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Chapter 3. The Biological basis of Behavior. Communication in the Nervous System. Hardware: Glia – structural support and insulation Neurons – communication Soma – cell body Dendrites – receive Axon – transmit away. Myelin sheath – speeds up transmission

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chapter 3

Chapter 3

The Biological basis of Behavior

communication in the nervous system
Communication in the Nervous System
  • Hardware:
    • Glia – structural support and insulation
    • Neurons – communication
    • Soma – cell body
    • Dendrites – receive
    • Axon – transmit away
slide3

Myelin sheath – speeds up transmission

  • Terminal Button – end of axon; secretes neurotransmitters
  • Neurotransmitters – chemical messengers
  • Synapse – point at which neurons interconnect
the neural impulse electrochemical beginnings
The Neural Impulse: Electrochemical Beginnings
  • Hodgkin & Huxley (1952) - giant squid
    • Fluids inside and outside neuron
    • Electrically charged particles (ions)
    • Neuron at rest – negative charge on inside compared to outside
    • -70 millivolts – resting potential
the neural impulse the action potential
The Neural Impulse: The Action Potential
  • Stimulation causes cell membrane to open briefly
  • Positively charged sodium ions flow in
  • Shift in electrical charge travels along neuron
  • The Action Potential
  • All – or – none law
slide7

Synaptic cleft

  • Presynaptic neuron
    • Synaptic vesicles
    • Neurotransmitters
  • Postsynaptic neuron
    • Receptor sites
when a neurotransmitter binds the postsynaptic potential
When a Neurotransmitter Binds: The Postsynaptic Potential
  • Voltage change at receptor site – postsynaptic potential (PSP)
    • Not all-or-none
    • Changes the probability of the postsynaptic neuron firing
  • Positive voltage shift – excitatory PSP
  • Negative voltage shift – inhibitory PSP
signals from postsynaptic potentials to neural networks
Signals: From Postsynaptic Potentials to Neural Networks
  • One neuron, signals from thousands of other neurons
  • Requires integration of signals
    • PSPs add up, balance out
    • Balance between IPSPs and EPSPs
  • Neural networks
    • Patterns of neural activity
    • Interconnected neurons that fire together or sequentially
  • Synaptic connections
    • Elimination and creation
    • Synaptic pruning – Figure 3.5
neurotransmitters
Neurotransmitters
  • Specific neurotransmitters work at specific synapses
    • Lock and key mechanism
  • Agonist – mimics neurotransmitter action
  • Antagonist – opposes action of a neurotransmitter
  • 15 – 20 neurotransmitters known at present
  • Interactions between neurotransmitter circuits
  • Botox – Ach blocker
  • Dopamine – substantia nigra – Parkinson disease
organization of the nervous system
Organization of the Nervous System
  • Central nervous system (CNS) – brain and spinal cord
    • Afferent = toward the CNS/ Efferent = away from the CNS
  • Peripheral nervous system – nerves that lie outside the central nervous system
    • Somatic nervous system– voluntary muscles and sensory receptors
    • Autonomic nervous system (ANS) – controls automatic, involuntary functions
      • Sympathetic – Go (fight-or-flight)
      • Parasympathetic – Stop
the cranial nerves and their function
The Cranial Nerves and Their Function
  • 1 – Olfactory - smell S
  • 2 – Optic – vision S
  • 3 – Occulomotor – eye movements, control of pupil and lens, tears MP
  • 4 – Trochlear - eye movements M
  • 5 – Trigeminal – facial sensations, chewing SM
  • 6 – Abducens - eye movements M
  • 7 – Facial – facial muscles, salivary glands, taste SMP
  • 8 – Auditory – acoustic branch: audition S verstibular branch: balance S
  • 9 – Glossopharynegeal – throat muscles, salivary glands, taste SMP
  • 10 – Vagus – parasympathetic control of internal organs, sensation from internal organs, taste SMP
  • 11 – Spinal accessory – head and neck muscles M
  • 12 – Hypoglossal – tongue and neck muscles M

S, sensory; M, motor; P, parasympatheic function

studying the brain research methods
Studying the Brain: Research Methods
  • Electroencephalography (EEG) – F 3.10
  • Damage studies/lesioning
  • Electrical stimulation (ESB) – F 3.11
  • Transcortical Magnetic Stimulation (TMS) – F 3.12
  • Brain imaging –
    • computerized tomography – CT – F 3.13
    • positron emission tomography - PET – F 3.14
    • magnetic resonance imaging – MRI – F 3.15
    • functional magnetic resonance imaging – fMRI – F 3.15
slide23

