Chapter 1 (MT1) Flashcards
Intro to Brain and Behaviour
Reasons for linking the study of the brain and behaviour
How the brain produces behaviour is a major scientific question
Brain is most complex organ, and found in many groups of animals
Growing list of behavioural disorders can be explained/treated as we increase our understanding of the brain
What are the two types of cells in the brain?
Half and half, neurons (87 billion) and glial cells (86 billion)
Where are most of the interconnections between brain and body made?
Spinal cord (tube of nervous tissue encased in our vertebrae)
Spinal cord sends nerve fibers out to our muscles and organs, and received fibers from sensory receptors
Central nervous system
Brain and spinal cord (nervous system encased in bone)
Core structure and core structure mediating behaviour
Peripheral nervous system
All processes that radiate beyond the brain and spinal cord
Divisions of the brain
Cerebrum, or forebrain (two symmetrical hemispheres), responsible for most conscious behaviours
Brainstem, set of structures responsible for most unconscious behaviours. The cerebellum (second major brainstem structure) is specialized for learning and coordinating movements
Embodied behaviour
Proposes that movements we make and perceive in others are central to our behaviour (non verbal communication)
Brain cannot be separated from the bodies activities
Studies relating brain and behaviour
Sensory deprivation (unpleasant, hallucinations to create sensory world)
Locked in syndrome (intact brain but inactive nerve fiber pathways that produce movement, frustrating and helpless)
Minimally conscious state (administering small electrical current to improve patient’s behaviour)
Persistent vegetative state (consciousness present in absence of voluntary movement)
Plasticity
Brain’s ability to change in response to learning experience
Three classic theories of brain/behaviour relationship
Mentalism (Aristotle)
Dualism (Descartes)
Materialism (Darwin)
Mentalism
(Aristotle)
Persons mind (or soul/psyche) is responsible for behaviour
Beginning of modern psychology (prevalent today)
Psyche (mentalism)
Nonmaterial entity, independent of body but responsible for consciousness, perceptions, emotions, and works through the heart
Dualism
(Descartes)
Retained that nonmaterial mind governs rational behaviour
Developed mechanical explanation for how mind interacts with body to produce movement - working through pineal body (pineal gland)
Concluded that mind instructs pineal body, which lies beside fluid filled brain cavities (ventricles), which direct fluid through nerves to fill muscles (produce movement)
Mind and body (two) = dualism
Actual role of pineal body (gland)
Related to biological rhythms
(body functions regulated by biological clock)
Mind-body problem (dualism)
Inability of dualism to explain how nonmaterial mind and physical brain interact
Materialism
(Darwin)
The nervous system can explain rational behaviour
Supported by evolutionary theory
Summary of materialism (relation to evolutionary theory)
Because all animal species are related, their brains must be related
Because all animal species are related, their behaviour must be related
Brains and behaviours in complex animals evolved from simpler animals’ brains/behaviours
Natural selection
Theory explaining how new species evolve and how existing species change over time - desirable/advantageous traits passed down
Phenotype
Set of individual characteristics we can see/measure
What did Mendel discover
That heritable traits (genes) govern physical traits displayed by the species
Genotype
Particular genetic makeup of individual
Members of species (can breed together) with a genotype are likely to express similar phenotypic traits (similar characteristics due to similar genes)
Epigenetics
(beyond genes)
Studies how gene expression is turned on or off at different times - how environment/expression influence our behaviour through their effects on our genes
Evolution of brain/behaviour
animal brain cells (700 million)
first brain (250 million)
humanlike brain (6 million)
modern human brain (200,000)
Evolution of animal nervous system
- Neurons and muscles
- Nerve net (no structure, consists entirely of neurons)
- Bilateral symmetry
- Segmentation (division into similar parts)
- Ganglia (collection of nerve cells that functions like a brain)
- Spinal cord
- Brain
Primate order
(Humans are members of)
Highly developed vision - excellent colour and 3D vision
What is the more complex behaviour in chordates linked to?
Evolution of cerebrum and cerebellum
How do we relate brain size and behaviour?
- Encephalization quotient
- Counting brain cells (amount and packing density of neurons)
- Brain cell connections
Encephalization quotient
Quantitative measure of brain size obtained from ratio of actual to expected brain size (size relative to body weight), among which we deviate the most above the expected line
Brain cell connections
Brains become larger by addition of neurons - and more neurons adds more connections between neurons
Why did the hominid brain enlarge?
- Climate changes (adapt to environment)
- Primate lifestyle (social group size, food selection/forging - better chance of survival)
- Altered maturation (prolonged infancy)
- Changes in physiology (cooking food)
- Human genome
Criticisms of the suggestion that there is a relationship between brain size and behaviour
- How do we measure a brain (difficult)
- Correlating brain size and intelligence (difference in physiology can correspond to difference in brain size)
- Defining intelligence (IQ tests and accurate intelligence testing are a matter of controversy)
Correspondence between brain size and intelligence
Between species (yes)
Within species (no)
Culture
Learned behaviours (passed from generations, enabled by our large brain
