Author’s Note: Article originally published in BrainWorld Magazine.
Author’s Note: Article originally published in BrainWorld Magazine.
Yes, it’s that time of year again, when we make resolutions and promptly fail at them.
But it’ll be different this year, you tell yourself. I’ll actually keep my resolutions. Yes, yes, of course you will.
Since I, like most everyone else, have a positive bias towards myself, I have made the resolution to maintain this blog appropriately. It’s hard though. I’m teaching myself programming, getting my associate’s (then my bachelor’s) degree in computer science, while also trying to figure out how I’m going to go back to grad school, and feed myself while in school. I’m also working full-time, and I’m starting a neuroscience educational online business with a few other people. Oh, and I’m working on a neuroscience children’s book and on a fantasy novel. I want both of them published by the end of the year, or at least in the process of being published.
Regardless, I want to maintain this blog. But I want to make changes. I am going to make it more cognitive and behavioral neuroscience based, since that’s what I plan on going to grad school for. I have a list of grad schools and their cog neuro programs. So hopefully this October I will begin applying. And hopefully by March 2016, I will know what schools I have been accepted into, if any. and then by August 2016, I will hopefully be starting my graduate school journey! I’ll be 26, though, so old. Le sigh.
At any rate, the goals for this blog will be to choose a new paper every week related to cog/behavioral and some computational neuroscience. I plan on summarizing the paper in layman’s terms for readers.
I also plan on choosing some new technique in neuroscience research. Technique Thursday.
I will also have some sort of historical neuro paper discussed, something that marked a turning point in neuro history, or was some sort of research landmark.
I also want to review a new neuro or psych related book every month. That means I’ll be reading A LOT. But that just means I’ll be learning A LOT. Yay learning!
I also want to discuss crazy neuro experiments, including any sort of ethics as to why the experiment should not and could not be done today. Manic Monday.
So there you have it. A breakdown of the new year of 2015. I will begin on Monday January 5, 2015!
Manic Monday: Crazy experiments in neuro and the modern-day ethics behind them
Technique Thursday: A cool neuro research technique; what it is, what it’s used for, a landmark study done with that technique
Findings Friday: A new study or discovery in cog/behavioral/computational neuro
Séance Sunday; Historical papers (séance because we’re talking to the dead scientists who did the experiment; well, I assume not all will be dead, but still, some of them at least)
And every month, a new book review. Or hopefully every month. Maybe every two months, depending on how involved the book is.
And I plan on having guests. Maybe. Hopefully. Fingers crossed.
Impostors, impostors everywhere. Or are they?
David was involved in a bad car accident. He sustained head injuries when he landed head-first on the ground. Seemingly, though, he was fine, retaining the capacity to talk and walk. But there was a problem. Whenever David saw his mother, he would say that she looks like my mother, but really, she is not my mother. She is another woman who is, for some reason, pretending to be my mother. She is an impostor.
In Capgras delusion, the sufferer will look at another person, and claim that that other person is an exact double—an impostor. Never mind the fact that this “impostor” has mannerisms, characteristics, the same voice, as the “original” person. To a Capgras delusion sufferer, these facts do not matter.
David also thought his father was an impostor. Sometimes, he would tell his father, “You know, I think you’d like to meet this guy. He’s so much like you. But he drives better; he doesn’t go so fast.” David would know that his father was his father, but he also believed that there was another man, just like his father. This other man was his father’s impostor.
David would say that his father’s “impostor” looked exactly like his father, but is adamant that it is not his father. You cannot convince David otherwise. When questioned about when he looked at the person who looked like his father, David said, “There is a difference in the fact that I know that the person happens not to be my father…I don’t expect things from that person as I would expect from my parents.”
Capgras delusion isn’t limited to faces, to people, but to animals as well. Delusions may even include objects.
For example, David was sure that the house he lived in was just an imitation. One day, he told his mother that he wanted to go to his house, to David’s house. So his mother took him outside, went around the building, back through the elevator (it was an apartment, not technically a house), and took him back into the apartment room. His mother told him, “This is your house.” David was placated. He looked around and agreed that the room, where he had been in before his mother took him around the building, was his actual house.
Things could get stranger. The Capgras delusion sufferer can think of their own selves as an impostor of their “real” self. The delusion isn’t confined to things beyond the person.
The etiology of Caprgras delusion is not known, but there are still some ideas. In the temporal lobes of our brains, there is an area dedicated to processing faces. It is possible that Capgras delusion sufferers have some sort of temporal lobe damage. Not only that, but some visual pathways project into the temporal lobe. When a face is seen, the visual pathway is activated, which then activates another pathway that projects to the amygdala, the center for emotional processing, including fear and aggression. When David saw his father, he was sure it was an impostor. But when he spoke to his father on the phone, David no longer thought of his father as an impostor; the man was now his actual father. This goes along with the idea that the delusion is associated with some sort of damage to the visual center, and its projections to the emotional centers of the brain.
