Compared with many other cognitive functions, relatively little is known about time representation in the brain. Recent work shows disrupted timing and time estimation in older adults, although it is unclear whether these effects are the result of normal aging or disease-related processes. The present study examined time estimation in persons across the adult lifespan who were free from significant medical or psychiatric history. Results showed older adults exhibited greater variability in time estimation, but no evidence for systematic acceleration or slowing emerged. This variability was correlated with performance on a variety of cognitive tests including attention, working memory and executive function. Although no relationship emerged between time estimation and EEG indices from central regions, multiple MRI indices were significantly correlated with time estimation. Stepwise regression showed volume of the supplementary motor area predicted variability in time estimation. These results indicate that healthy aging is associated with altered time estimation and suggest that changes in frontal brain regions mediate these effects.
"It is thought that the ability to estimate the passage of time is related to cognitive processes and to the interaction between cognitive and biological mechanisms (Carrasco et al., 2000), whether in the framework of an internal clock (Dynamic Attending Theory; Scalar Expectancy Theory) or as time-dependent changes in the state of neural networks (Grondin, 2010). Memory processes, attention, frontal executive functioning, and perceiving number symbols seem to be important determinants (Chaston and Kingstone, 2004; Papagno et al., 2004; Gunstad et al., 2006; Cappelletti et al., 2009). As a cognitive estimation test, it would involve the activation of many complex cognitive functions including sets of semantic memories, retrieval of specific semantic memories, planning, working memory and mental control, self-monitoring, and self-correction (Bullard et al., 2004). "
[Show abstract][Hide abstract] ABSTRACT: Accuracy of estimation of time-intervals has received marginal attention in psychogeriatrics. We examined presumed differences in this time measure in participants with dementia (PWD) versus participants without dementia (PWoutD), further subdivided into specific diagnoses and performance subgroups. We also studied its demographic, clinical, and cognitive correlates and predictors. A diagnostic role was hypothesized.
Forty-three individuals (27 PWD: 16 dementia of the Alzheimer's type (DAT), 11 vascular dementia (VaD); 16 PWoutD: 10 major depressive disorder (MDD), 6 normal) were interviewed with the Cambridge Examination for Mental Disorders of the Elderly - Revised (CAMDEX-R) that permits the registration of this time measure. Demographic, clinical, and cognitive data were obtained.
Neither absolute accuracy of estimation of duration of interview nor its transformed logarithm were significantly different between PWD and PWoutD, or between DAT and VaD participants. MDD participants performed significantly poorer than normal and did not differ from PWD, and the PWD relatively better performing subgroup. The logarithm of absolute accuracy of estimation correlated with some clinical and cognitive variables. Only a measure of depression and of impaired judgment could significantly predict it.
The absolute accuracy of estimation of time-intervals did not differ between the major groups and the main diagnoses subgroups. It was associated with a variety of clinical and cognitive measures, and was predicted by the composite constructs of depression and impaired judgment. The diagnostic value of this measure in the psychogeriatric clinic is questionable, and limited to "worried" well individuals.
International Psychogeriatrics 01/2012; 24(5):809-21. DOI:10.1017/S1041610211002596 · 1.93 Impact Factor
"In patients with PD, intracortical inhibition at rest (Bares et al., 2003; Buhmann et al., 2004; Lewis and Byblow, 2002; MacKinnon et al., 2005; Pierantozzi et al., 2001; Ridding et al., 1995; Strafella et al., 2000) and movement-related activity of the SMA (Albin et al., 1989; Haslinger et al., 2001; Jahanshahi et al., 1995; Limousin et al., 1997; Playford et al., 1992; Rascol et al., 1992; Sabatini et al., 2000; Samuel et al., 1997) are decreased. In contrast to patients with PD, movementrelated activity in the SMA is increased in older adults relative to young adults (Gunstad et al., 2006; Hutchinson et al., 2002; Riecker et al., 2006; Sailer et al., 2000). It has been hypothesized that this increase in SMA activity may reflect a compensatory response associated with and an age-related decline in basal ganglia-thalamocortical function (De Keyser et al., 1990; Pugh et al., 2002; Reeves et al., 2002). "
[Show abstract][Hide abstract] ABSTRACT: In young healthy adults, syncopated finger movements (movements between consecutive beats) are characterized by a frequency-dependent change in phase at movement rates near 2 Hz. A similar frequency-dependent phase transition is observed during bimanual anti-phase (asymmetric) tasks in healthy young adults, but this transition frequency is significantly lowered in both patients with Parkinson's disease (PD) and older adults. To date, no study has examined the transition frequency associated with unimanual syncopated movements in patients with PD or older adults. This study examined the effects of movement frequency on the performance of unconstrained syncopated index finger flexion movements in patients with PD, older adult subjects matched to patients with PD, and young adult subjects. Syncopated movements were paced by an acoustic tone that increased in frequency from 1 to 3 Hz in 0.25 Hz increments. Movement phase was quantified and the movement frequency where subjects transitioned from syncopation to synchronization was compared between groups. The principal finding was a marked impairment in the ability of patients with PD to perform syncopated movements when off medication. Medication did not significantly improve performance. In addition, the transition frequency for older adult subjects was lower than young adult subjects. These findings demonstrate that, similar to bimanual tasks, the coordination dynamics associated with unimanual syncopated finger movements transition from a stable to an unstable pattern at significantly lower frequencies in patients with PD and older adults compared to young adults.
Brain research 08/2009; 1290:12-20. DOI:10.1016/j.brainres.2009.06.099 · 2.84 Impact Factor
"A decline in timing performance has been extensively reported in Parkinson's disease   . Fewer reports are present for patients with Huntington's disease    as well as for healthy older participants  . This declined timing performance in these groups is probably due to two reasons: (i) Fronto-striatal circuits are reduced in functioning in all these groups, relative to healthy young people. "
[Show abstract][Hide abstract] ABSTRACT: A decline in motor performance and timing performance is evident not only in clinical patient groups, e.g. with Parkinson's or Huntington's disease but also in normal ageing. Common to the mentioned groups is a deterioration in dopaminergic function of fronto-striatal brain circuits. These areas belong to a distributed network in the brain playing an important role in time perception and timing behaviour. Therefore, we measured time estimation performance in five groups of healthy young and healthy old participants, of patients with Parkinson's disease (PD), with presymptomatic and symptomatic Huntington's disease (HD). Participants were instructed to indicate by a precise button press when 1.2s had elapsed after stimulus onset. They received feedback after correct (within a specified time window) or incorrect responses. When compared to the young control group the performance in old participants, patients with Parkinson's, presymptomatic and symptomatic Huntington's disease was inferior, while differences were not noticed between the latter four groups. The data underline the importance of fronto-striatal circuits in the brain for time processing and time estimation. It is suggested that it is not the degree of dysfunction of the fronto-striatal dopamine system but rather the mere existence of a dysfunction, even if subtle, which is pivotal for a decline in timing performance. A time estimation task can serve as a useful tool to detect even faint changes in the integrity of the fronto-striatal dopamine system.
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