Thursday, March 28, 2013

Journal Alert - NEUROPSYCHOLOGIA---issue on neural timing

Journal Name:   NEUROPSYCHOLOGIA (ISSN: 0028-3932)
Issue:          Vol. 51 No. 2, 2013
IDS#:           102JB
Alert Expires:  10 JAN 2014
Number of Articles in Issue:  18 (18 included in this e-mail)
Organization ID:  c4f3d919329a46768459d3e35b8102e6
Note:  Instructions on how to purchase the full text of an article and Thomson Reuters Science Contact information are at the end of the e-mail.

*Pages: 187-190 (Editorial Material)
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The cognitive neuroscience of time perception: How psychological studies might help to dissect the timing system

Wearden, JH

*NEUROPSYCHOLOGIA*, 51 (2):187-190; SI JAN 2013

It is argued that the cognitive neuroscience of time perception does not
make sufficient use of a range of experimental techniques and
theoretical approaches which might be useful in "dissecting" the human
timing system, and thus helping to uncover its neural basis. These
techniques are mostly inspired by scalar expectancy theory, but do not
depend on acceptance of that model. Most of the methods result in the
same physical stimuli giving rise to systematically different time
judgements, thus they avoid problems of control which have haunted some
areas of the cognitive neuroscience of timing. Among the possibilities
are (a) changing the basic duration judgement of stimuli and events, (b)
manipulating working memory and reference memories for duration, and (c)
changing temporal decision processes. (C) 2012 Published by Elsevier


*Pages: 191-196 (Article)
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The neural correlates of temporal judgments in the duration bisection task

Lindbergh, CA; Kieffaber, PD

*NEUROPSYCHOLOGIA*, 51 (2):191-196; SI JAN 2013

Decision processes related to interval timing are commonly examined
using the duration bisection procedure-a well-established timekeeping
task in which participants make judgments about whether a series of
"probes" are closer in duration to a "short" anchor duration or a "long"
anchor duration. The specific information used during bisection
categorization has been a subject of debate. Recent research involving
the Contingent Negative Variation (CNV) suggests that the "short" anchor
duration and a value near the geometric mean (GM) of the short and long
anchors are among the critical pieces of information used during
bisection categorization judgements. The present study examined a
corollary of this claim, that memory comparison and decision-making
processes related to the temporal judgments are completed prior to probe
offset when probe durations are perceived to be "long;" testing the
hypotheses that (I) response times would be significantly longer for
"short" relative to "long" categorizations and that (2) there would be
significant differences in ERPs time-locked to probe offset between
probes judged to be "short" and "long." Both of these predictions were
realized in the results, providing strong support for the assertion that
a value near the GM-likely the point of subjective equality (PSE)-is
among the critical information used during bisection categorization
judgments.. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 197-210 (Article)
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Adaptive tuning of perceptual timing to whole body motion

Binetti, N; Siegler, IA; Bueti, D; Doricchi, F

*NEUROPSYCHOLOGIA*, 51 (2):197-210; SI JAN 2013

In a previous work we have shown that sinusoidal whole-body rotations
producing continuous vestibular stimulation, affected the timing of
motor responses as assessed with a paced finger tapping (PFT) task
(Binetti et al. (2010). Neuropsychologia, 48(6), 1842-1852). Here, in
two new psychophysical experiments, one purely perceptual and one with
both sensory and motor components, we explored the relationship between
body motion/vestibular stimulation and perceived timing of acoustic
events. In experiment 1, participants were required to discriminate
sequences of acoustic tones endowed with different degrees of
acceleration or deceleration. In this experiment we found that a tone
sequence presented during acceleratory whole-body rotations required a
progressive increase in rate in order to be considered temporally
regular, consistent with the idea of an increase in "clock" frequency
and of an overestimation of time. In experiment 2 participants produced
self-paced taps, which entailed an acoustic feedback. We found that
tapping frequency in this task was affected by periodic motion by means
of anticipatory and congruent (in-phase) fluctuations irrespective of
the self-generated sensory feedback. On the other hand, synchronizing
taps to an external rhythm determined a completely opposite modulation
(delayed/counter-phase). Overall this study shows that body
displacements "remap" our metric of time, affecting not only motor
output but also sensory input. (C) 2012 Elsevier Ltd. All rights


