Recent　studies　have　demonstrated　that　mentally　rotating　the　hands　involves　participants　engaging　in　motor　imagery　processing.　However,　far　less　is　known　about　the　possible　neurophysiological　basis　of　such　processing.　To　contribute　to　a　better　understanding　of　hand　mental　rotation　processing,　event-related　spectral　perturbation　(ERSP)　methods　were　applied　to　electroencephalography　(EEG)　data　collected　from　participants　mentally　rotating　their　hands.　Time-frequency　analyses　revealed　that　alpha-band　power　suppression　was　larger　over　central-parietal　regions.　This　is　in　accordance　with　motor　imagery　findings　suggesting　that　the　motor　regions　may　be　involved　in　processing　or　detection　of　kinaesthetic　information.　Furthermore,　the　presence　of　a　significant　negative　correlation　between　reaction　times　(RTs)　and　alpha-band　power　suppression　over　central　regions　is　illustrated.　These　findings　are　consistent　with　the　neural　efficiency　hypothesis,　which　proposes　the　non-use　of　many　brain　regions　irrelevant　for　the　task　performance　as　well　as　the　more　focused　use　of　specific　task-related　regions　in　individuals　with　better　performance.　These　results　indicate　that　ERSP　provides　some　independent　insights　into　the　mental　rotation　process　and　further　confirms　that　parietal　and　motor　cortices　are　involved　in　mental　rotation.　(C)　2013　Elsevier　Ireland　Ltd.　All　rights　reserved.