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Biomedical subjects

M Kutas

Publications and source records attributed to M Kutas.

At least 91 records · Page 5Linked to original sources
PubMed1980

Preparation to respond as manifested by movement-related brain potentials.

Ten subjects were instructed to squeeze a dynamometer in a prescribed manner in order to assess the effects of motor preparation on event-preceding brain potentials. Right and left hand responses were required in 5 different experimental conditions allowing different degrees of advance preparation. Six channels of EEG (F3, F4, C3', C4', P3, P4) and two channels of EMG were digitized over a 3000 msec epoch, and response-locked averages were computed. Event-preceding negative potentials were evident well in advance of movement if the subject was informed of the timing of the response. These premovement potentials were asymmetrical on the scalp (contralaterally dominant at the central sites) if the subject knew which hand would be required to respond. Thus, we conclude that the appearance and asymmetry of these potentials reflect preparation to execute specific motor acts.

Cerebral Cortex↗
PubMed1980

Reading senseless sentences: brain potentials reflect semantic incongruity.

In a sentence reading task, words that occurred out of context were associated with specific types of event-related brain potentials. Words that were physically aberrant (larger than normal) elecited a late positive series of potentials, whereas semantically inappropriate words elicited a late negative wave (N400). The N400 wave may be an electrophysiological sign of the "reprocessing" of semantically anomalous information.

Brain↗
PubMed1980

Event-related brain potentials to semantically inappropriate and surprisingly large words.

Event-related brain potentials (ERPs) were recorded from young adult subjects as they silently read 160 different seven-word sentences, presented one work at a time. The sentences either ended normally or were completed by unexpected words that were either semantically inappropriate, physically deviant or both. These two types of deviations were associated with distinctly different ERP components - a late negative wave (N400) for semantic deviations and a late positive complex for physical deviations. A deviation along either one or these dimensions (semantic or physical) did not appear to alter the ERP effect of a concurrent deviation along the other. In addition, it was found that the ERPs elicited by the words during the reading condition were characterized by a left-greater-than-right asymmetry in a slow, positive component. This asymmetrical scalp distribution was most pronounced for right-handed subjects having not left-handers in their immediate family.

Adult↗
PubMed1977

Augmenting mental chronometry: the P300 as a measure of stimulus evaluation time.

A technique for measuring the latency of the P300 component of event-related brain potentials on individual trials is described. Choice reaction times and the latency of the P300 were compared under speed-maximizing and under accuracy-mazimising instructions. The choice stimuli required different levels of semantic categorization. The data support the proposition that the latency of P300 corresponds to stimulus evaluation time and is independent of response selection.

Brain↗
PubMed1975

On the independence of the CNV and the P300 components of the human averaged evoked potential.

We report an experiment designed to assess the interactions between the CNV and the P300 components of human event-related potential. Eight subjects were each presented with series of experimental trials on all of which either a 1200 c/sec or an 800 c/sec tone was presented. There were three independent variables: (a) The presence or absence of a warning flash 1000 msec prior to the tone. (b) The task assigned to the subject--that is subjects were either to make a discriminative response to the tone or, on half the series, to predict prior to the tiral which of the two tones would be presented. (c) The predictability of the tone frequency. On half the series high and low tones alternated from trial to trial. On the other series, tones were chosen randomly on each trial. The data show that the amplitude of the P300 component is not affected by the presence or absence of a warning stimulus. Furthermore, the distributions of P300 and the CNV over the scalp are quite different. These conclusions are supported by a principal component and a discriminant analysis of the data. We conclude that the CNV and the P300 reflect the activity of functionally distinct cortical mechanisms.

Analysis of Variance↗
PubMed1975

Changes in plasma thyroxine, triiodothyronine, and TSH during adaptation to iodine deficiency in the rat.

We have measured plasma thyroxine (T4), triiodothyronine (T3), and TSH with specific radioimmunoassays in rats during adaptation to severe iodine deficiency after they had previously received regimens supplying various quantities of iodine. Rats were maintained on a high-iodine diet (HID) containing 3 mg iodine/kg or a low-iodine diet (LID) containing 30 mug iodine/kg supplemented with 0.1, 0.2, or 0.4 mug iodine/ml of drinking water before swtiching to KID alone. Frequent serial blood samples were obtained up to 3 months, using 6 or more animals for each time interval. In animals originally fed HID, T4 remained at 4-6 mug/100 ml unitl the tenth day of LID, then rapidly decreased to a value of less than 0.4 mug/100 ml at 1 month. TSH was initially 50 muU/ml and increased linearly to 165 muU/ml on day 16. Thence there was a much more rapid rate of rise to 640 muU/ml at 38 days. The rats changed to LID alone after having been fed LID with iodine supplementation underwent similar qualitative hormonal changes. However, the decrease in plasma T4 and the increase in plasma TSH occurred sooner in the rats which had drunk water containing only 0.1 or 0.2 mug iodine/ml than in the previous experiment. Rats which had received 0.4 mug iodine/ml showed a pattern essentially identical to that of the animals which had been fed HID. plasma T3 did not change significantly in any of the experiments, remaining at 60-90 ng/100 ml, although there was a tendency for the values to be somewhat lower after several weeks of LID. There was a highly significant negative correlation of plasma T4 with plasma TSH. There was no significant correlation of plasma T3 with either plasma T4 or plasma TSH. It is concluded that the combined physiologic effect of plasma T4 and T3 concentration is more important in determining TSH secretion through negative feedback effects on the hypothalamus and/or pituitary than is the concentration of plasma T3.

Animals↗
PubMed1974

Studies of squeezing: handedness, responding hand, response force, and asymmetry of readiness potential.

Eleven subjects squeezed an electronic dynamometer, at each of three force levels, with both their right and left hands. In right-handed subjects the premovement "readiness" potentials were larger over the hemisphere contralateral to the responding hand. Left-handed subjects show contralateral dominance when responding with the right hand but not when responding with the left hand. The data suggest that in the potentials studied there is a component associated with the preparation to perform a specific movement, rather than with generalized preparatory processes.

Action Potentials↗