*Pages: 211-219 (Article)
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Cognitive function predicts neural activity associated with pre-attentive temporal processing

Foster, SM; Kisley, MA; Davis, HP; Diede, NT; Campbell, AM; Davalos, DB

*NEUROPSYCHOLOGIA*, 51 (2):211-219; SI JAN 2013

Temporal processing, or processing time-related information, appears to
play a significant role in. a variety of vital psychological functions.
One of the main confounds to assessing the neural underpinnings and
cognitive correlates of temporal processing is that behavioral measures
of timing are generally confounded by other supporting cognitive
processes, such as attention. Further, much theorizing in this field has
relied on findings from clinical populations (e.g., individuals with
schizophrenia) known to have temporal processing deficits. In this
study, we attempted to avoid these difficulties by comparing temporal
processing assessed by a pre-attentive event-related brain potential
(ERP) waveform, the mismatch negativity (MMN) elicited by time-based
stimulus features, to a number of cognitive functions within a
non-clinical sample. We studied healthy older adults (without dementia),
as this population inherently ensures more prominent variability in
cognitive function than a younger adult sample, allowing for the
detection of significant relationships between variables. Using
hierarchical regression analyses, we found that verbal memory and
executive functions (i.e., planning and conditional inhibition, but not
set-shifting) uniquely predicted variance in temporal processing beyond
that predicted by the demographic variables of age, gender, and hearing
loss. These findings are consistent with a frontotemporal model of MMN
waveform generation in response to changes in the temporal features of
auditory stimuli. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 220-234 (Article)
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Time perception in children: A neurodevelopmental approach

Droit-Volet, S

*NEUROPSYCHOLOGIA*, 51 (2):220-234; SI JAN 2013

In this review, we discuss behavioral studies on time perception in
healthy children that suggest the existence of a primitive "sense" of
time in infants as well as research that has revealed the changes in
time judgments that occur throughout childhood. Moreover, a distinction
is made between implicit and explicit time judgments in order to take
account of the different types of temporal judgments that emerge across
ages. On the basis of both the neurobiological model of the internal
clock proposed by Matell and Meck (2000), and of results of imaging
studies in human adults, we then try to identify which of the neural
structures underlying this primitive sense of time mature faster and
which mature more slowly in order to explain the age-related variance in
time judgments. To this end, we also present the small number of timing
studies conducted among typically and non-typically developing children
that have used functional magnetic resonance imaging (fMRI) as well as
those that have assessed the cognitive capacities of such children on
the basis of various neuropsychological tests. (C) 2012 Elsevier Ltd.
All rights reserved.


*Pages: 235-266 (Article)
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Timing deficits in attention-deficit/hyperactivity disorder (ADHD): Evidence from neurocognitive and neuroimaging studies

Noreika, V; Falter, CM; Rubia, K

*NEUROPSYCHOLOGIA*, 51 (2):235-266; SI JAN 2013

Relatively recently, neurocognitive and neuroimaging studies have
indicated that individuals with attention-deficit/hyperactivity disorder
(ADHD) may have deficits in a range of timing functions and their
underlying neural networks. Despite this evidence, timing deficits in
ADHD are still somewhat neglected in the literature and mostly omitted
from reviews on ADHD. There is therefore a lack of integrative reviews
on the up-to-date evidence on neurocognitive and neurofunctional
deficits of timing in ADHD and their significance with respect to other
behavioural and cognitive deficits. The present review provides a
synthetic overview of the evidence for neurocognitive and
neurofunctional deficits in ADHD in timing functions, and integrates
this evidence with the cognitive neuroscience literature of the neural
substrates of timing. The review demonstrates that ADHD patients are
consistently impaired in three major timing domains, in motor timing,
perceptual timing and temporal foresight, comprising several timeframes
spanning milliseconds, seconds, minutes and longer intervals up to
years. The most consistent impairments in ADHD are found in sensorimotor
synchronisation, duration discrimination, reproduction and delay
discounting. These neurocognitive findings of timing deficits in ADHD
are furthermore supported by functional neuroimaging studies that show
dysfunctions in the key inferior fronto-striato-cerebellar and
fronto-parietal networks that mediate the timing functions. Although
there is evidence that these timing functions are inter-correlated with
other executive functions that are well established to be impaired in
the disorder, in particular working memory, attention, and to a lesser
degree inhibitory control, the key timing deficits appear to survive
when these functions are controlled for, suggesting independent
cognitive deficits in the temporal domain. There is furthermore strong
evidence for an association between timing deficits and behavioural
measures of impulsiveness and inattention, suggesting that timing
problems are key to the clinical behavioural profile of ADHD. Emerging
evidence shows that the most common treatment of ADHD with the dopamine
agonist and psychostimulant Methylphenidate attenuates most timing
deficits in ADHD and normalises the abnormally blunted recruitment of
the underlying fronto-striato-cerebellar networks. Timing function
deficits in ADHD, therefore, next to executive function deficits, form
an independent impairment domain, and should receive more attention in
neuropsychological, neuroimaging, and pharmacological basic research as
well as in translational research aimed to develop pharmacological or
non-pharmacological treatment of abnormal timing behaviour and cognition
in ADHD. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 267-274 (Article)
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Deciphering the impact of cerebellar and basal ganglia dysfunction in accuracy and variability of motor timing

