Neuroscience (L1-4) Flashcards
(72 cards)
1
Q
Multiple sclerosis
A
- Neurological condition caused by demyelination of axons, causing slower transmission
- Symptoms include fatigue, vision problems and difficulty walking
2
Q
Propogation of an AP
A
- Initiated at the axon hillock
- Move down an axon using saltatory conduction (jumps between unmyelinated nodes of Ranvier)
- Myelin prevents any charge leakage through the axon
3
Q
Blood-brain barrier
A
- Semi-permeable barrier between blood and brain
- Produced by tightly packed cells in the capillary walls of the brain
- Protects and helps to regulate the chemical balance of the brain
- Small uncharged, lipophilic molecules can cross
- Other substances access the brain via active transport
4
Q
What is the…
- Central nervous system
- Peripheral nervous system
A
CNS - brain and spinal cord
PNS - connects CNS to the organs and muscle
5
Q
What is the neuron doctrine?
A
- The idea that the brain consists of individual neurons
- Shown by Santiago Ramon y Cajal using staining techniques
6
Q
Glial cells
A
- Astrocytes provide structure, supply neurons with nutrients and oxygen and modulate neurotransmission
- Microglia remove dead neuronal tissue and provide immune defence
- Oligodendrocytes (CNS) and Schwann cells (PNS) insulate nerve cells with myelin sheaths
7
Q
Rett Syndrome
A
- Affects young females
- Caused by mutations in the MECP2 protein
- Symptoms include loss of speech and motor control, seizures, orthopedic and digestive problems, anxiety, etc.
8
Q
Neurons
A
- Perform information processing tasks
- Specialised depending on their location
- Soma contains nucleus, mitochondria, ribosomes and ER
- Dendrites are branching fibres that receive info from other neurons via synaptic receptors
- Axons are thin fibres that transmit info to other neurons
9
Q
Membrane potential
A
- Resting membrane potential = -70mV
- Penetrable for small uncharged molecules
10
Q
Action potentials
A
- If stimulation exceeds the threshold of -55mV, an AP is triggered (all-or-none)
1. Na+ channels open = Na+ flows in = inside more positive = depolarisation to +40mV
2. K+ channels open = K+ flows out = repolarisation
3. Refractory period occurs where an action potential cannot be initiated
4. Na+/K+ pump restores resting potential by moving 3 Na+ out and 2 K+ in
11
Q
Synapses
A
- Junctions at which signal is passed from one neuron to another
- Delay transmission (Charles Sherrington showed reflexes are slower than conduction along axon)
- Synaptic transmission is chemical (shown by Otto Loewi)
12
Q
Neurotransmitters
A
- Synthesised by presynaptic neuron
- Stored in vesicles in axon terminal
- Released in synaptic cleft via Ca2+-dependent mechanism
- Bind to receptors on postsynpatic neuron
13
Q
How do neurons work?
A
- Act as an information integrator and a decision maker
- Combine excitatory and inhibitory inputs to determine whether to fire
14
Q
Receptors
A
- Protein embedded in the membrane that matches molecular shape of a neurotransmitter
- Ionotropic receptors are ligand-gated (fast and short-lived effect)
- Metabotropic receptors are GPCRs (slow and longer-lasting effect)
15
Q
Excitatory postsynaptic potential (EPSP)
A
Depolarisation of the neuron that increases the rate of APs in the postsynaptic neuron
16
Q
Inhibitory postsynaptic potential (IPSP)
A
Hyperpolarisation of the neuron that decreases the rate of APs in the postsynaptic neuron
17
Q
Temporal summation
A
When rapid repeated sub-threshold stimulations of a presynaptic neuron accumulate
18
Q
Spatial summation
A
When postsynaptic inputs arriving simultaneously at different locations on the dendrites are combined
19
Q
What are the neurotransmitter differences between species?
A
- Variations in the number of synapses
- Amount of neurotransmitter release
- Sensitivity of receptors on postsynaptic cells
20
Q
Acetylcholine (ACh)
A
- Involed in motor control
- Regulates attention, learning, memory and sleeping
- Involved in Alzheimer’s disease
21
Q
Dopamine
A
- Influences movement, motivation, emotional pleasure and arousal
- High levels linked with schizophrenia
- Low levels linked with Parkinson’s disease
22
Q
Glutamate
A
- Excitatory NT involved in learning and memory
- High levels linked with migraines and seizures
23
Q
GABA
A
- Inhibitory NT
- Low levels linked to seizures, tremors and insomnia
24
Q
Noradrenaline
A
- Controls mood and arousal
- Low levels linked to depression
25
Serotonin
- Regulates hunger, sleep, arousal and aggression
| - Low levels linked to depression
26
Endorphins
- Act within pain pathways and emotion centres of the brain
| - Low levels can lower pain threshold
27
How is the action of neurotransmitters terminated?
