L4: Sensation and Perception (+ brain devices) Flashcards
what are ways we can study the brain in humans? list 4
EEG
PET
MRI + fMRI
Lesion studies
what are two possible faults for each technique of studying the brain
spatial resolution:
- how clearly we can distinguish between brain regions
- Low SR = lines blur not as clear
- High SR = can see exactly where everything is
Temporal resolution:
- resolve differences in the brain activity over time
- high TR = you can find the brain activity changing per millisecond
- low TR = cant see signaling in brain as fast
1 Brain technique: Electroencephalography (EEG)
what, why, how, record on graph?, sleep/brain wave connection
- what: measures the electrical activity in the brain -the activation of synapses (not firing rate)
- why: useful in arousal, consciousness + epilepsy studies
- how: measures the neurons via electrodes that are placed above
- record: potential difference (volts) over time (seconds)
- sleep:
awake: low amp, high freq
sleep: high amp, low freq
REM: low amp, hig freq - breaks the rules
use it to diagnose sleep disorders
EEG: how good is the temporal res and spatial res?
Great temporal resolution (biggest advantage)
* Millisecond scale
* Great for measuring rapid changes in arousal/consciousness (regular EEG) and rapid cognitive processes (ERP)
Poor spatial resolution (biggest disadvantage)
* Difficult to determine which specific areas are active
* Deeper brain areas cannot be measured
useful for studying fast signaling, bad at locating regions
2 Brain technique: Positron Emission Tomography (PET)
what, why, how, example with glucose
what: measures activity in the brain using a synthetic radiotracer that is injected in the subject
how: This radiotracer reacts with tissue in the brain; this reaction produces a signal that can be measured with specialized equipment
why:
Two general purposes:
* Measuring metabolic activity
* Characterizing distribution of specific substances
glucose:
* If the radiotracer is similar to glucose (such as Fluorodeoxyglucose (18F)), it will be distributed in the same way (i.e. to active neurons)
* Signal differences between brain regions reflect differences in glucose demands (+ neuronal activity)
PET: how good is the temporal res and spatial res?
implication in psychology?
Decent spatial resolution
* Better than EEG but worse than MRI
Poor temporal resolution
* Difficult to resolve rapid changes in neural activity
- Due to its resolution issues, PET is no longer preferred as a structural/functional measure in psychology
- It does have other very important uses in neuroscience and medicine (but you won’t need to know these)
3 Brain Techniques: MRI/fMRI
what, MRI and disorders/MDD, how (fMRI), fMRI for behavior and disorders, con for fMRI
what:
MRI is for assessing structure–one of the best. fMRI, can be used for assessing function.
MRI and MDD:
Major depressive disorder (MDD) is associated with structural anomalies:
- orbitofrontal cortex and hippocampus are smaller
- lateral ventricles are larger
- by using an MRI we can figure out how these treatments work
- MRIs cannot be used to diagnose disorders by itself
how (fMRI):
- neurons use glucose + oxygen
- after blood delivers oxygen it becomes deoxygenated
- Oxygenated and deoxygenated blood have different magnetic properties which can be measured
- If you measure blood oxy/deoxy ratio in a given area, you’ll have a correlate of neuronal activity in that area
fMRI for behavior and disorders:
- brain activity differs in different tasks, personality characteristics, and mental health disorders
- fMRIs can help us see if certain concepts are involved in an area
con for fMRI
- there are many areas in the brain for many roles
- cannot infer a single cognitive process for it
fMRI: how good is the temporal res and spatial res?
Great spatial resolution (great for studying brain structure)
* Best out of techniques we have covered today
* Can be ‘paired’ w/other techniques (e.g. PET)
Decent temporal resolution
* Better than PET (arguably), not as good as EEG or MEG
* Lag of seconds between activity and signal is still evident
- Popular technique for cognitive neuroscience, but should be interpreted with care
4 brain technique: lesion studies
what, examples, cons
what: a brain lesion can be associated with deficits in behaviours.
examples:
- Patient HM – Removal of Hippocampus + adjoining areas to cure epilepsy; Impaired declarative memories
- Phineas Gage – Lesion of Frontal Lobe; Impulsivity + Impaired Social Behavior
Cons:
* Lesions rarely specific (many brain areas involved)
- like HM had many areas removed not just the hippocampus
- Other behaviors could be impaired but not measured
- we cant measure all variables, so there may be more impairments that we don’t know
- Cases are very rare (often N = 1)
- Is it repeatable? Or was it chance?
- Difficult to make a conclusive argument based on them
- Not experimental, no control for other variables (e.g. individual differences, life history)
what is sensation
receiving, collecting and amplifying information from the environment (initial phase; involves sensory organs)
- taking in the stimuli
- information processing
what is perception
interpreting/organizing this information so that we may understand + react to it (later phase)
- higher order brain stems
- output is response
- automatic judgments that are made without your consent
what are sensory organs
organs that contain specialized receptors attached to neurons, these neurons send signals to the brain
what are the 5 structures of the sensory network
1. Sensory organ
2. Sensory receptors, which are linked to neurons
3. Sensory nerve
4. Thalamus*
5. Specific cortical areas
what are the 5 elements in the vision network (brain to eye pathway)
- Eye
- Photoreceptors
- Optic nerve
- Thalamus (Lateral Geniculate)
- Occipital (or Visual) cortex
what is vision
processing the stimulus of light
what are rods and cones in the eye
Rods
* Dense in periphery
* useful in dim light/darkness
* less involved in color
Cones
* Dense in the fovea
* operate in bright light
* role in color perception
what colors do the three types of cones associate with? what was an earlier thought about colors and cones?
different types of cones respond to different types of light
Max color processing:
- S cone: blue light
- M cone: green/yellow
- L cone: yellow orange
- earlier people thought: if we saw red light we would use the L cone than the others.
what is the trichromatic color theory?
what is another name for it?
- Also called Young-Helmholtz Theory
- Every color is a combination of three independent color
signals (and perhaps the activity of three cones) - Analogy: Color Slider in Imaging Software
what is the opponent process color theory?
Processing of signals in pairs, contrasting color signals interact (Blue v. Yellow, Red v. Green, Black v. White)
what is spectral sensitivity
perception of the brightness of a color
what is contrast enhacement
edges are exaggerated
what is color constancy
there are adjustments in the lighting so we may see colors differently
how do we hear?
what does amplitude and frequency indicate?
- Pressure vibrations in the air
- amplitude: The magnitude of air pressure (in molecule density)
- Related to loudness
- Changes in air pressure (from high to
low) are cyclic (they repeat over time) - frequency (Hz): The amount of cycles per second
- Related to pitch
what is the hearing pathway?
Eardrum > Ossicles > Cochlea > Hair Cells > Vestibulocochlear Nerve > Thalamus (Medial Geniculate) > Auditory/Temporal Cortex
what is the vestibular system involved in
our perception of balance
explain the sense of touch
- Important for social development
- Communicates warmth, caring and support
- Affected in autism
do the sensory receptors in our skin differ per sensation? if so how?
different receptors in our skin activate differently depending on the sensation
ex. touch is a fast stimulation whereas pain is a slow stimulation
what is proprioception
- Sense of the relative position of one’s body and the strength of effort employed in movement
- Achieved through input from specialized neurons in the skin, joints, bones, ears and tendons
- Neurons communicate compression + contraction of muscles
explain pain
what is the response associated?
- Private experience associated with injury OR the feeling that injury has occurred
- Adaptive response, allows us to identify danger + withdraw from it
- Loss of pain associated with injury and early mortality
- Involves a broader neural network (also includes Prefrontal cortex, Cingulate Cortex + Insula)
what are the 5 tastes (gustation)
sweet
salty
sour
umami
bitter
what is the taste pathway
Taste cells > Bipolar neurons > Cranial nerves (7, 9, + 10) > Brainstem Structures > Thalamus (VPM) > Primary Gustatory Cortex (Insula)
what is the taste map theory and what is wrong with it
theory that different regions on your tounge correspond with different tastes: Definitely disproven
what is a supertaster bud theory and whats the consensus on it
some people have more tast buds making them a super taster
- currently debated
what is olfaction
whyis it important? what is it used for?
- sense of smell
- Important for survival
- Threat warning (e.g. detect fire + spoiled food)
- Social behavior (recognition of friends, attraction to mates)
- Notably different than other pathways in terms of processing (specifically, involvement of the thalamus)
- Compared to other senses, poorly studied and poorly understood
what is the olfactory (smell) pathway
Begins with olfactory receptors that sends signals to the olfactory bulb responding to odorant molecules in the air
Pathway:
Bipolar Receptor > Glomerulus > Olfactory nerve > Primary Olfactory Cortex (Pyriform) > Secondary Olfactory Cortex (OFC)
what is ‘the taste experiences’
??? that we can distinguish between tastes
- sweet, sour, etc.
what is the Speechreading and the McGurk effect
speechreading (lipreading): we can understand what someone is saying based on how their lips move and their body language
McGurk effect: the idea that auditory and visual perceptions can intersect and cause confusion in how we process the stimuli.
