Brain and cognition (year one) Flashcards
What is an automatic interpretation?
- brain automatically recognises objects, even if they do not exist (if it looks like x, it is x)
- What are info processing systems?
a system that has specific channels to process info to produce a conscious representation
what is the order of info processing systems?
- input, mechanisms, output
What levels of explanations does a theory need to cover?
- behavioural indicators, functional explanation, biological explanation
- what does our interpretation of reality depend upon?
our knowledge
What percentage of cells in the brain are neurons?
10%
Describe the structure of a neuron
- Soma containing nucleus, ER
- Dendrites
- Axon wrapped in Schwann cells
- Nodes of Ranvier in myelin sheath gaps
What is myelination?
Schwann cells wrapping around the axon
What are nodes of Ranvier?
gaps in the myelin sheath, which conduction passes between
What is the resting membrane potential?
-70mv
What is depolarisation?
positive sodium ions flow into the cell as ion channels in dendrites open
What affect do excitatory and inhibitory neurotransmitters have on ion channels?
- EN : depolarizes (sodium ions flow in)
- IN : hyperpolarises (chloride ions flow in)
What is the CNS made up of?
Brainstem, midbrain, forebrain
What is the brain stem made up of?
Spinal cord, medulla, pons, cerebellum
What is the midbrain made up of?
Tegmentum, tectum
What is the tegmentum made up of?
red nucleus, substantia nigra, reticular formation
What is the tectum made up of?
superior colliculi, inferior colliculi
What is the forebrain made up of?
diencephalon, telencephalon
What is the diencephalon made up of?
thalamus, hypothalmus, pituitary gland
Describe the structure of the brain
- two hemispheres, connected by corpus callosum
- hemispheres seperated by longitudinal fissure
What does the cerebrum do?
thinking, learning,emotion, consciousness
What does the medulla do?
respiration, swallowing , vomiting, vasodilation
What does the pons do?
controls sleep/arousal
- connected to the cerebellum
What does the cerebellum do and what does it consist of?
- fine motor skills
- accounts for 10% volume in brain
- 50% brains neurons there
What does the superior colliculus do?
rapid eye movements
What does the inferior colliculus do?
auditory reflexes
What is the tegmentum?
lots of nuclei
What does the reticular formation do?
supervises sleep / arousal of cortex
Which nuclei in the reticular formation releases serotonin?
raphe nuclei
Where do the cranial nerves leave from?
midbrain
What does the substantia niagra do?
voluntary action
What cells are damaged in the substantia niagra in Parkinson’s disease
- dopaminergic cells
What does the thalamus do?
- relay station/ control station
What is the medial geniculate nucleus?
structure between inner ear/ primary auditory cortex
What is the lateral geniculate nucleus?
relays between eyes and primary visual cortex
What does the hypothalamus do?
- four Fs
- feeding, fighting, flighting and sex
What does the pituitary gland do?
- monitors body growth, endocrine glands
- connected to hypothalamus
What does the HPA axis do?
Part of fight or flight response
What is the telencephalon?
- a neocortex with four lobes
What does the telencephalon consist of?
basal ganglia, limbic system, cerebral cortex
What does the basal ganglia do?
regulates movement that is a timed action
- nuclei on side/ top of thalamus
What does the basal ganglia consist of?
caudate nucleus, putamen, globus pallidus
What does the limbic system consist of?
hippocampus, amygdala, fornix/olfactory bulb, cingulate cortex
What does the amygdala do?
emotional processing (fear condition, strong emotional responses)
What does the hippocampus do?
learning, spatial navigation, long term memory
What does the cerebral cortex consist of?
cingulate cortex, frontal lobe, temporal lobe, parietal lobe, occipital lobe
What does the cingulate cortex do?
detection of conflict, reward anticipation
What does the fornix and olfactory bulb do?
processing of smells (connecting smells to episodic memories
What is the neocortex?
- 3-5mm layer on surface
- mostly made of glial cells (gray matter)
What is white matter?
- bundles of axons connecting neurons in grey matter to other parts of the brain
What are the grooves and buldges called?
grooves - sulci
bulges - gyri
What does the occipital lobe do and contain?
visual inputs from lateral geniculate nucleus, processes visual signals
- • Contains retinotopically organised visual maps
What does the parietal lobe do?
info from visual cortex, generates spatial representations for motor control/ action planning
What is the dorsal pathway?
