Neural activity in mediodorsal nucleus of thalamus in rats performing a working memory task

Abstract

Theneuralcircuitconsistingofmediodorsalnucleus(MDN)ofthalamusandprefrontalcortex(PFC)hasbeenimplicatedinworkingmemory.InordertoinvestigatewhetherandhowtherodentMDNprocessesworkingmemory-relatedsignals,werecordedactivityofsingleneuronsfromtheMDNinratsperformingadelayedspatialalternationtask.TheMDNconveyedsignificantneuralsignalsfortheanimal’spreviouslychosengoal(retrospectiveinformation)intheearlydelayperiod,butthesignalsdeterioratedgraduallyovertimesothattheybecameweaktowardtheendofthedelayperiod.Neuralsignalsfortheanimal’supcominggoalchoice(prospectiveinformation)wereevenweakerthanthoseforthepreviouslychosengoal.TheseresultsareincontrasttothefindinginmonkeysthatbothMDNandPFCpersistentlymaintaintask-relatedneuralsignalsthroughoutdelayperiod.OurresultsdonotsupportsustainedMDN-PFCinteractionsasageneralmechanismformediatingworkingmemoryacrossdifferentbehavioraltasksand/oranimalspecies.