Role of the Prefrontal Cortex in the Foreperiod Effect: TMS Evidence for Dual Mechanisms in Temporal Preparation

May combine two claims.

In Experiment 1, the FPn x FPn-1 interaction was significant, reflecting asymmetry of sequential effects, greatest for the shortest FPn and smallest/virtually absent for the longest FPn.

“The FP n 3 FP n -1 interaction, concerning asymmetry of sequential effects, was also significant (F 4,32 = 23.6,P < 0.001; F 4,32 = 11.4,P < 0.001; F 2.4,19.6 = 6.5, Adj.P < 0.01 for rDLPFC, left DLPFC, and right AG, respectively).This effect was primarily due to the differential contribution of the FP n -1 to the RT at each of the 3 current FPs, being greatest for the shortest FP n and smallest,”

May combine two claims.

The results of 2 experiments indicate that the FP effect was significantly reduced after TMS over the rDLPFC, whereas no effect was observed after stimulation of a left contralateral site and the right angular gyrus.

“The results of 2 experiments (with simple and choice RT tasks, respectively) indicate that the FP effect was significantly reduced after TMS over the rDLPFC, whereas no effect was observed after stimulation of a left contralateral site and the right angular gyrus.”

May combine two claims.

In Experiment 2, no TMS block main effect was observed for any stimulation site, indicating RTs were not nonspecifically modified by TBS.

“No TMS block main effect was observed for any site of stimulation, indicating that RTs were not nonspecifically modified by the TBS.”

May combine two claims.

In Experiment 1, no TMS block main effect was observed for any site of stimulation, indicating that RTs were not nonspecifically modified by the TBS.

“No TMS block main effect was observed for any site of stimulation, indicating that RTs were not nonspecifically modified by the TBS.”

The quote only partly states this claim.

In Experiment 2, the TMS block x FPn interaction was significant for the rDLPFC session only.

“As for Experiment 1, the TMS block 3 FP n interaction was significant for the rDLPFC session only (F 4,32 = 4.5, P < 0.01).”

May combine two claims.

In Experiment 1, the FP effect and asymmetric sequential effects, usually found in a variable FP paradigm, were replicated.

“The FP effect and the asymmetric sequential effects, usually found in a variable FP paradigm, were replicated in Experiment 1.”

May combine two claims.

In Experiment 1, after TMS over rDLPFC, RTs on the longest FPn were slower relative to baseline (104%), whereas RTs on the shortest FPn were faster (97%), and the difference between these values was significant (P < 0.01).

“In this case only, indeed, the RTs on the longest FP n were slower with respect to the baseline (104%), whereas the RTs on the shortest FP n were faster (97%), the difference between these 2 values being significant following post hoc Tukey's comparisons (P < 0.01).”

May combine two claims.

In Experiment 1, the RT difference between the shortest and longest FPn was 43 ms in the baseline block and 26 ms in the post-TMS block, a significant reduction (P < 0.001).

“This conclusion was corroborated contrasting the RT difference between the shortest and the longest FP n in the baseline block (43 ms) and the same RT difference in the post-TMS (26 ms) by means of planned comparisons (P < 0.001).”

May combine two claims.

In Experiment 2 overall ANOVA, post-TMS RTs were slower after a long FPn and faster after a short FPn compared with baseline values (101% vs. 99%).

“Post hoc comparisons indicated that post-TMS RTs were slower after a long FP n and faster after a short FP n with respect to the baseline values (101% vs. 99%; P < 0.05).”

May combine two claims.

In Experiment 1, the main effect of current FP (FPn) was significant, with RTs slowest for the shortest FP of 0.5 s compared with middle and longest FPs, and no difference between 1.0 and 1.5 s.

“First, the main effect of FP n was obtained (F 2,16 = 28.7,P < 0.001; F 1.1,9.1 = 40.1,adjusted P < 0.001; F 2,16 = 34.1,P < 0.001 for rDLPFC, left DLPFC, and right AG, respectively).Post hoc Tukey's HSD comparisons showed that RTs were slowest for the shortest FP of 0.5 s as compared with the middle and longest FPs (for all, P < 0.001), but there was no difference among the RTs for FPs of 1.0 and”

May combine two claims.

In Experiment 2, current RTs were slower following a middle FPn-1 trial than a shortest FPn-1 trial, and slower following a longest FPn-1 trial than a middle one, except for right AG where middle vs longest was not significant.

“The post hoc comparisons showed that current RTs were slower following a middle FP n -1 trial than a shortest FP n -1 trial and, in turn, following a longest FP n -1 trial than a middle one (for the right AG, the difference between the middle FP n -1 and the longest one was not significant, for all the other comparisons, P < 0.05).”

