The gateway hypothesis

Some notes on Burgess et al’s review of BA10…

There’s a bit of the brain called the rostral prefrontal cortex (also known as Brodmann Area 10; BA10). It’s interesting as it’s big; it’s not as big in other animals (and thus might be one of the Special Bits of The Brain That Make Humans Unique); and it’s last to be myelinated during development.

BA10 shows BOLD activation (i.e., between conditions, averaging across participants, post-big-Guassian-kernel smoothing, there’s a signficant difference in BOLD activiation) for a range of different tasks: verbal memory, nonverbal memory, semantic memory, motor learning, rule learning, shock/tone conditioning… BA10 was once thought to be responsible for episodic memory, but it’s not activated only by episodic memory tasks.

Theories of what it’s doing: episodic memory; metacognition (e.g., relflection which rises to consciousness, manipulating the outputs from cognitive processes); action selection; some think that the mrPFC is involved in processing when you’re not actively thinking about something.

Lesion data for this area is fun. Looks like it’s involved in a load of tasks… so if a patient has a lesion there, then you might expect performance in a load of tasks to be impaired. Not so. Patient AP lost most of his rPFC as the result of an RTA, yet has superior performance on a load of tasks. He also showed excellent social skills. His ability to multitask, e.g., as demonstrated by performance on the Multiple Errands Task (this involves throwing people in a supermarket—a real one—and getting them to do tasks like buying bread and working out what town had the coldest temperature the day before), however, was much worse than controls. This has also been shown for several other patients, as has impairement on the six elements task which… involves giving people six tasks, and asking them to switch between them under time constraints and whilst following certain rules.

What about other tests of executive functions? WCST – okay. Tower of London – okay. Cognitve Estimates Task (e.g., just how many camels are there in Italy?) – okay. Stroop – okay.

Patient with left hemisphere rPFC (keeping up with these brain regions, dear reader?) were found to be okay at individual tasks, but performed poorly at switching between them in comparison to controls. How cool is this? They voluntary switched tasks less frequently and spent longer on the individual tasks. Perseverance? Is this related to autism? Hmmmm!

That’ll do for now.

Reference

Paul W. Burgess, Jon S. Simons, Iroise Dumontheil, and Sam J. Gilbert. (2005). The gateway hypothesis of rostral prefrontal cortex (area 10) function. In J. Duncan, L. Phillips, & P. McLeod (eds.), Measuring the Mind: Speed, Control, and Age. Oxford University Press, Oxford. pp. 217-248.

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One comment

  1. Pingback: Top-down versus bottom-up « Figural Effect

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