What is Where and How to Get There The Neurocognition of Space Albert Postma Psychological Laboratory, Utrecht firstname.lastname@example.org http://www.fss.uu.nl/psn/pionier/
Examples of tasks involving mental spatial processes - Does the trunk of elephant reach to the ground if the animal is standing in a normal (horizontal) position? - Imagine the capital letter ‘d’. Turn it 90° to the left. Place the letter ‘j’ below it in the centre. What do you see? - Lay down your pencil… - Attend the entrance door of the classroom D D J
( Spatial Cognition:= the collection of mental abilities which involve the processing of spatial features of our environment or of complex objects (ranging from perception, attention, motor action to memory). Spatial features include distance (depth), relative and absolute position, orientation (direction)
Why Study Spatial Cognition? - Essential for many daily activities (ecological importance) - Several recent interesting neurocognitive findings - Space is the common attribute of all our senses - Other cognitive acts may essentially be ‘spatially motivated’ (e.g. language evolution) - High extent of specialization of neural circuits for spatial tasks
The anatomical separation of visual cortical processing within a dorsal and ventral stream is well established. What about the functions that are subserved by these two visual streams? Ungeleider & Mishkin (1982) Based their distinction on stimulus attributes Ventral stream: What is the stimulus Dorsal stream: Where is the stimulus
Dorsal and ventral stream Ungeleider & Mishkin (1982) Experimental evidence that supports this functional distinction: Lesion studies with monkeys Two tasks: Object discrimination and spatial discrimination.
Dorsal and ventral stream Ungeleider & Mishkin (1982) Lesion studies with monkeys Object discrimination Delayed non-matching to sample Monkeys with a bilateral lesion of the inferotemporal lobe are impaired on this task.
Dorsal and ventral stream Ungeleider & Mishkin (1982) Lesion studies with monkeys Spatial discrimination Landmark discrimination Choose the foodwell closer to the ‘landmark’. Monkeys with bilateral posterior parietal lesions are impaired on this task.
Dorsal and ventral stream The conclusion that the landmark task showed that monkeys with parietal lesions were impaired in spatial discrimination was criticized by Milner & Goodale (1995) for several reasons. Instead they proposed a different division of labour based on what the visual information is used for, rather than the stimulus characteristics. Ventral: Visual perception Dorsal: Visual guidance of goal-directed action
Dorsal and ventral stream Patient studies: Optic ataxia: – Disorder of spatial perception or visually guided action? – Jakobson et al. (1991), Jeannerod et al. (1994) report a patient who was impaired in adjusting their grip aperture to the size of the object.
Dorsal and ventral stream Patient studies: Patient DF: – Visual form agnosia – Impaired recognition of form orientation, location – However, she can use visual information to guide her actions
Ilussion distortion larger in judgment than in pointing However, with delayed pointing the illusion impact increases
Involvement of the ventral stream in visuomotor behaviour
Milner & Goodale (1995) Perceptual identification requires different visual information than goal directed action REFERENCE Allocentric Egocentric
Hoe werkt dit voor de haptische waarneming? Zuidhoek, S., Kappers, A.M.L., van der Lubbe, R.H.J. and Postma, A. (submitted to Experimental Brain Research). Delay improves performance on a haptic spatial matching task.
Result: deviation in delay trials is smaller than in immediate trials
immediate 10 second delay Na een pauze wordt de staaf minder aan de orientatie van de hand gecodeerd maar meer in ‘cognitieve’ termen (visualisatie strategie) => Kunnen blinden dit ook? ref test
Remembering what was where: How is spatial information stored in memory? The hippocampal formation seems crucial (extending the ventral stream), receiving both egocentric and allocentric projections
Connections to and from the hippocampus Hippocampus brings multimodal, highly processed information together and consolidates it into memory
Place and direction cells are found in the hippocampal formation, which code location, direction, and speed and distance (theta rhythm). These functional properties form the basis for cognitive maps which support a) wayfinding b) goal identification and calculation of trajectories c) predicting interactions between agents and objects d) other cognitive abilities (temporal, linguistic etc..)
What about lateralisation? => Smith & Milner (1981, 1985, 1995) In humans the hippocampus also supports spatial memory (Kessels, De Haan, Kappelle & Postma, Brain Reseerch Reviews, 2001)
Most studies suggest right sided lateralisation for spatial memory. However, this depends on the specific conditions
Apparently, there exists specific neural circuitries dedicated to spatial memory - dorsal & ventral stream provide egocentric and allocentric reference, resp. - left & right hemisphere provide categorical and coordinate spatial metrics, resp. - hippocampus supports cognitive map for (allocentric) spatial memory => at a functional level, it might be hypothesized that spatial memory is relatively autonomous, working in an automatic fashion
Hasher & Zacks (1979) Automatic Processes: -nonintentional -unaware -no load on central resources or attention -difficult to suppress Effortfull Processes: -intentional, voluntary -conscious -capacity limited -flexible Features coded automatically in memory: frequency and order of occurrence, location
Criteria for Automaticity No effects of: a) Intent to Learn b) Age c) Practice and Feedback d) Individual Differences/ Intelligence e) Concurrent Processing Loads
Conclusions on automaticity of spatial memory appear to depend upon the type of task used. Both implicit (automatic) and explicit (effortfull) influences may drive spatial memory performance Future research: to what extent do different neurological groups suffer specific implicit or explicit spatial memory impairments?
Implicit and Explicit Spatial Memory in Korsakoff Patients Knowing where things are in our environment is so critically important that we may retain and use this information (implicit memory) without conciously remembering it (explicit memory) Korsakoff patients suffer huge problems in spatial memory (e.g. binding of attributes and context memory seems particularly affected) Question: does their implicit spatial memory survive?
Inclusion condition: probability target response = C + (1-C)U C = explicit component; U = implicit component Exclusion condition: probability target response = (1 - C)U
Atractive features: - ecological valid task - connects to the everyday life problems of these patients - sheds light on the interaction between implicit and explicit memory and their neural bases Problem: - working with clinical groups: do Korsakoffs understand the instructions? Caldwell & Masson, 2001
Can a CKI student do some really pioneering work in Space? Yes!! Burgess, 2002
Arguably, spatial cognition is one of an organism’s most important abilities Surprisingly, our knowledge of the neurocognition of space is relatively sparse Future decades might show an increase in neurocognitive research in this domain http://www.fss.uu.nl/psn/pionier/