The 2nd-4th digit ratio (2D:4D) and neck circumference: implications for risk factors in coronary heart disease.

BACKGROUND: The ratio of the lengths of the 2nd and 4th digit (2D:4D) is negatively related to prenatal and adult concentrations of testosterone (T). Testosterone appears to be a protective against myocardial infarction (MI) in men as men with low 2D:4D are older at first MI than men with high 2D:4D, and men with coronary artery disease have lower T levels than men with normal angiograms. Neck circumference (NC), a simple and time-saving screening measure to identify obesity is reported to be positively correlated with the factors of the metabolic syndrome, a complex breakdown of normal physiology characterized by obesity, insulin resistance, hyperlipidemia, and hypertension, and is therefore likely to increase the risk of coronary heart disease (CHD). OBJECTIVE: To investigate possible associations between 2D:4D ratios and NC in men and women. RESEARCH METHODS AND PROCEDURES: 2D:4D ratios, NC, along with measures of waist and hip circumferences, body mass index (BMI), and waist-to-hip ratio was recorded from 127 men and 117 women. RESULTS: A significant positive correlation between 2D:4D and NC and was found for men but not for women after controlling for body mass index (BMI); the higher the ratio the higher the NC. DISCUSSION: This finding supports the suggestion of NC to serve as a predictor for increased risk for CHD as previously suggested. In addition, the present association suggests a predisposition for men towards CHD via 2D:4D as proxy to early sex-steroid exposure.

The biology of facial beauty.

It was once widely believed that standards of beauty were arbitrarily variable. Recent research suggests, however, that people's views of facial attractiveness are remarkably consistent, regardless of race, nationality or age. Facial characteristics are known to influence human attractiveness judgements and evolutionary psychologists suggest that these characteristics all pertain to health, leading to the conclusion that humans have evolved to view certain bodily features as attractive because the features were displayed by healthy others. Here we review some of the fundamental principles of sexual selection theory that apply to human beauty and summarize the major findings of human beauty perception.

Second to fourth digit ratio, body mass index, waist-to-hip ratio, and waist-to-chest ratio: their relationships in heterosexual men and women.

BACKGROUND: Prenatal sex steroids have been broadly discussed in terms of their possible effect on brain differentiation, whereas pubertal/adult sex hormones are thought to be the main regulators of sexually dimorphic physical features in males and females. Assessing prenatal steroid exposure has previously been difficult but evidence now suggests that finger length ratio may provide a 'window' into prenatal hormone exposure. The length of the second digit (the index finger) relative to the length of the fourth digit (the ring finger) is sexually dimorphic as males have a lower second to fourth digit ratio (2D:4D). The sexual dimorphism is determined as early as the 14th week of fetal life, and remains unchanged at puberty. There is evidence that sex differences in 2D:4D arise from in utero concentrations of sex steroids, with a low 2D:4D (male typical ratio) being positively related to prenatal testosterone, while a high 2D:4D (female typical ratio) is positively associated with prenatal oestrogen. AIM: The studied aimed to determine whether, and to what extent, adult sexually dimorphic physical traits, which are largely determined at puberty, relate to traits that are largely determined in utero. This work examined the relationship between three sexually dimorphic traits--body mass index (BMI), waist-to-hip ratio (WHR) and waist-to-chest ratio (WCR)--and digit ratio. PARTICIPANTS AND METHODS: BMI, WHR and WCR were assessed in 30 heterosexual male and 50 heterosexual female participants by recording their body height, weight, and measuring their waist, hip and chest circumference. Digit lengths of the second and fourth fingers were measured from photocopies of the ventral surface of the hand and by actual finger measurements. RESULTS: Digit ratio was found to be significantly lower in men than in women. Significant negative correlations were found between female's left and right hand 2D:4D, waist and hip circumference, and WCR. In males, BMI was found to be positively related to digit ratio but remained significant only for left hand 2D:4D. Generally, the relationships were stronger for females than for males. Although not all relationships were found to be significant, they were in accord with our predictions. CONCLUSION: In addition to an activational effect of sex hormones at puberty, the present data suggest an early organizational effect of sex hormones through the association between indices of female body shape, male BMI, and human finger length patterns.

A randomised, controlled trial of cognitive and psychomotor recovery from midazolam sedation following reversal with oral flumazenil.

