Download 6p - Ping Pong

Biomed T4
Neurovetenskap – Tentamen – VT99
1999-03-03 kl 9-14
Tema 1: Aktionspotentialen (6p)
Nervceller mottager synaptiskt inflöde på flera olika ställen på dendriterna. Vid repetitiv fyrning
av de presynaptiska neuronen kommer storleken på svaret i det postsynaptiska neuronet att
bestämmas av både den spatiala och den temporala summationen.
a) Beskriv mekanismerna för temporal resp spatial summation med hjälp av specifika exempel.
(2p)
b) Vilken membranegenskap är bestämmande för den temporala resp spatiala summationen? (1p)
c) Nervceller kan fyra av aktionspotentialer repetitivt antingen spontant eller som svar på en
experimentellt injicerad depolariserande ström. Beskriv de jonmekanismer som ligger bakom
aktionpotentialen samt några mekanismer vilka kan modulera nervcellernas fyrningsfrekvens.
(3p)
Tema 2: Frisättning av transmittorsubstans från den presynaptiska
terminalen (6p)
a) Varför behövs en depolarisering av terminalens membran för att aktivera frisättningen av
transmittor? (2p)
b) Vilka skillnader finns i bildningen av olika typer av synaptiska vesikler? (2p)
c) Vilka kategorier av transmittorer är kända i CNS? Ge ett specifikt exempel för varje typ. (2p)
Tema 3: Ett patch clamp-experiment på jonkanaler (6p)
a) Du gör ett patch clamp-experiment där du har 10 M glutamat i din patch-pipett. Du ser två
sorters jonkanaler (en liten och en stor). När du gör samma experiment men utan glutamat
ser du inga kanaler i din patch. Du provar då att skölja cellen med 10 M glutamat, samtidigt
som du inte har någon glutamat i pipetten. Då ser du den lilla kanalen men inte den stora
kanalen. Båda kanalerna är tydligen glutamataktiverade, men vilken är ionotropisk och
vilken är aktiverad av en metabotropisk receptor? Motivera svaren för bägge kanalerna. (4 p)
Observera att glutamat inte kan läcka in eller ur pipetten när man har ett GigaOhm seal.
b) När du kollar reverseringspotentialen för de två kanalerna, så är den -90 mV för den lilla och
0 mV för den stora kanalen. Vilka joner går troligtvis genom kanalerna? Hur kan du
kontrollera att du har rätt (designa ett enkelt experiment)? (2 p)
Tema 4: Utvecklingen av storhjärnans cortex (6p)
Denna fråga behandlar cortex cerebri som modell för nervsystemets utveckling.
a) Var bildas de cortikala neuronen? (1p)
b) Hur når neuronen sin slutliga position i cortex? (1p)
c) Nämn minst två regressiva faktorer som är inblandade i utvecklingen av cortex. (2p)
d) Beskriv kort minst två faktorer som är viktiga för den regionala specialiseringen av cortex
cerebri. (2p).
Biomed T4
Neurovetenskap – Tentamen – VT99
1999-03-03 kl 9-14
Tema 5: Primära synbarken (6p)
Högre synfunktioner och medvetna synsensationer styrs från visuella areor i cortex. Den primära
synbarken (V1) i nackloben mottar den största delen av det retinala inflödet, via laterala
knäkroppen i thalamus, och projicerar sedan vidare till högre synareor.
a) Primär synbark är visuotopiskt organiserad. Vad menas med detta? (1p)
b) En karaktäristisk celltyp i primär synbark är ‘simple cell’. Vilken typ av stimuli ger typiskt en
maximal aktivering av en ‘simple cell’ ? (1p)
c) Primär synbark antas vara uppbyggd av så kallade hyperkolumner. Redogör med en
schematisk skiss för hur en hyperkolumn är uppbyggd, med förklaring av begreppen
orienteringsband, okulära dominansband samt ‘blobs’. Var noga med att ge tydliga förklaringar
till alla delar av bilden! (4p)
Tema 6: Smärta (6p)
Efter en hudskada uppkommer ömhet på själva skadeplatsen som anses bero på sensitisering av
perifera nervändslut till följd av frisättning av en rad inflammationsrelaterade substanser. Det
uppkommer även ofta hudöverkänslighet i huden som omger skadeplatsen, trots att man inte kan
påvisa inflammation där.
a) Vad kallas detta fenomen (1p)?
b) Var anser man att de processer äger rum som ger upphov till fenomenet (1p)?
c) Förklara de processer som ger upphov till fenomenet (2p)
d) Ge exempel på signalsubstanser och receptorer som anses involverade (2p).
Tema 7: Muskelreceptorer (6p)
Elektromyografi (EMG) används både inom grundforskning och på kliniken för att undersöka
motoriska funktioner och sjukdomstillstånd, t. ex. genom studier av reflexsvar orsakade genom
stimulering av olika muskelreceptorer.
a)
Nämn de två viktigaste typerna av muskelreceptorer och beskriv hur de är uppbyggda (2p).
b) Vilka typer av stimuli är dessa två typer av muskelreceptorer mest känsliga för? (1p)
c)
Förklara varför de reagerar olika när en muskel sträcks ut passivt, respektive kontraheras
aktivt (1p)
d) När en s. k. sträckreflex utlöses i en muskel reagerar nervsystemet genom att kontrahera
muskeln och dess synergister samtidigt som muskelns antagonister inhiberas. Beskriv
signalens väg från muskelreceptorn i fråga, via afferent till ryggmärgen, omkopplingar i
ryggmärgen till olika motorneuron kopplade till muskeln i sig och till dess antagonist. (2p)
Tema 8: Kontroll av lokomotionsrörelser (6p)
OBS: Besvara helst denna fråga på engelska; skulle dock språket vara ett hinder för Dig så
besvara frågan på svenska.
