Biological Psychology: Neurons, Glial Cells, and Neural Communication

Biological Psychology: Foundations

Neurons: The Brain’s Communicators

Neurons are the fundamental units of the nervous system, specialized for communication. They transmit information via electrical signals known as action potentials.

• Definition: Neurons are nerve cells that communicate with each other to process and transmit information.

• Role: Serve as the building blocks of the nervous system.

• Action Potentials: Electrical impulses that travel along the neuron to convey information.

• Example: Sensory neurons transmit signals from the skin to the brain when you touch a hot surface.

Neural Components

Neurons have specialized structures that facilitate their function.

• Cell Body (Soma): Contains the nucleus and builds new cell components.

• Dendrites: Branch-like extensions that receive information from other neurons.

• Axon: Long tail-like structure that transmits information away from the cell body.

• Axon Terminals: Knobs at the end of the axon containing synaptic vesicles filled with neurotransmitters.

• Synapse: The junction between neurons where communication occurs via neurotransmitters.

• Mnemonic: "Dendrites listen, axons speak!"

Glial Cells

Glial cells are non-neuronal cells that provide support and protection for neurons.

• Definition: "Glial" means glue; these cells are plentiful in the brain.

• Functions: Support, nourish, and protect neurons; involved in psychological functioning (e.g., production of myelin).

• Bodyguards: Feed and protect neurons.

• Example: Oligodendrocytes in the central nervous system produce myelin.

Myelin and Multiple Sclerosis

Myelin is a fatty insulation produced by glial cells that surrounds axons, increasing the speed and efficiency of electrical signal transmission.

• Function: Insulates axons and speeds up neural communication.

• Multiple Sclerosis (MS): A disease characterized by the loss of myelin, resulting in erratic neural signaling and impaired function.

How Does a Neuron Fire?

The process of neural firing involves several steps, each crucial for proper communication.

1. Step 1: Resting Potential

   • Neuron is polarized: negative inside, positive outside.

   • Membrane is selectively permeable, preventing sodium ions (Na+) from entering.

   • Equation: $V_{rest} \approx -70\,\text{mV}$

2. Step 2: Action Potential

   • Brief electrical charge travels down the axon.

   • When stimulated, gates open and Na+ rushes in, depolarizing the neuron.

   • All-or-none law: a neuron either fires completely or not at all.

   • Frequency of action potentials encodes intensity of stimulus.

   • Equation: $\text{Action Potential:}~ V_{m} \rightarrow +40\,\text{mV}$

3. Step 3: Repolarization

   • Potassium ions (K+) flow out, restoring negative charge inside the axon.

4. Step 4: Return to Resting Potential

   • Neuron resets to its original polarized state.

5. Step 5: Refractory Period

   • Brief period during which the neuron cannot fire, regardless of stimulation.

Electrochemical Communication

Neurons communicate through a combination of electrical and chemical processes.

• When an action potential reaches the axon terminal, it triggers the release of neurotransmitters into the synapse.

• Neurotransmitters bind to receptors on the dendrites of the receiving neuron, transmitting the signal.

• Excitatory messages: Increase the likelihood that the receiving neuron will fire.

• Inhibitory messages: Decrease the likelihood that the receiving neuron will fire.

• Example: Glutamate is an excitatory neurotransmitter, while GABA is inhibitory.

Summary Table: Key Neural Components

Component	Function
Neuron	Transmit electrical signals
Dendrite	Receive information
Axon	Send information
Glial Cell	Support, nourish, protect neurons
Myelin	Insulate axons, speed transmission
Synapse	Site of chemical communication

Additional info:

• Neural communication is foundational for understanding behavior, cognition, and psychological disorders.

• Disruptions in neural signaling (e.g., MS, neurotransmitter imbalances) are linked to various neurological and psychological conditions.