trivia Flashcards

1
Q

sensory neurons

A

none

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2
Q

motor neurons

A

none

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3
Q

interneurons

A

These are by far the most numerous (in the

human brain)

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4
Q

glial cells

A

long thought to have a purely

supporting function to the neurons

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5
Q

cerebral cortex

A

cortical tissue is the most highly
developed area of the brain in humans - four times bigger
than in gorillas

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6
Q

lateralization of the brain

A

Many of the cortex’s functions are carried out by
both sides of the brain, but some are largely lateralised to
one cerebral hemisphere or the other. Areas concerned with
some of these higher functions, such as speech (which is
lateralised in the left hemisphere in most people), have been
identified.

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7
Q

On the receiving side of the cell, the dendrites have close
contacts with incoming axons of other cells, each of which is
separated by a miniscule gap of __. These junctional spots are
named __, from __ words that mean “__”.

A

On the receiving side of the cell, the dendrites have close
contacts with incoming axons of other cells, each of which is
separated by a miniscule gap of about 20 billionths of metre. These junctional spots are
named synapses, from classical Greek words that mean “to
clasp together”.

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8
Q

Cajal

A

Ramon Y Cajal, father of modern neuroscience. photograph shows him in 1890.

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9
Q

Hodjkin

A
Alan Hodgkin and Andrew
Huxley won the Nobel Prize
for discovering the
mechanism of transmission
of the nerve impulse.
They used the "giant axon"
of the squid in studies
at the Plymouth Marine
Biology Laboratory
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10
Q

Huxley

A
Alan Hodgkin and Andrew
Huxley won the Nobel Prize
for discovering the
mechanism of transmission
of the nerve impulse.
They used the "giant axon"
of the squid in studies
at the Plymouth Marine
Biology Laboratory
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11
Q

action potential speed

A

in myelinated neurons,

action-potentials can race along at 100 metres per second!

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12
Q

action potential frequency

A

The most efficient axons can
conduct action potentials at frequencies up to 1000 times
per second.

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13
Q

synaptic cleft

A

20 nanometer gap that the chemical messenger diffuses across

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14
Q

excitatory and inhibitory neurotransmitters

A

The main excitatory neurotransmitter in the brain is
glutamate. There are
two inhibitory neurotransmitters – GABA and glycine.

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15
Q

synaptic transmission time

A

Synaptic transmission is a very rapid process: the time
taken from the arrival of an action potential at a synapse to
the generation of an epsp in the next neuron is very rapid -
1/1000 of a second.

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16
Q

alcohol dependency

A

about one in ten of regular drinkers will become dependent

alcoholics

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17
Q

alcohol deaths

A

More than 30,000

people die every year in Britain from alcohol-related diseases.

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18
Q

pregnancy and alcohol

A

Pregnant mothers who drink run the risk of having

babies with damaged brains and low IQ’s.

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19
Q

smoking deaths

A

More than
100,000 people die every year in Britain from smoking-related
diseases.

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20
Q

cannabis dependency

A

About one in ten users may become

dependent

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21
Q

cannabis and mental illness

A

Although not yet proven,
there is some evidence that heavy use by young people might
trigger the mental illness schizophrenia in
susceptible individuals.

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22
Q

“mid-week blues”

A

Animal experiments have shown that Ecstasy can
cause a prolonged, perhaps permanent reduction of
serotonin cells. This might account for the “mid-week blues”
suffered by weekend ecstasy users. Every year, dozens of
young people die after taking it

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23
Q

amphetamines and mental illness

A

Frightening schizophrenialike

psychosis can happen after Dexedrine and Speed.

