(Chapter 3) The Developing Brain - Social Brain Structures & Functions

(Chapter 3) The Developing Brain - Social Brain Structures & Functions

1. 1. Plastic patterns of Neural Organization

   • The brain is plastic
     • Neural tissue has the capacity to adapt to the world by changing how its functions are organized.
       • A slower rate of maturation favors larger brains: Enriched environment is associated with growth of existing brain cells and thus an increase in brain size
         • The nervous system’s potential for physical or chemical change that enhances its adaptability to environmental change and its ability to compensate for injury.
   • The pattern of glucose merabolism
     • Neonatal period: Low in most of the Cerebral Cortes, but high metabolic activity in the Limbic System - emotional development
     • Frontal Cortex: the last brain area to display an increase in glucose activity (%6-8 moths)
   • Phenotypic Plasticity
     • Individual genotype (genetic makeup) interacts with the environment to elicit a specific phenotype from a large genetic repertoire of possibilities
   • Critical and sensitive periods
     • Period of exuberant neural growth
     • Critical Period
       • A time when a particular part of the body is most easily influenced or vulnerable to the lack of stimulation or to environmental effects
       • Prenatal exposure to substance, exposure to light during the first few months of life (at least 6 months)
     • Sensitive Period
       • The broad windows of opportunity for certain types of learning; less precise and a longer time period compared to critical period.
       • First 18 months: the right hemisphere has high growth rates
         • Sensory and motor capabilities. Basic structure of attachment & emotional regulation
       • The left hemisphere: slow growth, some reserved for later language development
       • At the end of the 1st year: Corpus callosum begins to develop - integration of the hemispheres
         • During the 2nd year: LH - Language development. Locomotion allow the exploration of social & physical world

2. 2. Overview of Human Brain Function and Structure

   • The brain primary function is to produce behavior (movement)
     • To do so it must: a) Receive info (stimulus) @ the world, objects around us. Otherwise the brain can't produce an appropriate response
       • Organs of the nervous system receive info from the world & converted into biological activity that produces perception, or subjective experiences of reality
         • PLASTIC: neural tissue has the capacity to adapt to the world by changing how its functions are organized

3. 3. Functional Organization of the Nervous System

   • 1.NEURONS: Basic units of the NS.
     • 2. GLIAL CELLS:
       • Role in construction , organization & maintenance of neural system
         • Aprox 100 billion
     • Aprx 80 billion
       • Myelination: Indicator of maturity of a neural network
   • 1. Central Nervous System (CNS)
     • 2. Pheripheral Nervous System (PNS)
       • Somatic Nervous system
         • Transmit sensation, produces movement
         • Cranial Nerves & Spinal Nerves
       • Automatic NS
         • Balance Internal functions - For rest and digest
           • Sympathetic division (Arousing)
             • Parasympathetic division (calming)
       • Enteric NS
         • Controls the gut
         • mostly operates autonomously
     • Brain & Spinal Cord
     • Direction of neural info
       • Afferent
       • Efferent

4. 4. Surface features of the brain

   • Cerebrum
     • Cerebellum: Little brain
       • Brainstem
         • Central structures of the brain, including the hindbrain, midbrain, thalamus, and hypothalamus, responsible for most unconscious behavior
       • Involves coordination of motor & maybe other mental process
     • Major structure of the forebrain, consisting of two virtually identi cal left and right hemispheres
   • Cerebral circulation
     • Surface boold vessels
       • Anterior, Middle & Posterior arteries
       • Stroke
         • Result of severe interruption of blood flow
         • Because the brain connections are crossed Left Hemisphere affects sensation & movement on the right side of the body

5. 5. Internal features of the brain

   • Macro
     • Grey Matter
       • Composed of cell bodies & blood vesels
     • White Matter
       • Areas of the nervous system rich in fat-sheathed neural axons
     • Corpus Callosum
       • Fiber system connecting the 2 cerebral hemispheres
         • Contains @ 200 million nerves
   • Four ventricles
     • Cavities in the brain that contain cerebrospinal fluid
       • 2 Lateral ventricles (right & left) Third ventricle & Four ventricle
       • CBS Fluid: cushions the brain & meningitis

6. Brain through life

   • 6. The teenage brain
     • Goes through a process of selection and reorganization of neural networks from the onset of puberty into the early 20s
       • Loss of the overall number of neurons
         • Faster & more efficient info
           • # of myelinated fibers connecting functional neural networks
       • Social transitions (creation of flia & peers)
       • Change in reward circuitry: risk taking decisions - poor decision making abilities
   • 7. Adult brain
     • Prefrontal cortex continues to develop
       • > pruning of grey matter & increase white matter connectivity
         • Coupled with decreasing hormonal and emotional influences
           • lateral specialization in the frontal lobe peaks- less efficient stuff gets eliminated (speed over deeper consideration of problems)
             • # of neurons within the cortex continues to decrease: adaptation to new envinroments/processing capabilities
   • 8. Aging brain
     • Neural networks are more vulnerable
       • The dorsal and lateral areas of the prefrontal lobe show the earliest signs of aging
         • Structural changes in the frontal lobe + shrinkage in lower brain nuclei (involved in attentional and memory functions)
           • The orbital medial prefrontal cortex systems continue to develop – reflects the retention and improvement of social judgement and empathy

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