Flumazenil is traditionally administered intravenously to reverse the adverse effects of over sedation with benzodiazepines. The aim of this study was to test postoperative cognitive and psychomotor recovery from midazolam conscious sedation, following reversal with orally administered flumazenil. It was hypothesised that when administered by the oral route, flumazenil may enhance recovery over a prolonged period, thus increasing safety. Eighteen patients requiring intravenous midazolam sedation for dental treatment completed a randomised, double-blind, crossover trial. Following treatment the patients' sedation was reversed using either flumazenil or saline (as placebo), administered orally, on alternate appointments. Assessment of mood and cognitive function were undertaken using ClinPhone.cdr(R), a highly sensitive and specific computerised battery of cognitive tests administered by telephone prior to sedation and every hour for seven hours post reversal. Results indicate that within 20 min of administration, oral flumazenil is capable of partially reversing some cognitive and psychomotor impairments but the attentional and stimulus discrimination effects of midazolam sedation still remain.

A randomised crossover trial of post-operative cognitive and psychomotor recovery from benzodiazepine sedation: effects of reversal with flumazenil over a prolonged recovery period.

OBJECTIVE: To study the post-operative cognitive and psychomotor recovery from midazolam conscious sedation, after reversal with the benzodiazepine antagonist flumazenil over a prolonged recovery period. DESIGN: A prospective, double-blind, randomised, crossover trial. SETTING: Out-patient Sedation Department, Newcastle Dental Hospital and School METHOD: Eighteen patients, ASA I or II, received midazolam on two separate occasions to undergo equivalent dental treatment. Following treatment patients were reversed with intravenous flumazenil or saline (placebo) at alternate appointments. Assessment of mood and cognitive function was undertaken using a highly sensitive and specific computerised battery of cognitive tests administered by telephone. Cognitive and psychomotor tests were administered prior to sedation and every hour for 6 hours post reversal. RESULTS: Results indicated no significant effect of flumazenil on simple reaction time and choice reaction time but did show a trend of reversing the effects of midazolam on numeric working memory and word recognition. CONCLUSION: The cognitive and psychomotor effects of the sedation were not fully reversed by flumazenil. Cognitive impairments were still present up to 6 hours post-reversal, despite patients appearing clinically more alert. This has important implications for treatment protocols and discharge instructions.

Dose-dependent effects of flumazenil on cognition, mood, and cardio-respiratory physiology in healthy volunteers.

OBJECTIVES: To assess the possible effects of flumazenil on cognitive processing, physiology, and mood. Design A double-blind, placebo controlled, four-way cross-over study, using healthy volunteers. METHODS: On each of 4 separate visits, 16 participants received 0.5 mg, 2.5 mg, 5.0 mg of flumazenil, or normal saline. They then performed a computerised test battery assessing cognitive function. Measures of pulse rate, arterial oxygen saturation and mean arterial pressure were also taken. Finally, participants completed visual analogue scales assessing their subjective mood state. RESULTS: The majority of cognitive tasks showed dose-dependent declines in performance. Mean arterial pressure was significantly reduced, as was pulse rate. Subjective alertness showed a similar decline. CONCLUSIONS: Flumazenil has been clinically described as an agent with few intrinsic properties, whose primary effect lies in its ability to reverse benzodiazepine-induced states. This study has shown that flumazenil does possess intrinsic activity which have a significant effect on cognition, cardiovascular physiology and mood. Clinicians need to be aware of these effects.

Cognitive performance, hyperoxia, and heart rate following oxygen administration in healthy young adults.

It was recently established that supplemental oxygen administration significantly enhances memory formation in healthy young adults. In the present study, a double-blind, placebo-controled design was employed to assess the cognitive and physiological effects of subjects' inspiration of oxygen or air (control) prior to undergoing simple memory and reaction-time tasks. Arterial blood oxygen saturation and heart rate were monitored during each of six phases of the experiment, corresponding to baseline, gas inhalation, word presentation, reaction time, distractor and word recall, respectively. The results confirm that oxygen administration significantly enhances cognitive performance above that seen in the air inhalation condition. Subjects who received oxygen recalled more words and had faster reaction times. Moreover, compared to participants who inhaled air, they exhibited significant hyperoxia during gas administration, word presentation, and the reaction-time task, but not at other phases of the experiment. Compared to baseline, heart rate was significantly elevated during the word presentation, reaction-time, and distractor tasks in both the air and oxygen groups. In the oxygen group, significant correlations were found between changes in oxygen saturation and cognitive performance. In the air group, greater changes in heart rate were associated with more improved cognitive performance. These results are discussed in the context of cognitive demand and metabolic supply. It is suggested that under periods of cognitive demand a number of physiological responses are brought into play that serve to increase the delivery of metabolic substrates to active neural tissue. These mechanisms can be supplemented by increased availability of circulating blood oxygen, resulting in an augmentation of cognitive performance. Heart rate reactivity and the capacity for increased blood oxygen appear to be important physiological individual differences mediating these phenomena.

