Pernahkah anda mengalami kejadian dimana tangan atau bagian tubuh anda dapat bergerak sendiri tanpa mengikuti perintah kita, seakan-akan bagian tersebut punya kehendak sendiri? jika ya, kemungkinan anda juka terkena Alien Hand Syndrome ini.
Alien Hand Syndrome (AHS) atau disebut juga Dr Strangelove syndrome merupakan keadaan dimana bagian tubuh seseorang dapat bergerak sendiri tanpa diperintah seakan-akan bagian tubuh tersebut mempunyai pikiran dan kehendak sendiri.
Biasanya bagian tubuh yang dapat terkena sindrom ini adalah tangan, namun dalam beberapa kasus terdapat juga kaki.
Bayangkan jika tangan kalian tiba2 bergerak sendiri ketika kalian sedang tidur, berjalan, atau yang lainnya. Tangan bergerak sendiri seakan mempunyai pikiran dan kehendak lain selain dari otak. Ingin menulis tiba2 tangan melambai2, sedang jalan tiba2 tangan memegang2 yg lain, pastinya kalian akan merasa risih, aneh, dan ketakutan. Secara gampangnya seperti tangan doc.octopus di film spiderman yg dapat bergerak sendiri. misalnya ketika mengangkat tangan entah kemanan tangan kita bergerak
Karena begitu menakutkan dan membingungkan banyak orang yang membuat kesimpulan aneh2 seperti, tangan tersebut ada yg mengendalikan (memangnya di indonesia ada istilah susuk yang bisa mengendalikan orang), tangan mempunyai kesadaran/roh sendiri, kerasukan roh yang nyasar.
Penelusuran
"AHS adalah neurological disorder (kelainan neurologis) yang membuat korban merasa dia telah kehilangan kontrol dari salah satu tangannya.".
Berikut adalah teorinya
The common emerging factor in Alien Hand Syndrome is that the primary motor cortex controlling hand movement is isolated from premotor influences but remains generally intact in its ability to execute movements of the hand. A very recent fMRI study looking at the temporal sequence of activation of components of a cortical network associated with voluntary movement in normal individuals demonstrated "an anterior-to-posterior temporal gradient of activity from supplemental motor area through premotor and motor cortices to the posterior parietal cortex" (Kayser et al. 2009). Therefore, with normal voluntary movement, the emergent sense of agency appears to be associated with an orderly sequence of activation that develops initially in the anteromedial frontal cortex in the vicinity of the supplementary motor complex on the medial surface of the hemisphere prior to activation of the primary motor cortex. A recent fMRI study examining the difference in functional brain activation patterns associated with alien as compared to non-alien 'volitional' movement in a patient with alien hand syndrome found that alien movement involves isolated activation of the contralateral primary motor cortex, while non-alien movement involved the activation of primary motor cortex in concert with frontal and parietal association cortex presumably involved in a cortical network generating premotor influences on the primary motor cortex (Assal et al. 2007).
It is theorized that Alien Hand Syndrome results when disconnection occurs between different parts of the brain that are engaged in different aspects of the control of bodily movement. As a result, different regions of the brain are able to command bodily movements, but cannot generate a conscious feeling of self-control over these movements. As a result, the "sense of agency" that is normally associated with voluntary movement is impaired or lost. There is thus a dissociation between the process associated with the actual execution of the physical movements of the limb and the process that produces an internal sense of voluntary control over the movements, with this latter process thus normally creating the internal conscious sensation that the movements are being internally initiated, controlled and produced by an active self. Recent studies have examined the neural correlates of emergence of the sense of agency under normal circumstances (Spengler, et al. 2009). This appears to involve consistent congruence between what is being produced through efferent outflow to the musculature of the body, and what is being sensed as the presumed product in the periphery of this efferent command signal. In alien hand syndrome, the neural mechanisms involved in establishing that this congruence has occurred may be impaired. This may involve an abnormality in the brain mechanism that differentiates between "re-afference" (i.e., the return of kinesthetic sensation from the self-generated 'active' limb movement) and "ex-afference" (i.e., kinesthetic sensation generated from an externally-produced 'passive' limb movement in which an active self does not participate). This brain mechanism is proposed to involve the production of a parallel "efference copy" signal that is sent directly to the somatic sensory regions and is transformed into a "corollary discharge," an expected afferent signal from the periphery that would result from the performance driven by the issued efferent signal. The correlation of the corrollary discharge signal with the actual afferent signal returned from the periphery can then be used to determine if, in fact, the intended action occurred as expected. When the sensed result of the action is congruent with the predicted result, then the action can be labelled as self-generated and associated with an emergent sense of agency. If, however, the neural mechanisms involved in establishing this sensorimotor linkage associated with self-generated action are faulty, it would be expected that the sense of agency with action would not develop.
