Illustrate decision making properties of lip decision-making) neurons. Why do we call lip neurons – decision making neurons?

LIP is an integrative neurons, which accumulate information about decision option and filter out noise. LIP are the decision making neurons which process perceptual decisions. Their activity increases faster if decision is easy.

LIP codes probability and value

Эксперимент: обезьяна должна была решить в каком направлении движутся точки на экране. Перед каждой пробой на экране появлась подсказка в виде геометрической фигуры того или иного цвета, которая означала в каком направлении будут двигаться точки. Правильные решения были награждены соком.

Условие 1: Манипулировали количеством полученного сока. Активность LIP была выше, когда обезьяна ожидала получить больше сока.

Условие 2: Манипулировали вероятностью получения награды. Активность LIP была выше, когда обезьяна ожидала с большей вероятностью получить сок.

Please explain the following terms:

Utility is a measure of the desirability of consequences of an action.

Ordinal utility – relative utility, while the utility of a particular good and service cannot be measured using a numerical scale, different alternatives can be ordered into worse, equal or better.

Cardinal utility – assign number to choices and then compare them,a theory of utility under which the utility gained from a particular good or service can be measured and that the magnitude of the measurement is meaningful.

Neuroeconomics utility –the averaged firing rate (real number: 0,2,…1000 etc) of a population of neurons that encodes the subjective value of the object. It predicts choices.

Expected utility theory - to each alternative is assigned a weighted average of its utility values the probabilities of outcomes EU = Σ p U. We take into account uncertainty of outcomes while decision making process. We are aware of uncertainty of the outcomes.

Explain the functional role of the orbitofrontal cortex (ofc)

The orbitofrontal cortex (OFC) is a prefrontal cortex region in the frontal lobes in the brain which is involved in thecognitive processing of decision-making. 

The human OFC is among the least-understood regions of the human brain; but it has been proposed that the OFC is involved in sensory integration, in representing the affective value of reinforcers, and in decision-making and expectation.^[1] In particular, the OFC seems to be important in signaling the expected rewards/punishments of an action given the particular details of a situation.^[6] In doing this, the brain is capable of comparing the expected reward/punishment with the actual delivery of reward/punishment, thus, making the OFC critical for adaptive learning. 

Function – comparison of two options. OFC supervises NA. Large area in the basement of the brain just above our eyes. Integrates multiple sources of information, compares different options. This region is closely linked to DLPFC involved into cognitive control.

OFC serves as a mediator between NA and Amygdala, as in diffusion model. IT compares signals from these centers of expected rewards and costs and integrates given information to produce decision.

Experiment 1:

Monkey decide which drink to choose A or B in different proportions. Depending on the proportion preference shifts from drink A to drink B. Ideal signal coding relative preferences would have U shape.

When the option is strongly preferred OFC has the highest activity. The clearer the choice is the higher activity is.

Experiment 2:

In marketing. Participants tasted wine, the same wine was indicated as cheap or expensive. The activity of neurons in OFC was the highest when wine was claimed expensive. Despite the fact that actual quality stays the same, OFC reacted differently because in case with high price the relative preference was higher.