Detta tema behandlar de basala neurala mekanismerna för generering av gångrörelser.
a) Beskriv kort gångrörelsemönstret och stegcykelns olika faser (2p)
b) Ge en kort karakteristik av kontrollmekanismen för benets rörelser – lokalisation; hur benets
muskler kontrolleras så att en gångrörelse uppstår (2p)
c) Ange hur kontrollmekanismen aktiveras när gångrörelsen skall startas (1p)
d) Ange betydelsen av sensoriska signaler från benet under gångrörelsen (1p)
Biomed T4
Neurovetenskap – Tentamen – VT99
1999-03-03 kl 9-14
Tema 9: Initiering av viljemässiga rörelsemönster (6p)
Du skall utföra en väl inövad, viljemässig rörelse – Du skall skriva Din namnteckning. Du skall
här redogöra för hur nervsystemet initierar denna rörelse, från det att Du bestämt Dig för att
utföra den.
a) Beskriv kort hur CNS selekterar det rätta motorprogrammet för rörelsen (4p)
Basala ganglierna ansvarar för selektionen av rätt motoriskt program (1p)
Signaler från handens och fingrarnas motoriska cortexområden exciterar
motsvarande områden i basala gangliernas mottagande del – striatum (bibehållen
somatotopik genom basala ganglierna) (1p)
Direkta vägen genom basala ganglierna – rörelseutlösande – aktiveras och påverkar
via thalamus motorprogrammet för handens och fingrarnas rörelser i motorcortex
(1p)
Basala ganglierna verkar inhibitoriskt på thalamus (och hjärnstam). När direkta
vägen aktiveras lyfts inhibitionen tillfälligt av så att thalamusneuronen kan
aktiveras – rätt motorprogram kommer då att i sin tur aktiveras. (1p)
b) Från vilket cortexområde kontrolleras handens finmotorik och vad utmärker denna
descenderande kontroll, så att Du kan greppa pennan och styra den exakt när Du skriver
namnteckningen? (2p)
Primära motorcortex styr handens finmotorik (1p).
Den descenderande kontrollen är här monosynaptisk, med direkt förbindelse till
hand-/fingermuskulaturens motorneuron (1p).
Tema 10: Hur och varför vi sover (6p) ISB
Hjärnan tycks behöva sömnen. Beskriv kort:
a) De olika sömnstadierna och deras karakteristika under en normal natt (4p)
REM-nREM
1p
nREM 4 stadier
1p
stadiernas karaktär 1p
schematisk framställning av övergång mellan stadierna 0,5p
b) Varför sömnen behövs, dvs sömnens funktion (2p)
Vila, ‘rensa’, homeostas, utan konkretisering
Differentiering mellan betydelse hos REM, nREM
Immunoglobulinsyntes, hormonbalans
0,5p
0,5p
1p
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
Theme 1: The action potential (6p)
Neurons generate and conduct action potentials.
a) Describe the ionic mechanisms mediating the different phases of an action potential. 4p
Action potentials consist of different phases: rising phase, falling phase, fast AHP
and slow AHP. The rising phase is mediating by a massive influx of sodium through
voltage-gated channels, the falling phase is mediated by outflow of potassium ions
through voltage-gated channels at the same time the influx of sodium is stopped due
to inactivation of sodium channels. The fast AHP is due to activation of potassium
channels that tend to bring the membrane potential toward the equilibrium
potential for potassium. The slow AHP is due to activation of calcium-dependent
potassium channels. Calcium influx occurs due to the depolarization of the
membrane potential that opens voltage-gated calcium channels. The intracellular
calcium concentration increases and activation potassium channels sensitive to
calcium.
b) What mechanisms can be used to change the action potential frequency in neurons? 1p
The firing frequency can be modulated by changing the amplitude of the slow AHP
or by changing the membrane potential.
c) What factors can change the conduction velocity in neurons? 1p
The conduction velocity can be modified by two factors: the diameter of axons and
myelinization.
Theme 2: Postsynaptic mechanisms (6p)
Neurotransmitters exert their effects on cells by binding to and activating different types of
receptors. There are two major types of neurotransmitter receptors. Ligand gated ion channels
and G-protein coupled receptors.
1. Explain briefly how a typical ligand gated ion channel works (3p).
A ligand gated ion channel is a pentameric protein containig one or more binding
site(s) (receptor) for a neurotransmitter, and an ion channel. Binding of the
neurotransmitter to the receptor causes a conformational change which results in
the opening of the ino channel. Each of the five
subunit which compose a ligand-gated ion channel contains four transmembrane
spanning regions and the second transmembrane spanning region forms the walls of
the channel. Ligand gated ion channels such as the nicotinic acetylcholine receptor
and the glutamate receptors, are permeable to positively charged ions, and therefore
their activation would result in membrane depolarization. Ligand gated ion
channels such as the GABA receptor and the glycine receptor, are permeable to
negatively charged
ions, and therefore their activation would result in membrane hyperpolarization.
The selectivity of the channel to cations or anions is determined by an excess of
negative or positive charge within the channel.
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
The binding of a neurotransmitter to a G-protein coupled receptor causes the activation
of the receptor, which in turn activates a G-protein. The activated G-protein consists of an alpha
subunit complexed with GTP and of a beta-gamma dimer.
2. What reaction inactivates the G-protein (2p)?
The reaction which inactivates the G-protein is the hydrolysis of GTP to GDP+Pi.
The alpha subunit of the G-protein possesses GTPase activity and the active form of
the G-protein (alpha-GTP plus beta-gamma dimer) is inactivated by the reaction:
alpha-GTP ----> alpha-GDP+Pi.
3. What is the inactive form of the G-protein (1p)?
The inactive form of the G-protein is the trimeric form of the G-protein (alpha-betagamma) bound to GDP. The inactive form of the G-protein is formed following GTP
hydrolysis by the alpha subunit (see above).
Theme 3: Development of the nervous system (6p)
Describe the main events at the cellular level in the development of the cerebral cortex:
1. Proliferation (2p)
Proliferation occurs in the ventricular (and subventricular) zones. It the different
phases of the cell cycle (G1, S, G2, M) the cell body of the progenitor cell moves
radially within the VZ. Progenitor cells can divide symmetrically or
asymmmetrically. Symmetrical division gives raise to dividing progenitors,
asymmetrical division gives raise to one dividing progenitor and to one migrating
neuron. Symmetrical division increases the surface of the VZ, asymmetrical division
gives raise to the cerebral cortex, previous migration, formation of the cortical plate
etc. With time more and more VZ cells quit the cell cycle (stop dividing). Neurons
originating from the same precursor cell are called a clone.
2. Migration (2p)
Neurons migrate to their final position in the cortex by migrating along radial glia.
Radial glia is a cell of the astrocytic type with a cell body in the VZ and a process
reaching the surface of the brain. Migrating neurons have an elongated shape with a
leading process which will later become the apical dendrite and a trailing process
which will become an axon. Migration gives raise to and inside-out pattern of
neuronal birthdays with early generated neurons generally at the bottom (deep
layers) and recently generated neurons at the top (upper cortical layers).
3. Formation of connections (2p)
The formation of connections involves axonal elongation, axonal branching,
synaptogenesis, elimination of supernumerary axonal branches and synapses.
Axonal elongation is controlled by the activity of the growth cone (describe the GC).
