Non-invasive detection of neuronal population activity in human hippocampus.
Medial temporal brain structures and hippocampus are associated with memory encoding and activate during registration and transfer of information within cortico-hippocampal circuits. Hippocampal dysfunction may cause learning and memory deficits as well as epileptogenesis. We monitored neuronal population activity of the human hippocampal formation with a whole-head magnetoencephalographic array. Attention-dependent hippocampal responses were elicited by auditory oddball stimuli. The most prominent responses emerged 200-500 ms after attended oddballs in good agreement with earlier intracranial recordings. Some activation of hippocampal source areas was seen at 60-100 ms. This completely non-invasive method permits access to cortico-hippocampal neural networks on the millisecond time scale during normal and abnormal brain activation and thus provides a new tool for evaluation of cognitive processes and pathological conditions involving hippocampal formation.
Tesche
C D
CD
Low Temperature Laboratory, Helsinki University of Technology, Espoo, Finland. tesche@neuro.hut.fi
Karhu
J
J
Tissari
S O
SO
D000161:Acoustic Stimulation; D000328:Adult; D001288:Attention; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D003071:Cognition; D007839:Functional Laterality; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D013997:Time Factors