module 4 Flashcards
EEG
electroencephalogram - measures activity in response to a stimuli at a particular time
structural mri
anatomy of the brain - used to detect structural anomalies
fmri
gives information about activity in the brain - uses oxygenated blood flow as an indirect measure of neural activity
magnet detects changes in oxygenated blood - ratio of oxygenated and deoxygenated blood flow in regions of the brain is measured during a task and measurements are used to create a spatial image of brain activity
right lateral occipitotemporal cortex
area of the brain that becomes active when we view images of body parts
parahippocampal place area
area in temporal lobe that is active when we think about spatial layouts
supplementary motor area
area of the brain that is active when we perform of imagine movement
functional specialization and fmri for communication
knowledge of brain specialization has been used to communicate with people in vegetative states through measuring brain activity in fmri - patients are asked to respond yes/no to questions by thinking about things that either activate the parahippocampal place area or the supplementary motor area
strengths and weaknesses of fmri
strengths: good spatial resolution, lots of replication
weaknesses: bad temporal resolution - hard to determine the timing of brain activity, indirect correlational measure, picks up a lot of signals/very noisy
brain stimulation
noninvasive method of changing brain activity that can inhibit or increase activity
transcranial magnetic stimulation
magnetic stimulation used to induce temporary change in brain activity - studies suggest that tms may improve memory- experiment with face word memory tests
pros and cons of tms
pro: good for testing causality
con: not entirely clear how it works - hard to localize effects
exteroceptive sensations
any form of sensation that results from stimuli located outside the body detected by sensory organs
interoceptive sensations
sensations from inside our body - studies have shown that dancers have increased interoceptive accuracy - were able to estimate heart rate more accurately than non dancers
proprioception
sense of where our limbs are in space
nociception
sense of pain due to body damage
equilibrioception
sense of balance
synaesthesia
neurological condition in which one sense automatically triggers the experience of another sense - genetic component - 40% of patients have family members with the condition
due to cross wiring between processing areas in the brain? (hypothesis)
grapheme color synesthesia
a person sees colors with certain letters or numbers
artists with synesthesia
artists are 8 times more likely to have synesthesia than non artists - cross talk between sensory areas in the brain increases the ability to think creatively and in metaphors
is pain a sensation or a perception?
perception
mcgurk effect
you hear what you see - baaa to faaa illusion - integration of sensory information/dominance of visual input
early vs late visual processing
early visual processing (sensation): eyes and optic nerve
late visual processing (perception): visual cortex (occipital lobe)
early visual processing
- light waves projected onto the retina
- photoreceptors convert light into electrical activity
- electrical signal goes to bipolar and then ganglion cells
- signal exits through optic nerve to the brain
information compression
millions of photoreceptors in each retina converge onto 100x fewer ganglion cells, meaning input from the eyes to the brain is compressed
distribution of photoreceptors in the retina
cones are more concentrated in the fovea, whereas rods are mostly in the periphery
blind spot
no photoreceptors where optic nerve leaves the eye - we usually don’t notice because the brain fills it in and also the left and right visual fields can compensate for each other’s blindspot
late visual processing
signals leave the eyes and cross over contralaterally to the thalamus on the opposite side - from there information gets sent to the primary visual cortexes and onto the visual association areas
primary visual cortex
specialized regions that process particular visual attributes or features - edges, angles, color, light
visual association areas
interpret visual information and assign meaning
pathways to visual association areas
what (ventral) pathway - occipital to temporal lobe
- shape, size, visual details
where (dorsal) pathway - occipital to parietal lobe
- location, space, movement information
dorsal and ventral pathways as ‘action’ and ‘perception’?
ventral damage with intact dorsal stream
impaired performance on visual object recognition or matching tasks
dorsal damage with intact ventral stream
impaired performance on visually guided action
what happens to visual input in the cortex
it gets broken down, processed separately and then combined to form a perception of an entity - reality we perceive is a construction of the brain
bottom up processing
external environment influence perception - sensory organs
top down processing
knowledge (expectations context and goals) influences perception - higher areas of the brain - prefrontal cortex/higher visual processing
constructivist theory of perception
we use what we know and current context to predict how to perceive sensory data - top down processes - what we expect to see
ex. subjective experience of pain - partly determined by expectations- shock experiment
examples of how context affects visual perception
- ames room - people look taller in a trapezoid shaped room, because we expect rooms to be rectangle shaped, so assume its just the person thats huge
-letters in context - we can read words in sentences even when the letters are mixed up
- color in context - colors look different (lighter, darker, etc) depending on what they are next to
correspondence
process by which the brain guesses the location of objects in space
bi stable stimuli
illusions that can be perceived multiple ways
what is the first structure of the eye that light passes through
cornea then iris /pupil (hoel in iris)
perspective projection
objects that are farther away produce a smaller image than those that are close by
lateral geniculate nucleus
part of the thalamus that receives 90% of visual information from the retina