GC behavior is controlled by gradients of diffusing molecules, substrate bound
molecules and probably by electrical fields. Molecules (name some ?) can have an
attractant or a repulsive action on the GC. The various steps involved in
synaptogenesis are incompletely known. Nevertheless a large body of data
implicates the role of activity in synaptic validation (candidate can describe the
Wiesel and Hubel work in the visual system).
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
Theme 4: Touch (6p)
This theme deals with the peripheral mechanisms underlying the sensation of touch to the skin.
1. Describe briefly the four types of non-nociceptive receptors found in non-hairy skin: their
response characteristics and what type of stimulus they detect. (4p)
The four types of non-nociceptive receptors in non-hairy skin:
Meissner’s corpuscles (phasic; 0.5 point), detect touch, pressure, and flutter
(0.5 point).
Merkels Discs (tonic; 0.5 point), tonic responses, detect light touch and pressure
(0.5 point).
Pacinnian corpuscles (phasic; 0.5 point), detect deep pressure and vibration
(0.5 point).
Ruffini corpuscles (tonic; 0.5 point), detect skin stretch and indentation (0.5
point).
2. How is the sensation of touch coded in the periphery? (2p)
The receptor potential, which is proportional to stimulus strength, generates
spikes in axons which then enter the central nervous system (1 point). Action
potential spiking gives rise to a frequency code that provides a measure of
the stimulus strength (0.5 point). The number of receptors stimulated and their
receptive fields allows coding of stimulus size and location (0.5 point).
Theme 5: Pain modulatory mechanisms (6p)
(More mechanisms can certainly be added to those below, but some of the important ones are
mentioned. Only two examples for each question are required)
Whether a stimulus will ultimately be perceived as pain or not depends on a number of
modulatory mechanisms acting at different levels along the sensory pathways. They may either
increase or decrease the afferent signals. Describe at least two such mechanisms (facilitatory or
inhibitory) believed to active at:
1) the peripheral injury site (2p),
Peripheral sensitisation can be mediated by several chemicals released from the
injured tissue or from local inflammatory cells: bradykinin, prostaglandines such as
PGE2 and PGI2, interleukin 1 (may increase the number of bradykinin receptors),
serotonine (by reducing the slow inhibitory after potential), histamine, nor
epinephrine. Peripheral "desensitisation" may arise from for example increase of
opioid receptors on peripheral nociceptive endings and release of enkephalin from
local cells in the injured tissue.
2) in the spinal cord and/or brainstem (2p)
Central sensitisation can be mediated by release in the dorsal horn of glutamate
acting on NMDA receptors, release of peptides such as substance P and calcitonin
gene related peptide (CGRP, may inhibit the break down of SP), and release of
BDNF which increases NMDA activity. Central "desensitisation" may arise from
local release of enkephalin and under certain circumstances from local release of
serotonin, nor epinephrine, GABA and glycine.
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
3) Describe the putative mechanisms of two clinically important ways to alleviate pain (2p).
Acetylsalicylic acid and related substances block the production of proinflammatory prostaglandines by inhibiting cyklo-oxygenases. Opiates such as
morphine may block nociceptive sensory transmission at different levels by acting
on opiate receptors. Transcutaneous nerve stimulation (TENS) may interfere with
the transmission of impulses in the dorsal horn and give rise to supraspinal release
of endogenous opioid substances acting on descending modulatory pathways.
Theme 6: Vestibular system (6p)
1. Indicate with a cross, for each variable below, whether the semicircular canals and/or the
macula organs, or neither of them, give information about it to the central nervous system.
Correct indications give 0.5p for each variable. (3p)
Semicircular canals
Macula (otolith) organs
X
The orientation of the head
in the gravity field
The orientation of the head
in relation to the body
X
Linear acceleration of the
head
Linear movement of the
head at constant speed
Angular (rotational)
acceleration of the head
X
Rotation of the head at
constant speed
2. Afferents from the vestibular organ reach the vestibular nuclei, and from there the information
is sent further to different targets in the central nervous system. 3p
Briefly describe the functional importance of vestibular projections to:
a) the spinal cord
E.g.: Postural corrections – integration of postural commands with locomotion.
Vestibular neck reflexes.
b) oculomotor centers in the brain stem
E.g.: Vestibulo-ocular reflex.
c) somatosensory cortex, via thalamus
E.g.: Conscious vestibular sensations.
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
Theme 7: Levels of motor control in the CNS (6p)
Describe the basic functional organization of the motor control system:
1) the three levels of motor control (1p),
The motor control system consists of three functional levels: the spinal cord, the
brainstem and the motor areas of cortex (primary, premotor and supplementary
motor cortex).
2) their hierarchical and parallel organization (3p),
The control levels are organized hierarchically: each level is not only responsible for
the generation of definite types of movements but also participates in the control of
movements generated by a
subordinary level through descending pathways. The motor control system has also
a parallel organization: each level controls movements through several pathways.
Their functions partly overlap.
3) the motor capacity of each level (2p).
The spinal cord is the lowest level of motor control. It is responsible for the
generation of
spinal reflexes (stretch reflex, flexion reflex e.g.) and for generation of rhythmical
motor patterns (locomotion, scratching). The brainstem is responsible for the
generation of some reflexes (swallowing, coughing, blinking), for eye movements
and for rhythmical motor patterns respiratory rhythm, chewing). In the brainstem,
a number of important motor centres are located (the centres for postural control,
the locomotor regions). Through the descending pathways (vestibulospinal,
reticulospinal, rubrospinal and tecto-spinal) the brainstem controls the movements
generated by the spinal cord. The motor areas of cortex are responsible for the
generation of voluntary movements. They also control the movements generated by
the spinal cord (through the corticospinal tracts and corticobulbospinal pathways)
and by the brainstem (through corticobulbar pathways).
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
Theme 8: Motor control: Neurons of the basal ganglia (6p)
This theme deals with the role played by the basal ganglia in motor control.
The input regions of the basal ganglia, that receive information from the cortex, contains two
main populations of neurons, each subserving a specific function in the basal ganglia circuitry.
1) Describe briefly each of the two neuron populations: cell type, main transmitter, connectivity
(i.e. projections to other basal ganglia regions), synaptic effect. 2p
Both populations (in striatum): medium spiny neurons (0.5p); main transmitter is
GABA, causing postsynaptic inhibition (0.5p).
One of the neuron populations has connections directly to the output regions of the
basal ganglia – globus pallidus interna (and substantia nigra pars reticulata); the
other population connects to globus pallidus externa (1p).
Each of the two neuron populations forms part of two separate pathways through the basal
ganglia. Activity in these two pathways results in different effects on the motor behaviour.
2) Name and describe the two pathways, and give a brief account for the mechanisms behind
their respective motor effect. 3p
The direct and indirect pathways (0.5p);
The direct pathway: Initiates, or augments, movements, while the indirect pathway
brakes or stops movements (0.5p);
The direct pathway initiates movement by inhibiting the neurons of the globus
pallidus interna (and substantia nigra pars reticulata), which then ceases to inhibit
the target neurons in the thalamus or brainstem (disinhibition).
The indirect pathway stops movement by inhibition of globus pallidus externa,
which then stops inhibiting nucleus subthalamicus. The neurons of this nucleus,
which are excitatory (glutamate) then start to excite the neurons of the globus
pallidus interna (and substantia nigra pars reticulata), leading to increased
inhibitory output onto the target neurons in the thalamus or brainstem (2p).
In Parkinsons´s disease, the dopamine neurons innervating the input regions of the basal ganglia
progressively die, leading to the typical motor disorder of this disease.
3) Explain how the loss of dopamine innervation of the two neuron populations (described
above) will cause the Parkinsonian motor disorder. 1p
The neurons of the direct pathway are normally excited by dopamine via D1
receptors, while the neurons of the indirect pathway are inhibited by dopamine via
D2 receptors. When in Parkinson´s disease the dopamine neurons progressively die,
the direct pathway will be less excited – decreasing the ability to initiate movements.
At the same time the indirect pathway will be less inhibited, which will further
brake the movements and diminish their amplitude (1p).
Biomed T4
Neuroscience – Final Exam – VT00
2000-02-29
Theme 9: Functions of the autonomic nervous system (6p)
The autonomic nervous system regulates a number of vital functions:
1. Give example of some functions that are regulated by the autonomic nervous system. 2p
Control of breathing, heart rate, blood pressure, sweating, etc
2. Which is the origin of the sympathetic nervous system? 1p
Cell bodies in the spinal cord intermediolateral columns via Th1-L2/3
(paravertebral ganglia) and prevertebral ganglia (ggl. coeliacum and mes. inf. +
sup.).
3. Which is the origin of the parasympathetic nervous system? 1p
N. III (oculomotorius), N. VII (facialis), N. IX (glossopharyngeus) and N. X (vagus)
and S2-S4 segments of the spinal cord.
4. When does an animal need the sympathetic nervous system? 1p
In ‘fight and flight’ reactions.
5. What is the fundamental difference between the sympathetic and parasympathetic nervous
system? 1p
In the sympathetic nervous system there are short preganglionic neurons and long
postganglionic neurons, whereas in the parasympathetic nervous, system, there are
long preganglionic and short postganglionic neurons. The sympathetic nervous
system is needed in ‘fight and flight’ reactions, shereas the parasympathetic nervous
system is needed in ‘rest and digest’ states.
Theme 10: Emotions (6p)
Emotions might be considered as subjective feelings expressed through physiological changes
and stereotyped motor responses.
1. By which system are the emotions physiologically expressed? (1p)
ANS
2. What is the name of the system that coordinates the emotional responses? (1p)
Limbic system
3. Describe how emotionality appears to be lateralized within the two cerebral hemispheres in
terms of two different aspects of emotional processing (4p)
1) Expression and comprehension of the affective aspect of speech.
The right hemisphere is responsible for prosody i e intonation/modulation of speech
whereas the corresponding area in the left hemisphere is more involved in
expression per se.
2) Establishment of mood.
The left hemisphere seems to be concerned with postitive, and the right with
negative emotions.
Biomed T4
Tentamen Neurovetenskap – VT01
2001-02-27
Tema 1: Nervcellen (8p)
Nervcellen kan funktionellt och morfologiskt delas upp i flera komponenter
a)
Rita en nervcell och märk ut dendriter, axon och kollatteral
2p
b)
Indikera på nervcellen vad som är mottagande del, axon hilloc (triggerzonen), fortledande
del och överförande del.
2p
c)
Beskriv kort flödet från receptoraktivering till frisättning av neurotransmittorer. Vad sker i
mottagande delen, axon hilloc (triggerzonen), fortledande delen och överförande delen. 4p
a) + b)
Dendriter
Mottagande del
Som
a
Axo
n
kollattera
l
Axon hilloc
Fortledande del
Överförande
del
c) Vid mottagardelen sker en receptoraktivering vilket kan ge en depolärisering som
passivt diffunderar i riktning mot axon hilloc. Om depoläriseringen är tillräckligt
stark vid axon hilloc uppstår en aktionspotential som fortleds genom axonet.
Aktionspotentialen aktiverar spänningsberoende Ca2+ kanaler vid presynapsen.
Ca2+ påverkar synaptiska vesikler att fusera med cellmembranet och frisätta
neurotransmittorer.
Tema 2 Jonkanaler (6p) – FACIT SAKNAS!
a)
What is an ion channel? (1p)
b)
What determines the direction of the flux of ions through an ion channel? (1p)
c)
What are the two main classes of ion channels? (1p)
d)
What is the function of the two classes of ion channels? (1p)
e)
Describe how ligand-gated and voltage-gated ion channels operate. (2p)
Biomed T4
Tema 3
Tentamen Neurovetenskap – VT01
2001-02-27
Post synaptic mechanisms (12 poäng)
Neurotransmitters exert their effects on cells by binding to and activating different types of
receptors. There are two major types of neurotransmitter receptors. Ligand gated ion channels
and G-protein coupled receptors.
a)
Could you explain how a typical ligand gated ion channel works?
3p
Ligand gated ion channels are neurotransmitter receptors with an intrinsic ion
channel. The ion channel is activated (opened) by the binding of the
neurotransmitter to specific extracellular domain(s) of the ligand gated ion channel.
Ligand gated ion channel such as the nicotinic acetylcholine receptor and glutamate
receptors are selective for positively charged ions and their activation results in cell
membrane depolarization. In contrast, ligand gated ion channels such as the
GABAA and glycine receptors are selective for negatively charged ions and their
activation results in cell membrane hyperpolarization or re-polarization.
b)
The binding of a neurotransmitter to a G-protein coupled receptor causes the activation of
the receptor, which in turn activates a G-protein. The activated G-protein consists of an
alpha subunit complexed with GTP and of a beta-gamma dimer. What reaction inactivates
the G-protein?
2p
The hydrolysis of GTP to GDP catalysed by the  subunit, which is a GTPase.
c)
What is the inactive form of the G-protein?
