Functional subdivisions of the temporal lobe neocortex

In order to gather evidence on functional subdivisions of the temporal lobe neocortex of the primate, the activity of more than 2600 single neurons was recorded in 10 myelo- and cytoarchitecturally defined subdivisions of the cortex in the superior temporal sulcus (STS) and inferior temporal gyrus of the anterior part of the temporal lobe of 5 hemispheres of 3 macaque monkeys. First, convergence of different modalities into each area was investigated. Areas TS and TAa, in the upper part of this region, were found to receive visual as well as auditory inputs. Areas TPO, PGa, and IPa, in the depths of the STS, received visual, auditory, and somatosensory inputs. Areas TEa, TEm, TE3, TE2, and TE1, which extend from the ventral bank of the STS through the inferior temporal gyrus, were primarily unimodal visual areas. Second, of the cells with visual responses, it was found that some neurons in areas TS-IPa could be activated only by moving visual stimuli, whereas the great majority of neurons in areas TEa-TE1 could be activated by stationary visual stimuli. Third, it was found that there were few sharply discriminating visual neurons in areas TS and TAa; of the sharply discriminating visual neurons in other areas, however, neurons that responded primarily to faces were found predominantly in areas TPO, TEa, and TEm (in which they represented 20% of the neurons with visual responses); neurons that were tuned to relatively simple visual stimuli such as sine-wave gratings, color, or simple shapes were relatively common in areas TEa, TEm, and TE3; and neurons that responded only to complex visual stimuli were common in areas IPa, TEa, TEm, and TE3. These findings show inter alia that areas TPO, PGa, and IPa are multimodal, that the inferior temporal gyrus areas are primarily unimodal, that there are areas in the cortex in the anterior and dorsal part of the STS that are specialized for the analysis of moving visual stimuli, that neurons responsive primarily to faces are found predominantly in areas TPO, TEa, and TEm, and that architectural subdivisions of the temporal lobe cortex are related to neuronal response properties.     

Suction–curettage with combination of two different cannulae in the treatment of axillary osmidrosis and hyperhidrosis

Objective  To investigate the efficacy and safety of suction–curettage with a combination of two different cannulae for treatment of axillary osmidrosis and hyperhidrosis.
Design  Retrospective analysis of patients who underwent surgery from September 2004 to September 2006.
Setting  Outpatient clinic for hyperhidrosis at a university-affiliated hospital.
Subjects  Sixty-five patients who were treated for axillary malodor and hyperhidrosis.
Interventions  Patients were sequentially treated with Fatemi and Cassio cannulae.
Main outcome measures  Demographic data, severity data (assessment of malodor), degree of satisfaction, sweating, hair growth, scarring, recurrence and complications.
Results  Sixty of the 65 patients (96.9%) had excellent to fair results, and only 2 patients (3.1%) had poor results. Complications occurred in 4 patients (6.2%). Recurrence occurred in 3 patients (4.6%).
Conclusions  This simplified and inexpensive method resulted in a high success rate with low complications and high satisfaction with minimal scarring and rapid recovery.     

Sensory-specific satiety: Food-specific reduction in responsiveness of ventral forebrain neurons after feeding in the monkey

It has been shown previously that some neurons in the lateral hypothalamus and substantia innominata respond to the sight of food, others to the taste of food, and others to the sight or taste of food, in the hungry monkey. It is shown here that feeding to satiety decreases the responses of hypothalamic neurons to the sight and/or taste of a food on which the monkey has been satiated, but leaves the responses of the same neurons to other foods on which the monkey has not been satiated relatively unchanged. This suggests that the responses of these neurons in the ventral forebrain are related to sensory-specific satiety, an important phenomenon which regulates food intake. In sensory-specific satiety, the pleasantness of the sight or taste of a food becomes less after it is eaten to satiety, whereas the pleasantness of the sight or taste of other foods which have not been eaten is much less changed; correspondingly, food intake is greater if foods which have not already been eaten to satiety are offered.     

The neurophysiology of backward visual masking: information analysis.

Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in firing rate because it is the selective part of the firing that is especially attenuated by the mask, not the spontaneous firing, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500-msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates.     

Failure of naltrexone to affect the pleasantness or intake of food.

Two separate studies were conducted to investigate the effects of oral naltrexone on the pleasantness ratings of foods and food intake. In both studies, normal-weight, nondieting males rated hunger, fullness, mood and the pleasantness of the taste of a variety of foods before and after double-blind administration of 50 mg of naltrexone or placebo. All subjects received a test meal, in a counterbalanced, repeated measures design. In the first study, 12 subjects were given a self-selection test meal after overnight deprivation. In the second study 14 subjects were given an ice cream test meal with no deprivation. In both experiments the pleasantness of the taste of the foods, sensory-specific satiety, hunger ratings and overall energy intake were not differentially influenced by naltrexone administration. In Experiment 2, intake of the ice cream was greater after active drug administration because subjects who received active drug on the first session ate less ice cream in the placebo session. In conclusion, in the short term, naltrexone had no impact on hunger, sensory-specific satiety or food intake.     

