Midterm 1 Flashcards
(113 cards)
1
Q
The brain reaches what percent of its normal adult volume by age 6?
A
90%
2
Q
Following conception, the nervous system starts to develop after ___ weeks
A
3 weeks
3
Q
True or False: at birth you have more neurons than you will at any point in your life
A
True, you are born with all of your neurons
4
Q
When born, are your axons myelinated?
A
No, myelination happens postnatally because myelin would make a baby too heavy to birth
5
Q
What are the 7 stages of neural development, in order?
A
- Neurogenesis
- Neuronal migration
- Neuron differentiation
- Dendrite and axon growth
- Formation of synapses
- Neuron death/pruning
- Formation of myelin
6
Q
What occurs in the Neurogenesis stage?
A
It begins with segregation of the neuronal plate from the ectoderm
The neuronal plate folds to form the neuronal groove
7
Q
The process of neural stem cells differentiating into different mature neural cell types is called
A
Embryogenesis
8
Q
What cells differentiate to produce neurons?
A
Neuroblasts
9
Q
What cells differentiate to produce glia?
A
Glioblasts
10
Q
Brain cells are post-mitotic, what does that mean?
A
It means that they are matured at birth and they cannot divide anymore
11
Q
What are the only 3 regions in the adult brain that can do neurogenesis?
A
Dentate gyrus (in the hippocampus)
Striatum
Subventricular zone and olfactory bulb
12
Q
What cells from myelin in the CNS? Can they regenerate?
A
Oligodendrocytes
No, they cannot be repaired once damages
13
Q
What cells form myelin in the PNS? Can they regenerate?
A
Schwann cells
Yes, they are able to regenerate/repair themselves after being damaged
14
Q
When do astrocytes and oligodendrocytes begin to develop?
A
After most neurogenesis is complete
15
Q
What are the 3 main modes of neuronal migration
A
Radial Migration
Tangential Migration
Axophilic Migration
16
Q
Radial Migration
A
During corticogenesis, younger neurons migrate past older ones, moving along radially-oriented glial cells (called somal translocation)
17
Q
Tangential Migration
A
Mainly cortical interneurons that follow trophic chemicals produced by targets sought by axons
18
Q
Axophilic Migration
A
Neurons that migrate along the anterior-posterior axis follow the pre-existing tracts
19
Q
Dendritic Development
A
- Progressive arborization
- Growth of dendritic spines
- Slow process, continues after birth
20
Q
Morphogen
A
The chemicals that direct the differentiation and growth of neurons into a specific shape
21
Q
Exuberant Synaptogensis
A
The dramatic proliferation of synapses during early brain development
> But synapses happen all throughout the lifetime
22
Q
Synaptic Pruning
A
A reduction of the number of synapses of adults following the “use it or lose it” rule
23
Q
5 Phases of Synaptic Formation and Pruning
A
1 & 2: Generated independently of experience
- Rapid growth
- Plateau and rapid elimination throughout puberty
- Plateau in middle age and stead decline with age
24
Q
Experience-expectant neuronal changes
A
Genetically driven development of neuronal infrastructure
25
Experience-dependent neuronal changes
Results from the personal experiences of an individual
26
True or false, the brain has growth spurts
True
27
Environmental characteristics affect brain development at ___age(s)
All
| > Mostly prenatal and early postnatal
28
Neuroplasticity
The ability of nervous tissue to change the mapping of neural function to neural structure
29
Can all brain regions be changed by experience?
No, some are genetically predetermined and stay the same no matter what you do, like the hypothalamus.
30
Why do we have neuroplasticity?
It is evolutionarily adaptive to be able to adapt to our environment. The brain must be able to calibrate itself to the other body systems because it cannot "know" about the characteristics of body parts as they were independently inherited.
31
What are "critical periods" in neuroplasticity?
Limited time frames when brain regions show maximum plasticity.
32
2 general types of plasticity
Ones that have a critical period
| Ones that are plastic forever
33
7 pieces of evidence for neuroplasticity
1. Change in behaviour
2. Change in brain anatomy
3. Change in functional brain maps
4. Changes in synaptic organization
5. Changes in physiological organization
6. Changes in molecular structure
7. Cellular mitosis
34
Transduction/Detection
Converting stimulus events into neural events
35
Larger brain size allows for: (4)
- More memory capacity
- Abstract thinking
- Symbols are possible and used to communicate information
- Improved ability to communicate with each other
36
Most neurons are which type of neuron?
