... Mellon University 2 University of Toronto at Scarborough 3 University of Minnesota 4 National Institute of Health 5 Children's Hospital of Pittsburgh of UPMC.
The topography of early & higher-order visual cortex in patients with hemispherectomy/lobectomy Marlene 1 Carnegie
1 Behrmann ,
Tina
1 Liu ,
Adrian
Kendrick
3 Kay ,
Mark
1 Vida ,
John
1 Pyles ,
Xilin
4 Zhang ,
Within- vs. Between-hemisphere/patient
Summary
• Within-subject: How does resection in one hemisphere affect retinotopy/category selectivity within/cross-hemisphere? • Between-subject: How does resection in a particular area of the brain affect retinotopy/category selectivity in general?
• Surgery to resect tissue in cases of intractable epilepsy • Opportunity to examine plasticity and cortical reorganization
Patient 1 (left anterior temporal lobectomy)
The BIG Question How does the removal of cortex (anterior vs. posterior, ventral vs. dorsal, LH vs. RH) alter the dynamics of visual processing?
Christina
5 Patterson
Mellon University 2 University of Toronto at Scarborough 3 University of Minnesota 4 National Institute of Health 5 Children's Hospital of Pittsburgh of UPMC
Hemispherectomy/lobectomy
early visual cortex: retinotopic organization
2 Nestor ,
patient profile
• • • • • •
Patient 2 (right posterior hemispherectomy)
• no evidence of remapping in the structurally intact LH Patient 2 • consistent with visual perimetry results (hemianopsia) • from atypical face selectivity in the remaining hemisphere to more typical selectivity maps (from session 1 to 3)
• Age 7, Male • Posterior temporal lobectomy + occipital lobectomy (Right Hemisphere) • Normal IQ and comprehension • No motor deficit • Homonymous hemianopsia • Normal low-level vision • Normal face perception: CFMT-C
Age 15, Male Anterior temporal lobectomy (Left Hemisphere) Normal IQ and comprehension Full visual fields Normal low-level vision Prosopagnosic: CFMT (upright faces: 31 out of 72, inverted faces: 34 out of 72)
higher-order visual cortex: category selectivity
typical maps in early visual areas in the remaining hemisphere (LH)
typical bilateral maps in early visual areas
• typical meridian mapping in early visual cortex (V1-V3) Patient 1 • pFR slope may reflect consequences of the cortical resection • typical face- & object-selectivity in the remaining visual cortex in both hemispheres
Take-home Message Cortical reorganization: • The developing ventral visual pathway:
meridian mapping: Wandell, Winawer, & Kay (2014)
• from atypical/diminished selectivity for common visual categories to more typical selectivity maps (1-2.5 yr post-surgery)
Grill-Spector & Weiner (2014)
Horizontal – Vertical
Methods
RVF – LVF
UVP – LoVF
atypical left ventral pRF: long-term changes following resected lATL
meridian mapping:
Left Hemisphere
RVF – LVF: - no reorganization of the missing LVF
Horizontal – Vertical: - Typical mapping in LH
UVP – LoVF: - Typical mapping in LH
atypical face- & object-selectivity in the remaining hemisphere (LH)
Right Hemisphere
Dorsal maps
• from session 1 to 3: extensive selectivity in the rATL, emerging lATL, lFFA and lSTS, no apparent lOFA z = -20
early visual cortex
Patient z = -18
pRF:
Ventral maps
session 1 (age 7)
session 2 (age 7.5)
Absence of cortical reorganization: • The structurally intact early visual cortex may not reorganize to represent the ipsilateral visual field.
References
z = -21
Brewer, A. A., & Barton, B. (2012). Visual field map organization in human visual cortex. In S. Molotchnikoff (Ed.), Visual Cortex – Current Status and Perspectives. Grill-Spector, K., & Weiner, KS. (2014). The functional architecture of the ventral temporal cortex and its role in categorization. Nat Rev Neurosci. Wandell, BA., & Winawer, J. (2015). Computational neuroimaging and population receptive fields. TiCS. Wandell, BA, Winawer, J. & Kay, KN. (2014). Computational modeling of responses in human visual cortex. In A.W. Toga (Ed.), Brain Mapping: An Encyclopedic Reference.
Faces – Houses
pRF:
• resection in anterior regions of the visual hierarchy may have feedback effects that adversely impact ventral/dorsal visual field maps.
Age-matched control z = -20
z = -18
• Feedback from higher-order areas to visual field maps
session 3 (age 8)
• from session 1 to session 3: relatively stable object selectivity in the left LOC Patient
typical face- & object-selectivity in the remaining visual cortex z = -5
Brewer & Barton (2012)
z = -6
Wandell & Winawer (2015)
functional localizer:
higher-order visual cortex
z = -3
Age-matched control
Objects – Scrambled
CLOSE Faces – Houses
Houses – Faces
Objects – Scrambled
Words – Faces
session 1 (age 7)
session 2 (age 7.5)
session 3 (age 8)
z = -6
z = -5
Grant support: This research was supported by a grant from the National Institutes of Health (EY023067) to MB.
