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Separating Storage from Retrieval Dysfunction of Temporal Memory in Parkinson’s Disease. Malapani , Deweer & Gibbon (2002). Tiffany Wang. Parkinson’s Disease. Symptoms : Bradykinesia - slowing in motor Bradyphrenia - slowing in cognition Poor time estimation Associated brain areas :
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Separating Storage from Retrieval Dysfunction of Temporal Memory in Parkinson’s Disease Malapani, Deweer & Gibbon (2002) Tiffany Wang
Parkinson’s Disease • Symptoms: • Bradykinesia- slowing in motor • Bradyphrenia- slowing in cognition • Poor time estimation • Associated brain areas: • Dysfunction of basal ganglia & brain nuclei • Dopamine deficiency in substantianigra projecting to striatum
Definitions • Temporal memory – the ability to compensate for the passage of time during locomotory behaviour • “Migration effect” • Dependent on two learned time intervals • Overestimate the shorter of two intervals, and underestimate the longer of the two
Research Question Test whether it is storing or retrieval dysfunction responsible for the distortion of time interval with dopamine deficiency.
Predictions • Using encode-decode experiment • ON or OFF medication (L-dopa) during 2 experimental days • Controls • ON-ON: no distortion in timing • OFF-OFF: migration in both sessions
Method • 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
Results • Migration in all OFF state • Overestimation for both target intervals in the OFF – ON state
Discussion • Dissociation between deficits in storage and retrieval temporal memory processes • Dopamine deficiency leads to: • Process of time interval storing in memory slowed • Interference/coupling occurs during retrieval • Suggests neuroanatomy of these functions separate • Storage: rely on simple, excitatory corticostriatalneuropath • Retrieval: involvement of inhibitory striato-pallidalcircuit
Strengths & Limitations • Strengths • Effectively tested for storage separate from retrieval processes • Limitations • All participants diagnosed with PD • No specification of gender/age • Lack of brain imaging
Future Directions • Test whether dysfunction in storing and retrieving temporal memories rely on distinct neural networks • Using brain imaging • Compare PD subjects with normal subjects
Questions? 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.