Angiotensin II-induced thirst and vasopressin release in man

1. The thirst and plasma vasopressin responses to single-blind controlled intravenous angiotensin II infusions (2-16 ng min-1 kg-1) were investigated in ten healthy young men. 2. Thirst and vasopressin secretion were stimulated in four out of ten subjects. These effects occurred at plasma angiotensin concentrations well above those measured under physiological conditions associated with thirst and vasopressin secretion such as water deprivation. 3. Further studies are needed to define why only certain individuals respond to intravenous angiotensin II infusions and to determine whether potentiation of angiotensin-induced thirst and vasopressin secretion by other stimuli (e.g. hypovolaemia and hypertonicity) might occur in man, in particular under pathological conditions when plasma angiotensin levels are above the physiological range.     

Improving serious mental illness through interprofessional education

Current health policies emphasize partnership between professional groups, between agencies and with users, to ensure more integrated health and social care services. However, a number of reasons have been consistently identified as inhibiting interprofessional working. Among the many factors identified are poor communication, conflicting power relations and role confusion, and these present immense challenges to those who wish to offer interprofessional education and training opportunities. East Gloucestershire NHS Trust worked in partnership with the University of Gloucestershire (formerly the Cheltenham and Gloucester College of Higher Education) to overcome these problems and deliver an important postqualifying interprofessional training for those working with people with serious mental illness - the Thorn-based 'Diploma in Integrated Approaches to Serious Mental Illness'. This collaborative initiative represents a good model by which practitioners of all disciplines can be trained to a high standard and meet the requirements of the National Service Framework for Mental Health. This paper describes the initiative and identifies the extent to which the course has, by mirroring the practice it is seeking to generate, 'pulled together' to ensure interprofessional, intersectoral and professional/user collaboration. The key challenges associated with interprofessional working (with people with serious mental illness and with others) and with course implementation and how these were met are discussed and further opportunities are identified.     

Umami: a delicious flavor formed by convergence of taste and olfactory pathways in the human brain

Umami taste is produced by glutamate acting on a fifth taste system. However, glutamate presented alone as a taste stimulus is not highly pleasant, and does not act synergistically with other tastes (sweet, salt, bitter and sour). We show here that when glutamate is given in combination with a consonant, savory, odour (vegetable), the resulting flavor can be much more pleasant. Moreover, we showed using functional brain imaging with fMRI that the glutamate taste and savory odour combination produced much greater activation of the medial orbitofrontal cortex and pregenual cingulate cortex than the sum of the activations by the taste and olfactory components presented separately. Supralinear effects were much less (and significantly less) evident for sodium chloride and vegetable odour. Further, activations in these brain regions were correlated with the pleasantness and fullness of the flavor, and with the consonance of the taste and olfactory components. Supralinear effects of glutamate taste and savory odour were not found in the insular primary taste cortex. We thus propose that glutamate acts by the nonlinear effects it can produce when combined with a consonant odour in multimodal cortical taste-olfactory convergence regions. We propose the concept that umami can be thought of as a rich and delicious flavor that is produced by a combination of glutamate taste and a consonant savory odour. Glutamate is thus a flavor enhancer because of the way that it can combine supralinearly with consonant odours in cortical areas where the taste and olfactory pathways converge far beyond the receptors.     

Warm pleasant feelings in the brain

Warm and cold stimuli have affective components such as feeling pleasant or unpleasant, and these components may have survival value, for approach to warmth and avoidance of cold may be reinforcers or goals for action built into us during evolution to direct our behaviour to stimuli that are appropriate for survival. Understanding the brain processing that underlies these prototypical reinforcers provides a direct approach to understanding the brain mechanisms of emotion. In an fMRI investigation in humans, we showed that the mid-orbitofrontal and pregenual cingulate cortex and the ventral striatum have activations that are correlated with the subjective pleasantness ratings made to warm (41 degrees C) and cold (12 degrees C) stimuli, and combinations of warm and cold stimuli, applied to the hand. Activations in the lateral and some more anterior parts of the orbitofrontal cortex were correlated with the unpleasantness of the stimuli. In contrast, activations in the somatosensory cortex and ventral posterior insula were correlated with the intensity but not the pleasantness of the thermal stimuli. A principle thus appears to be that processing related to the affective value and associated subjective emotional experience of thermal stimuli that are important for survival is performed in different brain areas to those where activations are related to sensory properties of the stimuli such as their intensity. This conclusion appears to be the case for processing in a number of sensory modalities, and the finding with such prototypical stimuli as warm and cold provides strong support for this principle.