Cognitive Neuroscience Flashcards
What is cognitive neuroscience?
It is the scientific study of biological substrates underlying cognition, with a specific focus on the neural substrates of mental processes
Where does visual info from our environment come in through?
Visual info from our environment comes in through the pupil goes through the lens
What do photoreceptor cells do?
They convert the visual info from the environment into electrochemical energy that the brain can then process
What does the lens do?
The lens focuses the visual info on the back of your eye
Where are photoreceptors located?
on the back of the eye
Where are there no photoreceptors?
On the optic nerve
Why are there no photoreceptors on the optic nerve?
There are no photoreceptors because the photoreceptor cells have axons which take the info from photoreceptor cells up to the brain to be processed. These axons gather to make up the optic nerve
What does the nervous system do?
They coordinate our actions and sensory information by transmitting signals to and from different parts of the body
What does the nervous system detect?
It detects environmental changes that will impact the body and respond to these events
What does the nervous system regulate?
It regulates the internal functions and produces motor actions
What are genes?
They are molecules of DNA that carry info on how to build bodies
What are cells?
Cells are basic units of structure and function of all living things
What are tissues?
Tissues are groups of cells of the same kind
What are organs?
Organs are structures composed of one or more types of tissues which work together to perform a specific function
What are systems?
Systems are groups of organs that work together to perform a certain function
Why is the structure of a living cell important?
It is important to understand the structure of the living cell because if the cell is damaged, this can produce changes in behaviour and cognition
What is the membrane?
The membrane is a thin semi-permeable membrane that surrounds the cell
What are the two functions of the membrane?
The membrane protects the integrity of the interior of the cell e.g. allows certain substances inside the cell but keeps others outside
It also helps support the cell and maintain it’s shape
What does the nucleus contain?
The nucleus contains the cells genes and controls the cells growth and reproduction
What does the nucleolus do and where can it be found?
The nucleolus contains chromosomes and is within the nucleus
Where are channels found?
Channels are found on the membrane of the cell
What are channels made of?
Channels are made of proteins
What do channels do?
Channels allow the exchange of various materials in and out of the cell
What does the mitochondria do?
The mitochondria converts nutrients into ATP for chemical energy
What is ATP?
ATP is a complex organic chemical that provides energy to drive many processes within the cell
What are the two main types of cell in the nervous system?
Neurons and glia cells
What are neurons thought to be?
Neurons are thought to be building blocks of the nervous system
What do neurons do?
Neurons communicate with one another to perform information processing tasks
What are the different types of glia cells?
Astrocytes, Schwann cells and oligodendrocytes
What do the different types of glia cells do?
Different types of glia cells provide support to the neurons within the nervous system
What do oligodendrocytes do?
They provide the myelin sheath around the axon of the neurons in the central nervous system
What does the insulation formed by the myelin sheath allow?
It allows the communication along the cell to be much faster and more efficient
What do Schwann cells do?
They form the myelin sheath around the axons in the peripheral nervous system
What do astrocytes do?
Astrocytes provide nutrients to the neurons and help the cell to maintain their extracellular environment. They also provide structural support
Where is the nucleus of a neuron found?
It is found within the cell body or soma
What happens at the cell body of a neuron?
Coordination of the info processing tasks are said to take place at the cell body. It is also important for keeping the cell alive
Where are dendrites of a neuron found?
Dendrites are found surrounding the cell body
What do dendrites do?
They receive info from other neurons and relay it to the cell body
Cells tend to only have one axon. What does it do?
This axon transmits info to other neurons from this neuron
What happens at the axon hillock?
The axon hillock is where inputs from other cells are summated before being transmitted along the axon of the cell
What is the myelin sheath formed by?
The myelin sheath is formed by glial cells
What is myelin sheath?
Myelin sheath is the fatty layer of insulation which surrounds the axon of the neuron
What are the nodes of Ranvier?
They are the little gaps in the myelin sheath
What do the nodes of Ranvier do?
They allow the electrical signals to jump across the myelin sheath, making communication quicker
Where are the axon terminals found?
