The neural correlates of learning by observation

As Bandura (1977) affirmed, new behaviours are often learned
observationally through modelling: from observing others we can form an idea of
how new behaviours are performed, and on later occasions this coded information
serves as a guide for action.
Therefore, observational learning improves human adaptability and enables
individuals to acquire a vast store of knowledge without incurring the costs of
discovering and testing this knowledge themselves (Boyd & Richerson 1985,
Cavalli-Sforza & Feldman 1981). Interestingly, social learning is not merely a
mechanism by means of which children acquire culture, but may also have
pervasive influence throughout adulthood. For example, driving a car safely in
the streets necessitates a precise knowledge of the meaning of several abstract
road signs, and this meaning can be learned via distinct mechanisms. It can be
learned in a risky way by trial and errors, or more easily by observation of
others* driving behaviour. In daily life the *rules* that guide our behaviour
are very often the association between a visual stimulus present in the
environment and a particular action (arbitrary visuo-motor association, see
Introduction).
Several studies investigate the neural substrates of rule learning by trial and
error. In general, the neural network that underlies the acquisition by trial
and error and execution of arbitrary visuomotor associations includes parts of
prefrontal (PFC) and premotor (PM) cortices, the hippocampal system (HS) and
the basal ganglia (BG) (see Murray et al., 2000 for review).
In particular, a number of positron emission tomography (PET) and functional
magnetic resonance imaging (fMRI) studies have sought to identify the neural
networks involved in arbitrary sensorimotor learning by trial and errors in
humans (for reviews, see Brasted and Wise, 2005). Regional cerebral blood flow
have been shown to vary during conditional visuomotor learning in the frontal
and parietal networks (Dieber et al., 1997) and in the prefrontal-basal ganglia
pathways (Toni and Passingham, 1999). Toni et al. (2001) found that the
amplitude of the blood oxygenation level-dependent (BOLD) signal measured in
the temporo-prefrontal areas changed significantly during learning. Eliassen et
al. (2003) confirmed that the BOLD responses vary from initial learning to
rehearsal and differentiate for errors and correct responses; in addition, the
BOLD signal in some areas changed very rapidly during learning between the
first correct and subsequent correct trials. More recently, Law et al. (2005)
identified the behavioral correlates of a class of changes in BOLD response and
found that signals in the medial temporal lobe (MTL) as well as in the
cingulate cortex and frontal lobe correlate either positively or negatively
with the probability of correct response.
Surprisingly, despite its outstanding scientific interest, the neural bases of
visuomotor observational learning have not been studied and remain obscure.
Following results obtained in a precedent fMRI study (Monfardini et al, in
prep.), our goal is to explore the possibility that specific neural structures
contribute to generate an internal representation of an abstract rule linking
environmental information (visual stimuli) with observation of another*s
action.

The main objective of this research is to disentangle the neural mechanisms
involved in two important forms of learning: trial and error individual
learning vs. learning by observation.

Subjects will be asked to learn arbitrary visuo-motor associations between a
visual stimulus (linear segments combined to form white shapes on a black
background) and a motor response (joystick movements in four directions). The
subjects will learn a number of associations either by trial and error (T&E
;condition 1) or by observation of a video showing an actor executing the task
(LeO; condition 2). In the T&E condition, visual-feedback (a green happy or
red sad smiley-like face) will help the subject to find the correct visuo-motor
association between the stimulus and a joystick movement in a given direction.
In the LeO condition, the subject will learn the visuomotor association by
watching a short video showing an actor performing the visuo-motor task. The
visual feedback given to the actor will help the subject to learn the task by
observation. After each Leo condition, the subject will be tested to assess his
knowledge of the visuomotor rule he had to learn by observation. Two basic
conditions will control for both motor execution and visual observation.
Details of the study and experimental design can be found in the Study Design
section of this proposal.

Subjects will be exposed to a magnetic field of 3Tesla and rapidly alternating
magnetic gradients and radio frequency fields. This field strength is used
routinely in fMRI and MRI research. So far, no side effects have been
described. On rare occasions, a peripheral nerve in the abdomen is stimulated
by changing magnetic gradients. This causes an itching feeling, but is not
harmful. Volunteers with MRI incompatible implants (such as pace makers, pins,
or aneurysm clips) will be excluded from this study. If a subject shows a
claustrophobic reaction inside the MRI scanner, the study will be terminated
and the subject will be excluded from further research. Because the MRI machine
generates loud noise, volunteers will wear ear-plugs.

There are no benefits for the subjects for participation in the study.