Abstract
The capacity to pay attention is important for the cognitive ability, for example, evaluating an object for its qualities. Attention can selectively prioritize the neural processes that are relevant to a given task. Neuroimaging investigations on human attention are primarily focused on vision to the exclusion of other sensory systems, particularly olfaction. Neural underpinnings of human olfactory attention are still not clearly understood. Here, we combined electroencephalographic measurements of olfactory event related potential with electrical neuroimaging to investigate how the neural responses after inhaling the same odor differ between conditions with varying levels of attention, and, in which brain areas. We examined the neural responses when participants attended to a rose-like odor of phenylethyl alcohol for evaluating its pleasantness versus its passive inhalation. Our results gathered significant evidence for attentional modulation of the olfactory neural response. The most prominent effect was found for the late positive component, P3, of olfactory event related potential within a second from the odor onset. The source reconstruction of this data revealed activations in a distributed network of brain regions predominantly in inferior frontal cortex, insula, and inferior temporal gyrus. These results suggest that the neuronal modulations from attention to olfactory pleasantness may be subserved by this network.
Highlights
Attention is the ability to choose and concentrate on relevant stimuli, and has been a topic of active research interest among neuroscientists
The average olfactory event related potential (OERP) amplitudes corresponding to N1, P2 and P3 components for these conditions are plotted in a topographic map (Fig. 3)
We examined olfactory attention by contrasting OERP data of attend (AT) with that of not-attend (NA) trials given an identical stimulus, PEA
Summary
Attention is the ability to choose and concentrate on relevant stimuli, and has been a topic of active research interest among neuroscientists. Attending to an odor for evaluating its intensity can evoke a faster response time relative to when attention is directed elsewhere[3] Such task-related top-down control of attention is known to enhance neural activity in the brain areas that underlie neural processing of the attended stimulus. Previous olfactory event related potential (OERP) studies have shown that attending to the olfactory stimulus for its active evaluation, e.g., in an intensity judgement or detection task, results in greater amplitude of its later peak, P3, when compared to its passive inhalation in a non-olfactory task or a relax condition[4,5,6,7]. A PET study reported increased activation in orbitofrontal cortex during both pleasantness and intensity evaluation tasks when compared with passive no-odor task[17]. More precise information on the time course of neural activity is provided by event related potentials (ERPs) measured with Electroencephalography (EEG)
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