Axon terminals are found at the end of an axon
What happens at the axon terminals?
This is where axons will form synapses with the dendrites of other neurons
How do neurons communicate?
Neurons communicate using electrochemical signals
What’s the difference between the signals within the cell itself and the communication across the synapse?
The signals within the cell itself is thought to be electrical in nature whereas the communication across the synapse is thought to be chemical in nature
What do dendrites form synapses with?
Dendrites form synapses with other presynaptic cells
What happens if the cell receives enough stimulation from enough presynaptic cells?
It will reach a threshold and will fire and send an electrical impulse called an action potential along the cell
What is an action potential?
It is an electric signal that is conducted along the length of a neuron’s axon to the synapse
What is spatial summation?
Spatial summation refers to the stimulation of several spatially separated neurons at the same time
When does the communication between cells change?
When a cell sends an action potential along its axon, it comes down to the bottom of the cell where it synapses with a neighbouring cell, and its here where the communication changes and it becomes a chemical signal rather than electrical
What is present in presynaptic cells that if stimulated enough gets released into the synapse?
Chemicals or neurotransmitters
What do neurotransmitters do one it crosses the synapse?
It will attach itself to receptors in the dendrites of the post-synaptic cell
What is specific about neurotransmitters?
They only attach to certain receptors e.g. lock and key
What is temporal summation?
Temporal summation is when there’s an input from one cell, but that input occurs repeatedly
Why do neurons fire?
Neurons fire to allow us to carry out specific functions
What are ions?
They are charged atoms
What is an electric potential?
An electric potential is an overall difference in charge between nearby areas
(negative ions are attracted to the are where the more positively charged ions are)
In an action potential why do particles diffuse?
They diffuse to equate concentration across space
How can positive ions cross the cell membrane
They can cross via ion channels
What is the resting potential of a cell?
It is the difference in electric charge between the inside and outside of the cell. The resting potential is -70mv
What is the sodium potassium pump?
It is a protein pump that is continually moving three sodium ions outside of the cell and two potassium ions inside the cell
Looking at the sodium potassium pump, what happens when the cell is stimulated by either spacial or temporal summation?
The cell reaches a threshold and so there is a rush of sodium ions inside the cell
Looking at the sodium potassium pump, what happens to the cell when there is an influx of sodium ions in the cell?
The cell becomes more positively charged inside rather than on the outside, reaching its max of 40mv
Looking at the sodium potassium pump, when the cell becomes more positively charged on the inside what happens?
The sodium ion channels close again and the potassium ion channels will open. The potassium crosses the channel to the more negatively charged outside of the cell restoring the charges back to the original
Looking at the sodium potassium pump, once the charges have been restored inside and outside of the cell, what happens?
The membrane potential lower and we have repolarization in which the inside of the cell is more negatively charged than outside
What is hyperpolarization and when does it take place?
Hyperpolarization is where the inside of the cell becomes even more negatively charged, and it takes place when the cell overcompensates
Looking at the sodium potassium pump, how do the neurons return to its resting state?
The sodium potassium pump moves three sodium ions outside the cell and two potassium ions inside the cell
What is saltatory conduction?
It is the propagation of action potentials along the myelinated axons from one node of Ranvier to the next node
What happens if saltatory conduction is disrupted?
If disrupted it can cause damage
e.g. multiple sclerosis
What is multiple sclerosis?
It is an autoimmune disease in which one’s own immune system damages the myelin sheath
What are the three main types of neuron?
Motor, sensory and inter
What are motor neurons?
Motor neurons are the neurons that carry signals from the spinal cord to the muscles
What do motor neurons produce?
They produce a movement
What do motor neurons synapse with?
They synapse with muscle fibres
What do motor neurons release and what does this result in?
They release a neurotransmitter into its synapse and this causes the muscle fibre to contract and a movement is produces
What happens to motor neurons in motor neuron disease?
The motor neurons will degenerate and die leading to weakness, paralysis and eventually death
What are sensory neurons?