• Dorsal pathway in the two visual streams model
What are sensory homunculi?
: info from touch receptors, which are processed by “maps” on one side of the lateral fissure
What does the frontal lobe do?
planning, working memory, decision making
What does broca’s area control?
speech production
What does the temporal lobe do?
contains ventral visual pathway
What is the fusiform gyrus?
: bottom of temporal lobe, facial recognition
What is Wernicke’s area?
language comprehension
What is a sensory modality?
: dedicated part of the nervous system that responds to physical inputs
Name the sensory modalities and what they respond to
Visual system : light
Auditory system : vibrations in air
Olfactory system : chemicals in nose
Gustatory system : chemicals in mouth
Tactile receptors : mechanical deformation of skin
Nociception : skin damage
Vestibular system : gravity/ acceleration of the head
What is exteroception?
signals about outside world
What is interoception?
signals about inside body
What is transduction
Converts physical energy into action potentials
What does the JND stand for?
just noticable distance
What is Weber’s law?
- JND increases with stimulus intensity
What scaling does time perception show?
weber- fechner type scaling
What is steven’s power law? give the equation and relationship between variables
p(I) = k(I)^a
P = subjective experience of intensity
I = objective intensity
K = proportionality constant
A = exponent (changes depending on stimuli)
- Relationship between physical stimulus and sensation (often non-linear)
which researchers contributed to gestalt psychology?
- Wertheimer, Koffka, Kohler
what is figure ground segmentation?
we segment the scene into figure and ground
Figure owns the borders, ground doesn’t
Bi-stablility : allow us to feel brain switch between interpretations
What is a monocular cue?
work with one eye shut
What are some monocular cues?
Occlusion : near things occlude far things
Linear perspective : parallel lines converge on vanishing point
Texture gradients : texture becomes finer further away
Height : far things are higher
Motion parallax : Near things move faster than far things
Familiar size : things have a standard size
What is a binocular cue
binocular disparity is useful
Only works over 10s of meters
3D cinemas e.g present different images to each eye and create artificial disparity, making image look very deep (touchable)
What area is sensitive to faces
fusiform face area
What is the phenomena of seeing faces in patterns?
pareidolia
What did Galton find regarding the “average face”
- Galton : average face is attractive
Average face may generate a maximal brain response
May be that average faces are healthy which is adaptive
how did important thinkers see our visual experience?
direct and active
how do we now see vision?
active and indirect
how does sensory transduction occur in the eye?
: light reflected into eye is converted to neuronal electrical signals via photoreceptors
what do ganglion cells do?
: output cells which send signals from optic nerve to the brain
name two types of ganglion cells found in the retina and describe their functions
P cells (parvocellular): carry info about colour and fine detail
M cells (magnocellular) : carry low resolution information and detect motion
describe the fovea
high acuity vision and has highest density of cone cells
describe the blind spot
contains an optic nerve bundle and has rod cells
describe how visual information is altered
- Info from left and right visual fields are transmitted to opposite sides of the primary visual cortex (posterior of brain)
- Information in the upper part of visual field is transmitted to lower part of visual field
what is the pathway of information from the retina?
- Info transmitted from ganglion cells via optic nerve, via laterial geniculate nucleus and superior colliculus
o LGN feeds into primary visual cortex
what is retinotopic mapping?
mapping of visual space onto v1
explain cortical magnification
o Disproportionate amount of cortex represents fovea (centre) causes distortion in the cortical representation
o Cortical magnification : gives high amount of space to centre of images
what are ganglion cell receptive fields? explain on and off cells
- Ganglion cell receptive fields : refer to region in visual field that produces neural response in cell
o ON cell :- ON area is in the centre
light in the centre of receptive field will produce a large neuronal response vs light shone in periphery
o OFF cell : - ON area is in the periphery
Light in periphery (receptive field) will produce a large neuronal response vs light shone in centre
what are alternate names for the primary visual cortex?
area v1, striate cortex
how many layers of cells are in the primary visual cortex?
