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Question 1

The nervous system consists of__. It is made up of __.

Answer 1

The nervous system consists of the brain, spinal cord and
peripheral nerves. It is made up of nerve cells, called
neurons, and supporting cells called glial cells.

Question 2

There are three main kinds of neurons

Answer 2

sensory, motor, interneurons

Question 3

The receptors sensitive to changes in ___ subserve the sensory
modalities of vision, hearing, touch, smell and taste.

Answer 3

The receptors sensitive to changes in light,
sound, mechanical and chemical stimuli subserve the sensory
modalities of vision, hearing, touch, smell and taste.

Question 4

The brain and spinal cord are connected to __ through __

Answer 4

The brain and spinal cord are connected to sensory
receptors and muscles through long axons that
make up the peripheral nerves.

Question 5

These basic structures of the nervous system are the same

in all vertebrates. What distinguishes the human brain is __. This is due to __

Answer 5

These basic structures of the nervous system are the same
in all vertebrates. What distinguishes the human brain is its
large size in relation to body size. This is due to an enormous
increase in the number of interneurons over the course of
evolution, providing humans with an immeasurably wide choice
of reactions to the environment.

Question 6

The brain consists of __

Answer 6

The brain consists of the brain stem and the cerebral

hemispheres.

Question 7

The brain stem is divided into __

Answer 7

The brain stem is divided into hind-brain, mid-brain and a

‘between-brain’ called the diencephalon.

Question 8

The diencephalon is divided into __

Answer 8

The diencephalon is divided into two very different areas

called the thalamus and the hypothalamus

Question 9

The cerebral hemispheres consist of __

Answer 9

The cerebral hemispheres consist of a core, the basal
ganglia, and an extensive but thin surrounding sheet of
neurons making up the grey matter of the cerebral cortex.

Question 10

The different parts of a neuron are __. The dendrites __, and the
axons __

Answer 10

The different parts of a neuron are in constant motion, a
process of rearrangement that reflects its own activity and
that of its neighbours. The dendrites change shape,
sprouting new connections and withdrawing others, and the
axons grow new endings as the neuron struggles to talk a bit
more loudly, or a bit more softly, to others.

Question 11

Inside neurons are __. These

consist of __

Answer 11

Inside neurons are many inner compartments. These
consist of proteins, mostly manufactured in the cell body,
that are transported along the cytoskeleton

Question 12

Most of the synapses on cells in the __ are located on the __ that
stick out like __.

Answer 12

Most of the synapses on cells in the cerebral cortex are located on the dendritic spines that
stick out like little microphones searching for faint signals.

Question 13

The axons of neurons __. These travel along __ rather like __. This works because __. When channels open, the Na+ or K+ ions flow down __, in and out of the cell, in response to __ of the membrane.

Answer 13

(3 Na+ out for every 2 K+ in)
The axons of neurons transmit electrical pulses called action potentials. These travel along nerve fibres rather like a wave travelling down a skipping rope. This works because the axonal membrane contains ionchannels, that can open and close to let through electrically charged ions. When channels open, the Na+ or K+ ions flow down opposing chemical and electrical gradients, in and out of the cell, in response to electrical depolarisation of the membrane.

Question 14

When __ stimuli to the __
exceed a certain intensity, they can cause __
and __

Answer 14

When mechanical, thermal or chemical stimuli to the skin
exceed a certain intensity, they can cause tissue damage
and a special set of receptors called nociceptors are
activated; these give rise both to protective reflexes and to
the sensation of pain

Question 15

The pathways from the __ to the __ and
from __ to the __ __. Thus movements of the right side of the body are
controlled by the left side of the cortex (and vice versa).
Similarly, the left half of the body sends sensory signals to
the __ such that, for example, sounds in the
left ear mainly reach the right cortex.

Answer 15

The pathways from the sensory receptors to the cortex and
from cortex to the muscles cross over from one side to the
other. Thus movements of the right side of the body are
controlled by the left side of the cortex (and vice versa).
Similarly, the left half of the body sends sensory signals to
the right hemisphere such that, for example, sounds in the
left ear mainly reach the right cortex.