ex. we hear a speaker say ‘ba’ but we see someone say ‘ga’. our brain may interpreate it as ‘da’ – a completley different sound
what is synesthesia
when your senses merge. ex. we can taste the color red. or we can hear the smell of ‘vanilla’
what is a sensory mismatch
when our senses mismatch and we get confused and our cognitive abilities are hindered. like the McGurk effect.
ex. when spinning on a chair (touch) and we get dizzy (visual), our senses don’t align
what is sensory competition
when our senses compete for what is more important when provided with different types of stimuli.
prioritize what is more important
- can lead to sensory mismatch
what is the detection thershold / absolute threshold
- detection threshold: the weaker the signal, the harder is it for us to detect it
- absolute threshold: refers to the lowest stimulus intensity (in units) at which we can correctly detect the stimulus >50% of the time (i.e. above chance)
- stimuli lower than this threshold are not detectable – but still important
what are subliminal signals and what are some examples. what are some cons to it?
defn: signals not achieving conscious awareness (too weak, ambiguous, and/or presented too quickly)
- Briefly flashing text of religious significance at a level below conscious awareness, for example, can marginally affect cheating behaviors
- Though research shows subliminal effects are real, it also suggests they are weak and brief
- advertising using this is ineffective.
- your response to subliminal advertising changes when you are made aware of it
what is response vs awareness with respect to stimuli
what is blindsight
- idea that the awareness of stimuli and response to stimuli may arise via separate pathways
- either we conduct 1) responses before awareness
- or 2) responses without awareness might be possible (ie. blindsight)
describe the two types of innaccuracies of stimulus detection. what is the system that explains this inaccuracy.
- Though we report many sensory stimuli, we are not always accurate in doing so
- We may report stimuli when none are present (e.g. report a noise not there)
- We may fail to report stimuli that are present (e.g. fail to report a smell that is there)
- Inaccurate reports could be linked to sensory problems or situational biases
- Risk and reward
explain the stimulus detection graph in words
the two biases and the two axes
bias for detection:
if the stimulus is present and the perciever says ‘yes’ then that is correct
if the stimulus is absent and the perciever says ‘yes’, that is a false alarm
bias against detection:
if the stimulus is present and the preciever says ‘no’ then that is incorrect.
if the stimulus is absent and the perceiever says ‘no’ that is a correct rejection
what is just noticeable difference (JND)
other name? what is an example?
- Also termed the difference threshold
- defn: The point (in stimulus units) at which you can just barely discriminate a change in a stimulus
- For example, if you’re trying to discriminate weights and JND = 4 kg…
- You could distinguish weights differing by ≥ 4 kg
- You could distinguish 1 kg from 5 kg
- You could NOT distinguish 1 kg from 3 kg
what is the weber-fencher law
what is the formula and graph
- JND is generally proportional to stimulus intensity
- This law attempts to describe our ability to detect changes in the property of a stimulus
- y-axis = change in background intensity (l, difference threshold)
- x-axis = background intensity
- x/y = K (constant slope)
- As K is constant, we can expect that the JND (change in I) will increase any time stimulus intensity (I) increases
defn consiousness. what is a part of unconsiousness and consiousness. why is consiousness importnat? what plays a role in processing information?
- defn: Our subjective awareness of ourselves and our environment
Unconsicous:
Automatic behaviours
Implicit memories
Conscious:
Controlled behaviour
Explicit memories
- Consciousness is fundamental to our sense of identity, free will and morality
- Recall (from L01) that most processing is thought to be unconscious processing
why do we need sleep?
5 main points with two having sub-points
- Maintenance of the brain (clearance of waste) and restoration of injured tissue
- Ontogenetic development of the brain (from childhood to adulthood)
- Learning + memory processes
- Energetically favorable
- Dreaming
what are the sleep stages and the frequency ranges?
Sleep Stages and Frequency of brain waves as measured by EEG:
REM: similar to wakefullness and dreaming = theta and beta waves
Resting = eyes closed not asleep = alpha waves
NREM1 = light sleep = theta waves
NREM2 = deeper sleep (considered the first actual sleep stage) = theta waves
NREM3 = deep sleep = delta waves
NREM4 = deep sleep = delta waves
REM = rapid eye movement
NREM = non-rapid eye movement
frequency ranges:
Beta: >13 Hz
Alpha: 7-13 Hz
Theta: 4-7 Hz
Delta: 1-4 Hz
Explain the sleep in the elderly
with age we decline in REM, deep, and normal sleep.
greatest sleep latency (we take longer to sleep), more arousal periods (likely awakenings).
how much sleep should we get (population based)? what is a misconception about this number?
