Activation of midbrain structures by associative novelty and the formation of explicit memory in humans.
Recent evidence suggests a close functional relationship between memory formation in the hippocampus and dopaminergic neuromodulation originating in the ventral tegmental area and medial substantia nigra of the midbrain. Here we report midbrain activation in two functional MRI studies of visual memory in healthy young adults. In the first study, participants distinguished between familiar and novel configurations of pairs of items which had been studied together by either learning the location or the identity of the items. In the second study, participants studied words by either rating the words' pleasantness or counting syllables. The ventral tegmental area and medial substantia nigra showed increased activation by associative novelty (first study) and subsequent free recall performance (second study). In both studies, this activation accompanied hippocampal activation, but was unaffected by the study task. Thus midbrain regions seem to participate selectively in hippocampus-dependent processes of associative novelty and explicit memory formation, but appear to be unaffected by other task-relevant aspects.
Schott
Björn H
BH
Department of Neurology II, Otto von Guericke University, Magdeburg 39120, Germany.
Sellner
Daniela B
DB
Lauer
Corinna-J
CJ
Habib
Reza
R
Frey
Julietta U
JU
Guderian
Sebastian
S
Heinze
Hans-Jochen
HJ
Düzel
Emrah
E
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005145:Face; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008636:Mesencephalon / Q000098:blood supply / Q000502:physiology*; D021641:Recognition, Psychology / Q000502:physiology; D012016:Reference Values; D013378:Substantia Nigra / Q000502:physiology; D017557:Ventral Tegmental Area / Q000502:physiology