week 7

• Anatomy of the CNS

  Brain and spinal cord
• Organization of the mammalian nervous systems

  • Main functional regions of the vertebrate brain: Forebrain, Midbrain, Hindbrain
  • Variation of brain sizes or subregions across animals
  • Somatotopic map

  
• Function of the Nervous System

  • Homeostatic control system
  • Regulates physiological processes
  • Coordinates behaviour
  • Processes and stores information
  • Consists of structures and organs that facilitate electrical and chemical communication in the body
• Autonomic nervous system


  • Sympathetic (fight or flight response)
  • Parasympathetic (rest and digest response)
  • Target the same organs, but have opposite effects

  
• Central Nervous System


  • Consists of brain and spine
  • Brains are the result of selection for centralization of the nervous system
  • Receives sensory signals and determines appropriate response
  • Stores memory
  • Carries out thought

  
• Spinal Cord


  • Transmits signals from the sensory organs, muscles and glands to the brain
  • Controls reflexive responses
  • Conveys signals from the rest of the body

  
• Spine: structure


  • Spinal cord is protected by the vertebrae
  • Gray matter contains cell bodies (soma); white matter contains myelinated fibers
  • PNS nerves extend outside of the vertebrae
• There are about 3 million miles of axons in the human brain
• Information travels in the nerves at speeds up to 268 miles per hour
• Four principles of functional organization apply to most vertebrate brains


  • Brain function is somewhat localized
  • Brains have maps
  • Size matters
  • Vertebrate brain evolution has involved repeated expansion of forebrain area

  
• Hindbrain


  • Carries out the most basic functions
  • Cerebellum, Pons, and Medulla
  • Responsible for basic, reflexive functions
• Midbrain


  • Helps orient eye and body movements to visual and auditory stimuli
  • Coordination of visual and auditory reflexes
  • Larger in animals that depend on these stimuli eg fish, amphibians
• Forebrain


  • Largest, most complicated and most advanced brain division
  • Cerebrum, Thalamus, Hypothalamus
  • Associated with complex thought and behaviors: ability to concentrate, elaboration of thought, judgment and inhibition

  
• Forebrain - Thalamus and Hypothalamus

  • Thalamus: Processes sensory information before it reaches the cerebral cortex
  • Hypothalamus: Controls complex behaviors such as eating, drinking and sexual activity, signals to the pituitary gland
• Forebrain - Cortex


  • The outermost layer of the cerebrum
  • Various areas control sensory processing, motor control, thought, memory
  • Wiring is plastic: e.g. people blind from birth, use parts of the visual cortex to process auditory signals
  • 4 lobes

  
• Olfaction


  • Smell is the strongest sense tied to memory
  • Olfaction is the only sense that is directly connected to the cortex, via the olfactory bulb
  • Not filtered by the midbrain and thalamus
  • Smells are processed by structures in the limbic system – parts of our brain that evoke emotion and memory
• Observation 1: The brain has specialized regions

  • Hindbrain carries out the most basic functions
  • Midbrain coordinates signals
  • Forebrain processes signals, stores memories, creates thought (Complex processes)

  
• Observation 2: The exterior covering (cortex) of the brain is wrinkled, which increases surface area


  • Different animals have different folding of the cerebrum = more surface area
  • More recently evolved animals have a larger proportion of the brain taken up by the cerebral cortex

  
• Observation 3: The brain is divided into 2 hemispheres

  • Right and left hemispheres
  • Connected by the corpus callosum

  
• Split brain patients


  • Damage to the Corpus Callosum results in two independent brains in one skull
  • Split brain patients allowed researchers to discover "hemispheric specialization"

  
• Left Brain


  • Controls Right Side of Body
  • Right Side Visual Field
  • Speaking
  • Reading
  • Logical Thinking
  • Analytical Skills
  • Sequential Processing
• Right Brain


  • Controls Left Side of Body
  • Left Side Visual Field
  • Spatial Processing
  • Facial Recognition
  • Music
  • Emotional Expression
  • Holistic Thinking
• Somatotopic map


  • Homunculus – little person
  • The amount of cortex that is devoted to each body part is not equally distributed
  • Larger areas are devoted to touch in the most sensitive parts of the body such as lips and hands
  • Smaller areas are devoted to touch in less sensitive parts of the body such as the back and abdomen
• How does Hind-, mid- and Fore-brain size differ in animals? Size matters

  • Larger brain = more complex integration
  • Bigger does not mean smarter
• The brain of Albert Einstein weighed 2.7 lbs. This is below the average brain weight of 3 lbs
• The brain of an elephant weighs about 4.78 kg (10.5 lb). An adult human brain weighs about 1.4 kg (3 lb)
• What is mind?