Question 16

When the dendrite receives __, __. These are usually __, or they may be
__. All these
positive and negative waves of current are accumulated in
the dendrites and they spread down to the __. If they
don’t add up to very much activity, __. However, if the currents
add up to a value that crosses a threshold, __.

Answer 16

When the dendrite receives one of the chemical messengers
that has been fired across the gap separating it from the
sending axon, miniature electrical currents are set up inside
the receiving dendritic spine. These are usually currents
that come into the cell, called excitation, or they may be
currents that move out of the cell, called inhibition. All these
positive and negative waves of current are accumulated in
the dendrites and they spread down to the cell body. If they
don’t add up to very much activity, the currents soon die
down and nothing further happens. However, if the currents
add up to a value that crosses a threshold, the neuron will
send a message on to other neurons.

Question 17

When an action potential starts at the __, the first
channels to open are __ channels. A pulse of __ ions
flashes into the cell and __ is established
within a __. In a trice, the transmembrane voltage
switches by about __ mV. It flips from an inside membrane
voltage that is negative (about __ mV) to one that is
positive (about __ mV). This switch opens __ channels,
triggering a pulse of __ ions to flow out of the cell,
almost as rapidly as the __ ions that flowed inwards, and
this in turn causes __. The actionpotential
is over within less time than it takes to flick a
domestic light switch on and immediately off again.

Answer 17

When an action potential starts at the cell body, the first
channels to open are Na+ channels. A pulse of sodium ions
flashes into the cell and a new equilibrium is established
within a millisecond. In a trice, the transmembrane voltage
switches by about 100 mV. It flips from an inside membrane
voltage that is negative (about -70 mV) to one that is
positive (about +30 mV). This switch opens K+ channels,
triggering a pulse of potassium ions to flow out of the cell,
almost as rapidly as the Na+ ions that flowed inwards, and
this in turn causes the membrane potential to swing back
again to its original negative value on the inside. The actionpotential
is over within less time than it takes to flick a
domestic light switch on and immediately off again

Question 18

Remarkably few ions traverse the cell membrane to do this,
and the concentrations of Na+ and K+ ions within the
cytoplasm do not change significantly during an action
potential. However, in the long run, __ by __ whose job is to __. This happens in much the same way that a small leak in
the hull of a sailing boat can be coped with by baling out
water with a bucket, without impairing the overall ability of
the hull to withstand the pressure of the water upon which
the boat floats.

Answer 18

Remarkably few ions traverse the cell membrane to do this,
and the concentrations of Na+ and K+ ions within the
cytoplasm do not change significantly during an action
potential. However, in the long run, these ions are kept in
balance by ion pumps whose job is to bale out excess sodium
ions. This happens in much the same way that a small leak in
the hull of a sailing boat can be coped with by baling out
water with a bucket, without impairing the overall ability of
the hull to withstand the pressure of the water upon which
the boat floats.

Question 19

Much of this has been known for 50 years based on
wonderful experiments conducted using __. The __ enabled
scientists to __

Answer 19

Much of this has been known for 50 years based on
wonderful experiments conducted using the very large
neurons and their axons that exist in certain
sea-creatures. The large size of these axons enabled
scientists to place tiny electrodes inside to measure the
changing electrical voltages.

Question 20

An analogy that might help you think about the conduction
of action potentials is the movement of energy along a
firework sparkler after it is lit at one end. The first ignition
triggers very rapid local sparks of activity (equivalent to __), but the overall progression of the sparkling
wave spreads much more slowly.

Answer 20

An analogy that might help you think about the conduction
of action potentials is the movement of energy along a
firework sparkler after it is lit at one end. The first ignition
triggers very rapid local sparks of activity (equivalent to the
ions flowing in and out of the axon at the location of the
action potential), but the overall progression of the sparkling
wave spreads much more slowly.

Question 21

synaptic vesicles reform when

Answer 21

Synaptic vesicles reform when
their membranes are swallowed back up into the nerve ending
where they become refilled with neurotransmitter, for
subsequent regurgitation in a continuous recycling process.