6 layers of cells
what are ocular dominance columns?
each cell prefers either left or right eye input
what are orientation columns?
columns of cells with receptive fields that monitor similar retinal position
what are dorsal and ventral streams involved in?
- Ventral stream (inferotemporal): identity of objects/faces/scenes
- Dorsal stream (posterior parietal) : visual control of action/motion and spatial processing
list and explain some common types of perceptual dysfunction
- Apperceptive agnosia : recognise visual shapes
- Associative agnosia : recognise objects
- Achromatopsia : recognise a colour
- Prosopagnosia : recognise familiar faces
- Alexia : recognise texts
- Social emotional agnosia : interpret nonverbal social behaviour
Describe the case study of DF
DF : VISUAL FORM AGNOSIA
- Damage in inferotemporal cortex
- Very poor shape discrimination, but acuity and colour vision normal
- Task : distinguish square from rectangle (only 80% correct at 2:1 ratio)
- Poor at copying images but can accurately draw from memory (long term memory unaffected)
- Made recognition errors : from a photo of glasses, described the circle and crossbar but guessed bicycle
- Can orientate a stimulus e.g. can post a card manually but can’t match the slots orientation to a picture
- Damage to ventral stream
Describe the case study of RV
RV : OPTIC ATAXIA
- Damage to posterior parietal brain damage
- Problems with visually guided action, visual perception normal
- Problems inserting hand into orientated slot – would orientate hand wrong but COULD report orientation
- Does not grasp objects properly with thumb/ index finger
- Dorsal pathway impaired
what is area v4 involved in?
- Area v4 : involved in colour, orientation and spatial frequency
Shows tuning for shapes of immediate complexity
what is area v5 involved in?
perception of motion
what is contained within the inferotemporal cortex?
- Number of different gyri : (inferior, middle, superior temporal gyrus), fusiform gyrus
what areas aid in facial recognition?
- Areas found in ventral stream aid in face recognition
o Occipital face area, fusiform gyrus
o Cells have different tuning so will show differing activity to moving stimuli
what cells are involved in motion processing and where?
- Magnocellular ganglion cells involved in motion processing in dorsal pathway
- V5/MT important for motion processing
what is the function of the posterior parietal cortex
- Planned movements, spatial reasoning, attention
what is unilateral hemispatial neglect?
impairments in directing attention to parts of the visual field
what wavelength of light is important for vision?
- 400nm (blue) to 700nm (red)
what is achromatic and chromatic information?
- Achromatic info : important for fine detail, depth
- Chromatic info : important for colour
what are metamers?
physically different lights that appear identical
Can happen as there’s only 3 types of cone cells
what is the function of rods?
achromatic night vision
what is the function of cones and what are the three types?
daytime, achromatic and chromatic vision
Red cone : long wavelength sensitive
Green cone : middle-wavelength sensitive
Blue : short wavelength sensitive
what cells are mostly found in the periphery?
rods
what is the principle of univariance?
two different lights resulting in the same cone outputs
o Once absorbed a photon produces the same change in photoreceptor output whatever its wavelength
what do photoreceptors measure?
how many photons have been absorbed
what is protanopia?
: No L cones
Red/ greens not visible
what is deuteranopia?
: No M cones
Red/greens not visible
what is tritanopia?
: No S cones
Mostly grey/ purple visible
what does colour opponent theory state?
- Red and green, yellow and blue cannot be perceived at the same time : opponent colours
- Some ganglion cells are cone opponent
what does perceived colour depend on?
on temporal/ spatial factors (colour contrast/adaptation
- Colour and cognition are also connected (stroop effect)
what is functional localisation?
finding which components of the system are impaired
describe the case study of IES
- 75 year old male
- Bilateral posterior cerebral artery stroke involving ventral occipital lobes including left fusiform and lingual gyrus and right fusiform gyrus
- Also damage to left hippocampus and primary visual cortex
- Upper right quadrant visual field loss : quadrantanopia
- Visual object agnosia and prosopagnosia WITHOUT alexia
- VOA : recognising objects
- Prosopagnosia : face recognition
- Alexia : problems with reading
- Achromatopsia : colour blindness
- No language comprehension/ production problems
- No loss of semantic knowledge
- Named 32.8% of drawn images (BORB)
- 60% recognition of real objects (photorealistic)
- 3% success in famous face naming
- Perceptive integrative agnosia
- Poor ability to line length match and size match = deficit in low level feature perception
- Evidence of damage to lowlevel feature processing, perceptual integration, object constancy, accessing intact stored object knowledge
what is achromatopsia?
