Neurochemical manipulation of procedural memory: sequential stimuli learning under influence of phentermine and pentobarbital
✍ Scribed by E. R. Volkerts; M. W. Van Laar; M. N. Verbaten; G. Mulder; R. A. A. Maes
- Book ID
- 101281363
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 186 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0885-6222
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✦ Synopsis
Within the scope of implicit, procedural memory research a large number of empirical studies have been conducted to explore the conditions under which structured sequence learning will emerge in healthy volunteers. Up to now, a few studies have been carried out to determine the eects of scopolamine (an anticholinergic drug) and lorazepam on procedural memory functions. The present study is concerned with the question whether procedural memory functions will also be aected by centrally acting drugs that exert their eects on mechanisms involved in a general state of alertness or attention. For this purpose 24 subjects were treated, double-blind, with phentermine 20 mg (a derivative of amphetamine, known to increase the concentrations of dopamine and noradrenaline), pentobarbital 100 mg (a GABA agonist), or a placebo. Each subject performed a task wherein a structured sequence of items was presented during 24 repetitions. The task consisted of two levels of sequence complexity (easy' and hard') and two levels of pacing (2 and 4 s). MANOVA revealed interaction eects between the drugs and the repetitions of the sequences, indicating that learning of the sequences as a function of the repetitions was improved by phentermine and impaired by pentobarbital. This eect was marginally signi®cant for phentermine in comparison to both pentobarbital and placebo. Further, as a function of the repetitions, a signi®cant decrement in sequence learning was found for pentobarbital only under slow pacing (4 s), in interaction with both levels of sequence complexity, indicating that the learning and retention of procedural knowledge was more retarded in the hard' than in the easy' task condition. Moreover, the results also provide a contribution to experimental procedures that appear to in¯uence procedural memory functioning. It was found that additional eort caused by fast (2 s) pacing, hampers sequence learning in the `hard' condition, highlighting that external pacing, sequence length and pattern complexity caused dierential eects on procedural memory functioning.