1 Introduction to the nervous System

2 Development of the Nervous System Formation of neurons – neurogenesis- largely prenatal Majority of cells develop in first 3 months gestation - up to 150,000 cells per minute easily disrupted by chemicals and radiation Majority of cells develop in first 3 months gestation - up to 150,000 cells per minute easily disrupted by chemicals and radiation Migration pre and post natal Cells move from where they were formed to their target area Cells move from where they were formed to their target area They move either toward or away from chemicals released by areas of the brain They move either toward or away from chemicals released by areas of the brain Interconnections develop – largely postnatal Programmed cell death

3 Divisions of the nervous system Central nervous system - encased in bone Spinal cord Spinal cord brain brain Peripheral nervous system – everything else Somatic nervous system – voluntary control Somatic nervous system – voluntary control Sensory nerves Motor nerves Autonomic nervous system – no conscious control Autonomic nervous system – no conscious control Sympathetic nervous system – fight or flight response Parasympathetic nervous system -

4 The spinal cord

5 Function of the spinal cord White matter – nerve fibers running to and from the brain Gray matter – neurons and synapses, mediates reflexes Dorsa horn – sensory Ventral horn - motor

6 The Non-Mammalian Brain

7 Mammal Brains

8 The Human Brain

9 Hindbrain Medulla – involved with autonomic system –regulating breathing and vomiting, etc. Reticular activating and raphe system – activates the brain maintaining arousal or reduces arousal for sleep Locus coeruleus – mood control and alerting response Cerebellum – coordination of voluntary movements, eye saccades, and simple learning

10 Midbrain Contains centres for the receipt and integration of several types of sensory information The superior and inferior colliculi are part of the visual and auditory systems The reticular formation is the core of the brainstem running through the mid-brain, pons and medulla Some researchers have speculated that the reticular formation controls approximately 25 specific behaviors, including sleeping, walking, eating, urination, defecation, and sexual activity

11 Hindbrain and Midbrain

12 Limbic System Hypothalamus Controls eating drinking, sexual, etc. behaviorsHippocampus Formation of new memoriesSeptum Emotion and emotional memoriesAmygdala Implements aggressive behavior Active in fear conditioning

13 Cerebrum Two hemispheres Major coordinating centers for from which sensory information and accompanying motor actions originate The surface of the cerebrum is known as the cerebral cortex

14 Cortex Composed of grey matter Has many folds that increase surface area (called fissures) Posterior and central areas primarily concerned with sensory and motor functions Frontal lobe – inhibition of behaviors, expression of emotion, availability of rewards Prefrontal areas Orbitofrontal – learning reward associations Prefrontal working memory and thinking Dorsolateral – maintenance of attentional demands of a task Anterior cingulate – mediates attention, inhibition of dominant behaviors

15 The Cortex

16 Occipital Lobe Sensory areas associated with vision Association areas interpret visual information

17 Temporal Lobe Sensory areas associated with vision and hearing Association areas have been linked to memory and interpretation of sensory information

18 Parietal Lobe Sensory areas associated with touch and temperature awareness Association areas have been linked to emotions and interpreting speech