Sensory neurons are neurons that receive information from the external world and convey this information to the brain via the spinal cord
What do sensory neurons have?
They have specialised endings on their dendrites that receive signals for light, sound, touch, taste and smell
In the surface of our skin when our nerve endings or dendrites with channels are activated what happens?
The nerve endings or dendrites with channels are mechanically activated to change the potential in the cell and transmit a message to the brain
What are interneurons?
They carry information from sensory neurons to the nervous systems and some will carry info form the nervous system to motor neurons
What is a synaptic transmission?
It is a communication between neurons that is chemical in nature
In synaptic transmission, when an axon potential comes along the axon to the terminal buttons what happens?
The voltage gated calcium ion channels will open and calcium can rush into the cell
In synaptic transmission, what happens once the the voltage gated calcium ion channels open?
It encourages the vesicles in the terminal buttons (contain neurotransmitters) to be released into the synapse
In synaptic transmission, what is on the dendrites? and what does it allow?
On the dendrites we have these ligand-gated ion channels, essentially receptors, and so certain neurotransmitters can then attach to the receptors.
When neurotransmitters attach onto the receptors, what does this cause?
This will then cause a postsynaptic potential in the post synapse because the ion channels will then open when the neurotransmitters attach to them, leading to a full voltage change in the post synaptic cell
To stop the presynaptic cell stimulating the postsynaptic cell indefinitely, what is done?
Once the neurotransmitter is released into the synapse and attaches to the receptor, almost immediately there are reuptake channels which start the flow of the neurotransmitter backwards
To stop the presynaptic cell stimulating the postsynaptic cell indefinitely, on top of the reuptake channels, what else is done?
There is also enzyme deactivation and so proteins will deactivate the neurotransmitter to stop the activity on the postsynaptic cell
On top of the reuptake channels and enzyme deactivation what else can be done to stop the presynaptic cell stimulating the postsynaptic cell indefinitely?
There is also auto receptors on the postsynaptic cell which will start inhibiting the release of the neurotransmitter back into the vesicles and encouraging the reuptake of the neurotransmitter back into the vesicles
What does the postsynaptic cell receive?
It receives both excitatory signals but also inhibitory signals
On the basis of spatial summation what will the excitatory neurotransmitter produce?
It will produce depolarization of the postsynaptic cell, this is when the sodium rushes into the cell and becomes positively charged in the inside
On the basis of spatial summation what will an inhibitory neurotransmitter produce?
It will cause hyperpolarization which mitigates the effects of an excitatory neurotransmitter
What do excitatory synapses do?
Excitatory synapses will raise the potential in the cell, it will open the channels allowing the sodium ions to enter the cell.
What do inhibitory synapses do?
Inhibitory synapses will reduce the potential in the cell by potentially causing positive ions to leave the cell
What is the most common excitatory neurotransmitter in the brain?
Glutamate (Glu)
What is glutamate important for?
It is important for learning and memory and increases the likelihood that an action potential will occur and a cell will fire
In the hippocampus what neurotransmitter is released into the synapse?
Glutamate
What happens if too much of the neurotransmitter is released into the synapse?
This can lead to over excitation resulting in seizures and migraines
What disease can be brought about if someone has too much glutamate?
OCD
What is the most common inhibitory neurotransmitter in the brain?
GABA
What does GABA do?
It counteracts the effects of glutamate and regulates and prevents over-excitation
What can a GABA deficiency result in?
It can result in seizures, tremors, insomnia and an increased responsiveness to stress
What does acetylcholine do?
It regulates motor control and is important in attention, learning, memory, arousal etc.
What type of signals does acetylcholine send?
It sends excitatory signals in synapses between neurons and skeletal muscles
It sends inhibitory signals in synapses between neurons and the heart
What happens if we have too high or too low levels of acetylcholine in our brains?
Too high - can result in depression
Too low - linked with Alzheimer’s Disease and is associated with the degeneration of cholinergic neurons
What is Alzheimer’s Disease? (AD)
Most common form of dementia
When can a definitive diagnosis of AD be made?
