Neurobiology: Definition & Methods |

Neurobiology deals with the structure and functioning of the nervous system. It explains how information is transmitted and processed in the body.

Neurobiology as a science

Compared to other areas of biology, neurobiology is a young and multidisciplinary branch of science. It was only around 100 years ago that science was able to prove that brains consist of interconnected cells and thus form a complex, interwoven network.

In neurobiology, the basics of information processing in the animal and human nervous system are researched.

Among other things, brains and internal processes are examined for this purpose. The human brain consists of around 100 billion neurons, which are networked in parallel via an estimated 100 trillion synapses. It thus forms the top control center of our body and is of great interest for neurobiology. On a smaller scale, the synapses, the connection points between the nerve cells, or the cell activities of the neurons are of particular interest.

The goal of neurobiology is to understand which mechanisms, processes and principles work in the body, which then lead to a certain behavior or cognitive state.

Neurobiology – Topics

Different organs, cells and molecules play a major role in neurobiology. Here you will find an overview of the central topics.

nervous system

The incoming stimuli are converted and processed in the nervous system. Neurons and glial cells play a central role in nerve tissue.

The nervous system can be divided based on anatomy or function:

Classification based on anatomy:

Division based on function:

• Somatic nervous system, controls conscious or voluntary processes
• Autonomic nervous system controls unconscious or involuntary processes

neuron

With the help of the sensory organs and the nervous system, people gather information about their environment. Sensory cells convert environmental stimuli into electrical stimuli. Neurons, also called nerve cells, transmit this excitation.

The human body contains billions of nerve cells that work together to process information. Once the information from the environment has been processed, stimuli are conducted via nerve cells to the effector organs. There they trigger a reaction.

A neuron consists of three cell sections:

• Soma (cell body)
• dendrites (short extensions)
• Axon (long process) with terminal knobs

Figure 1: Structure of a neuron

axon

If we look at the axon and the enveloping membranes together, talk

we of nerve fibers. A distinction is made between myelinated and non-myelinated nerve fibers:

• Myelinated nerve fibers have a myelin sheath that insulates the axon. They are found only in vertebrates.
• Non-myelinated nerve fibers lack this insulating sheath. They occur in invertebrates and in vertebrates.

Figure 2: Schematic representation of myelinated nerve fiber (left) and non-myelinated nerve fiber (right)

resting potential

This resting potential is particularly important for the electrically excitable sensory cells, nerve cells and muscle cells. In the unexcited state, the cytoplasm of all intact neurons is negatively charged relative to its surroundings.

The resting potential is maintained by the Na-K pump under energy consumption by transporting sodium and potassium ions across the cell membrane against their concentration gradient.

action potential

This charge reversal serves to transmit the excitation of a nerve, sensory or muscle cell. Action potentials are crucial for the transmission of stimuli in the nervous system.

synapse

When the terminal button of a neuron connects to a dendrite, soma, or axon of another nerve cell, it is called a central or chemical interneural synapse. If the excitation transmission takes place from a nerve to a muscle cell, it is a chemical-neuromuscular synapse.

Furthermore, we distinguish between arousing and inhibitory synapses.

• Excitatory synapses generate a potential in the postsynaptic cell that is more positive than the resting potential of the cell (excitatory postsynaptic potential, EPSP for short).
• Inhibitory synapses reduce the resting potential of the postsynaptic cell (inhibitory postsynaptic potential, IPSP for short).

In order to trigger an action potential, the computation of EPSPs and IPSPs through spatial and temporal summation must yield a membrane potential that depolarizes the axon hillock membrane above threshold.

neurotransmitters

Neurotransmitters are stored in tiny sacs called synaptic vesicles. There are different transmitters that have different meanings and effects. Transmitter molecules and receptors fit together according to the lock and key principle.

Among the neurotransmitters we distinguish between real transmitters and neurohormones. Real transmitters tend to be short-lived messenger substances, while neurohormones have a longer lifespan.

Brain

The brain can be divided into five parts.

• hindbrain
• cerebellum
• midbrain
• midbrain
• cerebrum

The areas of the brain all contribute to the fact that the brain is capable of incredible calculation processes and that we can store information. In addition, our brains are also capable of responding to changes in anatomy and function. We call that the neuroplasticity.

receptors

Receptors are specific to the stimulus they can receive and process. According to the type of received (adequate) stimulus, receptors are divided into four groups:

photoreceptors

We find photoreceptors on the retina of the eye. The greatest concentration of photoreceptors on the retina is found in the area of ​​the optical axis, in the so-called yellow spot. There are no photoreceptors in the area of ​​​​the outgoing optic nerve, which is why it is called the blind spot.

There are two types of photoreceptors:

• Rods for light-dark vision and vision at twilight
• Cones for daylight vision and color perception

sense organs

Humans have five sensory organs that literally filter the environment for information and pass the stimuli on to the nerve cells as excitation patterns: