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Cognitive and Biological Psychology > Week 20 > Flashcards

Week 20 Flashcards

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1
Q

Phrenology

A
  • correlation of a person’s brain anatomy and skull shape with their behaviour/personality
  • dividing the skull into sections of different psychological traits that are said to correlate to the brain + depending on the size of that region that determines how much of that trait you have as an individual
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2
Q

Modern methods for investigating the brain

A
  • examining the effects of brain damage (brain injury/lesions or simulations in the lab, e.g. stimulating electrodes/TMS)
  • physiology (recording electromagnetic activity of single of populations of neurons - EEG and MEG)
  • imaging (visualising the structure and/or activity of neurons on the whole brain - neuronal staining techniques, MRI, CT/PET scans)
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3
Q

Natural brain injuries and lesions

A
  • used to determine the correlation of the loss of a specific cognitive function with the area of brain damage
  • e.g. Phineas Gage (frontal lobe damage); corpus callosotomy (split brain patients); Broca’s aphasia (link with Broca’s area to sentence structure processing)
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4
Q

Stimulating localised brain activity (invasive)

A
  • in lab animals or open-brain surgery
  • stimulating electrodes used to pierce the skull to activate certain areas of the brain
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5
Q

Stimulating localised brain activity (non-invasive)

A
  • in healthy patients
  • transcranial magnetic stimulation (TMS) can be used to excite/inhibit neurons by externally applying time-varying electromagnetic fields generated by a coil located above the head
  • used to induce a temporary “lesion” to see the outcome in a patient (e.g. see if inhibiting a certain brain region specifically inhibits a certain activity in a patient)
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6
Q

Single-cell recordings

A
  • single neuron behaviour can be examined through the use of microelectrodes which impale the cells of interest
  • a nano lead (a submicron scale electrode) is implanted into an intracellular axon or extracellular axon membrane
  • records neural activity of a single neuron but doesn’t stimulate it
  • e.g. single-cell recordings in hippocampus to see if cells respond to one single stimulus (such as a specific person)
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7
Q

Electroencephalography (EEG)

A
  • used to measure electrical brain activity on the scalp (recording the electromagnetic activity of a population of neurons rather than just single ones)
  • sensitive to postsynaptic dendritic currents generated by populations of neurons that are active in synchrony
  • placement of electrodes on the scalp is frontal (F), central (C), parietal (P), occipital (O) and temporal (T)
  • very strong time-based resolution (less than 1 ms) but a rather poor spatial resolution (as it is difficult to tell specifically where the sources of signals are within the brain)
  • useful for diagnosing epilepsy (characterised by an abnormal spike and wave discharge)
  • can also use EEGs to assess brain waves during a specific repeated cognitive task to assess event-related potentials to assign different cognitive domains to activities
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8
Q

EEG Rhythms (delta)

A
  • 0.5-4 Hz
  • most prominent frontally in adults and posteriorly in babies
  • seen normally in babies and in sleeping adults
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9
Q

EEG Rhythms (theta)

A
  • 4-7 Hz
  • seen normally in young children
  • in adults, seen in drowsiness or sleep arousal or meditation
  • excess theta waves for your age represents abnormal activity (e.g. due to focal subcortical lesions)
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10
Q

EEG Rhythms (alpha)

A
  • 8-12 Hz
  • bilaterally in the posterior regions but higher on the dominant side
  • emerges with closing of the eyes and with relaxation
  • attenuates with eye opening or mental exertion
  • abnormally diffused and not responsive to external stimuli alpha waves in a coma
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11
Q

EEG Rhythms (beta)

A
  • 12-30 Hz
  • most evident frontally
  • linked to motor behaviour, attenuated during active movements
  • absent or reduced in areas of cortical damage
  • dominant rhythm in patients who are alert or anxious or who have their eyes open
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12
Q

EEG Rhythms (gamma)

A
  • 30-100 Hz
  • represent binding of different populations of neurons together into a network for the purpose of carrying out a certain cognitive or motor function
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13
Q

Magnetoencephalography (MEG)