Claassen, DO; Jones, CRG; Yu, MH; Dirnberger, G; Malone, T; Parkinson,
M; Giunti, P; Kubovy, M; Jahanshahi, M

*NEUROPSYCHOLOGIA*, 51 (2):267-274; SI JAN 2013

Studies in motor timing have shown that the basal ganglia and cerebellum
play an important role in temporal processing. Timing studies in
Cerebellar/ataxic Disorders (CD) and Parkinson's disease (PD) patients
contrast the roles of the cerebellum and basal ganglia in motor timing.
Here, we used a synchronization-continuation task to compare accuracy
and variability of motor timing during repetitive tapping. We compared
data collected for the present study - from patients with CD and healthy
controls - to data from a previous study with patients with PD. We asked
participants to tap at Inter-stimulus Intervals (ISIs) of 250, 500,
1000, and 2000 ms. Using Linear Mixed Models (LMMs), we explored how
ISI, Task Phase, and Diagnosis interacted to determine the (i) the
accuracy and (ii) the variability of tapping. In our analysis of
accuracy, we found evidence that during the synchronization phase, at
ISI=250 ms, CD patients lagged 'behind the beat'; whereas our previous
work has suggested that medicated PD patients hasten 'ahead of the
beat'. In our analysis of variability, we observed that at ISIs below
1000 ms, CD patients showed greater variability in motor timing than the
healthy controls, while PD patients showed less variability than CD
patients and healthy controls during the synchronization phase at the
1000 ms ISI. These results highlight the differential performance on
explicit motor timing between patients with disorders of the cerebellum
and basal ganglia. Our results illustrate a novel approach to discerning
cognitive control of motor timing. (C) 2012 Elsevier Ltd. All rights


*Pages: 275-283 (Article)
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How does one night of sleep deprivation affect the internal clock?

Casini, L; Ramdani-Beauvir, C; Burle, B; Vidal, F

*NEUROPSYCHOLOGIA*, 51 (2):275-283; SI JAN 2013

Twelve subjects performed two temporal tasks, one explicit (Experiment
1) and one implicit (Experiment 2) after one night of sleep deprivation
and after one night of normal rest. Experiment 1 involved a 1100-ms
duration production task, and in Experiment 2 subjects performed a word
identification task requiring implicit estimation of vowel duration
(around 150 ms). One night of sleep deprivation had the same pattern of
effect on explicit timing in the suprasecond range and implicit timing
in the millisecond range. Specifically, sleep deprivation induced
productions of shorter intervals in the duration production task and
estimation of segmental durations as being longer in the word
identification task. Both results are consistent with an acceleration of
pacemaker rate.
Moreover, in both experiments, we found a correlation between the
alertness level of participants and the size of the effect. Therefore,
sleep deprivation, which physiologically manipulates cortical arousal
level, produced similar performance modulation in suprasecond explicit
and subsecond implicit tasks suggesting a common mechanism. (C) 2012
Elsevier Ltd. All rights reserved.


