People in a vegetative state, usually as a result of brain trauma or anoxia (lack of oxygen) by definition have no signs of conscious awareness or activity. The definition, therefore, is based largely on the absence of evidence for consciousness.
Of course, arguments based upon the absence of evidence are only as compelling as the degree to which evidence has been properly searched for. In recent years technology has advanced to the point that our ability to detect the possible subtle signs of consciousness in those presumed to be vegetative has increased – mainly through functional MRI scans (fMRI) and electroencephalograms (EEGs).
There has been a steady stream of studies demonstrating that a small minority of patients thought to be vegetative actually display some signs of minimal consciousness. The latest such study was recently published in Neuroimage: Clinical by a research team from the University of Cambridge.
But let’s back up a bit first. Even prior to evaluating vegetative patients with fMRI and advanced EEG techniques, several studies showed that a detailed neurological exam specifically designed to detect the most subtle clinical signs of consciousness could find such signs in some patients who were diagnosed as being vegetative by more standard neurological exam. According to one study as many as 41% of patients diagnosed as vegetative were really minimally conscious, meaning they had subtle signs of consciousness, but still cannot wake up, converse, or act purposefully. (more…)
Sally Satel and Scott Lilienfeld have written a new book, Brainwashed: The Seductive Appeal of Mindless Neuroscience. Its purpose is not to critique neuroscience, but to expose and protest its mindless oversimplification, interpretive license, and premature application in the legal, commercial, clinical, and philosophical domains.
The brain is a wondrous thing: “…the three pound universe between our ears has more connections than there are stars in the Milky Way.” Trying to understand how it works and how it generates conscious awareness and subjective feelings is a daunting task. Neuroimaging is one of the tools we are using to study it. Unfortunately, people get so enthusiastic about its possibilities that they are constantly tempted to read more into the images than is really there. This has given rise to a new phrenology that interprets our mental characteristics with pretty colored pictures. We are easily impressed by pictures; after all, a picture is worth a thousand words.
Brain imaging can’t show us what is going on in the mind of the person. It shows areas that have increased oxygen consumption. A spot lights up when a person thinks or acts, but that doesn’t tell us much. Single blobs that light up in the brain have been interpreted as centers for things like love, rewards, hate, and belief in God. This is sometimes referred to as “blobology.” They found an area in one person that lit up when he thought about an actress he loved. That area was thought to be a “reward” center. But it also lit up when he thought of Ahmadinejad! So they did some fancy footwork and rationalized that he believed that the Jewish people would endure and therefore he derived pleasure from the idea that Ahmadinejad would fail. That’s pretty far-fetched. Occam’s razor would suggest that maybe the area that lit up was reacting not to pleasure, but to something else. People tend to read what they want to see into ambiguous patterns like a Rorschach test. Mental functions are rarely limited to a single spot in the brain; multiple areas are involved and interconnected. Researchers are increasingly moving away from blobology and towards pattern analysis where they look at the patterns of activation across the entire brain. (more…)