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Hanna Damasio, Disorder of Social Conduct Following Damage to Prefrontal

Cortices, [in:] J.-P. Changeaux, A.R. Damasio, W. Singer, Y. Christen (eds.), Neurobiology of

Human Values, Springer 2005, pp. 37-46.

1. Summary

(a) Theses

Thesis 1: Certain disorders of social conduct in which ethical rules are violated can be related

to specific brain systems (ventromedial prefrontal cortices VMPFC) and accounted for by

neural dysfunction in the absence of causative sociocultural factors.

Thesis 2: Abnormal emotional function seems to play a critical role in disorders of social

conduct.

Thesis 3: VMPFC region is necessary for triggering most of salient social emotions.

(b) Experimental setting

Experiment 1: Normal subjects and patients with an adult-onset damage to VMPFC region

were presented with The Iowa Gambling Task (IGT). The task involves selection of cards

from four decks (A, B, C and D). The subjects is told that each card selection can result in a

money gain or loss. The subject is given $2.000. The subject does not know that: (1) the

rewards in A and B are always $100, whereas in C and D are $50; (2) the penalties in A and B

are up to $1200, whereas in C and D up to $300; (3) the game lasts for 100 turns; (4) turning

cards from A and B leads to an overall loss, in spite of immediate high rewards, whereas

turning cards from C and D is profitable. VMPFC patients turn more cards from A and B

decks, ending in their bankruptcy. Normal subjects turn more cards from decks C and D.

Experiment 2: The IGT can be played while skin conductance responses (SCR) are

monitored. SCRs occur immediately after a punishment or reward (,,consequent SCR) and in

the 5 sec interval preceding the actual choice of a card (,,anticipatory SCR). Both normal

subjects and VMPFC patients show similar consequent SCR amplitudes (higher after a

punishment, lower after a reward). However, normal subjects show anticipatory SCRs that

discriminate between the decks (higher amplitudes for ,,bad decks A and B, lower amplitude

for ,,good decks C and D), whereas VMPFC patients anticipatory SCRs show very lowamplitude for all decks.

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Experiment 3: The VMPFC patients perform normally in tests measuring their cognitive and

social problem-solving abilities.

Experiment 4: Patients with an early-onset damage to VMPFC region were studied (lesions

acquired between the age of 1 and 7). Such patients perform abnormally on all tests probing

their social problem-solving abilities, on which the adult-onset group perform normally.

Experiment 5: Both groups of VMPFC patients behave abnormally in real-life social

situations, showing severe impairment in their social emotions recognition (shame,

embarrassment, compassion). However, the behavior in such situations is especially abnormal

for patients with an early-onset damage to VMPFC region.

2. Critical comments:

1) Although VMPFC region seems to be a necessary structure for normal, real-life decision

making in situations when some ethical rules are evaluated, it is plausible to assume that other

brain structures also play an important role in the process of making such decisions. In

particular, it seems that structures responsible for cognitive functions are a necessary element

while making such decisions.

2) It would be interesting to examine which of the other brain regions are necessary for

making the aforementioned decisions.