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...

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.,...