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Philippe
Chouinard, Ph.D. (McGill)
Post-Doctoral Fellow
Brain and Mind Institute and the Department of Psychology
The University of Western Ontario
London , Ontario , N6A 5C2
CANADA
I am a post-doctoral fellow working
with Dr. Melvyn Goodale at Western’s Brain and Mind Institute. My research is
concerned with the neural mechanisms underlying vision and action.
Specifically, my research examines the neural mechanisms that allow us to
identify and understand everyday objects (e.g. cell phones, cameras, utensils,
food, etc) and those that allow us to select and perform actions to make use of
these objects. It is also my long-term objective to examine how these processes
are affected in patients so that that my research can be translated into the
clinic. I use functional magnetic resonance imaging (fMRI) and transcranial
magnetic stimulation (TMS ) to study the brain. My research generally falls into one of the
following themes.
Functional
organization of the human visual and motor systems.
I use ‘fMRI-adaptation’ to examine the
functional specialization of different areas of the brain. Namely, what visual
and / or motor properties do brain areas process and not process. How does this
work? If a given brain area contains neurons that code for a particular
stimulus feature, or action, then the fMRI response is expected to be higher
during conditions in which that stimulus feature, or action, changes across
trials as compared to conditions in which that stimulus feature, or action, is
repeated. I am also interested in the application of TMS
to study the functional specificity of visual and / or motor areas by the
induction of “virtual lesions”. In other words, what effects happen and do not
happen when one “perturbs” neural activity in these different areas with
non-invasive brain stimulation. I am also interested in the retinotopic
organization of the visual cortex and how this organization is modulated by
perception.
Concepts,
actions, objects, and selection.
Concepts often dictate actions. Our leg
movements while driving a car are instructed by traffic lights. We hit the
brakes when we see a red light and we press on the accelerator when we see a
green light. Similarly, we need to know a few things about scissors in order to
select a functional hand configuration to ensure proper handling. In these
examples, there is nothing inherent about the stimuli that specify the actions
that we produce. Associations are learned and require an interaction between
brain structures that process their concepts and those that produce movements.
With advances in technology, our daily actions are becoming increasingly
dictated by learned associations between symbols and actions (e.g. the use of
computers, tablets, and smart phones). Because technology is evolving ever so
rapidly, it is imperative that we gain a better understanding of how the brain
allows us to identify objects and symbols and how it allows us to select
actions in response to these cues. This information could provide new ideas for
engineers on how to build better electronics and educators on how to improve
education with emerging technologies.
Research in
clinical populations.
The loss in the ability to
recognize objects visually, translate this information into actions, or produce
movements can impair our quality of life. This can come in the form of visual
agnosia (inability
to recognize objects visually),
apraxia (inability to select
actions to make use of
objects), or hemiparesis (failure
in conducting movements). The
examination of the intact
brain can provide
a better understanding of parallel neural
systems (i.e.
different ways
in which the brain can accomplish
a task) while
the examination of the damaged brain can
provide a better understanding of what is
and which is not
affected in patients. If it is
the case that parallel neural systems can be invoked
during a particular behavior and that
intact neural processing can compensate for deficts in damaged brain tissue
then my research could provide
important clues on how new compensatory strategies
could be developed for the rehabilitation of patients.
These strategies would
focus on training patients to
make use of intact neural
processes in order to compensate for
deficits caused by damage
to others.
Other interests
I am currently repeating some of my earlier fMRI
work on visual and semantic processing in people who are either “low” or “high”
on the Autism Spectrum Quotient (AQ) questionnaire (Baron-Cohen et al, Journal of Autism and Developmental
Disorders, 2001, 31, 5-18). The AQ questionnaire is designed
to measure the degree of sub-clinical autistic traits in the normal population.
In autism, there is a problem in seeing the forest for the trees. Visual
processing may differ depending on whether the observer is focused on the
overall (global) aspect of an image or its component (local) details. The
overall appearance of an image is preferentially processed in the normal
population whereas the opposite is observed in autism. Global processing is important
for building a repertoire of conceptual knowledge about the world. Take for
example the recognition of a fork and understanding its affordances. A fork
consists of a handle and tines. These components alone are insufficient for
proper identification and allowing a person to understand what action is
associated with a fork. If one were to consider only the fork’s handle then one
would not be able to differentiate it from other utensils. If one were to
consider only the fork’s tines then one would not be able to understand that it
is used to pick up food. Therefore, I would argue that “attention to details”
might profoundly affect one’s repertoire of conceptual knowledge and how one
processes concepts. Of course, all this is not to say that persons with autism
fail to attribute meaning to objects but rather that the underlying mechanisms
might be different. I am also carrying out behavioural
experiments on visual illusions and on the learning of conditional associations
in people who are either “low” or “high” on the AQ questionnaire.