1p
The trimeric form of the G-protein (), complexed with GDP.
d)
A large number of G-proteins, once activated, regulate the activity of enzymes which
synthetize or degrade second messenger molecules. Could you give an example of a second
messenger (2) and name the enzyme which synthetizes it (2)? Second messengers often
regulate the activity of protein kinases. What reaction do protein kinases catalyze (2)?
cAMP, inositol 1,4,5-trisphosphate/diacylglycerol and cGMP;
adenylyl cyclase, phospholipase C and guanylyl cyclase (respectively);
Protein kinases catalyze the transfer of a phosphate group from ATP to specific
seryl, threonyl and tyrosil residues of proteins.
Tema 4
Synsinnet (8p) FACIT SAKNAS!
(If possible, please, formulate the answer in English).
Describe the different properties of the two main types (P and M) of retinal ganglion cells in
terms of:
a)
Their morphology
1p
b)
Projection patterns
1p
c)
Different receptive field properties
d)
Conduction velocity or axonal thickness
1p
1p
Describe the two main transcortical pathways originating in visual area 17 in terms of
e)
Which areas they involve
2p
f)
Their functional roles
2p
Biomed T4
Tema 5
Tentamen Neurovetenskap – VT01
2001-02-27
Smärta (4p)
Efter en traumatisk vävnadsskada iscensätts en rad processer som syftar till opitimal läkning, där
smärta kan sägas bidraga med att få organismen att vila och inte använda den skadade kroppsdelen.
a)
Många kan intyga att man i direkt anslutning till skadan kan uppleva dels en omedelbar
smärtsensation som inte är speciellt plågsam och en andra våg av smärta som kommer en
liten stund senare. Förklara det troliga neurofysiologiska underlaget till denna tudelade
smärtupplevelse.
2p
Information om skadan förmedlas dels via de snabbare tunna myeliniserade A-delta
fibrerna, dels via långsamma omyeliniserade C-fibrer. En teori är att den tudelade
smärtupplevelsen beror på att signalerna når CNS i två vågor via dessa två
fibertyper. En annan möjlighet är att den tudelade upplevelsen beror på att den
senare vågen beror på fördröjd aktivitet i sensitiserade sensoriska bansystem.
b)
Om skadan engagerar huden kan man efterhand uppleva smärta vid lätt stimulering dels
inom det område som blivit inflammerat (rött, varmt, svullet...), dels inom
omkringliggande större område som inte är inflammerat. Förklara mekanismer bakom
överkänsligheten dels inom det inflammerade området, dels utanför det inflammerade
området. Beskriv tydligt var någonstans längs de afferenta bansystemen som mekanismerna
äger rum.
2p
Överkänsligheten inom det inflammerade området beror primärt på en perifer
sensitisering, dvs en rad inflammatoriska substanser inom själva skadeområdet
såsom bradykinin, prostaglandiner, substance P, histamin, serotonin, NGF.. gör de
sensoriska afferenterna mer känsliga än vanligt.
Överkänsligheten i det kringliggande icke-inflammerade området beror på central
sensitisering som tros kunna äga rum i ryggmärgens dorsalhorn. Sensitisering av
postsynaptiska neuron via aktivering av olika glutamatkänsliga receptorer inkl
NMDA-receptorn, peptidreceptorer, kan här spela viktiga roller.
Tema 6
Sensorik – hörsel (8p)
FACIT SAKNAS!
Beskriv kortfattat örats anatomi och funktion (rita gärna):
a)
Genom vilken mekanism kan mellanörat försvaga överföringen av vibrationer till
innerörat?
2p
b)
Beskriv de två typerna av innerörats receptorceller och deras organisation, lokalisation och
innervation (gärna med figur).
3p
c)
Hur omvandlas vibrationerna i innerörat till nervimpulser? Var omvandlas lågfrekventa
vibrationer till nervimpulser?
3p
Biomed T4
Tema 7
Tentamen Neurovetenskap – VT01
2001-02-27
Locomotion (6p)
Describe basic nervous mechanisms involved in the control of locomotion. Characterize briefly:
a)
The motor pattern and the main phases of a step cycle. 1p
The step cycle consists of two phases - stance (the antigravity muscles, extensors, are
active) and swing (mainly flexors are active).
b)
Organization and location of locomotor limb controllers. 2p
The neuronal mechanisms generating locomotor pattern are located in the two
enlargements (cervical and lumbar) of the spinal cord. Each limb is controlled by a
separate spinal mechanism (limb controller) which provides basic features of a
movement - the rhythm, the duration of the flexor and extensor phases, and the level
of muscular activity. The limb controller contains a basic network (central pattern
generator, CPG) which is able to generate essential features of the motor pattern
even deprived of all sensory influences. The controllers of the four limbs interact to
produce coordinated locomotor movements of four limbs.
c)
How the limb controllers are activated. 1p
Spinal locomotor CPG is activated from mesencephalic or subthalamic locomotor
region through the reticulospinal pathway.
d)
Role of the sensory input from the limb receptors for the control of locomotion. 2p
The sensory input from the limb receptors is not necessary for generation of the
basic locomotor pattern. However, this input is important for adaptation of the
basic locomotor pattern to the environment (overstepping obstacles which were not
detected by visual system), for switching from the stance phase to the swing phase of
the cycle (the signals about unloading the limb).
Tema 8: Viljemässig motorik: Kontroll av handens finmotorik (8p)
Tänk Dig att Du skall utföra en inlärd, väl inövad, viljemässig rörelse: Du skall skriva Din
namnteckning. Du skall här redogöra för hur nervsystemet initierar denna rörelse, från det att Du
bestämt Dig för att utföra den.
a)
Beskriv kort hur CNS selekterar det rätta motorprogrammet för rörelsen. 4p
Basala ganglierna ansvarar för selektionen av rätt motorprogram (1p);
Aktivering av rätt motorprogram sker genom att basala gangliernas toniska
inhibition på Thalamus lyfts bort genom disinhibition (1p);
Rätt program kan väljas ut genom att den somatotopiska organisationen i
motorcortex bibehålles genom basala ganglierna (1p);
Motorcortex aktiverar Striatum, som då i sin tur hämmar Globus pallidus
interna/Substantia nigra pars reticulata. Detta leder till att hämningen därifrån ut
till Thalamus upphör, vilket ger möjlighet för Thalamus att aktivera rätt område i
motorcortex (1p);
(alt: Den direkta vägen genom basala ganglierna aktiveras, vilket utlöser rörelser
(1p)).