Question 22

how are neurotransmitters cleared from the synapse?

Answer 22

1) Glial cells are also lurking all around the synaptic cleft. Some of these have miniature
vacuum cleaners at the ready, called transporters, whose
job is to suck up the transmitter in the cleft. This clears the
chemical messengers out of the way before the next action
potential comes. But nothing is wasted - these glial cells
then process the transmitter and send it back to be stored
in the storage vesicles of the nerve endings for future use.
2) Sometimes the nerve cells pump the transmitter molecules
back directly into their nerve endings.
3) In other cases, the
transmitter is broken down by other chemicals in the
synaptic cleft.

Question 23

Typically, __
converge on a neuron and, at any one moment, some are
active and some are not. If __, __ and signals are passed down the axon of the receiving neuron.

Answer 23

Typically, a large number of synapses
converge on a neuron and, at any one moment, some are
active and some are not. If the sum of these epsps reaches
the threshold for firing an impulse, a new action potential is
set up and signals are passed down the axon of the receiving
neuron

Question 24

When a neurotransmitter is
recognised and bound by a metabotropic receptor, __. Binding of the
transmitter to a metabotropic recognition site can
be compared to an ignition key. It doesn’t __, as ionotropic receptors do, but
instead __. The metabolic engine of the neuron then revs up and
gets going.

Answer 24

When a neurotransmitter is
recognised and bound by a metabotropic receptor, bridging
molecules called G-proteins, and other membrane-bound
enzymes are collectively triggered. Binding of the
transmitter to a metabotropic recognition site can
be compared to an ignition key. It doesn’t open a door for ions in the membrane, as ionotropic receptors do, but
instead kick-starts intracellular second messengers into
action, engaging a sequence of biochemical events. The metabolic engine of the neuron then revs up and
gets going.

Question 25

The effects of neuromodulation include __. These changes are __ and __ than those triggered by the __ and their effects __.

Answer 25

The effects of neuromodulation include changes in ion channels, receptors, transporters and even the expression of genes. These changes are slower in onset and more long-lasting than those triggered by the excitatory and inhibitory transmitters and their effects extend well beyond the synapse.

Question 26

Among the many messengers acting on G-protein coupled receptors are __. Neurons that release these transmitters not only __, but their anatomical organisation is also remarkable because __. These neuromodulatory transmitters do not __, but __

Answer 26

Among the many messengers acting on G-protein coupled receptors are acetylcholine, dopamine and noradrenaline. Neurons that release these transmitters not only have a diverse effect on cells, but their anatomical organisation is also remarkable because they are relatively few in number but their axons project widely through the brain. These neuromodulatory transmitters do not send out precise sensory information, but fine-tune dispersed neuronal assemblies to optimise their performance.

Question 27

Drugs differ in their dependence | liability - ranging from high risk in the case of __ to lower risk in the case of __.

Answer 27

Drugs differ in their dependence liability - ranging from high risk in the case of cocaine, heroin and nicotine to lower risk in the case of alcohol, cannabis, ecstasy and amphetamines.

Question 28

physical effects of cannabis

Answer 28

Cannabis is an intoxicant which can be pleasurable and relaxing, and it can cause a dream-like state in which one’s perception of sounds, colours and time is subtly altered. No-one seems to have died from an overdose, although some users may experience unpleasant panic attacks after large doses.

Question 29

amphetamines and neurotransmitters

Answer 29

These drugs act in the brain by causing the release of two naturally occurring neurotransmitters. One is dopamine - which probably explains the strong arousal and pleasurable effects of amphetamines. The other is serotonin - which is thought to account for their ability to cause a sense of well-being and a dream-like state that can include hallucinations. Dexedrine and Speed promote mainly dopamine release, Ecstasy more serotonin. The even more powerful hallucinogen d-LSD also acts on serotonin mechanisms in the brain.

Question 30

Arrays of receptors throughout our bodies are tuned to different aspects of the somatosensory world – __ - with yet others for the sensations of pain.

