DIFFERENTIAL RECOVERY OF VOLITIONAL MOTOR FUNCTION, LATERALIZED COGNITIVE FUNCTION, DOPAMINE AGONIST-INDUCED ROTATION AND DOPAMINERGIC PARAMETERS IN MONKEYS MADE HEMI-PARKINSONIAN BY INTRACAROTID MPTP INFUSION
Js. Schneider et al., DIFFERENTIAL RECOVERY OF VOLITIONAL MOTOR FUNCTION, LATERALIZED COGNITIVE FUNCTION, DOPAMINE AGONIST-INDUCED ROTATION AND DOPAMINERGIC PARAMETERS IN MONKEYS MADE HEMI-PARKINSONIAN BY INTRACAROTID MPTP INFUSION, Brain research, 672(1-2), 1995, pp. 112-127
There is still controversy regarding the fequency and extent of sponta
neous functional recovery in primate models of parkinsonism, perhaps i
n part stemming from the variety of ways in which recovery has been as
sessed. The present study examined functional recovery in monkeys made
unilaterally parkinsonian by intracarotid infusion of MPTP. Monkeys w
ere evaluated prior to lesioning and for at least 1 year after lesioni
ng on a battery of tests including a rating of spontaneous behaviors,
a learned reaction time/movement time task, tests of lateralized negle
ct or inattention (i.e. lateralized reward retrieval task, extinction
with double simultaneous stimulation, and response to a target moving
from one hemispace to the other), and rotational asymmetry in response
to a dopamine agonist, Some animals also received 6-[F-18]Fluoro-L-Do
pa (F-DOPA) positron emission tomography (PET) scans before MPTP, when
symptomatic, and when showing signs of functional recovery. These ani
mals were sacrificed for post mortem neurochemical assessment followin
g the last PET scan. Results showed that estimates of functional recov
ery in hemi-parkinsonian monkeys may depend upon the behavioral assay
used. Even in behavioral tasks that were sensitive to recovery effects
, the degree of functional recovery shown by an animal on one such tas
k did not predict recovery on another. This may in part be due to the
inherent difficulty in designing behavioral tests to assess basal gang
lia functioning, when there is no consensus concerning which aspects o
f behavior the normal basal ganglia actually control. The results also
suggest that the relationship of post-mortem striatal dopamine levels
or in vivo estimates of pre-synaptic dopaminergic function to functio
nal recovery are also tenuous. The hemi-parkinsonian monkey is a valua
ble but complex behavioral model and care needs to be taken in assessi
ng functional impairment and functional recovery in such animals.