Postmortem studies

Postmortem studies are a neurobiological research method in which the brain of a patient, usually the subject of a longitudinal study, with some sort of phenomenological affliction (i.e. cannot speak, trouble moving left side of body, Alzheimer’s, etc.) is examined after death. The irregularities, damage, or other cerebral anomalies observed in the brain are attributed with whatever ailment the patient was afflicted with in life. With repeated studies a more exact correlation can be ascertained.

Background

Postmortem studies have been used to further the understanding of the brain for centuries. Before the time of the MRI, CAT Scan, or X-ray it was one of the few ways to study the relation between behavior and the brain.

Broca

Paul Broca used postmortem studies to link a specific area of the brain with speech production.

His research started when he noticed that a patient with an aphasic stroke had lesions in the left hemisphere of his brain. His research continued and his theory held up overtime.

Most notable of his research subjects was Tan (named for the only syllable he could utter). Tan had lesions in his brain caused by syphilis. This lesion was determined to cover the area of the brain important for speech production.

The area of the brain that Broca identified is now known as Broca's area and damage to this section of the brain can lead to Broca's aphasia.

Wernicke

Karl Wernicke also used postmortem studies to link a specific area of the brain with speech production. However his research focused more on patients who could speak, but whose speech made little sense and/or has trouble understanding spoken words or sentences.

His research in language comprehension and the brain also found it to be localized in the left hemisphere, but in another section. This area is now known as Wernicke's area and damage to this section can lead to Wernicke's aphasia.

Limitations

While postmortem studies can be very useful in linking the brain and behavior it still has its limitations.

The very thing that makes it such a great research method is its greatest weakness. The researcher is studying a human and his brain. However, getting a hold of person’s brain, even from one who is a subject of a longitudinal study, can be difficult. Furthermore, the rarity of the affliction studied may also affect the scarcity of the needed brain.

Also, brain damage is what being studied. It is possible that there might be too much damage to pinpoint any specific area of the brain as being responsible.

References

Sternberg, R.J. (2006). "Cognitive Psychology, Fourth Edition". California: Thomson Wadsworth.