Answer 30

touch, temperature | and body position

Question 31

Embedded in the dermal layers of the skin, beneath the surface, are several types of tiny receptors. Named after the scientists who first identified them in the microscope, __ sense different aspects of touch. All these receptors have __ that __ in response to __, triggering __ that can be recorded experimentally by __. Some amazing experiments were conducted some years ago by scientists who experimented on themselves, by __.

Answer 31

Embedded in the dermal layers of the skin, beneath the surface, are several types of tiny receptors. Named after the scientists who first identified them in the microscope, Pacinian and Meissner corpuscles, Merkel’s disks and Ruffini endings sense different aspects of touch. All these receptors have ion channels that open in response to mechanical deformation, triggering action potentials that can be recorded experimentally by fine electrodes. Some amazing experiments were conducted some years ago by scientists who experimented on themselves, by inserting electrodes into their own skin to record from single sensory nerves.

Question 32

which subsurface dermal receptors respond best to what?

Answer 32

Pacinian and Meissner corpuscles: adapt quickly and so respond best to rapidly changing indentations (sense of vibration and flutter). Merkel's disks: responds well to a sustained indentation of the skin (sense of pressure) Ruffini endings: respond to slowly changing indentations.

Question 33

``` Once they detect a stimulus, the receptors in turn __. The __ connecting __ to the __ are __ that convey information from the __ towards the __ extremely rapidly ```

Answer 33

Once they detect a stimulus, the receptors in turn send impulses along the sensory nerves that enter the dorsal roots of the spinal cord. The axons connecting touch receptors to the spinal cord are large myelinated fibres that convey information from the periphery towards the cerebral cortex extremely rapidly

Question 34

__, __ and __ (stmuli) are detected by __ with __, which transmit more __. Temperature receptors also show __

Answer 34

Cold, warmth and pain are detected by thin axons with “naked” endings, which transmit more slowly. Temperature receptors also show adaptation

Question 35

``` There are relay stations for touch in the __ and the __, before projection on to the __ in the __ called the __ cortex. The nerves cross the midline so that __ ```

Answer 35

There are relay stations for touch in the medulla and the thalamus, before projection on to the primary sensory area in the cortex called the somatosensory cortex. The nerves cross the midline so that the right side of the body is represented in the left hemisphere and the left in the right.

Question 36

Skin is sensitive enough to | measure

Answer 36

a raised dot that is less than 1/100th of a millimetre high – provided you stroke it as in a blind person reading Braille.

Question 37

Functional brain imaging suggests that the identification of textures or of objects by touch involves

Answer 37

diff regions of cortex

Question 38

Molecular biological techniques have now revealed the structure and characteristics of a number of nociceptors. They include receptors that respond to (3)

Answer 38

heat above 460 C, to tissue acidity and - again a surprise - to the active ingredient of chilli peppers.

Question 39

Two classes of | peripheral afferent fibres respond to noxious stimuli:

Answer 39

relatively fast myelinated fibres, called Αδ fibres, and very fine, slow, non-myelinated C fibres.

Question 40

the pathway for the emotional aspect of pain projects to quite different areas than the somatosensory cortex, including

Answer 40

the anterior cingulate | cortex and the insular cortex.

Question 41

which brain imaging technique was used to study pain sensation vs pain 'unpleasantness'?

Answer 41

PET

Question 42

during changes in experienced pain intensity there was activation of the __, whereas the experience of pain unpleasantness was accompanied by activation of the __.

Answer 42

during changes in experienced pain intensity there was activation of the somatosensory cortex, whereas the experience of pain unpleasantness was accompanied by activation of the anterior cingulate cortex.

Question 43

Light enters the eye through the __ and is focused, by the __ and the __, on to the __ at the back of the eye. The pupil is surrounded by __

Answer 43

Light enters the eye through the pupil and is focused, by the cornea and the lens, on to the retina at the back of the eye. The pupil is surrounded by a pigmented iris that can expand or copntract, making the pupil larger or smaller as light levels vary.

