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| Question | Answer |
| What is needed for Haemodynamic measures? | Activity need not be synchronous, orientation of activity of neurons is irreverent. Changes in activity detectable only with change in metabolic demand, signal amplitude influenced by magnitude and duration |
| What are the main three reasons why ERPs should be measured? | Allows to identify when cognitive functions operate, relatively cheap and easy method with which to split cognitive functions, good for work with babies as they don't produce overt responses |
| What do EEG's do? | It compares voltage in one electrode to another. |
| How is the EEG signal relative in space? | As it represents the difference between two electrodes |
| What are the two kinds of EEG measurement? | Bipolar and monopolar |
| What are bipolar EEG recordings? | Voltage difference within pairs of electrodes is measured (often used in medical practices) |
| What is the monopolar EEG recording? | The voltage at each electrode is measured against a single reference electrode. Usually chosen as a neural point, however no point is neutral on the head so no true monopolar measurement |
| Where can the reference electrode be in monopolar recordings? And what can be reconstructed from monopolar recordings? | Anywhere, and biopolar recordings. |
| What is a steady rate visual evoked potential? | Fast rate visual stimulation on a certain frequency. The brain responds to stimulation with a continuous oscillatory response on the same frequency. Can be recorded via cortex. |
| What are steady rate visual evoked potential used for? | Psychophysical measures; absolute and different thresholds, contrast sensitivity, aculty. |
| What are strength and weakness of steady-state visual evoked potentials? | Advantage, does not need much time. Disadvantage yields only yes/no answer |
| What is Transient Visual Evoked Potentials? | Stimulation is slower, signal to noise ratio is improved by averaging EEG segments time-locked to stimuli |
| What are the advantage and disadvantage of transient visual evoked potentials? | Advantage, gives information about time-scource processing in terms of components, but needs many trails to reduce noise |
| What is the main difference between Event-related potentials and transient visual evoked potentials? | ERPs are when higher levels of processing are studied. |
| What are the steps to constructing an experiment? | Debrief and relax participant, measure participant's head, prepare the cap,insert electolyte gel, do study, wash participant's head and answer any questions |
| What are the two types of noninvasive measurements of brain activity? | Haemodynamic and electrophysiological |
| What does the haemodynamic measures record, and why isn't it often used? | Brain blood supply, and because it is very expensive |
| What does electrophysiological measures record, and why is it more often used? | Electromagnetic fields, and because it isn't that expensive |
| What activity is detectable on the scalp? | Activity from some neuronal populations |
| How do neurons create an electromagnetic field? | When the neurons in populations are oriented in the same direction and are activated simultaneously |
| What is a closed electromagnetic field? | Loads of neurons firing in different directions |
| What is an open electromagnetic field? | Loads of neurons firing in the same direction |
| Why are EEGs used over MEGs? | MEGs are more expensive, and do not tell you much more than EEGs |
| What are the measures collected from EEGs? And what are they? | Time-locked measures, and event-related potentials, and event-related magnetic fields |
| What are the three assumptions of nature of electrical activity of the brain? | Electrical sources are dipoles, dipole generates an electric current corresponding temporally and spatially to brain activity, dipoles align in large groups in region of brain activity producing a dipole |
| What are inpedences, and what are examples? What problem do they create? | Things which block measures. Thick skulls, mengies, skin, muscles. Makes a measure never perfect |
| What is measured with an EEG? | Post-synaptic potentials of pyramidal cells which are aligned perpendicular to the surface of the cortex, signal is deflected by skull bone and skin. |
| What are the steps of signal analysis? | Referencing, rejection of artifacts (irrelevant), segmentation, baseline correction, averaging at individual and then group level. Statistical analysis in differences of amplitutes |
| What are areas of postnatal brain development? | Neurogenesis and apoptosis, axonal and dendritic growth, synaptogenesis, myelinization, hemispheric specialization, interactive specialization. |
| What is the brain considered as in terms of being an organ? | Of being multiple organs, due to multiple brain systems |
| What are the four characteristics of synaptic density? | Spreading, pruning, slow decline during adulthood, faster decline during old age |
| What are event-related potentials? | Change in brain activity over time due to function to stimuli, recorded from several sites on the scalp, real time representation of how an event is processed |
| How can EEG's measure changes in synaptic density? | Follow an inverted U- function, similar changes in event related potential amplitudes, increase during infancy and then decrease |
| Who do EEG's measure myelinzation? | There is a decrease of latencies |
| What is a problem that arises when using EEG? | Not sure where the activity is coming from, just the sum of all activity |
| What inferences can be made from an EEG/MEG? | Identify that a function is engaged, distinct functions, temporal organisation |
| What inferences can be made from an fMRI/PET? | Identify that a function is engaged, distinct functions, neural substrate of function |
| How do EEG's measure synaptic efficiency/synchronization of networks? | Less slow wave activity, more defined peaks |
| What does decreasing variability of latencies mean in an EEG? | Less smearing of components, shorter latencies lead to a greater amplitudes. |
| How are anatomical changes reflected in EEG results? | Changes in the topography of components |
| Specialization of areas/networks, is shown in EEGs as? | More localized activation |
| Who conducted an EEG study comparing infants and adults? | Thierry (2005) |
| What was the differences in background activity between adults and infants found by Thierry? | Strong delta- and theta-activity in infants which can hardly be filtered out completely |
| What was the differences in age dependence between adults and infants found by Thierry (2005)? | In terms of weeks in early infancy |
| What was the differences in maturation between adults and infants found by Thierry (2005)? | Pre-terms differ from full-term born infants |
| What was the differences in inter-individual variability between adults and infants found by Thierry (2005)? | Much larger in infants |
| What are three general differences found by Thierry (2005) between adults and infants? | Differences in amplitude and latency, sometimes in polarity, and in topography |
| What is needed for the electrophysiological measure? | Activation must be synchronous and neurons must have an open field. But activity need not be extended in time, signal sensitive to changes in both timing and amplitude of activity |
| What are ways to overcome artefacts? | Manual rejection, central attractors in visual studies |
| What are ways to overcome trail loss? | Video recording, breaks, presentation suitable for children |
| How do you overcome the fact instruction is not possible? | Passive paradigms, infant just sits and watches |
| How do you make infants more cooperative? | Warm up, toys, distraction during preparation. |
| What must studies do to compensate for infant's short attention spans? | Test many infants, and have limited number of conditions per study. Also short presentations |
| How can you prevent parents being a distraction, via skin contact, behavioural influence, etc? | Instructing them to do nothing |
| What are the restrictions that developmental neuroscience studies have? | Need interesting stimuli, passive paradigms, certain age groups are difficult, limited number of conditions per study, within-subjects design |
| How much referencing should there be? | Average amount. |
| What does rejection of artifacts lead to? | Reduction of trail number, decrease of signal to noise ratio |
| How many artifact-free trials must a participant have to be accepted? | 10 or more |
| What are the advantages of using EEG? | Quick preparation, low impedances, no behavioral response needed, applicable with very young infants |
| What are the problems with using EEG? | Artifacts, trial loss, instruction not possible, sometimes lack of compliance, limited attention span, only short representation possible, parents, limited trials |
| What are artifacts? | Movements, eye movement, vocalizations, in short irrelevant brain activity |
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