| |
Abstract:
Ventral prefrontal cortex is known to be involved in the
ability to maintain a behavioral set and to make appropriate
switches between behavioral sets. Human patient and animal studies
have demonstrated that lesions to ventral prefrontal cortex often
result in perseverative responding. Using functional MRI, we
compared the brain activation elicited during well-learned and
novel stimulus-response mappings with the prediction that novel
behavioral sets would preferentially activate ventral rather than
dorsal prefrontal regions and that children may recruit more dorsal
prefrontal cortex based on our previous studies. Nine right handed
adults (mean age=24.5 years) and nine right handed children (mean
age=8.8 years) were scanned while performing the stimulus-response
compatibility task. Echo planar images (TR = 6000, TE = 40, 128 X
64) were acquired in twenty-six 5 mm contiguous coronal slice
locations. Preliminary results based on analyses of variance with a
contiguity threshold of 3 pixels and p < 0.05 showed that
incompatible mappings relative to compatible mappings resulted in
right ventral prefrontal (BA 47, 11) and bilateral parietal (BA 1,
40) activation for adults, and right thalamus, right caudate and
bilateral superior and middle frontal gyri (BA 8, 9) activation for
children. Results will be discussed in terms of the prolonged
development of prefrontal cortex and the parallel development of
efficiency in maintaining information.
|
