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At least 991 records · Page 55Linked to original sources
PubMed1998

Processing of twitter-call fundamental frequencies in insula and auditory cortex of squirrel monkeys.

Amplitude-modulated (AM) and frequency-modulated (FM) elements are prominent periodic sound features of squirrel monkeys' twitter calls. To investigate how the periodic FM elements are represented in the spike activity of cortical neurons, single units in the insula, primary auditory field (AI) and rostral auditory field (R) were recorded. In five monkeys, 566 units (insula, n = 181; AI, n = 221; R, n = 164) were exposed to synthesized fundamental frequencies and one natural twitter call. Neuronal encoding of periodic FM elements takes place by phase-locking to either the up- or the down-directed FM sweeps. The phase-locking was strongly influenced by the FM-period repetition rate. The ability of neurons in both auditory fields and the insula to encode all periodic FM elements showed a marked reduction at 16 Hz FM-period repetition rate. The neurons' best frequency (BF) influenced the quality of periodicity encoding, but neurons with BFs outside the frequency range of the fundamentals also responded with periodic discharge rates. Even neurons in AI (6.8%) and the insula (22.6%) that did not respond to pure tones showed clear periodic FM encoding. The percentage of neurons able to encode all periodic FM elements within the twitter fundamental was significantly higher in field R than in AI and the insula. From 58 simultaneously recorded pairs of units in AI and the insula that had positive cross-correlation coefficients of spontaneous activity, the influence of the FM-period repetition rate on neuronal correlation was investigated. Correlated firing of AI and insula neurons seems limited to low-period repetition rates. The cross-correlation coefficients obtained for spontaneous activity and six different periodic FM sounds showed a band-pass characteristic. The natural twitter call evoked stronger neuronal responses in all fields than the synthesized fundamental frequencies with corresponding bi-directional FM sweeps. The better encoding of the transient features in the natural call can be attributed to the amplitude modulation added to the FM elements in the natural call. These amplitude modulations divide the FM elements of twitter calls into syllable-like sound elements. It is probable that encoding the complex pattern in the time and frequency domains of a call must undergo some integration at a cortical level. Additionally, these data provide the first evidence that insula neurons contribute to the encoding of complex FM signals.

Acoustic Stimulation↗
PubMed2003

Do infant Japanese macaques ( Macaca fuscata) categorize objects without specific training?

In the present study, we examined whether infant Japanese macaques categorize objects without any training, using a similar technique also used with human infants (the paired-preference method). During the familiarization phase, subjects were presented twice with two pairs of different objects from one global-level category. During the test phase, they were presented twice with a pair consisting of a novel familiar-category object and a novel global-level category object. The subjects were tested with three global-level categories (animal, furniture, and vehicle). It was found that they showed significant novelty preferences as a whole, indicating that they processed similarities between familiarization objects and novel familiar-category objects. These results suggest that subjects responded distinctively to objects without training, indicating the possibility that infant macaques possess the capacity for categorization.

Analysis of Variance↗
PubMed1981

Calcitropic hormone responsiveness during pregnancy.

Release of the calcitropic hormones parathyroid hormone (PTH) and calcitonin (CT) in-response to provocative stimuli was assessed in pregnant rhesus monkeys tested three times during gestation (corresponding to the end of each trimester) and again 6 weeks post partum. In the case of PTH, although basal levels were higher during pregnancy than post partum and tended to increase with advancing gestation, similar to observations in human subjects, the incremental response of the hormone to a hypocalcemic stimulus was diminished in pregnant animals and tended to lessen with advancing gestation. Basal CT levels were also increased during pregnancy but, in contrast to PTH, the incremental CT response to a provocative stimulus was generally greater during pregnancy than post partum and tended to increase with advancing gestation. The explanation of these findings may lie in differing degrees of hormone storage. These adjustments in maternal endocrine physiology regulating calcium metabolism would have the net effect of tending to preserve the maternal skeleton by protecting it from excessive resorption at times of hypocalcemia and promoting increased calcium storage during episodes of hypercalcemia.

Animals↗
PubMed1982

Reduction of generalized aversive responding in a post-treatment cancer patient: relaxation as an active coping skill.

A male ostomy patient was successfully taught relaxation as an active coping skill to control generalized aversive gastric upset responses which had originally developed in the context of radiation therapy. Because the patient had completed his medical regimen, intervention focused on applied relaxation outside the medical center setting. Treatment involved minimal therapist contact. The results are discussed in terms of assessing aversive side effects which generalize beyond the course of medical treatment, and the contingent aspects of such treatments. The efficiency of relaxation programs, as well as the importance of active patient involvement, are also discussed.

Adaptation, Psychological↗
PubMed1983

Cross-correlation analysis of the response of units in the dorsal spinocerebellar tract (DSCT) to muscle stretch and contraction.

Activity of DSCT units was cross-correlated with stimuli evoking gastrocnemius-soleus muscle stretch or contraction in order to investigate the muscle receptor input to DSCT. The most potent stimulus was generally muscle contraction, and the most common response one of inhibition. The similarity in response of many units to stretch, contraction and nerve simulation suggests that Golgi tendon organs are prominent source of input to DSCT, and that much of this input is inhibitory.

Action Potentials↗