Unit 2-Introducing the Brain Flashcards
What is a neuron? What are its three main components?
A cell type that makes up the nervous system and supports cognitive functions
Soma (cell body), dendrites, and axon
What does the cell body (soma) contain?
The nucleus, which contains genetic code and is involved in protein synthesis
Other organelles
What are dendrites?
Branching structures that extend away from the cell body to receive information from other neurons in close proximity
What is the axon?
Long tail of neuron that is used to propagate action potentials that send information to nearby neurons
How many dendrites and how many axons does a neuron have?
One axon, many dendrites
What is a synapse? What is it formed by?
A small gap between neurons that permits signalling
The presynaptic and postsynaptic neurons
What is an action potential? When is the action potential propagated in the axon? What happens when the action potential reaches the axon terminal?
A sudden change in the electric properties of the axon membrane, which forms the basis for how neurons code information
When the presynaptic neuron is active
Neurotransmitters are released
What are neurotransmitters? What do they bind to on the postsynaptic neuron? What is their impact on the postsynaptic neuron?
Chemical signals released by one neuron that affect other neurons
Receptors on the dendrites or cell body
Create synaptic potential
What is synaptic potential? How is it conducted? When does it cause an actional potential?
A change in a neuron’s membrane potential due to the binding of neurotransmitters released from another neuron
Passively, without creating action potential
When the sum of passive currents increases above a certain threshold in the axon hillock
What is the axon hillock?
The region of the neuron’s cell body where the axon begins and where the sum of passive currents is calculated to initiate an action potential
What are the five phases in action potential?
Resting
Depolarisation
Repolarisation
Hyperpolarization
Refractory Period
What happens during the Depolarisation phase? What type of ions rush into the neuron to make the inside more positive? What gate is opened to allow for this?
A sufficiently strong stimulus causes the membrane potential to increase
Sodium ions
Sodium gates
What is the resting membrane potential in the Resting phase?
Around -70 millivolts
What happens during the repolarization phase? What type of channels open up and what type of channels close? What does this cause? At around what potential does this happen?
The negative charge is restored
Potassium channels open and sodium channels close
Potassium ions leaving and sodium ions no longer entering the neuron
-50 mV
What happens during the refractory period phase?
The neuron is temporarily unable to fire another action potential due to the inactivation of voltage-gated ion channels
What happens during the hyperpolarization phase? What is the purpose of this?
The membrane potential briefly becomes more negative than the resting potential before returning to its resting state
Preventing the action potential from travelling backwards
What is myelin? What is another function of it?
A fatty substance around axons that speeds conduction
Blocking sodium and potassium transfer in normal conditions
What are the three types of effects of neurotransmitters? Explain all of them. Give some examples of neurotransmitters causing each of them:
Inhibitory - making the neuron less likely to fire (e.g., GABA)
Exhibitory - making the neuron more likely to fire (e.g., glutamate)
Modulatory functions (e.g., serotonin, dopamine)
What is the primary way through which neurons code information?
Through their spiking rate, i.e., the number of action potentials is propagated per second
How can one determine the type of information coded by a neuron?
By the inputs and outputs of the neurons, i.e., where the information comes from and where it goes
What does grey matter primarily consist of?
Neuronal cell bodies
What does white matter primarily consist of?
Axons and glia
What are glia?
Support cells involved in forming myelin and repairing tissues
What is the cerebral cortex? What type of matter does it consist of? What comes under it? What comes under this?
The outermost layer of the brain
Grey matter
White matter fibres
Subcortex
What is the function of white matter tracts? What are the three kinds of white matter tracts?
They connect different regions of the brain to each other
Association tracts, commissures, and projection tracts
What is the subcortex made up of?
Grey matter
What is the hierarchical view of the central nervous system?
Older structures are not replaced with newer ones
Newer structures are added onto older ones
Older pathways still contribute to brain functionality
What is a ventricle?
A hollow chamber in the brain containing cerebrospinal fluid (CSF)
What do association tracts connect? How about commissures? How about projection tracts?
Cortical regions within the same hemisphere
Cortical regions in different hemispheres
Cortical and subcortical structures
What is cerebrospinal fluid? What are its three primary functions?
