The title of this blog is not meant to imply that the other days haven’t been good – they have been superb! They just weren’t quite what I came here for. Today, we started to get into the good stuff about cognition, behaviour, memory and affect – just started…
The morning was given over to a couple of field trips to see the ERP lab (more imaging), the TMS lab (stimulating the brain with magnetic current) and the tDCS lab (stimulating the brain with direct current). None of them were dangerous and no one got their head examined. Overall, my big take-away from the morning is that when the brain is stimulated in specific areas by certain methods, it can provide causal, rather than correlational, evidence of the function of a brain area.
Cautions: sometimes, the area of the brain being stimulated isn’t precise, and sometimes it’s not clear (except through fMRI) which part of the brain is actually being stimulated. Sometimes, you think it’s one area, but another related area can also light up. Also, especially with electrical signals, they can move in unanticipated ways due to the different tissues, membranes and bones involved. Also, these methods typically only stimulate the cortical areas of the brain, near the skull. For deep brain stimulation, you need to do surgery. We didn’t see that.
Oh – and while I’m thinking of it – the reason most links go to Wikipedia is just for convenience. Wikipedia is often a good place to start if you are looking for basics on these technologies. If you want details, check out some of the links from the Center for Neuroscience & Society at the University of Pennsylvania.
Now – the afternoon….
In the afternoon, we started to get into an introduction to cognitive neuroscience. We talked about perception and attention (as the “inputs”), memory (as the “storage” and “manipulation”) and behaviour (as the “output”). So this is really what I was most interested in. Our day ran a bit late, but really I would have stayed an extra two hours to hear more about this topic!
I took copious notes, so if you have any questions, please post them. To keep this blog relatively brief, I’ll share some of my highlights and insights.
We have learned a lot about brain functioning in these areas from patients – people who have lesions or traumas to specific brain areas, and then learning from their behaviour about those parts of the brain. Examples might include Phineas Gage, prosopagnosiacs, and Clive Wearing. All powerful stories, which have, as a beneficial side effect, contributed to our understanding of the role various parts of the brain play in cognition.
We talked at great length about the different types of memory: episodic, semantic, declarative, non-declarative, and so on. A large taxonomy of memory. And we learned about the role of the hippocampus, which is believed to be responsible for the consolidation of memory – turning short-term memories into long-term memories distributed in the cortex. We also learned that the amygdala, sitting next to the hippocampus, could be the reason why memories associated with strong (usually negative) emotions are more easily imprinted and remembered. There is a lot of research behind these ideas.
I’m also struck by the notion that, if you wish to learn complex things and retain the knowledge, you can’t learn it in one trial. You need several exposures over time, perhaps each exposure presenting different information about the complex thing, to ensure that the learning gets distributed. Otherwise, it goes to a short-term memory and then when you’re done with it, the information simply disappears and leaves no trace. High school algebra, anyone?
Different learning also takes place in different parts of the brain. Procedural (implicit) learning seems dependant on the basal ganglia, and you can do this sort of learning without a hippocampus. So learning motor skills or habits is in a different part of the brain than episodic learning.
Finally, we wrapped up the day with learning about Executive Function. Our day was running late, and I really wish we’d had more time to discuss and learn about EF. Essentially, it lives in the pre-frontal cortex (PFC) and is, as you might imagine, more active when you are trying to do two different simple things at once (like watching for a visual signal AND listening for an auditory signal, with two different buttons to push depending on which one you detect first…). Again, much of the data on this functioning comes from patients (aforementioned Phineas Gage) and when the EF is taxed or weakened, the system is “adrift”, steered by the environment, habit or the momentum of a previous task.
This is probably why grocery stores put candy at the check-out aisles – your EF is weakened and so you just seize on to environmental cues, and you just pick up that chocolate because it’s right there!
I asked if we can willfully improve our EF without drugs or external brain stimulation, thinking of Baumeister’s concept that willpower is a muscle and you can exercise it to make it stronger. I believe there is anecdotal and self-report evidence for this, and I was curious if fMRIs show any difference. Apparently, the answer is “yes”. Early attempts to “train the brain” with various tools and software packages showed that it only worked for the very specific tasks that the game asked you to perform, but now it seems that there are other possibilities that allow you to generalize EF more effectively across functions. I didn’t get the chance to talk about specifics, but it seems to work by reducing the energy requirement of the brain to exercise EF – it makes your brain more efficient when using EF. As we know, the brain likes to be as energy efficient as possible, and the EF function is a heavy drain on the system, and breaks down easily.
Most interestingly, our instructor (Martha Farah) is keenly interested in this field of study, so guess whose name I’m going to be following in my new google alerts?
Tomorrow is Saturday and no rest for the learning! We’ll be into social-affective neuroscience (part 1). Stay tuned!
And just for fun, and to help with EF and willpower, here’s the famous marshmallow experiment for adults: