Week Two Flashcards
Central Nervous System, The Brain, and EEG
What are the two major systems of the nervous system?
The central nervous system (CNS)
The peripheral nervous system (PNS)
What does the CNS consist of?
Cerebrum (the brain)
Brain stem
Cerebellum
Spinal cord
What does the PNS consist of?
All the remaining nerves outside the CNS
How many pairs of spinal and cranial nerves are in the PNS?
Spinal nerves: 31 pairs
Facial nerves: 12 pairs
What is the main function of the PNS?
Connects the brain (CNS) to the outside world
What is a neuron?
The fundamental unit of the nervous system
What is the function of a neuron?
Specialized cells that transmit information throughout the body in the form of electrical and chemical signals
Critical for communication between different parts of the body and the brain
What are the major parts of a neuron? (7)
Dendrites
Soma/cell body
Axon
Myelin sheath
Nodes of Ranvier
Axon terminal
Synapse
Explain the role of the dendrites
Collect signals from neighbouring cell and pass to the cell body if the signals are strong enough
Explain the role of the soma/cell body
Combines the electrical signals received from the dendrites to send them down the axon
Explain the role of the axon
Responsible for transmitting the neuron’s electrical signals to other cells, either neurons or muscles
Thicker axons transmit impulses faster, and axons can be myelinated to increase speed
Explain the role of the myelin sheath
Increases the speed at which electrical impulses propagate along the axon and also helps in protecting the nerve fibre
Explain the role of the nodes of ranvier
Facilitate the rapid conduction nerve impulses along the axon by forcing the electrical impulse to jump from one node to the next
Process is called saltatory conduction
Explain the role of the axon terminal
Involved in releasing neurotransmitters (chemicals that transmit signals to other neurons or effectors)
Explain the role of the synapse
Allows neurons to pass signals to other neurons, muscles, or glands
Where neurons are transferred/received by the dendrites of neighbouring cells
What are the primary types of neurons?
Motor neuron
Sensory neuron
Interneuron
What is a motor neuron?
Transmit signals from the CNS to the somewhere else (e.g., to the muscles causing them to contract)
They play a key role in movement (both voluntary and involuntary)
What is a sensory neuron?
Transmit sensory information from the PNS to the CNS
Convert external stimuli into internal electrical impulses
What is an interneuron?
Located in the CNS, communicate internally an intervene between sensory inputs and motor outputs
What is grey matter?
Comprises neuronal cell bodies, dendrites, glial cells
Involved in muscle control, memory, sensory perception, speech etc.
Predominately found in the cerebral cortex
What is white matter?
Composed of axons coated in myelin sheath
Connects different brain regions and facilitates rapid transmission of nerve signals
Larger volume of brain compared to grey matter
What is a neural impulse transmission?
Process by which neurons send and receive signals to each other
Also called the conduction of action potentials
What are the steps of an action potential? (7)
Resting potential
Depolarization
Rising phase
Repolarization
Hyperpolarization
Refractory period
Restoration
Explain resting potential
Resting potential of about -70mV that is maintained by the sodium potassium pump
Na+ (sodium) occupies the outer space
K+ (potassium) occupies the inner space
Explain depolarization
Occurs when a signal is strong enough to pass the threshold, which triggers the opening of the Na+ channels
Na+ rush into the neuron causing the internal to become more positive
Explain repolarization
Na+ channels close and K+ channels open slowly
K+ flow outside the neuron cause the membrane potential to be more negative
Explain hyperpolarization
Occurs when the membrane potential temporarily becomes more negative than the resting potential
*think: K+ door doesn’t close fast enough which allows too many to flow through
Explain refractory period
Occurs after an action potential
Period of time where no new action potential can be initiated
What are the 3 major parts of the brain?
Cerebrum
Cerebellum
Brainstem
What is the largest part of the brain?
Cerebrum
How is the cerebrum divided
Divided into left and right hemispheres, each controlling opposite sides of the body
Further divided into four lobes: frontal, parietal, occipital, and temporal
What is the cortex?
Surface of the cerebrum which has a variety of ridges (gyrus) and grooves/valleys (sulcus)
*think: valley girls suck, suck = sulcus
sulcus = shallow groove
*think both start with s
fissure = deep groove
What is the corpus collosum?
