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Cognitieve Neuropsychologie > HC 1 > Flashcards

HC 1 Flashcards

1
Q

What is neofrenology?

A

The use of brain scans to diagnose personality.

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2
Q

What kind of neurons are found in grey and white matter?

A

Neurons with cell bodies are found in grey matter of the cerebral cortex and the subcortical structures. Neurons with their axons are found in white matter. It is white due to myeline.

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3
Q

What is hyperpolarisation?

A

It is when the potential difference is at the the ‘rest’ level again.

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4
Q

What is depolarisation?

A

When the potential difference exceeds the threshold and starts getting more positive, until the action potential is reached.

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5
Q

What is repolarisation?

A

It is when the potential is going back to negative after the depolarisationphase.

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6
Q

What happens at the axon hillock?

A

Potentials are generated at these axon hillocks. Then it gets transported through the axon and ends at the synapses.

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7
Q

What does an actionpotential do?

A

It triggers the delivery of neurotransmitters, so the same process starts in the next neuron.

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8
Q

What is the most simpel signal?

A

It is the sinusoidal oscillation.

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9
Q

What is a frequency?

A

It is the rate in which a signal changes, for example in time.

What time does it take before a whole cycle is run? When a signal is 1Hz, that means the signal goes up and down in one second.

Biological sounds never contain just one frequency, only man-made frequencies have this, which is called a pure tone. Biological sounds have multiple frequencies ranging from slow to fast.

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10
Q

What are the three frequency components?

A

Signals can be cut up into frequency components, which also have certain parameters. These are:

-Frequency
-Amplitude
-Phase

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11
Q

What is an amplitude?

A

How much a signal goes up and down.

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12
Q

What is a phase?

A

When a signal goes up and down.

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13
Q

What is the frequency spectrum?

A

It is the measured limit of frequencies, since it is not limitless.

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14
Q

By what is the highest frequency limited?

A

It is limited by the sampling frequency, which is how much a signal gets measured.

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15
Q

What is the Nyquist sampling theorem?

A

It states that the highest frequency is limited by the sampling frequency:

0.5 x sampling frequency

When timepoints are closer to each other, higher frequency can be measured.

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16
Q

By what is the lowest frequency limited?

A

It is limited by how much time it takes to measure a signal.

1/ amount of second that is needed to measure the signal

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17
Q

What is filtering?

A

It is when you weaken/ mute or rule out a certain part of the frequency spectrum.

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18
Q

What are the three important types of filtering?

A
  1. Low-pass filtering
  2. High-pass filtering
  3. Band-pass filtering
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19
Q

What is low-pass filtering?

A

This is also called smoothing. Low or slow frequencies are untouched, while higher or faster frequencies are weakened or filtered out of the signal.

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20
Q

What is high-pass filtering?

A

Higher frequencies may pass, while lower frequencies are weakened or filtered out of the signal.

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21
Q

What is band-pass filtering?

A

This type of filtering has a certain range (band) in which frequencies may pass through. All frequencies lower or higher than this range gets weakened or filtered out.

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22
Q

How molecular communication on a small and bigger scale?

A

Small scale: Changes in the cellmembrane due to the movement of chemical substances and molecules in and out of neurons.

Bigger scale: Looking at energyconsumption of all processes that are involved in neural activity. More energy consumption means more blood supply. This can be used to obtain a fMRI signal.

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23
Q

What does hemodynamics mean?

A

It is the blood supply that is changed based on the energy needs at a specific moment, so it changes over time. More energy consumption also means more blood supply.

24
Q

Why is the amplitude of potential differences not a good predictor of energy consumption?

A

An actionpotential is a passive chain of events that does not require a lot of energy. If an action potential is generated, then the rest becomes an automatic process where not a lot of energy is required. This gives us no information.

25
Q

How does the amount of actionpotentials correlate with energyconsumption of a neuron even though the amplitude of potential differences is not a good predictor?

A

The recovery of the rest potential requires energy. That is why the energy consumption of a neuron can correlate with the amount of actionpotentials. Pre- and postsynaptic factors such as deposit of neurotransmitters and balancing of restpotential require energy.

26
Q

What is clustering?

A

It is the tendency of neurons with the same functional characteristic to lay close to each other physically.

The more clustering there is, the more the average signal of many neurons correspond with the signal of an individual neuron, so a better signal.

The sensitivity of a non-invasive technique is dependent on the amount of available clustering.

27
Q

What are the three dimensions neuroscience techniques have?

A

-Temporal
-Spatial
-Invasiveness

28
Q

What is temporal resolution?

A

The smallest unit of time that can be seperated by a technique.

29
Q

What is spatial resolution?

A

The smallest unit of space that can be determined.

30
Q

What is invasiveness?

A

The majority of the techniques are either fully invasivess or not at all. It is the distance between neural tissue that sends out the signal and the detector.

31
Q

What kind of techniques are used on humans and what are the consequences?

A

Only non-invasive techniques are used on humans. This has a disadvantage: there are no methods available with a high spatial resolution combined with a high temporal resolution.

32
Q

What is histology?

A

This is an invasive method where the brain gets cut up into pieces. These pieces get processed chemically to visualise the structures of interest.

