methods

Question 1

what is microscopic anatomy

Answer 1

• brain segmented according to appearance in microscope
• combined with comparative neuroanatomy
• appearance reflects type of cells
• type of cell sometimes correlates with function
• studies restricted to small number of brains

Question 2

what is a limitation of microscopic anatomy

Answer 2

• time consuming

Question 3

what is the rule of brodmann areas

Answer 3

if they look different they probably have a different function

Question 4

how many layers is the outer layer of the brain organised into

Answer 4

6

Question 5

what is the function of layers 1-3 of the cortex

Answer 5

integration

Question 6

what is the function of layer 4 in the cortex

Answer 6

receives input of sensory information

Question 7

what is the function of layers 5 and 6 in the cortex

Answer 7

output to the other parts of the brain

Question 8

what is transcranial magnetic stimulation

Answer 8

• stimulator is placed above scalp, contains a coil of wire
• brief pulse of high electric current fed through the coil
• result - magnetic field - wth flux lines perpendicular to the plane of the coil
• magnetic field induces field perpendicular to magnetic field
• electric fields lead to neuronal excitation within the brain

Question 9

advantages of transcranial magnetic stimulation

Answer 9

non-invasive, painless, safe stimulation of human brain cortex

Question 10

what are the ways to measure effects of TMS

Answer 10

• motor cortex stimulation
• occipital cortex stimulation
• somatosensory cortex stimulation
• auditory cortex stimulation
• frontal cortex stimulation

Question 11

what happens in motor cortex stimulation

Answer 11

• activates corticospinal neurons trans-synaptically
• record motor EPS
• record silent period in contracted target muscles
• causes twitches

Question 12

what happens in occipital cortex stimulation

Answer 12

• excitatory effects e.g. phosphenes (flashes of light), inhibitory effects; suppression of motion perception and letter identification

Question 13

what happens in somatosensory cortex stimulation

Answer 13

• may elicit tingling, block the detection of peripheral stimuli
• can modify somatosensory evoked potentials

Question 14

what happens in auditory cortex stimulation

Answer 14

• interpretation of results challenging, loud coil click

Question 15

what happens in frontal cortex stimulation

Answer 15

effects on subjects mood - potential for therapeutic use

Question 16

what is the TMS study on crossmodal plasticity in the brain

Answer 16

• blind people can learn to read braille superior tactical perception
• blind persons visual cortex is known to be activated during braille reading

Question 17

what is an example of TMS

Answer 17

virtual lesions

Question 18

what is virtual lesions

Answer 18

• repetitive TMS for temporary inhibition of brain areas, fully reversible; virtual lesion (for a few minutes, subjects behave as if after a brain lesion)
• leading to errors during braille reading
• error rates depend on site of virtual lesions

Question 19

advantages of TMS

Answer 19

• temporal resolution in millisecond range
• virtual lesions in subject may be better defined than lesion in patient
• short duration of experiment minimises risk of plasticity
• repeated studies in the same subject
• group studies with standardised experimental set up
• study double dissociations; stimulate or temporarily disrupt different cortical regions during one task, one region during different tasks

Question 20

disadvantages of TMS

Answer 20

• spatial undersampling
• only cortical areas are accessible (only one area at a time)
• auditory cortex stimulation problematic
• loud coil, click, need ‘sham stimulation’

Question 21

what is EEG

Answer 21

• measuring electrical activity in the brain
• neurons aligned perpendicular to cortical surface, dendrites closer to the surface and axons closer to the white matter
• synchronous firing of large neuron populations can be recorded non-invasively
• EEG generated by postsynaptic potentials

Question 22

what is the berger effect

Answer 22

when you open your eyes rhythmic waves disappear because the brain is suddenly busy processing visual information

Question 23

what are alpha waves

Answer 23

• when your eyes are closed and you are relaxed, the brain produces steady, rhythmic waves called alpha waves

Question 24

what is beta

Answer 24

most evident frontally, dominant rhythm when subject is alert, eyes open

Question 25

what is alpha

Answer 25

occipital maximum, dominant when subject is relaxed with eyes closed, blocked by opening the eyes or by onset of mental effort

Question 26

what is theta

Answer 26

slow activity, rare in adults when awake but perfectly normal in children and sleep

Question 27

what is delta

Answer 27

dominant rhythm in infants and stages 3 and 4 of sleep

Question 28

what is event-related oscillations

Answer 28

stimulus or task related changes in EEG oscillations, in terms of frequency or amplitude; temporal resolution tens to hundreds of milliseconds

Question 29

what is event-related potentials

Answer 29

waveforms defined in terms of latency relative to an event such as a sensory stimulus; obtained through time-locked averaging of EEG; temporal resolution tens of milliseconds

