Ventrolateral prefrontal cortex and tactile memory disambiguation in the human brain

Abstract

Tactile sensory information is first channeled from the primary somatosensory cortex on the postcentral gyrus to the parietal opercular region (i.e., the secondary somatosensory cortex) and the rostral inferior parietal lobule and, from there, to the prefrontal cortex, with which bidirectional connections exist. Although we know that tactile memory signals can be found in the prefrontal cortex, the contribution of the different prefrontal areas to tactile memory remains unclear. The present functional MRI study shows that a specific part of the prefrontal cortex in the human brain, namely the midventrolateral prefrontal region (cytoarchitectonic areas 47/12 and 45), is involved in active controlled retrieval processing necessary for the disambiguation of vibrotactile information in short-term memory. Furthermore, we demonstrate that this particular part of the prefrontal cortex interacts functionally with the secondary somatosensory areas in the parietal operculum and the rostral inferior parietal lobule during controlled processing for the retrieval of specific tactile information.functional MRI ͉ retrieval ͉ working memory A natomical, physiological, and lesion/behavior studies show that tactile sensory information necessary to interpret texture, shape, and vibration is channeled from the primary somatosensory cortex (SI) on the postcentral gyrus to the frontoparietal opercular region [i.e., the secondary somatosensory cortex (SII)] and the rostral inferior parietal lobule (i.e., area PF of Economo or area 40 of Brodmann) for further processing (1-8). The secondary somatosensory areas in the frontoparietal opercular region and the rostral inferior parietal lobule, unlike SI, are bidirectionally connected with the

Ventrolateral and dorsomedial frontal cortex lesions impair mnemonic context retrieval

“…However, the experiment was designed to test the hypothesis that the VLPFC is critical for the disambiguation of mnemonic traces when the relations between stimuli and their contexts are unstable [20][21][22][23]. Patients with lesions to the VLPFC were predicted to be selectively impaired on the unstable context retrieval condition which assesses active controlled retrieval.…”

“…This study tested the above predictions by examining the performance of patients with damage to the frontal cortex on three memory retrieval conditions, in which the level of ambiguity between stimulus items and their contexts was manipulated by varying the probability with which a stimulus (word) and a context (background) appeared in relation to one another [20][21][22][23]. Performance of patients with lesions to the frontal cortex was compared with that of patients with temporal lobe lesions that had involved the hippocampus and parahippocampal cortex, as well as healthy control subjects.…”

“…Thus, the engagement of the prefrontal cortex in context/source retrieval is not obligatory and the ventrolateral prefrontal cortex (VLPFC) becomes necessary as ambiguity in item-to-context relations increases. This specific hypothesis was tested with functional neuroimaging, and evidence was provided for selective increases in activity in the VLPFC when human subjects were retrieving specific stimulus features that had occurred in association with multiple contexts [20][21][22][23], but direct evidence of the critical involvement of an area in such retrieval, which can only be provided by lesion studies, is not available.…”

Selective memory retrieval of auditory what and auditory where involves the ventrolateral prefrontal cortex

“…Most studies investigating the role of the prefrontal cortex in the auditory domain have focused on verbal phonological and semantic memory (23)(24)(25). The aim of the present study was to examine the hypothesis that the midventrolateral prefrontal cortex is involved in the active controlled retrieval of nonverbal auditory information from memory, in a manner analogous to its previously demonstrated role in the retrieval of verbal and nonverbal visual and tactile information (8,9,26).…”

“…More precisely, it has been proposed that the two midventrolateral prefrontal cortical areas 45 and 47/12 are critical for the active selection and retrieval of information from memory when stimuli are related to other stimuli/contexts in multiple and more-or-less equiprobable ways, so that memory retrieval cannot be a matter of mere recognition of the stimuli or supported by strong and unique stimulus-to-stimulus or stimulus-to-context associations (7). In previous functional neuroimaging studies, we were able to show activity increases that were specific to the midventrolateral prefrontal cortex for the active retrieval of visual and tactile stimuli (8,9). A more recent study has shown that patients with lesions to the ventrolateral prefrontal region, but not those with lesions involving the dorsolateral prefrontal region, show impairments in the active controlled retrieval of the visual contexts within which words had appeared (10).…”