Distributed neural networks of tactile working memory

Abstract

Microelectrode recordings of cortical activity in primates performing working memory tasks reveal some cortical neurons exhibiting sustained or graded persistent elevations in firing rate during the period in which sensory information is actively maintained in short-term memory. These neurons are called “memory cells”. Imaging and transcranial magnetic stimulation studies indicate that memory cells may arise from distributed cortical networks. Depending on the sensory modality of the memorandum in working memory tasks, neurons exhibiting memory-correlated patterns of firing have been detected in different association cortices including prefrontal cortex, and primary sensory cortices as well. Here we elaborate on neurophysiological experiments that lead to our understanding of the neuromechanisms of working memory, and mainly discuss findings on widely distributed cortical networks involved in tactile working memory.

Finger representations in primary somatosensory cortex are modulated by a vibrotactile working memory task

“…This suggests that sensory brain regions not only process sensory stimuli, but also retain and manipulate sensory information in the absence of any sensory input, also known as 'sensory recruitment' models. According to these models, vibrotactile information is processed in S1, relayed to S2, which possesses a reciprocal connection with S1 and disseminates information via insular projections to frontal and parietal regions (Wang et al, 2013). This account is in line with our parametric mapping results.…”

Noradrenergic dysfunction in Alzheimer's disease

“…Clonidine and guanfacine can improve working memory in aged monkeys with documented memory impairment (Arnsten and Goldman-Rakic, 1985 , 1987 ; Arnsten et al, 1988 ). It is known that working memory is mainly localized to the prefrontal cortex (Wang et al, 2013c ) whereas spatial and fear memory involve the hippocampus (Bird and Burgess, 2008 ). The difference in clonidine's effects on these different cognitive paradigms is likely due to diverse functions of α 2 receptors in regulating neurotransmission in different brain regions.…”

The Processing of Somatosensory Information Shifts from an Early Parallel into a Serial Processing Mode: A Combined fMRI/MEG Study

“…It was previously demonstrated that the memory trace of a tactile stimulus is held not only in the prefrontal cortex and the posterior parietal cortex (Romo et al, 1999; Kaas et al, 2013) but also in the SI (Zhou and Fuster, 1996; Harris et al, 2001; Pasternak and Greenlee, 2005; Kaas et al, 2013; Wang et al, 2013). The presence of memory cells in the SI agrees well with the theory that memory is stored in the same cortical system that participates in the processing of these sensory information (Squire and Zola-Morgan, 1991).…”

“…The presence of memory cells in the SI agrees well with the theory that memory is stored in the same cortical system that participates in the processing of these sensory information (Squire and Zola-Morgan, 1991). The SI therefore has dual functions: to encode sensory stimuli and to store this information for short amounts of time (Zhou and Fuster, 1996; Pasternak and Greenlee, 2005; Wang et al, 2013). It was further shown that the SI retains tactile memory traces for at least as long as the tactile stimulus was applied (Harris et al, 2002).…”