May combine two claims.

In Experiment 2, the FPn x FPn-1 interaction was significant for rDLPFC and left DLPFC, with a tendency for right AG.

“The FP n 3 FP n -1 interaction, concerning the asymmetric sequential effects, was also significant (F 1.8,14.8= 5.1, Adj.P = 0.02; F 4,32 = 12.7, P < 0.001 for the rDLPFC and left DLPFC, respectively; and a tendency for the right AG, F 1.5, 12 = 3.9, Adj.P = 0.059).”

May combine two claims.

In Experiment 1, the overall ANOVA showed a significant interaction between TMS site and FPn (F=2.8, P<0.05), indicating that the FP effect was selectively modulated after TMS over the rDLPFC.

“The only significant effect obtained in the overall ANOVA was the interaction between TMS site and FP n (F 4,32 = 2.8, P < 0.05), indicating that the FP effect was selectively modulated after TMS over the rDLPFC (see Fig. 4).”

May combine two claims.

In Experiment 1, the TMS block x FPn interaction was significant only for the rDLPFC session, indicating that the FP effect was reduced in the post-TMS block compared with baseline during the rDLPFC session.

“More critically, the TMS block 3 FP n interaction was significant only for the rDLPFC session (F 2,16 = 7.2, P < 0.01), indicating that the FP effect was reduced in the post-TMS block as compared with the baseline block during the rDLPFC session.”

May combine two claims.

The FPn x TMS site x block interaction was significant, confirming the selective reduction of the FP effect after stimulation of the rDLPFC.

“Specifically, the FP n 3 TMS site 3 block interaction was significant [F 4,32 = 3.4,P < 0.05; F 8,64 = 2.3, P < 0.05 for the Experiments 1 and 2, respectively], confirming the selective reduction of the FP effect after stimulation of the rDLPFC).”

May combine two claims.

In Experiment 1, the main effect of preceding FP (FPn-1) was significant, with current RTs slower following a longest FPn-1 trial than a shortest FPn-1 trial.

“The main effect of FP n -1 also reached significance (F 1.1,8.8= 5.5, Adj.P < 0.05; F 1.2,9.9= 15.3,Adj.P < 0.01; F 1.3,10.1 = 17.2,Adj.P = 0.001 for rDLPFC, left DLPFC, and right AG, respectively).The post hoc comparisons showed that current RTs were slower following a longest FP n -1 trial than a shortest FP n -1 trial (for all, P < 0.01).”

May combine two claims.

In Experiment 2, planned comparisons confirmed that in the second post-TMS block after rDLPFC TMS, sequential effects were basically symmetric, as they were also present on the longest FPn.

“This analysis was significant (F 1,8 = 13.9,P < 0.01), confirming that, in the second post-TMS block, sequential effects were basically symmetric, as they were also present on the longest FP n .”

May combine two claims.

In Experiment 2, for rDLPFC only, RTs on the longest FPn were slower than baseline (103%), whereas RTs on the shortest FPn were slightly faster (99%), with the difference between these values significant.

“In this case only, the RTs on the longest FP n were slower with respect to the baseline block (103%), whereas the RTs on the shortest FP n were slightly faster (99%), the difference between these 2 values being significant on post hoc Tukey's comparisons (P < 0.05).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The post-TMS period investigated was about 6 min long for the simple RT task in Experiment 1 and 15 min long for the choice RT task in Experiment 2.

“This period was about 6 min long for the simple RT task in Experiment 1 and 15 min long for the choice RT task in Experiment 2.”

May combine two claims.

The more symmetric sequential effects in the second post-TMS block were confirmed by a significant FPn x FPn-1 x TMS block interaction, obtained only for a direct comparison between baseline and second post-TMS block.

“This was confirmed by the presence of a significant FP n 3 FP n -1 3 TMS block interaction, although this was obtained only for a direct comparison between the baseline block and the second post-TMS one, namely, the block in which the effects of the TBS would be expected to be stronger (see Huang and others 2005).”

• cites Huang and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim. May combine two claims.

The coordinates for TMS sites were taken from an fMRI study by Lewis and Miall (2003), in which activation of right and left DLPFC and right AG was found during a temporal discrimination task for both sub- and suprasecond intervals.

“Those coordinates were taken from an fMRI study by Lewis and Miall (2003), in which activation of the right and left DLPFC and of the right AG was found during a temporal discrimination task for both sub-and suprasecond intervals.”

• cites Lewis and Miall 2003 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Fewer than 3.2% of trials were excluded, with no difference across conditions.

“Fewer than 3.2% of trials were excluded with no difference across conditions.”

May combine two claims.

