CH 4 - Neurons and the Brain Flashcards
How many watts does the brain have?
13 watts
Is the brain embodied?
Yes it is part of the body
How many brain regions are there per hemisphere?
180
How many neurons are there
86 Billion
How many km of nerve fibers?
> 750.000 km
How much does the brain weigh?
1.4 kg
What is the nervous system?
An organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs.
Which two subsystems of the nervous system exist in vertebrates?
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
What does the CNS do?
central information processing system formed by the brain and the spinal cord. It collects and distributes data throughout the body.
What does the PNS do?
transmits signals between sensory organs, muscles and internal organs and the CNS.
Cerebrum
The cerebrum (Großhirn) is the largest and uppermost portion of the brain and accounts for sensory integration, voluntary motion and higher-level cognitive functions.
It is split into two hemispheres that are
connected by the corpus callosum (Balken).
The cerebral cortex (Großhirnrinde), also
called the gray matter (graue Substanz), is
the folded outer layer of the cerebrum that
is mainly comprised of cell bodies.
The inner part of the cerebrum, the white
matter (weiße Substanz), is a core of nerve
fibers that connect the cortical regions.
By what are the two hemispheres of the brain connected by?
The corpus callosum
Cerebral cortex
Cortex is Latin for “bark,” and describes the outer gray matter covering of the cerebrum. The cortex has a large surface area due to its folds, and comprises about half of the brain’s weight.
The right hemisphere controls the left side of the body, and the left half controls the right side of the body. The two halves communicate with one another through a large, C-shaped structure of white matter and nerve pathways called the corpus callosum. The corpus callosum is in the center of the cerebrum.
Difference between white and grey matter
Gray and white matter are two different regions of the central nervous system. In the brain, gray matter refers to the darker, outer portion, while white matter describes the lighter, inner section underneath. The white matter is a core of nerve fibers that connect the cortical regions
Three anatomical features of the surface of the cerebral cortex
It is covered with ridges (gyri) and folds (sulci). On each hemisphere two sulci divide the cerebral surface into a frontal, parietal, temporal and occipital lobe
occipital lobe
The occipital lobes sit at the back of the head and are responsible for visual perception, including colour, form and motion
draw the brain
draw
What does the brainstem do?
Connects the cerebrum with the spinal cord
Which sections is the brainstem divided into?
- Diencephalon
- Midbrain
- Pons
- Medulla Oblongata
Which four sub-structures is the Diencephalon divided into?
- Epithalamus (production of melatonin)
- Thalamus (relay and distribution of sensory and motor signals to different regions of the cerebral cortex)
- Hypothalamus (control of autonomic functions like temperature and appetite, behavior and hormone production)
- Subthalamus
What is the autonomic nervous system = peripheral nervous system?
responsible for homeostasis (self-regulation) and operates largely unconsciously.
What are the two antagonist subsystems of the autonomic nervous system?
Sympathetic nervous system & parasympathetic nervous system
What does the sympathetic nervous system do?
connection of the internal organs to the brain; preparation of the organism for stress (increase of heart rate, blood fow, sweating)
What does the parasympatic nervous system do?
mainly cranial nerves (Hirnnerven) and lumbar (lenden) spinal nerves
- sets the body to resting state and increases digestive functions
Is connectivity static and dynamic?
Yes. It is static in anatomical connectivity and dynamic in functional connectivity, dependent on the current cognitive task.
What can brain networks (topology) be analyzed with?
Graph theory
What are brain networks related to?
Integrated information theory (IIT) attempts to provide a framework capable of explaining why some physical systems (such as human brains) are conscious
Is there cognition without the brain?
Yes (sort of). Jellyfish have a diffuse nervous system.
Then there is the endocrine system (Hormonsystem) that is also present in humans that is a regulatory system that works in parallel to the nervous system by secreting hormones.
Mythos about the brain
Only ten percent of the brain are used
Every part of the brain is used but not all parts are used at once (which would result in epilepsy).
The brain does not produce new neurons in adults
In certain brain areas, new neurons are produced throughout life.
The size of the brain is related to intelligence The brains of elephants and whales are much larger than those of humans
A mapping of the nervous system
What is cognition connected to?
- Brain
- Sensory Organs (perception)
- Spinal Cord and Muscles (action)
-> draw slide 21
A mapping of the nervous system
Function of the brain
Cognition connects to anticipation.
Anticipation leads to assimilation.
Assimilation leads to adaptation.
Adaptation connects to cognition.
assimilation
the process of taking in and fully understanding information or ideas
How can the mapping between cognitive functions and brain regions (lobes) be determined?
With functional brain imaging
Frontal lobe
short-term memory, action planning, movement control
Parietal lobe
somatic sensation, body image (connection of senses to the extremities)
occipital lobe
vision
temporal lobe
hearing, learning, memory, emotion
The neocortex in the cerebral cortex is the center of
higher cognitive functions and intelligence
6 parts of the neocortex
Layer I: Molecular Layer
- Dendrites of the cells located in deeper layers and axons that travel through this layer in other areas of the cortex
Layer II: External Granular Cell Layer
- Small pyramidal-shaped cells. Projections to other cells within the same and to other cortical areas.
Layer III: External Pyramidal Cell Layer
- similar to II. Neurons located deeper in the layer and lager.
Layer IV: Internal Granule Cell Layer
- large number of small spherical neurons.
- main recipient of sensory input from the thalamus
Layer V: Internal Pyramidal Cell Layer
- pyramidal cells even larger than those in layer III.
- major output pathway of the cortex
Layer VI: Multiform Layer
- layer with heterogeneous neurons which blends into the white matter.
-> Draw picture
What structure exists in the cortex in addition to the laminar structure?
Columns. Cortical Microcircuits.
What is the minicolumn?
The most basic building block is the minicolumn. It consists out of 80-100 neurons.
What are cortical columns comprised of?
Many minicolumns
