Wednesday, June 20, 2018

Interesting result about binocular rivalry

Science Alert reported an interesting result from neuroscience. The title of the popular article was A New Brain Experiment Just Got Closer to The Origins of Consciousness. The original article Human single neuron activity precedes emergence of conscious perception is published in Nature.

The researchers in Tel Aviv University studied people suffering from epilepsy: the epilepsy as such is however not relevant for the research interests. During more than 20 sessions the volunteers stared at a pair of images. Each image was located in front of one eye. Because each eye saw only one image, the brains couldn't fuse the images into single picture. Instead, the brain choose one image to deal with at a time. This process is known as binocular rivalry. The article claims that this process allows to separate visual stimulation and conscious seeing for each other. I would however argue that the outcome of the experiment relates to binocular rivalry rather than generation of conscious percept itself.

The finding was that medial-frontal lobe becomes active two seconds before the subject sees the picture. A second zone becomes active second later in medial-temporal lobe ( that is 1 second before the conscious visual percept). These time scales are rather long as compared to time scale of 0.08-.1 seconds associated with sensory mental images - one might call this time scale a duration of sensory cronon.

As article explains, these experiments differ from the usual experiments studying the behavior of medio-temporal neurons in response to various modifications of the sensory input (flashing a different image to the other eye; backward masking, in which a briefly presented image is suppressed by the immediate presentation of a mask image; and the attentional blink, in which the second of two target stimuli appearing in close succession is often not perceived). Also these experiments study what happens at brain level as the visual percept changes but the change is now induced externally rather than internally as in binocular rivalry. The response of MTL neurons started about .2-.3 seconds after the external manipulation. There was no activation before the change.

If I understood correctly, the interpretation of the finding was based on computational paradigm. According to this interpretation it takes about 2 seconds to compute the new visual percept when the decision about new percept is made. One might however argue that this computation should take 2 seconds also in the case of externally induced change of percept. Actually the time for the emergence of the percept is .2-.3 seconds and there was no activation before the change.

In TGD framework this longer time scale would naturally correspond to a higher level in self hierarchy. In self hierarchy mental images correspond to sub-selves and self is sub-self of self at the higher level of the hierarchy. Each level is characterized by time scale and the higher the level in the hierarchy, the longer the time scale.

  1. Could a higher level self direct its attention to alternative percepts in bio-ocular rivalry in more or less random manner? Could this re-directing of attention be seen as a motor action at some level of self hierarchy? This is the case when I turn my gaze from one object of the perceptive field to another one.

  2. In TGD picture motor based on zero energy ontology (ZEO) motor actions are identified as sensory percepts in opposite time direction: a signal is sent to geometric past and initiates neural processing leading to the motor action. This explains Libet's finding that motor action is preceded by a neural activity beginning A fraction of second before the conscious decision about motor action. Could the situation be the same now except that the time scale would be now longer? The longer time scale would suggest that the decision maker is not "me" characterized by a fraction of second time scale but some higher level in the hierarchy of selves associated with my biological and magnetic body.

For a summary of earlier postings see Latest progress in TGD.

Articles and other material related to TGD.

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