*Pages: 284-292 (Article)
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Differential effects of amphetamine and haloperidol on temporal reproduction: Dopaminergic regulation of attention and clock speed

Lake, JI; Meck, WH

*NEUROPSYCHOLOGIA*, 51 (2):284-292; SI JAN 2013

Healthy volunteers were tested on 7-s and 17-s peak-interval timing
procedures following D-amphetamine (20 mg-oral), haloperidol (2
mg-oral), and placebo treatments in order to assess the dopaminergic
regulation of temporal processing. Individual differences were observed
in the drug effects such that two different patterns of timing behavior
emerged. In the first pattern, D-amphetamine produced proportional
leftward shifts of the timing functions while haloperidol produced
proportional rightward shifts. This symmetrical pattern of results
suggests that clock speed is regulated by the effective level of
dopamine, i.e., D-amphetamine increases clock speed and haloperidol
decreases clock speed. The second pattern was the opposite of the first
pattern and was revealed by D-amphetamine producing proportional
rightward shifts of the timing functions while haloperidol produced no
reliable effect. This asymmetrical pattern of results is consistent with
an explanation in which attention toward the stimulant-induced euphoria
produced by D-amphetamine diminishes the attentional resources available
for temporal processing, thereby diluting any drug-induced changes in
clock speed. The result of increased competition and time-sharing
between these two dimensions (e.g., attention towards feelings of
euphoria versus attention towards the passage of time) leads to the
underestimation/overproduction of temporal intervals. Interestingly,
participants that displayed the 'clock-speed' pattern liked
D-amphetamine significantly less than participants that displayed the
'attention' pattern and were more variable in a simple reaction time
task than other participants. These results suggest that individuals
with a higher degree of sensitivity to time are also more sensitive to
their feelings of stimulant-induced euphoria and drug liking-suggesting
that internal clock and reward pathways share common dopaminergic
pathways. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 293-308 (Article)
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Epistasis effects of dopamine genes on interval timing and reward magnitude in humans

Balci, F; Wiener, M; Cavdaroglu, B; Coslett, HB

*NEUROPSYCHOLOGIA*, 51 (2):293-308; SI JAN 2013

We tested human participants on a modified peak procedure in order to
investigate the relation between interval timing and reward processing,
and examine the interaction of this relation with three different
dopamine-related gene polymorphisms. These gene polymorphisms affected
the expression of catechol-o-methyltransferase, which catabolizes
synaptic dopamine primarily in the prefrontal cortex (COMT Val158Met
polymorphism), D2 dopamine receptors primarily in the striatum
(DRD2/ANKK1-Taq1a polymorphism), and dopamine transporters, which clear
synaptic dopamine in the striatum (DAT 3' VNTR variant). The inclusion
of these polymorphisms allowed us to investigate dissociable aspects of
the dopamine system and their interaction with reward magnitude
manipulations in shaping timed behavior. These genes were chosen for
their roles in reward processing and cortico-striatal information
processing that have been implicated for interval timing. Consistent
with recent animal studies, human participants initiated their timed
anticipatory responding earlier when expecting a larger reward in the
absence of any changes in the timing of response termination or
perceived time. This effect however was specific to two out of four
evaluated COMT and DRD2 polymorphism combinations that lead to high
prefrontal dopamine coupled with high D2 density and low prefrontal
dopamine coupled with low D2 density. Larger rewards also decreased
timing precision indices, some of which interacted with the COMT
polymorphism. Furthermore, the COMT polymorphism that leads to higher
prefrontal dopamine resulted in weaker manifestation of memory
variability (relative to threshold variability) in timed behavior. There
was no effect of DAT polymorphisms on any of the core behavioral
measures. These results suggest that the reward modulates decision
thresholds rather than clock speed, and that these effects are specific
to COMT and DRD2 epistasis effects that presumably constitute a balanced
prefrontal and striatal dopamine transmission. (C) 2012 Elsevier Ltd.
All rights reserved.


