children born with hydranence­ trinkets hanging in a special frame constructed for phaly have consciousness is still controversial. How­ the purpose, or activating favorite toys by switches. ever, the body of evidence in favor of the presence of Merker concludes that hydranencephalic children consciousness in these patients seems to be more con­ "give proof of being not only awake, but of the kind of vincing than evidence and argu-ments against con­ responsiveness to their surroundings that qualifies sciousness in such children. as conscious by the criteria of ordinary neurological examination." Finally, it is noteworthy that the outstanding web­ site of the International Hydranencephaly Group According to Merker, another piece of evidence for ( provides comprehensive the existence of consciousness in hydranencephalic source of information about this disorder. The results children comes from the fact that these children are of an informal, nonscientific survey conducted by this subject to the seizures of absence epilepsy. Seizures of group revealed surprising findings that are contrary this type are characterized by lapses in consciousness to what is generally assumed by most neurologists and a lack of response toward external stimuli. In a regarding the presence of consciousness in hydranen­ typical episode of absence seizure, the patient sud­ cephalic children. When parents of such children denly becomes unresponsive in the midst of normal were asked "is your child aware of hislher surround­ activities. Ongoing activities may continue in the ings?," 74% of the surveyed parents answered "Yes," form of automatisms or they may arrest for the dura­ 2.46% answered "No," and 14.8% answered "Some­ tion of the seizure episode. At the end of such a sei­ times." When asked "is your child aware of objects?" zure, which may last no more than a few seconds, the "2t0.74% answered "Yes," 17.28% answered "No," and patient, who typically remains upright throughout, 38.27% answered "Sometimes." sometimes actively moving, resumes conscious activ­ The rarity of scientific observations similar to those ities where they were interrupted, has amnesia for , reported by parents could be partly due to the fact what transpired during the episode, and may have no that hydranencephalic children are extremely sensi­ knowledge that the episode took place at all. Merker tive to and easily disturbed by changes in environ­ argues that "episodes of absence in this form of epi­ ment and routine daily activities. In unusual and dis­ lepsy represent a basic affliction of consciousness," turbing situations, the children often fail to manifest and concludes "the fact that these children exhibit any cognitive functions that parents often report. such episodes would seem to be a weighty piece of When examined after medical stabilization has taken evidence r egarding their conscious status." place, and in the setting of the home environment • Merker s arguments for the presence of conscious­ ness in hydranencephalic children have not remained upon which these medically fragile children are cru­ cially dependent, th ey give proof of being conscious unchallenged. Behrendt (2007) believes that "signs of (Merker, 2007 ). pleasure or excitement exhibited by anencephalic chil­ dren are not necessarily in dicative of conscious expe­ rience" and they m ay be regarded as automatic be­ havioral reactions activated by appropriate stim uli. ACKNOWLEDG MENT In opposition to the notion that hydranencephalic I am indebted to Bjorn Merker for provid ing the children have consciousness, Morin (2007) argues pi ture of Niki an d receiving penllission from Nikis that behaviors exhibited b these patients do not mother. f,) Synapse I
  6. 6. 556 M . BESHKAR REFERENCES Morin A. 2007. Consciousness is more than wakefulness. Behav Brain Sci 30:99.Behrendt RP. 2007. the hypthalamo--tectoperiaqueductal system: Shewmon DA, Holmes GL, Byrne PA. 1999. Consciousness in Unconscious underpmnings of conscious behaviour. Behav Brain congenitally decorticate children: Developmental vegetative Sci 30:85--86. . state as self-fulfilling prophecy. Dev Med Child Neurol 41:364 ­Counter SA. 2007. Brainstem mediation of the stapedius muscle 374. reflex in hydranenccphaly. Acta Oto-Laryngol 127:498-504. Watkins S, Rees G. 2007. The human superior colliculus: NeitherMerker B. 2007. Consciousness without a cerebral cortex: A chal­ necessary, nor sufficient for consciousness? Behav Brain Sci lenge for neuroscience and medicine. Behav Brain Sci 30:p3-81. 30:107.":;vnnplP