A
  • recording of the magnetic fields produced by electrical currents in the brain using arrays of SQUIDs (superconducting quantum interference devices)
  • it is much more expensive but can be more reliably localised to sources within the brain (due to signal being unaffected by the skull, meninges etc. like EEGs are)
  • also more sensitive to activity at sulci, whereas EEGs are sensitive to both sulci and gyri activity alike
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14
Q

Neuronal staining techniques

A
  • in order to stain a slice, the brain cannot be alive (not useful for dynamic imaging)
  • e.g. Golgi stain method: randomly stains 5% of neurons, making them visible against the background of neural “chaos”
  • e.g. Myelin stains: taken up by fatty myelin that wraps around neurons and thus identifies neural pathways (by visualising white matter)
  • e.g. Nissl stains: identify cell bodies of neurons (visualising gray matter)
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15
Q

Structural imaging

A
  • uses the fact that different types of tissue (e.g. skull, gray matter etc.) have different physical properties in order to construct detailed static maps of the brain
  • used to scan alive human brains to view dynamic images
  • used to see what is going on in the brain but not too much is revealed about the specific function of different regions
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16
Q

CT (computerized tomography) scans

A
  • contrast dye is injected into the blood with a series of X-rays sent out from different angles
  • the X-rays are combined into a series of horizontal sections of the brain
  • X-ray absorption varies with tissue density (bone absorbs most = white; CSF absorbs least = black; gray/white matter = grey)
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17
Q

MRI (magnetic resonance imaging) scans

A
  • a strong magnetic impulse is applied, with energy released by molecules in the tissue released as a result of the pulse being measured
  • differently charged molecules respond differently to the pulses, hence the energy signals reveal brain structures with different molecular compositions (e.g. showing haemorrhage or tumour)
  • brain images plotted with such measurements so more precise and detailed than CT scans
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18
Q

Functional imaging

A

measures neuronal activity (e.g. brain activity associated with cognitive processing)

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19
Q

fMRI (functional magnetic resonance imaging) scans

A
  • measures activation by detecting the increase in oxygen levels (active neurons consume more oxygen)
  • also measures the ratio of deoxyhaemoglobin and oxyhaemoglobin in the blood in different areas (BOLD/blood oxygen level dependent contrast response)
  • change in BOLD response over time is known as the haemodynamic response function so you can localise active points (high spatial resolution)
  • peaks 6-8 seconds after the stimulus event and is extended over time (limits the temporal resolution of fMRI for pinpointing the exact time of the activity)
  • useful for cognitive research to pinpoint exact locations for brain activity (indicating active regions in a specific activitiy)
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20
Q

PET (positron emission tomography) scans

A
  • measures local bloodflow into a brain region, measuring levels of glucose/fuel to the brain
  • radioactive tracer injected into bloodstream
  • slow technique with very imprecise temporal resolution (tracer takes up to 30 seconds to peak) but has good spatial resolution
  • fMRI is better as it does not require radioactive tracer and PET scans have worse temporal and spatial resolution
  • but PET is faster and sensitive to the whole brain (whereas fMRI such as near sinuses are harder to image)
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21
Q

Internal rhythms

A
  • circannual (yearly) and circadian (daily) rhythms are endogenously generated, although can be modulated by external cues/zeitgebers like sunlight and temperature but also keep existing without these
  • e.g. Mimosa plants still open and close their leaves in the same cycle as it does in darkness as it does in sunlight - suggesting rhythms are generated internally
  • human body generates its own circadian cycles of activity and inactivity (including clear patterns of brain wave activity, hormone production, cell regeneration etc.)
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22
Q

Mechanisms of the biological clock

A
  • when the brain is awake: neurons in the upper pons produce acetylcholine –> passed onto the thalamus (relay station) –> signals to cortex to maintain the brain in the conscious/awake state; also neurons in the pons produce noradrenlaine/dopamine etc. –> signals to hypothalamus –> signals distributed across cortical areas
  • when the brain is tired: SCN in hypothalamus signals to activate VLPL neurons in thalamus –> GABA released and sent to hypothalamus and pons –> inhibits excitatory signals to the cortex –> cortex shuts down and loses consciousness (i.e. is asleep)
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23
Q

Suprachiasmatic nucleus (SCN)