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24
Q

amphetamines

A

man-made chemicals that include
“Dexedrine”, “Speed”, and the methamphetamine derivative
called “Ecstasy”. also d-LSD

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25
heroin
a man-made chemical derivative of the plant product morphine. a very dangerous drug that can kill in even modest overdose (it suppresses breathing reflexes).
26
cocaine
plant-derived chemical which can cause intensely pleasurable sensations as well as acting as a powerful psychostimulant.
27
receptive field size
Pacinian corpuscles have | much larger receptive fields than Meissner’s corpuscles
28
animal experiments on the pain threshold
Animal experiments have revealed that electrical stimulation of brain areas such as the aqueductal gray matter causes a marked elevation in the pain threshold and that this is mediated by a descending pathway from the midbrain to the spinal cord.
29
example of endogenous opioid
met-enkaphalin
30
hyperalgesia
enhanced pain. There is a lowering of the pain threshold, an increase in the intensity of pain, and sometimes both a broadening of the area over which pain is felt or even pain in the absence of noxious stimulation. This can be a major clinical problem. Hyperalgesia involves sensitisation of the peripheral receptors as well as complex phenomena at various levels of the ascending pain pathways.
31
science behind acupuncture
Forty years ago, a research laboratory was set up in China to find out how it works. Its findings reveal that electrical stimulation at one frequency of vibration triggers the release of endogenous opoiods called endorphins, such as met-enkephalin, while stimulation at another frequency activates a system sensitive to dynorphins.
32
how do photoreceptors work?
respond to the light that hits them by generating tiny electrical potentials. These signals pass, via synapes through a network of cells in the retina, in turn activating retinal ganglion cells whose axons collect together to form the optic nerve. These enter the brain where they transmit action potentials to different visual regions with distinct functions.
33
photoreceptor light sensitivty comparison
rods are about 1000 times more sensitive to light than the other, less numerous category called cones.
34
genetic basis of colorblindness
due to the absence | of certain visual pigments
35
types of retinal ganglion cells
About 90% of these cells are very small, while another 5% are large M-type or magnocellular cells. We shall see later that abnormalities in the M-Type cells may underlie certain cases of dyslexia
36
where are internal “representations” of visual space around us are created?
cerebral cortex
37
number of cortical layers
six
38
decision making brain region
cerebral cortex
39
behavior of V5 neurons
(V5 = MT) It turns out that activity of cells in V5 accurately reflects the strength of the movement signal. Neurons here respond selectivity to particular directions of movement, increasing their activity systematically and accurately when the proportion of dots moving in their preferred motion direction increases.
40
17th C neuro metaphor
In the 17th C, Descartes used a hydraulic metaphor to explain how the “humours” of the brain moved the muscles - a metaphor borrowed from the water engineering he saw in the gardens of French chateaux.
41
20th C neuro metaphor
At the turn of the 20th C, reflecting the industrial age, neurophysiologists described the intricate wiring of the brain as “an enchanted loom” or later as a giant “telephone exchange”.
42
21st C neuro metaphor
Now, at the start of the 21st C, computational metaphors abound, such as the fanciful speculation that “the cerebral cortex operates not unlike a private world wide web”.
43
Parkinson's and animal research
the use of L-DOPA to treat Parkinson’s disease emerged from Nobel Prize winning work on the rat brain.
44
2 replacement techniques (3 Rs)
tissue culture, computational modelling
45
seizure and brain waves
During a generalised seizure, the normal alpha rhythym of the electroencephalogram (EEG) is replaced by large, slow, synchronous waves of electrical activity in both cerebral hemispheres.
46
normal headache cause
Usually this is caused by muscle tension and is nothing serious to worry about.
47
serious headache cause
``` In these conditions the pain comes not from the brain itself, but from irritation or stretching of the meninges - the lining of the brain. ```
48
migraine cause
sensations coming from cerebral blood vessels. Brain imaging reveals increased activity in these regions at the start of a migraine. In response, there is a brief increase in local blood supply (which brings on symptoms like flashing lights), immediately followed by reduced blood flow (reflected in temporary weakness).
