Peer mentoring Flashcards
What are the limitations of block design?
- highly predictable occurrence of stimuli
- inflecible for more complex tasks
- ecological validity
- cant seperate trials by performance
What are advantages of event-related design?
- flexibility and randomisation
- post hoc sorting
- can look at novelty and priming
- can look at temporal dynamics of response
What does a BOLD signal measure?
the magnetic properties of oxygenated v. deoxygenated blood
What is a limitaion of the block design in MRI studies?
it is highly predictable
What are the 6 preprocessing steps?
- high pass filtering
- motion correction
- slice time correction
- coregistration
- normalisation
- spatial smoothing
Ultimately we want to do statistics on GROUP activation maps. Thus, we must get all of the brains into a ‘standard space’. How do we do this?
Complex algorithms to warp each subject’s brain into the shape of a TEMPLATE BRAIN
What was the original standard based on?
The brain of a 60-year-old French Woman
Why do we no longer use the original standard?
her brain may not be representative of all brains
What standard do we use now for comparing brains?
Montreal Neurological Institute (MNI) space
How was MNI created?
352 scans on normal controls, all right-handed
Advantages of whole brain analysis?
■ No prior hypothesis about areas involved needed.
■ Includes the whole brain.
Disadvantages of whole brain analysis?
■ Can lose spatial resolution –> due to inter-subject averaging.
■ Can produce meaningless lists of areas. Hard to interpret.
■ Depends highly on statistics and selected threshold.
■ Multiple comparisons problem.
Advantages of region of interest?
- hypothesis driven
- avoids multiple comparison problem
- simple
- generalisable
Disadvantages of region of interest?
■ Easy to miss things going on elsewhere in the brain.
■ Not always simple how to define ROIs.
Limitations of fMRI
- data is correlative
- temporal resolution is low
BOLD signal is arbitrary… meaning what?
it has no stbale baseline
How fast is the BOLD signal?
it is slow. peaks 4-5 seconds after stimulus onset and about 16 seconds to return to baseline
What are the two types of designs that can be used in an MRI scan?
block design (long periods of alternating task performance) and event-related design- trials of different conditions are randomly intermixed
How do we analyse results?
- multiple regression
- multiple regression per voxel
- contrast
- threshold of p<0.05
What are the three major sulci?
central, lateral and parietal-occipital
Where are basic physiological and metabolic processes controlled?
by groups of neurons in the brainstem, including thalamus and hypothalamus
What are the types of functions controlled in this area?
respiration, digestion,, glucose, metabolism, arousal…
What are some specific groups of neurons?
- reticular formation (control of arousal and sleep)
- suprachiasmatic nucleus (circadian rhythm)
- ventromedial nucleus (blood glucose into body fat)
What is the function of the cirpus callosum?
to allow messages to travel between hemispheres
where is body temperature controlled?
brain stem
Both perception and motor control have a _____ organisation
hierarchical
What is the correct order of inforamtion processing in perception?
primary visual/auditory/sensory motor areas -> second sensory areas -> association areas
How can we determine causality?
- neurosurgery
- stroke
- brain trauma
- neurodegeneration
- infection
What is neuropsychology
examines the effects of brain damage on cognitive abilities and behaviour
When did neuropsychology emerge?
Paul Broca in the 19th century
Who won the nobel prize for medicine in 1981?
Sperry and Gazzaniga
What surgery did Sperry and Gazzaniga’s patients have?
callosotomy
What is the WADA test
putting one hemisphere to sleep and seeing hwo it responds to stuff (e.g. holding a spoon)
What is hemispatial neglect?
the brain doesnt recognise an area of space
who studied temporal lobe amnesia?
brenda milner with HM
What are the key approaches in neuropsychology?
classic (localisation) and cogntiive (determine cognitive architecture)
What does cognitie neuropsychology rely on?
the logic of dissociation
what are the electrophysiological methods?
micro-electrode recordings and EEG
Eval of micro-electrode recordings
- The most direct and precise measure of brain activity
- However, because it is invasive, its use is very restricted both in terms of the subjects available and brain areas that can be investigated in patients
- High temporal resolution as it measures spikes and post-synaptic potentials
- High spatial resolution as it measures activity at the source
Eval of EEG
•Non-invasive
•High temporal resolution
> it measures fast electrical processes (post-synaptic potentials)
•Low spatial resolution
> the location of activity is difficult to infer
why is EEG not sensitive to spiking activity?
- the spatial extent of action potentials is too small and the time too short for them to be reflected in the EEG
- of the shape of the electrical fields they elicit
What is not an advantage of micro-electrode recordings?
A.Most direct and precise measure of brain activity
B.High temporal resolution
C.High spatial resolution
D.Being highly invasive
D) being highly invasive
Which is not a characteristic of EEG?
A.Being highly invasive
B.Non-invasive
C.High temporal resolution
D.Low spatial resolution
A) being highly invasive
WHat happens in the EEG frequencies as sleep becomes deeper?
Gradual slowing i.e. Lower frequencies
What is REM sleep?
Rapid Eye Movement sleep. EEG frequencies are very fast. During REM most vividly recalled dreams are believed to occur
What is higher frequency in the EEG associate with
Greater cortical activity
What area of the cortex is recordered to assess conscious awareness in patients in a vegetative state?
THe motor cortex
The first brain measurement technique to be used for this purpose was FMRI why might we use EEG instead?
EEG is cheaper and more portable - it can easily be deployed to the patient’s bedside
Which is not a diagnostic criteria for a vegetative state?
A. No overt motor responses to commands
B. No elaborate ‘voluntary’ or ‘willed’ behaviours from the upper or lower limbs
C. No evidence of visual orientation
D. No eye fixation greater than 5 seconds or tracking of visual OR auditory stimuli
E. Verbal Response
E) verbal response
What did Cruse et al find?
3/16 patients activated areas of the motor cortex according to the instructions
What discharges occur in patients suffering with epilepsy?
Abnormal/Excessive synchronisation of post-synaptic potentials, resulting in large amplitude discharges.
What is ictal activity?
during seizures
what is inter-ictal activity
between seizures
How are stimuli compared?
a. With ANOVA.
b. Qualitatively.
c. Separately averaged.
d. Just by looking.
C) separately averaged
What does SOA stand for?
stimulus onset asynchrony
what is the PRP paradigm
Psychological Refractory Period – Present 2 tasks in rapid succession. E.g. Tone discrimination or Word Relatedness.
What did Lien et al (2008) find?
Processing in Task 1 interferes with the processing of the target meaning in task 2. SO… it suggests that meaning is not accessed automatically.
What is SOA
the amount of time between stimulus 1 and stimulus 2
what is the inverse problem?
Inferring cortical generators from known scalp potentials. This is highly uncertain. There is an infinity of cortical current distributions that could result in one scalp distribution.