Question 44

If overexposed | to one colour of light,

Answer 44

the pigments in the cones adapt and then make a lesser contribution to our perception of colour for a short while thereafter

Question 45

3 Rs

Answer 45

reduction, refinement, replacement

Question 46

what happens during seizures?

Answer 46

there is an increase in the firing of action potentials by neurons followed by a period of reduced excitability. This cyclical process is modulated by inhibitory (GABA) and excitatory (glutamate) neurotransmitters. When the reduction in excitability is incomplete, seizures may be triggered by the uncontrolled recruitment of neighbouring neurons. This recruitment may be localised (causing a partial seizure), or may spread to the entire cortex (a generalized seizure). `

Question 47

In people with epilepsy, | attacks may be provoked by

Answer 47

tiredness, missed meals, low | blood sugar, alcohol, or flickering television screens.

Question 48

Very occasionally - especially if the headache __, or is associated with a __ or with ___ – there can be a serious underlying cause.

Answer 48

Very occasionally - especially if the headache comes on very quickly, or is associated with a skin rash or with vomiting – there can be a serious underlying cause.

Question 49

a migraine is characterized by

Answer 49

``` migraine is common cause of headache. As well as a sore head (often on one side), people feel sick, find bright lights or loud noises discomforting, and experience a migrainous aura consisting of flashing lights or jagged lines. The aura generally precedes the headache. ```

Question 50

how is fuel delivered to neurons and glia?

Answer 50

That fuel is delivered through the four major blood vessels that supply the brain. The most important fuels are oxygen, and carbohydrate in the form of glucose; together these provide the raw materials to make ATP - the energy currency of cells. This energy is necessary for driving the flow of charged ions that underlie the electrical activity of neurons.

Question 51

TIA

Answer 51

transient ischaemic attack. the blood supply to a part of the brain fails and the supply of ATP is interrupted. Neurons cannot recharge their ionic gradients and so can no longer conduct action potentials. If the obstruction passes quickly, neurons can again make ATP, recharge their membranes and normal function will resume. Fortunately, no permanent damage occurs in TIA.

Question 52

Doctors have long recognised and diagnosed brain disease according to the region affected. For many diseases, the name is

Answer 52

a description of what appears to be wrong and the part of the brain involved, often dressed up in Latin or Greek, such as “parietal apraxia”.

Question 53

Multiple sclerosis is caused by

Answer 53

inflammation in the nervous | system that flares up and then settles down again.

Question 54

If the immune system attacks the myelin that wraps | around neurons,

Answer 54

there will be a local area of inflammation | that causes demyelination.

Question 55

Some early onset forms of Parkinson’s | disease are due to

Answer 55

problems in genes coding for Parkin.

Question 56

``` genetics has provided a handle to get us started in understanding Alehzimer's – pointing to mutations in genes that encode (2) ```

Answer 56

amyloid precursor protein (from which amyloid is made) and the presenilins (which encode enzymes that break the precursor protein down).

Question 57

when chronically activated, stress hormones may actually | damage brain cells, particularly in which regions?

Answer 57

the frontal and temporal | lobes of the brain

Question 58

It has recently been found that | antidepressant drugs promote

Answer 58

the integrity of brain cells and increase the rate at which new neurons are produced in the hippocampus.

Question 59

what is happening as Alzheimer's develops?

Answer 59

brain cells die, the cortex things, the ventricles (fluid-filled spaces in the brain) enlarge

Question 60

core symptoms of shcizophrenia

Answer 60

delusions (abnormal beliefs – commonly bizarre ideas which are often persecutory in nature) and hallucinations (disorders of perception where sufferers experience abnormal sensory impressions).

Question 61

what have post-mortem studies revealed about schizophrenia?

Answer 61

the way that neurons have connected up during development may be abnormal, and that other neurotransmitter systems, such as glutamate, may be malfunctioning

Question 62

last great frontier

Answer 62

Our efforts to understand the nature of mental disorders | represents the last great frontier for medical neuroscience.

