HC1 Introduction

Question 1

Cognitive neuropsychology

Answer 1

The study of the relation between structure and function of the brain and specific cognitive functions (e.g. language, memory, attention, …)

Question 2

Cognitive neuropsychology research

Answer 2

• By investigating these cognitive processes in normal healthy people.
• By investigating the breakdown of these processes in brain-damaged individuals (as a result of acquired brain damage or as a result of a developmental disorder).

Question 3

Brain enthusiasm

Answer 3

• Brain scans as evidence in court of law
• Brain scans might be overinterpreted by laypersons.
• Good progress for several neurological syndromes, but less progress for psychiatric and mental syndromes.

Question 4

Neurons

Answer 4

Contain with cell bodies in grey matter of cerebral cortex and subcortical structures

Question 5

Axons

Answer 5

Contained by white matter

Question 6

Neuron without input

Answer 6

Without input (at rest), cell membrane of a neuron has
an electrical potential difference between in- and outside of -70 mV

Question 7

Post-synaptic potential

Answer 7

Is determined by integrating input of many synapses at the dendrites. It can hyperand depolarize.

Question 8

Neural communication

Answer 8

o Input neurons (through neurotransmitters): action potentials over time
→ Membrane potential of post-synaptic neuron depolarizes or hyperpolarizes
o Over time, membrane potential of post-synaptic neuron changes in function of input it receives = signal

Question 9

Simplest signal

Answer 9

Sinusoidal oscillation

Question 10

Frequency

Answer 10

Rate of change of signal, e.g. in the time dimension
o 1 Hz = completing a full cycle (going up & down) in one second
o Biological signals never contain just one frequency

Question 11

Complex signals can be decomposed into..

Answer 11

Frequency components
Each has a particular frequency (e.g., 1 Hz, 2 Hz, 3 Hz, …)

Question 12

Amplitude

Answer 12

How much it goes up and down

Question 13

Phase

Answer 13

When it goes up and down

Question 14

Frequency spectrum

Answer 14

Measured range of frequencies

Question 15

Highest frequency

Answer 15

▪ Limited by sampling frequency
▪ ½ * sampling frequency (Nyquist sampling theorem)

Question 16

Lowest frequency

Answer 16

▪ Limited by how long the signal is measured
▪ 1 / number of seconds measured

Question 17

Filtering

Answer 17

Attenuating or excluding certain part of measured frequency spectrum (low-pass, high-pass or band-pass)

Question 18

Spectrogram

Answer 18

Strength of each signal component at each moment in time

Question 19

Electrophysiological changes are connected to other kind of changes: at a SMALLER scale

Answer 19

Movement of chemical substances and molecules
▪ E.g. depolarization: influx of Na+, repolarization: outward current of K+
▪ E.g. calcium concentration high in electrically active neurons → two-photon calcium imaging

Question 20

Electrophysiological changes are connected to other kind of changes: at a LARGER scale

Answer 20

Hemodynamics
▪ Blood supply is adjusted to current energy needs

Question 21

Energy consumption

Answer 21

o Electrophysiological events require energy
o Amplitude of potential changes not necessarily best predictor of energy consumption
▪ Action potential
o Restoring resting potential requires energy → energy consumption of neuron could correlate with number of action potentials
o Pre- and post-synaptic factors (e.g., neurotransmitter release) also require energy
o Exact energy distribution to different processes can vary (species, neuron type)

Question 22

Action potential

Answer 22

Passive chain of events that does not consume much energy

Question 23

Maps in the brain - Clustering

Answer 23

Noninvasive methods cannot achieve single neuron resolution
▪ Methods with highest spatial resolution still average signal from many neurons.