What are 3 EEG source estimation techniques
Epileptic EEG distribution on scalp
Localisation based on EEG source estimation
Localisation by correlation with concurrently acquired fmri data
WHich is not a strength of EEG:
a. High temporal resolution
b. It can provide detailed temporal information about processing a stimulus
c. Good spatial resolution
d. All of the above
c) good spatial resolution
which of these are not a weakness of EEG:
a. Limited spatial resolution
b. Cannot Localise activity with precision/confidence due to the complexity of the inverse problem
c. Good Temporal resolution
d. All of the above
c) good termporal resolution
Facts about micro-electrode recordings
- highly invasive: require surgery
- high temporal resolution: measure spikes and post-synaptic potentials
- high spatial resolution: measure activity at the source
facts about EEG
- non-invasive (innocuous)
- measures post-synaptic potentials
- high temporal resolution, sicne it measures fast electrical processes
- low spatial resolution location of activity; difficult to infer
Facts about PET
- moderatly invasive: radioactivity is introduced into the body
- measures indirect metabolic correlates of neural activity (e.g. blood, glucose)
- can measure synaptic transmission (e.g. labelling receptors)
- relatively high spatial resolution precision
- low temporal resolution because it measures slow processes
Facts about fMRI
- non0invasive (innocuous)
- measures indirect metabolic correlates of neural activity (e.g. blood)
- high spatial resolution (highest among all techniques)
- low temporal resolution, because it measures slow processes
How are neural signals transmitted?
- electric synapse: gap junctions connecting the cytoplasm of two neurons
- Chemical synapse: Signal transmission within a spiking neuron
What is the process of the electric synapse
A. Instantaneous current flow
> very fast transmission of electric signal across connexons, producing virtually no time delays
B. They are found where fast responses and/or synchronisation of activity is required.
> Fast action: Commanding escape responses (crayfish, fish)
> Synchronised activity: Inhibitory neurons in mammalian brain, eye-moving muscles
What is the process of the chemical synapse
A. Resting potential
> Membrane potential when the neuron is at rest (=no signal transmission)
B. Depolarisation
> Graded potential before reaching threshold (-55mV) when the neuron is excited (received signal)
C. Action potential
> Spikes are generated in the integration zone of a neuron if depolarisation reaches threshold (-55mV).
> Signal transmission inside neuron.
D. Signal transmission to next neuron
> It starts when action potentials reach in the output zone of a neuron.
What is a G protein-coupled receptr
It consist of three subunits, influencing adjacent ion channels.
When activated by a conformational change, G protein can interact directly with ion channels or control the release of another messenger molecule inside the postsynaptic cell.
1. Which are NOT typical ion channels? A. Voltage-gated channels B. Leak channels and ion pumps C. Ligand-gated channels D. Regular channels
D) regular channels
What are teo solutions to signal loss caused by increased distances
Long neurons with thicker axons - found in squids, and invertebrates.
Myelinisation of axons (Schwann cells) - mostly in vertebrates
What is neuroglia
Cells that assist the signal propagation (Schwann cells) and provide nutrients to neurons.
In what way are the Nodes of Ranvier involved in saltatory transmission
The neural membrane is exposed at the nodes of Ranvier for ion conductance through voltage-gated channels for Saltatory conduction.
What 2 things determine when a signal is picked up and by which signal is picked up?
- Type of neurotransmitter
2. Duration of neurotransmitter release
What is temporal summation
If the neurotransmitter is released for longer time into the synaptic cleft, then the postsynaptic potential is stronger.
What is spatial summation
If postsynaptic potentials, fired from two different neurons, arrive together in the integration zone, they are summed up.
What is EPSP
depolarisation
What is IPSP
hyperpolarisation
Examples of excitatory sunapses
glutamate, aspartate, nicotinic
examples of inhibitory synapses
GABA, glycine, muscarinic acetylcholine.
What is a spiking neuron
if the membrane at the integration zone is depolarised above a threshold, an action potential will be generated.
The more excitatory input arrives →
the stronger the output signal.
The more inhibitory input arrives →
the weaker the output signal/the neuron may not even fire.
What happens if 2 EPSPs are summed to reach the threshold
An action potential will be generated
What happens if 2 IPSPs are summed?
An action potential will not be generated, so the signal is not transmitted.
WHETHER A SIGNAL IS TRANSMITTED OR NOT DEPENDS ON…
HE SUM OF THE RELATIVE STRENGTHS OF EPSPs AND IPSPs THAT ARRIVE AT THE INTEGRATION ZONE TOGETHER WITHIN A GIVEN TIME WINDOW.
How is information coded in neural networks?
- spatial/temporal summation
- feedforward circuits
- feedback loop
What is spatial/temporal summation
determine the strength of the signal when it is passed on from one neuron to the next.
What is feedforward circuits
distribute the signal to many neurons through divergence of their connections, or is determined by collecting signals from many neurons through convergence.
What is feedback loops
(positive/negative) provide direct or indirect input influencing signals and thus information.
Is there a start/end in a neural network?
The observer defines the start and end.
Are networks hierarchical?
yes
Is one neuron a ‘queen’?
No, but there could be some small bosses or gatekeepers, as proposed by the grandmother cell/agnostic cell hypotheses.
Are networks clearly segregated from each other?
No, they can branch out into parallel streams, have feedback loops, share neurons with other networks, and change over time.
Which of these is an excitatory synapse?
a. Nicotinic acetylcholine
b. Muscarinic acetylcholine
c. Glycine
d. None of the above
a. nicotinic acetylcholine
Which of the following statements is false?
a. Neuroglia assist cell propagation
b. Myelination causes the problem of signal loss.
c. EPSPs/IPSPs arrive at the integration zone
d. Spiking neurons can generate action potentials.
b. Myelination causes the problem of signal loss.
What is non-declarative memory
Skill learning
Conditioning
Priming
What is declarative memory
Semantic memory (facts) Episodic (what, when, where)
What is Hebb synapse
The site of contact between neurons(synapse) plays a role in memory formation.
Hebbian theory claims that an increase in synaptic efficiency comes from a presynaptic repeated stimulation of the postsynaptic cell.
Hebb’s synapse in steps
- Cell A repeatedly excites cell b
- This causes a metabolic change
- A’s efficiency at firing B is increased
In what ways can the efficiency in synapses be increased
- Temporal Filtering: change in selectivity for the frequency range of spikes arriving in the axon terminal
- Gain Control: change in the amount of neurotransmitter released for a given signal
- Presynaptic facilitation or depression
What is presynaptic depression
This a form of synaptic plasticity studied in Aplysia.
The withdrawal reflex is mediated by sensory neurons that synapse to the motor neurons
After repeated stimulation over an hour, habituation occurs because the sensory neurons release less neurotransmitter to the motor neurons
If this process carries on over several days, there is a long term habituation caused by a retraction of some synaptic terminals from the sensory to motor neurons
Which sequence would cause associative learning in Pavlov’s Dog?
a. Food (US) preceding a sound (CS)
b. Sound (CS) preceding food (US)
c. Food (US) preceding salivation (UR)
b. Sound (CS) preceding food (US)
Are London taxi drivers hippocampi bigger or smaller than bus drivers
ANSWER: BIGGER
London taxi drivers hippocampi is larger than bus drivers.
- Greater grey matter volume in the mid-posterior hippocampi
- Less volume in anterior hippocampi
What three pathways in the hippocampus are involved with spatial memory formation
- Mossy fibre pathway (dentate gyrus to CA3 pyramidal cells).
