Separating Storage from Retrieval Dysfunction of Temporal
Memory in Parkinson’s DiseaseMalapani, Deweer & Gibbon (2002)
Tiffany Wang
Symptoms:o Bradykinesia - slowing in motoro Bradyphrenia - slowing in cognitiono Poor time estimation
Associated brain areas:o Dysfunction of basal ganglia & brain nuclei
Dopamine deficiency in substantia nigra projecting to striatum
Parkinson’s Disease
Temporal memory – the ability to compensate for the passage of time during locomotory behaviour
“Migration effect”o Dependent on two learned time intervalso Overestimate the shorter of two intervals, and
underestimate the longer of the two
Definitions
Test whether it is storing or retrieval dysfunction responsible for the distortion of time interval with dopamine deficiency.
Research Question
Using encode-decode experimentoON or OFF medication (L-dopa) during
2 experimental days
ControlsON-ON: no distortion in timingOFF-OFF: migration in both sessions
Predictions
Predictions
Participants 36 Parkinson’s Disease diagnosed patients
Encode-decode experiment Short time interval (6sec) Long time interval(17sec)
Method
Day 1 storage session 20 fixed-time trials 30 peak trials with feedback 10 peak trials without feedback
Day 2 Retrieval session 60 peak trials without feedback
Method
Results
- Migration in all OFF state
- Overestimation for both target intervals in the OFF – ON state
Dissociation between deficits in storage and retrieval temporal memory processes
Dopamine deficiency leads to:o Process of time interval storing in memory slowedo Interference/coupling occurs during retrieval
Suggests neuroanatomy of these functions separateo Storage: rely on simple, excitatory corticostriatal
neuro patho Retrieval: involvement of inhibitory striato-pallidal
circuit
Discussion
Strengthso Effectively tested for storage separate from
retrieval processes
Limitationso All participants diagnosed with PDo No specification of gender/ageo Lack of brain imaging
Strengths & Limitations
Test whether dysfunction in storing and retrieving temporal memories rely on distinct neural networkso Using brain imagingo Compare PD subjects with normal subjects
Future Directions
Malapani, C., Deweer, B., & Gibbon, J. (2002). Separating Storage from Retrieval Dysfunction of Temporal Memory in Parkinson's Disease. Journal of Cognitive Neuroscience, 14(2), 311 - 322.
Questions?