Sensitivity of functional tympanic membrane thermometry (fTMT) as an index of hemispheric activation in cognition.

The measure of hemispheric activation in cognitive and clinical studies remains out of reach of many scientists due to cost, analysis complexity, and practical consideration of the techniques available such as fMRI, EEG, or EMG. The present study was conducted to determine whether infrared functional tympanic membrane thermometry (fTMT) is a measure of lateralised activation sensitive enough to be used in typical cognitive and clinical experiments. A total of 24 participants had their tympanic membrane temperature measured while performing a letter-matching task.

Hemispheric interactions are different in left-handed individuals.

In a previous study, N. Cherbuin and C. Brinkman (2006) showed that in right-handed participants, interhemispheric transfer time (measured with A.

Do synaesthetic colours act as unique features in visual search?

For individuals with grapheme-colour synaesthesia, letters, numbers and words elicit vivid and highly consistent colour experiences. A critical question in determining the mechanisms underlying the phenomenon is whether synaesthetic colours arise early in visual processing, prior to the allocation of focused attention, or at some later stage following explicit recognition of the inducing form. If the synaesthetic colour elicited by an achromatic target emerges early in visual processing, then the target should be relatively easy to find in an array of achromatic distractor items, provided the target and distractors elicit different synaesthetic colours.

Efficiency of callosal transfer and hemispheric interaction.

The corpus callosum (CC) is essential to hemispheric interaction, but it is unclear how individual callosal properties affect interaction between the cerebral hemispheres. A number of studies have demonstrated some relationship between morphology or structure of the CC and measures of hemispheric interaction. However, to the authors' knowledge, none of these studies has been able to show a clear, direct relationship between a behavioral measure of transfer speed through the CC, interhemispheric transfer time (IHTT), and a behavioral measure of hemispheric interaction.

Hemispheric activation and interaction: past activity affects future performance.

Previous studies have shown that when hemispheric activation is modulated by a lateralised task performed concurrently with a second task, performance in the second task is affected by the side of the more active hemisphere. This effect is thought to be produced by competition for limited resources required to complete the two tasks and/or by a greater allocation of attention to the hemifield contralateral to the more active hemisphere. Little is known on how task performance is affected by the pattern of activation in the two cerebral hemispheres before a target task is conducted.

Practice makes two hemispheres almost perfect.

Some tasks produce a performance advantage for conditions that require the processing of stimuli in two visual fields compared to conditions where single hemifield processing is sufficient. This advantage, however, disappears with practice. Although no definitive evidence yet exists, there are several possible mechanisms that might lead to improved performance of within- compared to across-hemisphere processing with practice.

Cognition is cool: Can hemispheric activation be assessed by tympanic membrane thermometry?

Hemispheric activation during cognitive tasks using functional magnetic resonance imaging (fMRI) can be difficult to interpret, uncomfortable, and is not widely available. This study investigated whether tympanic membrane thermometry could be used as a broad measure of hemispheric activation. Infrared probes measured ear temperature continuously while subjects performed left or right hemisphere tasks.