- Re-uptaken
- Degraded
- Reabsorption
28
Psychoactive drugs
- Drugs facilitate or inhibit transmission at synapses
- Agonists mimic and increase the effects of a NT
- Antagonists block the effects of a NT
29
Myasthenia Gravis
- Autoimmune disease caused by inhibition of ACh receptors
- Symptoms include fluctuating muscle weakness and fatiguability
- Treated with AChE inhibitors
30
Name two narcotics
Morphine and opiates
31
Name a hallucinogen
LSD
32
Abused drugs
- Most stimulate the release of dopamine from the nucleus accumbens
33
Cocaine
- Local anaesthetic (blocks Na+ channels to interfere with the propogation of APs)
- Stimulant (activates CNS to produce arousal and elevated mood)
- Potentiates the effect of dopamine and serotonin by blocking their reuptake
34
Autonomic nervous sytem
- Part of the peripheral nervous system
- Sympathetic division uses noradrenaline for 'fight or flight'
- Parasympathetic division uses acetylcholine for 'rest and digest'
35
What are the 3 planes of the brain?
- Coronal: view from the front
- Horizontal: view from above
- Sagittal: view from the side
36
Coordinate system of the brain
- Anterior (closer to front) or posterior (closer to back)
| - Superior/dorsal (closer to top) or inferior/ventral (closer to bottom)
37
What are the 3 major parts of the brain formed during development?
- Hindbrain
- Midbrain
- Forebrain
- Hindbrain and midbrain form the brainstem
38
Hindbrain
- Medulla: coordinates heart rate, circulation and respiration (contains the reticular formation which regulates sleep and arousal)
- Pons: a major relay at which axonal projections become contralateral (cross sides)
- Cerebellum: controls fine motor skills, coordination, balance and cognitive functions
39
Midbrain
- Contains structures that have secondary roles in vision, audition and movement
- Superior colliculi: help guide eye movements and fixation of gaze
- Inferior colliculi: help sound localisation
- Substantia nigra: plays a role in reward, addiction and projects to the basal ganglia to integrate movements
- Tectum: orients an organism
- Tegmentum: involed in movement and arousal
40
Forebrain's diencephalon
- Thalamus: relays and filters information from sensory organs and transmits it to the cortex
- Hypothalamus: regulates body temperature, hunger, thirst and sexual behaviour
- Mamillary bodies: relay for impulses coming from the amygdala & hippocampus
41
Forebrain's limbic system
- Hippocampus: creating, storing and combining memories
- Amygdala: emotional behaviour and formation of emotional memories
- Cingulate cortex: linking behavioural outcomes to motivation and learning
42
Cerebral cortex
- Part of the forebrain
- Consists of grey matter
- Wrinkled/convoluted to increase SA
- Gyri are ridges
- Sulci are groves (called fissures if deep)
- Split into Broadmann's map of 52 areas
43
Cerebral hemispheres
- Left and right hemispheres communicate via the corpus callosum (dense band of fibres at bottom of longitudinal fissure)
- Corpus callostomy is a surgical procedure that disconnects the cerebral hemispheres resulting in a condition called ‘split-brain’
- Each hemisphere has 4 lobes
44
Frontal lobe
- Anterior to the central sulcus and superior to the lateral fissure
- Important for movement and complex human capabilities
- Broca’s area - important for speech production
- Primary motor cortex
- Prefrontal cortex - plays a role in organizing, planning, decision making and impulse control (damage impairs impulse control)
- A frontal lobotomy is a surgical procedure that disconnects the prefrontal area from the rest of the brain
45
Parietal lobe
- Posterior to the central sulcus
- Important for body sensations and spatial localisation
- Primary somatosensory cortex
- Parietal association areas: combine info from body senses and vision
to dentify objects by touch, determine the location of limbs and locate objects in space
46
Occipital lobe
- At the posterior of the brain
| - Processes visual information in the primary visual cortex
47
Temporal lobe
- Located laterally on the brain (sides)
- Primary auditory cortex
- Language, auditory and visual association areas (eg. Wernicke's area for language comprehension and production)
48
What is phrenology?
