Schizophrenic Noise and Schizophrenic Voices
Hear that voice? What, is there more than one? Is this real, or fake? How do you know? That is how schizophrenia works: auditory hallucinations, confusion, inability to tell what is real and what is not. Schizophrenia isn’t something a person can simply ignore. You can’t get rid of that voice, or even the voices on your own. But what causes this problem? That was the question researchers wanted to tackle.
Our brains are usually good at focusing on the information that we are trying to learn and filtering out the “noise” or thoughts that aren’t relevant [or as most of us know, our brains are horrible at multitasking]. However, memory impairment in schizophrenia may be related in part to a problem with this filtering process, which researchers studied.
“Our assumption was that understanding the impairments in the component processes of working memory – the ability to hold and manipulate information in the mind – among patients with schizophrenia could be fundamental to understanding not only cognitive function in the disorder, which is widespread and has debilitating consequences, but also the disorder itself,” Dr. Teal Eich, head researcher at Columbia University.
The team recruited patients with schizophrenia and [of course] a control group of healthy volunteers to complete an item recognition task in the laboratory while undergoing a functional magnetic resonance imaging [MRI] scan. In particular, they focused on analyzing potential activation differences in the ventro-lateral prefrontal cortex [or VLPFC for short, which for those of you who didn’t click the link is a region of the brain implicated in working memory].
The design of the task allowed for the assessment of the various components of working memory: 1) maintaining the memory itself, 2) inhibiting or ignoring irrelevant information, and 3) during memory retrieval, controlling the interference of irrelevant information.
So while only maintaining the memory, both groups showed a similar degree of activation in the VLPFC. During the inhibition phase, VLPFC activity is expected to decrease, which was indeed observed in the healthy group, but not in the schizophrenic patients, starting to get interesting, right? Finally, during interference control, schizophrenic patients performed worse and showed increased VLPFC activation compared to the healthy volunteers. Overall, the schizophrenic patients showed altered VLPFC functioning and significant impairments in their ability to control working memory.
“Our findings show that these patients have a specific deficit in inhibiting information in working memory, leading to impaired distinctions between relevant and irrelevant thoughts,” said Eich. “This result may provide valuable insights into the potential brain mechanisms underlying the reasons why these affected individuals are unable to control or put out of mind certain thoughts or ideas.”
This study adds to a growing literature suggesting that cognitive functions require both the activation of one set of regions in the brain and the inhibition of others. The failure to suppress activation may be just as disruptive to cortical functions as deficits in cortical activation.
Interestingly enough years ago, the pioneering scientist Patricia Goldman-Rakic and her colleagues showed that the inhibition of regional prefrontal cortical activity was dependent upon the integrity of the GABA [short for gamma-aminobutyric acid, an important inhibitory neurotransmitter] system in the brain, which is a chemical system with abnormalities associated with schizophrenia.
“We need to determine whether the cortical inhibitory deficits described in this study can be attributed to particular brain chemical signaling abnormalities,” said Dr. John Krystal, Editor of Biological Psychiatry. “If so, this type of study could be used to guide therapeutic strategies to enhance working memory function.”
You have to admit, neuroscience is fascinating. Understanding the differences between a “normal” functioning brain and people who suffer from different forms of mental illness will [in my opinion] help crack open the harder to determine functions in the brain. Things like how we think, feel, and who we are. I am not a religious person by any means [as always a personal preference], but if there was a soul, it’s locked away in the functioning of the brain.
And now a little more neuro fun!! [sorry in advance]
Teal S. Eich,, Derek Evan Nee,, Catherine Insel,, Chara Malapani,, & Edward E. Smith (2014). Neural Correlates of Impaired Cognitive Control over Working Memory in Schizophrenia Biological psychiatry, 76 (2) : 10.1016/j.biopsych.2013.09.032