Question

A surgeon places an electrode on a portion of your brain and stimulates it. Immediately, your right wrist involuntarily twitches. The doctor has most likely stimulated a portion of the______________ area of your brain.

Short answer

The doctor has most likely stimulated a portion of the motor cortex area of the brain.

Step-by-step solution

Identify the Principle

The principle being tested here is whether or not we understand that the brain controls the movements of our body parts. When a certain area of the brain is stimulated, it can cause an associated body part to move.

Critical Analysis of the Question

The question states, the right wrist twitched when a specific area in the brain was stimulated, which shows that this part of the brain controls movements of the right hand.

Relate the Information with Known Facts about Brain

Based on neuroscience, we know that the left hemisphere of the brain controls the movements of the right side of the body and vice versa. Therefore, the part of the brain that was stimulated must be located in the left hemisphere.

Identify the Brain Area

The part of the brain that controls movement is the motor cortex. Given that the example involves movement of the right hand, the doctor must have stimulated the motor cortex in the left hemisphere of the brain.

Key concepts

Brain Hemispheres

The human brain is an incredibly fascinating organ, and it’s divided into two halves known as the left and right hemispheres. Each hemisphere may appear symmetrical, but they have some distinct functions.

• The left hemisphere is generally more involved in logical reasoning, language, and analytical tasks.
• The right hemisphere, on the other hand, often contributes to creativity, spatial ability, and visual imagery.

One particularly interesting function of brain hemispheres is their control over the opposite side of the body. This is known as contralateral control. For instance, the right hemisphere processes information and controls movement for the left side of the body, while the left hemisphere does the same for the right side.
This is why, when the motor cortex in the left hemisphere is stimulated, it can cause involuntary movements in the right side, like the wrist twitch described in the exercise.

Neuroscience

Neuroscience is the scientific study of the nervous system, an intricate network that includes the brain, spinal cord, and peripheral nerves. It helps us understand how brain structures and functions correlate with behaviors and bodily functions.
At the core of neuroscience is the concept of neuroplasticity, which is the brain's ability to reorganize itself by forming new neural connections throughout life. This capacity allows the brain to adapt to new experiences and recover from injuries.
Several key branches of neuroscience examine different aspects:

• Cognitive neuroscience focuses on understanding the neural bases of cognitive processes.
• Molecular neuroscience delves into the chemistry and biology of neurons.
• Clinical neuroscience examines the disorders of the nervous system, looking for ways to remedy them.

By studying neuroscience, we gain insights into how activities like stimulating a part of the motor cortex can influence physical movement.

Body Movement Control

Body movement control is a complex process orchestrated primarily by the brain. The motor cortex plays a crucial role in this control by sending signals through motor neurons to muscles, facilitating movement.
When we decide to move a limb, it starts with a signal in the motor cortex, part of the brain's frontal lobe. This area generates neural signals that travel down the spinal cord and out to muscles, prompting them to contract or relax.
There are two main types of movements:

• Voluntary movements, which we consciously control, like writing or walking.
• Involuntary movements, such as the reflex actions or twitching in response to external stimuli, as seen in the exercise scenario.

The intricacies of body movement control also involve sensory feedback, where information from muscles and joints goes back to the brain to fine-tune movements, ensuring coordination and balance.