Unpublished data from our laboratory show that the learning period for the FP phenomena, if any, is very brief, as after an initial block of 60 trials, the FP and sequential effects are already present with the same magnitude as in subsequent blocks.

“Unpublished data from our laboratory show that the learning period for the FP phenomena, if any, is very brief as after an initial block of 60 trials, the FP and sequential effects are already present with the same magnitude as in subsequent blocks.”

May combine two claims.

The reduction of the FP effect as a consequence of TMS acting specifically on the rDLPFC was replicated, whereas no TMS effect was obtained on the left DLPFC and the right AG.

“In particular, the reduction of the FP effect as a consequence of TMS acting specifically on the rDLPFC was replicated, whereas no TMS effect was obtained on the left DLPFC and the right AG.”

May combine two claims.

TMS over rDLPFC reduced the FP effect, confirming the role of rDLPFC in the occurrence of this effect.

“Moreover, a role of the rDLPFC was demonstrated for the FP effect.”

• Also stated in: § Discussion · boosted

  “On the other hand, after TMS over the rDLPFC, a reduction in the FP effect was observed, confirming the role of this area in the occurrence of this effect, as already shown by a recent neuropsychological study (Stuss and others 2005).”

• cites Stuss and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

In Experiment 1, the result cannot be used to corroborate any dual-process model of the FP phenomena because a dissociation between FP and sequential effects was not clearly obtained (the FPn-1 effect also showed a tendency toward being reduced after TMS over rDLPFC).

“This result is interesting per se but cannot be used to corroborate any dual-process model of the FP phenomena.A dissociation between the FP and the sequential effects was not clearly obtained in this experiment because the effect of the FP n -1 also showed a tendency toward being reduced after the TMS over the rDLPFC.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The order in which the 3 areas were stimulated was counterbalanced across participants, such that each area was stimulated in the first day session on an equal number of participants.

“The order in which the 3 areas were stimulated was counterbalanced across participants, such that each area was stimulated in the first day session on an equal number of participants.”

Classified as probably not a substantial claim. May combine two claims.

The FP effect consists of reaction times decreasing as the foreperiod increases, typically observed when a range of variable FPs occur randomly and equiprobably.

“The FP effect, usually observed when a range of variable FPs occur randomly and equiprobably, consists of reaction times (RTs) decreasing as the FP increases.”

• Also stated in: § Introduction · plain

  “When FPs at a number of points within a fixed range occur randomly over trials but with the same a priori probability, RTs are longer for shorter FPs and shorter for middle and longer FPs.”

• cites Woodrow 1914 sourceNot checked — no full text of the source
• cites Niemi and Nääänen 1981Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

With 20 s TBS stimulation, the time window of reduced excitability was estimated to last up to 20 min.

“With 20 s stimulation, the time window of reduced excitability was estimated to last up to 20 min.”

• cites Di Lazzaro and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Huang and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

The range of FPs used in Stuss et al (2005) (3-7 s) might suggest an alternative explanation of a deficit of the vigilance system in maintaining attention over a long period, instead of a monitoring process, in the case of right prefrontal lesions.

“Moreover, the range of FPs used in the study of Stuss and others (2005) (i.e., 3--7 s) might suggest the alternative explanation of a deficit of the vigilance system in maintaining attention over a long period of time, instead of a monitoring process, in the case of right prefrontal lesions.”

May combine two claims.

In variable FP paradigms, sequential effects occur such that longer FPs on the preceding trial produce slower RTs on the current trial, particularly for the shortest current FPs.

“Moreover, in such paradigms, RTs increase as a function of the preceding FP (i.e., sequential effects).”

• Also stated in: § Introduction · plain

  “Moreover, sequential effects are also usually observed with this paradigm: longer FPs on the preceding trial produce slower RTs on the current one (Karlin 1959;Niemi and Na¨a¨ta¨nen 1981).This is particularly the case for the shortest current FPs.”

• cites Karlin 1959 sourceNot checked — no full text of the source
• cites Niemi and Nääänen 1981Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

In Experiment 2, fewer than 1.8% of trials were excluded from analysis.

“Fewer than 1.8% of trials were excluded.”

Classified as probably not a substantial claim.

The reduction of cortical excitability of the motor cortex reaches a maximum from 7 to 14 min after TBS.

“As the reduction of the cortical excitability of the motor cortex reaches a maximum from 7 to 14 min after TBS (Di Lazzaro and others 2005; Huang and others 2005), a similar time course can be expected in the case of the rDLPFC.”

• cites Di Lazzaro and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Huang and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

The rDLPFC is likely the region responsible for the strategic process producing the FP effect, which controls preparedness by checking the conditional probability of IS occurrence.

