Biomedical subjects

Martin Eimer

Publications and source records attributed to Martin Eimer.

39 records · Page 3Linked to original sources

PubMed2002

Temporal dynamics of lateralized ERP components elicited during endogenous attentional shifts to relevant tactile events.

To investigate the temporal dynamics of lateralized event-related brain potential (ERP) components elicited during covert shifts of spatial attention, ERPs were recorded in a task where central visual symbolic cues instructed participants to direct attention to their left or right hand in order to detect infrequent tactile targets presented to that hand, and to ignore tactile stimuli presented to the other hand, as well as all randomly intermingled peripheral visual stimuli. In different blocks, the stimulus onset asynchrony (SOA) between cue and target was 300 ms, 700 ms, or 1,100 ms. Anterior and posterior ERP modulations sensitive to the direction of an attentional shift were time-locked to the attentional cue, rather than to the anticipated arrival of a task-relevant stimulus. These components thus appear to reflect central attentional control rather than the anticipatory preparation of sensory areas. In addition, attentional modulations of ERPs to task-irrelevant visual stimuli were found, providing further evidence for crossmodal links in spatial attention between touch and vision.

Adult↗

PubMed2002

Motor activation with and without inhibition: evidence for a threshold mechanism in motor control.

Masked primes presented prior to a target can trigger response activation processes that may later be subject to inhibition. Evidence for response inhibition has previously been obtained with primes presented at fixation, but not with primes presented in the periphery of the visual field. It is argued that this central-peripheral asymmetry reflects a threshold mechanism in motor control. Foveal masked primes give rise to stronger perceptual representations than do peripheral primes, resulting in stronger response activations. Strong response activations are actively inhibited, whereas weaker activations remain below a hypothetical inhibition threshold. Evidence in favor of this hypothesis is obtained in four experiments that manipulated the perceptual strength of foveal and peripheral primes. Experiments 1 and 2 demonstrate that when the perceptual strength of peripheral primes is gradually increased by delaying mask onset, positive prime-target compatibility effects (reflecting the absence of response inhibition) turn into negative effects (indicating the presence of response inhibition). Experiments 3 and 4 demonstrate that when the perceptual strength of foveal primes is gradually decreased by degradation, negative compatibility effects turn into positive effects. The results are discussed in terms of a simple functional model of early motor control.

Adult↗

PubMed2002

Links between conscious awareness and response inhibition: evidence from masked priming.

Recent results from "subliminal priming" experiments have shown that masked prime stimuli which can not be consciously perceived can trigger response activation processes, but that these response activations can later be subject to inhibition. Links between conscious awareness and response inhibition were investigated by manipulating the visibility of masked prime stimuli, from clearly visible primes to prime stimuli that were inaccessible to conscious perception. Response inhibition was observed with unperceived prime stimuli, but not for suprathreshold primes. Correlations between individual prime identification thresholds and the onset of response inhibition indicate that the absence or presence of conscious awareness can predict whether or not response inhibition is elicited. These results demonstrate qualitative differences in the effects of conscious and unconscious information. It is argued that response facilitation produced by consciously available perceptual information can counteract automatic effects of self-inhibitory motor control circuits.

Adult↗