- Perforant pathway
(input from entorhinal cortex) - Schaffer collateral pathway (CA3 to CA1 pyramidal cells)
CA1 pyramidal neurons (in the perforant pathway) have 2 glutamate receptors in their dendrites
QUESTION: What are these 2 receptors called?
- AMPA receptors
a. Ionotropc (ligand-gated ion chanels)
b. Open if glutamate binds to them → Na+ flow into postsynaptic neuron
c. EXCITATORY - Na+ influx depolarises EPSPs - NMDA receptors
a. Ligand and voltage gated
b. Cell resting = blocked by Mg2+
c. Binding glutamate is necessary but alone insufficient to open them
What 2 conditions are required to open NMDA receptors?
Binding of glutamate
Membrane depolarises above the threshold expelling the Mg2+ plug
Is hippocampal LTP the mechanism underlying spatial learning?
YES - Increasing evidence from various studies suggest this.
What’s the most economical way to inactivate the transmitter?
A: Re-uptake
B: Diffusion
C: Enzymatic degradation
D: Axonal propagation
A) re-uptake
Which phases of the synaptic sequence can drugs alter?
- Some act as early as the propagation of the action potential
- Others may influence the release of the transmitter
- Others modulate how the transmitter interacts with the post-synaptic channels (receptors)
- Finally, some alter the presence of the transmitter in the synapse by modulating its inactivation and recycling
Which chemical blocks sodium channels in the axon’s membrane? A: Dopamine B: Amphetamine C: Tetrodotoxin D: Tetanospasmin
C) tetrodotoxin
Describe two substances that influence the release of the transmitter
Tetanospasmin, which interferes with the vesicles of the neurotransmitter GABA fusing with the cell membrane.
This reduces the amount of GABA released into the synapse.
Botulinum toxin interferes with the release of Acetylcholine at nicotinic synapses, by preventing the vesicles from fusing with the cell membrane
Amphetamine facilitates the release of dopamine from the vesicles when these fuse with the membrane
Curare occupies acetylcholine’s receptors in inhibitory (nicotinic) synapses, blocking them and causing paralysis
A: TRUE
B: FALSE
B) False
interacts with excitatory synapses
What is an agonist
Imitates the behaviour of the neurotransmitter (NT)… INCREASING its effect.
example of an agonist
→ HEROIN; artificially modified form of morphine (opium).
→ It is an AGONIST of ENDORPHINS. Natural body chemicals that bind to OPIATE RECEPTORS and reduces pain and induces relaxation.
What are 2 Other Agonists and What Do They Bind To and What are they Involved in?
Marijuana (Cannabis) → Contains THC.
Agonist of Anandamide; Natural body chemical which binds to CANNABINOID RECEPTORS.
Involved in emotion, pain, appetite and memory.
Tobacco (Nicotine) → Stimulates NICOTINIC RECEPTORS. Agonist for ACETYLCHOLINE. (ACh)
Short-live generalised excitatory effect, e.g.. Increases blood adrenaline level.
•What are the 3 stages of neurotransmitter inactivation and recycling process….
1.Diffusion: Transmitter is lost in the inter-cellular space
2. Enzymatic Degradation: Enzymes break down the transmitter.
3. Re-Uptake (uptake): Transmitter is recycled either in pre or post-synaptic neuron.
This is the most economical way to inactivate the transmitter as it saves synthesis resources
Why is chocolate technically not “addictive”?
Because anandamide (agonist = THC) and phenylethylamine (related to amphetamine) are not found in amounts considered to have a substantial effect.
For the treatment of what disorder is the drug “Prozac” used and how does it work?
Prozac/Fluoxetine is used for the treatment of depression. It is an SSRI (Selective Serotonin Reuptake Inhibitor). It works by inhibiting the absorption of serotonin via the serotonin transporter without affecting other monoamines (e.g. dopamine).
Other treatment drugs for depression are MAO inhibitors and Tricyclic antidepressants.
What are benzodiazepines used to treat and how do they work?
GABA agonists used to treat anxiety disorders (characterised by deficits in GABA-ergic transmission).
They do not bind to the same receptor as GABA itself, therefore, are a non-competitive agonist.
Beta Blockers such as propranolol can also be used to treat anxiety disorders as they address the physiological symptoms such as increased heart rate.
SSRI’s are also commonly prescribed for anxiety.
What are neuroleptics used to treat and how do they work?
Neuroleptics such as Haldol are anti-psychotic drugs used to treat schizophrenia and other psychotic disorders (e.g. bipolar and major depressive disorder). They block the transmission of dopamine by binding to dopamine receptors without opening ion channels (they are antagonists).
Atypical Antipsychotics such as Quetiapine (seroquel) are also used.
What does cocaine do, what is the overall effect of amphetamines and what symptoms can this elicit?
Cocaine blocks the transporter of noradrenaline and dopamine, thus interfering with their re-uptake and boosting their effect. The overall effect is a boost in monoamine transmission (dopamine, noradrenaline, serotonin).
Increasing monoaminergic (especially dopaminergic) transmission can induce schizophrenia-like symptoms. Hence why you feel elation after ingesting the substance. It is important to note use of these drugs can elicit a psychotic ‘break’.
Antagonist = “You are antagonising me”
Inhibiting from doing something.
Agonist = “You are agonising me”
Stimulating a reaction.
Antagonist (Inhibits) – binds to post-synaptic receptors and…
blocks the binding of naturally occurring neurotransmitters.
Agonist (Stimulates/Imitates) – Binds to post-synaptic receptors and …
stimulates action potential.
What is the difference between a synaptic receptor agonist and antagonist? Illustrate your answer with a named receptor and its agonist and antagonist.
Antagonist (Inhibits) – binds to post-synaptic receptors and blocks the binding of naturally occurring neurotransmitters.
Agonist (Stimulates/Imitates) – Binds to post-synaptic receptors and stimulates action potential.
Example: GABA + Alcohol. In low doses alcohol acts as an agonist and in high doses acts as an antagonist. In very high doses alcohol destroys cell membranes and causes brain death.
Muller looked at the main reasons reported for drug use, can you name some?
- Improved Social interaction
- Facilitated sexual behaviour
- Improved cognitive performance and counteracting fatigue
- Facilitated recovery from and coping with psychological stress
- Self-medication for mental problems
- Sensory curiosity - Expanded perception horizon
- Euphoria, hedonia, and high
- Improved physical appearance and attractiveness
Effects of cocaine on the brain
Cocaine addiction is associated with brain damage risks, appearing minutes/hours after consumption
E.g. Seizures, early strokes, and lesions resulting in movement disorders
Along with reduced volume of the inferior portion of the frontal lobe
What is heroine associated with
A reduction in grey matter (e.g. in the frontal temporal regions
A reduction in white matter (spongiform leukoencephalopathy)
Brain hypoxia (reduced oxygen availability
Stroke (loss of blood supply)
Cerebral edema (water saturation)
Myelopathy (paralysis produced by spinal lesions)
What is alcohol linked to
Alcoholism is linked to Wernicke-Korsakoff syndrome
Wernicke’s encephalopathy -> brain shrinkage
- Characterised by changes in mental state and inability to concentrate, apathy.
