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Biomedical subjects

N J Cepeda

Publications and source records attributed to N J Cepeda.

3 recordsLinked to original sources

Memory for visual motion.

Observers briefly viewed random dots moving in a given direction and subsequently recalled that direction. When required to remember a single direction, observers performed accurately for memory intervals of up to 8 s; this high-fidelity memory for motion was maintained when observers executed a vigilance task during the memory interval. When observers tried to remember multiple directions of motion, performance deteriorated with increasing number of directions. Still, memory for multiple directions was unchanged over delays of up to 30 s. In a forced-choice experiment, observers viewed 2 successive animation sequences separated by a memory interval; for both sequences, dots moved in any direction within a limited bandwidth. Observers accurately judged which animation sequence was more coherent, even with memory intervals of 30 s. The findings are considered within the context of cognitive bias and memory for other aspects of perception.

Adult

Unitary correlates of linguo-pharyngeal events in a dyskinetic rat model.

1. The hypoglossal nucleus unitary correlates of ketamine- and electrically induced tongue contractions and swallowing events were recorded and compared in stereotaxically mounted rats. 2. Very few of the units recorded could be identified as motoneurons by antidromic invasion through electrical stimulation of the hypoglossal nerve. 3. The sample consists of 109 units, 2/3 of which were located in the retrusor pool and 1/3 in the protrusor region. 4. Linguo-pharyngeal events were considered to be electrically induced if they followed consistently, and with a relatively fixed latency, a single electrical pulse delivered to the superior laryngeal nerve, and ketamine-induced if no such time-locked sequence existed or if they occurred in the absence of electrical stimulation. 5. No differences could be discovered between the two types of linguo-pharyngeal events whether they were compared at the polygraphic or the unitary level. 6. These findings suggest that pharmacologically (ketamine)-induced dyskinetic activity does not differ from comparable motor patterns induced by classical electrophysiological means.

Animals