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Lesioning Definition Psychology: Understanding Brain Lesions and their Effects

Lesioning Definition Psychology: Understanding Brain Lesions and their Effects

If you’re interested in the fascinating field of psychology, you’ve probably heard of lesioning. In short, lesioning is the process of intentionally damaging a specific area of the brain to study its effects on behavior and mental processes.

Lesioning has been used for decades in the field of neuroscience to learn more about how the brain works. In this article, we’ll explore the definition of lesioning in psychology, how it’s used, and what researchers have learned from it.

What is Lesioning?

Lesioning is the process of intentionally damaging or destroying a specific area of the brain to observe the changes in behavior and mental processes that result. This can be done in several ways, including:

  • Surgery
  • Chemical injections
  • Radiation
  • Electrical stimulation

The goal of lesioning is to identify the function of a specific area of the brain or to learn how that area of the brain relates to a particular behavior or mental process. By comparing the behavior or mental processes of someone before and after a lesion, researchers can draw conclusions about the role of that particular area.

Types of Lesions

There are several types of lesions that can be induced in the brain depending on the research question:

Brain Lesions by Location

  • Cortical Lesions: This type of lesion occurs on the surface of the brain in the cerebral cortex.
  • Subcortical Lesions: This type of lesion occurs beneath the cerebral cortex and can have more extensive effects on brain function.
  • Cerebellar Lesions: These are lesions of the cerebellum, which is responsible for coordination and balance.

Brain Lesions by Method

  • Aspiration Lesions: This type of lesion removes specified parts of the brain by sucking up the targeted area with a needle.
  • Radio Frequency Lesions: Radio frequency is an effective tool to destroy brain tissue with heat.
  • Cryogenic Lesions: This type of lesion destroys brain tissue by freezing it with a special cryogenic substance.
  • Chemical Lesions: This type of lesion involves the injection of chemicals that selectively destroy neurons within a specific area of the brain.

Brain Lesions by Purpose

  • Reversible Lesions: These lesions are induced with the anticipation of reversing normal brain function.
  • Irreversible Lesions: These lesions typically involve the destruction of brain tissue, which leads to permanent damage.

What Have We Learned from Lesioning Studies?

Lesioning has been used to explore many different brain areas and their functions. Below are some of the notable insights that researchers have gained through lesioning studies:

The Cerebellum and Motor Control

By inducing lesions in the cerebellum, researchers have discovered that the cerebellum plays a crucial role in motor coordination and balance. Lesions in this area can lead to a gait disturbance, tremors, and an overall lack of coordination.

Broca’s and Wernicke’s Areas

In the late 1800s, Paul Broca and Carl Wernicke discovered two specialized areas of the brain that are critical for language processing: Broca’s area and Wernicke’s area. Lesioning studies have corroborated that Broca’s area is responsible for speech production while Wernicke’s area is responsible for understanding speech.

The Hippocampus and Memory Formation

Lesioning studies on the hippocampus, a region of the brain that plays a critical role in memory formation, have been particularly productive. Researchers have discovered that the hippocampus plays a crucial role in the formation and retrieval of memories. Lesions in the hippocampus can cause amnesia or an inability to form new memories.

Criticisms of Lesioning Studies

While lesioning has been a powerful tool, it is not without its critics. Critics argue that the type of lesions induced in studies is often extreme and not necessarily reflective of normal brain damage caused by disease or trauma. Additionally, critics claim that lesioning is inherently unethical because it involves intentionally damaging the brain. Therefore it is not compatible with modern ethical standards in research practice.


Though it has some critics, lesioning is invaluable in advancing our understanding of the human brain. Because it allows scientists to observe the consequences of damaging specific areas of the brain in a controlled setting, lesioning has brought incredible insights into several brain areas’ functions.

It’s clear that the lesioning definition in psychology has certainly broadened our horizons on brain functionality and conditions. Whether it is studying the role of different brain areas in cognition, emotion, or behavior, lesioning will undoubtedly continue to play a vital role in advancing our knowledge of the brain’s functions.