Matz Larsson

Passive smoking and respiratory symptoms in the FinEsS Study

The aim of the present study was to examine the relationship between reported environmental tobacco smoke (ETS) exposure and respiratory symptoms. In 1996, a postal questionnaire was randomly distributed in three areas of Estonia to a population-based sample, of which 4,995 females and 1,822 males had never smoked. The main outcome measures were current respiratory symptoms and the amount of reported ETS exposure outside the home. ETS exposure at home was more common in females (31% versus 19%), while exposure outside of the home was more common in males (53% versus 7%). Females reported more symptoms from tobacco smoke than males (37.7% versus 21.6%). If ETS exposure outside of the home exceeded 5 h daily, the risk for wheeze (odds ratio (OR) 2.67, 95% confidence interval (CI) 1.98–3.61) and physician-diagnosed asthma (OR 1.79, 1.02–3.16) were increased. ETS exposure outside of the home was shown to be strongly related to almost all respiratory symptoms in a dose/response manner. ETS exposure at home did not show significantly elevated ORs for any respiratory symptoms. This study shows that females seem to be more troubled by environmental smoke exposure than males and provides further evidence of the serious health hazards associated with environmental smoke exposure. Indeed, the findings of this study support a ban on smoking in the workplace and public areas.

Self-generated sounds of locomotion and ventilation and the evolution of human rhythmic abilities.

AbstractIt has been suggested that the basic building blocks of music mimic sounds of moving humans, and because the brain was primed to exploit such sounds, they eventually became incorporated in human culture. However, that raises further questions. Why do genetically close, culturally well-developed apes lack musical abilities? Did our switch to bipedalism influence the origins of music? Four hypotheses are raised: (1) Human locomotion and ventilation can mask critical sounds in the environment. (2) Synchronization of locomotion reduces that problem. (3) Predictable sounds of locomotion may stimulate the evolution of synchronized behavior. (4) Bipedal gait and the associated sounds of locomotion influenced the evolution of human rhythmic abilities. Theoretical models and research data suggest that noise of locomotion and ventilation may mask critical auditory information. People often synchronize steps subconsciously. Human locomotion is likely to produce more predictable sounds than those of non-human primates. Predictable locomotion sounds may have improved our capacity of entrainment to external rhythms and to feel the beat in music. A sense of rhythm could aid the brain in distinguishing among sounds arising from discrete sources and also help individuals to synchronize their movements with one another. Synchronization of group movement may improve perception by providing periods of relative silence and by facilitating auditory processing. The adaptive value of such skills to early ancestors may have been keener detection of prey or stalkers and enhanced communication. Bipedal walking may have influenced the development of entrainment in humans and thereby the evolution of rhythmic abilities.

Maternal smoking during pregnancy and physical control and coordination among offspring

Background To examine if smoking during pregnancy is associated with poorer motor competence among offspring, indicating impaired neurological function. The measures may be less susceptible to socioeconomic confounding than cognition tests. Methods Data were from 13 207 members of the National Child Development Study, born in Great Britain in 1958. Maternal smoking during pregnancy was recorded prospectively. Tests of physical control and coordination administered by a school doctor at age 11 years were: time to pick up 20 matches (PUM), number of squares marked (NSM) and copying designs (CD). PUM and NSM were tested for left and right hand. Test scores were dependent variables in linear regression analysis, with adjustment for maternal smoking during pregnancy, sex, birth weight standardised for gestational age, breast-feeding, social class, parental education, mothers age, laterality and pubertal development. Results After adjustment, heavy smoking during pregnancy was statistically significantly associated with PUM (non-dominant hand) and CD, but not NSM; particularly among boys. The regression coefficients (and 95% CI) for PUM (non-dominant hand) are 1.474 (0.47 to 2.48, p=0.004) and 1.203 (0.15 to 2.26, p=0.026) for boys and girls, respectively: higher scores indicate poorer performance. The coefficients for CD are −0.185 (−0.32 to −0.05, p=0.006) for boys and 0.020 (−0.11 to 0.15, p=0.753) for girls: lower scores indicate poorer performance. Conclusions Smoking during pregnancy is associated with subtly reduced motor competence, particularly on the non-dominant side. Statistically significant effect modification by sex was observed for only one test, providing equivocal evidence of a sex difference.

Incidental sounds of locomotion in animal cognition

The highly synchronized formations that characterize schooling in fish and the flight of certain bird groups have frequently been explained as reducing energy expenditure. I present an alternative, or complimentary, hypothesis that synchronization of group movements may improve hearing perception. Although incidental sounds produced as a by-product of locomotion (ISOL) will be an almost constant presence to most animals, the impact on perception and cognition has been little discussed. A consequence of ISOL may be masking of critical sound signals in the surroundings. Birds in flight may generate significant noise; some produce wing beats that are readily heard on the ground at some distance from the source. Synchronization of group movements might reduce auditory masking through periods of relative silence and facilitate auditory grouping processes. Respiratory locomotor coupling and intermittent flight may be other means of reducing masking and improving hearing perception. A distinct border between ISOL and communicative signals is difficult to delineate. ISOL seems to be used by schooling fish as an aid to staying in formation and avoiding collisions. Bird and bat flocks may use ISOL in an analogous way. ISOL and interaction with animal perception, cognition, and synchronized behavior provide an interesting area for future study.