- The correlation of brain anatomy with behaviour/personality
- Proposed by Franz Joseph Gall
49
How can brain lesions be stimulated?
- Invasive: use stimulating electrodes
- Non-invasive: trancranial magnetic stimulation (TMS) where neurons are excited/inhibited by externally applied electromagnetic field
50
How can the electromagnetic activity of a single neuron be recorded?
- Use of microelectrodes which impale the cells of interest
| - A nano lead is implanted into an axon and records neural activity without stimulating it
51
What are grandmother cells?
- Responds to only one stimulus (eg. name/ image of a celebrity)
- Discovered by Quigora et al.
- Shows that visual info is stored in a localised way
52
How can the electromagnetic activity of a neuron population be recorded?
Electroencephalography (EEG)
- Measures brain activity on the scalp
- Sensitive to postsynaptic dendritic currents generated by a population of neurons that are active in synchrony
- Uses a cap with implanted electrodes placed in a specific arrangement
- Used for diagnosing epilepsy (displays spike and wave)
53
Event-related potentials (ERPs)
- EEG activity time-locked to an external event (eg. sound, visual signal)
- Good temporal resolution
- Poor spatial resolution
54
Magnetoencephalography (MEG)
- Recording of magnetic fields produced by electrical currents in the brain using arrays of SQUIDs
55
Neuron staining techniques
- Golgi staining - stains about 5% of neurons
- Myelin stains - stains axon
- Nissl stains - stains somas
56
CT scans
- Computerised tomography
- A contrast dye is injected into the blood
- Combines multiple x-ray photos from different angles
- Based on the fact that x-ray absorption varies with tissue density (higher density = lighter)
57
MRI
- Magnetic resonance imaging
- A strong magnetic field is applied and then ceased
- The energy released by molecules in the tissue as a result of the pulse is measured
- Differently charged molecules respond differently to the pulses, hence the energy signals reveal brain structures with different molecular composition
58
PET scan
- Positron emission tomography
| - Measures local blood flow in a brain region using a radioactive tracer
59
fMRI
- Functional MRI
- Measures brain activity by detecting the levels of deoxyhemoglobin (BOLD response)
- Active neurons consume oxygen and convert oxyhemoglobin into deoxyhemoglobin
60
Syndactyly
A condition in which fingers are connected by skin tissue
61
Phantom pain
- When amputees experience pain in their missing limb
| - Caused by neurons from other body areas invading area that normally receives input from the missing limb
62
What are the 3 main types of neurons?
- Sensory neurons receive information from the external world and convey it to the brain via the spinal cord
- Motor neurons carry signals from the spinal cord to the muscles to produce movement
- Interneurons connect sensory neurons, motor neurons and other interneurons
63
Spinal reflexes
Simple pathways that rapidly generate muscle contractions without input from the brain
64
Forebrain's basal ganglia
- Basal ganglia: involved in planning behaviour and emotional expresion
- Pituitary gland: releases hormones
65
Central nervous system
- In vertebrates separates sensory (back) and motor (front) processing
- Higher levels perform more complex functions
66
What is meant by 'degree of relatedness'?
The probability of sharing genes
67
Epigenetics
- The mechanisms of interaction between genes (nature) and the environment (nurture)
- Genes express themselves within an environment
- Genetic methylation silences a gene
68
Heritability
- A measure of the variability of behavioural traits among individuals that can be accounted for by genetic factors
- 0 = genes don't contribute to individual differences
69
Phineas Gage
- Had an iron rod propelled through his frontal lobe
- Became irritable, irresponsive and indecisive
- Evidence that the frontal lobe is involved in emotion regulation, planning and decision making
70
Executive functions
- Hot EFs include impulses that take over our thoughts
| - Cold EFs are logical choices that require rationality
71
What is prosopagnosia?
The inability to recognise faces
72
Hubel + Wiesel
- Inserted electrodes into the occipital lobes of anaesthetised cats and observed the AP signals
- Primary visual cortex are activated when a contrast between light and dark occurs in part of the visual field
- Each neuron responds to a particular orientation and are called feature detectors
