ps418

It has been known for decades, on the basis of stroke and brain lesion studies, that the prefrontal cortex plays a major role in the regulation of behavior, and particularly the inhibition of certain behaviors, such as aggression. The earliest and most famous illustration of this is the case of Phineas Gage, who in 1848 had a tamping iron shot through his skull and prefrontal cortex. Though he survived the injury, he afterwards exhibited impulsive and antisocial behavior. Since that time, there have been numerous other instances reported in the neurological literature where damage to the same brain areas are followed by radical changes in behavior, particularly a marked lack of inhibition of sexual or aggressive impulses.

One of the more interesting cases I've read about is that reported by Blair and Cipolotti (2000). Their subject, J.S., was a 56 year-old electrical engineer, who, prior to the cerebral infarction which partially destroyed his prefrontal cortices, had no psychiatric history and according to a relative was quiet and withdrawn. After the prefrontal trauma, J.S.'s behavior was "gravely disturbed," and included physical attacks on others. According to Blair and Cipolotti (2000):

Another interesting example was reported recently in the march issue of Archives of Neurology by Burns and Swerdlow (2003). Their case report involves a 40-something male, a school-teacher, husband and father with no premorbid psychiatric history. For no apparent reason, the man started to have headaches and became increasingly obsessed with sex, and increasingly unable to regulate these impulses in a socially appropriate way. After a few months, the man checked himself into a hospital, saying he was afraid he would rape his landlady.

Standard tests at the hospital revealed neuropsycological deficits, and an MRI was done. This revealed a very large right prefrontal tumor. Following resection of the tumor, the symptoms disappeared completely. However, 7 months later, the subject began experiencing both the headaches and sexual impulse control problems once again. MRI revealed regrowth of the tumor, and after a second resection of the tumor, the behavioral problems again disappeared! See Putting The Brain On Trial

Refs and further reading:

Anderson et al, 1999. Impairment of social and moral behavior related to early damage in human prefrontal cortex. Nature Neuroscience 2, 1032 - 1037.

Best et al, 2002. Evidence for a dysfunctional prefrontal circuit in patients with an impulsive aggressive disorder. Proc. Natl. Acad. Sci. U. S. A. 99: 8448-8453

Blair and Cipolotti, 2000. Impaired social response reversal
A case of `acquired sociopathy.' Brain, Vol. 123, No. 6, 1122-1141..

Burns and Swerdlow, 2003. Right Orbitofrontal Tumor With Pedophilia Symptom and Constructional Apraxia Sign. Arch Neurol. 2003;60:437-440.

Cai et al, 2002. Serotonin 5-HT1A Receptors Regulate AMPA Receptor Channels through Inhibiting Ca2+/Calmodulin-dependent Kinase II in Prefrontal Cortical Pyramidal Neurons. J. Biol. Chem. 277: 36553-36562

Damasio et al, 1990. Individuals with sociopathic behavior caused by frontal damage fail to respond autonomically to social stimuli. Behav Brain Res 41: 81�94.

Davidson et al, 2000. Dysfunction in the Neural Circuitry of Emotion Regulation--A Possible Prelude to Violence. Science 289, pp. 591-594.

Kim et al, 2002. Inability to control anger or aggression after stroke. Neurology 58: 1106-1108

New et al, 2002. Blunted Prefrontal Cortical 18Fluorodeoxyglucose Positron Emission Tomography Response to Meta-Chlorophenylpiperazine in Impulsive Aggression. Arch Gen Psychiatry 59: 621-629

Shamay-Tsoory et al, 2003. Characterization of Empathy Deficits following Prefrontal Brain Damage: The Role of the Right Ventromedial Prefrontal Cortex. Journal of Cognitive Neuroscience 15:324-337.

Patrick

Majestyk

Am I mistaken or would the assertion that, the prefrontal cortex acts in more of a reactive manner in response to an emtional impulse, be consistent with the concept of social behavior as an evolutionary development?

Calzaer

So, wait...
damage to a physcial part of the brain causes people to engage uncontrollably in acts commonly considered to be "sins"?

Hmmmm...

(I just make the connections, I don't interpret them. )

ps418

If I understand you, then I would think the answer is yes. The prefrontal cortex is far more developed in humans than in our closest relatives (Semendeferi et al, 2001). As the examples cited in the refs above show, the prefrontal cortices in particular can act like brakes that inhibit you from acting impulsively. The frontal lobes in general are involved in all sorts of other higher-level cognitive functions that are required for complex social behavior (see Stuss and Levine 2002 for a review), including what is called "theory of mind" (Stone et al, 1998) which is more or less the ability to make inferences about other's people's mental state, and which is obviously crucial to high-level social behavior. Even though there is social behavior in primates and other groups, it is much more sophisticated in humans, and this surely must be due in part to our enhanced prefrontal cortex and frontal lobes in general. So I guess you could say that the evolution of these brain structures allowed for the emergence of complex social behavior.

Semendeferi et al, 2001. Prefrontal cortex in humans and apes: a comparative study of area 10. Am J Phys Anthropol 114(3):224-41.

Stuss and Levine, 2002. Adult clinical neuropsychology: lessons from studies of the frontal lobes. Annu Rev Psychol 53:401-33.

Stone et al, 1998. Frontal lobe contributions to theory of mind. J Cogn Neurosci 10(5):640-56.

Patrick

Pyrrho

Thank you ps418 for providing such an interesting thread. I wonder what the defenders of a non-compatibilist version of "free will" have to say about such things...