One theory posed to explain these phenomena proposes that the brain has separable neural "premotor" or "agency" systems for managing the process of transforming intentions into overt action. An anteromedial frontal premotor system is engaged in the process of directing exploratory actions based on "internal" drive by releasing or reducing inhibitory control over such actions. Damage to this system produces disinhibition and release of such actions which then occur autonomously. A posterolateral temporo-parieto-occipital premotor system has a similar inhibitory control over actions that withdraw from environmental stimuli as well as the ability to excite actions that are contingent upon and driven by external stimulation, as distinct from internal drive. These two hemispheric systems interact through mutual inhibition that maintains a balance between responding to and withdrawing from environmental stimuli in the behavior of the contralateral limbs (Denny-Brown, 1956, 1958, 1966). Together, these hemispheric agency systems form an integrated intrahemispheric agency system.
When the anteromedial frontal system is damaged, involuntary but purposive movements of an exploratory reach-and-grasp nature�what Denny-Brown (1956, 1966) referred to as a positive cortical tropism�are released in the contralateral limb. When the posterolateral parieto-occipital system is damaged, involuntary purposive movements of a release-and-retract nature, such as levitation and instinctive avoidance, are released. Furthermore, each intrahemispheric agency system has the capability of acting autonomously in its control over the contralateral limb although unitary integrative control of the two hands is maintained through interhemispheric communication between these systems via the projections traversing the corpus callosum at the cortical level and other interhemispheric commissures linking the two hemispheres at the subcortical level. Thus, human agency can be thought of as emerging through the linked and coordinated action of at least four major agency systems, two in each hemisphere.
The critical difference between the two hemispheres, however, is the direct connection between the agency system of the dominant hemisphere and the encoding system based primarily in the dominant hemisphere that links action production and its interpretation with language. Thus, the overarching unitary conscious agent that emerges in the intact brain is based primarily in the dominant hemisphere and is closely connected to the organization of language capacity. It is proposed that while action precedes linguistic capacity during development, a process ensues through the course of development through which linguistic constructs are linked to action elements in order to produce a language-based encoding of action-oriented knowledge. Through this process of basically "telling oneself a story" about how an act occurs, a language-based "action-capable" self is constructed through consistent correlations between intended actions and subsequent perceived outcomes.
When there is a major disconnection between the two hemispheres resulting from callosal injury, the language-linked dominant hemisphere agent which maintains its primary control over the dominant limb effectively loses its direct and linked control over the separate "agent" based in the nondominant hemisphere (and, thus, the nondominant limb), which had been previously responsive and "obedient" to the dominant conscious agent. The possibility of purposeful action occurring outside of the realm of influence of the conscious dominant agent, thus can occur and the basic assumption that both hands are controlled through and subject to the dominant agent is proven incorrect. The sense of agency that would normally arise from movement of the nondominant limb now no longer develops, or, at least, is no longer accessible to consciousness. A new explanatory "story" for understanding the nature of the inaccessible agent moving the nondominant limb is thus necessitated.
Under such circumstances, the two agents therefore can direct actions in the two limbs that are directed at opposing purposes although the dominant hand remains linked to the dominant consciously accessible agent and is thus viewed as continuing to be under "conscious control" and obedient to conscious will, while the nondominant hand is no longer "tied in" to the dominant agent and is thus identified by the conscious language-based dominant agent as having a separate and alien agency. This theory would explain the emergence of alien behavior in the nondominant limb and intermanual conflict between the two limbs in the presence of damage to the corpus callosum. The distinct anteromedial frontal and posterolateral temporo-parieto-occipital forms of the alien hand syndrome would be explained by selective injury to either the frontal or the posterior agency systems within a particular hemisphere, with the alien behavior developing in the limb contralateral to the damaged hemisphere.
maap terkadang saya malas menterjemahkan, hehehe>>>>>
kalo ga ngerti bisa di liat di penterjemah google....
http://en.wikipedia.org/wiki/Alien_hand_syndrome
http://rensenpelawi.blogspot.com/2010/02/alien-hand-syndrome-ahs.html