There is laboratory evidence that in a Capgras delusion patient, the emotional reaction we get from seeing another person is missing when they look at someone.
Skin conductance measures are taken to determine a person’s emotional response to a stimuli. Skin conductance is what is behind the so-called lie-detector tests. When you exhibit an emotional response say, to an image or a sound, your skin momentarily becomes a better conductor of electricity. The skin conductance sensor (SCS) is also known as galvanic skin response to indicate this phenomenon.
When you are shown a picture of a loved one, your skin conductance changes, and it can be recorded. This is because a familiar face elicits an emotional response from you: it is physiologically arousing (arousal here indicating any sort of activation, not necessarily sexual arousal.)
But put a Capgras delusion sufferer in the same situation, and guess what? They don’t exhibit a physiological response. Their skin conductance doesn’t change, even if they are shown a picture of their mother, their spouse, a sibling, a best friend. There is no emotional significance.
Mirror, mirror on the wall, who I see is not me at all.
When you look into a mirror, who do you see? Yourself?
Not if you have Mirrored-self misidentification, a delusional belief that your reflection in a mirror belongs to a stranger’s. The stranger just happens to look like you.
The disorder might be because of mirror agnosia, an inability to properly interact with a mirror. There might also be a deficit in facial reading and identification involved.
What is really interesting is that this delusion can be induced in a laboratory via hypnosis. One study took participants and hypnotized them, urging them that when they looked into a mirror, they would either see a stranger’s reflection or not be able to recognize the person. Half of the participants received the suggestion when hypnotized, and the other half received it when fully awake. Needless to say, those hypnotized with the suggestions suffered from the mirror delusion later.
One patient, TH, was known to also have mirror agnosia. That is, he didn’t understand how mirrors worked. For example, when he looked into a mirror and an object was held up behind him and reflected in the mirror, TH was asked to touch the object.
Guess what he did?
He put his hand to the mirror, and then put his hand behind the mirror, in an attempt to ‘touch the object’. He never attempted to reach behind his shoulder.
TH said his reflection was a “dead ringer” for himself. He even attempted to speak to the reflection, as if it were another person. Since the reflection never replied, TH assumed the reflection had lost his voice.
TH was then asked about the reflection’s personality. He said that the person didn’t give him any reason to be weary of him. And when asked where the reflection loved, TH said he lived in an apartment next to his own apartment.
Another patient, FE, suffered from Mirrored-self misidentification, but not mirror agnosia. He did however have facial processing deficits. When he looked into a mirror, his perception of his face was no different from his memory of his face that he was unable to belief that the reflection was his.
Interestingly, both TH and FE were found to have developed dementia. It seems that Mirrored-self misidentification is found in a number of dementia cases. A study indicated that a number of dementia cases were unable to fulfill the reach-over-the-shoulder task assigned to patient TH. However, not all Mirrored-self misidentification patients are dementia cases. Schizophrenia and stroke patients can also exhibit the delusion. But even these patients are not most of the delusion cases.
In the end, it was found that to TH, a mirror was just a window, and since anyone you see through a window is not yourself and is apart from yourself. The person is a part of the world, separate from you. Therefore, the reflection is not you; it just cannot be.
The corpus callosum is the bundle of never fibers that connect the two hemispheres of the brain. It’s the largest single structure in the brain, with some two hundred million fibers. As a last resort for epilepsy, this bundle can be cut in a procedure known as a callostomy. When this happens, a split-brain patient can occur.
What is interesting is that these split-brain patients do not appear outwardly abnormal. There is not any indication that they have a severed corpus callosum if you saw them walking down the aisle at your local supermarket. They do not make weird facial expressions or odd gestures, they do not walk or speak ‘funny.’ They seem just like you or me.
But the evidence for their disorder abounds in the lab.
When the corpus callosum is severed, the two hemispheres of the brain, the left hemisphere (LH) and the right hemisphere (RH), cannot communicate well (this is why cutting the corpus callosum works in epileptic patients: the electrical discharges remain confined to one hemisphere instead of spreading between the two). Language is usually localized in the LH, while abstract thinking is the domain of the RH. (The whole thing about left brain is logic and right brain is creativity is true, but not really. The hemispheres are important for certain tasks, but overall, the whole left-brain-right-brain thing is overgeneralized and exaggerated. Our brains are far more complex than that).
One experiment involved a patient named VP. VP sat in front of a screen that played movies to the RH. The movie was a violent one, with people getting pushed off balconies and firebombed. But after watching the movie, VP could only remember this much: “a white flash, perhaps a few trees but definitely no people.” But when asked about feelings or emotions, VP said this: “I don’t really know why, but I’m kind of scared. I feel jumpy. I think maybe I don’t like this room, or maybe it’s you, you’re getting me nervous.”
