spatial cognition xxx. spatial cognition is concerned with the acquisition, organization,...
Post on 20-Dec-2015
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SPATIAL COGNITION
XXX
Spatial Cognition is concerned with the acquisition, organization,
utilization, and revision of knowledge about spatial
environments. These capabilities enable humans to manage basic and high-level cognitive tasks in
everyday life.
SPATIAL COGNITION A Couple Aspects of Spatial Cognition:
I. Visuospatial Perception including "Spatial Awareness"
a. Spatial Coordinate Systems or Spatial Reference Frames.
b. Spatial Feature Integration II. Spatial Navigation
a. spatial cognitive map and route finding.
b. path integration
Neuroanatomy of Spatial Cogntion??? A. Ventral Visual Stream leading downward
into the temporal lobe (inferotemporal cortex - IT).
What is it? B. Dorsal Visual Stream leading upward or
forward into the Parietal Cortex (area PG).Where is it?
Dorsal and Ventral Streams:Parallel systems with substantial interconnectivity.
What’s the Parietal Lobe Doing?
• Attention
• Neglect
• Simultanagnosia (in Balint’s syndrome)
• Optic Ataxia
• Spatial representation
• Apraxia
• Visuomotor integration
• Hemisphere diffs
Hypothesis: Parietal Cortex neurons construct space by combining multi-sensory modalities with motor signals.
• VIP: Perioral space– visual + tactile responses– Tactile RFs are centered around the mouth– V+T units have similar movement direction tuning – Visual responses can be eye- or head-centered– Some visual responses are tuned to movement
of an object toward a particular portion of the face, independent of gaze
– Some visual responses are sensitive only to stimuli that are near the face (< 5cm)
– Connected to F4, which controls head/mouth movements
* Head mov’t / “grasping” with mouth
• AIP: Object Shape– Visual, motor, and visuo+motor responses– Visual units are object shape and orientation
sensitive– Motor responses are hand-movement sensitive– Deactivation causes grasping deficits– Connected to area F5, which is involved in
grasping
*Grasping with hand
• MIP: Immediate Extrapersonal Space– Visual, somato, and bimodal units– Pure somato units have RFs on the hand– Bimodal units activate strongly during reaching– Some pure visual units show stronger
responses when a target is within reaching distance
– Bimodal RFs are located near each other (tactile RF on the hand = visual RF near hand)
• Visual RF moves with hand!• Visual RF expands when monkey uses a tool for
reaching!
*Reaching with arm
"Spatial Awareness" - Posterior Parietal Cortex LIP (lateral intraparietal)- Neurons respond to the onset of visual stimuli. Visual responses are enhanced by requiring that the monkey attends to the stimulus. Prolonged responses occur when the monkey must remember the location of in which the stimulus occurred. Neurons contribute to the updating of the internal image. "Eye-centered spatial representation"
Parietal Cortex Neurons in RatsReflect Route traversals
Behavioral Correlates of PC Neurons
For parietal neurons, high correlations were observed between outbound and inbound unit activity vectors aligned according to behavioral sequence (first versus second traces = rbeh), but were negative when aligned according to the sequence of spatial positions encountered (first versus third traces = rspace). The opposite pattern was observed for the CA1 hippocampal neuron.
Recording Cells in the Hipocampus
(Does it have a spatial map?)
Hippocampal Cell Layers
Hippocampal Cell Layers
Electrodes Finding Cells
Computer Monitoring of Activity After Amplification
Hippocampal Pyramidal Cell Complex Spike
Place cells are stable when the entire environment rotates as long as the animal is not disoriented during the rotation.
Place Field on Circular Track
Place Field Expansion
Place Field Expansion
Spatial “Grid Cells” in Entorhinal Cortex
Tessellation of a city map by squares provides information about position, distance and direction, allowing specific places to be easily located. b, Hafting et al.1 find that as a rat explores an experimental enclosure, the discharge rate of a neuron in the dorsocaudal medial entorhinal cortex increases at regular intervals corresponding to the vertices of a triangular grid. c, Integration of information from several grid components (that is, from the outputs of several neurons) can increase the spatial resolution of the environment. Three triangular grids are represented here, with red displaced and blue rotated relative to a neuron grid shown in black. GR
Grid Cells:
GRID CELLS DON’T SCALE
GRID Cells Align to External Cues, but persist when the cues are
removed.
Grids persist in the dark!
GRID Cells Code similarly in different
environments
Navigational-related structural change in the Hippocampi of Taxi
Drivers
Presented by Jill Campbell, Monica Chattha, James CollinsKellie Gray and Kristen Lai Fatt
Maguire, Gadian, Johnsrude, Good, Ashburner, Frackowiak & Frith.
Background
• The hippocampus is KNOWN to be involved in spatial navigation & cognition in animals
– ↑ in relative hippocampal volume in small mammals and birds that engage in behaviour requiring spatial memory (i.e. food storing)
– ↑ in hippocampal volumes specifically during seasons when demand for spatial ability greatest – species specific
tendency for animal hippocampi to undergo structural changes in response to behaviour requiring spatial memory
Hippocampal refresher
Background
• The hippocampus is strongly BELIEVED to play a similar role in humans
– structural brain differences b/w distinct groups of subjects documented (ex. Males vs. females, musicians vs. non-musicians)
– lesion work and functional neuroimaging have confirmed the involvement of human hippocampus in spatial memory and navigation but not its precise role
differences in brain morphology predetermined OR due to plastic change in response to environmental stimulation??
Hypothesis
In healthy humans, the hippocampus will be the most likely brain region to show physical changes associated with extensive navigation
Analysis of volumes for 3 sections of the hippocampus
Anterior Body Posterior
Volume Control:larger No difference b/n grps
Taxi grp: larger
Hemisphere Right side was larger (for control)
Right side was larger (for control)
insignificant
Interaction none none none
Changes with Navigation Experience
•The more time spent being a taxi driver, the smaller the anterior hippocampus
• The more time spent being a taxi driver, the larger the right posterior hippocampus
Implications
• Plasticity of hippocampus results from spatial experience
• Extensive spatial experience causes growth of posterior hippocampus
• Trade off between size of Anterior and Posterior hippocampus• Posterior HC = storage of previously learned
spatial information in humans• Anterior HC = encoding of new spatial environment
in humans
If this is true then Taxi Drivers should be slower at learning spatial orientation of completely new & unique environments