Biomed T4
b)
Tentamen Neurovetenskap – VT01
2001-02-27
Från vilket cortexområde kontrolleras handens finmotorik, och vilken är detta områdes
huvudsakliga funktion i den viljemässiga kontrollen av rörelser? 2p
Primära motorcortex (1p);
Utförande (initiering, aktivering) av rörelsen (1p).
c)
Vad är speciellt utmärkande för denna descenderande kontroll och vad är bakgrunden till
Din förmåga att med stor precision greppa pennan och styra den exakt när Du skriver Din
namnteckning? 2p
Direkt, monosynaptisk förbindelse till hand/fingermuskulaturens motorneuron
(1p);
detta ger en snabb, exakt kontroll av varje enskilt moment i rörelsen (1p);
Alt: snabb, precis sensorisk återkoppling viktig för att finjustera rörelsen (1p);
Alt: Cerebellum viktig för finjustering av rörelsen (1p).
Tema 9
Hypothalamus (8p)
Hjärnan reglerar en mängd kroppsfunktioner genom att kontrollera insöndringen av hormoner
från hypofysens framlob. Celler i hypothalamus som påverkar hypofysens sekretion ser till
utseendet ut som nervceller, men skiljer sig genom att de frisätter sina substanser till kärl.
a)
Vad kallas dessa celler? 1p
Neuroendokrina eller neurosekretoriska celler
b)
I vilken struktur finns de hypothalamiska cellernas nervändslut från vilka de
hypothalamiska faktorerna frisätts till kärlsystemet som går till hypofysens framlob? 1p
Eminentia mediana (median eminence).
c)
Nämn tre hypothalamiska faktorer (valfria), i vilka kärnor som de produceras och vilket
hypofyshormon som de reglerar. 3p
LHRH (GnRH) - mediala preoptiska arean - FSH/LH
Somatostatin - periventrikulära kärnan – GH
TRH - paraventrikulariskärnan (parvocellulär del) – TSH
CRH - paraventrikulariskärnan (parvocellulär del) – ACTH
Dopamin - arkuatuskärnan- prolaktin
GRH - arkuatuskärnan - GH
d)
Vilket hormon som huvudsakligen produceras i fettvävnaden påverkar födointaget och
därmed kroppsvikten via en interaktion med hypothalamus? 1p
Leptin
e)
Vad heter de två livsviktiga hormoner (nonapeptider; nio aminosyyror) som produceras i
hypothalamus och frisätts från hypofysens baklob (neurohypofysen) och vad har de för
funktion? (2 p)
Vasopressin - kärlkontraherande + ökar vattenresorption i njuren.
Oxytocin - kontraherar glatt muskulatur i livmodern + mjölkejektionsreflexen.
Biomed T4
Tentamen Neurovetenskap – VT01
2001-02-27
Tema 10 Cerebral cortex (6p)
Hjärnbarken kan inddelas på olika sätt. Som resultat fås ofta en såkallad karta (map).
a)
Ge 2 exempel på sådanna kartor (maps). 2p
Exempel på kartor är topologiskt ordnade representationer av den sensoriska
apparaten, typiskt somatotopiskt organiserade organisationer i den
somatosensoriska cortex; retinotopiskt organiserade i den primära syncortex och
angränsade delar ar syncortex. Också kartor som bygger på hjärnbarkens
mikrostruktur, t ex cytoarkitetonik eller histokemi är bra exempel. Till detta
kommer funktionella kartor. Exempel på dessa är kartor över regioner i vilka
neuronerna med preferens svarar på rörelse i synfältet eller kartor över regioner
från vilka man kan framkalla rörelser genom att stimulera cortex etc.
b)
Vad är kartlagt i de exempel du ger? 2p?
I t ex de somatotopiskt organiserade kartor är det neuronernas receptiva fält på
huden. Ju fler neuroner som har samma eller när överlappande receptiva fält på
huden, desto större är representationen av denna huddel i cortex (vilket många har
svarat ganska bra på). Cytoarkitektoniska kartor t ex beskriver den laminära
densiteten av neuroner och neuronernas morfologi. Kartan uttrycker alltså hur
många regioner av cortex det finns. Var för sig karaktäriseras regioner av en viss
laminär arkitektur och neuronmorfologi. I funktionella kartor representeras ofta en
indelning beroende på större neuronpopulationers preferens för olika stimulus
typer eller typer av motorisk rörelse eller rent av kognitiva funktioner (många har
förklarat väldigt bra vad kortorna betyder i de exempel de har valt, de flesta har
talat om somatotopiska kartor, retinotopiska kartor och tonotopiska kartor).
c)
Vad betyder gränserna mellan de olika områden i kartorna? 2p
Vad betyder gränserna mellan de olika områdena i en karta? Detta har varit ganska
svårt. I kapitel 8 i boken är beskrivet exempel på somatosensoriska kartor över area
3b och 1. Gränsen mellan 3b och 1 dras genom områden där det förekommer s k
omvändning (reversals) av representationen. Det vill säga är fingerspetsen på
pekfingret representerat i area 3b då stöter fingerspetsrepresentationen i area 1
exakt upp mot representationen i 3b. Går man längre in i område 1, eller 3b från
gränsen, då ändrar representationen sig till att omfatta mera proximala delar av
finger och hand. På samma sätt finns s k reversals eller omvändningar av
representationerna i gränserna mellan de retinotopiska områdena. Gränsen mellan
den primära visuella cortex och den sekundära visuella cortex (utgörs just precis av
den vertikala meridianen i synfältet). På båda sidor om denna gräns avlägsnar
representationerna sig systematiskt från den vertikala meridianen. Gränserna i
cytoarkitektoniska kartor är ofta dragna antingen efter subjektivt bedömande eller
när man kan se en klar ändring, både statistiskt och i mikroskopet i den laminära
arkitekturen. Gränserna i funktionella kartor är relativa och beror på när man
(ofta av statistiska skäl) bedömer att responspreferensen för stora populationer har
ändrat sig
Biomed T4
1. Glial cells
Tentamen Neurovetenskap – VT02
2002-02-26
6p
The brain is the most complex organism known to mankind. In the CNS there are approximately
1011 nerve cells and 10x more glial cells. There are micro glial and macro glial cells.
a)
Which important role do micro glial cells have? (1p)
Phagocytic macrophages.
Involved in the immonorespons in the brain.
b)
Name the three main groups of macro glial cells and describe an important function for
every one of them? (3p)
Astrocytes: Blood brain barrier
Oligodendrocytes: Myelinates central axons
Scwanncells: Myelinates peripheral axons
c)
What is Ranvier´s node and describe how the node can influence speed of
neurotransmission? (2p)
The unmyelinated space on an axon between the myelin sheets. This space is rich in
ion channels and is the site for propagation of the action potentials. The speed of the
action potential as is runs along the axon is increased as it jumps in a saltatory
action between the nodes.
2. Membrane potentials
6p
FACIT SAKNAS!
