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PubMed1984

Trigeminal sensorimotor mechanisms and ingestive behavior.

Selective section of trigeminal orosensory nerves was carried out to assess the contributions of trigeminal orosensation to the control of food and water intake in the rat. Trigeminal orosensory deafferentation reduces a responsiveness to food and water, disrupts jaw-opening and tongue protrusion reflexes mediating eating and drinking, impairs dietary self-selection and reduces the level of long-term body weight regulation. The magnitude of the feeding behavior deficits is a joint function of the extent of the denervation and the sensory properties of the diet, and recovery takes place along a palatability gradient. Analysis of feeding and drinking patterns and of learned instrumental behaviors indicates that deafferentation reduces the probability of initiating a feeding or drinking bout and profoundly disrupts performance of operant responses reinforced with food or water. We conclude that the trigeminal system contributes to both the sensorimotor and motivational control of ingestive behavior. Its motivational contributions differ in both kind and magnitude from those of the gustatory system.

Afferent Pathways↗

PubMed1992

Neural modeling with dynamically adjustable threshold and refractory period.

A variant of the FitzHugh-Nagumo model is proposed in order to fully make use of the computational properties of intraneuronal dynamics. The mechanisms of threshold and refractory periods resulting from the double dynamical processes are qualitatively studied through computer simulation. The results show that the variant neuron model has the property that its threshold, refractory period and response amplitude are dynamically adjustable. This paper has also discussed some problems relating to collective property, learning and implementation of the neural network based on the neuron model proposed. It is noted that the implicit way to describe threshold and refractory period is advantageous to adaptive learning in neural networks and that molecular electronics probably provides an effective approach to implementing the above neuron model.

Animals↗

PubMed2005

Visual cortex activation in late-onset, Braille naive blind individuals: an fMRI study during semantic and phonological tasks with heard words.

Visual cortex activity in the blind has been shown in Braille literate people, which raise the question of whether Braille literacy influences cross-modal reorganization. We used fMRI to examine visual cortex activation during semantic and phonological tasks with auditory presentation of words in two late-onset blind individuals who lacked Braille literacy. Multiple visual cortical regions were activated in the Braille naive individuals. Positive BOLD responses were noted in lower tier visuotopic (e.g., V1, V2, VP, and V3) and several higher tier visual areas (e.g., V4v, V8, and BA 37). Activity was more extensive and cross-correlation magnitudes were greater during the semantic compared to the phonological task. These results with Braille naive individuals plausibly suggest that visual deprivation alone induces visual cortex reorganization. Cross-modal reorganization of lower tier visual areas may be recruited by developing skills in attending to selected non-visual inputs (e.g., Braille literacy, enhanced auditory skills). Such learning might strengthen remote connections with multisensory cortical areas. Of necessity, the Braille naive participants must attend to auditory stimulation for language. We hypothesize that learning to attend to non-visual inputs probably strengthens the remaining active synapses following visual deprivation, and thereby, increases cross-modal activation of lower tier visual areas when performing highly demanding non-visual tasks of which reading Braille is just one example.

Adult↗

PubMed1981

Recent advances in the pathogenesis, diagnosis, and management of otitis media.

1. Otitis media is one of the most common diseases of childhood. 2. Pathogenesis is related to eustachian tube dysfunction. 3. Etiology is primarily bacterial (S. pneumoniae, 40 per cent; H. influenzae, 20 per cent). Bacteria are also present in chronic otitis media with effusion ("secretory otitis"). 4. H. Influenzae is present in all age groups, and 15 to 30 per cent are ampicillin-resistant. 5. Diagnosis is by pneumatic otoscopy, or tympanometry, or both. 6. Tympanocentesis and/or myringotomy is important diagnostic-therapeutic procedure in selected patients. 7. Ampicillin (or amoxicillin) is initial therapy of choice. 8. Erythromycin and sulfonamide, trimethoprim-sulfamethoxazole, or cefaclor is recommended for those who have poor clinical response to initial antimicrobial therapy. 9. Efficacy is yet to be shown for antimicrobial prophylaxis, decongestants, antihistamines, myringotomy and tympanostomy tubes, and adenoidectomy with or without tonsillectomy. 10. Attendant conductive hearing loss is probably related to abnormalities in cognition, language, and learning.

