1. Brain Lesions:
This involves the destruction of tissues, which are often caused by strokes, tumors or accidents. It is one of the oldest used to examine cognitive process which has greatly increased our understanding of the organization of the brain. However, the individuals with brain lesion often compensate for they defect within a short period of time, which makes the research finding conclusive.
2. Regional Cerebral Blood-flow Studies (RCBF):
In this technique researchers inject a small amount of radioactive substances which resembles glucose (brain's major metabolic fuel) and then record the cerebral blood flow into the active part of the brain ( as the active part of the brain requires more metabolic fuel). As different cognitive task increases, the regional blood flow into the different areas of the brain. The research can give various tasks to the subject and record the areas of the brain which are activated. The technique is also used to classify the distinction between different types of memory. This technique is also known as Position Emission Tomography (PET).
3. Evoked Potential Technique:
In this technique researchers place electrodes on a person's scalp to record electrical signals generated from a large number of neurons, located underneath electrodes. Unlike RCBF technique, this technique cannot identify the response of single neuron, but it will identify the electrical changes over very brief period of time.
4. Single Cell Recording Technique:
This technique cannot be safely used on humans. Therefore, researchers used this technique on animals, where they insert a tiny electrode into a single neuron in order to study characteristics of nervous system.
Hubel and Wiesel (1965, 1975) using this technique found that some kinds of cells in the visual cortex responded vigorously only when lines were presented in a specific orientation. Other kinds of cells are even more specific in their preference.
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