Post-mortem exam which shows a build up of plaques and tangles in the brain
What are plaques?
Plaques are collections of amyloid proteins that are found between the neurons
What are tangles?
Tangles are insoluble twisted fibres inside neurons, formed mainly from protein called tau
How does dopamine know whether to present an excitatory or inhibitory signal?
It depends on the receptors in the post-synaptic cell that dopamine is attaching to
What does dopamine play an important role in?
It plays an important role in movement, motivation, pleasure and emotional arousal
What is too much or too little of dopamine linked to?
Too much - linked to schizophrenia
Too little - linked to tremors, difficulty initiating and stopping movement
What does Parkinson’s disease result from?
Results from degeneration of dopamine producing cells
Where is dopamine found?
In the brain
What does serotonin do?
It regulates mood, appetite and sleep
What is serotonin involved in?
It is involved in cognitive functions like learning and memory as well as arousal and aggression
What does norepinephrine regulate?
It regulates mood and arousal
e.g. vigilance to danger
What is Prozac?
Prozac is described as a selective serotonin reuptake inhibitor
Why is Prozac described as a selective serotonin reuptake inhibitor ?
Someone with depression may not have enough serotonin and so Prozac prevents the reuptake of serotonin so it stays in the synapse for longer and is able to stimulate the posts-synaptic cell
What is an agonist drug?
These drugs mimic or increase the effect of the neurotransmitter
What is antagonist drug?
These drugs block or decrease the effect of a neurotransmitter
When are agonists important?
Important if we don’t have enough of a certain neurotransmitter
When are antagonists important?
Important if we have too much of a certain transmitter
What does cocaine do?
It is an agonist - it blocks dopamine, norepinephrine and serotonin uptake
What does L-dopa do?
It is a common treatment for Parkinson’s Disease
It increases the production of dopamine in the neuron
What are the three ways in which agonists work?
- They either work by blocking the reuptake of the neurotransmitter but other drugs can increase the production of a neurotransmitter
- They also work by increasing the amount of the neurotransmitter that’s released from the vesicles into the synapse
- They also work by binding and activating the postsynaptic receptors
Amphetamine is an agonist. What does amphetamine do?
Amphetamine stimulates the release of dopamine and norepinephrine releasing it into the synapse so that the postsynaptic cell can be stimulated more
Nicotine is an agonist. What does nicotine do?
Nicotine will activate the acetylcholine receptors in the postsynaptic cell
Cannabis is an agonist. What does cannabis do?
It activates the CB1 cannabinoid receptors in the postsynaptic cell through the neurotransmitter anandamide
Botox is an antagonist. What does Botox do?
It prevents the release of neurotransmitters into the synapse
Haloperidol is an antagonist. What does it do?
It binds to the postsynaptic receptors and blocks them, preventing dopamine from activating receptors by blocking them.
(it is used to treat schizophrenia)
What is the nervous system split into?
Peripheral and Central Nervous System
What is the peripheral nervous system split into?
It is split into the autonomic and somatic nervous system
What is the central nervous system split into?
It is split into the brain and spinal cord
What does the somatic nervous system control?
It controls the skeletal muscles which attach to bones by tendons
What does the somatic nervous system enables us to do?
It enables us to move around and convey info in and out the central nervous system
What does the autonomic nervous system regulates?
It regulates internal functions
What does the autonomic nervous system carry?
It carries involuntary and automatic commands that control blood vessels, organs and glands
What does the autonomic nervous system split into?
Sympathetic and parasympathetic
What is the sympathetic nervous system in charge of?
It’s in charge of increasing our arousal enabling us to get ready for action
What does the parasympathetic nervous system do?
It counters effects of sympathetic nervous system and means we don’t get too excited when we don’t need to
What does the peripheral nervous system consist of?
It consists of nerves
What does the somatic nervous system carry?
It carries nerves to muscles where they form synapses allowing us to move
What does the autonomic nervous system regulates?
It regulates internal functions and enable us to prepare our body for action or calming down
How do the sympathetic and parasympathetic system act?