“Stuss and others (2005) suggest that the rDLPFC is likely to be the region responsible for the strategic process producing the FP effect, which controls the state of preparedness by checking the conditional probability of IS occurrence.”

• cites Stuss and others 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S1 (asserted).

The conditioning view predicts that sequential effects, if present, must inevitably be asymmetric, due to a main role of extinction on the activation strength of the shortest FPs and of reinforcement on the activation strength of longest FPs.

“This account predicts that the sequential effects, if present, must inevitably be asymmetric, due to a main role of extinction on the activation strength of the shortest FPs and of reinforcement on the activation strength of longest FPs.”

• cites Los and van den Heuvel 2001Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The dissociation between the FP effect and the sequential effects produced by TMS of the rDLPFC, especially in Experiment 2, suggests a dual-process account, according to which the 2 effects are likely to be dissociable both functionally and anatomically.

“Moreover, the dissociation between the FP effect and the sequential effects produced by TMS of the rDLPFC, especially in Experiment 2, suggests a dual-process account, according to which the 2 (usually interacting) effects are likely to be dissociable both functionally and anatomically.”

• AssumptionThe authors state this as an assumption: According to the dual-process model, sequential effects per se can be explained by assuming an enhancement in arousal following a short FPn-1 and a decrease following a long FPn-1, whatever the current FPn.

May combine two claims.

The study obtained site controls (rDLPFC vs. all other sites and no TMS) and a task control (FP vs. sequential effects dissociation) for its effects.

“Thus, we obtained site controls (i.e., rDLPFC vs. all other sites and no TMS) and a task control for our effects (i.e., FP vs. sequential effects dissociation).”

May combine two claims.

This is the first study in which an effect of the TBS parameters was demonstrated on behavioral variables (RTs) not directly linked to the measure of the motor cortex excitability, indicating its usefulness in cognitive neuroscience as a feasible alternative to other kinds of off-line stimulation.

“To the best of our knowledge, this is the first study in which an effect of the TBS parameters was demonstrated on behavioral variables (i.e., RTs) not directly linked to the measure of the motor cortex excitability, indicating its usefulness in cognitive neuroscience, as a feasible alternative to other kinds of off-line stimulation.”

May combine two claims.

The rDLPFC region controlling this process would be permanently damaged in the neuropsychological patients studied by Stuss and others (2005) and compromised transiently in the present study using TMS.

“The rDLPFC region controlling such process would be permanently damaged in the neuropsychological patients studied by Stuss and others (2005) and compromised transiently in the present study using TMS.”

• cites Stuss and others (2005)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The present study demonstrated that the rDLPFC is a critical locus of the FP effect, as a reduction in this effect is obtained after TMS over that area.

“In conclusion, the present study demonstrated that the rDLPFC is a critical locus of the FP effect, as a reduction in this effect is obtained after TMS over that area.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The observation of symmetric sequential effects when the FP is attenuated may be tentatively accounted for by a recently proposed dual-process model.

“The observation of symmetric sequential effects when the FP is attenuated may be tentatively accounted for by a recently proposed dual-process model (A. Vallesi and T. Shallice, in preparation).”

• cites A. Vallesi and T. Shallice, in preparationNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• AssumptionThe authors state this as an assumption: According to the dual-process model, sequential effects per se can be explained by assuming an enhancement in arousal following a short FPn-1 and a decrease following a long FPn-1, whatever the current FPn.

May combine two claims.

A dissociation between the FP effect and sequential effects was obtained, so the hypothesis of a common mechanism underlying both effects is not supported.

“As dissociation between the 2 effects has been obtained, the hypothesis of a common mechanism underlying both effects is not supported.”

May combine two claims.

In Experiment 2, a dissociation between the FP effect and the sequential effects was obtained after stimulating the rDLPFC: the FP effect was significantly reduced, whereas the sequential effects were not influenced in magnitude.

“Moreover, in Experiment 2, a dissociation between the FP effect and the sequential effects was obtained after stimulating the rDLPFC: the FP effect was significantly reduced, whereas the sequential effects were not influenced in magnitude.”

May combine two claims.

After 6-7 min from TMS of the rDLPFC, sequential effects become more symmetric, whereas the FP effect decreases.

“after 6--7 min from TMS of the rDLPFC, the sequential effects become more symmetric, whereas the FP effect decreases.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In Los and Heslenfeld (2005), the CNV was used as a covert index of nonspecific preparation during a variable FP paradigm employing temporal cuing.

“In that study, the contingent negative variation (CNV) was used as a covert index of nonspecific preparation, during a variable FP paradigm employing temporal cuing.”

• cites Los and Heslenfeld (2005) sourceNot checked — no full text of the source