Posts Tagged ‘Francis Crick’

Consciousness Enters the Lab

April 2, 2016

Consciousness Enters the Lab is the First chapter discussed in “Consciousness and the Brain”  Deciphering How the Brain Codes our Thoughts,” which is an outstanding book by the French neuroscientist Stanislas Dehaene who is the Chair of Experimental Psychology at the College of France.  As was discussed in the previous post, although consciousness is an extremely important concept, it has been difficult to bring it into the lab and conduct meaningful experiments regarding it.  This first chapter discusses the new methodology.

This first chapter focuses on the issue of conscious access, the question being why some of our sensations turn into concept perceptions, while others remain unconscious.  The methodology builds upon one of the oldest in psychophysics, the identification of thresholds.  This involved presenting a stimulus and asking the respondent if it can be perceived.  Brain imaging is then added to this technology to see what parts of the brain are responding.  The signature of consciousness is found in those parts of the brain that respond when the individual indicates the presence of the stimulus.  Parts of the brain will also be responding when the individual does not indicate the presence of the stimulus.  These are the parts of the brain that, although they are activated, do not result in conscious perception.  Remember that most of the brain’s activity is unconscious.  Conscious activity represents only a very small percentage of the brain’s activity, but the parts of the brain that do respond with the individual’s indication that the stimulus is perceived, are those parts that are conscious.  This procedure was invented/discovered  by the late Nobel Prize winner Francis Crick and the neurobiologist Christof Koch.

The procedure is not as simple as it appears.  The identification of a reliable threshold requires multiple trials.  This procedure is also done with multiple participants.  So there are many brain images over many participants.  But when done properly, reliable signatures of conscious activity are identified for the relevant parts of the brain.  Thus, consciousness becomes  a meaningful measure for scientific study.

Scientists have often referred to consciousness as “wakefulness” or “vigilance..”  But wakefulness refers primarily to the sleep-wake cycle. And vigilance refers to the level of excitement in the cortical and thalamic networks that support conscious states.  However, both concepts differ sharply from conscious access.  Wakefulness, vigilance, and attention are enabling conditions for conscious access.  Selective attention and conscious access are also distinct processes.  In many cases attention operates sub rosa, covertly amplifying or squashing incoming information even though the final outcome never makes it into our awareness.

Of course, scientists are creative and there are variants on the above technique.  But the primary point has been made.  We are remain unaware of the vast majority of the activity in the brain.  However, signatures can be developed to identify parts of the brain that reflect conscious activity.

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A Key Component Generating Conscious Experience?

October 29, 2014

The November/December 2014 issue of Scientific American Mind included an article by Christof Koch, who is a former collaborator with Francis Crick, who with James Watson won the Nobel Prize for discovering the structure and the function of DNA. The title of the article is “A Brain Structure Looking for a Function.” The brain structure in question is the claustrum. The claustrum is a thin, irregular sheet of cells, tucked below the neocortex, which is the gray matter that allows us to see, hear, reason, think, and remember. It is surrounded on all sides by white matter, the tracts, or wire bundles, that interconnect cortical regions with one another and with other brain regions. There are two claustra one for each side of the brain. They lie below the general region of the insular cortex, underneath the temples, just above the ears. They have a long, thin wisp of a shape that can be easily overlooked when inspecting the topography of the brain region.

Advanced brain-imaging techniques have revealed white matter fibers coursing to and from the two claustra that it is a neural Grand Central Station. Almost every region of the cortex sends fibers to the claustra. These connections are reciprocated by other fibers that extend back from the claustra to the originating cortical regions. Although each claustrum receives inputs from both cortical hemispheres, but only project back to the overlying cortex on the same side.

Crick looked at these facts and believed that a reliable guide to understanding function, is to study structure. And he, working with Koch formulated the idea that the claustra are a key component of the networks generating conscious experience. This work turned out to be Crick’s Swan Song to science as he was suffering from end-stage colon cancer. He finished his paper with Koch before passing away,

“What is the Function of the Claustrum?, Philosophical Transactions of the Royal Society B, Vol. 360, No.1458, pages 1271-1279.

Additional research supporting this contention of Crick and Koch is cited in the Koch piece in Scientific American Mind. Nevertheless it is always fascinating to speculate about conscious. It is the only product of the brain with which we have direct experience. Yet the brain is raging with activity 24 hours a day. There are many reasons to believe that we can use our conscious experience to improve our focus and ability to attend. We can also use it to control our emotions and it lets us take a third person look at our own interactions with other. Fundamentally, meditation and mindfulness is a matter of learning to control our conscious experience to advantage.

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