This was a standard method to study the anatomy of brains in non-human like animals.

It has a high spatial resolution.

33
Q

What are hemodynamic correlates?

A

Changes in oxygen supply in blood and tissue, bloodstream and blood-volume.

34
Q

Why is the temporal resolution of hemodynamic imaging worse in comparison to electrical imaging?

A

It is due to the slowness of hemodynamic events. The more we further go into the chain, the distance exist between location and timing of the neural activity and events caused by neural activity. It is roughly 16 seconds to develop.

35
Q

Spatial resolution varies, but range is smaller for hemodynamic signals than electrical ones, why?

A

This is because hemodynamic imaging does not have the resolution of single-unit recordings.

36
Q

What are some examples of hemodynamic techniques?

A

-Optical imaging
-fNIRS
-PET
-fMRI

37
Q

What is optical imaging?

A

It is an invasive technique. Columnar structure is visible.

It uses the effect of oxygen supply of tissue on the reflection of light that shines through tissue.

38
Q

Techniques measuring electrophysical activity mostly have a good temporal resolution, but vary greatly in spatial resolution, what is it influenced by?

A

-The distance between electrode and the source of the signal. The farther the distance, the bigger the volume gets sampled by the electrode.

-Tissue laying in between. Signal then gets worse.

-Non-invasiveness, the highest frequencies cannot be picked up, so you are limited to lower frequencies, so you obtain a part of information of the signal.

39
Q

What are patch-clamp recordings?

A

Optimal spatial resolution is obtained by using this technique. This is the only technique that measures changes in membranepotential reliably with limited disruption.

A hollow tube is filled with electrolyto solution and a recording electrode that is connected to an amplifier that gets brought in conctact with a membrane of an isolated cell.

40
Q

What are extracellular single-unit recordings?

A

With this technique, an electrode gets placed in the cortex, as close as possible to a single neuron to pick up the action potential of that neuron.

A condition is that the electrode has a strong resistance, so that only signals from close by are picked up.

41
Q

Which techniques can be used if electrodes have a bad resistance?

A

Multi-unit recording or local field potentials

42
Q

What are multi-unit recordings?

A

It is a technique in which you record multiple close by units at the same time.

It is often used with a high-pass filtering, because action potentials are characterized by fast changes in the membrane potential, so the high frequencies are kept.

43
Q

What are local field potentials (LFPs)?

A

It measures and processes the same signals as multi-unit recordings, but it uses low-pass filter, so information about slow changes can be picked up.

44
Q

Why are techniques such as patch-clamp, extracullular singe unit recording, multi-unit recording and LFPs risky, even though it gives the best spatial resolution?

A

It is risky in living organisms, because they require for the durameter to be opened up. The durameter protects the cortex against infections.

45
Q

What are intracranial recordings?

A

This technique requires the skull to be opened, but only to place the electrodes on top of the durameter, so it stays intact unlike with other techniques. This makes sure that the electrode gets placed closed to the neural tissue without any disruption.

46
Q

What is a consequence not opening the skull for a technique?

A

Spatial resolution is bad, making it very difficult to measure individual brain areas. This also leads to measures often relating to activity of multiple brain areas and systems.

47
Q

What is EEG?

A

It stands for electroencephalography.

Electrodes are placed on the head and every electrode measures the combined signal of a great volume of the brain. This leads to overlapping areas, creating correlations between measured signals.

EEG is characterised by a P1 peak and a decline around 170ms (N170) that has a higher amplitude when shown a face.

48
Q

What are scalp ERPs?

A

ERPs are event-related potentials. They are small changes in the scalp-recorded electroencephalogram time-locked to the onset of an event such as a sensory stimulus or a motor act.

49
Q

Why does EEG and ERP have low spatial resolution and what are the consequences?

A

The signal reflects activity of many cm of the brain and does not display the same selectivity as loose neurons.

Due to low spatial resolution, components do not differ between different faces and is anatomic localisation weak.

Also, the relation between neural activity on level of the neuron on EEG/ERP signal is complex.

50
Q

What are the peripheral measures?

A

-Skin conductance
-Heart activity
-Muscle activity
-Eye measures

51
Q

What is skin conductance?

A

It is an index for (sympathetic) arousal intensity with affective or cognitive processing. It changes a lot over time and the differences between indivuals is great.

52
Q

What is heart activity?

A

It is heart rate, but also heart rate variability and blood pressure.

The heart rate variability measures the influence of the peripheral nervoussystem on the heart.

Blood pressure is a measure of stress.

It can be called ECG for short.

53
Q

What is muscle activity?

A

It is a tool to read affective states. For example, if a person is more concerned with something, there is more activity in the face muscles.

It is called EMG for short.

54
Q

What is eye activity?

A

You can measure either eye movements or pupildilation.

It can also be called EOG for short.

55
Q

How is eye movement measured?

A

With:
-Saccades= they are verty fast and no new information is obtained during them.

-Fixations= information is often obtained during this.

56
Q

How is pupildilation measured?

A

It is an indication of intense emotion arousal regarding nice and not so nice stimuli and experiences.

It is dependent on light, but also reflects mental workload and processing of emotional stimuli.

Cognitieve Neuropsychologie (13 decks)

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