Representation of Auditory Task Components and of Their Relationships in Primate Auditory Cortex.

The current study aimed to resolve some of the inconsistencies in the literature on which mental processes affect auditory cortical activity. To this end, we studied auditory cortical firing in four monkeys with different experience while they were involved in six conditions with different arrangements of the task components sound, motor action, and water reward. Firing rates changed most strongly when a sound-only condition was compared to a condition in which sound was paired with water.

Neuronal Correlates of Auditory Streaming in Monkey Auditory Cortex for Tone Sequences without Spectral Differences.

This study finds a neuronal correlate of auditory perceptual streaming in the primary auditory cortex for sequences of tone complexes that have the same amplitude spectrum but a different phase spectrum. Our finding is based on microelectrode recordings of multiunit activity from 270 cortical sites in three awake macaque monkeys. The monkeys were presented with repeated sequences of a tone triplet that consisted of an A tone, a B tone, another A tone and then a pause.

Rhythm sensitivity in macaque monkeys.

This study provides evidence that monkeys are rhythm sensitive. We composed isochronous tone sequences consisting of repeating triplets of two short tones and one long tone which humans perceive as repeating triplets of two weak and one strong beat. This regular sequence was compared to an irregular sequence with the same number of randomly arranged short and long tones with no such beat structure.

Anxiety level and body weight changes in rats living in overpopulated cages.

Behavioral indicators of anxiety and body weight dynamics were compared in rats kept under standard conditions (4-5 animals per cage) and in overpopulated cages (17 rats per cage). The behavior of rats exposed to overcrowding for a short and long period was evaluated in the open field, light-darkness, and elevated plus-maze tests. The anxiety parameters of animals increased only in the light-darkness test during the acute period of overcrowding and in all tests during chronic overcrowding.