Andrew Culberson | PubMed Health

PubMed2004

Preparatory activity in visual cortex indexes distractor suppression during covert spatial orienting.

The deployment of spatial attention induces retinotopically specific increases in neural activity that occur even before a target stimulus is presented. Although this preparatory activity is thought to prime the attended regions, thereby improving perception and recognition, it is not yet clear whether this activity is a manifestation of signal enhancement at the attended locations or suppression of interference from distracting stimuli (or both). We investigated the functional role of these preparatory shifts by isolating a distractor suppression component of selection. Behavioral data have shown that manipulating the probability that visual distractors will appear modulates distractor suppression without concurrent changes in signal enhancement. In 2 experiments, functional magnetic resonance imaging revealed increased cue-evoked activity in retinotopically specific regions of visual cortex when increased distractor suppression was elicited by a high probability of distractors. This finding directly links cue-evoked preparatory activity in visual cortex with a distractor suppression component of visual selective attention.

Adult↗

PubMed2003

Lesions of the Basal forebrain cholinergic system impair task acquisition and abolish cortical plasticity associated with motor skill learning.

The contribution of the basal forebrain cholinergic system in mediating plasticity of cortical sensorimotor representations was examined in the context of normal learning. The effects of specific basal forebrain cholinergic lesions upon cortical reorganization associated with learning a skilled motor task were investigated, addressing, for the first time, the functional consequences of blocking cortical map plasticity. Results demonstrate that disrupting basal forebrain cholinergic function disrupts cortical map reorganization and impairs motor learning. Cholinergic lesions do not impair associative fear learning or overall sensorimotor function. These results support the hypothesis that the basal forebrain cholinergic system may be specifically implicated in forms of learning requiring plasticity of cortical representations.

Acetylcholine↗