Vivien Casagrande
Last active: 2/12/2015


The overall goal of this research is to understand how the visual thalamus and cortex interact to construct our perceptual world. The first project explores the unconventional proposal that the primary sensory information received by the visual cortex from the visual thalamus [e.g., the lateral geniculate nucleus (LGN)] is not purely visual but rather visual information, primed by inputs from other sensory modalities. In this project, we hypothesize that the primate brain achieves fast and accurate decision-making in part due to its ability to focus, right from the beginning, on relevant aspects of inputs from all sense organs without appreciating all the details presented by each sense organ. Our specific hypothesis is that auditory and visual information are combined in a task dependent manner in the visual thalamus before this message is processed in cortex. In a second project, we test the hypothesis that all thalamic nuclei contain some cell groups that act as drivers (send the main message) and some that act as modulators for multiple cortical areas, thus mediating the generation of an array of diverse cortical functions. The thalamus is not simply a passive relay to cortex. Instead, just as primary visual cortex (V1) depends on LGN, the secondary visual area (V2) and the middle temporal visual area (MT) depend on a combination of dedicated pathways through the thalamus (e.g., pulvinar) and direct feedforward connections from V1.This arrangement allows new properties to emerge at both the thalamic and cortical levels through dynamic loops. A third project focuses on communication between cells in different areas of visual cortex and examines how visual messages are coded and transmitted from lower to higher visual areas and what the role of feedback is in this process. We use a variety of electrophysiological, anatomical, and imaging approaches to address these questions including single unit and multielectrode recording in both anesthetized and awake behaving primates, light, electron microscopic and confocal examination of cells and circuits, optical imaging of intrinsic signals and pharmacological manipulation. Our laboratory also has had a long standing interest in the evolution of the visual system. Therefore, we continue to use a comparative approach to examine for similarities and differences in the organization of the visual system in a variety of primate species.


The following timeline graph is generated from all co-authored publications.

Featured publications are shown below:

  1. Neural mechanisms of coarse-to-fine discrimination in the visual cortex. Purushothaman G, Chen X, Yampolsky D, Casagrande VA (2014) J Neurophysiol 112(11): 2822-33
    › Primary publication · 25210162 (PubMed) · PMC4254879 (PubMed Central)
  2. A Generalized ideal observer model for decoding sensory neural responses. Purushothaman G, Casagrande VA (2013) Front Psychol : 617
    › Primary publication · 24137135 (PubMed) · PMC3786228 (PubMed Central)
  3. Retinotopic maps in the pulvinar of bush baby (Otolemur garnettii). Li K, Patel J, Purushothaman G, Marion RT, Casagrande VA (2013) J Comp Neurol 521(15): 3432-50
    › Primary publication · 23640865 (PubMed) · PMC3775912 (PubMed Central)
  4. Morphological and neurochemical comparisons between pulvinar and V1 projections to V2. Marion R, Li K, Purushothaman G, Jiang Y, Casagrande VA (2013) J Comp Neurol 521(4): 813-32
    › Primary publication · 22826174 (PubMed) · PMC3513524 (PubMed Central)
  5. Intrinsic signal optical imaging evidence for dorsal V3 in the prosimian galago (Otolemur garnettii). Fan RH, Baldwin MK, Jermakowicz WJ, Casagrande VA, Kaas JH, Roe AW (2012) J Comp Neurol 520(18): 4254-74
    › Primary publication · 22628051 (PubMed) · PMC3593310 (PubMed Central)
  6. Gating and control of primary visual cortex by pulvinar. Purushothaman G, Marion R, Li K, Casagrande VA (2012) Nat Neurosci 15(6): 905-12
    › Primary publication · 22561455 (PubMed) · PMC3430824 (PubMed Central)
  7. Functional organization of temporal frequency selectivity in primate visual cortex. Khaytin I, Chen X, Royal DW, Ruiz O, Jermakowicz WJ, Siegel RM, Casagrande VA (2008) Cereb Cortex 18(8): 1828-42
    › Primary publication · 18056699 (PubMed) · PMC2790394 (PubMed Central)
  8. Neural networks a century after Cajal. Jermakowicz WJ, Casagrande VA (2007) Brain Res Rev 55(2): 264-84
    › Primary publication · 17692925 (PubMed) · PMC2101763 (PubMed Central)
  9. How do functional maps in primary visual cortex vary with eccentricity? Xu X, Anderson TJ, Casagrande VA (2007) J Comp Neurol 501(5): 741-55
    › Primary publication · 17299757 (PubMed)
  10. The morphology of the koniocellular axon pathway in the macaque monkey. Casagrande VA, Yazar F, Jones KD, Ding Y (2007) Cereb Cortex 17(10): 2334-45
    › Primary publication · 17215477 (PubMed)
  11. Unequal representation of cardinal vs. oblique orientations in the middle temporal visual area. Xu X, Collins CE, Khaytin I, Kaas JH, Casagrande VA (2006) Proc Natl Acad Sci U S A 103(46): 17490-5
    › Primary publication · 17088527 (PubMed) · PMC1859956 (PubMed Central)
  12. Low-threshold Ca2+-associated bursts are rare events in the LGN of the awake behaving monkey. Ruiz O, Royal D, Sáry G, Chen X, Schall JD, Casagrande VA (2006) J Neurophysiol 95(6): 3401-13
    › Primary publication · 16510773 (PubMed)
  13. On the impact of attention and motor planning on the lateral geniculate nucleus. Casagrande VA, Sáry G, Royal D, Ruiz O (2005) Prog Brain Res : 11-29
    › Primary publication · 16226573 (PubMed)
  14. Correlates of motor planning and postsaccadic fixation in the macaque monkey lateral geniculate nucleus. Royal DW, Sáry G, Schall JD, Casagrande VA (2006) Exp Brain Res 168(1-2): 62-75
    › Primary publication · 16151777 (PubMed)
  15. Optical imaging of visually evoked responses in the middle temporal area after deactivation of primary visual cortex in adult primates. Collins CE, Xu X, Khaytin I, Kaskan PM, Casagrande VA, Kaas JH (2005) Proc Natl Acad Sci U S A 102(15): 5594-9
    › Primary publication · 15809438 (PubMed) · PMC556248 (PubMed Central)
  16. Functional organization of visual cortex in the owl monkey. Xu X, Bosking W, Sáry G, Stefansic J, Shima D, Casagrande V (2004) J Neurosci 24(28): 6237-47
    › Primary publication · 15254078 (PubMed) · PMC6729553 (PubMed Central)
  17. Optical imaging of visually evoked responses in prosimian primates reveals conserved features of the middle temporal visual area. Xu X, Collins CE, Kaskan PM, Khaytin I, Kaas JH, Casagrande VA (2004) Proc Natl Acad Sci U S A 101(8): 2566-71
    › Primary publication · 14983049 (PubMed) · PMC356990 (PubMed Central)
  18. The role of L1 in axon pathfinding and fasciculation. Wiencken-Barger AE, Mavity-Hudson J, Bartsch U, Schachner M, Casagrande VA (2004) Cereb Cortex 14(2): 121-31
    › Primary publication · 14704209 (PubMed)
  19. Modeling receptive-field structure of koniocellular, magnocellular, and parvocellular LGN cells in the owl monkey (Aotus trivigatus). Xu X, Bonds AB, Casagrande VA (2002) Vis Neurosci 19(6): 703-11
    › Primary publication · 12688666 (PubMed)
  20. Chronic and acute analysis of optic nerve sheath fenestration with the free electron laser in monkeys. Joos KM, Mawn LA, Shen JH, Casagrande VA (2003) Lasers Surg Med 32(1): 32-41
    › Primary publication · 12516068 (PubMed)