Question 30

what is ERPs as averaged EEG epochs

Answer 30

- method used to find a specific brain response int the constant background noise of the brain - record EEG trials, time locked to the event of interest - each trial contains ERP and voltage fluctuations that are not time locked to the event - under certain assumptions - averaging increases the signal-to-noise ratio of the ERP signal

Question 31

what artifacts are to be excluded from averaging

Answer 31

- movement of the eyeballs - muscle activity

Question 32

what are exogenous ERPs

Answer 32

automatic responses of the brain, controlled by physical properties of stimulus - sensory evoked potentials - elicited whenever modality-specific sensory pathway is intact - influenced by intensity/frequency of stimuli - highly important for neurological diagnosis, less so for psychological research

Question 33

what are endogenous ERPs

Answer 33

reflect interaction between subject and event (attention, task-relevance, expectation) - response to omitted stimulus

Question 34

what are mesogenous ERPs

Answer 34

semi-automatic but modulated by cognitive processes

Question 35

how does N1-P2 wave change based on external environment

Answer 35

- intensity - as sound gets louder, the amplitude of the N1-P2 wave increases - rate of presentation - if the time between stimuli is slowed down, the brain's response actually becomes larger

Question 36

what is cognitive modulation

Answer 36

your thoughts can change the signal

Question 37

what experiment supports cognitive modulation

Answer 37

- subject hears tones in both ears but is told to attend to only one ear - when subjects focuses on the tones of the left ear, the N1 response recorded from the scalp is significantly larger compared to when they are ignoring that ear - this shows that the effect of selective attention emerges in the brain as early as 100 milliseconds after the stimulus occurs

Question 38

what happens when a person hears a specific tone

Answer 38

the brain produces a large negative wave called the N100 about 80-100 milliseconds later

Question 39

what is the inverse problem

Answer 39

no single mathematical solution to determine the internal source just by looking at surface data

Question 40

what is the oddball paradigm experiment

Answer 40

- researchers use a passive auditory paradigm to trigger this response - standard tones - a frequent sound played 90% of the time - deviant tones - a rare sound played only 10% of the time that differs in pitch, intensity and duration - passive state - the subject is not paying attention to the sounds, they are doing something else

Question 41

what is mismatch negativity

Answer 41

a specific brain response that occurs when your brain automatically detects a break in a repetitive pattern of sounds. - it is a component of mesogenous ERPs meaning it happens in the middle stage of brain processing

Question 42

what is the 'classic' P3 task

Answer 42

- you are told to actively count a rare sound while ignoring a frequent one - the P300 appears once the brain has finished evaluating the stimulus. if the sound is hard to categorise, the wave length takes longer to appear - the wave is largest when the task-relevant sound is very rare. if the rare sound becomes more common, P300 shrinks

Question 43

what is the 'novelty' P3 task

Answer 43

- response to unexpected sounds for which you have no template of memory - it reflects the brain's orientating response - the moment your attention is pulled toward something totally new or surprising - unlike the classic P3n, which is the strongest at the back, this one is strongest at the front of the head

Question 44

what is the omitted stimulus P3

Answer 44

- happens when nothing occurs - if your brain is expecting a rhythmic sound and one beat is skipped, your brain will still produce a P300 wave at the exact moment the sound should have happened - this proves the P300 is an internal process, not just a reaction to a physical sound

Question 45

what is the N400

Answer 45

a negative-going wave that peaks approximately 400 milliseconds after a person encounters the word. it is endogenous because it isn't just a reaction to hearing a sound, it reflects the brain's internal effort to make sense of a word without context

Question 46

amplitude vs meaning in N400

Answer 46

the height of the wave is directly proportional to how much a word does not fit the context

Question 47

grammar vs meaning in N400

Answer 47

the N400 specifically tracks semantics, not syntax. even if the sentence is grammatically perfect, the N400 will fire if the meaning is bizarre

Question 48

what is the process of movement related potential

Answer 48

- readiness potential - slow rising negative wave that precedes a voluntary movement - timing - the signal begins to climb several hundred milliseconds before the actual onset of voluntary movement - location - the signal is strongest in the brain hemisphere contralateral to the limb that is about to move - post-movement - after movement occurs, the brain produces a reafferent potential, which is the feedback signal from the limb back to the brain

Question 49

what is contingent negative variation

Answer 49

- the S1-S2 paradigm - happens when a person receives a warning stimulus, followed by an imperative stimulus that requires a response - O-wave - the initial reaction to the warning light - E-wave - the steady buildup of electrical negativity as the person waits for the tone to happen

Question 50

what is magnetoencephalography

Answer 50

- electrical activity in the brain generated magnetic fields - magnetic fields can be measured outside the head - skull is transparent to magnetic fields - MEG sensors - no contact with scalp - better spatial resolution that ERP/EEG - millisecond temporal resolution - MEG responses to stimuli through averaging - requires very low noise environment or magnetic shielding