index

Representations of space for visually-guided movements in parietal damaged patients.

Toronto, Canada

HSF Centre for Stroke Recovery, Sunnybrook & Women's College Health Sciences Centre. March 2006

Representations of space for visually-guided movements in parietal damaged patients.

San Francisco, California, USA

Smith-Kettlewell Eye Research Institute, January 2006

Eye-hand coordination in parietal patients.

Toronto, Canada

Centre for Vision Research, January 2004

Eye-hand coordination in parietal damaged patients.

Toronto, Canada

University of Toronto, Scarborough Campus, March 2003

The role of gaze direction in binocular eye hand alignment.

Lyon, France

Espace et Action, Inserm 534, January 2002

2006 Hand and target positions in multiple reference frames affect reach errors in unilateral parietal damaged patients.

Khan AZ, Pisella L, Blohm G, Rossetti Y, Crawford JD

Society for Neuroscience Abstracts, to be presented November 2006

2006 Initial hand position and movement direction affect reaching in a unilateral optic ataxia patient.

Khan AZ, Pisella L, Rossetti Y, Crawford JD

Vision Sciences Society Meeting 2006, 1016, Poster presentation

2005 Target and initial hand position affect gaze-centered reaching in a unilateral optic ataxia patient.

Khan AZ, Pisella L, Rossetti Y, Crawford JD

Society for Neuroscience Abstracts 2005, 287.20. Poster presentation

2005 Attention modulates saccade latency but not kinematics.

Khan AZ, Martinez- Trujillo J, Crawford JD

Vision Sciences Society Meeting 2005, 698. Poster presentation
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2004 The eye-hand coordination system synthesizes a common eye-centered internal representation of space for both arms.
Khan AZ, Ren L, Crawford, JD
Society for Neuroscience Abstracts 2004, 994.4. Poster presentation <>

2004 Contribution of proprioceptive feedback from the arm to the spatial updating of remembered target positions for saccades.

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Ren L, Khan AZ, Crawford JD

Society for Neuroscience Abstracts 2004. Poster presentation

2004 Attention and stimulus contrast modulate saccade latency but not kinematics.

Martinez-Trujillo JC , Khan AZ, Crawford JD

Society of Neuroscience Abstracts 2004. Slide presentation

2004 Errors in Optic Ataxia result from a damaged internal eye-centred representation.

Khan AZ, Pisella L, Crawford, JD, Rossetti Y

4th Forum of European Neurosciences. Poster presentation

2003 Errors in reaching in unilateral optic ataxia reflect a faulty eye-centred spatial representation.

Khan AZ, Pisella L, Crawford JD, Rossetti Y

Society of Neuroscience Abstracts 2003, 658.2. Slide presentation

2003 Eye-centered remapping in patients with bilateral parietal lobe lesions.

Khan AZ, Rossetti Y, Crawford JD

Vision Sciences Society Meeting 2003, SA 51. Poster presentation

2002 Updating of visual information across a delay in normals and optic ataxia patients.

Khan AZ, Crawford JD, Rossetti Y

Society of Neuroscience Abstracts 2002, 57.10. Poster presentation

2002 Eye-hand alignment in a pointing task varies with gaze direction.

Khan AZ, Crawford JD

3rd Forum for European Neurosciences 2002, 159.11. Poster presentation

2002 Gaze angle dependency of ocular dominance in a pointing task.

Khan AZ, Crawford JD

Annual Association for Research in Vision and Opthalmology Meeting 2002, 551. Poster presentation

2001 Coordinating one hand with two eyes: gaze-dependent reversal of ocular dominance in a pointing task.
Khan AZ, Crawford JD

2006 Ren L, Khan AZ, Blohm G, Henriques DYP, Sergio LE, Crawford JD

Proprioceptive guidance of saccades in eye-hand coordination.

Journal of Neurophysiology (in press)

2005 Khan AZ, Pisella L, Vighetto A, Cotton F, Luaute J, Boisson D, Salemme R, Crawford JD, Rossetti Y

Optic ataxia errors depend on remapped, not viewed, target location.

Nature Neuroscience, 8(4):418-420.

pdf

2005 Khan AZ, Pisella L, Rossetti Y, Vighetto A, Crawford JD

Impairment of gaze-centered updating of reach targets in bilateral parietal-occipital damaged patients.

Cerebral Cortex,15(10):1547-1560

pdf

2003 Khan AZ, Crawford, JD

Coordinating one hand with two eyes: Optimizing for field of view in a pointing task.

Vision Research, 43 (4): 409-417.

pdf

2003 Crawford JD, Henriques DYP, Medendorp MD, Khan AZ

Ocular kinematics and eye-hand coordination.

Strabismus, 11(1):33-47.

pdf

2001 Khan AZ, Crawford JD

Ocular dominance reverses as a function of horizontal gaze angle.
Vision Research, 41(14):1743-1748.

We interact with our environment by making reaching movements to objects we see. These movements involve a complex visual to motor transformation, from the visual information about the object's location relative to our line of sight (known as a gaze-centered representation) to the required arm command specified relative to the shoulder (i.e. in shoulder-centered coordinates). Because an object's location is encoded relative to gaze, this location must be updated when the line of sight shifts (with eye movements). In addition, the position of the hand has to be compared to the object's location at some point in the transformation process. By comparing the reaching behavior of patients with damage to the posterior parietal cortex to neurologically intact subjects, I investigated these updating and transformation processes as well as the role of the posterior parietal cortex in these mechanisms. My doctoral work first determined that the parietal cortex is necessary in spatial sensory-to-motor transformations but not for updating. Additionally, my thesis showed that this region seems to be involved predominately in transforming the locations of reach targets for rapid as opposed to delayed movements Finally, it demonstrated that the comparison between the current hand position and the target can also take place in shoulder-centered coordinates in addition to in a gaze-centered representation as has been previously suggested.