Dissociation of autonomic and behavioral components of conditioned fear during development in the rat.

Abstract

Classical conditioning of heart rate (HR) was examined in unrestrained preweanling and weanling (16-, 19-, 21-, 25-, and 28-day-old) rats, with tone and light as the conditioned stimuli (CS) and electric shock as the unconditioned stimulus. The conditioned cardiac response was a sustained deceleration in HR which did not emerge until Day 21 for the tone CS and until Day 28 for the light CS. In contrast, when suppression of a behavioral response (running in a straight alley for dry suckling as reward) was used as the index of conditioning, the suppressive effects of the CS were evident around Day 16 for the tone and around Day 19 for the light. These findings indicate that during ontogenesis (a) the behavioral and autonomic responses to the same conditioned stimulus do not develop at the same pace, (b) the emergence of conditioned responses to tone and light stimuli parallel the sequential order in which the relevant sensory modalities achieve maturity (first audition, next vision), and (c) there is no clear-cut interdependence between development of the HR orienting response and conditionability of HR because unconditioned cardiac deceleration to both auditory and visual stimuli first appears about Day 16 in the developing rat, well before conditioned HR responses can be established to either stimulus.

Ontogeny of long-term, nonassociative memory in the rat

“…A. Campbell & Ampuero, 1985). Taken together, these results confirm the general principle put forth by many investigators (Harlow, 1959;Piaget & Inhelder, 1969;Rudyet al, 1984) that simple types of leaming emerge earlier in development than do more complex forms.…”

Trace and long-delay fear conditioning in the developing rat

“…Moreover, the animals were able to learn about an auditory cue at a younger age than they were able to learn about a visual cue. This sequential development of learning across different sensory systems is a robust finding in the developmental literature (e.g., Alberts, 1984;Campbell & Ampuero, 1985;Hunt & Campbell, 1997).…”

Ontogeny of classical and operant learning behaviors in zebrafish

“…This window (generally occurring between 2 and 3 wk after birth) is common for many different paradigms such as different forms of Pavlovian fear conditioning and eyeblink conditioning (Campbell and Ampuero 1985;Moye and Rudy 1985;Paczkowski et al 1999;Raineki et al 2009). Moreover, studies of Pavlovian fear conditioning in infant hooded rats have found a dissociation in time between the ability to first detect visual events and to use these for associative learning (Moye and Rudy 1985).…”

“…While there are studies that have followed the ontogeny of learning behaviors in animal model systems of classical conditioning paradigms (Campbell and Ampuero 1985;Moye and Rudy 1985;Paczkowski et al 1999;Raineki et al 2009), the ontogeny of operant learning, in particular, remains much less explored.…”