Their blind hemifield (Bittar et al).In contrast, following stimulation from the intact hemifield, hemispherectomized individuals activate precisely the same brain places within the contralateral hemisphere as normal sighted controls.Recent DTI studies revealed that the information and facts originating within the blind hemifield is routed by means of the intercollicular commissure for the contralateral superior colliculus, then towards the pulvinar to attain the visual cortex of your remaining hemisphere (Leh et al ,).These results are supported by neuroanatomical data displaying a outstanding preservation of both superior colliculi in hemispherectomized monkeys (Th ret et al).The remaining hemisphere thus seems to play a role inside the implicit processing of visual details presented inside the blind hemifield.When the major visual cortex is vital for visual consciousness, how can we explain that blindsight continues to be present in hemispherectomized patientsConsCious versus unConsCious perCeptsrecurrent activation processing doesn’t take place, leaving the technique in a subliminal state.This may well explain why awake PVS patients may perhaps show basic visual functions for example eye movements andor visual fixation without the need of showing signs of visual consciousness (Owen et al Bruno et al).subjeCtive experience (quAliA) Connected with ACtivAtion on the visuAl CortexAs it has become clear from the research described above, the occipital cortex in congenitally blind individuals is recruited by a wide selection of distinct kinds of sensory stimuli and cognitive tasks.It can be generally accepted that cortical activity in a specific area produces a subjective sensation inside precisely the same domain.As a result, electrical stimulation experiments showed that stimulation in the somatosensory cortex (SI) induces tactile sensations referred to a specific physique location.These stimulation research Drosophilin B custom synthesis further showed that the physique is somatotopically mapped as inputs from neighboring body components are encoded in adjacent components within SI (Penfield and Boldrey,).TMS is usually a strategy that enables to stimulate the cortex within a noninvasive manner, either together with the aim to interfere with brain activity within a specific brain location or to assess cortical excitability by evoking subjective sensations such as phosphenes or overt motor responses (Cowey and Walsh,).As an example, the phosphene threshold is decreased after a brief period of blindfolding, indicating an increase in the excitability in the visual cortex (Boroojerdi et al ).In view of the earlier described crossmodal responses within the occipital cortex with the blind, the question arises which style of sensations will be induced when applying TMS more than the occipital cortex in these subjects.Studies in rewired ferrets look to suggest that activation in the auditory cortex might be perceived as visual and not as auditory (von Melchner et al).We addressed this question in a series of research (Kupers et al Ptito et al a).Within a first study, we exploited a tactiletovision sensory substitution model to examine the subjective character of encounter related with all the activation of occipital cortex ahead of and just after the establishment of crossmodal plasticity (Kupers et al).A lot more particularly, we wanted to test whether stimulation from the occipital cortex induces subjective sensations connected with all the new (tactile) input.Thereto, we applied TMS more than the occipital cortex before and after training with the tongue display unit (TDU) within a group of congenitally blind and blindfolded sighted handle subjects.The TDU is a PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21542743 sensory s.