- Korsakoff syndrome is characterised by anterograde amnesia, language problems and difficulty with movement.
- Korsakoff syndrome can sometimes be treated with thiamine supplements.
What did Yucel et al,2008 find
Cannabis use is associated with a reduction in brain volume, especially in the hippocampus and the amygdala
What did Moore et al, 2007 find
Longitudinal research shows that cannabis use is associated with development of psychotic symptoms
What are the causes of addiction
- Effects of drug-related cues - cue reactivity
- Effects of drug tolerance and withdrawal
- Drugs influences on processing of rewards and incentives (pleasure & motivation)
- Self medication
What is drug tolrance
reduced reaction to the same dose of a drug after repeated use.
what is drug withdrawal
symptoms which appear when stopping or reducing drug intake after having developed drug dependence, for example: sweating, fatigue, vomiting, insomnia, irritability and shaking.
What is tolerance a form of?
homeostatic protection, reducing the potentially harmful effects of the drug
•e.g. by raising heart rate in heroin addicts
but can lead to overdose
What is the Unviersal Reinforcement Circuit?
Involves activation of the VTA or Nucleus Accumbens (situated in the Basal Ganglia)
What did Wise et al (1978) find?
Administration of a dopamine antagonist (PIMOZIDE) increases lever pressing, even WITHOUT REINFORCEMENT…
What is the Incentive Salience Theory? How does it differ from the Anhedonia Hypotheses?
- Dopaminergic circuit involving NA (nucleus accumbens) and VTA (ventral tegmentum area) is responsible for the motivation to obtain a drug, not the pleasure obtained from it.
- Sensitisation to drugs occurs because addicts drug use strongly potentiates (increases the power of) the motivation-related dopaminergic synapses in the brain, with repeated use of the drug leading to greater responses in the dopamine circuit, independently from the effects of the drug on euphoria.
- Differs from Anhedonia hypotheses as…
- Anhedonia hypotheses relates to PLEASURE (reward).
- Incentive salience theory relates to MOTIVATION (incentive).
Comorbidity between drug dependence and mental illness does not clarify the direction of causality… why?
1.Drug use could cause mental illness through neurotoxicity.
•Substantial evidence that drug use causes mental illness (see earlier slide on cannabis and psychosis)
2.Mental illness could cause drug dependence through self-medication.
•E.g. McKee et al. (2011); Moeller et al. (2001).
3.Both causal mechanisms might exist and be reciprocal.
what is the spinal cord
The number and frequency of action potentials and the number of muscle fibers determine the force the muscle can generate.
what is the primary motor cortex
somatotopic organisation (aka map of the body), lesions lead to hemiplegia, loss of voluntary movement to contralesional side of body AKA if the left hemisphere is damaged, right side of body is affected)
what is the premotor cortex and SMA
planning and control of movement, lesions cause apraxia (inability to link simple gestures into meaningful actions)
what is the parietal and PFC
represents space, attention and sensorimotor integration, very complex functions. Lesions cause apraxia but also problems with attention, specifically spatial attention (aka neglect)
why are neurons in the spinal cord called Central Pattern Generators?
neurons are able to hold a representation of the entire pattern movements required to produce a complex motor act (refer to Brown and Sherrington, 1947)
Sheds light on hierarchical system
… If higher level neurons in the brain don’t represent specific action plans, what do they do?
REPRESENTATION OF MOVEMENT PLANS - do neurons encode:
a) Trajectory of movement (direction, distance, force)?
b) Location of target/end-point?
aNSWER: B
Evidence from Bizzi et al. (1984)
Severed somatosensory signals in monkeys, trained to reach target
Opposing force applied to arm (starting position)
Monkeys still able to reach for target as before (neurons in cortical motor regions represent movements by encoding the end-point location)
Neurons in the primary motor cortex show a preferred direction (i.e. they fire most strongly when movement is in that direction)
However, do neurons fire to a single direction or do they prefer a range of directions?
ANSWER: they prefer a range of directions
what is a vector
direction of cell’s preferred direction combined with info about strength of firing (hard to predict direction of movement)
what is a population vector
sum of individual neuron vectors (easier to predict direction of movement)
experiments related to visuomotor adaptation
- Actual movement trajectory VS Observed movement trajectory
- Effects of transcranial direct current stimulation (tDCS) on visuomotor adaptation: dissociation between cerebellum and M1 (primary motor cortex)
- Effect of transcranial magnetic stimulation of the cerebellum on forward models
what happens in visuomotor adaptation
The hands of the subjects were hidden and mismatch, between where they moved their hand and where they saw it moving, was created. They later adapted their movements to this mismatch. Increased activation was also shown across many different motor regions during the adaptation phase.
Patients with lesions in areas involved in motor control, including cerebellum, prefrontal cortex and parietal cortex have deficits in learning to move in novel environments. This suggests that motor regions are critical.
In tDCS, electrical currents are applied to the scalp, producing changes in the…
excitability of neurons under the electrode.
tDCS of the cerebellum led to a …
faster rate of adapation
tDCS of the motor cortex led to….
increased retention of adaptation (more error for a longer period of time after the end of adaptation).
Effect of transcranial magnetic stimulation of the cerebellum on forward models
Subjects moved their arm to the right. When a tone occurred, they made a movement to a visual target. A prediction of where your hand would be in the future was required, because there was a delay, between hearing the tone and actually initiating the forward movement. If the subject just generated a motor command when they heard the tone, they would miss the target since the motor command trajectory would be out of date and inaccurate by the time the motor command was actually initiated.
The subjects were pretty accurate in the experiment. Average directional errors in the TMS condition were consistent with reaching movements being planned and initiated from an estimated hand position that was 138 ms out of date. The results show that the forward models generated by cerebellum uses information about future position of limb to compute the trajectory required to hit the target.
What is the role of the Basal Ganglia in Motor Control?
- Basal ganglia play a key role in movement initiation
- Pathways are mutually antagonistic:
- Direct pathway leads to increased excitation (Movement initiation)
- Indirect pathway leads to increased inhibition (Movement inhibition)
This enables the system to achieve a balance:
- Activation of the direct pathway can lead to too much movement, which can be balanced out by inhibitory activation of the indirect pathway.
What is the cause of Parkinsons disease
Loss of dopamine neurons in the basal ganglia
what are the symptoms of parkinsons disease
Reduction in voluntary movement (Hypokinesia)
Slow movement (Bradykinesia)
Tremor
What are the treatments of parkinsons disease
- Levodopa (‘L-dopa’) is a dopamine precursor, which crosses the blood-brain barrier and enters the CNS, converting into dopamine
- Deep Brain Stimulation (DBS)
Cognitive function of basal ganglia experiment
- Subjects are trained to press left for red things and squares and right for green things and triangles. Then in the test phase they see pairs of stimuli and have to press left or right – told to respond to either the colour or the shape. On some trials, they respond to the same dimension and on others it switches.
- Patients with Parkinson’s Disease were particularly impaired on switching trials. Basal ganglia appears to play a dual role in action and cognition, allowing new thoughts and new movements to occur. This highlights the strong links between the cognitive and motor systems.
