L2- Sensation, Integration, & Simple Navigation Flashcards
Why do we need to combine different sensory sources?
-Object identification
-Fundamental evolutionary alarm systems
-Visual-auditory spatial localisation
-Reliable control of locomotion
-Retain coherence of the world
Describe Ernst & Banks’ (2002) visual haptic integration study
-3 conditions:
stereo visual display only; haptic inspection only; both sources
-task- judge object size with various ‘noise’ level
-better performance in visual with no noise, but affected most by noise
-best performance in combined condition, decreased less as noise increased
-flexible weighting of sources to enhance performance
Where does information for proprioception come from?
Stretch receptors- muscle & joint ligaments
Vestibular system (inner ear)- semicircular canals (head rotation) & otolith organs (translations)
What do single unit recordings of monkey’s VIP region suggest?
-measure cell response & strength of response
-cell fired most when stimulus on left middle part of screen
-visual receptive field of this VIP neutron is fixed with respect to head position, irrespective of eye position
-neuron doesn’t encode fixed retinal location, but location relative to the head
-also responds more to stimulus moving towards mouth
How do VIP cells match reference frames across sensory modalities?
Neurons respond to visual and somatosensory info in roughly matching places and sizes
-e.g. top left in visual field and left eyebrow
How do body-centred LIP cells encode head turns?
E.g. Maximal firing when head faces left of body whether monkey actively moved head or body passively rotated
-requires integration of vestibular signals, muscles and tendons, and vision
Summarise sensory integration
-integration occurs within and across modalities, but strongest within
-parietal regions implicated in integrating info in difference coordinate systems
-each parietal area specialised for different reference frames
What navigation strategy do ants use?
Path Integration (PI):
-Picks up info every time it stops and changes direction
-Continually generates home vector
-Home vector contains direction and distance
How do ants determine direction within PI?
-Internal compass
-Continuously measures E-Vector patterns in the sky (electric vectors of light)
-Dorsal rim area of eye specialised for detection on polarised light direction
How do ants determine distance within PI?
-Retinal image flow/ optic flow
-Kinaesthethic info may also be helpful (e.g. number of steps)
What are the problems with Path Integration? How could this be accounted for
-Cannot be interrupted during movement without errors
-Susceptible to cumulative errors of navigation (small errors build up)
-Allocentric landmark info could provide a solution to these by providing a point of reference
Describe Wehner, Michal, & Antonsen’s study of ant navigation with landmarks?
-Ants picked up after returning to nest and displaced
-Able to navigate back- must be dure to landmarks as no path to integrate
-Then tested ants from other areas- local ants better at navigation
Do ants have a ‘cognitive map’? Describe
-They have a limited 2D snapshot of visual scenes
-Fixed in retinal coordinates
-Doesnt rotate with body
-Matching retinal images requires same body orientation as acquisition
-No transfer between or within eyes
How do ants combine PI and landmark info?
-Combination more accurate
-If ant has no home vector, uses landmark
-If vector established, this drives behaviour
What strategy do bees use to navigate?
Combination of PI and landmark information
