Search
-
- Glossary
Photoreceptors
Photoreceptors are the light-sensitive cells of the retina; they convert light into electrical potentials. There are approximately 127 million photoreceptors in the retina, including seven million cones and 120 million rods.
-
- Glossary
Fovea centralis
The fovea centralis is located in the center of the macula and is the area of sharpest vision in birds and higher mammals. Its diameter in humans is approximately 1.5 mm. There are no rods in the fovea, only cones, which are interconnected to the ganglion cells in the central area of the fovea at a ratio of 1:1, resulting in very high "resolution."
-
- Glossary
frontal
An anatomical position designation – frontal means "towards the forehead," i.e., at the front.
-
- Glossary
Frontal lobe
The frontal cortex is the largest of the four lobes of the cerebral cortex and its functions are correspondingly comprehensive. The front area, known as the prefrontal cortex, is responsible for complex action planning (known as executive functions), which also shapes our personality. Its development (myelination) takes up to 30 years and even then is not yet complete. Other important components of the frontal cortex are Broca's area, which controls our ability to express ourselves linguistically, and the primary motor cortex, which sends movement impulses throughout the body.
-
- Glossary
Frontotemporal dementia
Frontotemporal dementia is a neurodegenerative disease. Unlike Alzheimer's dementia, Pick's disease usually begins before the age of 60 and initially manifests itself through changes in personality and social behavior. There are also variants that begin with speech disorders. In advanced stages, memory performance is also impaired. The physiological cause is degeneration of nerve cells in the frontal and temporal lobes of the brain. Similar to Alzheimer's disease, the aggregation of certain proteins appears to play a role in pathogenesis. However, doctors do not yet understand exactly what happens in this process and what other factors contribute to the development of Pick's disease. Today, classic Pick's disease is only a subtype of FTD in which characteristic Pick bodies can be detected in the brain.
-
- Glossary
Functional magnetic resonance imaging
Functional magnetic resonance imaging (fMRI) is a modification of MRI that allows brain activity to be measured indirectly via regional blood flow and oxygen consumption. BOLD (blood oxygen level dependent) contrast is often used, which exploits differences in the magnetic behavior of oxygen-rich and oxygen-poor blood. An increase in the BOLD signal indicates increased neural activity. fMRI provides good spatial resolution and allows detailed conclusions to be drawn about the activity of specific areas of the brain, while the temporal resolution is in the range of seconds.
-
- Glossary
Fear conditioning
The linking of a neutral stimulus to a stimulus that triggers fear – for example, first a soft sound, then a loud, frightening noise. After conditioning, the presentation of the neutral stimulus alone triggers fear.
-
- Glossary
GABA
GABA is an amino acid and the most important inhibitory neurotransmitter, which acts as a messenger in the transmission of information between neurons at their synapses.
-
- Glossary
Ganglion cell
The ganglion cell bundles the signals from the photoreceptors in the retina and transmits them via its axons (long, fiber-like extensions of a nerve cell. All of these axons together form the optic nerve.
-
- Glossary
Ganglion
Term for a cluster of nerve cell bodies in the peripheral nervous system. The term nerve node is often used because of its appearance. (Greek gágglion = knot-like)