Question 63

phrenologists

Answer 63

thought they could understand the brain by | examining the bumps on the surface of the skull.

Question 64

Structural brain imaging techniques began to be developed how long ago?

Answer 64

30 yr ago

Question 65

Our brain contains roughly __ nerve cells, __ of ‘wires’, __ connections, all packed into a volume of __, but weighing only __ and consuming a mere __. If we tried to build such a brain using silicon chips, it would consume about __, i.e. enough electricity to __

Answer 65

Our brain contains roughly 100 billion nerve cells, 3.2 million kilometers of ‘wires’, a million-billion connections, all packed into a volume of 1.5 litres, but weighing only 1.5 kg and consuming a mere 10 watts. If we tried to build such a brain using silicon chips, it would consume about 10 megawatts, i.e. enough electricity to power a town.

Question 66

However, compared to the speed of | digital computers, the speed of nerve impulses is

Answer 66

very | slow - only a few metres per second.

Question 67

__. In this way, silicon engineers can begin to emulate the connectivity of biological networks.

Answer 67

the impulses from many silicon neurons can be ‘multiplexed’ - a process of carrying many different messages along the same wire.

Question 68

how is the suprachiasmatic nucleus unusual?

Answer 68

(controls sleep cycle) just above optic chasm; the neurons here are unusual in having lots of synapses btwn their dendrites to synchronize their firing together

Question 69

If people are woken during REM sleep,

Answer 69

they almost | invariably report dreaming.

Question 70

how many episodes of REM sleep do we have?

Answer 70

In fact, most of us will have about 4 to 6 short episodes of REM sleep each night. Babies have a bit more REM sleep and even animals show REM sleep. .

Question 71

how do clock prteins work?

Answer 71

mRNA and protein synthesis begins early in the day, the proteins accumulate, link up together and this linkage then stops their own synthesis. Daylight helps to degrade the proteins whose level eventually drops to a point where the genes that make PER and TIM protein get going again.

Question 72

Our defences work in many ways. The first

Answer 72

is locally within the tissue that is infected, injured or inflamed, causing swelling, pain, changes in blood flow and release of local inflammatory molecules.

Question 73

The brain receives signals from injured or infected tissues | that may be __ or __ in origin. Neural signals seem to be via

Answer 73

neural or humoral (via circulating molecules) in origin. C-fibers vagus nerve from the liver

Question 74

signals from injured/infected tissues from the brain include

Answer 74

prostaglandins (which are inhibited by aspirin), and complement proteins (a cascade of proteins important in killing invader cells); most important signals are cytokines

Question 75

heat-shock proteins

Answer 75

special molecules called heat-shock proteins guide damaged proteins to where they can be repaired or harmlessly degraded, thus protecting cells from toxicity or dysfunction.

Question 76

in severe depression __ is over-produced and recent work suggests that the __ also shrinks in this condition.

Answer 76

in severe depression cortisol is over-produced and recent work suggests that the hippocampus also shrinks in this condition.

Question 77

Anti-depressant | drugs often help to normalise

Answer 77

the overactive HPA axis. One idea is that they do so, in part, by adjusting the density of MR and GR receptors in the brain, particularly in the hippocampus.

Question 78

MRI images

Answer 78

are very fine-grained.

Question 79

How did working-memory evolve?

Answer 79

Studies with young children point to a critical role for workingmemory in learning language, suggesting that this memory system may have co-evolved with speech. The precision required for keeping track of words and their order in a sentence is critical for accurately working out the correct meaning.

Question 80

Downstream of the receptors activated during | imprinting or the tasting of food,

Answer 80

a cascade of secondmessenger chemicals transmit signals to the nucleus of brain cells where genes are activated to make special proteins that can literally fix the memory.

Question 81

How are space maps and other memory traces formed?

Answer 81

One emerging view is that synaptic plasticity based on NMDA receptors is involved. Learning about places is impaired when a drug that blocks NMDA receptors is applied to the hippocampus.