*Pages: 309-319 (Article)
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Functional anatomy of timing differs for production versus prediction of time intervals

Coull, JT; Davranche, K; Nazarian, B; Vidal, F

*NEUROPSYCHOLOGIA*, 51 (2):309-319; SI JAN 2013

Timing is required both for estimating the duration of a currently
unfolding event, or predicting when a future event is likely to occur.
Yet previous studies have shown these processes to be neuroanatomically
distinct with duration estimation generally activating a distributed,
predominantly right-sided, fronto-striatal network and temporal
prediction activating left-lateralised inferior parietal cortex. So far,
these processes have been examined independently and using widely
differing paradigms. We used fMRI to identify and compare the neural
correlates of duration estimation, indexed by temporal reproduction, to
those of temporal prediction, indexed by temporal orienting, within the
same experimental paradigm. Behavioural data confirmed that accurate
representations of the cued interval were evident for both temporal
reproduction and temporal orienting tasks. Direct comparison of temporal
tasks revealed activation of a right-lateralised fronto-striatal network
when timing was measured explicitly by a temporal reproduction task but
left inferior parietal cortex, left premotor cortex and cerebellum when
timing was measured implicitly by a temporal orienting task. Therefore,
although both production and prediction of temporal intervals required
the same representation of time for their successful execution, their
distinct neural signatures likely reflect the different ways in which
this temporal representation was ultimately used: either to produce an
overt estimate of an internally generated time interval (temporal
reproduction) or to enable efficient responding by predicting the offset
of an externally specified time interval (temporal orienting). This
cortical lateralization may reflect right-hemispheric specificity for
overtly timing a currently elapsing duration and left-hemispheric
specificity for predicting future stimulus onset in order to optimize
information processing. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 320-325 (Article)
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Dissociation of formal and temporal predictability in early auditory evoked potentials

Schwartze, M; Farrugia, N; Kotz, SA

*NEUROPSYCHOLOGIA*, 51 (2):320-325; SI JAN 2013

Perceived regularity among events in the environment allows predictions
regarding the "when" and the "what" dimensions of future events. In this
context, one crucial question concerns the impact and the potentially
optimizing effect, of regular temporal structure on the processing of
"what", or formal, information. The current study addresses this issue
by investigating whether temporal and formal structure interact during
early stages of sensory processing, and by relating the respective
findings to the concept of a predictive bias in brain function. Analyses
were performed on two components of the auditory event-related-potential
of the electroencephalogram, namely the P50 and the N100. Oddball
sequences consisting of frequent standard and infrequent deviant
sinusoidal tones were presented with either regular or irregular
temporal structure in pre-attentive and attentive experimental settings
(Schwartze, Rothermich, Schmidt-Kassow, 82 Kotz, 2011). Temporal
regularity effects on pre-attentive and attentive processing of
deviance. Biological Psychology, 87, 146-151). The results confirm that
the P50 and the N100 amplitudes reliably encode formal and temporal
predictability. Similar patterns of results obtained with pre-attentive
and attentive task instructions, as well as the absence of a significant
interaction of formal and temporal structure suggest that the P50
response may be interpreted as an automatic marker of predictability,
whereas the N100 may represent a more complex marker, in which formal
and temporal structure start interacting as a function of attention. (C)
2012 Elsevier Ltd. All rights reserved.


*Pages: 326-339 (Article)
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Temporal orienting of attention is interfered by concurrent working memory updating

Capizzi, M; Correa, A; Sanabria, D

*NEUROPSYCHOLOGIA*, 51 (2):326-339; SI JAN 2013

A previous dual-task study (Capizzi, Sanabria, & Correa, 2012) showed
that temporal orienting of attention was disrupted by performing a
concurrent working memory task, while sequential effects were preserved.
Here, we recorded event related potentials (ERPs) during single- and
dual-task performance to investigate how this behavioural dissociation
would be expressed in neural activity measures. The single-task
condition required participants to respond to a visual target stimulus
that could be anticipated on the basis of a highly predictive temporal
cue. The dual-task condition introduced a concurrent working memory
task, in which colour information had to be updated on every trial. The
behavioural results replicated our previous findings of impaired
temporal orienting, but preserved sequential effects, under dual-task
relative to single-task conditions. The ERPs results showed that
temporal orienting and sequential effects both modulated the cue-locked
preparatory contingent negative variation (CNV) and the target-locked N2
amplitude and P3 latency under single-task, but not under dual-task
conditions. In contrast to temporal orienting, sequential effects were
also observed at the early target-locked P1 and N1 potentials.
Crucially, only the P1 modulation survived dual-task interference. These
findings provide novel electrophysiological evidence that performance of
a concurrent working memory task may interfere in a selective way with
neural activity specifically linked to temporal orienting of attention.
(C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 340-348 (Article)
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How does Parkinson's disease and aging affect temporal expectation and the implicit timing of eye movements?