PET scan

MRI and fMRI scans

slide26
Functional MRI images showing reduced activation of language areas during a linguistic task in patients with schizophrenia
brain regions and functions
Brain Regions and Functions
  • Hindbrain – vital functions – medulla, pons, and cerebellum
  • Midbrain – sensory functions – dopaminergic projections, reticular activating system
  • Forebrain – emotion, complex thought – thalamus, hypothalamus, limbic system, cerebrum, cerebral cortex
the cerebrum two hemispheres four lobes
The Cerebrum: Two Hemispheres, Four Lobes
  • Cerebral Hemispheres – two specialized halves connected by the corpus collosum –
    • Left hemisphere – verbal processing: language, speech, reading, writing, sequential
    • Right hemisphere – nonverbal processing: spatial, musical, visual recognition, parallel
  • Four Lobes: -
    • Occipital – vision
    • Parietal – somatosensory – phantom limb –
    • Temporal - auditory
    • Frontal – movement, executive control systems –
  • Primary functions and associated functions
    • Language – Broca’s and Wernicke’s areas – loss of language – aphasia –
mirror neurons
Mirror Neurons
  • An area just forward of the primary motor cortex is where “mirror neurons” were first discovered accidentally in the mid-1990s.
    • May play a role in the acquisition of new motor skills,
      • the imitation of others,
      • the ability to feel empathy for others,
      • and dysfunctions in mirror neuron circuits may underlie the social deficits seen in autistic disorders.
the plasticity of the brain
The Plasticity of the Brain
  • The brain is more “plastic” or malleable than widely assumed
    • Aspects of experience can sculpt features of brain structure
    • Damage to incoming sensory pathways or tissue can lead to neural reorganization
  • Adult brain can generate new neurons – neurogenesis
the endocrine system glands and hormones
The Endocrine System: Glands and Hormones
  • Hormones – chemical messengers in the bloodstream
    • Pulsatile release by endocrine glands
    • Negative feedback system
  • Endocrine glands
    • Pituitary – “master gland,” growth hormone
    • Thyroid - metabolic rate
    • Adrenal - salt and carbohydrate metabolism
    • Pancreas - sugar metabolism
    • Gonads - sex hormones
  • Use of steroids
genes and behavior the interdisciplinary field of behavioral genetics
Genes and Behavior: The Interdisciplinary Field of Behavioral Genetics
  • Behavioral genetics = the study of the influence of genetic factors on behavioral traits
  • Basic terminology:
  • Chromosomes – strands of DNA carrying genetic information
    • Human cells contain 46 chromosomes in pairs (sex-cells – 23 single)
    • Each chromosome – thousands of genes, also in pairs
  • Dominant, recessive
  • Homozygous, heterozygous
  • Genotype/Phenotype and PolygenicInheritance
research methods in behavioral genetics
Research Methods in Behavioral Genetics
  • Family studies – does it run in the family?
  • Twin studies – compare resemblance of identical (monozygotic) and fraternal (dizygotic) twins on a trait
  • Adoption studies – examine resemblance between adopted children and their biological and adoptive parents
modern approaches to the nature vs nurture debate
Modern Approaches to the Nature vs. Nurture Debate
  • Molecular Genetics = the study of the biochemical bases of genetic inheritance
    • Genetic mapping – locating specific genes - The Human Genome Project
  • Behavioral Genetics
    • The interactionist model
    • Richard Rose (1995) – “We inherit dispositions, not destinies.”
evolutionary psychology behavior in terms of adaptive significance
Evolutionary Psychology: Behavior in Terms of Adaptive Significance
  • Based on Darwin’s ideas of natural selection
    • Reproductive success key
  • Adaptations – behavioral as well as physical
    • Fight-or-flight response
    • Taste preferences
    • Parental investment and mating
parental investment and mating systems sociobiology
Parental Investment and Mating Systems - sociobiology
  • Polygyny – high female, low male – based on a study by Buss (1994) found in 84 % of human cultures
  • Polyandry – high male, low female – rare but examples have been found for example in the Pahari of Nepal and India, and Tibet and other limited places in the world. The system in Tibet was based on class and land considerations.

http://www.case.edu/affil/tibet/booksAndPapers/pahari.html

  • Monogamy – shared parental investment but not always equal. There are few exclusively monogamous species – 15 % of human cultures (Buss, 1994)
  • Polygynadry – group parental investment and very rare – in chimpanzees mating is promiscuous for males and females
  • Incest – universal taboo – increased genetic diversity