Biomedical subjects

Piia Astikainen

Publications and source records attributed to Piia Astikainen.

4 recordsLinked to original sources

PubMed2006

Memory-based detection of rare sound feature combinations in anesthetized rats.

It is unclear whether the ability of the brain to discriminate rare from frequently repeated combinations of sound features is limited to the normal sleep/wake cycle. We recorded epidural auditory event-related potentials in urethane-anesthetized rats presented with rare tones ('deviants') interspersed with frequently repeated ones ('standards'). Deviants differed from standards either in frequency alone or in frequency combined with intensity. In both cases, deviants elicited event-related potentials exceeding in amplitude event-related potentials to standards between 76 and 108 ms from the stimulus onset, suggesting the independence of the underlying integrative and memory-based change detection mechanisms of the brain from the normal sleep/wake cycle. The relations of these event-related potentials to mismatch negativity and N1 in humans are addressed.

Acoustic Stimulation↗

PubMed2006

Proactive interference in a two-tone pitch-comparison task without additional interfering tones.

Two-tone pitch-comparison tasks typically comprise several successive pairs of successive tones separated by silent intervals. The serial occurrence of such pairs has been associated with degraded task performance, but the nature of this association is not fully understood. Human adult participants were presented with successive pairs of successive tones. The latter, to-be-compared tone of a pair could differ from the former, to-be-remembered tone of 1046.5 Hz by no more than +/-15 Hz (25 cents). The direction of this difference was easier to identify when it was opposite to that of the preceding pair than when being the same. Merely responding accordingly (irrespectively of whether the response was correct or not) was found not to account for this finding. Our study demonstrates proactive interference in a two-tone pitch comparison task as the difficulty to remember when the first tone of the present pair occurred relative to the last tone of the immediately preceding pair.

Acoustic Stimulation↗

PubMed2004

The human brain processes visual changes that are not cued by attended auditory stimulation.

Event-related potentials (ERPs) to visual stimuli were recorded from the scalp of eight adult humans performing a task in which they counted vowels from a heard story. In the oddball condition, a repeated (standard) light bar of 50 ms in duration was rarely (P = 0.1) replaced by a (deviant) one differing in orientation from the standard. In the control condition, standards were simply omitted from the series and only (alone-) deviants retained. In both conditions, visual stimuli were asynchronous with auditory-task-relevant stimuli. ERPs to deviants significantly differed in amplitude from those to standards in the midline electrodes centrally, parietally and occipitally at 160-200 ms from stimulus onset. Occipitally, such a difference was absent between ERPs to alone-deviants and those to standards. The occipital differential ERPs to deviants, which thus could be found only when standards were present in the series, are discussed in the context of the mismatch negativity (MMN).

Acoustic Stimulation↗

PubMed2004

Longer storage of auditory than of visual information in the rabbit brain: evidence from dorsal hippocampal electrophysiology.

Whereas sensory memory in humans has been found to store auditory information for a longer time than visual information, it is unclear whether this is the case also in other species. We recorded hippocampal event-related potentials (ERPs) in awake rabbits exposed to occasional changes in a repeated 50-ms acoustic (1000 versus 2000 Hz) and visual (vertical versus horizontal orientation) stimulus. Three intervals (500, 1500, or 3000 ms) between stimulus repetitions were applied. Whereas acoustic changes significantly affected ERPs with the repetition intervals of 500 and 1500 ms, visual changes did so only with the repetition interval of 500 ms. Our finding, thus, suggests a similarity in sensory processing abilities between human and non-human mammals.

Acoustic Stimulation↗