The research interests of our laboratory include the behavioral, pharmacological, and electrophysiological basis of timing and time perception in the seconds-to-minutes range. We all have a sense of time. Yet there are no sensory receptors specifically dedicated for perceiving time. It is an almost uniquely intangible sensation: we cannot see time in the way that we see colour, shape or even location. So how is time represented in the brain? We explore the neural substrates of metrical representations of time such as duration estimation (explicit timing) or temporal expectation (implicit timing). Basal ganglia, supplementary motor area, cerebellum and prefrontal cortex have all been linked to the explicit estimation of duration. However, each region may play a functionally discrete role and will be differentially implicated depending upon task context. Among these, the dorsal striatum of the basal ganglia and, more specifically, its ascending nigrostriatal dopaminergic pathway appears to be the most crucial of these regions, as demonstrated by converging functional neuroimaging, neuropsychological, and psychopharmacological investigations in humans, as well as lesion and pharmacological studies in animals. Moreover, neuronal firing rates in both striatal and interconnected frontal areas vary as a function of duration, suggesting a neurophysiological mechanism for the representation of time in the brain, with the excitatory-inhibitory balance of interactions among distinct sub-types of striatal neuron serving to fine-tune temporal accuracy and precision.
Other work focuses on developmental periods of choline sensitivity that provide an ontogenetic mechanism for regulating memory capacity and age-related dementia in humans and other animals. The ability to remember and use information accurately is very important in everyday life, and age-related memory impairments can have a profoundly negative impact on an individual’s life. These observations motivate research to understand the brain mechanisms involved in normal memory function, and the types of lifespan-developmental changes that produce dysfunctions in memory consolidation. At the same time it is of critical importance to understand the early developmental stages that brain and behavior processes transition through in terms of defining cognitive function in later life. Previous research has demonstrated that modification of the hippocampus and frontal cortex produce behavioral changes that have some of the basic characteristics of an amnesic syndrome with associated dysfunctions in executive processes. As a consequence, the main goal of the current proposal is to extend our recent findings showing that modifications in prenatal choline availability (e.g., deficiency, sufficiency, and supplementation) systematically alters the power and frequency of oscillatory patterns of neural activity in the hippocampus and cortex that are associated with memory consolidation during REM sleep states. These changes in the power and frequency of gamma (30-100 Hz) and sharp-wave ripple oscillations (100-250 Hz) will be studied with respect to a) the time course for the transfer of contextual information from the hippocampus to the prefrontal cortex, b) age-related changes in the susceptibility to memory impairments associated with sleep deprivation, c) induced increases or decreases in hippocampal neurogenesis, and d) metabolomic and transgenerational effects in 4 mo, 14 mo, and 24+ mo rats.
Joos van Craesbeeck - Temptation of St Anthony (1650)
Francoise POUTHAS - Time's Arrow Scientific American - Special Edition
A Matter of Time (2002 & 2006).
UNDER CONSTRUCTION - 3/15/10
UNDER CONSTRUCTION - 3/15/10