49
migraine meds
A new class of drugs was discovered which activated a particular subgroup of serotonin (5-HT) receptors. These drugs – triptans - are very effective at stopping a migraine headache in its tracks.
50
sign of stroke
sudden weakness down one side of the body (interruption of fuel to opposite side of the brain)
51
stroke cause
``` What has gone wrong has to do with prolonged interruption of the energy supply (blood supply) that the brain needs to function. ```
52
molecular basis of stroke
In the absence of ATP, cells cannot maintain homeostasis and they may swell up and burst. Neurons may also spontaneously depolarise, releasing potentially toxic neurotransmitters such as glutamate. And glial cells, that normally mop up excess glutamate through an ATP-dependent pump, also stop working.
53
new stroke meds
block neurotransmitters including glutamate that accumulate to toxic levels during a stroke. These drugs can either block glutamate receptors themselves or the intracellular signalling pathways that are turned on by glutamate. Many such drugs are in development. Sadly, none has yet had an impact on stroke.
54
Huntington's disease naming
named after the doctor who first | described the condition.
55
du Pre
Jacqueline du Pré – a well known musician who suffered from multiple sclerosis
56
Guillain Barre syndrome
condition that occurs when the immune system attacks the nerves as they emerge from the spinal cord.
57
dementia age
affects approximately 5% of 65 years olds and 25% of those | aged 85 or older.
58
depression meds
Antidepressant drugs, which enhance the effects of neuromodulatory transmitters such as serotonin and noradrenaline can rapidly (within weeks) treat the illness.
59
depression rate
``` The condition is surprisingly common – 1 in 5 may suffer at some time in their lives from some degree of depressive disorder. ```
60
schizophrenia rate
affects 1 in 100
61
Broca
idneitifed the speech areas of the brain. correlated oddities of mind/behavior w/ measurements of brain structure at postmortem.
62
PET disadv
There are several disadvantages of PET, the major one being that it requires the injection of radioactive tracers. This means that many people cannot have a PET scan, such as children and women of child-bearing age, and the number of measures taken during a scan are limited.
63
MRI length
30min - 1hr
64
Beatles
The profits made by E.M.I. from the sale of records by ‘The Beatles’ helped to pay for the development of the first brain scanners.
65
energy consumption in the brain
About 50-80% of the total energy consumption of the brain is consumed in the conduction of action potentials along nerve fibres and in synaptic transmission. The rest is taken in manufacturing and maintenance.
66
Gardner
an American teenager called Randy Gardner resolved to try and win his place in the Guinness book of Records by going without sleep for the longest period ever recorded. His ambition was to last 264 hours without sleep - and he did it! It was a carefully controlled experiment supervised by doctors in the American Navy.
67
sleep rhythm research animal
A big leap forward has come from neurogenetics. Various genes have been identified that, like the cog-wheels and escapement of a clock, are the molecular components of rhythmical pacemakers. Much of this work has been done in Drosophila (fruit flies) where it has been found that two genes - per and tim - produce proteins that interact together to regulate their own synthesis.
68
sleep rhythms and neurotransmitters
research has revealed a brain-stem activating system involving various neuromodulatory transmitters, including one called adenosine, in a kind of molecular chain reaction that takes us through the various sleep stages. Synchronisation mechanisms enable networks to pass from one sleep state to another.
69
activation of immune system
triggers cells called leucocytes and macrophages, and acute phase proteins that travel to the site of attack, to identify, kill and then remove invading pathogens. In addition, the acute phase response generates the symptoms we have all felt (fever, aches and pains, sleepiness, loss of appetite, disinterest)
70
where are acute phase proteins produced
liver
71
when were cytokines discovered, what are they, how many are there
20 yrs ago, they are a group of proteins, 100+
72
examples of cytokines
They include interferons, interleukins, tumour | necrosis factors and chemokines.
73
cytokine amounts
These proteins are normally produced in the body at very low levels, but are switched on quickly in response to disease or injury. Many are produced locally within damaged tissues and act on cells nearby, but some enter the blood stream where they send signals to distant organs including the brain.
