Is two times a half more than one? :Is two times a half more than one? Testing the function and evolution of brain lateralization in animals and man Ton Groothuis, Anke Bouma, Bernd Riedstra


Brain lateralization :Brain lateralization Two hemispheres Differ in structure Differ in functional output (perception, cognition, emotion, motor control) Handedness, language in our species


Slide 3:Until recently brain lateralization domain of social sciences (neuro-psychology) Language lateralized function Only humans have language: Only humans lateralized brain for language


Function? :Function? Parallel processing Avoiding inter-hemispheric interference (slow, competition) Avoiding redundant neural operations Hardly any test in humans Evolution totally unclear Descriptive work, ingenious tests, pathology


BUT :BUT Recently biologists discovered lateralization in brain and behaviour in many taxa, including octopus, fish, toads, snakes and lizards, birds, rodents, monkeys and primates. Both in motor output (paw preference), vocal control, perception, emotion Question about evolution now relevant


AND 2 :AND 2 Ontogenetic manipulation of lateralization possible Handling rodents (Denenburg) Early exposure to androgens (rodents, Clark; birds, Rogers) Light exposure (birds, Rogers)


Slide 7:Induction of brain lateralization Riedstra and Groothuis 2003 Effect of maternal Cradling in humans?? (Konishi, Vauchlair)


THUS :THUS Experimental testing of functional hypotheses now possible! Animal models experimental manipulation fMRI At the level of the individual Efficient processing Fitness consequences At the level of the population bias


Slide 9:Organization of workshop Aim: Bringing together a mixture of psychologists and biologists working on lateralization and interested in the topic To discuss the function and evolution of brain lateralization Inventory of hypotheses, possibilities, controversies Preparation of grant proposal


Slide 10:6 keynote speakers, internationally well-known psychologists and biologists Informal, open exchange of idea’s guide lines for speakers Ample time, thorough overview (60 min) Focus on certain topics Provocative statements Ample time for discussion (30 min and 2 hr general discussion) Participation on invitation only, limited to 25 people (50% biologists, 50% psychologists, seniors and PhD students from both the Netherlands and abroad) Distribution of key-papers of speakers


speakers :speakers Dr. J. van Strien (Psychologist, Rotterdam, NL): Introduction and Overview of the “human” field Prof. Dr. G. Vallortigara (Biologist, Trieste, It): Lateralization in the animal kingdom: Function of population bias Dr. D. Zaidel (Psychologist, UCLA, USA) Lateralization of facial expressions and sexual selection


Speakers :Speakers Prof. Dr. O. Güntürkün (bio-psychologist Bochum, D) Ontogenetic plasticity and neurobiology of lateralization in birds Prof. Dr. P. MacNeilage (Psychologist, Texas, USA) Evolution and ontogeny of lateralization and language, in relation to development of fine and complex motor skills Prof. Dr. L. Rogers (Biologist, Armidale, Au) Examples of lateralization in animals; how to test function Power-point presentation with voice


Slide 13:Which “functions” are lateralized? Similar in different species? Common principles? Meaningful comparisons between men and other animals? Function (adaptation) and evolution of lateralization? Which hypotheses? What sort of evidence? Gaps in our knowledge? Testing hypotheses: Which species good models? How to manipulate lateralization (ontogeny) Topics general discussion


Last phase :Last phase Preparation grant application: Organizers and key-note speakers What and how to study lateralization in two complementary projects, one on humans and one on animals. Scope for collaboration


Results and conclusions :Results and conclusions Design highly successful Lots of open discussion, long time slots often still too short Intensive discussions much more valuable than listening to many shorter talks Lots of myths about facts and function Psychology: many valuable techniques and insights Psychology: deviation = pathology; Biology: other adaptive strategy Some confusion about function and evolutionary principles, but all agreed on its relevance Lateralization evolutionary old;fundamental principle Testable hypotheses Time is ripe for interdisciplinary approach Strong willingness to collaborate


The proposal :The proposal Double project Humans and birds complementary work on same questions Ontogenetic plasticity Test of functional hypotheses Fitness consequences Frequency dependent selection


Two different simultaneous tasks :Two different simultaneous tasks


Population bias :Population bias Integrity of shoaling fish in escape response (Bisazza et al) Why small proportion with bias in other direction? 10 % left handedness as pathology? ESS approach: frequency dependent selection Fighting, sports


The proposal :The proposal Special program NWO: Evolution and Behaviour aim: bridging gap psychology and biology Understanding function and evolution of human behaviour Workshop Double project: on humans (PhD student, Anke Bouma) on animals (Postdoc=Bernd Riedstra) pigeon and chicken


Pigeon and chicken :Pigeon and chicken Birds: separate visual fields No corpus collosum Embryo develops outside mothers body Pigeon: Connection ongoing work Fitness measurements Coorporation Prof. Gunturkun Chicken Coorporation Prof. Rogers Aggression


4 topics :4 topics Ontogenetic plasticity of lateralization Prerequisite for rest of the studies Fitness consequences of differences in degree and direction of lateralization Processing capacity How do fitness effects come about? Function of population bias Frequency dependent selection


1. Ontogenetic plasticity :1. Ontogenetic plasticity Pigeon: (year 1) prenatal exposure to light and to androgens (maternal effects?). Visual perception tasks, fMRI? Humans: (year 1 and 2) Early postnatal head position (maternal cradling) and handedness and visual perception (plus fMRI) at 1.5 years Activational effects of androgens on spatial orientation (and fMRI)


2. Fitness consequences :2. Fitness consequences Pigeon (year 2 and 3) Free living colony, composed of birds with experimentally manipulated lateralization and controls: Mortality, reproduction Humans (year 2) Degree and direction of lateralization (handedness and footness) and socio-economic status, health, reproduction


3. Processing capacity :3. Processing capacity Pigeon (year 2) Effect of lateralization manipulation on performance in simultaneous tasks (with Gunturgun, Bochum): food discrimination and predator, sex and individual recognition (global vs local cues) Humans (year 3) Similar tests (visual half-field tests, dichotic listening, discrimination and threatening stimulus) (with van Strien, Rotterdam)


4. Population bias :4. Population bias Pigeon and chicken (year 3) Proportion winning fights depending on degree and direction of lateralization (with Vallortigara, Trieste, It). Humans (year 4) Idem in combatant sports


Slide 27:Visual half field tasks


Slide 28:Motor preferences (hand, foot, whole body) Dichotic listening tasks Neuro-imaging techniques (PET, fMRI)