Question 82

Having said that, really serious forgetfulness might be | alleviated by drugs that

Answer 82

make NMDA or AMPA receptors work better, or drugs to stimulate the cascade of secondmessenger signals that studies of learning in young animals have identified.

Question 83

When researchers put experienced taxi drivers in a brain scanner and asked them to imagine a trip from Marble Arch to Elephant and Castle, they saw greater activation in the

Answer 83

right | parahippocampal cortex

Question 84

It may only have been __ ago that communities in scattered parts of the world realised that the thousands of spoken words are made up of a smaller number of separate sounds (__ in English) and that these can be represented by an even smaller number of visual symbols.

Answer 84

It may only have been a thousand years ago that communities in scattered parts of the world realised that the thousands of spoken words are made up of a smaller number of separate sounds (44 phonemes in English) and that these can be represented by an even smaller number of visual symbols.

Question 85

reading depends on (2)

Answer 85

- orthography | - hearing the separate sounds in words in their right order``

Question 86

what exactly do dyslexics have problems with

Answer 86

What the eyes see has to be integrated with motor signals from the eye movement system; and it is with this visuomotor integration that many dyslexics have problems.

Question 87

motion error signal

Answer 87

impt feature of magnocellular system. it generates motion signals, during reading, when the eyes move off letters they are meant to be fixating. This motion error signal is fed back to the eye-movement system to bring the eyes back on target.

Question 88

It is important to stress that dyslexics may be slightly | better than even good readers at

Answer 88

some perceptual judgements such as colour distinctions and global, rather than local, shape discriminations

Question 89

There are various | mechanisms of plasticity, of which the most important is

Answer 89

synaptic plasticity – the science of how neurons alter their | ability to communicate with one another.

Question 90

Neuroscientists are particularly interested in long-lasting | changes in synaptic strength that can be produced by

Answer 90

brief periods of neuronal activity, notably in two processes called long-term potentiation (LTP), which enhances their strength, and long-term depression (LTD), which depresses them.

Question 91

AMPA receptors

Answer 91

are fastest into the act. Once glutamate is bound to these receptors, they rapidly open their ion channels to produce a transient excitatory postsynaptic potential. The glutamate is only bound to AMPA receptors for a fraction of a second and, once it leaves and is removed from the synapse, the ion channels close and the electrical potential reverts to its resting state. This is what happens when neurons in the brain send information to each other quickly.

Question 92

what's the result of NMDA receptor activation?

Answer 92

it triggers plastic changes in the connectivity of neurons

Question 93

Changes in the functioning of AMPA receptors are not the whole story. As memories become more permanent, structural alterations occur in the brain:

Answer 93

Synapses with more AMPA receptors inserted following the induction of LTP change their shape and may grow bigger, or new synapses may sprout out from the dendrite so that the job of one synapse can now be done by two. Conversely, synapses that lose AMPA receptors following the induction of LTD may wither and die.

Question 94

how is muscle movement cotrolled?

Answer 94

the axons of motor neurons project out and form specialized contacts w/ individual muscle fibers at the neuromuscular junction. Each action potential in a motor neuron causes the release of neurotransmitter (ACh) from nerve endings and generates a corresponding action potential in the muscle fibres. This causes Ca2+ ions to be released from intracellular stores inside each muscle fibre. This in turn triggers contraction of the muscle fibres, producing force and movement.

Question 95

Here is a complete map of the body: nerve cells that cause movements in different limbs (via connections onto the motor neurons in the spinal cord) are topographically arranged. By using a recording electrode, neurons may be found in any part of this map that are active about __ before activity in the appropriate muscles

Answer 95

100 milliseconds

Question 96

where exactly is the problem in Parkinson's?

Answer 96

The problem is the degeneration of neurons in an area of the brain called the substantia nigra (so-called because it is black in appearance) whose long, projecting axons release the neurotransmitter dopamine into the basal ganglia .

Question 97

Amazingly, many of our genes are shared with

Answer 97

fruit fly Drosophila

Question 98

Neuroscientists studying brain development examine a wide | variety of animals:

Answer 98

zebrafish, frog, chick and mouse