- What role(s) do cerebellum and M1 (primary motor cortex) play in visuomotor adaptation?
a) They have the same role.
b) They have negative roles.
c) Cerebellum is involved in learning new mapping by generating forward models while M1 is important for consolidating newly learnt mapping.
d) Cerebellum is involved in consolidating newly learnt mapping while M1 is important for learning new mapping by generating forward models.
c) Cerebellum is involved in learning new mapping by generating forward models while M1 is important for consolidating newly learnt mapping.
- What role(s) does basal ganglia NOT play in motor control?
a) It has no role.
b) Movement initiation.
c) Movement inhibition.
d) Balance between mutually antagonistic pathways .
a) It has no role.
What are the types of sensroy systems
Mechanical e.g. touch, pain Visual Thermal (decreases and increases in skin temperature) Chemical e.g. smell and taste Electrical
what are sense organs
structures that contain receptors and interneurons that are specialised for detecting and processing certain types of stimuli
What is the function of receptor neurons?
- specialized to detect internal and external stimuli of a sensory modality and to act as a filter for stimulus information.
- They transform stimulus energy into neural signals, which are transmitted to the sensory interneurons
what is the problem with receptor neurons?
If all neurons share the same vocabulary of neural signals, how does the brain know which receptor responded to a stimulus so modality can be determined?
What does CNS interpretation depend on?
which axons convey the signals (principle of sensory labelled lines).
Why does each type of touch receptor have a distinct pathway to the brain?
Different qualities of skin stimulation can be communicated to distinct areas in the brain
What is a receptive field?
The region in space in which stimuli affect that neurons firing rate
Example of small receptive field?
Merkel’s disc and Meissner’s corpuscle
They are sensitive to stimuli in small areas of the skin
Example of wide receptive field
Example: Pacinian corpuscles and Ruffini’s endings
In deeper layers, sensitive over a larger area of skin
what is a tonic receptor
slow loss of response
what is a phasic receptor
fast loss of response
where is the primary somatosensory cortex located
in the postcentral gyrus in the parietal lobe of the human brain. Brodman areas 1,2 and 3a,b
How can sensory input be suppressed?
- often suppression involves accessory organs. SUch structures reduce the intensity or alter the stimulus before it reaches the receptor (e.g. eyelids, muscles)
- or it can be via top-down processes. e.g. brain stem sends messges to receptor cells in the eat to selectively dampen sounds
what is a tonic receptor?
a. A brain region
b. A receptor with a fast loss of response
c. A type of stimulus
d. A receptor with a slow loss of response
d. A receptor with a slow loss of response
Which receptor will respond if A is less sensitive than B? Hint: there are two correct answers
a. None, because they have conflicting thresholds
b. Both, because the stimulus is in both receptive fields
c. Both, if stimulus intensity is high
d. B, if stimulus intensity is low
c. Both, if stimulus intensity is high
d. B, if stimulus intensity is low
How do we detect and interpret patterns of electromagnetic radiation?
Differences in wavelenth and intensity
How did vertebrate eyes evolve?
Eyes evolved through a sequence of improvements for detecting directions and forming an image
Advanced types of eyes have evolved several times in the animal kingdom
Fossils dating back to the Cambrian explosion
Daster movement and navigation in animals required better vision
What does SCN stand for?
a) Saskatchewan Communications Network
b) Suprachiasmatic Nucleas
c) Symmetrical Condensed Node
d) Stem Cell Network
b) Suprachiasmatic Nucleas
What does the SCN regulate?
a. Visio-spatial recognition
b. Colour perception
c. Circadian rhythms
d. None of the above
c. Circadian rhythms
Where is the Pineal gland and what does it do?
Unpaired midline structure near the epithalamus
Produces melatonin during darkness
What is the fovea?
A → The central portion of the retina. This is where the highest density of photoreceptors are… SO, it is the center of our gaze.
How many times do saccades occur per second?
2-3 times
What did Land, Mennie and Rusted., (1999) do and find?
→ Used a head mounted eye movement video camera.
→ A white dot indicated foveal direction. A second camera recorded what the person did.
→ Foveal direction was always close to the object being manipulated, very few fixations were irrelevant to the task.
→ Roughly 1/3rd of fixations on objects were; locating objects for later use, directing the hand to a new location, guiding e.g., kettle and lid, and checking variable state e.g., water level.
SO… although tea-making is automated, the eyes closely monitor every step of the way. This is unconscious attention.
Do we notice eye movements when awake?
yes and no
There are 4 different types of eye movements what are they?
Smooth pursiut movements, saccades, optokynetic nystagmus, vestibulo-occular movements.
What are saccades
Rapid eye movements to a new position between fixations. Why? To scan the scene.
what are smooth pursuit movements
Slow, keeps a moving stimulus on the fovea.
what are occular movements
Brings the eye back from peripheral (side) to a central position after following a large-scale moving stimulus (whilst head is still).
what are vestibulo-occular movements.
Compensate for head movement, done by moving the eye the same distance but in the opposite direction. Why? Maintain a constant field of view
where does automatic control come from?
superior colliculus
where does conscious control come from
cortical frontal eye fields
The human eyes contain how many receptor cells?
95 million
what are rods
Specialised for high sensitivity to see in DIM light.
what are cones
Specialised for high acuity and high speed of response to see in BRIGHT light
What type of visual receptors aid seeing during the night?
rods
Dim light vision uses the central fovea. True or False?
false
Sharpness of vision is highest in the fovea, and decreases towards the periphery.
At night, sharpness is sacrificed for sensitivity so it is more advantageous to have no rods in the fovea.
What is the name of the light sensitive protein in the membrane of photoreceptors?
opsin
How many functional classes of rods are there?
What is the name of this opsin?
A: 1
A: Rhodopsin (RH1)
Conformational change in rhodopsin activates a G protein called what?
Transducin
Transducin causes Na channels to close. true or false
true
when membrane (Na) becomes closed, does it become more polarised
The membrane becomes MORE polarised.
Do receptors cells have graded or spiking responses?
graded
Retinal ganglion cells send action potentials to the brain
What are the names of the two main visual pathways?
A: Geniculate-striate pathway and the Extrageniculate pathway
Which is the Geniculate -striate pathway?
Retina - V1 - LGN - higher visual cortex
Retina - LGN - V1 - higher visual cortex
Retina - V1 - higher visual cortex
Retina - LGN - higher visual cortex
Retina - LGN - V1 - higher visual cortex
What is NOT the differences between retinal image and perceived image?
a. 2D VS 3D
b. Inverted VS Upright
c. Black and white VS . Colourful
d. Meaningless VS Meaningful
d. Meaningless VS Meaningful
What does Machband effect find?
a. In the Machband pattern, each bar appears lighter on its left edge and darker on its right edge. However, they are uniform in their physical brightness (reflectance)
b. Lateral inhibition occurs where the neurons are interconnected. As they tend to inhibit their neighbours, the photoreceptors report receiving less light than they actually do on the right edge (i.e. that edge looks darker to us)
c. Nothing
d. Uncertain
b. Lateral inhibition occurs where the neurons are interconnected. As they tend to inhibit their neighbours, the photoreceptors report receiving less light than they actually do on the right edge (i.e. that edge looks darker to us)
QUESTION: What are the 2 cells involved in horizontal connections?
a. Horizontal and ganglion cells
b. Amacrine and bipolar cells
c. Horizontal and amacrine cells
d. None of the above
C) Horizontal and amacrine cells
QUESTION? What are the 2 types of vertical connections?
