A University of Tokyo research group has found that when monkeys successfully recall visual objects from memory, neuronal circuits spanning cortical layers in the lower subarea of the temporal cortex are activated by an inter-area top-down signal from a higher subarea of the temporal cortex.
Previous studies have demonstrated that neurons in the inferior temporal cortex contribute to the long-term memory of visual objects. However, it was still unknown whether and how neurons in the subarea of the inferior temporal cortex interacted with neurons in other subareas during memory retrieval, because previous studies typically recorded single neuron activity from a single electrode.
The research group of then Project Lecturer Masaki Takeda and then Professor Yasushi Miyashita at the Graduate School of Medicine recorded neuronal signals simultaneously from areas 36 and TE of the inferior temporal cortex by using multi-contact linear electrodes. The researchers found that inter-laminar signal processing in area TE was activated by way of inter-area top-down signals from area 36 when monkeys successfully retrieved a target visual object from long-term memory.
The technique of simultaneous recording and analysis of inter-area and inter-layer signals will enhance our understanding of the operation of brain-wide neuronal circuits for memory retrieval and will promote research into the neuronal mechanisms underlying disorders of visual memory.
The results of this research were published in the online edition of the American scientific journal Neuron on 24 April 2015 (Japan time).
Source: University of Tokyo