Brain as prediction machine
—> expectations shape perception
—> brain is proactive —> coarse to fine processing
feedback loops allow us to make hypotheses —> anticipate the consequences of actions and formulate expectations
—> brain is not reactive
—> low and high complexity of prediction
Hierarchical Organisation of visual processing
processed information gets increasingly complex
retina
optic nerve
optic chiasma
lateral geniculate nucleus
magnocellular layers —> black
koniocellular layers —> blue /yellow
parvocellular layers —> red/green
primary visual cortex
two streams from visual cortex
Dorsal stream —> parietal lobe -> where/how
ventral stream —> temportal lobe -> what
processed information gets more and more complex
feedback connections in the brain
40-60 ms: v1
-80 ms: v2/v4
-100 inferotemporal cortex —> object recognition
-120 ms to PFC and V1
-140 ms inferotemporal cortex to v2/v4
150+ ms pfc to inferotemporal cortext
Why is brain prediction machine
information is often
incomplete
noisy
ambiguous
to predict better/earlier/faster means evolutionary advantage
to build internal models to plan actions
Expectation shapes vision how?
Life priors
contextual priors
expectations
assumptions and expectations based on an individual's accumulated experiences over their lifetime.
examples
light usually shines from above
how reflections look
textures -> familiarity with textures —> we expect them to look a certain way
Contextual priors
Contextual priors are more narrowly focused on specific contexts or environments
shading
relative sizes in scenes
bistability
how we see the obect depends on what we expect/have seen before
cueing! When being told letter E —> recognizing E
prior experience
what is a prediction?
incomplete information
taking statistical regulatrities of the world and letting them fill the missing information
Coarse to fine Hypothesis
two visual pathways
magnocellular (black) —> dorsal stream —> where?
parvocellular (red and green) —> ventral stream —> what?
Magnocellular pathway
low spatial frequency
motion
fast signal
where?
—> from v1 to pfc
—> coarse information that is faster —> proactive guessing
parvocellular pathway
what?
high spatial frequency
colors
slow signal
Whole process
Input
two separate pathways simultaneously
lsf object —> possible objects
lsf scene image —> possible context
brain region
MPFC / OFC
RetroSplenial Complex; ParaHippocampal Cortex
combination in inferotemporal cortex
what are the three main components in prediction
Associations based on experiences are foundation for
Analogies which trigger specific
Predictions relevant to the current context
Associations
based on past experiences
brain regions
medial temporal lobe
hippocampus
parahippocampal cortex
analogies
map new inputs to existing representations to look for similarities
association-based prediction
not recognition!
predictions
analogies trigger predictions relevant to current context
what influences the complexity of prediction
spatial frequency
context information
—> simultaneous bottom up and top down processes due to
incomplete data
contextual information
prior knowledge
Last changed2 months ago