RT Journal Article
SR Electronic
T1 Latency and Selectivity of Single Neurons Indicate Hierarchical Processing in the Human Medial Temporal Lobe
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 8865
OP 8872
DO 10.1523/JNEUROSCI.1640-08.2008
VO 28
IS 36
A1 Florian Mormann
A1 Simon Kornblith
A1 Rodrigo Quian Quiroga
A1 Alexander Kraskov
A1 Moran Cerf
A1 Itzhak Fried
A1 Christof Koch
YR 2008
UL http://www.jneurosci.org/content/28/36/8865.abstract
AB Neurons in the temporal lobe of both monkeys and humans show selective responses to classes of visual stimuli and even to specific individuals. In this study, we investigate the latency and selectivity of visually responsive neurons recorded from microelectrodes in the parahippocampal cortex, entorhinal cortex, hippocampus, and amygdala of human subjects during a visual object presentation task. During 96 experimental sessions in 35 subjects, we recorded from a total of 3278 neurons. Of these units, 398 responded selectively to one or more of the presented stimuli. Mean response latencies were substantially larger than those reported in monkeys. We observed a highly significant correlation between the latency and the selectivity of these neurons: the longer the latency the greater the selectivity. Particularly, parahippocampal neurons were found to respond significantly earlier and less selectively than those in the other three regions. Regional analysis showed significant correlations between latency and selectivity within the parahippocampal cortex, entorhinal cortex, and hippocampus, but not within the amygdala. The later and more selective responses tended to be generated by cells with sparse baseline firing rates and vice versa. Our results provide direct evidence for hierarchical processing of sensory information at the interface between the visual pathway and the limbic system, by which increasingly refined and specific representations of stimulus identity are generated over time along the anatomic pathways of the medial temporal lobe.