In collaboration with Dr. Neil Duggal,
a neurosurgeon at the
Research papers:
Chouinard PA, Striemer CL, Ryu
WHA, Sperandio, I, Goodale MA, Nicolle
DA, Rotenberg B, and Duggal N (accepted) Retinotopic organization of the visual cortex before and
after decompression of the optic chiasm in a patient with pituitary macroadenoma. J Neurosurg.
Sperandio I, Chouinard PA, and Goodale MA
(2012) Retinotopic activity in V1 reflects the
perceived not the retinal size of an after-image. Nat Neurosci 15:540-542. [Pubmed Link]
Chouinard PA, and Goodale MA (2012) FMRI-adaptation to
highly-rendered color photographs of animals and manipulable artifacts during a
classification task. Neuroimage 59: 2941-2951. [Pubmed Link]
Striemer CL, Chouinard PA, and Goodale MA (2011)
Programs for action in superior parietal cortex: A triple-pulse
Chouinard PA, and Goodale MA (2010) Category-specific
neural processing for naming pictures of animals and naming pictures of tools: an
Chouinard PA, Whitwell RL, and Goodale MA (2009) The lateral-occipital
and the inferior-frontal cortex play different roles during the naming of
visually-presented objects. Hum Brain Mapp. 30:3851-3864. [Pubmed Link]
Chouinard PA, and Goodale MA (2009) FMRI adaptation during
performance of learned arbitrary visuomotor
conditional associations. Neuroimage 48: 696–706. [Pubmed Link]
Gofton TE, Chouinard PA, Young GB, Bihari F, Nicolle MW, Lee DH,
Sharpe MD, Yen Y-F, Takahashi AM, and Mirsattari SM
(2009) Functional
Chouinard PA,
Large M-E, Chang EC, and Goodale MA (2009) Dissociable neural mechanisms for
determining the perceived heaviness of objects and the predicted weight of
objects during lifting: an fMRI investigation of the size-weight illusion. Neuroimage 44: 200-212. [Pubmed Link]
Chouinard PA, Morrissey BF, Köhler S, and Goodale MA (2008)
Repetition suppression in occipital-temporal visual areas is modulated by
physical rather than semantic features of objects. Neuroimage
41: 130-144. [Pubmed Link]
Chouinard
PA, Leonard G, and Paus T (2006) Changes in effective connectivity
of the motor cortex in stroke patients after rehabilitative therapy. Exp Neurol 201:
375-387. [Pubmed Link]
Chouinard PA, Leonard G, and Paus T (2005) The
role of the primary motor and dorsal premotor cortices in the anticipation of
forces during object lifting. J Neurosci 25:2277-84. [Pubmed Link]
Barrett JA, Della-Maggiore V, Chouinard PA, and Paus T (2004)
Mechanisms of action underlying the effect of repetitive transcranial magnetic
stimulation on mood: the role of a frontocingulate
circuit. Neuropsychopharmacology 29:1172-89. [Pubmed
Link]
Chouinard PA, Van Der Werf YD, Leonard G, and Paus T (2003) Modulating neural
networks with transcranial magnetic stimulation applied over the dorsal
premotor and primary motor cortices. J Neurophysiol 90:1071-1083. [Pubmed Link]
Review
papers:
Chouinard PA, and Paus T (2010). What have we learned from
‘perturbing’ the human cortical motor system with transcranial magnetic
stimulation? Front Hum Neurosci 4:173. doi:
10.3389/fnhum.2010.00173. [Pubmed Link]
Chouinard PA, and Paus T (2006) The primary motor and
premotor areas of the human cerebral cortex. Neuroscientist 12:143-152. [Pubmed Link]
Commentaries:
Chouinard PA, and Goodale MA (2007) Functional reorganization in the adult brain.
Neuron 54: 352-353. [Pubmed Link]
Chouinard PA (2006) Different roles of PMv and PMd during object lifting. J Neurosci
26:6397-98. [Pubmed Link]
Last revised: