Question

Hi. This is a question for my summer neuroscience class.

Q: Why must we move on from the lesion-deficit tradition? Give at least 3 points.

Answer 1

Lesion-deficit tradition of neuroscience-

Before functional imaging ( Magnetoencephalography, Electroencephalography, Functional magnetic resonance imaging) was available, the human nervous system was studied with the help of the Lesion-deficit method.

In this method, the behavior of a patient with suspected brain damage was noted, and later his/her brain was studied postmortem. The patient's signs and symptoms were attributed to the brain lesion.

Example - If a patient is unable to speak but is able to understand and on post mortem, there is a lesion in the posterior part of the left inferior frontal gyrus, it was concluded that the posterior part of the left inferior frontal gyrus is responsible for speech production.

We must move on from this tradition because:

1. No control over the lesion location - the lesion will depend on the size and type of trauma that the patient suffered. This limits our capacity of deciphering secrets of various parts of the brain.
2. Lesions are large - there is overlap between various parts of the brain. As a result, attributing a deficit of function to a damaged brain part ( based on this model ) becomes an oversimplification. As a result, there is very little spatial resolution.
3. Individual subjects serve as evidence - this is not a good thing will studying neuroscience, because no two people will have the same type of lesion. Therefore, there is high level of variability.