Biomedical subjects

Thomas F Münte

Publications and source records attributed to Thomas F Münte.

57 records · Page 4Linked to original sources

PubMed2002

Implicit memory for words played during isoflurane- or propofol-based anesthesia: the lexical decision task.

BACKGROUND: Unconscious processing of words during general anesthesia has been suggested after surgery with several tests of implicit memory. Patients can neither recall those words nor do they have explicit memories of other intraoperative events. It is unclear to what degree information is processed during general anesthesia and which tests are best suited to detect implicit memory. In the current study, a lexical decision paradigm not previously used to demonstrate implicit memory during anesthesia was used. METHODS: Sixty patients undergoing lumbar disc surgery were assigned to receive isoflurane infusion- or propofol infusion-based anesthesia combined with alfentanil infusions and a nitrous oxide-oxygen mixture. A control group of 10 medical students listened to tapes without receiving anesthesia. Two tapes, each containing a list of 30 low-frequency German nouns repeated for 15 min, were prepared, with half of the patients listening to tape A and the other half listening to tape B during the operation. Exposure time was 15 min from the time of skin incision onward. In the test phase, approximately 7 h later, words from lists A and B plus 60 nonwords were presented in random order by a computer program. Subjects were asked to indicate, by pressing one of two response buttons, whether the spoken word was or was not a legal German word (lexical decision). RESULTS: A recognition test revealed chance recognition for words presented during anesthesia. Lexical decision responses, however, were slightly faster to primed (previously presented) words than to unprimed (not previously presented) words when the entire group of patients was tested, suggesting a small implicit memory effect, which barely failed to reach the significance level. When the two medication groups were tested separately, no significant implicit memory effect could be ascertained statistically. The effects of previous exposure were much more pronounced in the control group. CONCLUSIONS: Balanced anesthesia techniques with isoflurane or propofol lead to only a minimal, statistically borderline implicit memory effect in the lexical decision paradigm.

Acoustic Stimulation↗

PubMed2002

Influence of stimulus distance in implicit learning of spatial and nonspatial event sequences.

The serial reaction time task has been widely used to investigate implicit learning mechanisms. In the present study, we investigated the effect of stimulus distance on learning of a spatial sequence independent of a sequence of responses. Participants had to respond to objects appearing at four different locations. The objects were presented in a sequence of nine elements, whereas the location at which an object was presented followed a sequence of eight elements. Thus, the spatial and the object sequences were independent of each other. Four groups of subjects for whom the distances of the locations chosen to present objects on the computer screen (3 cm, 6 cm, 12 cm, or 22 cm) differed were tested. Only the nonspatial sequence was learned as indicated by enhanced response latencies in nonsequenced random blocks. Stimulus distance had no effect on the amount of sequence learning. Additional analyses for subgroups of subjects who did not show explicit knowledge of the sequences after completion of the task indicated that for implicit learners also, sequence learning was not influenced by stimulus distance. The results are discussed with respect to current theories of implicit serial learning.

Adolescent↗

PubMedDate not supplied

Cognitive brain potentials to novel acoustic stimuli in adult dyslexic readers.

Event-related brain potentials were recorded in two three-stimulus oddball tasks in 13 adult dyslexic and 13 age- and IQ-matched normal readers. The stimuli consisted of a random series of frequent (80%) and non-frequent tones (10%) as well as occasionally inserted novel sounds (10%). The experiment comprised an active (response to the rare target tone) and a passive listening condition. No performance differences were found for dyslexic and normal readers in the active task. In both conditions, novel sounds evoked a centrally distributed P3a-component followed by a P3b-component most prominent at parietal electrodes for target and novel sounds. Additionally, a slow negativity emerged after presentation of novel sounds at frontal electrodes. In the active condition only, peak amplitude of the P3a and the frontal slow negativity to novel stimuli were slightly enlarged for dyslexic readers. These findings indicate a larger distractability of dyslexic readers (enhancement of P3a to novel tones). Furthermore, we propose that dyslexics need to employ more cognitive resources to refocus on the task at hand (as indicated by the enlarged slow frontal negativity).

Acoustic Stimulation↗