The Right Frontopolar Cortex Is Involved in Visual-Spatial Prospective Memory
Citation: Costa A, Oliveri M, Barban F, Bonn` S, Koch G, et al. (
The Right Frontopolar Cortex Is Involved in Visual-Spatial Prospective Memory
Alberto Costa 0
Massimiliano Oliveri 0
Francesco Barban 0
Sonia Bonn` 0
Giacomo Koch 0
Carlo Caltagirone 0
Giovanni A. Carlesimo 0
Sam Gilbert, University College London, United Kingdom
0 1 Clinical and Behavioural Neurology Laboratory, Istituto Di Ricovero e Cura a Carattere Scientifico Santa Lucia Foundation , Rome , Italy , 2 Psychology Department, Palermo University , Palermo, Italy, 3 Clinical Neurology , ''Tor Vergata'' University , Rome , Italy
The involvement of frontopolar cortex in mediating prospective memory processes has been evidenced by various studies, mainly by means of neuroimaging techniques. Recently, one transcranial magnetic stimulation study documented that transient inhibition of left Brodmann Area (BA) 10 impaired verbal prospective memory. This result raises the issue of whether the BA 10 involvement in prospective memory functioning may be modulated by the physical characteristics of the stimuli used. The present study aimed to investigate the role of the frontopolar cortex in visual-spatial PM by means of the application of inhibitory theta-burst stimulation. Twelve volunteers were evaluated after inhibitory theta-burst stimulation over left BA 10, right BA10 and CZ (control condition). In the prospective memory procedure, sequences of four spatial positions (black squares) each were presented. During the inter-sequence delay, subjects had to reproduce the sequence in the observed order (ongoing task forward) or the reverse order (backward). At the occurrence of a target position, subjects had to press a key on the keyboard (prospective memory score). Recall and recognition of the target positions were also tested. We found that prospective memory accuracy was lower after theta-burst stimulation over right BA10 than CZ (p,0.01), whereas it was comparable in left BA10 and CZ conditions. No significant difference was found among the three conditions on recall and recognition of target positions and on ongoing task performance. Our findings provide a novel strong evidence for a specific involvement of right frontopolar cortex in visual-spatial prospective memory. In the context of previous data providing evidence for left BA 10 involvement in verbal prospective memory, our results also suggest material-specific lateralization of prospective memory processes in BA 10.
-
In recent years, reliable data has been reported on involvement
of the rostral frontal brain regions in mediating the ability to carry
out delayed intentions (i.e., prospective memory; PM). Indeed,
since Burgess et al. [1] and Okuda et al [2] published pivotal data
on the effect of prefrontal cortex lesions on PM functioning and
the functional brain correlates of PM, the role of the frontal pole in
PM processes has been investigated and confirmed by means of
functional neuroimaging techniques. In healthy individuals,
metabolic and hemodynamic changes in Brodmann Area (BA)
10 were repeatedly found to be significantly related to PM task
performance and the hypothesis of a dynamic interplay between
the lateral and medial portions of this area was advanced (for a
review of main studies, see [3]). In fact, the PM-related activity of
the rostral frontal regions has been consistently detected in both
subtraction and conjunction designs, regardless of the material
adopted (e.g., shapes, words, figures) and the attentional demands
of the procedures [2,47]. Moreover, as Reynolds et al.s data
indicate, an increase in neural activity in this area may be
specifically related to the implementation of PM processes and not
to other cognitive processes (e.g., working memory) implicated in
the execution of a PM task [8]. A clear-cut association between BA
10 activity and PM functioning was further confirmed in one
transcranial magnetic stimulation (TMS) study. In this study the
transient inhibition of left lateral BA 10 activity by means of
offline application of continuous Theta Burst Stimulation (cTBS) was
shown to significantly worsen healthy subjects ability to activate
prospective intention without affecting episodic recollection of the
events [9].
To summarize, various evidence suggests that BA 10 activity has
a key role in supporting PM abilities. However, it is less clear
whether, within the frontal pole, we can hypothesize an
hemispheric specialization on control of PM processes. Indeed,
an asymmetrical pattern of neural activity related to the
performance of a PM task, characterized by stronger activation
of the left than the right frontal pole, has been evidenced by
functional neuroimaging data [5,6,10,11]. Some of these findings
suggest basic dominance of the left hemisphere in PM operations
regardless of the kind of material used (e.g., pictures, complex
scenes or letter processing) [5,12,13]. Other studies have
demonstrated different involvement of the left and right frontal (...truncated)