de Hemptinne, C; Ivanoiu, A; Lefevre, P; Missal, M

*NEUROPSYCHOLOGIA*, 51 (2):340-348; SI JAN 2013

Anticipatory eye movements are often evoked by the temporal expectation
of an upcoming event. Temporal expectation is based on implicit timing
about when a future event could occur. Implicit timing emerges from
observed temporal regularities in a changing stimulus without any
voluntary estimate of elapsed time, unlike explicit timing.
The neural bases of explicit and implicit timing are likely different.
It has been shown that the basal ganglia (BG) play a central role in
explicit timing. In order to determine the influence of BG in implicit
timing, we investigated the influence of early Parkinson's disease (PD)
and aging on the latency of anticipatory eye movements. We hypothesized
that a deficit of implicit timing should yield inadequate temporal
expectations, and consequently abnormally timed anticipatory eye
movements compared with age-matched controls. To test this hypothesis,
we used an oculomotor paradigm where anticipation of a salient target
event plays a central role. Participants pursued a visual target that
moved along a circular path at a constant velocity. After a randomly
short (1200 ms) or long (2400 ms) forward path, the target reversed
direction, returned to its starting position and stopped.
Target motion reversal caused an abrupt 'slip' of the pursued target
image on the retina and was a particularly salient event evoking
anticipatory eye movements. Anticipatory eye movements were less
frequent in PD patients. However, the timing of anticipation of target
motion reversal was statistically similar in PD patients and control
subjects. Other eye movements showed statistically significant
differences between PD and controls, but these differences could be
attributed to other factors.
We conclude that all anticipatory eye movements are not similarly
impaired in PD and that implicit timing of salient events seems largely
unaffected by this disease. The results support the hypothesis that
implicit and explicit timing are differently affected by BG dysfunction.
(C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 349-357 (Article)
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Oscillatory activity during maintenance of spatial and temporal information in working memory

Roberts, BM; Hsieh, LT; Ranganath, C

*NEUROPSYCHOLOGIA*, 51 (2):349-357; SI JAN 2013

Working memory (WM) processes help keep information in an active state
so it can be used to guide future behavior. Although numerous studies
have investigated brain activity associated with spatial WM in humans
and monkeys, little research has focused on the neural mechanisms of WM
for temporal order information, and how processing of temporal and
spatial information might differ. Available evidence indicates that
similar frontoparietal regions are recruited during temporal and spatial
WM, although there are data suggesting that they are distinct processes.
The mechanisms that allow for differential maintenance of these two
types of information are unclear. One possibility is that neural
oscillations may differentially contribute to temporal and spatial WM.
In the present study, we used scalp electroencephalography (EEG) to
compare patterns of oscillatory activity during maintenance of spatial
and temporal information in WM. Time-frequency analysis of EEG data
revealed enhanced left frontal theta (5-8 Hz), enhanced posterior alpha
(9-12 Hz), and enhanced left posterior beta (14-28 Hz) power during the
delay period of correct temporal order trials compared to correct
spatial trials. In contrast, gamma (30-50 Hz) power at right lateral
frontal sites was increased during the delay period of spatial WM
trials, as compared to temporal WM trials. The present results are
consistent with the idea that neural oscillatory patterns provide
distinct mechanisms for the maintenance of temporal and spatial
information in WM. Specifically, theta oscillations are most critical
for the maintenance of temporal information in WM. Possible roles of
higher frequency oscillations in temporal and spatial memory are also
discussed. Published by Elsevier Ltd.