- Mean for adults is ~ 7–8h
- Recommendations and social perceptions are that this is the ‘normal’ level
- No ‘magic number’ as factors such as exercise, stress + genetics all matter
what are some variations in sleep-wake cycle?
what are chronotypes? what factors effect? cause/effect in kids?
- variations in sleep wake cycles are called chronotype.
- Many factors effect: genetics, age and gender
- early bird, night owl
- Shifts evident in adolescence; may be exacerbated by increasing use of electronic devices
- Sleeping patterns of adolescents have led to recommendations about school start times (i.e. no earlier than 8:30 am)
what are some early birds and night owls personality and preformance tendencies?
- Morningness = better academic performance
- but eveningness = greater cognitive ability
Eveningness = poorer mental health
- Chronotype –> personality
- morningness: agreeableness and conscientiousness
- eveningness: neuroticism (emotional instability) in certain cases (females, adolescents), sensation-seeking
dreams: defn, types, neurocognitive theory, REM and NREM
- Narrative with ‘experiential resemblance to waking life’
- Typically aversive (>64%), rarely happy (<18%) or sexual (<10%)
- Neurocognitive theory: Increase in complexity w/age
- REM dreams (~80%) tend to be emotional, illogical and
have sudden plot shifts - NREM dreams (~20%) are more thought-like, repetitive and centered around daily tasks
why do we dream (3 theories)?
Dream Protection Theory
* Sexual + aggressive instincts are transformed into symbols that represent wish fulfillment; interpretation required
- we dream about our desires
- con: these types of dreams are rare
Evolutionary Theory
* Dreams about threats to reproductive success, plan solutions
- we may dream something and then rethink our reality
Activation-Synthesis Theory
* Dreams are an attempt by the brain to interpret random activity
- we get so many signals when sleeping so our brain tries to put it to use
- con: if dreams were due to random input, dreams wouldnt repeat
defn hypnosis? probability of working, and the best candidates?
- defn: Trance-like state, generally induced
- ~20% highly responsive, equal amount unresponsive
Best candidates:
* willing/eager
* open to new experiences
* able to focus their attention
* capable of fantasy
* show conformity, obedience and suggestibility
- Pre-selection effects are common in public demonstrations
what are the two theories of hypnosis? how does the public view this? what is hypnosis used for?
- Dissociative theories and socio-cognitive theories (better-supported) have been proposed
Dissociative theories = involves a split in consciousness, leading to a separation of awareness and control. person responds to hypnosist
socio-cognitive theories = hypnosis induces a social influence. person internalizes the social setting via cognition. person responds to hypnosist by conforming to the social influence
- Not viewed fondly by the legal community
- Information under hypnosis inadmissible, false memory risk
- Used in combined therapies for anxiety + pain
what are near death experiences (NDEs)? why do they vary amoung people? how can you statistically study it? how can you trigger it? what are some common features of it? what are its consequences?
- defn: Experience associated with death or impending death
- Though NDEs vary between individuals of different backgrounds, particular –> similar characteristics are often present, in an order
- May be studied using the Greyson NDE scale
- Aspects of NDEs can be triggered with drugs (ketamine, DMT, opioids), brain stimulation or hypoxia
common features:
- peacefullness
- outofbody experience
- altered time perception
- unearthly environment
- happiness
- bright light
- point of no return
NDE tend to be peaceful and dreams tend to be aversive
- Consequences
- Increased spirituality
- Less scared of death
- Greater social attitude
what is meditation? how prevelent is it? what is the stats on meditating individuals? what can it treat?
- defn: An activity in which an individual either trains the mind and/or induces an altered state of consciousness
- Meditation is widely practiced and has shaped culture, religion and medicine
- ~8% of adults have meditated (1.6% of children)
- Certain meditation styles – such as mindfulness meditation – may help treat anxiety, depression and chronic pain disorders
defn other unusual experiences:
hallucinations and deja vu
prevelance, defn, how/why occurs?
Hallucinations (10 – 25% of people)
* Realistic perception in the absence of external stimuli
* Abnormal brain activity is a common explanation (sensory deprivation, hypoxia or drugs)
* Characteristic of certain disorders (e.g. Schizophrenia)
Déjà vu (~66% of people)
* “Already seen”
* May be due to temporal lobe anomalies (creating false feelings of familiarity) or prior similar experiences (justified feelings of familiarity, but you cannot remember past event)