Sex differences in cognition: the role of testosterone and sexual orientation.

The performance of both heterosexual and homosexual males and females was compared on four cognitive tasks which have been shown to reveal evidence of sexual dimorphism. In one spatial and one verbal task, significant sex and orientation effects were found. Significant relationships were also found between salivary free-testosterone levels and performance on both spatial tasks, but no significant associations were found for performance on the two verbal tasks. The present study revealed both within- and between-sex differences in cognition and indicates that these differences may be partly accounted for by the activational effects of free testosterone.

Cognitive properties of sedation agents: comparison of the effects of nitrous oxide and midazolam on memory and mood.

OBJECTIVES: To compare the effects of nitrous oxide and midazolam on cognition and mood. DESIGN: A three-way, counterbalanced, cross-over study, using patients receiving conscious sedation for routine dental treatment. METHODS: On each of three separate visits, patients performed a computerised test battery to determine baseline cognitive performance. Then, following administration of either midazolam, nitrous oxide, or no drug, patients re-performed the test battery. Finally, patients completed visual analogue scales assessing their subjective mood state. RESULTS: Relative to baseline performance, midazolam administration produced significantly slower reaction times compared with nitrous oxide and no-drug conditions. Furthermore, patients receiving midazolam were impaired in accuracy relative to the other conditions on many of the cognitive tasks, particularly those assessing the recall of information. Patient performance in nitrous oxide and control conditions did not significantly differ. These results could not be explained by differences in mood between the conditions, as subjective mood ratings during midazolam or nitrous oxide administration were very similar. CONCLUSIONS: It is important for clinicians to be aware that peri-operative recall of information is reduced in patients who have undergone midazolam sedation. This is an advantage for patients who are anxious, and do not wish to be aware of the operative treatment being performed. However, as the cognitive impairment is enduring, an adult escort and written post-operative instructions should be mandatory for midazolam sedation patients. In contrast, the use of nitrous oxide sedation does not significantly impair higher cognitive tasks and thus patients receiving nitrous oxide sedation can resume normal activities in the post-operative period.

Evidence for the involvement of the mammillary bodies and cingulum bundle in allocentric spatial processing by rats.

Comparisons were made between the behavioural effects of lesions in three inter-related limbic structures: the mammillary bodies, the fornix and the cingulum bundle/cingulate cortex. Cytotoxic lesions of the mammillary nuclei produced a marked deficit on reinforced T-maze alternation, but performance gradually improved with practice. Subsequent tests in a cross-maze and a radial-arm maze showed that the animals with mammillary body lesions failed to use allocentric cues, but were able to perform normally in an egocentric discrimination. Three groups of rats with different patterns of either crossed or unilateral radio frequency lesions of the cingulate region were given the same tasks. The profile of results indicated that disruption of those fibres in the cingulum bundle connecting the anterior thalamic nuclei with the hippocampal/retrohippocampal region was responsible for the observed impairments to T-maze alternation and radial-arm maze performance. There was also evidence that disconnection of frontal connections in the cingulum bundle might affect perseverative behaviour, but not allocentric processing. The results add support to the notion of a functional circuit that involves projections from the hippocampus to the mammillary bodies and anterior thalamic nuclei, and from there back to hippocampal/retrohippocampal regions via the cingulum bundle. This circuit appears to be vital for normal allocentric processing.

Spontaneous object recognition and object location memory in rats: the effects of lesions in the cingulate cortices, the medial prefrontal cortex, the cingulum bundle and the fornix.