colour blindness
describe visual and semantic object naming errors. explain how these errors may arise in relation to brain damage
- Visual error : where response is visually similar to target
- May arise from damage to perceptual system BEFORE access to semantic info, e.g structures supporting colour, shape, low level feature processing, perceptual integration, object constancy
- Semantic : response is semantically related to target, but not visually similar
- May arise from damage to perceptual system AFTER access to semantic info, e.g structures supporting LTM representations of objects, semantic system
what is integrative agnosia and what damage may cause it?
- Difficulty with putting object parts together to see a whole spatial configuration
- Inferotemporal lesions (following PCA stroke)
name and briefly explain the forms of attention
- Active attention : top down, endogenous
• Controlled by intensions/goals/expectations
Passive attention : bottom-up, exogenous
• Controlled by external stimuli - Focused attention : selective
• Directed to one stimuli, amongst distracting stimuli
Divided attention : directed to more than one stimulus at a time - External attention : directed to selection of sensory info
Internal attention : directed to internally generated info - Overt attention : eyes directed to the object that is under focus of attention
Covert attention : focus of attention is independent of where we are looking
what is sound segregation and sound source of interest?
sound segregation : listener has to decide which sound to attend to
sound source of interest : once sound is detected attention must be directed/ kept towards source
what is the cocktail party situation?
when having a conversation at a party, background noise must be filtered out so attention can be focused on the conversation
what is the dichotic listening paradigm?
different auditory message is presented to each ear and must focus attention then repeat the words
- For the two messages to be heard there needs to be
• Clear physical difference, e.g location, pitch
explain Broadbent’s filter model and its critiques
- Series of channels which process different types of info
- Info passes through the channels and reaches a buffer store
- Filter then selects what info is to be further processed (based on properties e.g voice frequency, tone, pitch)
- Selected stimuli reach consciousness, unselected stimuli are rejected
CRITIQUES
o Inflexible
o Salient information can breakthrough into conscious processing
o Breakthrough errors : heard words from irrelevant message if they were probable in context
describe the attenuator model and give critiques
- Anna Treisman
1. Info reaches buffer store by going through channels
2. The filter attenuates instead of eliminating unattended material. All stimuli pass through the attenuator, but not all have the same level of importance
3. Some stimuli reach threshold for detection more easily, so goes to semantic processing and memory level - Expected stimuli have low detection thresholds (top-down influence)
- Unattended stimuli have high thresholds : get filtered out
o Some unattended stimuli have lower thresholds
Words with important meaning
• Words already processed in attended channel
• Words primed by the content from attended channel - doesn’t explain how semantic analysis works
give examples of early selection models
attenuator model
filter model
give examples of late selection models
deutsch and deutsch (1963)
norman (1968)
explain deutsch and deutsch’s model
- Deutsch & Deutsch’s (1963)
o All stimuli reach full processing level and get recognised
o Then selection is made based on semantic relevance for a reaction to be initiated
o Only this info reaches consciousness
explain norman’s model and give critiques
- Filter is as higher preconscious level
- Unattended stimuli can influence behaviour of attended stimuli
ADVANTAGES
No info is missed
DISADVANTAGES
Very demanding, a lot of brain power wasted
explain the perceptual load model and how the study was conducted
- Sees attention as a system with limited capacity
- Demanding tasks : lots of resources needed, so fewer resources will be left for other stimuli
- Combines early/late selection models
Early selection : demanding task, high load
Late selection : easy task, low load
TASK
o Number of letters was manipulated (low vs high load) and interference created using distractor letters
o Interference was greater in low load than high load
High load = no resources left, so distractor is not processed - More flexible and fluid
- Capacity is determined by task demands, characteristics, previous experiences
- Early selection : keeps assumption that perceptual capacity is limited
- Late selection : assumption that perceptual processing is automatic