Fovea = 1 cone to 1 bipolar cell Periphery = many cones to 1 bipolar cell, many bipolar cells to 1 ganglion cell
QUESTION: what type of receptive field (RF) do bipolar cells have?
Excitatory-inhibitory RF
Vertical-horizontal RF
Center-surround RF
Center-surround RF
What are the 2 types of center-surround receptive fields?
ON-center and OFF-centre
QUESTION: What neurotransmitter is involved in ON- and OFF-center bipolar cells?
a. Dopamine
b. Adrenaline
c. Glutamate
c. glutamate
QUESTION: what do ON- and OFF-centre bipolar cell RFs respond to?
a. Movement of light spots
b. Electrical activity
c. Hormones
Movement of light spots
what happens when you shine a light on the center of an ON-center ganglion cell?
a. It depolarises
b. Rate the cell fires action potentials (spikes) increases
B) Rate the cell fires action potentials (spikes) increases
when does a bipolar cell depolarise
when light spot on center increases
when does a ganglion cell increase firing rate
when light spot on center increases
If the whole receptive field is stimulated… how would the ganglion cell response?
a. Fire at the highest rate
b. Fire at the lowest rate
c. Fires at spontaneous rate (at rest)
Fires at spontaneous rate (at rest)
What did Hubel & Wiesel (1977) propose in their ice-cube model of the V1?
All neurons in an orientation column share the same preference for a particular orientation of a bar stimulus in their receptive field
Retinotopic organisation: Signals from co-located ganglion cells in the retina are processed by respectively co-located cortical neurons within each orientation column
Hubel and Wiesel (Harvard, USA) were awarded the Nobel prize in 1981 for their work in the 60s and 70s
What did Hubel and Wiesel propose?
Hubel and Wiesel proposed that simple cells in the orientation columns receive input from several neighbouring retinal ganglion cells.
What is Marr’s (1982) theory of visual processing in the brain?
From retinal image to 3D model in the cortex
What does spatial frequency of a visual stimulus mean?
The number of light/dark (or color) cycles that the stimulus shows per degree of visual space.
What is the difference in response to bar orientation between simple and complex cortical cells?
Simple cortical cells (aka bar detectors or edge detectors): respond best to an edge or a bar of particular width, orientation, and location in the visual field.
Complex cortical cells: respond best to a bad or particular size and orientation anywhere within a particular area of the visual field.
What is/are the function(s) of simple and complex cells?
a. Analysis of contours and boundaries analysis of objects
b. Shape and positional invariance
c. Contour enhancement for object identification
d. All of the above
e. None of the above
a. Analysis of contours and boundaries analysis of objects
b. Shape and positional invariance
c. Contour enhancement for object identification
d. All of the above
What is perceptual shape constancy?
We recognise the same shape from different viewpoints and directions despite the distortions in the retinal projections.
What is size constancy?
When objects are at different distances, the size of their retinal projection varies.
Context information allows the brain to judge whether the same object is seen from a different distance or a different object is seen.
What are the main visual streams in the cortex of the primate/human brain?
Dorsal stream - where system, interacting with the world.
Ventral stream - what system, making sense of the world.
what is the dorsal stream
where system, interacting with the world.
what is the ventral stream
what system, making sense of the world.
What is the ventral visual stream for?
Interacting with the world
Making sense of the world
All of the above
None of the above
Making sense of the world
How do we detect and interpret patterns of electromagnetic radiation?
Differences in wavelenth and intensity
How did vertebrate eyes evolve?
Eyes evolved through a sequence of improvements for detecting directions and forming an image
Advanced types of eyes have evolved several times in the animal kingdom
Fossils dating back to the Cambrian explosion
Daster movement and navigation in animals required better vision
What does SCN stand for?
a) Saskatchewan Communications Network
b) Suprachiasmatic Nucleas
c) Symmetrical Condensed Node
d) Stem Cell Network
b) Suprachiasmatic Nucleas
What does the SCN regulate?
a. Visio-spatial recognition
b. Colour perception
c. Circadian rhythms
d. None of the above
c. Circadian rhythms
Where is the Pineal gland and what does it do?
Unpaired midline structure near the epithalamus
Produces melatonin during darkness
What is the fovea?
A → The central portion of the retina. This is where the highest density of photoreceptors are… SO, it is the center of our gaze.
How many times do saccades occur per second?
2-3 times
What did Land, Mennie and Rusted., (1999) do and find?
→ Used a head mounted eye movement video camera.
→ A white dot indicated foveal direction. A second camera recorded what the person did.
→ Foveal direction was always close to the object being manipulated, very few fixations were irrelevant to the task.
→ Roughly 1/3rd of fixations on objects were; locating objects for later use, directing the hand to a new location, guiding e.g., kettle and lid, and checking variable state e.g., water level.
SO… although tea-making is automated, the eyes closely monitor every step of the way. This is unconscious attention.
Do we notice eye movements when awake?
yes and no
There are 4 different types of eye movements what are they?
Smooth pursiut movements, saccades, optokynetic nystagmus, vestibulo-occular movements.
What are saccades
Rapid eye movements to a new position between fixations. Why? To scan the scene.
what are smooth pursuit movements
Slow, keeps a moving stimulus on the fovea.
what are occular movements
Brings the eye back from peripheral (side) to a central position after following a large-scale moving stimulus (whilst head is still).
what are vestibulo-occular movements.
Compensate for head movement, done by moving the eye the same distance but in the opposite direction. Why? Maintain a constant field of view
where does automatic control come from?
superior colliculus
where does conscious control come from
cortical frontal eye fields
The human eyes contain how many receptor cells?
95 million
what are rods
Specialised for high sensitivity to see in DIM light.
what are cones
Specialised for high acuity and high speed of response to see in BRIGHT light
What type of visual receptors aid seeing during the night?
rods
Dim light vision uses the central fovea. True or False?
false
Sharpness of vision is highest in the fovea, and decreases towards the periphery.
At night, sharpness is sacrificed for sensitivity so it is more advantageous to have no rods in the fovea.
What is the name of the light sensitive protein in the membrane of photoreceptors?
opsin
How many functional classes of rods are there?
What is the name of this opsin?
A: 1
A: Rhodopsin (RH1)
Conformational change in rhodopsin activates a G protein called what?
Transducin
Transducin causes Na channels to close. true or false
true
when membrane (Na) becomes closed, does it become more polarised
The membrane becomes MORE polarised.
Do receptors cells have graded or spiking responses?
graded
Retinal ganglion cells send action potentials to the brain
What are the names of the two main visual pathways?
A: Geniculate-striate pathway and the Extrageniculate pathway
Which is the Geniculate -striate pathway?
