Paradoxical Effects of Gp Dbs on Distorted Temporal Memory in PD

The STn DBS work was followed up with pallidal DBS (Benabid et al., 1991 Filion et al., 1991 Tronnier et al., 1997). Given the sophisticated DBS technique used by our collaborators, we were fortunate to identify distinct effects related to the altered neural activity in either the globus pallidus external capsule (GPe) or globus pallidus internal capsule (GPi) portions of the globus pallidus in PD, as compared to STn DBS. Details on the technique and clinical electrophysiological and anatomical...

Interval timing and other areas of Cognitive Aging

Most of this chapter has focused on the ways in which age differences in attention affect older adults' interval timing performance relative to that of young adults, but interval timing research can also be useful for gaining a broader understanding of the cognitive changes that occur with advanced age. On a procedural level, the nonverbal and continuous nature of many interval timing tasks minimizes the con-founders that can be problematic for aging studies of attention and memory. In...

Interval Timing Sensitivity in Persons at Risk for Schizophrenia

Given the findings of different sensitivities to modality effects in young and aged populations, it is worthwhile to consider whether the existence of modality effects may prove a useful tool for examining the cognitive and neurophysiological bases of timing via studies of patient populations. For example, a number of studies have reported temporal processing deficits in patients diagnosed with schizophrenia (Sz). Overestimation of duration in the seconds range has been reported for verbal...

Summary And Conclusions

This chapter presents an extensive, although nonexhaustive, survey of the effects of auditory and visual signal modality on interval timing. It is clear from the literature described here that the modality of a timing signal can have a significant influence on the discriminability of a timing signal, its subjective duration, or both. It is also clear that visual-auditory modality effects on timing take at least two forms. In some cases, the magnitude of the modality effect is an absolute...

The Persistence of Time

Humans and other animals engage in a startlingly diverse array of behaviors that depend critically on the time of day or the ability to time short intervals. Timing intervals on the scale of many hours to around a day are mediated by the circadian timing system, while in the range of seconds to minutes a different system, known as interval timing, is used. Nonlinearities in the sensitivity to time as well as a dependence on the normal functioning of the suprachiasmatic region of the...

Neural Basis Of Interval Timing

A rich tradition of normative psychophysics has identified two ubiquitous properties of interval timing the scalar property, a strong form of Weber's law, and ratio comparison mechanisms (Gallistel and Gibbon, 2001 Gibbon, 1977). Temperature and reinforcement density effects on the speed of the internal clock have also been studied in order to determine mechanisms of compensation and regulation (see Hills, this volume). Isolating the neural substrate of these properties is a major challenge for...

Differentiating The Models

6.7.1 Are Animals and Infants Merely Subitizing When adult humans name the number of elements in a visual display, the slope in the function relating reaction time to numerosity is approximately 57 msec per item for values 1 to 4 and 300 msec per item for values 5 to 20 (Klahr, 1973). This apparent elbow in the slope of the reaction time function for labeling the number of items in visual displays is typically offered as evidence that two distinct processes are engaged for small and large...

Dopamine And The Internal Clock

12.2.1 An Information-Processing Model of Interval Timing A representation of the mapping between the stopwatch metaphor (Church, 1978) and an information-processing model of interval timing (Gibbon et al., 1984) is given in Figure 12.1A. The information-processing model of interval timing continues the tradition of Treisman's (1963) internal clock in that pulses emitted by a pacemaker are temporarily stored in an accumulator, and that upon delivery of reinforcement, the number of pulses from...

Dopamine And Interval Timing

Over the last two decades, advances have been made in specifying brain systems involved in temporal processing, and links have been established between cognitive processes underlying timing and particular pharmacological and physiological manipulations (Gibbon et al., 1997 Ivry, 1996 Rao et al., 2001). Extensive animal work has described the role of dopaminergic brain systems and the striato-frontal circuitry in timing behavior. Specifically, the output dopaminergic neurons originating in the...

Temporal Memory And The Basal Ganglia

We followed up the memory failure hypothesis by investigating whether the deficits of PD patients result from dysfunction in either storing (writing to) or retrieving (reading from) temporal memory. PD patients were tested with a new design that withheld feedback on the second day of testing. Performance on the second day was therefore based solely on the retrieval of the information learned during the previous day. We used the standard PI timing procedure on the first day (the training session...