The resting potential and the action potential are two main functional properties of the nerve cell.
a)
What determines the resting potential? (2p)
b)
What is happening during the action potential? (3p)
c)
Give a definition of the term refractory period? (1p)
Biomed T4
Tentamen Neurovetenskap – VT02
2002-02-26
3. Synaptic transmission 6p
a)
At the postsynaptic level of chemical synapses different neurotransmitters can activate
ionotropic receptors (or ligand-gated ion channels) which can generate either excitatory or
inhibitory postsynaptic potentials (EPSPs or IPSPs). What characteristic of the ionotropic
receptor determines its ability to generate an EPSPs or an IPSPs (2)?
b)
Activation of a ionotropic receptor produces a postsynaptic response within about 1 msec.
In contrast, the response generated by a metabotropic receptor is considerably slower.
Which important class of proteins is directly activated by metabotropic receptors? (2)
c)
What other steps are necessary to activate a protein kinase and what important reaction
does the kinase catalyse? (2 p).
Answer: Ionotropic receptors can be divided into two groups: one which is
permeable to positively charged ions (mainly Na+ and K+) and whose activation
results in membrane depolarization (EPSPs) via increase in Na+ influx; the other
which is permeable to Cl- and whose activation results in hyperpolarization or
repolarization (IPSPs) via increase in Cl- influx.
Answer: Activation of a metabotropic receptor results in the activation of a Gprotein. The binding of the neurotransmitter to the receptor changes the
confromation of the G protein, followed by dissociation into an alpha-GTP and a
beta-gamma dimer. Both alpha-GTP and a beta-gamma dimer can regulate ion
channels or enzymes. Following activation of specific enzymes such as adenylyl
cyclase or phopholipase C second messenger molecules are generated which can in
turn activate protein kinases (e.g. cAMP-dependent proten kinase, protein kinase C,
etc.). The protein kinase in turn phosphorylates various substrates thereby
modulating their activity.
4. Synaptic vesicles 6p
Describe briefly the process that mediates fusion of a synaptic vesicle with the plasma
membrane. Please make a simple drawing (6p).
Answer: The fusion process depends on formation of a complex between so-called
SNARE proteins, synaptobrevin(=VAMP) in the vesicle membrane, and syntaxin
and SNAP-25 in the target membrane (i.e. at the active zone). The tight complex
formed between these proteins (i.e. the SNARE complex) is thought to press the two
membranes together which results in fusion. The whole process is triggered by entry
of calcium through voltage-gated calcium channels at the active zone. Calcium is
believed to act via the calcium-binding vesicle-protein synaptotagmin.
Biomed T4
Tentamen Neurovetenskap – VT02
2002-02-26
5. Sensory systems 6p
Sensory systems are all organized in a similar way. Different types of receptor cells transform
different forms of stimulus energy to electrical energy by a transduction mechanism that involves
ion channels. Information, encoded in nerve impulses, is transported by specific pathways, as a
rule involving thalamus, to specific areas in the brain.
a)
Name two touch receptor cells in the skin and describe the pathway in the spinal cord
where touch information is transported to the brain (the name and/or location in the spinal
cord). (2p)
Two of Pacini, Ruffini, Merkel and Meissner corpuscles. Ipsilateral dorsal column.
b)
Where is the primary auditory cortex (A1) located and which thalamic nucleus transmits
auditory information? (2p)
Temporal cortex and medial geniculate nucleus.
c)
Which second messenger and which type of ion channel are involved in the transduction
mechanism of olfactory receptor cells? (2p)
cAMP and cAMP gated (K) channels.
6. Development of cerebral cortex
a)
6p
Where are the neurons generated, which will form cerebral cortex? (2p)
In the ventricular zone (or in the proliferative zone around the ventricles
b)
How do the neurons move to their final destination in the cortex? (2p)
They move along processes of radial glia
c)
What is the growth cone? And what is its function? (2p)
A motile structure at the end of growing axons, involved in guiding axonal growth
Biomed T4
7. Reflexes
Tentamen Neurovetenskap – VT02
2002-02-26
6p
One class of movements is termed "reflexes". Please, describe different spinal reflexes and their
networks:
a)
The reflex that produces coordinated activity of the muscles around one joint (2p);
A coordinated activity of muscles around one joint is observed during stretch reflex.
A stretch of one muscle leads to contraction of this muscle and its agonists, and to
relaxation of its antagonists (a reciprocal coordination). Stretching the muscle
evokes activation of its 1a spindle afferents. These afferents enter the spinal cord
through the dorsal roots and monosynaptically excite motoneurons of their own
muscle and motoneurons of the agonistic muscles. Branches of the same 1a
afferents, through 1a inhibitory interneurons, inhibit motoneurons of the
antagonistic muscles.
b)
The reflex that evokes coordinated activity of muscles at different joints of the limb (2p);
Strong noxious stimuli evoke flexion of all joints in the ipsilateral limb (the flexion
reflex). The network underlying this coordination includes the cutaneous afferents
that excite flexor motoneurons of the ipsilateral limb through a polysynaptic path.
The same afferents, through a parallel chain of interneurons, evoke inhibition of the
extensor muscles.
c)
The reflex that evokes rhythmical movements of the limb (2p).
In animals, irritation of the skin causes a movement of the hind limb toward the
stimulated area followed by rhythmical, stereotype scratching movements aimed at
a removal of the irritant from the skin. Scratching motor pattern is generated by the
network (scratch CPG) located in the lumbosacral enlargement of the spinal cord.
Afferents from mechanoreceptors activated by the irritant enter the cervical and
thoracic regions of the spinal cord through the dorsal roots and excite
monosynaptically the propriospinal interneurons with long descending axons. These
neurons transmit commands that activate the scratch CPG, and it starts to generate
the scratching motor pattern.
Biomed T4
Tentamen Neurovetenskap – VT02
8. Voluntary movements in the lab
2002-02-26
6p
In order to merit yourself for your future career as a scientist in Biomedicine, you are working
during summer in a research lab, where you are doing calculations from experimental data. You
are using a calculator beside your work papers on the lab bench. Thus, on repeated occasions you
will have to move your eyes and your arm and hand to the calculator and press down a certain
combination of buttons.
