Hoofdstuk 3 Flashcards
Representations
Properties of the world that are manifested in cognitive systems (mental representation) and neural systems (neural representation)
Why is the relationship between a mental representation and a neural one unlikely to be straightforward?
The response properties of neurons (and brain regions) correlate with certain real-world features; it is not copied inside the head
Single-cell recordings (or single-unit recordings)
Measure the responsiveness of a neuron to a given stimulus (in terms of action potentials per second)
Electroencephalography (EEG)
Measurements of electrical signals generated by the brain through electrodes placed on different points of the scalp, useful for the relative timing of cognitive events and neural activity
Event-related potential (ERP)
The average amount of change in voltage at the scalp that is linked to the timing of particular cognitive events, it is common to link the rate of change of the EEG signal to cognitive processes
Reaction time
The time taken between the onset of a stimulus/event and the production of a behavioral response, also referred to as response time
Hoe werkt single-cell recording?
Het actiepotentiaal wordt direct gemeten, er wordt een kleine electrode geïmplementeerd in de neuron zelf of aan de buitenkant van het membraan (invasive), het aantal ‘spikes’ per seconde wordt gemeten, wordt vooral gedaan bij dieren, bij mensen alleen bij een operatie
Multi-cell recordings (multi-unit recordings)
The electrical activity (in terms of action potential per second) of many individually recorded neurons recorded at one or more electrodes
Grandmother cell
A hypothetical neuron that just responds to one particular stimulus (for example the sight of one’s grandmother)
What are three different types of representation that may be found at neural level?
- Local representation: All the information about a stimulus/event is carried in one of the neurons (grandmother cell)
- Fully distributed representation: All the information about a stimulus/event is carried in all the neurons of a given population
- Sparse distributed representation: A distributed representation in which a small proportion of the neurons carry information about a stimulus/event
Rate coding
The informational content of a neuron may be related to the number of action potentials per second
Temporal coding
The synchrony of firing may be used by a population of neurons to code the same stimulus or event
Hoe werkt EEG?
Het signaal komt van de postsynaptische dendrieten ipv. van de axonen en het actiepotentiaal, elektrische signalen van het brein worden opgenomen door electrodes geplaatst op de buitenkant van je hoofd (non invasive), er moeten meerdere neuronen synchronisch vuren om het signaal op te kunnen pikken, deze moeten parallel liggen aan elkaar
Wat is signal-to-noise ratio?
Bij een EEG, de ruis die ontstaat doordat niet alleen de neuronen worden opgenomen die activiteit tonen bij een event, maar ook de activiteit van de neuronen er omheen
Dipole
A pair of positive and negative electrical charges separated by a small distance, electromagnetic field