Interneurons
37
Neurons use __x as much ATP as other cells
3 times
38
Transmembrane Potential
The voltage difference across the cell membrane
39
The typical resting potential of a cell
~-70mV
40
Depolarization (less polarized)
Reduction (towards 0 V) of the membrane potential of a cell from its normal resting potential
41
Hyper-polarization (more polarized)
An increase in membrane potential of a cell relative to the resting potential
42
Action potentials propagated along the length of axons act as a communication signal from the ___ ___ to the ___ ___ at the end of the axon.
Axon Hillock
| Synaptic buttons
43
Signals transmitted within a neuron are mainly ___
Electrical
44
Signals transmitted between neurons are mainly ___
Chemical
45
After a cell fires it goes into a refractory period, what does that mean?
After a cell fires it needs to regenerate its resting potential, in this time the cell is unable to fire
46
Over shoot (cell firing)
After cell firing, during the refractory period, the cell hyper-polarizes past the resting potential ~-90mV
47
6 stages of ions in cell firing
1. When the excitation threshold is met, Na+ channels open and Na+ enters the cell
2. K+ channels open, K+ enters the cell
3. (Action potential peak) Na+ channels become refractory, no more Na+ enters the cell
4. K+ continues to leave the cell, causes membrane potential to return to resting level.
5. K+ channels close, Na+ channels reset
6. (Hyperpolarized) Extra K+ outside diffuses away
48
Which axon of what animal is used in research?
The giant axon of the squid (not a giant squid)
49
What voltage is the excitation threshold?
About +10mV from resting potential (so ~-60mV)
50
What voltage is reached at the peak of an action potential
+30mV
51
When is the neuron in absolute refractory (cannot fire) and in relatively refractory (can only fire with a really big EPSP)?
The cell is in absolute refractory in the rise and fall of the action potential
Relatively refractory at the end of an action potential when the cell is hyperpolarized
52
Do all action potentials carry information?
No, there are some action potentials that are "noise" which are spontaneous actions potential that don't mean anything
53
What is the use of IPSPs?
- Inhibition allows for the conservation of energy
| - It allows for more "combinations" of firing
54
Where are neurotransmitters produced and stored?
Within the neuron
55
Information is transmitted between two neurons when:
1. The pre-synaptic membrane releases NT into the synaptic cleft
AND
2. The NT bind to certain receptors on the post--synaptic membrane
56
Excitatory Post Synaptic Potential (EPSP)
An excitatory depolarization on the membrane of the dendrite that make an action potential more likely
57
Inhibitory Post Synaptic Potential
An inhibitory hyperpolarization on the membrane of the dendrites that make an action potential less likely
58
What is neural integration and what are the two types?
It is the sum of the IPSPs and EPSPs in a short period of time that will determine whether there is an action potential.
Temporal - they need to happen in close after each other
Spatial - they need to happen in close proximity to each other
59
Rate Law
The intensity of a stimulus is carries in the rate of action potentials (not the intensity)
60
Neural Coding
Special patterns of firing that allow for more info to be carried than would be able with 100 action potentials/sec
61
Release Zone
A region of the interior of a presynaptic membrane of a synapse to which synaptic vesicles attach and release their neurotransmitters into the synaptic cleft
62
Nervous System Agent
Any chemical capable of changing any aspects of the processes of neural communication
> typically dose dependent
63
Dose Response
```
The function relating the dose level of a drug to the drug's effect on the nervous system and/or other body tissues
Where 50% of people have this effect:
Therapeutic or "Effective" dose
Toxic dose
Lethal dose
```
64
Side Effects
Unintended consequences on the nervous system of a drug (either harmful or not)
65
Contraindictions
Negative side effects
66
Nervous System Agonist
Drugs that increase the rate of synaptic communication via NT
67
Nervous System Antagonists
Drugs that decrease the rate of synaptic communication via NT
68
2 types of Agonists
1. Direct Binding = drugs that directly bind to the post synaptic receptors
2. Indirect Binding = agonists that enhance the neurotransmitter action by stimulating NT release
69
2 types of Antagonists
1. Direct Acting = block NT from binding to the receptors
| 2. Indirect Acting = inhibit release or production of NT
70
Learn the 11 ways that drugs affect neural communication mechanisms and an example of a drug for each
Picture in photos
71
Drug substitutes for one of the precursor chemicals involved in production of NT
Agonist
| >L-DOPA
72
Drug inhibits production of NT by a precursor chemical (messes up one of the building blocks)
Antagonist
| >PCPA
73
Drug prevents storage of NT in vesicles (so NT leak out of terminal and cannot be released when needed)
Antagonist
| >Reserpine
74
Drug stimulates release of NT in vesicles
Agonist
| >Latrotoxin
75
Drug inhibits release of NT
Antagonist
| >Botulinum toxin (botox)
76
Drug stimulates postsynaptic preceptors
Agonist
| >Nicotine
77
Drug blocks postsynaptic receptors
Antagonist
| >Atropine
78
Drug stimulates autoreceptor action
Antagonist
| >Apomorphine
79
Drug blocks autoreceptor action
Agonist
| >Clonidine
80
Drug blocks reuptake of NT in synapse
Agonist
| >Cocaine
81
Drug inactivates acetylcholinesterase
Agonist
| >Physostigmine
82
6 ways of taking nervous system agents
- Oral route (most convenient, safest)
- Direct injection into brain (most direct and fastest)
- Intramuscular injection (slowest)
- Inhalation (fewer "barriers" on way to brain)
- Transdermal (patch)
- Intravenous injection (fastest practical way)
83
What is the blood brain barrier?
