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 Rats Reflect 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

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

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 Collins Kellie 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 AnteriorBodyPosterior Volume Control:largerNo difference b/n grps Taxi grp: larger HemisphereRight side was larger (for control) insignificant Interaction 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