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Biomedical subjects

S Mäntysalo

Publications and source records attributed to S Mäntysalo.

11 recordsLinked to original sources
PubMed1988

Hippocampal rhythmic slow activity in rat lines selected for differences in ethanol-induced motor impairment.

Hippocampal rhythmic slow activity (RSA) was recorded during rotation and vibration stimulation after saline and ethanol (2 g/kg) administration in restrained alcohol-sensitive (ANT) and alcohol-insensitive (AT) rats implanted with chronic bipolar electrodes in the dorsal hippocampus. The saline-treated ANT rats had more high-frequency RSA than the AT rats, especially during the rotational stimulation of the optovestibular mechanisms. The difference was not found during ethanol sessions. Plasma corticosterone levels were significantly higher in the AT than the ANT rats after the recording sessions. This first electrophysiological demonstration of an alcohol-sensitivity difference in the brain between these rat lines is discussed in relation to behavioral tilting plane test used in the development of the lines, to the different innate responses of the lines to acute stress, and to the plausible line differences in brain GABAergic and serotonergic mechanisms that are known to modulate hippocampal EEG in rodents.

Animals↗
PubMed1987

The duration of a neuronal trace of an auditory stimulus as indicated by event-related potentials.

Event-related brain potential studies have revealed a component called the mismatch negativity (MMN) in response to occasional deviant stimuli presented in a sequence of homogeneous repetitive, 'standard', stimuli. This negativity probably reflects an automatic neuronal-mismatch process with a neuronal representation of the standard stimulus. The present study aimed at determining the duration of the assumed neuronal representation by varying the inter-stimulus interval (ISI) of a stimulus block. It was assumed that a deviant stimulus can elicit a MMN only when the neuronal representation of the previous standard stimulus still exists. It was found that a clear MMN was elicited by the deviant stimulus when the ISI was 1 or 2 s, but not when the ISI was 4 or 8 s. This suggests that the duration of the neuronal representation involved was less than 4 s.

Adult↗
PubMed1987

Ethanol-induced modulation of hippocampal EEG and cerebral 2-deoxyglucose accumulation in rat lines with differing alcohol sensitivities.

Rat lines (AT, alcohol tolerant, insensitive; ANT, alcohol nontolerant, sensitive) selectively bred for differences in ethanol-induced motor impairment were subjected to studies on neuronal signal processing and cerebral regional glucose uptake as influenced by an acute moderate dose (2 g/kg) of ethanol. The cerebellar membrane GABA receptor complex was also studied with binding experiments using naive AT and ANT rats. Recordings of hippocampal EEG indicated that with and without ethanol administration a rotational stimulus caused EEG synchronization in both rat lines. There was no major difference in the 2-deoxyglucose accumulation into gross brain regions between the lines. Thus, a moderate dose of ethanol does not make these rat lines distinguishable in these tests. The number of muscimol binding sites tended to be higher and that of flunitrazepam binding sites lower in the cerebellum of AT rats. These variations could not be abolished by treating the membranes with a detergent to remove possible endogenous substances bound to the receptors. The functional significance of this small difference is not known, as the relationship between receptor numbers and function is still vague. The present results indicate that the central nervous system factors involved in acute alcohol sensitivity are subtle requiring detailed study at all levels from the membrane molecules to behaving animals.

Alcoholism↗
PubMed1986

Event-related potentials (ERPs) in a learning and memory test.

The present study outlines a new paradigm to investigate the effects of learning and memory on event-related potentials (ERPs). In the learning phase, subjects had to learn a sequence of 12 auditory consonant-vowel syllables. In the test phase, subjects had to detect and report a change in the learned sequence. Auditory ERPs were recorded from the frontal, vertex, and parietal midline positions. In the learning phase, an early negative effect (EN) and a P3 with a slow wave (SW) occurred for the learned syllables, whereas a pre-stimulus negativity (PSN) occurred prior to the syllables not yet learned. In the test phase, the PSN preceded both the replaced syllables and those presented in their old positions. The EN and an N2-P3 complex were elicited by the replaced syllables, the EN by the syllables presented in their old positions. It was concluded that the ERPs can display specific effects related to cognitive processes underlying learning and memory. The PSN was suggested to reflect the expectation of the stimuli, the EN the activation of a template and the rehearsal of the stimuli. The SW was suggested to be related to a template match process with the learned syllables. The N2, elicited by the replaced stimuli, could imply a cognitive template mismatch and the P3 with the SW the updating of working memory.

Adult↗
PubMed1984

Effects of impulse noise and continuous steady state noise on hearing.

In this study the effects on hearing induced by occupational exposure to impulse noise were compared with those induced by exposure to continuous steady state noise. Three groups exposed to impulse noise, one group exposed to continuous steady state noise, and an unexposed control group were studied. The hearing thresholds of the groups were measured by a puretone audiometer three times in two workdays. None of the groups showed significant differences between the hearing thresholds measured in the morning, at midday, and in the afternoon. Group 1 with the shortest duration of exposure and group 2 with the intermediate duration of exposure to impulse noise had the highest thresholds at 6000 Hz in both ears. Group 3 with the longest duration of exposure to impulse noise had the highest thresholds asymmetrically, at 4000 Hz in the left ear and at 6000 Hz in the right ear. The group exposed to continuous steady state noise also had the highest thresholds asymmetrically, in the left ear at 6000 Hz. It was concluded that the longer the duration of exposure to impulse noise the wider the region of the frequencies that showed raised threshold shifts in both ears. Impulse noise seemed to produce permanent threshold shifts at 4000 and 6000 Hz after a shorter duration of exposure than continuous steady state noise.

Adult↗