The feet of astrocytes wrap around the endothelial cells of the capillaries to block any holes between them. They allow only small, non-ionized molecules to pass through the wall. It protects the brain with its selective permeability
84
3 regions of the brain without a blood brain barrier
1. Pituitary Gland - must be able to receive and send out hormones
2. Area Postrema - region that triggers vomiting in response to blood-borne toxins
3. Pineal Gland - affected by cycling hormones
85
5 Classes of Psychoactive Drugs
1. Anxiolytics (Benzodiazepine)
2. Euphoriants (MDMA)
3. Stimulants (caffeine)
4. Depressants (Barbiturates)
5. Hallucinogens (LSD)
86
6 Steps of Hormone Signalling
1. Making hormone
2. Storage and secretion
3. Transport to target cell
4. Recognition of hormone by target cell
5. Signal transduction cascade
6. Breakdown hormone
87
What are the differences between neurotransmitters and hormones
- Hormones can signal over longer distances and longer time scales
- Hormones travel all over whereas NT are targeted
- Neural signals are much faster (milliseconds) hormones are much slower (seconds, minutes, hours)
- Neurotransmitters is "all or nothing" whereas hormone signalling is continuously variable and dependent on concentration
88
2 types of hormones
Steroid - fat soluble and synthesizes from cholesterol, can enter target cells directly
Peptide - Bind to metabolic receptors on the cell generating a 2nd messenger
89
Hormone Functions (3)
Homeostasis
Reproduction
Stress (Glucocorticoids)
90
SAME DAVE
```
Sensory = Afferent
Motor = Efferent
```
```
Distal = Afferent
Ventral = Efferent
```
91
Sensory receptors are _____
Specific
| > They only respond to certain types of mechanical, chemical or electromagnetic energy
92
True or false, all sensory signals end up in the cerebral cortex
False
93
Transduction
Energy that ultimately results in neural signalling
94
Receptive Field
A specific part of the world (or body) to which a sensory receptor responds (a spatial location)
95
Cortical Magnification Factor
The amount of cortex that is dedicated to a body part related to the sensitivity of the body part, NOT its actual size
96
Adaptation
The change over time of the responsiveness of the sensory system to a constant stimulus
97
Sustained Response
Neural response to stimulus remains constant as long as a stimulus is present
98
Transient Response
Only responds to a change in the stimulus (when a stimulus begins, ends, or otherwise changes)
99
Exteroceptive receptors
Receptors that respond to external stimuli (like skin or eyes)
100
Interoceptive Receptors
Receptors that respond to bodily stimuli (like in gut)
| Help interpret meaning of external stimuli
101
Is it the number or density of receptors that determines sensitivity?
Density determines sensitivity
102
Neural Relays
- Receptors connect to the cortex through a sequence of intervening neurons
- Allows sensory systems to interact and produce relevant reactions
103
On Centre Cell
The eye cell will produce an action potential when there is stimulation in the middle of its visual field
104
Off Centre Cell
The eye cell will become hyperpolarized when there is stimulation in the middle of the visual field
105
How are visual stimuli coded in higher level cortex?
The neuron in the cortex will fire most for an stimulus at a certain configuration, and then will fire less for unfavoured configurations
106
Many neurons are Polymodal, what does that mean?
Their receptive fields are sensitive to more than one type of sensory stimulus (live both sound an light)
107
Each sensory system projects to where?
The cerebral cortex to its primary cortex
108
What do secondary areas do?
They get information from the primary cortex and perform specific aspects of the sensory modality
109
What are the 4 major somatosensory submodalities?
1. Nocioception
2. Hapsis
3. Proprioception
4. Balance
110
Nocioception
Perception of unplesant stimuli
| > pain and temperature
111
Hapsis
Perception of objects using fine touch and pressure (object recognition through touch)
112
Proprioception
Sense of your body in space
113
What are the 2 major somatosensory pathways?
```
Dorsal Tract (Hapsis and Proprioception)
Ventral Tract (Nocioception)
```