A fluid filling the ventricles in the brain
Carries waste, transfer messenger signals (hormones) and provides cushioning for the brain
What are the four ventricles of the brain?
The left lateral ventricle, right lateral ventricle, central ventricle and brainstem/hindbrain ventricle
What do the terms anterior/rostral and posterior/caudal refer to?
Anterior/rostral refers to the front of the brain
Posterior/caudal refers to the back of the brain
What do the terms superior/dorsal and inferior/ventral refer to?
Superior/dorsal refers to the top of the brain
Inferior/ventral refers to the bottom of the brain
What do the terms lateral and medial refer to?
Lateral refers to the outer surface of the brain
Medial refers to the inner part of the brain
What is a sagittal slice?
A vertical slice that divides one of the brain’s hemispheres into two
What is a coronal slice?
A vertical slice that divides the brain into front and back parts (from ear to ear)
What is a midline slice?
A midline slice is a vertical slice dividing the brain into the two hemispheres
What is an axial slice?
A horizontal slice that divides the brain into upper and lower parts
What are gyri?
The ridges or folds on the surface of the cerebral cortex
What are sulci?
The grooves or furrows that separate gyri
What does the cerebral cortex consist of? Why is it structured with gyri and sulci?
Two folded sheets of grey matter organised into two hemispheres
To create a higher surface area
What are the three layers of the cerebral cortex?
The neocortex, mesocortex, and allocortex
What is the neocortex? What is it involved in?
The largest part of the cerebral cortex in humans and other mammals
Higher-order brain functions
What is the mesocortex? What are its primary functions?
A transitional region of the cerebral cortex bridging the neocortex and allocortex
Emotional processing, autonomic functions, and awareness of bodily sensations
What are the four main ways in which the regions of the cerebral cortex can be divided by?
By the pattern of gyri and sulci
By Brodmann’s areas
By function (e.g., by sensory vs motor)
By connectivity profiles (which brain regions are connected to what region)
What is the allocortex? What are the primary structures that it includes? What are its most crucial functions?
The evolutionarily older part of the cerebral cortex
The primary olfactory cortex and the hippocampus
Smell and memory formation
What are the four lobes of the lateral surface of the cortex?
The frontal, parietal, temporal and occipital
What are Brodmann’s areas?
Divide the cortex into approximately 52 areas based on relative distributions of cell types
What are the three primary systems in the subcortex?
The basal ganglia
The limbic system
The diencephalon
What is the primary function of the thalamus?
A sensory relay for all senses except smell
What is the limbic system’s primary function? What are its primary components, and what is the function of each?
The detection and expression of emotional responses
The Amygdala (fear, threatening stimuli) Cingulate Gyrus (emotional and cognitive conflicts), Hippocampus (learning and memory), Mammillary bodies (memory), Olfactory Bulbs (smelling)
What is the basal ganglia? Where are they located in the brain? What are their two primary functions?
Two large rounded masses, one in each hemisphere
In the centre of the brain, around the thalamus
Regulating motor activity, Learning of rewards, skills and habits
What two structures does the diencephalon consist of?
The thalamus and hypothalamus
What are the two main components of the midbrain?
Superior and inferior colliculi
What is the primary function of the hypothalamus?
Deals with homeostasis, i.e., temperature, hunger, thirst, sexual activity, body, growth, etc.
What are the two primary functions of the superior colliculi?
Integrating information from several senses
Programming fast eye movements
What is the primary function of the inferior colliculi?
Auditory processing
What is the implication of the midbrain and hindbrain providing older pathways for some senses?
Allow for reflex actions to certain stimuli
What are the two main functions of the cerebellum?
Ensuring smooth execution of movement
Integrating motor commands with sensory feedback
What are the three main components of the hindbrain?
The cerebellum, pons, and medulla oblongata
What is the function of the pons?
Connecting the cerebellum and cerebrum, in the forebrain, and responsible for higher cognitive functions such as thinking, perception, planning, and voluntary movement
What is the primary function of the medulla oblongata?
Regulating vital functions such as breathing, swallowing, heart rate, and the wake-sleep cycle