Acoustic Impedance Tests↗

PubMed1997

The communication atmosphere between physician colleagues: competitive perfectionism or supportive dialogue? A Norwegian study.

Open and supportive communication is probably one of the most important promotors of learning, coping and satisfaction at the workplace. The aim of this paper is to describe and predict the communication atmosphere between Norwegian physicians. Twenty statements describing communication, as perceived by the physicians themselves, were presented to a random sample of the members of the Norwegian Medical Association of which more than 90% of the physicians in the country are members (N = 2628). In general, this investigation indicates that the communication atmosphere among Norwegian physicians is characterised by support and mutual respect. More than half of the respondents fully agreed that communication between colleagues in the workplace is marked by solidarity, and that experienced colleagues show respect for the less experienced in both personal and professional matters. Physicians working in hospitals described the communication atmosphere as substantially more selfish and competitive than non-hospital physicians, whilst general practitioners considered the atmosphere between colleagues to be more supportive than non-specialists. In addition, high perceived stress was associated with the perception of a less supportive atmosphere. However, the strongest predictor of the communication atmosphere was clearly the physician's perceived autonomy. The comprehensive retrenchment programmes implemented in Norwegian hospitals during recent years have increased stress and restricted professional autonomy among both physicians and other occupational groups. Our findings indicate that the communication atmosphere necessary to secure continuity of knowledge within the medical profession may have been jeopardised by this process. In the long term, this may prove hazardous to the quality of medical care.

Adult↗

PubMed1998

Memory impairment on a delayed non-matching-to-position task after lesions of the perirhinal cortex in the rat.

Previous research conducted in monkeys and rats has established that the perirhinal cortex is critically involved in object- or stimulus-recognition memory, whereas other research suggests this region may contribute to memory for object discriminations. These findings do not rule out the possibility that the perirhinal cortex plays a more general role in memory. The present experiment addressed whether selective lesions of the perirhinal cortex would result in a delay-dependent deficit on a test of memory that did not involve stimulus recognition or object memory. Rats with bilateral perirhinal lesions were tested on a delayed non-matching-to-position task. Lesions of the perirhinal cortex did not interfere with acquisition or performance at short (0-4 s)-delay intervals, but lesions did impair performance at longer delays. It is suggested that the perirhinal cortex is involved in maintaining representations of trial-specific information over time.

Analysis of Variance↗

PubMed2006

Insight and strategy in multiple-cue learning.

In multiple-cue learning (also known as probabilistic category learning) people acquire information about cue-outcome relations and combine these into predictions or judgments. Previous researchers claimed that people can achieve high levels of performance without explicit knowledge of the task structure or insight into their own judgment policies. It has also been argued that people use a variety of suboptimal strategies to solve such tasks. In three experiments the authors reexamined these conclusions by introducing novel measures of task knowledge and self-insight and using "rolling regression" methods to analyze individual learning. Participants successfully learned a four-cue probabilistic environment and showed accurate knowledge of both the task structure and their own judgment processes. Learning analyses suggested that the apparent use of suboptimal strategies emerges from the incremental tracking of statistical contingencies in the environment.

Analysis of Variance↗

PubMed2006

Retrieval-induced facilitation: initially nontested material can benefit from prior testing of related material.

Classroom exams can assess students' knowledge of only a subset of the material taught in a course. What are the implications of this approach for long-term retention? Three experiments (N = 210) examined how taking an initial test affects later memory for prose materials not initially tested. Experiment 1 shows that testing enhanced recall 24 hr later for the initially nontested material. This facilitation was not seen for participants given additional study opportunities without initial testing. Experiment 2 extends this facilitative effect to a within-subjects design. Experiment 3 demonstrates that this facilitation can be modulated by conscious strategies. These results have implications for educational practice and the theoretical developments of the testing effect, associative memory, and retrieval inhibition.

Adult↗

PubMed1968