Retina - V1 - LGN - higher visual cortex
Retina - LGN - V1 - higher visual cortex
Retina - V1 - higher visual cortex
Retina - LGN - higher visual cortex
Retina - LGN - V1 - higher visual cortex
What is NOT the differences between retinal image and perceived image?
a. 2D VS 3D
b. Inverted VS Upright
c. Black and white VS . Colourful
d. Meaningless VS Meaningful
d. Meaningless VS Meaningful
What does Machband effect find?
a. In the Machband pattern, each bar appears lighter on its left edge and darker on its right edge. However, they are uniform in their physical brightness (reflectance)
b. Lateral inhibition occurs where the neurons are interconnected. As they tend to inhibit their neighbours, the photoreceptors report receiving less light than they actually do on the right edge (i.e. that edge looks darker to us)
c. Nothing
d. Uncertain
b. Lateral inhibition occurs where the neurons are interconnected. As they tend to inhibit their neighbours, the photoreceptors report receiving less light than they actually do on the right edge (i.e. that edge looks darker to us)
QUESTION: What are the 2 cells involved in horizontal connections?
a. Horizontal and ganglion cells
b. Amacrine and bipolar cells
c. Horizontal and amacrine cells
d. None of the above
C) Horizontal and amacrine cells
QUESTION? What are the 2 types of vertical connections?
Fovea = 1 cone to 1 bipolar cell Periphery = many cones to 1 bipolar cell, many bipolar cells to 1 ganglion cell
QUESTION: what type of receptive field (RF) do bipolar cells have?
Excitatory-inhibitory RF
Vertical-horizontal RF
Center-surround RF
Center-surround RF
What are the 2 types of center-surround receptive fields?
ON-center and OFF-centre
QUESTION: What neurotransmitter is involved in ON- and OFF-center bipolar cells?
a. Dopamine
b. Adrenaline
c. Glutamate
c. glutamate
QUESTION: what do ON- and OFF-centre bipolar cell RFs respond to?
a. Movement of light spots
b. Electrical activity
c. Hormones
Movement of light spots
what happens when you shine a light on the center of an ON-center ganglion cell?
a. It depolarises
b. Rate the cell fires action potentials (spikes) increases
B) Rate the cell fires action potentials (spikes) increases
when does a bipolar cell depolarise
when light spot on center increases
when does a ganglion cell increase firing rate
when light spot on center increases
If the whole receptive field is stimulated… how would the ganglion cell response?
a. Fire at the highest rate
b. Fire at the lowest rate
c. Fires at spontaneous rate (at rest)
Fires at spontaneous rate (at rest)
What did Hubel & Wiesel (1977) propose in their ice-cube model of the V1?
All neurons in an orientation column share the same preference for a particular orientation of a bar stimulus in their receptive field
Retinotopic organisation: Signals from co-located ganglion cells in the retina are processed by respectively co-located cortical neurons within each orientation column
Hubel and Wiesel (Harvard, USA) were awarded the Nobel prize in 1981 for their work in the 60s and 70s
What did Hubel and Wiesel propose?
Hubel and Wiesel proposed that simple cells in the orientation columns receive input from several neighbouring retinal ganglion cells.
What is Marr’s (1982) theory of visual processing in the brain?
From retinal image to 3D model in the cortex
What does spatial frequency of a visual stimulus mean?
The number of light/dark (or color) cycles that the stimulus shows per degree of visual space.
What is the difference in response to bar orientation between simple and complex cortical cells?
Simple cortical cells (aka bar detectors or edge detectors): respond best to an edge or a bar of particular width, orientation, and location in the visual field.
Complex cortical cells: respond best to a bad or particular size and orientation anywhere within a particular area of the visual field.
What is/are the function(s) of simple and complex cells?
a. Analysis of contours and boundaries analysis of objects
b. Shape and positional invariance
c. Contour enhancement for object identification
d. All of the above
e. None of the above
a. Analysis of contours and boundaries analysis of objects
b. Shape and positional invariance
c. Contour enhancement for object identification
d. All of the above
What is perceptual shape constancy?
We recognise the same shape from different viewpoints and directions despite the distortions in the retinal projections.
What is size constancy?
When objects are at different distances, the size of their retinal projection varies.
Context information allows the brain to judge whether the same object is seen from a different distance or a different object is seen.
What are the main visual streams in the cortex of the primate/human brain?
Dorsal stream - where system, interacting with the world.
Ventral stream - what system, making sense of the world.
what is the dorsal stream
where system, interacting with the world.
what is the ventral stream
what system, making sense of the world.
What is the ventral visual stream for?
Interacting with the world
Making sense of the world
All of the above
None of the above
Making sense of the world
Which pathway is for colour and which is for motion (P or M)
P- colour
M- motion
What happens to unabsorbed light
It is reflected
What happens to the reflected light
It gets absorbed by eye media and water
What instrument is used to measure spectral reflectance
Photospectrometer
How does the absorption of light by the ocular media change with age?
Lens of the human eye absorbs UV and with increasing age also short wavelengths (violet, blue)
W hat are the three types of colour vision?
Dichromacy, trichromacy, tetrachromacy
What causes colour defects?
X-chromosome recombination
●S-cone opsin gene on chromosome 7
●M- and L-cone opsin genes on X chromosome
What is the difference between severe and mild colour deficiency?
Severe colour-deficiency: (only two cone opsins expressed in retina), lacking cones
●Mild colour-deficiency: (one cone opsin is anomalous), mutated form of pigment – small shifts in the spectrum
Wh at is the theory for the development of colour vision in primates?
Trichromatic vision is a result of gene duplication in primates (therefore close overlap of L- and M-cone spectral sensitivities), it is optimal to detect and distinguish ripe fruit
What are the issues with this theory? (Vision in primates)
A lack of support.
B.Observations in natural habitats do not reveal yet any differences in behavioural profiles
How are cone receptor signals processed? A.They are subtracted B.They are added C.They are multiplied D.A and B
A&B
What do ganglion cells in the LGN fire in response to and what are they inhibited by?
The type of wavelength determines how the LGN ganglion cells respond, to some wavelengths they fire, and to others they are inhibited.
Name the chromatic pathways
S/(L+M) (old, mammalian)
B.L/M (new, trichromatic primates)
Name the achromatic party
L&M
What did Young-Helmholtz theory tell us about colour?
Humans have trichromatic colour vision
What does additive colour mixing tell us about human colour perception?
With additive colour mixing we can create any colour visible to humans by mixing the three wavelengths corresponding to the peak sensitivities of the three types of cone receptors
How would you perceive a successive colour contrast effect?
Looking at an original colour contrast would cause you to perceive a contrast later which is not there
colour would you perceive if you had an equal mixture of green, red, and blue
White
What is colour constancy?
Colour constancy is the ability to recognise colours under different illuminations.
QUESTION: all sound waves hit a single location, this is the…
Tympanum
Vibrations travel from the tympanum to the middle ear where they are amplified
how are hair cells arranged in the cochlea?
ANSWER: they are arranged tonotopically along the basilar membrane.
High frequencies displace the basilar membrane at the base
Low frequencies displace the basilar membrane at the apex
QUESTION: What are the two types of auditory receptors?
: inner and outer hair cells… these are non-spiking receptor cells and respond to mechanical stimulation (aka stretch ion channels) with depolarisation
what is the function of stereocilia?
