Topics in Spatial Cognition from Barbara Hidalgo-Sotelo

Transcription

1 Topics in Spatial Cognition from Barbara Hidalgo-Sotelo Spatial frames of reference Structure of space Arriving at a unified sense of space is complex Three cases: (1)Hemispatial Neglect (2)Visual form agnosia (3)Simultagnosia & Balint s syndrome

2 Visuospatial Neglect: When spatial attention goes wrong

3 Diagnosis of Spatial Neglect

4 Diagnosis of Spatial Neglect

5 Diagnosis of Spatial Neglect

6 Diagnosis of Spatial Neglect

7 Diagnosis of Spatial Neglect In order of sensitivity: Star Cancellation Indented Paragraph INSTRUCTION Cross out all of the small stars Line bisection Line crossing

8 Diagnosis of Spatial Neglect

9 Hemi-Spatial Neglect or Hemi-Anopia? Line Bisection tasks Neglect patients transect line ~ Ipsi-lesional side Hemianopics transect in ~ Contra-lesional side Visual scan paths Neglect patients: more abnormal scans & fewer glances into neglected field (compared w/ hemianopics) Visual acuity tests Neglect patients will omit one side; Is the ones side of the world missing? Clumsy? Weird behavior? Ask the family (patient will deny)

10 Where does Left side of space live in the brain?

11 Spatial Reference Frames Egocentric: Spatial coding with respect to view-centered fame of reference (e.g. Head, Hand, etc ) Allocentric: ( Other -centered) Objects relative to each other Object-centered Note the significance of Left

12 Spatial Reference Frames: Differences between copying and drawing from memory: (mental image had complete representational access that the percept did not)

13 An note about Attention & Frame of Reference Preserved figure-ground segregation in visual neglect: Copy the display shown Copy the RIGHT side of the white figure on the Left Copy the LEFT side of the white figure on the Right

14 Oddities of Spatial Neglect

15 Neuropsychological structure of space Representation of different spatial domains: Personal space Body surface Peripersonal space Arm s reach Extrapersonal space Out of reach Does the human brain represent these spaces differently? Clues from Neglect patients Studies of Normals

16 Neuropsychological structure of space Neglect patients: show double dissocations FAR line bisection: show left neglect & NEAR line bisection: normal Normals: Distinct neural substrates Action in NEAR space Action in FAR space Weiss (2000). Neural consequences of acting in near vs far space

17 Visual Object Agnosia a.k.a. Visual Form Agnosia

18 Visual Object Agnosia Behavioral and neuroimaging evidence for a contribution of color and texture information to scene classification (Steeves et al 2004)

19 Another oddity of selective attention: Simultagnosia Inability to recognize 2 or more things at the same time Dorsal Simultagnosia Ventral Simultagnosia

20 Bilateral Parietal Damage: The case of Balint s Syndrome Balint s syndrome: 3 perceptual dysfunctions Simultagnosia Optic ataxia Oculomotor apraxia

21 Balint s Syndrome in a 10 yr old male Structural MRI: Bilateral posterior parietal damage

22 Balint s Syndrome in a 10 yr old male Ophthalmology assessment normal (!) Intact visual fields, Normal Acuity Normal stereopsis Abnormal eye movements (voluntary vs invol.) Could identify events: Trouble finding a pencil on a cluttered desk

23 Rehabilitation in Balint s Syndrome Take an adaptive approach (use what you got) Feed in information in form that can be assimilated Organization (physically) Habitual scanning of environment Dictating improved schoolwork Use extra-visual modalities to locate objects Simply identifying the problem has been shown to begin improvement of the condition

24 Topics in Spatial Cognition Spatial frames of reference Egocentric Allocentric Structure of space Personal, Peripersonal, Extrapersonal Arriving at a unified sense of space is complex: Dysfunctions of Attentional selection are as handicapping as Dysfunctions in the sensory sytems