The first experiment assessed the effects of neurotoxic lesions in either the anterior cingulate cortex (ACc) or the retrosplenial cortex (RSc) on a test of object recognition. Neither lesion affected performance on this task, which takes advantage of the rat's normal preference to spend more time investigating novel rather than familiar stimuli. In response to this negative result, a second experiment assessed the effects of much more extensive cingulate lesions (Cg) on both object recognition and object location memory. The latter task also used a preference measure, but in this case it concerned preference for a novel location. For comparison purposes this second study included groups of rats with lesions in closely allied regions: the fornix (Fx), the cingulum bundle (CB) and the medial prefrontal cortex (Pfc). Comparisons with sham-operated control rats showed that none of the four groups (Cg, Fx, CB, Pfc) was impaired on the object recognition task, adding further weight to the view that these structures are not necessary for assessing stimulus familiarity. The Fx and Cg groups were, however, impaired on the object location task, suggesting that these regions are necessary for remembering other attributes of a stimulus (spatial location).

The effects of selective lesions within the anterior thalamic nuclei on spatial memory in the rat.

Groups of rats received cytotoxic lesions centred in either the anterior thalamic nucleus (AM), the anterior ventral and anterior dorsal thalamic nuclei (AV/AD), or all three nuclei combined (ANT.T). These lesions were made by injecting N-methyl-D-aspartate acid (NMDA). These rats, and a group of surgical controls (SHAM), were trained on a rewarded forced-alternation task in a T-maze. While the selective AM and AV/AD lesions produced an initial acquisition impairment, only the animals with combined lesions (ANT.T) showed a persistent deficit throughout the 16 acquisition sessions. Subsequent testing with a cross-maze confirmed that the SHAM, AV/AD, and AM groups were able to use allocentric cues, while the ANT.T group were impaired. In contrast none of the three anterior groups were impaired on a subsequent egocentric discrimination and reversal task run in the same apparatus. A final test using the eight arm radial-maze, revealed marked deficits in the ANT.T group as well as milder deficits in the AV/AD group. The results from these experiments help to confirm the importance of the anterior thalamic nuclei for allocentric tasks, but suggest that no region is pre-eminently important. The findings also help to account for other studies which have reported that anterior thalamic lesions have seemingly mild effects on tests of spatial memory.

Neurotoxic lesions of the perirhinal cortex do not mimic the behavioural effects of fornix transection in the rat.

The effects of perirhinal (Prh) and fornix (Fx) lesions were compared on a series of spatial and nonspatial memory tests. These tests included delayed nonmatching-to-position in an operant chamber, a spatial (lever) discrimination and its subsequent reversals, delayed spatial alternation in a T-maze, and an object recognition memory test using both normal objects and "re configured' objects. As expected, the rats with fornix lesions were impaired on all of the spatial tests. Their performance on the recognition test was, however, left intact. The perirhinal lesions produced a quite different pattern of results. Animals with these lesions were unimpaired on all three spatial tasks, but displayed evidence of an impairment on the object recognition test. This impairment was restricted to the longer delay (15 min) and was only found with the normal objects. These findings suggest that the actions of the perirhinal cortex and the hippocampus can be dissociated from one another.

The effects of discrete cingulum bundle lesions in the rat on the acquisition and performance of two tests of spatial working memory.

Rats received one of three different surgeries in which radiofrequency lesions were made in the cingulum bundle. These consisted of either: (i) two pairs of bilateral lesions at the mid and posterior levels of the tract (M + PCB, n = 9); (ii) a single pair of bilateral lesions at the posterior level of the tract (PCB, n = 5); or (iii) a single lesion in each hemisphere, one at a posterior level the other at a mid level (CCB, n = 6). Twelve other animals acted as surgical controls (SHAM). None of the groups of animals with cingulum bundle lesions was impaired on either the acquisition or performance of an automated delayed nonmatching-to-position task in an operant chamber. In fact, following combination of the three cingulum bundle groups it was found that the lesions resulted in a small, but significant improvement in performance of this task when compared with the SHAM animals. All three groups with tract lesions were, however, impaired on an alternation task in a T-maze. This double dissociation between the two tests of spatial working memory, coupled with the comparable scores of the three lesion groups, is seen as showing that the cingulum bundle is part of a neuroanatomical circuit subserving aspects of allocentric spatial memory. The relative mildness of the alternation deficit in the present study also suggests that the bundle must be completely destroyed bilaterally to produce a pronounced deficit.

