Chapter Two Flashcards
Myelin:
fatty substance deposits that surround an axon of some cells (mostly motor)
blocks the Na/K exchange allowing the signal to jump to the Nodes of Ranvier
Destruction of myelin is found in a number of pathologies, most notably…
multiple sclerosis
Briefly summarize how inhibitory (GABA) neurons function:
makes the inside more negative than normal and harder to depolarize
etc: chloride channels
What are the differences between these two groups:
- serotonin, dopamine, acetylcholine
- GABA and glutamate
modulatory which can have bodily effects; their cell bodies are localized but their axonal projections spread diffusely
GABA and glutamate have their cell bodies distributed throughout the brain
Explain the process of AP:
- Passive currents collectively carry the strength to reach a threshold and Na+ channels begin to open
- Na+ enters the cell and the negative potential inside is reduced (depolarization)
- Cell membrane is completely permeable and momentarily reverses.
- Negative potential of the cell is restored via the outward flow of K+. Na+ closes.
- Hyperpolarization occurs, preventing AP from traveling backward.
How does myelin allow an AP to propagate faster?
This blocks the Na/K transfer and the AP jumps via passive conduction
What are some biological functions that can have a high spiking rate? Low?
High: speech
Low: vision
The function of a brain region is determined by its…
Neurons responding to similar types of information tend to…
neuronal inputs and outputs
be grouped together
Gray matter consists of […].
White matter consists of […].
neuronal cell bodies; axons and support/glia cells
Association tracts: []
Commissures: []
Projection tracts: []
WM tracts project between different cortical regions of the same hemisphere
WM tracts project between different cortical regions in different hemispheres
WM tracts project between cortical and subcortical structures
Ventricles:
hollow chambers filled with CSF carries waste, transfers messenger signals, protective cushion
Raised folds of the cortex [].
Buried grooves of the cortex [].
Gyri
Sulci
What are the three types of densities?
- neocortex
- mesocortex
- allocortex
What structural component divides the frontal and temporal lobes?
Sylvian fissure
What is the island cortex of the brain? Where is it located?
insula; located buried underneath the temporal lobe
Action Potential
A sudden change in the electrical properties of the neuron membrane in an axon, which forms the basis for how neurons code information (in the form of the rate and synchrony of AP; temporal and summation)
Electrical currents are actively transmitted though …
Electrical currents flow passively through …
Passive currents will initiate AP if …
axons by an action potential
dendrites and soma of neurons
their summed potential is strong
enough at the start of the
axon (called the hillock)
What is the most important commissure?
corpus callosum
What structures does the hindbrain consist of?
cerebellum
pons
medulla oblongata
What does the midbrain consist of?
substantia nigra
superior and inferior colliculi
What does the diencephalon consist of?
thalamus
hypothalamus
mamillary bodies
What does the forebrain consist of?
cerebrum (telencephalon)
dencephalon
What does the telencephalon consist of?
basal ganglia
limbic system
cerebral cortex
What do the basal ganglia consist of?
What are the basal ganglia?
caudate nucleus
putamen
globius pallidus
subcortical gray matter involved in aspects of motor control, skill learning and reward learning
What does the limbic system consist of?
What is the limbic system?
cingulate cortex
hippocampus
amygdala
subcortex involved in relating the organism to its present and past environment
What does the cerebral cortex consist of?
frontal cortex
temporal cortex
parietal cortex
occipital cortex
What are the four different ways in which regions of the cerebral cortex may be divided hence labeled:
- Pattern of gyri and sulci: same pattern found on everyone (different shapes and sizes)
- Cytoarchitecture: Brodmann’s areas
- Function: only for primary visual and motor cortex; higher cortical regions are harder to ascribe unique functions to
- Connectivity: different regions have different connectivity profile; connect to some regions strongly and others weakly; MRI techniques can be used to segment individual brains with this information
Brodmann’s areas:
regions of cortex defined by the relative distribution of cell types across cortical layers (cytoarchitecture)
The amygdala has been implicated in the detection of […].
Parts of the cingulate gyrus have been implicated in the detection of […].
Hippocampus is particularly important for […].
fearful or threatening stimuli
emotional and cognitive conflicts
learning and memory
Thalamus:
major subcortical relay center
processing station between all sensory organs (except small) and the cortex
Hypothalamus:
consists of a variety of nuclei that are specialized for different functions that are primarily concerned with the body and its regulation
EX: body temperature, hunger/thirst, sexual activity, endocrine functions
Tumors of the hypothalamus result in…
eating and drinking disorders, precocious puberty, dwarfism, and gigantism
Superior colliculi:
Inferior colliculi:
midbrain nucleus that forms part of a subcortical sensory pathway (integrates information from several senses)
midbrain nucleus that forms a part of a subcortical auditory pathway
Cerebellum:
structure attached to the hindbrain
important for refined motor movements
Unilateral lesions to the cerebellum result in…
Bilateral lesions result in …
poor coordination on the same side of the body as the lesion (ipsilesional side)
abnormal gait, dysarthria, nystagmus
Pons:
part of the hindbrain
key link between the cerebellum and the cerebrum
retrieves visual system information to control eye and body movements
Medulla oblongata:
part of the hindbrain
regulates vital functions
EX: breathing, swallowing, heart rate, wake-sleep cycle