They act in a coordinated manner
Where is the spinal cord housed?
It is housed within the spinal column
What is the spinal column?
It is a column of small bones called vertebrae
How does info come into the spinal cord and what does it conduct?
Info comes in the spinal cord along the dorsal nerve so it conducts sensory info from outside the body
What is a dorsal root ganglion?
It contains all the neurons that then have axons that go into the dorsal horn of the spinal cord where sensory info is conveyed to the brain
What is the vental horn?
It is where cell bodies for motor activity are
What do vental horns do?
They convey commands to the skeletal muscles to carry out movements
Spinal cord has two dorsal nerves. What does the left and right dorsal nerve do?
The left dorsal nerve brings sensory info from left side of the body and vice versa
Spinal cord has two ventral nerves. What does the left and right ventral nerves do?
The left ventral nerve sends motor signals to the left side of the body and vice versa
What is the hindbrain formed of?
It is formed with the pons, medulla, reticular formation and cerebellum
What does the hindbrain do?
It coordinates information flow to and from the spinal cord
What is the medulla and what it’s role?
It is an extension of the spinal cord and it’s role is in controlling our heartrate, circulation and respiration
What is reticular formation and what does it regulate?
It is a network of neurons that regulate arousal, so they coordinate the sympathetic and parasympathetic nervous systems and control our sleep and wake cycles
What does the cerebellum do?
It plays an important role in controlling our fine motor activity
What do pons do?
They relay info from cerebellum to the rest of the brain
What can the midbrain be split into?
It can be split into the Tegmentum and Tectum
What does the midbrain coordinate?
It coordinates basic functions related to perception and action
What is the tectum?
Tectum is important for spatial orienting to the environment
What can the tectum be divided into?
Superior and inferior colliculi
What does the superior colliculi play a role in?
It plays a role in orienting to visual information
What does the inferior colliculi do?
It’s important for orienting to auditory information
What does the tegmentum do?
It is important for movement, arousal and pleasure seeking
What is the substantia nigra?
It is part of the tegmentum with high levels of dopamine, giving it its dark colour
What is the forebrain formed of?
It is formed with the cortex and sub-cortical structures
What does the forebrain do?
It controls our complex cognitive, emotional, sensory and motor functions
What does the basal ganglia do?
Basal ganglion plans initiation of intentional movements
What does the thalamus do?
Thalamus relays and filters info from the senses to the cortex
What does the limbic system do?
Limbic system is important for regulating our emotions
What does the hypothalamus do?
Hypothalamus regulates internal body functions and so is important for temperature, hunger and 4F’s
What does the pituitary gland do?
Pituitary Gland controls the release of hormones to glands
What does the hippocampus do?
Hippocampus creates and integrates new memories but is not a long-term storage
What does the amygdala do?
Amygdala is used for emotional processing and memory, and in particular processing and memory of fear
In the cortex, what is it called where the gray matter folds in?
Sulcus or plural sulci
In the cortex, what is it called where the folds and bumps are on the outside?
Gyrus or plural gyri
What is the corpus callosum?
It is a bridge of white matter that connect the left and right hemispheres
What does the corpus callosum do?
It allows the left and right hemispheres to communicate with one another
Each hemisphere is split into 4 lobes. What are they?
Frontal, parietal, occipital and temporal
What do bones in our skull protect?
They protect the brain from damage as a result of external forces
What does CSF in the brain do?
Protects the brain by working as a shock absorber
We have 3 membranes in the skull that also protect the brain. What are they?
Durameter, Piamater, Arachnoid and Subarachnoid space
What does the choroid plexus do?
It creates and excretes CSF
What does the occipital lobe do?
It plays an important role in our vision
What does the temporal lobe do?
It plays an important role in our semantic knowledge, word meanings, object identification and processing auditory info
What does the parietal lobe do?
It plays an important role in our spatial attention, sensory integration, object location and our ability to process numbers and quantities
What does the frontal lobe do?
It plays an important role in our planning, our executive control and our abstract thinking
