In a recent well-publicised New England Journal of Medicine study, researchers have found an has been the association of between expected brain activity with and answers to questions about familiar topics in a person with a previously clinically recognised vegetative state. There is coverage of the study here which includes a video showing the location of brain activity in the visualisation tasks in a demonstration. The original paper is here and the supplementary paper is here. This was a continuation of previous research in this area a few years ago. The researchers used fMRI with a 3T scanner in two European sites. The controls and the subjects were asked to visualise themselves hitting a tennis ball or walking from room to room in their home while visualising the scenery.
These two tasks activated the supplementary motor area (SMA) (motor task) and parahippocampal gyrus (PHG) (spatial task) respectively. The researchers then asked all subjects to associate the motor task with yes and the navigation task with no. They were careful to ensure that the subjects attended to these tasks with a period of sustained attention so that the signal could be distinguished from that associated with more automatic responses. This was done in order to increase the likelihood that the activity represented ‘conscious’ activity. The tasks were repeated on 5 occasions to increase the reliability of the data after averaging the signals.
They then presented subjects with autobiographical questions. I wasn’t clear on whether the questions varied from one subject to another. They were then asked to think the correct response – a yes or a no by means of the associated imagery. The researchers averaged the activity for the imagery tasks. They averaged the activity for the responses to questions. They identified the ‘centre’ of the activity for both tasks and calculated the distance of the centres of activity from each other to produce a ‘similarity’ score. The ability of a person to produce activity in the SMA or PHG in response to the researcher’s instructions was inferred as evidence of the will (although perhaps an interruption of auditory or semantic processing may interfere with task responses also). Of 54 patients in the study with a clinically recognised vegetative state, in 5 of those people activity in the appropriate areas were associated with the researchers’ instructions on the imagery tasks. However when it came to the autobiographical questions, only 1 subject produced activity associated with the correct responses. In this subject the expected activity for correct responses was identified in 4 out of 5 of the autobiographical questions.
What was interesting here was that as well as averaging group activity and comparing groups, the researchers focused on the individual results. Perhaps this was necessary as there was only one subject with the anticipated evidence of ability to respond to questions. I wasn’t clear on what the researchers’ thoughts on the ‘incorrect’ response was and which method was used for controlling for multiple comparisons (this time it’s a slightly different type of multiple comparison to that discussed in a previous paper reviewed here) as the tasks were administered to 54 subjects with the above results. It will be interesting to see further results in this area and if this approach proves successful then there may be other conditions which it might be applicable to where there are similar difficulties with communication.
A recent relatively small study in the Archives of General Psychiatry looked at people with schizophrenia (n=8) and compared them with controls (n=8). They used structural imaging to compare the hippocampal volume after a program of aerobic exercise. There was found to be 12% increase in hippocampal volume in the people with schizophrenia and a 16% increase in the control group adding to the evidence base for the benefits of exercise in both health and illness (see also the book reviewed in this post).
Electroretinography has been used to investigate healthy people with a family history of schizophrenia or bipolar disorder and the researchers have found preliminary evidence of a reduction in the responsiveness of the rods in the retina. They compared 29 people with a family history of either Bipolar Disorder or Schizophrenia with 29 healthy controls without a family history of these disorders. They found a significant difference on one of the amplitude measures (23%)(p<0.0001). The researchers interpreted this as suggesting a possible genetic basis for an alteration in the early stages of sensory processing. However it will be interesting to see if these findings are replicated in larger studies and if so then it will complement other lines of evidence showing a relationship between altered perceptual (rather than sensory) processing in the cortex and psychopathology.
Researcher Kausak Si teamed up with Eric Kandel to investigate the role of a protein called CPEB in slugs. The CPEB is located in neuronal synapses. When the researchers targetted antibodies to CPEB they interfered with the ability to form new memories. They found that CPEB was similar to prions found in Yeast and have speculated that self-replication might play a role in memory formation (although they didn’t have evidence from this study for that particular hypothesis). Prions have been identified in a number of pathological conditions including Creutzfeld-Jacob disease. rather than in health.
MindHacks has another spike activity including a link to an article about the recent study showing evidence of grid cells in humans.
The Frontier Psychiatrist has a very interesting interview with psychiatrist Dr Iain McGilchrist
Music has a strong relationship to language and recent research covered here highlights the close relationship between the two. This relationship has a number of possible implications in a wide number of areas which involve language. A recent study (from a few months back) looked at music appreciation in cotton-top tamarins (a form of New World monkey) and the researchers found that they were responsive to music written specifically for them but not to human music. The music can be heard at the link above and was based on the tamarin’s own calls and other vocalisations. For anyone curious about what cotton-top tamarins look like, I’ve made two short videos (here and here).
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