Broca (1861)

Localisation

Broca (1861)

Case study on Louis Leborgne (Tan), whose brain was autopsied after death, he could understand speech but not produce it; found major damage to the left frontal lobe

Aim

• To see areas in the brain that dealt with the functions of speech

• To investigate whether certain functions can be localized in specific areas of the brain

Sample

Broca described 25 additional patients with the same problem before asserting that speech articulation is controlled by the left frontal lobe.

Procedure

Looked at a man (tan) who couldn't speak properly (could only say ‘tan’) after he passed away, and found the damaged area in the brain in the frontal lobe. He did this with other patients over time as well. Studying a patient with a natural occurring brain lesion and conducting an autopsy after the patient's death

Results

An autopsy revealed a lesion in the left frontal lobe. The specific placement is now called Broca’s area, and has been found to be responsible for the co-ordination of the motor (muscle) movements required to produce coherent speech, the area allows one to combine sounds into words.

Conclusion

Broca concluded that parts of the left frontal lobe, including the area damaged in Tan, had the role of the “language centre” in our brain. Many subsequent studies have confirmed the role of Broca's area in the production of speech. 

Broca's aphasia

Loss of articulated speech due to lesion in the frontal area of the left hemisphere, in particular a region in the posterior inferior frontal gyrus (now known as Broca's area)

Strengths of Broca (1861)

- Old study, applied today and still correct, developed medical aid to those with Broca's aphasia

Limitations of Broca (1861)

• The area responsible for articulate speech may be more complex than we would like to think.

• Tan's brain was re-examined more than a 100 years later and the lesion was actually much broader than documented by Broca (old study, no modern technology, he preserved the brain rather than dissecting it)

• Lesion is rarely neat or confined to one area

• You have to with till the patient is dead

• One participant lack of generalizability