A
  • present in the hypothalamus and termed the master clock
  • main control centre of the circadian rhythms of sleep and temperature
  • generates circadian rhythms even when disconnected from the rest of the brain/body
  • modified donor rhythms persevere in the recipient’s brain (SCN by itself is sufficient to perserve its own properties)
  • the SCN’s zeitgeber is light (provided by neurons in the retina) so that when a light stimulus is present this resets the body’s biological clock
  • also SCN corresponds to pineal gland that secretes melatonin (that is also influenced by light hitting retinal neurons)
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24
Q

Polysomnography

A
  • used to study the stages of sleep
  • EEG (brain wave activity) + eye tracking + breathing rate + amount of oxygen in the blood
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25
Q

Awake brain wave activity

A

dominated by beta waves

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26
Q

Drowsy/relaxed brain wave activity

A

dominated by alpha waves

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27
Q

Stage 1 sleep

A
  • light sleep stage with fleeting thoughts
  • slow eye movement and minimal muscle activity
  • dominated by slower theta waves
28
Q

Stage 2 sleep

A
  • light sleep
  • contains sleep spindles (0.5+ second long bursts of 10-15 Hz waves) and K-complexes (sharp biphasic waves)
29
Q

Stage 3/4 sleep

A
  • slow wave, deep sleep
  • heart rate, breathing rate and temperature all go down (as does brain activity and muscle tone)
  • hard to awake from this state
  • dominated by slow high amplitude delta activity
30
Q

REM sleep

A
  • heart rate and blood pressure increase (as does brain activity, dreaming and partial paralysis)
  • more brain activity than other sleep stages (activity in the pons, limbic system, parietal/temporal cortex, amygdala - quite involved during threatening/stressful situations; but decrease in PFC - less involvement of planning and executing actions in a sensible way, motor cortex and primary visual cortex)
  • REM sleep begins with PGO waves (transmitted from pons to lateral geniculate nucleus in occipital lobe)
  • dominated by sawtooth/alpha-like waves
31
Q

Dreams

A
  • considered an altered state of consciousness (a form of experience that departs significantly from the normal subjective experience of the world and the mind)
  • feeling emotion more intensely, dream thought is illogical, however we experience uncritical acceptance and also have difficulty remembering the dream when it is over
  • hypnagogic state = presleep consciousness
  • hypnopompic state = postsleep consciousness
32
Q

Activation-synthesis hypothesis (dreams)

A
  • believes that dreams are the brain’s attempts to make sense of the information reaching it (mind attempts to make sense of random neural activity during sleep)
  • based mostly on the haphazard input originating in the pons
33
Q

Neurocognitive hypothesis (dreams)

A
  • believes that dreams originate mostly from the brain’s own motivations, memories and arousal
  • the stimulation often produces peculiar results as it does not have to compete with normal visual input and does not get organised by the PFC
34
Q

Brain arousal systems

A
  • pontemescenphalon, hypothalamus and basal forebrain (contain neurons that promote wakefulness and others that promote sleep)
  • locus coeruleus is active in response to meaningful events (facilitates attention and new learning)
  • orexin (maintains wakefulness and is released in the lateral and posterior nuclei of the hyopthalamus)
  • during sleep, enhanced GABA release limits neuronal activity and blocks the spread of activation
35
Q

Sleep cycles throughout the night

A
  • throughout the night, there are typically five 90 min long sleep cycles of non-REM and REM sleep
  • non-REM proportion is higher in the early hours (11pm-3am) and REM sleep increases across the course of the night (3am-7am)
36
Q

Pattern of sleep across different ages

A
  • newborns (very little time in awake state, high level of REM sleep may help brain development)
  • children (more time in slow-wave sleep than adults, intensity of this electrical activity is linked to how well they learn)
  • teenagers (reduced REM sleep, a lack of slow-wave sleep can hamper learning ability)
  • adults (awake for longer throughout the day, reduced REM sleep, slow-wave sleep declines as the ageing brain loses gray matter from the medial frontal cortex, making adults less able to lay down new memories)
37
Q

Sleep deprivation

A
  • affects thermoregulation (over or underheating of body temperature occurs)
  • immune system (initial response to disease and restoration are disrupted)
  • metabolism (conversion of stored resources into energy is impaired)
  • memory (sleep is critical for integrating memories into an ordered framework and assimilating new memories with older semantic knowledge; shown that place cells show an exact memory replay of an event that occurred during the day being repeated during sleep to consolidate it)
  • e.g. total sleep deprivation (TSD) in rats - all TSD rats died within 11-32 days, showed to have a debilitated appearance and lack of immune response, weight loss etc.
  • non-REM sleep deprivation leads to impairment of declarative memory; whereas REM sleep deprivation leads to impaired consolidation of learned motor skills
38
Q

Irregular sleep

A
  • too short + long sleep and sleep issues are associated with poorer cognitive function
  • sleep deprivation decreases attention and working memory, especially vigilance but also auditory and visuospatial attention and reaction time tasks
39
Q

Insomnia

A
  • inadequate sleep may be due to shifts in circadian rhythm (e.g. trying to sleep whilst body temp rises)
  • estimated prevalence in 10-35% of the population in Western Europe
  • may also be due to noise, stress, pain, diet, medication etc.
40
Q

Sleep apnea

A
  • inability to breathe during sleep
  • leads to sleepiness during the day, impaired attention, depression and sometimes heart issues
41
Q

Narcolepsy

A
  • frequent unexpected periods of sleepiness during the day (REM sleep intruding into wakefulness)
  • caused by lack of hypothalamic cells that produce and release orexin
  • treated with stimulant drugs (e.g. Ritalin)
42
Q

Periodic limb movement disorder

A
  • repeated involuntary limb movements that can cause insomnia and mostly occur during non-REM sleep
43
Q

REM behaviour disorder

A
  • vigorous movement during REM periods leading to acting out during dreams
  • inability to paralyse limbs that normally happens during REM sleep
44
Q

Night terrors

A

abrupt, anxious awakening from non-REM sleep

45
Q

Sleepwalking

A
  • normally occurs in deep sleep stages 3/4 early in the night
  • more common in children but can occur in adults suffering from sleep deprivation or stress
46
Q

Differences in sleep across species

A
  • all mammals and birds need sleep
  • some utilise unihemispheric slow-wave sleep (e.g. dolphins so they can still resurface regularly to breathe) but it is mainly bihemispheric
  • fish, reptiles and amphibians have periods of inactivity
  • for most animals, sleep conserves energy during times when the animal is in an inactive period
  • animals increase sleep during food shortages (hibernation)
47
Q

Auditory system

A
  • primary domain for two sensory experiences most uniquely human (speech/language and music)
  • how the brain translates sensory information into a perceptual representation of our environment
48
Q

Sound

A
  • the periodic compressions of air, water or another medium
  • in some spaces, air is rarefied and in other it is compressed
  • bouncing back of sound waves is called echo
  • hearing is the detection of sounds and constructing a model of the world based on this
  • especially in a noisy environment, many sounds overlap at one time so the brain needs to use incoming sensory input and prior knowledge about sounds to separate them into different streams
49
Q

Auditory cortex

A
  • located in the temporal lobe in Heschl’s gyrus (Brodmann’s areas 41 & 42)
  • right hemisphere specialises in rhythmic sound and music; left hemisphere specialises in language
50
Q

Perception of sound

A
  • outer ear (pinna) first captures the sound and amplifies it by funneling it into the smaller auditory canal
  • middle ear contains the eardrum which collects the tiny vibrations
  • eardrum transmits the vibrations to the ossicles (hammer, anvil and stirrup)
  • their lever action transfers the vibration to the cochlea, via the oval window
  • vibrations bend the hair cells on the Organ of Corti (3 rows of OHCs and 1 row of IHCs)
  • this opens potassium and calcium channels to depolarise cells and set off signals in the neurons
  • exciting cells of the auditory nerve (part of the 8th cranial nerve)
51
Q

Auditory pathway

A
  • signal is first carried from the ear along auditory nerve
  • first relay is the ispalateral cochlear nuclei in the brainstem
  • here signal is decoded based on duration, intensity and frequency and most of the signal crosses over to the contralateral side of the brain
  • second relay in the brainstem is the superior olivary nucleus in the pons
  • third relay is in the inferior colliculus of the midbrain
  • final relay occurs in the medial geniculate body of the thalamus
  • then projects into the auditory cortex
52
Q