You should now describe, briefly summarizing the key facts, the sequence of events that take
place in the different parts of the CNS that are involved in the following steps during this type of
voluntary movement:
a)
Planning of the movements
(2p)
Answer:
The region mainly responsible for motor planning is the (lateral) premotor cortex
(1p). This region is prepares for the movement by creating an adequate strategy for
the movement, and is also specifically involved in controlling arm movements to a
specific target.
b)
Programming of the sequence of finger movements at the calculator (1p)
Answer:
The main responsibility for the programming of movement sequences lies with the
medial premotor cortex (=supplementary motor area). In this area activity can be
detected also during “mental rehearsal” of the movement sequence, i.e. when
“performing” the movement mentally without actually executing it.
c)
Initiation and execution of the movements. (3p)
Answer:
To initiate the movements, the proper motor program(s) first have to be selected by
the Basal ganglia(1p); this occurs after selective activation, from the relevant
regions of the motor cortex, of the adequate groups of neurons in the striatum of the
Basal ganglia. The inhibitory output from the Basal ganglia is then removed from
the corresponding cells in the Thalamus, which will then become active
(disinhibition). This will lead to activation of the relevant regions of the primary
motor cortex (1p), and these descending signals will then activate the correct
interneurons and motoneurons in the spinal cord to execute the movement. The
descending control of the finger movements is executed monosynaptically on the
motoneurons.
Biomed T4
9. Pituitary
Tentamen Neurovetenskap – VT02
2002-02-26
6p
The brain controls the secretion of the anterior pituitary hormones via the release of
hypothalamic stimulating and inhibitory factors.
Posterior pituitary hormones are produced in
cell bodies that are located in the hypothalamus.
a)
Where are these hypophysiotropic hormones released and how do they reach the anterior
pituitary? (2p)
Neurosecretory nerve endings in the median eminence release their content into
portal vessels. The hypophysiotropic
hormones reach the anterior pituitary
cells via the blood.
b)
Which are the hormones secreted from the anterior pituitary? (2p)
GH, ACTH, TSH, prolactin, LH and FSH
c)
Which hypothalamic factor regulates which pituitary hormone? (2p)
GHRH - GH, somatostatin - GH, CRH - ACTH, TRH - TSH, dopamine - prolactin
and LHRH (GnRH) - FSH/LH
10. Learning and memory 6p
a)
How would you define learning and memory in a broad sense? (2p)
Learning is the process whereby information is acquired (1p); and memory is the
reflection of this learning process over time in terms of storage and
retrieval/recognition (1p).
b)
In what way is the hippocampus and the basal ganglia involved in memory functions? (3p)
The hippocampus establishes/formates new declarative memories and is hence
involved in short-term declarative memory (1.5p); Procedural learning and motor
skills when well learned will be stored (long term storage) in the basal ganglia among
other structures.
c)
How short is short-term memory? (1p)
Second-minutes or an example
Biomed T4
Neuroscience – Final Exam – VT03
2003-02-25
Theme 1 : Glial cells
Glial cells have several important functions in the nervous system.
Axons can be myelinated by glial cells in both the peripheral and in the central nervous system.
What is the name of the different myelinating glial cells and where in the nervous system can you
find them? (2p)
Give a principal difference of how myelination of axons occur in the central nervous system as
compared to in the peripheral nervous system. (2p)
Describe two important functions of astrocytes. (2p)
Theme 2 : The action potential
The nervous impulse rapidly transmits signals in the human body. Ion channels play key roles in
this impulse.
a. Describe an action potential. Which ion channels are involved, and in which states are the
channels in the different phases of the action potential? Describe the directions of the ion
flows. Convince me that you understand what is happening! (3p)
b.
How is the action potential propagated in a myelinated axon? (2p)
c) What is the approximate speed of the nervous impulse in an alpha-motor neuron? (1p)
Theme 3: Neurotransmitter release
The SNARE proteins play a central role in neurotransmitter release. Which are these proteins,
how do they act and how do we know that they are important ? (6p).
Theme 4: Glutamate receptors
Glutamate is the main excitatory neurotransmitter. Upon release of glutamate from the
presynaptic terminal, the concentration of neurotransmitter in the synaptic cleft is controlled by a
specific mechanism involving both neuronal and glial cells.
What is this mechanism? (1p).
What is the glutamate/glutamine cycle? (1p)
The neurotransmitter glutamate binds to and activates at least three types of ionotropic receptors:
AMPA receptors, kainate receptors and NMDA receptors. Describe what happens when
glutamate binds to an AMPA or kainate receptor. (2p)
NMDA receptors differ from the other two types of glutamate receptors in terms of ion
permeability. How? (1p)
Mg2+ plays an important role in the functioning of the NMDA receptor. Describe how Mg2+
interacts with the NMDA channel and what are the important consequences of such an
interaction (1p).
Biomed T4
Neuroscience – Final Exam – VT03
2003-02-25
Theme 5: Sensory systems
There are many types of receptor cells, transducing the stimulus energy into electric signals. At
least four different types of mechanoreceptors in the skin respond to touch. Mechanoreceptor
cells in the ear transduce sounds to electric signals. Mechanorecptor cells are also involved in the
sense of balance.
a.
There are two types of mechanoreceptor cells involved in hearing. Which? (1p)
b.
Where in the inner ear do we find them? (1p)
c.
Which are the two vestibular organs? (2p)
d.
Which is the main function of the two vestibular organs? (2p)
Theme 6: Visual system
Describe the different properties of the two main types (P and M) of retinal ganglion cells in
terms of:
1) their morphology (1p)
2) projection patterns (1p)
3) different receptive field properties (1p)
4) conduction velocity or axonal thickness (1p)
Describe the two main transcortical pathways originating in visual area 17 in terms of
5) Which areas do they involve ? (1p)
6) Their functional roles ? (1p)
Theme 7: Classification of movements
Characterize the different classes of movements (give examples), and role of the spinal cord,
brainstem and motor cortex in their generation (6p).
Theme 8: Cerebellum and motor control (6p)
Cerebellum has an important role in the control of movements. Describe briefly the following:
1. What aspects of motor control are regulated by the cerebellum? (1p)
2. Which are the two, principally different, kinds of information that are being processed in the
cerebellar cortex? (2p)
Give a brief description of the cellular interactions in the cerebellar cortex: the synaptic effects
between the main cell types, and the mechanism thought to underlie the regulatory function of
the cerebellar cortex in motor control. (3p)
Theme 9: Hypothalamus
The hypothalamus is involved in the regulation of homeostasis mainly via secretion of
neurohormones via the posterior pituitary into the systemic circulation or via secretion of
neurohormones into the pituitary portal blood vessels.
Name the two neurohormones which are released from the posterior pituitary lobe, in what
hypothalamic nuclei they are synthesized, what are their main functions in the body (6p)
Biomed T4
Neuroscience – Final Exam – VT03
2003-02-25
Theme 10: Cerebral cortex
We are interested in the general principles of the organization of the cerebral cortex (c.c.).
Describe the two main types of neurons in the c.c.(2p).
Give two main principles of connectivity between cortical areas (2p).
Give two examples of cortical maps, and explain where they appear and which functions they
might represent (2p).