Biomedical subjects

Peter Brugger

Publications and source records attributed to Peter Brugger.

4 recordsLinked to original sources

PubMed2003

Human locomotion: levodopa keeps you straight.

Locomotion depends on an intact dopamine system. This system seems to be functionally asymmetric, as evidenced by an asymmetric turning preference. Using a double-blind procedure, the effect of levodopa on the number of veers when walking blindfolded along a straight line (20 m) in the middle of a corridor was tested in 40 healthy dextral men. One group received 200 mg levodopa, while the other group received placebo. We found that (1). subjects veered less after levodopa than after placebo, and (2). improved straight-walking tendency was most prominent for the levodopa group which veered less often to the right side than the placebo group. These findings imply that spatial orientation skills improved under levodopa. We conjecture that a task-dependent dopamine demand during our task was satisfied by levodopa supplementation, and over-proportionately so by the right hemisphere.

Adult↗

PubMed2003

Magical ideation modulates spatial behavior.

Previous research has found that animals as well as persons with psychotic disorders preferentially orient away from the cerebral hemisphere with the more active dopamine system. This study investigated the modulation of spatial behavior by a mode of thinking reminiscent of the positive symptoms of psychosis. In a non-treatment-seeking sample of healthy volunteers (20 women and 16 men), the authors assessed the lateral biases in turning and veering behavior and in line bisection as a function of their magical ideation, that is, a mild form of schizotypy. Across tasks, pronounced magical ideation was associated with reduced right-sided orientation preferences. This finding suggests a relative hyperdopaminergia of the right hemisphere as the biological basis of magical ideation.

Adult↗

PubMed2002

Do sperm cells remember?

Spontaneous alternation behavior (SAB) is the universal tendency of animals, including unicellular organisms, to alternate directional choices at consecutive left/right branchings while traversing a maze. Occurrence of SAB implies short-term memory, as a current decision is statistically dependent on previous ones. We developed a procedure to assess SAB in human spermatozoa. A total of 1302 progressively motile spermatozoa from healthy donors were observed as they entered one of two mazes, both fabricated by eximer laser ablation. The control maze was a simple T-maze (width=depth=20 microm, distance between entrance and free choice T-intersection=600 microm). The experimental maze was identical to the control maze except for a forced right-turn 600 microm before the T-intersection. We recorded individual sperm cells' left/right decisions at the T-intersections in both mazes. Of the 714 spermatozoa entering the control maze, 49.1% turned to the left (not significantly different from the chance expectation of 50.0%). Of the 588 spermatozoa entering the experimental maze, 58.6% turned left after the initial forced right turn (significant SAB; P=0.041, Wilcoxon). The statistical dependency of a directional decision on a previous one suggests a physiological 'memory' in human spermatozoa. Among the possible underlying mechanisms are refractory processes in structures responsible for flagellar beating, a postulation which deserves further scrutiny with video-monitored single-cell testing.

Humans↗

PubMed2002

Why is magical ideation related to leftward deviation on an implicit line bisection task?

Right hemispatial inattention is a neurocognitive deficit observed in thought-disordered schizophrenia patients, persons with schizotypal personality disorder and healthy participants with high scores on schizotypy scales. We administered a schizotypy inventory, the Magical Ideation (MI) scale, to forty healthy, right-handed men who had copied and later recalled the Rey-Osterrieth complex figure. Implicit line bisection performances were defined as the bisecting lines of the complex figure's large rectangle and were recorded for the copy and delay conditions. MI scores were significantly correlated with a leftward shift in bisections in the delay but not copy condition, indicating a significant relationship between the degree of right hemispatial inattention and number of magical beliefs in healthy participants. We describe a model in which these beliefs are conceptualized as a consequence of a hemispheric imbalance, specifically, of a "right hemisphere processing bias". This model accounts for (1) the leftward shifts in spatial attention and (2) the language deficits associated with psychosis and related symptom clusters which have hitherto been addressed in separate literatures. Clinically, the Rey-Osterrieth test may provide a means to assess implicit hemispatial inattention in psychotic patients.

Adult↗