Astral Codex Ten

PFC

4 min read

PFC

Article

PFC is a recurring concept in the Astral Codex Ten archive, appearing 2 times across 2 issues between September 30, 2022 and October 31, 2022. The archive places it in contexts such as “A ‘state prediction error’ or general surprise signal from PFC”; “in PFC (via the mesocortical pathway), it draws attentional resources”. It most often appears alongside dopamine, fMRI, mesocortical pathway.

Metadata

  • Category: Concepts
  • Mention count: 2
  • Issue count: 2
  • First seen: September 30, 2022
  • Last seen: October 31, 2022

Appears In

None.

Source Context

Recovered passages from the original issue text. When the raw archive preserved outbound links inside the source passage, they are listed directly under the quote.

Highlights From The Comments On Unpredictable Reward
September 30, 2022 · Original source
One neuroscientific perspective on this is that in order for dopamine to track reward prediction *error* (RPE), it is logically necessary that some other piece of neural circuitry track reward prediction *per se*, often called "value." Those of us who think that dopamine is computing RPE on a moment-by-moment basis (the first derivative of value; see Kim, Malik et al., Cell, 2020) therefore generally also believe that some other part of the brain, especially the ventral striatum (aka nucleus accumbens) and perhaps also the prefrontal cortex, maintains an estimate of value that gets updated by dopamine. And indeed, there are dozens of papers reporting that neural firing in these brain regions correlate with value over and above RPE.
That said, it is also true that (1) NAc neurons correlate strongly with value and also respond to some extent to rewards, predicted and unpredicted; (2) cocaine or amphetamine in the NAc (and another region of the ventral striatum called the olfactory tubercle), which dramatically elevate dopamine levels, elicit robust responses; and (3) in the context of the "liking vs. wanting" framework you allude to, Kent Berridge and others have argued that the NAc contains a "hedonic hotspot", along with closely linked regions like the prefrontal cortex and ventral pallidum. This is an operational definition meaning that when you infuse opioid receptor agonists into said region, the animals react with pleasure, and conversely if you lesion/block activity in these areas, they don't show these behaviors as much, or even start showing defensive behaviors.
Now, what does the released dopamine do? In PFC (via the mesocortical pathway), it draws attentional resources to the surprising stimulus and its plausible causes, gating out the processing of other, less relevant stimuli. Simultaneously, in NAc, it strengthens connections between PFC inputs and the endorphin-releasing cells, thereby wiring together the hedonic features of the reward and the sensory features of any cues predictive of it. This imbues the cue with the ability to release the GABAergic brake on VTA DA neurons all by itself. Phenomenologically, it results in us "liking" the cue as much (or nearly as much) as we like the reward (this is what allows, e.g., animal trainers to reinforce behavior with only the sound of a clicker that has previously been paired with food).
Highlights From The Comments On Jhanas
October 31, 2022 · Original source
Now, what does the released dopamine do? In PFC (via the mesocortical pathway), it draws attentional resources to the surprising stimulus and its plausible causes, gating out the processing of other, less relevant stimuli. Simultaneously, in NAc, it strengthens connections between PFC inputs and the endorphin-releasing cells, thereby wiring together the hedonic features of the reward and the sensory features of any cues predictive of it. This imbues the cue with the ability to release the GABAergic brake on VTA DA neurons all by itself. Phenomenologically, it results in us "liking" the cue as much (or nearly as much) as we like the reward (this is what allows, e.g., animal trainers to reinforce behavior with only the sound of a clicker that has previously been paired with food).