Separating Storage from Retrieval Dysfunction of Temporal Memory in Parkinson’s Disease Malapani, Deweer & Gibbon (2002) Tiffany Wang

 Symptoms: o Bradykinesia - slowing in motor o Bradyphrenia - slowing in cognition o 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 intervals o 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 experiment o ON or OFF medication (L-dopa) during 2 experimental days  Controls  ON-ON: no distortion in timing  OFF-OFF: migration in both sessions 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 slowed o Interference/coupling occurs during retrieval  Suggests neuroanatomy of these functions separate o Storage: rely on simple, excitatory corticostriatal neuro path o Retrieval: involvement of inhibitory striato-pallidal circuit Discussion

 Strengths o Effectively tested for storage separate from retrieval processes  Limitations o All participants diagnosed with PD o No specification of gender/age o Lack of brain imaging Strengths & Limitations

 Test whether dysfunction in storing and retrieving temporal memories rely on distinct neural networks o Using brain imaging o 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), Questions?