stimulusdependent

Stimulusdependent or stimulus-dependent refers to a property, response, or process that manifests only when a specific external stimulus (or set of stimuli) is present. Such dependence means the phenomenon is not expressed in the absence of the cue and may be reversible when the stimulus is removed.

In neuroscience and psychology, many physiological responses are stimulus-dependent: sensory-evoked neural activity, reflexive actions, and memory retrieval that is facilitated by cues. The strength and occurrence of these responses often scale with stimulus intensity or quality, and some responses emerge only when the appropriate sensory input is received.

In pharmacology and cell biology, the term covers situations in which an observed effect requires both a stimulus and a trigger such as receptor occupancy, second messengers, or an inducer molecule. Inducible gene expression systems rely on a stimulus to turn on transcription; likewise, many ion channels or signaling pathways are gated by ligand binding or other stimuli.

In ecology and behavior, organisms may show stimulus-dependent behaviors such as phototaxis or thermotaxis, and seed germination that requires particular environmental cues like light, temperature, or moisture. The concept helps explain why certain traits or responses appear only under specific environmental conditions and clarifies how organisms adapt to changing environments.