Psychophysiological Construct Models

Sensory Gating. Pre-Pulse inhibition (PPI) is a paradigm in which the construct of gating can be studied in laboratory animals, usually rodents (Light and Braff, 1999; Kilts, 2001). Similar to the human paradigm, PPI measures the response to a loud auditory stimulus (120-dB click) when it is presented alone, as compared to when it is preceded by a soft click (15-dB pre-pulse). Animals will startle less to the loud click when it is preceded (100 m sec) by a soft click than when it is presented alone. This model is very similar to the paradigm used in humans except that in humans, an evoked potential (P50) is measured 50 msec after the presentation of the loud stimulus through electrodes placed on the scalp, whereas in rodents it is measured 40 msec after the presentation of the stimulus (N40) through electrodes placed in the skull, or in the CA3 region of the hippocampus. More commonly in the rodent, sensory gating is measured in the same paradigm as the amplitude of startle (pre-pulse inhibition of startle) as a flinch in the neck musculature, or in the whole body.

Latent Inhibition. The latent inhibition paradigm is used to measure selective attention in animals. Similar to the human paradigm, the noncontingent presentation of a stimulus attenuates its ability to enter into subsequent associations. In the animal paradigm water licks are paired with foot shock, whereas in the human paradigm nonsense syllables are paired with white noise (Gray, 1998; Kilts, 2001). Latent inhibition has face value in that it is facilitated by typical and atypical antipsychotic agents and disrupted by drugs that worsen symptoms of schizophrenia (Moser et al., 2000).

0 0

Post a comment