Biomedical subjects

E Pekkonen

Publications and source records attributed to E Pekkonen.

39 records · Page 3Linked to original sources

PubMedDate not supplied

Dose-related effect of alcohol on mismatch negativity and reaction time performance.

In a recent study, the mismatch negativity (MMN) component of auditory event-related potential, elicited by occasional frequency changes in a repetitive tone, was strongly attenuated by a low dosage of alcohol. We investigated the phenomenon in nine subjects with two different dosages of ethanol (0.35 and 0.55 g/kg), and with two magnitudes of frequency changes (5% and 10%), in a single-blind, placebo-controlled paradigm. Ethanol had no observable effect on the N1 and P2 deflections, nor on the reaction time to frequency changes measured in a separate session. However, the MMN was attenuated after administration of the larger dosage of alcohol, suggesting impaired preconscious processing of stimulus features outside the scope of attention. The results support the view according to which the automatic functions of human information processing are more sensitive than the controlled functions to the detrimental effects of alcohol. The fact that the MMN suppression was stronger when stimulus deviation was smaller indicates that at relatively low blood alcohol concentrations the detection of small deviations is especially hampered.

Acoustic Stimulation↗

PubMedDate not supplied

Aging effects on auditory processing: an event-related potential study.

Deviant tones randomly embedded in a sequence of standard tones elicit an event-related potential (ERP) called the mismatch negativity (MMN), which reflects automatic stimulus-change detection in the human auditory system. When the tones are attended, deviant tones elicit also an N2b component that partly overlaps the MMN. Sequences of standard and deviant (probability 0.15) tones were presented to 13 healthy younger and 13 older subjects. Deviant stimuli were, in separate blocks, either occasional shorter duration or higher frequency tones. The interstimulus interval (ISI) was, in separate blocks, either 0.5 s or 1.5 s, and in the frequency-change condition also 4.5 s. Aging affected neither frequency nor duration of MMN with the 0.5 s ISI. This finding indicates that automatic stimulus discrimination per se is not impaired with normal aging. However, with a 4.5-s ISI the MMN/N2b-complex attenuated significantly more in the older than younger subjects. This suggests that the stimulus trace decays faster or that involuntary attention switching is less sensitive with aging.

Acoustic Stimulation↗

PubMedDate not supplied

Mismatch negativity in aging and in Alzheimer's and Parkinson's diseases.

Mismatch negativity (MMN) is an auditory event-related potential (ERP) that reflects automatic stimulus discrimination in the human auditory system. By varying the interstimulus intervals (ISIs), the MMN can be used as an index of auditory sensory memory. This paper focuses on MMN findings in aging and in Alzheimer's (AD) and Parkinson's diseases (PD). The accumulated data suggest that MMN to duration deviance, unlike MMN to frequency deviance, is reduced in amplitude in aging at short ISIs. The attenuated MMN to frequency deviance observed at long ISIs in elderly subjects seems to be caused by age-related memory trace decay. Existing results suggest that automatic discrimination for the frequency change is not affected in the early phase of AD, whereas the memory trace seems to decay faster in AD patients. The present findings on PD are not as conclusive, although they tentatively suggest deteriorated automatic change detection. The MMN appears to offer an objective tool for studying auditory processing and memory trace decay in different neurological disorders.

Aged↗