Constraining Stroke Order During Manual Symbol Learning Hinders Subsequent Recognition in Children Under 4 1/2 Years.

In the age of technology, writing by hand has become less common than texting and keyboarding. Learning letters by hand, however, has been shown to have profound developmental importance. One aspect of writing by hand that has been understudied is the effect of learning symbols stroke-by-stroke, a dynamic action that does not occur with keyboarding. We trained children to draw novel symbols in either an instructed stroke order or in a self-directed stroke order and tested: (1) whether learning novel symbols in a self-directed stroke order benefits subsequent recognition more than learning in a specified stroke order, (2) whether seeing novel symbols unfold in the stroke order that was taught would aid in recognition, and (3) whether any effects are age-dependent. Our results demonstrate that producing a symbol with a self-directed stroke order provides more benefit to symbol recognition than instructed stroke orders in 4.0-4.5-year-old children but not in 4.5-5.0-year-old children. We found, further, that the observed recognition benefits were not affected by seeing the symbol unfold in the same stroke order it was learned during testing, suggesting that the learning was not reliant upon the exact stroke order experienced during learning. These results stress the importance of allowing children to produce symbols in a self-directed manner and, by extension, that constraining how a child learns to write can adversely affect subsequent recognition.

Only self-generated actions create sensori-motor systems in the developing brain.

Previous research shows that sensory and motor systems interact during perception, but how these connections among systems are created during development is unknown. The current work exposes young children to novel 'verbs' and objects through either (a) actively exploring the objects or (b) by seeing an experimenter interact with the objects. Results demonstrate that the motor system is recruited during auditory perception only after learning involved self-generated interactions with objects. Action observation itself led to above-baseline activation in one motor region during visual perception, but was still significantly less active than after self-generated action. Therefore, in the developing brain, associations are built upon real-world interactions of body and environment, leading to sensori-motor representations of both objects and words.

Role of dopamine D3 receptors in the expression of conditioned fear in rats.

There has been considerable interest in the role of dopamine D(3) receptors in appetitive conditioning but few studies have examined their role in aversive conditioning. The present study examined the effect of the dopamine D(3) receptor-preferring partial agonist BP 897 (1-(4-(2-naphthoyl-amino)butyl)-4-(2-methoxyhenyl)-1A-piperazine hydrochloride) and the selective dopamine D(3) receptor antagonist SB-277011A (trans-N-[4-[2-(6-cyano-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl]syclohexyl]4-quinolininecarboxamide]) on the expression and acquisition of fear conditioning. Rats (N=143) received 3 conditioned stimulus-shock pairings and then received 15 conditioned stimulus-alone presentations (3 per day) while lever pressing for food. Response suppression was taken as the behavioral measure of fear. Rats showed strong suppression to the conditioned stimulus after it had been paired with shock and suppression progressively weakened over conditioned stimulus-alone presentations. In experiment 1, rats that received BP 897 (1.0, 2.0 mg/kg i.p.) or SB-277011A (10.0 mg/kg i.p.) prior to conditioned stimulus-alone presentation sessions showed reduced suppression to the conditioned stimulus as compared to rats that received vehicle or lower doses of drug (0, 0.1 mg/kg BP 897; 0, 0.5, 5.0 mg/kg SB-277011A). Injections of BP 897 (1.0, 2.0 mg/kg) or SB-277011A (10.0 mg/kg) prior to conditioned stimulus-shock pairings did not significantly affect subsequent response suppression. Thus, BP 897 and SB-277011A dose-dependently attenuated the expression but not the acquisition of conditioned fear. These findings suggest that BP 897 and SB-277011A reduce the control of responding by aversively conditioned stimuli.

Nucleus accumbens PKA inhibition blocks acquisition but enhances expression of amphetamine-produced conditioned activity in rats.

RATIONALE: The nucleus accumbens (NAc) plays a central role in dopamine-produced reward-related learning. In previous studies, the cyclic adenosine monophosphate-dependent protein kinase (PKA) inhibitor Rp-Cyclic 3',5'-hydrogen phosphorothioate adenosine triethylammonium salt (Rp-cAMPS) blocked the acquisition but not expression of NAc reward-related learning for natural rewards and the acquisition of psychostimulant drug conditioning. OBJECTIVES: The current study assessed the role of PKA in the expression of NAc amphetamine (amph)-produced conditioning using conditioned activity (CA). MATERIALS AND METHODS: After 5 days of habituation, a test environment was paired with bilateral NAc injections of amph (0.0 or 25.0 micro g) and the PKA inhibitor Rp-cAMPS (0.0, 5.0, 10.0, or 20.0 micro g) over three 60-min conditioning sessions separated by 48 h. To test for effects on expression, some groups received vehicle or amph alone before conditioning sessions and were injected with 0.0, 0.25, 5.0, or 20.0 mug of Rp-cAMPS before the single 60-min test session. RESULTS: Amph produced acute increases in locomotion and robust CA. Rp-cAMPS impaired the acquisition of amph-produced CA but not its expression; in fact, it enhanced expression. CONCLUSIONS: Results show that PKA inhibition blocks the acquisition but not the expression of amph-produced conditioning.