Sound intensity

A
  • corresponds to how much air fluctuation (compression/rarefraction) a sound creates, i.e. the energy in the sound
  • e.g. large vibration of speaker –> creates a lot of energy –> intense (loud) sound
  • also correlates to amplitude
  • intensity is measured in decibels (logarithmic scale)
  • there is a non-linear correspondence between intensity and loudness (so we can determine whether a sound is louder or quieter but not whether it is exactly twice as loud etc.)
  • intensity is encoded by neuron firing rate within the auditory cortex (neurons fire more frequently as sound intensity grows)
53
Q

Hearing loss above what intensity

A

90 dB

54
Q

Sound frequency

A
  • correlates to the number of air compression/rarefraction cycles per second that the object creates
  • perceptual correlate is pitch (but again there is not a linear correspondence)
  • in reality, most sounds we hear our complex tones (combinations of many frequencies)
55
Q

Encoding frequency

A
  • frequency is encoded by the Place code (different locations in the cochlea have different elasticity in the basilar membrane so correspond to different sound frequencies) –> tonotopic organism
  • cells close to the apex respond to very low sounds; nearer the base respond to very high sounds
  • primary auditory cortex is also tonotopically organised to correspond to the cochlea (more anterior = lower pitch; more posterior = higher pitch)
  • for sounds < 200 Hz: lower frequencies are encoded by firing of individual neurons (temporal coding) and intensity is encoded by number of firing neurons (spatial coding)
56
Q

Normal human hearing range

A

20 Hz - 20 kHz

57
Q

Stereophonic hearing

A
  • the placement of our ears on opposite sides of our head
  • due to timing/intensity difference of sound reaching each ear we can perceive the location of sound
  • also integrate this with visual orienting (produce an enhanced percept of a situation)
58
Q

Conductive hearing loss

A
  • results from damage to the ear drum or ossicles in the middle ear
  • failure to transmit sound waves to the cochlea
  • can be corrected by medication (e.g. if due to inflammation of the middle ear), surgery or sound amplication from hearing aids or bone conduction
59
Q

Bone conduction

A
  • sound is used to vibrate the mastoid bone
  • cochlea receives the vibrations and turns them into electric signals to pass to the auditory cortex as usual
  • allows hearing issues in outer or middle ear to be bypassed
60
Q

Sensorineural hearing loss

A
  • damage to part of the cochlea/hair cells of the inner ear
  • can be conginetal, as a result of disease or by repeated exposure to loud noises
  • can be corrected by cochlear implants
61
Q

Cochlear implants

A
  • surgically implanted electronic devices which receive sound signals via a microphone and digitally convert them to coded electrical signals
  • communication coil used to transmit these signals through the skin to the implant
  • electrical pulses transmitted along the electrode array to stimulate specific locations on the cochlea (for frequency perception as normal)
  • delivers signals to auditory nerve and interpreted as sound by the auditory cortex
62
Q

Tinnitus

A
  • sound perception within the ear in the absence of external input
  • can be ringing due to abnormal patterns of activity sent to the brain by a damaged ear (e.g. due to ageing, sound damage) –> cured by surgically severing the auditory nerve that corresponds to the ringing frequencies
  • or ringing can be caused by activity in the auditory cortex even in the absence of sound –> not curable surgically, but CBT can be used to help patients ignore the sound
63
Q

Auditory hallucinations

A
  • MRI activations during auditory hallucinations in schizophrenia show ventricular enlargement
  • also fMRI shows changes in brain activity even in absence of external input within the right inferior colliculus, right superior temporal gyrus (primary auditory cortex) and right thalamus
  • can also be caused by brain damage (e.g. Shostakovich had damage to left temporal lobe so heard random sounds which inspired his music)
64
Q

Perfect pitch

A

ability to name and reproduce a musical note without external reference

65
Q

Relative pitch

A

ability to identify intervals between given tones

66
Q

Amusia (tone deafness)

A
  • present in birth in 4% of the population or acquired as a result of brain lesions
  • receptive: inability to recognise familar melodies, read musical notes and detect out of tune notes
  • expressive: lack of ability to sing, write musical notes and play an instrument

Cognitive and Biological Psychology (8 decks)

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