A comparison of the effects of medial prefrontal, cingulate cortex, and cingulum bundle lesions on tests of spatial memory: evidence of a double dissociation between frontal and cingulum bundle contributions.

Rats were trained on an automated delayed nonmatching-to-position (DNMP) task. They then received cytotoxic lesions in either the medial prefrontal cortex (n = 13) or the cingulate and retrosplenial cortices (n = 8), or radiofrequency lesions in either the fornix (n = 6) or the cingulum bundle (n = 8). Twelve animals served as surgical controls. Only the fornical and medial prefrontal lesions disrupted DNMP performance, both groups showing a loss of accuracy and an increase in bias. The rats were then trained on a lever discrimination and reversal task, the medial prefrontal and fornical groups showing evidence of an increase in bias when compared with the cingulate cortex group. Finally, the rats were trained on a forced alternation task in a T-maze. Marked deficits were observed in the fornix and cingulum bundle groups, but the medial prefrontal and cingulate groups were unimpaired. The double dissociation between the effects of the prefrontal and cingulum bundle lesions highlights the very different nature of the two spatial tasks (DNMP and T-maze alternation), even though both involved a nonmatching rule. These findings may reflect the involvement of divergent outputs from the fornix-anterior thalamic pathway. One possibility is that anterior thalamic projections to the medial prefrontal cortex are concerned with processing egocentric information, while anterior thalamic projections to temporal regions via the cingulum bundle are concerned with allocentric information. The results also indicate that the effects of conventional lesions in the cingulate cortex and medial prefrontal cortex may be compromised by additional damage to the cingulum bundle.

A comparison of the effects of anterior thalamic, mamillary body and fornix lesions on reinforced spatial alternation.

The effects of cytotoxic lesions in either the anterior thalamic nuclei or the mamillary bodies were compared with those of fornix lesions on a test of spatial working memory. All three lesions impaired acquisition of a forced alternation task in a T-maze, but the disruptive effects of the mamillary body lesions were significantly less than those following either fornix or anterior thalamic damage. When the alternation task was changed, so as to increase proactive interference, the impairment associated with mamillary body damage became more evident and was now equal in severity to that in the animals with anterior thalamic lesions. The fornix lesion group were the most impaired. In contrast, all three groups performed normally on a test of object recognition. The results add weight to the view that hippocampal--anterior thalamic connections are critical for normal spatial memory and that the relative contribution of the mamillary bodies is task dependent.

Handedness and longevity: archival study of cricketers.

OBJECTIVE: To test whether handedness is associated with a change in longevity. DESIGN: Archival survey. SETTING: British Isles. SUBJECTS: All first class cricketers born before 1961 whose bowling hand was specified (right, n = 5041; left, n = 1132) in a comprehensive encyclopaedia. MAIN OUTCOME MEASURES: Bowling hand and life span. RESULTS: Regression analysis of the 5960 players born between 1840 and 1960 (3387 dead, 2573 alive) showed no significant relation between mortality and handedness (P = 0.3). Left handedness was, however, associated with an increased likelihood of death from unnatural causes (P = 0.03, log hazard 0.37, 95% confidence interval 0.04 to 0.70). This effect was especially related to deaths during warfare (P = 0.009, log hazard 0.53, 0.13 to 0.92). CONCLUSION: Left handedness is not, in general, associated with an increase in mortality.

Lack of effect of lesions in the anterior cingulate cortex and retrosplenial cortex on certain tests of spatial memory in the rat.

The effects of cytotoxic lesions in either the anterior cingulate cortex or the retrosplenial cortex were compared with those of fornix lesions on three tests of spatial memory. Two of the tasks, delayed nonmatching-to-position and spatial reversal learning, were tested in an automated apparatus. The third task, forced alternation, was tested in a T-maze. Neither anterior cingulate nor retrosplenial cortex damage produced any significant impairment on the three tasks. In contrast, rats with fornix lesions (hippocampal system damage) were markedly impaired on all three tasks. The results, which were considered in the light of proposals for a hippocampal--anterior thalamic--cingulate system that is important for spatial memory, suggest that neither of the cingulate regions involved in this study form a critical subcomponent of this proposed system. It is therefore assumed that the cingulate cortices are only critical for certain classes of spatial problem. It is also suggested that in some previous studies the effects of inadvertent damage to the cingulum bundle may have contributed to the apparent effects of cingulate lesions.