74
cytokine effects
It is cytokines that cause most of the responses to disease and infection. stimulate the immune system and the key components of inflammation such as swelling, local changes in blood flow, and the release of a second wave of inflammatory molecules. They act on almost all physiological systems, including the liver where they stimulate the acute phase proteins.
75
cytokine production regulation
triggers: include bacterial or viral products, damage to cells or threats to cell survival such as toxins or low levels of oxygen. Another important regulator of cytokine production is the brain that, through neural signals to tissues (mainly via the sympathetic nervous system) or hormones (such as cortisol from the adrenal gland), can switch cytokines on or off.
76
fight or flight response physical effects
initial tingling sensation, sweating, heightened awareness, rapid pulse rate, higher blood pressure and general feelings of fear
77
fight or flight response physical effects: why do they occur
These changes happen because of receptors that are found on blood vessels, causing them to constrict and so our blood pressure to shoot up, and in the heart, causing it to accelerate and produce the pounding sensation in the chest known as palpitations. There are also receptors in the skin causing hairs to erect (goosebumps) and in the gut causing those disconcerting abdominal sensations that we all sense as stress. These changes are there to prepare us to fight or to flee - and to concentrate blood flow to vital organs, the muscles and the brain.
78
fight/flight and neurotransmitters
sympathetic nervous system is activated. After receiving a stressful challenge and computing the right response, the brain rapidly activates nerves originating from control centres in the brainstem. These cause the release of noradrenaline in a variety of structures and of adrenaline from the adrenal glands (situated just above the kidney).
79
2 major neuroendocrine responses to stress
- activation of HPA axis | - activation of sympathetic nervous system
80
brain region and HPA axis (stress)
The hypothalamus is the key brain area regulating many of our hormones. It has strong inputs from areas of the brain processing emotional information, including the amygdala, and from regions of the brainstem controlling sympathetic nervous responses. It integrates these to produce a co-ordinated hormonal output (corticotrophin releasing factor, CRF) that stimulates the next part of the circuit - the pituitary gland. In turn, this releases a hormone called adrenocorticotrophin (ACTH) into the blood. ACTH then stimulates a part of the adrenal gland to secrete cortisol.
81
cortisol feedback to the brain
The last step of the circuit is cortisol feedback to the brain. The highest density of cortisol receptors is in the hippocampus, a key structure for learning and memory, but cortisol also acts on the amygdala, which processes fear and anxiety. The net effect is to turn on the amygdala - to allow learning of fear-related information; and to turn off the hippocampus - to ensure that resources are not wasted on more complex but unnecessary aspects of learning.
82
cortisol feedback
steroid. raises blood sugar and other metabolic fuels such as fatty acids. This often occurs at the expense of proteins that are broken down into fuels required immediately - instant ‘chocolate bars’ for the muscles and brain. Cortisol also helps adrenaline to raise blood pressure and, in the short term, makes you feel good. Cortisol also turns off growth, digestion, inflammation, sex, even woundhealing.
83
brain region and cortisol
the hippocampus has high levels of the 2 receptors for cortisol, low MR and high GR. The low MR receptor is activated by the normally circulating levels of cortisol in the bloodstream highway of the HPA axis. This keeps our general metabolism and brain processing ticking over nicely. However, as cortisol levels begin to rise, particularly in the morning, the high GR receptor becomes progressively more occupied. When we become stressed, cortisol levels become very high indeed, activation of this receptor is sustained and the hippocampus is then shut down by a genetically controlled program. --> bell-shaped stress curve
84
cytokine: negative
Recent research has shown that many of the defence molecules such as cytokines are also active contributors to brain diseases such as multiple sclerosis, stroke and Alzheimer’s. It seems that over production of such molecules within the brain itself can damage neurons - particularly certain cytokines.
85
working memory brain regions
frontal and pareital lobes (auditory parts are lateralized to the left)
86
long term memory brain regions