Origin of STn Overactivity in PD

The STn plays a key role in the basal ganglia circuitry, and its hyperactivity may be a major factor in parkinsonian symptomatology (Marsden and Obeso, 1994). According to the classical PD model, it is the hypoactivity of the GPe that leads to increased STn activity, which in turn (in addition to the diminished influence of the direct striatal GABAergic input) induces the pathological overactivity of GPi (Figure 20.6). However, although stimulation of the STn induces a strong activation of GPe...

Cnv Topography And Generators

Stimulus Preceding Negativity

The primary source of evoked potentials is neuronal activity in the upper layers of the cortex. It is primarily the simultaneous occurrence of numerous excitatory postsynaptic potentials at apical dentrites of pyramidal neurons close to the recording electrode that causes changes in the evoked potentials at the surface of the head (Birbaumer et al., 1990). Most studies report that the CNV is mainly observed at fronto-central, central, and centro-parietal regions. However, it is sometimes...

The Importance Of Interval Timing In Memory And Attention

Human learning and memory is also highly sensitive to temporal factors, and oscillator-based models have been proposed for the coding of serial order in memory (e.g., Brown and Chater, 2001 Brown et al., 2000 McCormack and Hoerl, 2001). In addition, deficits in learning, memory, set shifting, and interval timing have been observed in a variety of patient populations with damage to the basal ganglia, including Parkinson's disease and Huntington's disease patients, as well as other cortical and...

Functional Anatomy Account A Revised Model Of The Basal Ganglia

Overactivity of the STn is seen by the classical PD model as a key abnormality underlying parkinsonian symptoms in human and nonhuman primates (Albin et al., 1989 DeLong, 1990). However, the evidence not only remains controversial, but also is for the most part restricted in motor deficits. A cartoon illustration of this model is shown in Figure 20.6. Like any model, the classical Albin-DeLong model of the basal ganglia is limited, because it is trying to simplify the complex reality (Chesselet...

Scalar Timing Theory

Scalar timing theory (see Church, this volume Gibbon et al., 1984) is an information-processing account of interval timing that grew out of scalar expectancy theory (SET) (Gibbon, 1977). All models of interval timing require three basic functions a clock function that measures elapsed time by converting it to some physical representation, a memory function in which a recorded time interval can be represented and stored, and a decision function that uses output from the clock and the memory...

Age Differences in Attention Relevant to Interval Timing

Attention plays an important role in interval timing performance, but as described above, timing can also be affected by influences on memory, the pacemaker, or other components of the information-processing model. Furthermore, the term attention is a broad one and has been operationalized in many procedures that have no apparent relation to one another. Not every cognitive function that falls under the rubric of attention will have an influence on interval timing see discussion by Meck and...

Mechanisms Underlying Modality Effects In Time Perception

Pacemaker Switch Accumulator System

The following section outlines some of the evidence suggesting that there are latency differences in signal detection or differences in clock speed between the visual and auditory modalities. As noted above, both timing onset-offset latency and clock speed have been proposed as putative mechanisms underlying modality differences. Evidence that the response time RT for an auditory stimulus is shorter than that for a visual stimulus, by about 40 msec, comes from experiments showing that in order...

References

Abner, R.T., Edwards, T., Douglas, A., and Brunner, D., Pharmacology of temporal cognition in two mouse strains, Int. J. Comp. Psychol., 14, 189-210, 2001. Allada, R., Emery, P., Takahashi, J., and Rosbash, M., Stopping time the genetics of fly and mouse circadian clocks, Annu. Rev. Neurosci, 24, 1091-1119, 2001. Allan, L.G., The influence of the scalar timing model on human timing research, Behav. Process, 44, 101-117, 1998. Allers, K.A., Ruskin, D.N., Bergstrom, D.A., Freeman, L.E., Ghazi,...

An Information Processing Metaphor of Scalar Timing Theory

Scalar Timing Theory

The model consists of three processes perception, memory, and decision as illustrated in Figure 1.1 . Perception of time consists of a pacemaker, a switch, and an accumulator. The pacemaker emits pulses according to some simple distribution. If a switch is closed, these pulses enter the accumulator, which can be reset by another switch. When reinforcement occurs, the number of pulses in the accumulator transformed by a multiplicative constant is stored in memory. Thus, memory consists of an...

Connections Between Interval Timing Neuropharmacology And Drug Abuse

Drugs that increase the effective level of dopamine in the brain, such as cocaine and methamphetamine, are among the most commonly abused drugs today Stahl, 2000 . The connection between interval timing and drug abuse comes from the fact that dopaminergic drugs cause predictable distortions in timing and time perception. The dopamine agonist, methamphetamine, causes a leftward shift in psychophysical timing functions that is proportional in size to the duration of the interval being timed e.g.,...