Understanding the Nervous System and Mind-Body Concepts

The Nervous System

The nervous system is a biological system that enables very complex beings to interact with what surrounds us. We can say that it is a huge network responsible for the collection of internal and external stimuli. It processes these stimuli to generate the response that the decision center (brain) considers optimal.

There are two main divisions:

• Central Nervous System: Consists of the brain and spinal cord.
• Peripheral Nervous System: Includes all the nerves of the body that connect internal and external stimuli to the central nervous system.

Peripheral Nervous System

The peripheral nervous system includes different types of nerves:

• Sensory Nerves: Transmit information from sensory receptors (like those for touch, pain, temperature) to the brain. For example, if you burn yourself, sensory nerves signal to the brain that you are burning.
• Motor Nerves: Transmit information from the brain to the muscles and glands that execute the response.

Central Nervous System

The central nervous system is composed of the brain and spinal cord. Key parts include:

• Cerebellum: Coordinates body balance and voluntary movements.
• Brainstem: Controls vital physiological functions such as breathing and heartbeat.
• Spinal Cord: Contains all nerve connections between the brain and the rest of the body. Many instinctive or reflex acts are processed directly by the spinal cord without reaching the brain (for example, withdrawing your hand quickly when you touch something hot).
• Cerebrum: Consists basically of neurons. Neuronal activity involves electrical impulses and chemical signals.

Synapses

Synapses are the junctions between neurons. When neurons are activated or 'fire', an electrical current propagates along the neuron. At the synapse, this electrical current triggers the release of chemicals called neurotransmitters, which transmit the signal to the next neuron.

Functionalism

Functionalism explains the mind-body connection using a computer metaphor:

• Software: Represents the program (the mind).
• Hardware: Represents the physical computer system (the body).

According to this view, different software (programs) can run on the same hardware through various electrical connections.

Supervenience

Supervenience in the philosophy of mind suggests that there is no mental activity without corresponding brain activity. Mental states are dependent upon and determined by physical brain states.

Gedanken Experiment (Brain in a Vat)

A thought experiment involving a brain properly connected to a computer in charge of simulating the peripheral nervous system. The key components and steps are:

1. Irrigate the brain with blood to keep it alive.
2. Connect the brain to an artificial nervous system (the computer). The computer is connected to nerve endings simulating sensory input.
3. The computer sends impulses to the brain, which are received as sensory information.
4. The computer processes information and simulates the body's response, like muscle movements.

A key point often raised is the lack of actual muscle response from the brain in this scenario.

Emergent Materialism

Emergent materialism proposes that the mind emerges from matter (the physical body). It is unable to conceive the evolution of the mind without it being joined to the body.

The human mind depends on various systems and levels of the brain that work in a complex neural organization, not from a single central point. Every human brain is different, just as every face of every person is different. This complexity complicates the study of the brain.

Aphasia

Aphasia occurs when a part of the brain responsible for language is damaged, resulting in difficulty with speaking, understanding, reading, or writing.