Neuropharmacology of visual attention
Although major advances have been made in understanding the neuronal bases of sensory-guided behaviour over the last 30 years many important aspects of sensory perception remain still to be uncovered.
Sensory guided behaviour (and memory formation) require voluntary attention. The word 'attention' is ubiquitously used in everyday parlance, but what exactly it means in terms of brain function remains relatively unclear. So far it has been demonstrated that attention helps to process certain stimuli in the external world more efficiently, i.e. neurons that code for the presence of an attended object increase their activity ('they make themselves better heard'). While these results shed light on 'what' attention does to neural processing, it is unresolved 'how' attention influences sensory processing. The research aims to determine how attention affects neuronal processing and which chemical systems are involved in these mechanisms. The results will provide definite answers to the role of neuromodulators in mediating effects of attention. Moreover they have important implications for our understanding and treatment of various disorders related to the functioning of the neuromodulatory systems (e.g. Alzheimer disease, Lewy Body dementia, Attention Deficit Hyperactivity Disorder, Parkinson disease, Depression, Schizophrenia).
The work in my laboratory studies the effects of attention on response specificity in sensory processing, and the underlying mechanisms mediating the activity changes associated with selective attention. The aim of these studies is to determine rigorously the anatomical networks and neurochemical mechanisms of attention and attentional selection.
In particular the following questions are addressed:
~ The role of neuromodulators on sensory processing and
neuronal gain modulation.
~The effects of neuromodulators on sensory processing and their
interaction with selective spatial attention.
~The location of the sources of selective spatial attention, and the
mechanisms by which attentional modulation of sensory
processing is redistributed to early sensory areas.
~The effects of attention on sensory filter functions and how it
affects spatial and temporal stimulus integration across the
whole visual field in simple as well as in rich/naturalistic
~The effects of neuromodulators on changing the synaptic efficacy
of the different cortical network components and their
implications on cortical computing.
~The effects of motivation, predictability, and reward likelihood on
the allocation of attention, and their effect on neuromodulator release.
Over the last few years we have made important progress towards answering some of these questions, but our results have equally highlighted the difficulties involved in untangling the contributions of different receptors to cognitive functions in different areas.