Opens in channels
How many synapses and nerve fibres does the organ of Corti have?
B) 4
2 are afferent (hair cells → bran)
2 are efferent (brain → hair cells)
what synaptic neurotransmitters are involved with activity at the various hair cell synapses?
glutamate, acetylcholine, GABA and dopamine
Which area of the brainstem receives input from both cochlear nuclei?
C) Superior olivary nucleus (bilateral input, 1st stage in CNS at which binaural effects are processed)
How are sound source location computed?
calculating differences in delay and intensity between two ears
-Input reaches each ear at different times → determines how sound is perceived
-Jeffress model - brain codes latency (time) difference between sound heard by left and right ears by coincidence detection
Which of these chemical forms of communication refers to hormones? A.Neurocrine B.Endocrine C.Pheromone D.Allomone
Endocrine communication is where chemicals are released into the bloodstream where the selectively affect distant organs
What are hormones?
Bioregulators of the endocrine system
What are the three main types of hormones
Protein (including peptides) , amine and steroid
What are some examples of protein hormones?
Oxytocin,Vasopressin, prolactin, Insulin, glucagon, GH, thyroid-stimulating hormones, follicle-stimulating hormones, luteinizing hormones
●Releasing hormones e.g. CRH and GnRH
Peptide hormones have a short chain. True or false?
True
What are some examples of amine hormones?
Epinephrine, norepinephrine, melatonin and thyroid hormones
Monoamine hormones are smaller and more complex than protein hormones. True or false?
They are smaller. They are simpler NOT more complex
Protein and amine hormones - They act slowly. True or false?
False. They act rapidly (secs to mins)
How can sensitivity be altered?
A.Increasing (upregulating) or decreasing (downregulating) the number of receptors on cells
Which one of these is NOT the characteristic of steroid hormones?
a. Derived from cholesterol
b. Made from four interconnected carbon rings
c. Act on specific receptors in cells
d. Act ‘rapidly’ (secs to mins)
D
Examples of steroid hormones do NOT include … ?
a. Oestrogen
b. Progestins
c. Glucocorticoids
d. Growth hormone (GH)
D
What is an example of brain regulation?
The alarm response
What is an example of brain and pituitary regulation?
Temperature regulation
Which of these is NOT a target of a pituitary hormone?
A.Testes B.Breast C.Kidney D.Bone and Soft Tissues E.Uterus
NONE OF THEM. They are all involved… Look out for this kind of question as your exam can have typos…human error applies to lecturers too
QUESTION: What is the main structure and hormone involved with biological rhythms? A)Pituitary gland and melatonin B)SCN and melatonin C)Hypothalamus and ghrelin D)None of the above
ANSWER: D) None of the above
→ STRUCTURE: Pineal gland (PG)
→ HORMONE: Melatonin (amine hormone)
QUESTION: what is an example of this? (hint: they are cute and small)… and what happens during spring time?
ANSWER: Hamsters
1.Sense shorter nights
2.PG reduces nocturnal secretion of melatonin
3.Hypothalamus less sensitive to -ve feedback effects of gonadal steroids
4.More GnRH released
5.More gonadotropin released, gonads swell, READY TO BREED!!!!!
→ Opposite seen during autumn
QUESTION: what is the main hormone involved with eating?
Ghrelin (peptide hormone)
QUESTION: When would ghrelin circulation levels be at its highest?
Before mealtimes and night
QUESTION: In obese people…
Ghrelin is lower before eating
But following eating, their ghrelin levels do not drop
QUESTION: what is the main cycle involved with reproduction behaviour in animals?
Mammalian oestrous cycle
What did Beall & Tracy (2013) find?
They asked women what t-shirt they were wearing and found that when at high risk of conception, they were more likely to wear pink or red shirts, compared to when they were at a low conception risk.
What did Miller et al. (2007) find?
They recorded tip earnings by dancers in a lap-dancing club, and collected information on hormone contraception and menstrual cycles. The dancers got more tips when they were fertile, and tips were lower for those using the pill.
What hormone has been associated with prosocial behaviours?
Oxytocin
What is the difference between parental and alloparental care?
Parental: you look after your own young.
●Alloparental: you look after the young of others.
What happens if oxytocin receptors in the brain of maternal female rats and female prairie voles are blocked?
Maternal behaviour is inhibited
What did Madden & Clutton-Brock (2010) find?
They injected meerkats with either oxytocin or a saline solution and found increased: guarding, pup feeding, closeness to pups, and communal digging, and decreased aggression - compared to the saline solution group.
But the effects only lasted around 30 minutes.
What behaviours have been associated with oxytocin in rodents/meerkats?
Rodents and meerkats given supplementary doses of oxytocin spend more time in contact with others
●Knocking out oxytocin gene of male mice renders them unable to recognise the scent of previously encountered female
●Infusing brain with oxytocin cures this amnesia
H ow does oxytocin supplementation impact pair bonding of the Prairie vole, and why does this not happen with Meadow Vole?
Oxytocin injections promote pair bonding in the Prairie Vole.
●The Meadow Vole with few Vasopressin Receptors does not have the same effect.
What effects does exogenous OXT administration have? (Bartz et al, 2011)
●Anxiety reduction
●Perceptual selectivity/ Social salience
●Affiliative motivation
What did Kosfeld et al find in their economic trust game?
Those who received oxytocin made transfers 17% higher than the control.
Which social Behaviour is increased with oxytocin supplementation?
Generosity, sensitivity, trust
What happens to oxytocin levels during an orgasm?
Oxytocin increases during an orgasm
What feelings would this evoke?
Contentment ●Reductions in anxiety ●Calmness ●Security ●Indications of pair bonding
What two neuroendocrine protection systems are activated by stress?
Sympatho-adrenergic system (SAS)
Hypothalamic-pituitary-adrenal (HPA) axis
●These systems organise responses to harmful situations
●Involves BIDIRECTIONAL brain-body communication
What are the stages of the stress response?
1.Alarm reaction
●Stressor is perceived by the pituitary-adrenal system
●SAS prepares body for fight or flight
●HPA releases energy stores
2.Resistance Stage
●Body tries to reestablish homeostasis
●If stressor persists, stress hormones/arousal stays high
3.Exhaustion stage
●Prolonged stress leads to illness and exhaustion of resources and body defences
What are the physiological changes accompanying the alarm reaction?
Increase in blood pressure, tachycardia and tachypnoea
What areas are activated by the SAS?
Brainstem nuclei, vagal nerve, adrenal medulla
What does the adrenal medulla do?
Releases adrenaline and noradrenaline into the blood
Noradrenaline stimulates alpha receptors in the muscles. What do these receptors do?
Redirects blood to essential organs, increases blood pressure
What does ACTH do?
Stimulates the adrenal cortex to release cortisol and other steroids
This engages slower, passive coping mechanisms for when fight or flight is ineffective.
Which one of these is an example of neurogenic stressor?
a. Dangers associated with novel environment
b. Inflammatory signals
c. Somatic nociceptors
d. Financial worries
A
What does Yerkes–Dodson Law not show?
Stress is negative