The RH experienced the emotions (nervousness, fear) and processed them, but with the severed corpus callosum hindering interhemispheric communication, the left hemisphere was unable to figure out the source of the emotion.
Another experimenter flashed laugh to the RH of a split-brain patient. The patient laughed. Remember, language is a LH task. When the experimenter asked the patient what they were laughing at, the patient responded, “Oh, you guys are really something.” The LH gave a verbal explanation for the laughing. In this case, the LH was trying to interpret the laughing and trying to understand its cause, even though it actually did not. The LH, as the experimenter explained, is aware of what the person is doing and tries to interpret from there, rather than understanding the actual cause for the behavior.
Split-brain patient ‘Joe’ was tested in an experiment about visual fields. In the experiment, Joe sits in front of a computer. The computer screen has a dot in the center of it where Joe is told to stare at. When Joe focused on this central dot, everything on the right side of the screen is processed in his LH (remember, the right side of the brain controls the left side of the body, and vice versa). Since the LH is dominant for language, Joe should be able to read or say what he sees. The rest of the screen is a blank white screen. In intervals, words and images are flashed on the right side of the screen (i.e. to the right of the central dot). When Joe sees a word or an image, he reads or says it aloud to the experimenter.
For example, one of the words was tree. Joe would read car aloud. One of the images was a bundle of purple grapes. Joe told the experimenter grapes.
What’s interesting is when a word, for example, pan, is flashed to the left of the dot, Joe isn’t able to say what it is. He just says that he didn’t see anything. What gets even more interesting, though, is when he is told to draw what he says he didn’t see. He does so, drawing with his left hand, which is controlled by his RH. The result is a drawing of a pan. Then when Joe is asked what it is that he drew, he says pan.
What happened is that when the words or images were flashed to the left side of the dot, the information would go to his RH, which is not involved in language. Therefore, Joe was not able to say what an object was, because his RH from disconnected from the language-oriented LH.
Don’t worry, it gets stranger.
At one point, a picture of a saw was presented on the left side of the screen, and a hammer was shown on the right side if the computer screen. Joe says he saw a hammer.
He never says anything about the saw. But when the experimenter tells Joe to close his eyes and draw with his left hand, guess what he draws? The saw. And guess what he saws when he is asked what it is that he drew? That’s right, a saw.
Experimenter: “What did you see?”
Experimenter: “What did you draw?”
Experimenter. “What did you do that for?”
Joe: “I don’t know.”
The effects are not just seen with patients staring at computer screens. Take a blindfolded non-split-brain individual and put a ball in their left hand. Their RH knows what the ball is, and this information goes to the LH, which is able to verbalize and say that a ball in is the person’s hand. But do the same thing with a split-brain patient, and they will not be able to say what the object in their hand is. They know what it is, what to do with it, can draw it, but they cannot give you its name.
Lingual description is out of their reach.
In imaging, there are certain methodologies, like the cognitive subtraction methodology. In this method, activity in a control task in subtracted from activity in an experimental task. So for example, take a word task. A simple model of written word recognition is used. In a famous experiment, the Peterson et al. (1988) experiment, they wanted to identify brain regions involved with 1) recognizing written words, 2) saying the words, and 3_ retrieving meaning of the words. The researchers used cognitive subtraction to tease out all the things they were testing.
So, to work out which regions are involved with recognizing written words, the researchers compared brain activity while subjects passively viewed words versus passively viewing a cross (+). The idea behind this was that the same brain regions, the same visual processing is involved in passively viewing things. But, the experimental task involved word recognition visually, and therefore, subtraction could be used to tease out the brain regions involved.
To work out which regions are involved in spoken words, the researchers compared the viewing of written words with reading a word aloud. In this task, both experimental and baseline involved visual processing of the word, and word recognition, and therefore subtracting should cancel out things, but the experimental task would be able to be analyzed afterwards.
To work out which regions are involved in retrieving the meaning of written words, the researchers compared a verb-generation task with reading aloud.
What the researchers found was that the left lateral hemisphere is involved in these processes. Recognizing written words activated bilateral sites in the visual cortex. Producing speech activates the sensorimotor cortex bilaterally. Verb generations activates the left inferior frontal gyrus.
Of course, there are some issues with cognitive subtraction. Can you think of any?
For example, let’s consider the subtraction behind determining which brain regions are associate with written word recognition. The assumptions was that both tasks involve visual processing but the experimental task involves the component of word recognition. Therefore, there is the assumptions that adding an extra component does not affect the operation of earlier ones in the sequence. This is referred to the as the assumption of pure insertion, or pure deletion. It could be that the amount, type, etc of visual processing that deals with written words is NOT the same as for the visual processing that deals with non-linguistic visuals. The added extra component in the tasks has the potential to change the operation of other components in the task. That is, there could be interactions (the effect of one variable upon another) that make the imaging data ambiguous.