  • Many traditions, including psychology, separate "brain" from "mind"
  • What we perceive as "mind" (thought, will, self-perception) does produce evidence of brain activity in brain scans
  • "Brain" influences "mind" is well-established; but some evidence shows "mind" can influence "brain"; as cognitive therapy for depression can physically change the brain
• Is Psychology a science?
• Amniota


  • Lineage with this reproductive pattern – nonavian reptiles, birds, mammals
  • Presence of an amnion (a type of extraembryonic membrane)
  • Different types of skulls
• Aves


  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Class: Aves
  • 10,500 species (2nd largest # of vertebrate species after fishes)
  • 40 Orders (9 shown: Archaeornithes (extinct), Paleognathae ("Old jaw"), Neognathae ("New jaw"))
• Archaeopteryx


  • Discovered in 1861, the fossil demonstrated the phylogenetic relatedness of birds and theropod dinosaurs
  • Skull resembled modern birds but had teeth rather than a beak
  • Skeleton was reptilian with clawed fingers, abdominal ribs, and a long bony tail
  • Feathers were unmistakably imprinted along wings
• Classification of Modern Birds

  • Paleognathae (old jaw) are large, flightless, ostrichlike birds and kiwis (ratite birds)
  • Neognathae (new jaw) are all other birds
• Uniformity of Structures Across All Birds

  • Feathers – no other animal has feathers
  • All birds have forelimbs modified as wings, although not all are capable of flight
  • All birds have hindlimbs adapted for walking, swimming or perching
  • All birds have keratinized beaks
  • All birds lay eggs
• Characteristics of modern birds did not appear all at once

  • Transitional forms had a mixture of derived and ancestral traits
  • This is called mosaic evolution
  • Evolutionary change in one or more body parts without simultaneous changes in other parts e.g. evolution of birds from dinosaurs
• Feathers


  • Feathers preceded flight
  • A bird's entire anatomy is designed around flight
  • Feathers are very lightweight yet have remarkable toughness and tensile strength
  • Most feathers are vaned feathers that cover and streamline a bird's body, called contour feathers
  • Down feathers (insulation)
  • Some feathers function in sensation
• Contour Feathers


  • Consist of hollow quill (calamus) emerging from skin follicle and a shaft (rachis) bearing numerous barbs
  • Up to several hundred barbs are arranged to form a flat, webbed surface, the vane
  • Each barb resembles a miniature feather
  • Numerous parallel filaments (barbules) spread laterally
  • Barbules from two neighboring barbs overlap and zip together with tiny hooks
• Feathers are Homologous to Reptile Scales

  • A feather develops from an epidermal elevation overlying a nourishing dermal core
  • Rather than flattening like a scale, a feather bud rolls into a hollow cylinder and sinks into the follicle from which it is growing
  • During growth, pigments (lipochromes and melanin) are added
  • Near the end of its growth, the soft shaft and barbs transform into hard structures of keratin called the protective sheath
  • Feathers are made of up dead cells, or cell products, like hair
  • Feathers are lost evenly in pairs on each side to maintain balance
• Skeleton: Pneumatized Bone


  • Modern birds have light, delicate bones laced with air cavities
  • Termed pneumatized bones, it is light but strong
  • Total weight of a bird's feathers may outweigh skeleton
  • Pigeon skull: 0.21% of body weight
  • Rat skull: 1.25% of body weight
  • Pneumatized bones: Stiffened cross-struts and air spaces replace bone marrow, Thin walls, Remarkably light and strong
• The skeleton is adapted to flight


  • Locomotor muscles of wings are relatively massive to meet demands of flight
  • Largest is the pectoralis muscle (depress the wing in flight and are attached to the sternum keel)
  • Supracoracoideus muscle (raises the wing, is also attached to the sternum keel, lays under the pectoralis muscles)
• Feathers


  • Made of up dead cells, or cell products, like hair
  • Lost evenly in pairs on each side to maintain balance