What links the two hemispheres of the brain and enables them to communicate with each other
*looks like cauliflower
Explain the role and location of the frontal lobes
Located in the front of the cerebrum
Major role in the planning of physical movement for all parts of the body
*think: CEO
Explain the role and location of the parietal lobes
Located at the top of the cerebrum, behind the frontal lobes
Role in processing incoming sensory information
*think: process + parietal both start with p
Explain the role and location of the temporal lobes
Located along the side of the cerebrum
Contains the primary auditory centre
Explain the role and location of the occipital lobes
Located at the back of the cerebrum
Processes visual information
*think: eyes on the back of my head
What is the cerebellum?
Located under the cerebrum
Receives inputs from different systems
Sends signals to the motor cortex to assist in fine-tuning skilled motor activities
What is the brainstem?
Controls vital life functions such as breathing, heart rate and blood pressure
Acts as a relay centre for messages between the brain and the spinal cord
*think: brain sends motor commands that get mediated in the brainstem
What 3 parts are included in the brainstem?
Midbrain, pons, and medulla
What is the function of the basal ganglia?
Only type of ganglia located in the CNS
Receives motor information from the primary motor cortex
Modifies movements to ensure successful execution of motor plan
Fine-tuned motor plan is sent back to the motor cortex through the thalamus to relay structure
What is the function of the thalamus?
Acts as the main relay station for sensory information heading to the cerebral cortex
Decides if it goes to the CNS or not
*think: thank you or thank you next
What is the function of the amygdala?
Involved in processing emotions like fear, anger, and pleasure
Plays a role in determining what memories are stored and where
Where is Broca’s areas located?
In the frontal lobe, typically left hemisphere
What is the function of Broca’s area?
Crucial for speech production and language processing
Damage can lead to Broca’s aphasia, which affects speech fluency
*think: BROCa = BROKEn
Where is Wernicke’s area located?
In the temporal lobe, typically left hemisphere
What is the function of Wernicke’s area”
Essential for language comprehension
Damage can lead to Wernicke’s aphasia which affects language comprehension
What is the arcuate fasciculus?
A bundle of nerve fibres connecting Broca’s and Wernicke’s areas
Essential for coordination and fluent speech (how they communicate)
What is the function of the motor cortex?
Coordinated the movements required for speech
Sends signals to speech muscles for sound production
What is the function of the auditory cortex?
Important for processing and understanding sounds
Helps monitor and adjust speech
What is the function of the angular gyrus?
Involved in transforming written language into verbal form
What is the function of the supplementary motor area and pre-motor cortex?
Involved in planning complex movements, including speech
What is EEG?
Non-invasive method to record electrical activity of the brain to understand brain function
Monitor real-time brain activity
What does EEG detect?
Fluctuations in electrical activity in the brain, primarily from the cerebral cortex
What does the EEG setup include?
Electrons (usually made of silver, silver chloride, or gold), amplifiers, a recording device, and a computer for analysis
How are EEG electrodes placed?
Using the 10-20 system which refers to the distances between adjacent electrodes
What are the four anatomical landmarks for EEG placement?
Nasion (front of the head)
*think: nasion, nose
Inion (back of the head)
*think: idiot backslap
Two preauricular points (in front of each ear)
What are some applications of EEG?
Clinical uses include diagnosis and monitoring of conditions like epilepsy and sleep disorders
In research, EEG is used for studying cognitive processes and neurofeedback
What does N100/P200 refer to?
A negative peak at 100ms after the onset of a crucial word, followed by a positive peak around 200ms
Associated with phonetic oddballs
What does N400 refer to?
A negative peak after about 400ms from the onset
Associated with semantic mismatch/anomaly
What does P600 refer to?
A positive peak after about 600ms
Associated with syntactic anomaly
What does pre-processing mean when analyzing EEG data?
Filtering out noise
What does epoching mean when analyzing EEG data?
Segmenting data around an event
*think: pouching it in
What are some challenges and considerations for EEG?
Artifacts (eye movements, muscles activity)
Individual variations
Need for controlled experimental set ups