Question 24

Maps in the brain - Neurons of similar functional properties are clusrered together

Answer 24

o The more clustering, the more the averaged signal from many neurons corresponds to the signal of the individual neurons → sensitivity of a noninvasive imaging technique depends upon amount of clustering present
o Clustering on different spatial scales
▪ Topographic areas: for example the somatosensory homunculus but also for auditory or occipital information

Question 25

Temporal resolution

Answer 25

The smallest unit of TIME that can be differentiated by a method

Question 26

Spatial resolution

Answer 26

The smallest unit of SPACE which can be resolved

Question 27

Invasiveness

Answer 27

majority of methods are either fully invasive (skull needs to be penetrated) or not invasive at all
o Invasive methods: used mostly in animal studies
o Non-invasive methods: also used for humans

Question 28

Measuring brain structure

Answer 28

• Histology
• Structural magnetic resonance imaging (MRI)

Question 29

Histology

Answer 29

o Cutting brain in pieces (e.g. slice of mouse brain)
o Process chemically for visualization of specific structure
▪ Makes us able to differentiate between the 6 brain layers, and between different structures in the brain

Question 30

Structural magnetic resonance imaging (MRI)

Answer 30

o Investigation of anatomy in individuals
o Anatomical localization of functional findings
o Relate anatomical structure to differences between participants in e.g. behavior, disease classification

Question 31

Measuring hemodynamics

Answer 31

• Changes in blood and tissue oxygenation, blood flow, and blood volume
• Temporal resolution of hemodynamic imaging is poorer compared to electrical imaging due to slowness of hemodynamic events
  o hemodynamic events take 16 sec to develop
• Spatial resolution varies strongly (but range smaller than for electrical signals):
  o (invasive) optical imaging: columnar structure visible
  o (non-invasive) fNIRS: several cm

NIRS -> PET -> fMRI

Question 32

Measuring electrophysiological activity

Answer 32

• Spatial resolution
• Quiroga et al. (2005): single unit recordings in epilepsy patients
• Pitcher et al. (2011): EEG study

Question 33

Spatial resolution, affected by

Answer 33

o Distance electrode and source of the signal
o Intermediate tissue (e.g. skull)
o Noninvasiveness: highest frequencies cannot be picked up
▪ Different frequency bands contain very different information!

Question 34

Quiroga et al. (2005): single unit recordings in epilepsy patients

Answer 34

o Theory that in every person there is only on neuron that responses to a picture of their grandmother. For every different face a different neuron responds.
o Very exciting, but rare, ethical constraints, and difficult experimental control
→ less invasive techniques in humans

Question 35

Pitcher et al. (2011): EEG study

Answer 35

o Signal of EEG-electrodes on back of the head, averaged across many trials of viewing faces (red) or chairs (blue)
o Amplitude of N170 & P1 is stronger for faces versus chairs
o Due to low spatial resolution of EEG these components do not differentiate between Aniston, Pitt, …, and anatomical localization is poor

Question 36

Peripheral measures

Answer 36

Always good to measure peripheral data, in addition to the variables you want to measure
- Skin conductance
- Heart activity
- Muscle activity
- Eye measures

Question 37

Skin conductance

Answer 37

o index of (sympathetic) arousal intensity in affective or cognitive processing
o highly variable, difference between subjects is huge

Question 38

Heart activity

Answer 38

o heart rate
o heart rate variability: measures influence of PNS on heart
o blood pressure: measure of stress

Question 39

Muscle activity

Answer 39

o Facial EMG (electromyography) as a tool for inferring affective states

Question 40

Eye measures

Answer 40

o Eye movements: good measure of visual attention
▪ Saccades (fast movements of the eyes): Very fast (20-40 ms), no new information is acquired during saccades
▪ Fixations : Information acquisition occurs (mainly) during fixation
▪ Proudfoot et al. (2017) → Eye tracking in ALS patients
Trail making test A & B: connect the dots -> 1-2-3 / 1-A-2-B-3-C etc.
o Pupil dilation
▪ indicative of intense emotional arousal toward both pleasant and unpleasant stimuli and experiences
▪ Bradley et al. (2007): pupil dilation reflects SNS activity Pupil diameter larger for pleasant & unpleasant conditions than for neutral