Long-term memory is also sub-divided into different systems located in widely dispersed networks of the brain. The different networks do very different jobs. Broadly speaking, information enters sensory systems and then passes down pathways that provide increasingly specialised processing.
87
visual memory path
information entering the visual system passes down a so-called ventral pathway from the striate cortex to the medial temporal lobe through a cascade of networks that work out shape, colour, object dentity, whether the object is familiar or not, until finally, some kind of memory is formed of this particular object and when and where it has been seen.
88
episodic memory brain regions
the perirhinal cortex which mediates the sense of familiarity about the past and the hippocampus which encodes events and places.
89
semantic dementia
type of Alzheimer's. Early on, patients will be quite capable of telling you that the pictures they are being shown in an experiment are of a cat, or a dog, or of a car, or a train. Later on in the disease, they may hesitate to call a picture of a mouse a mouse, saying instead that it is a dog. What this confirms is that factual information is organised categorically, with animate information stored together in one place well away from inanimate information.
90
Baddeley
Alan Baddeley who developed the idea of working memory, which consists of a number of different interacting systems.
91
dyslexia rate
As many as 1 in 10 of us may have had this | condition
92
control of reading
Visual control of the eye movement system is dominated by a network of large neurons known as the magnocellular system. It gets this name because the neurons (cells) are very large (magno). It is specialised to respond particularly well to moving stimuli and it is therefore important for tracking moving targets.
93
dyslexics vs normal readers
- impaired visual magnocellular system - less steady control of the eye - altered patterns of function activation in brain regions sensitive to visual motion (poor sensitivity to visual motion)
94
dyslexia types
different forms of the acquired condition, known as surface and deep dyslexia, which may require different kinds of treatment.
95
4 dyslexics mentioned
Leonardo da | Vinci, Hans Christian Andersen, Edison and Einstein
96
Watkins
``` Jeffery Watkins a medicinal chemist who transformed the study of excitatory transmission in the brain by developing drugs like AP5 (below) that act on specific glutamate receptors ```
97
neuromodulator release and states of mind
- acetyclholine: during heightened attention | - dopamine, noradrenaline, steroid hormones (such as cortisol): novelty, stress, anxiety
98
NMDA receptor situation 1
If the synapse is activated quite slowly (glutamate binding to NMDA receptors), the NMDA receptors play little or no role. This is because as soon as NMDA receptors open their ion channels these channels become plugged by another ion present in the synapse – magnesium (Mg2+).
99
NMDA receptor situation 2
But, when synapses are activated by several pulses very quickly to a set of inputs on to a neuron, the NMDA receptors immediately sense this excitement. This greater synaptic activity causes a large depolarisation in the postsynaptic neuron and this dispels the Mg2+ from the NMDA ion channels by a process of electrical repulsion. NMDA receptors are then immediately able to partake in the synaptic communication.
100
how do neurons partake in synaptic communication?
the postsynaptic neurons' NMDA receptors do this in 2 ways: first, and just like AMPA receptors, they conduct Na+ and K+ which adds to the depolarisation; second, they allow calcium (Ca2+) to enter the neuron. In other words, NMDA receptors sense strong neuronal activity and send a signal to the neuron in the form of a surge of Ca2+.
101
length of Ca2+ surge
This Ca2+ surge is also brief, lasting for no more than about a second while glutamate is bound to NMDA receptors.
102
Blakemore
``` Colin Blakemore has contributed to understanding how the visual system develops. This includes pioneering studies using cell-culture to study interactions between different parts of a pathway in the embryonic brain. ```
103
how many genes in the genome
40,000
104
zebrafish adv
The zebrafish embryo is transparent - allowing each cell to be watched under the microscope as it develops.
105
mouse adv
The mouse breeds rapidly - its genome has been | mapped and almost completely sequenced.
106
chick adv
less amenable to genetic studies, but their large embryos allow microsurgical manipulations - such as examining what happens when cells are moved to abnormal positions.
107
frog adv
less amenable to genetic studies, but their large embryos allow microsurgical manipulations - such as examining what happens when cells are moved to abnormal positions.