Tool-use-associated sound in the evolution of language

Abstract Proponents of the motor theory of language evolution have primarily focused on the visual domain and communication through observation of movements. In the present paper, it is hypothesized that the production and perception of sound, particularly of incidental sound of locomotion (ISOL) and tool-use sound (TUS), also contributed. Human bipedalism resulted in rhythmic and more predictable ISOL. It has been proposed that this stimulated the evolution of musical abilities, auditory working memory, and abilities to produce complex vocalizations and to mimic natural sounds. Since the human brain proficiently extracts information about objects and events from the sounds they produce, TUS, and mimicry of TUS, might have achieved an iconic function. The prevalence of sound symbolism in many extant languages supports this idea. Self-produced TUS activates multimodal brain processing (motor neurons, hearing, proprioception, touch, vision), and TUS stimulates primate audiovisual mirror neurons, which is likely to stimulate the development of association chains. Tool use and auditory gestures involve motor processing of the forelimbs, which is associated with the evolution of vertebrate vocal communication. The production, perception, and mimicry of TUS may have resulted in a limited number of vocalizations or protowords that were associated with tool use. A new way to communicate about tools, especially when out of sight, would have had selective advantage. A gradual change in acoustic properties and/or meaning could have resulted in arbitrariness and an expanded repertoire of words. Humans have been increasingly exposed to TUS over millions of years, coinciding with the period during which spoken language evolved. ISOL and tool-use-related sound are worth further exploration.

Parental smoking and allergic sensitization in offspring defined by skin prick testing

Investigations of parental smoking during childhood and allergic sensitization have produced contradictory results, but this may be because of variations in the definition of allergy and other influences. We investigated associations of parental smoking with an objective measure of allergy, skin prick testing (SPT), and considered associations with maternal and paternal smoking, independently of each other. A stratified random sample, aged 22–74 yr, of 720 Swedish FinEsS‐study members were skin prick tested for 15 allergens. Subjects with at least one positive SPT were defined as atopic. Data on childhood exposures, including parental smoking, were collected by structured interview. Logistic regression used atopy as the dependent variable. After adjustment, paternal smoking was statistically significantly associated with an increased risk and maternal smoking a non‐statistically significant decreased risk in offspring, with odds ratios (and 95% confidence intervals) of 1.48 (1.04–2.10) and 0.73 (0.48–1.12), respectively. Analysis of families with a non‐smoking mother produced an odds ratio for paternal smoking of 1.61 (1.09–2.37). The negative association between maternal smoking and atopy may not operate through passive smoke exposure and could conceal a significant increased risk associated with passive exposure to tobacco smoke in childhood.

The optic chiasm: a turning point in the evolution of eye/hand coordination

The primate visual system has a uniquely high proportion of ipsilateral retinal projections, retinal ganglial cells that do not cross the midline in the optic chiasm. The general assumption is that this developed due to the selective advantage of accurate depth perception through stereopsis. Here, the hypothesis that the need for accurate eye-forelimb coordination substantially influenced the evolution of the primate visual system is presented. Evolutionary processes may change the direction of retinal ganglial cells. Crossing, or non-crossing, in the optic chiasm determines which hemisphere receives visual feedback in reaching tasks. Each hemisphere receives little tactile and proprioceptive information about the ipsilateral hand. The eye-forelimb hypothesis proposes that abundant ipsilateral retinal projections developed in the primate brain to synthesize, in a single hemisphere, visual, tactile, proprioceptive, and motor information about a given hand, and that this improved eye-hand coordination and optimized the size of the brain. If accurate eye-hand coordination was a major factor in the evolution of stereopsis, stereopsis is likely to be highly developed for activity in the area where the hands most often operate.The primate visual system is ideally suited for tasks within arm’s length and in the inferior visual field, where most manual activity takes place. Altering of ocular dominance in reaching tasks, reduced cross-modal cuing effects when arms are crossed, response of neurons in the primary motor cortex to viewed actions of a hand, multimodal neuron response to tactile as well as visual events, and extensive use of multimodal sensory information in reaching maneuvers support the premise that benefits of accurate limb control influenced the evolution of the primate visual system. The eye-forelimb hypothesis implies that evolutionary change toward hemidecussation in the optic chiasm provided parsimonious neural pathways in animals developing frontal vision and visually guided forelimbs, and also suggests a new perspective on vision convergence in prey and predatory animals.

Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination

It is commonly proposed that the number of fibers that do not cross in the optic chiasm (OC) is proportional to the size of the binocular visual field, and that the major advantage of binocular vision is acute depth perception. I present an alternative, an ‘eye-forelimb’ (EF) hypothesis, suggesting that alterations in the OC influence the length of neural pathways that transmit visual information to motor nuclei and somatosensory areas involved in forelimb coordination. Evolutionary processes resulting in increased ipsilateral retinal projections (IRP) are of adaptive value in animals that regularly use the forelimbs in a frontal position, while evolutionary change towards reduced IRP is of value for animals that mainly use the forelimbs in lateral positions. Primates and cats, to a large extent, use visually guided forelimb maneuvers, and both groups have high proportions of IRP. The fact that vertebrates’ IRP arise exclusively from the temporal retina supports the hypothesis, since IRP from the nasal retina would increase the length of neural pathways involved in forelimb coordination. The EF hypothesis offers new perspectives on why a high proportion of IRP among early limbless vertebrates became reduced during the evolution of laterally situated limbs, and why reptiles that lost their limbs (snakes) evolved more IRP. Anatomical, neurophysiological, phylogenetic, ontogenetic and ecological data suggest that mutations changing the proportions of ipsilateral visual connections in the OC may have selective value for EF coordination.

Binocular vision, the optic chiasm, and their associations with vertebrate motor behavior

Ipsilateral retinal projections (IRP) in the optic chiasm (OC) vary considerably. Most animal groups possess laterally situated eyes and no or few IRP, but, e.g. cats and primates have frontal eyes and high proportions of IRP. The traditional hypothesis that bifocal vision developed to enable predation or to increase perception in restricted light conditions applies mainly to mammals. The eye-forelimb (EF) hypothesis presented here suggests that the reception of visual feedback of limb movements in the limb steering cerebral hemisphere was the fundamental mechanism behind the OC evolution. In other words, that evolutionary change in the OC was necessary to preserve hemispheric autonomy. In the majority of vertebrates, motor processing, tactile, proprioceptive, and visual information involved in steering the hand (limb, paw, fin) is primarily received only in the contralateral hemisphere, while multisensory information from the ipsilateral limb is minimal. Since the involved motor nuclei, somatosensory areas, and vision neurons are situated in same hemisphere, the neuronal pathways involved will be relatively short, optimizing the size of the brain. That would not have been possible without, evolutionary modifications of IRP. Multiple axon-guidance genes, which determine whether axons will cross the midline or not, have shaped the OC anatomy. Evolutionary change in the OC seems to be key to preserving hemispheric autonomy when the body and eye evolve to fit new ecological niches. The EF hypothesis may explain the low proportion of IRP in birds, reptiles, and most fishes; the relatively high proportions of IRP in limbless vertebrates; high proportions of IRP in arboreal, in contrast to ground-dwelling, marsupials; the lack of IRP in dolphins; abundant IRP in primates and most predatory mammals, and why IRP emanate exclusively from the temporal retina. The EF hypothesis seams applicable to vertebrates in general and hence more parsimonious than traditional hypotheses.

Is the Capacity for Vocal Learning in Vertebrates Rooted in Fish Schooling Behavior

The capacity to learn and reproduce vocal sounds has evolved in phylogenetically distant tetrapod lineages. Vocal learners in all these lineages express similar neural circuitry and genetic factors when perceiving, processing, and reproducing vocalization, suggesting that brain pathways for vocal learning evolved within strong constraints from a common ancestor, potentially fish. We hypothesize that the auditory-motor circuits and genes involved in entrainment have their origins in fish schooling behavior and respiratory-motor coupling. In this acoustic advantages hypothesis, aural costs and benefits played a key role in shaping a wide variety of traits, which could readily be exapted for entrainment and vocal learning, including social grouping, group movement, and respiratory-motor coupling. Specifically, incidental sounds of locomotion and respiration (ISLR) may have reinforced synchronization by communicating important spatial and temporal information between school-members and extending windows of silence to improve situational awareness. This process would be mutually reinforcing. Neurons in the telencephalon, which were initially involved in linking ISLR with forelimbs, could have switched functions to serve vocal machinery (e.g. mouth, beak, tongue, larynx, syrinx). While previous vocal learning hypotheses invoke transmission of neurons from visual tasks (gestures) to the auditory channel, this hypothesis involves the auditory channel from the onset. Acoustic benefits of locomotor-respiratory coordination in fish may have selected for genetic factors and brain circuitry capable of synchronizing respiratory and limb movements, predisposing tetrapod lines to synchronized movement, vocalization, and vocal learning. We discuss how the capacity to entrain is manifest in fish, amphibians, birds, and mammals, and propose predictions to test our acoustic advantages hypothesis.