*Pages: 358-371 (Article)
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Temporal event structure and timing in schizophrenia: Preserved binding in a longer "now"

Martin, B; Giersch, A; Huron, C; van Wassenhove, V

*NEUROPSYCHOLOGIA*, 51 (2):358-371; SI JAN 2013

Patients with schizophrenia experience a loss of temporal continuity or
subjective fragmentation along the temporal dimension. Here, we develop
the hypothesis that impaired temporal awareness results from a perturbed
structuring of events in time-i.e., canonical neural dynamics. To
address this, 26 patients and their matched controls took part in two
psychophysical studies using desynchronized audiovisual speech. Two
tasks were used and compared: first, an identification task testing for
multisensory binding impairments in which participants reported what
they heard while looking at a speaker's face; in a second task, we
tested the perceived simultaneity of the same audiovisual speech
stimuli. In both tasks, we used McGurk fusion and combination that are
classic ecologically valid multisensory illusions. First, and contrary
to previous reports, our results show that patients do not significantly
differ from controls in their rate of illusory reports. Second, the
illusory reports of patients in the identification task were more
sensitive to audiovisual speech desynchronies than those of controls.
Third, and surprisingly, patients considered audiovisual speech to be
synchronized for longer delays than controls. As such, the temporal
tolerance profile observed in a temporal. judgement task was less of a
predictor for sensory binding in schizophrenia than for that obtained in
controls. We interpret our results as an impairment of temporal event
structuring in schizophrenia which does not specifically affect sensory
binding operations but rather, the explicit access to timing information
associated here with audiovisual speech processing. Our findings are
discussed in the context of curent neurophysiological frameworks for the
binding and the structuring of sensory events in time. (C) 2012 Elsevier
Ltd. All rights reserved.


*Pages: 372-376 (Article)
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Lengthened temporal integration in schizophrenia

Parsons, BD; Gandhi, S; Aurbach, EL; Williams, N; Williams, M; Wassef,
A; Eagleman, DM

*NEUROPSYCHOLOGIA*, 51 (2):372-376; SI JAN 2013

Research in schizophrenia has tended to emphasize deficits in higher
cognitive abilities, such as attention, memory, and executive function.
Here we provide evidence for dysfunction at a more fundamental level of
perceptual processing, temporal integration. On a measure of flicker
fusion, patients with schizophrenia exhibited significantly lower
thresholds than age and education matched healthy controls. We reasoned
that this finding could result from a longer window of temporal
integration or could reflect diminished repetition suppression: if every
frame of the repeating stimulus were represented as novel, its perceived
duration would be accordingly longer. To tease apart these non-exclusive
hypotheses, we asked patients to report the number of stimuli perceived
on the screen at once (numerosity) as they watched rapidly flashing
stimuli that were either repeated or novel. Patients reported
significantly higher numerosity than controls in all conditions, again
indicating a longer window of temporal integration in schizophrenia.
Further, patients showed the largest difference from controls in the
repeated condition, suggesting a possible effect of weaker repetition
suppression. Finally, we establish that our findings generalize to
several different classes of stimuli (letters, pictures, faces, words,
and pseudo-words), demonstrating a non-specific effect of a lengthened
window of integration. We conclude that the visual system in
schizophrenics integrates input over longer periods of time, and that
repetition suppression may also be deficient. We suggest that these
abnormalities in the processing of temporal information may underlie
higher-level deficits in schizophrenia and account for the disturbed
sense of continuity and fragmentation of events in time reported by
patients. (C) 2012 Elsevier Ltd. All rights reserved.


*Pages: 377-384 (Article)
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Time, action and psychosis: Using subjective time to investigate the effects of ketamine on sense of agency

Moore, JW; Cambridge, VC; Morgan, H; Giorlando, F; Adapa, R; Fletcher,

*NEUROPSYCHOLOGIA*, 51 (2):377-384; SI JAN 2013

Sense of agency refers to the experience of initiating and controlling
actions in order to influence events in the outside world. A disturbed
sense of agency is found in certain psychiatric and neurological
disorders, most notably schizophrenia. Sense of agency is associated
with a subjective compression of time: actions and their outcomes are
perceived as bound together in time. This is known as 'intentional
binding' and, in healthy adults, depends partly on advance prediction of
action outcomes. Notably, this predictive contribution is disrupted in
patients with schizophrenia. In the present study we aimed to
characterise the psychotomimetic effect of ketamine, a drug model for
psychosis, on the predictive contribution to intentional binding. It was
shown that ketamine produced a disruption that closely resembled
previous data from patients in the early, prodromal, stage of
schizophrenic illness. These results are discussed in terms of
established models of delusion formation in schizophrenia. The link
between time and agency, more generally, is also considered. (C) 2012
Elsevier Ltd. All rights reserved.

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