This looks like a good perspective of brain evolution in the context of reward-based learning/problem solving.
Animals evolved as award seekers, evolutionary view of reward from 3 main clades: early vertebrates, early mammals, and primates.
The opening section talks about the history of brain-evolution science. Many pitfalls, controversy and disargreement, lots of people were just completely wrong.
Some definitions:
Homology: A structure or behavior is homologous to another if two or more descendant species have inherited it from their most recent common ancestor.
Analogy: ancestor. Analogy is a statement about function, not ancestry. A structure or behavior is analogous to another if it subserves the same function. The classic example involves wings. Insects, birds, and bats have wings
Homoplasy: something similar that has evolved in different lineages through parallel or convergent evolution.
Invertebrates are arbitrary grouping, protostomes are group of insects, mollusks and segmented worms. Also deuterostomes, which separated 600 MYA. Protostomes and vertabrates have evolved tremendously since our common ancestor. Vertabrates evolved with deuterostomes.
Three cladograms, arranged from top to bottom. The middle and bottom cladograms each develop one of the lineages from the cladogram above, as shown by the connecting arrows. The circled letters, A, B, and C, reference common ancestors referred to in the text. Beneath the names of selected clades, which are outlined in boxes, shared derived traits appear in italics. Abbreviation: DA, dopamine.
The telencephalon and early dopamine system were most important evolutionary developments. Early telencephalon was olfactory bulb and a homologue of piriform cortex. Contained homologue of basal ganglia and probably amygdala and hippocampus.
Mammals use a mixture of old and new features to deal with reward. New: neocortex. Hipp and piriform are still allocortex, there's some transition cortical areas. Rodents have similar prefrontal architecture, but not completely homologous to primates.
Primates have main type of frontal lobe: agranular cortex (no layer 4) and areas with subtle layer 4, collectively called granular prefrontal cortex (PFg). This is a primate innovation as all primates have PFg. Rodents have the agranular parts.
Nonvertabrates can deal with reward, associative learning (pavlovian) seems to be something before protostome/deuterostome split. Instrumental conditioning also shown in invertabrates.
Dopamine System: regulates the classical conditioning method, error signal etc. Dopamine could be acting across several orders of time to influence reward-based behavior.
Basal ganglia: confounded because of its role in both reward and movement processing, but seems to be movement regulated by reward -- computes the cost of energy requirements. "Bradykinesia represents an implicit decision not to move fast because of a shift in the cost/benefit ratio of the energy expenditure needed to move at normal speed."
Amygdala: Reinfocer devaluation == stop eating once you're satieted. Amygdala lesions remove this ability. Lots of other roles, delay signal, affective signals, controls quicker behavioral changes.
Hippocampus: Spatial computations. Large place fields may involve recognition of contexts and could be important for reward processing.
Neocortex in mammals has allowed for even more control over reward. Agranular FC is homologous in rodents and primates although there are now differences from the last 10 MYA of evolution. Mammals have imporved "executive function", mediated by agranular frontal cortex, including top-down modulatory function that biases competition among different brain systems engaged in and competing for control of behavior.
Mammals have: anterior cingulate (AC), infralimbic (IL), prelimbic (PL), agranular orbital frontal (OFa) and agranular insular (Ia). These different parts afford mammals greater flexibility in their reward-seeking behavior. Ia gets many visceral signals -- Ia functions in interoception pain, itch, temperature, metabolic state, lungs, heart, baroreceptors and digestive tract.
Several dissociated memory systems combine to guide reward-seeking behavior. Nonmammalian vertebrates (birds, reptiles), appear to have problems overriding their innate behavioral responses.
Anterior Cingulate: biases behavioral control towards one among multiple competing stimuli. Weighs the cost-benefit: is reward worth the effort? AC allows the animal to weigh more behavioral options (it can present the reward system with more possible behavioral choices).
Prelimbic cortex: involved in regulating goal-directed behaviors in cases where they compete with habitual stimulus-responses. Helps encode the response-outcome associations (but not execution of them).
Inframlimbic cortex: seems to be opposite of PL, promotes behavioral control of S-R associations. Plays a role in extinction learning -- biases behavior towards more recent newly learned rules (that a stimulus no-longer gives reward) than to the older more stongly associated rules).
Orbitofrontal Cortex: problems between rodent and primate OFC -- no homolog in rodents with granular orbitorfrontal (PFo), only agranular has homolog (OFa). Neural activity in OFa reflects reward expectation, especially sensory-specific properties of the reward. OFa lesions impair ability to make decisions on basis of reward expectations.The OFa contributes more to learning the associations between CSs and the sensory aspects of reward (e.g. taste). It doesn't compute the biological value per se.
Agranular Insular Cortex: Relates sensory properties of the reward to the instrumental motivations, playing a complementary role to OFa. This means that Ia and OFa likely store the sensory related properties of rewards such that they can be used during recall to help evaluate different reward-based decisions.
Primates have PFg -- granular parts of frontal cortex. Also extra sensory areas like IT. Granular orbital frontal (PFo) gets strong projections from IT and other posterior sensory areas including auditory cortex. PFo is one of earliest sites for convergence of visual information with visceral inputs. Primates can then link visceral, olfactory and gustatory inputs with high-order visual stimuli. PFo represents high-level details and conjunctions of sensory features for rrewards, the magnitude of reward, the probability of reward and the effort required to obtain it. Computes reward in a common currency to pit risk vs. reward in decisions.
Can learn rules and strategies for rewards instead of stimulus and action relations to outcomes. Can dissociate the emotional value of reward with a value-less reward signal.
Humans can do longer term learning, and "mental time-travel" which help them with reward processing. Further they can talk about reward and have secondary rewards -- i.e. I don't want to want to smoke.
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