1. Integrative Function of the Nervous System

2. Lecture Overview
Overview of the Brain
Neurotransmitters
The Brain

3. The Nervous System

4. Central Nervous System
The CNS is composed of the brain and spinal cord
Spinal cord connects the brain with the PNS
Spinal cord is comprised of cell bodies and axons that carry messages
Afferent: toward the brain (sensory function)
Efferent: away from the brain (motor function)

5. Peripheral Nervous System
The Peripheral Nervous System (PNS) includes all nerves outside the brain and spinal cord
Somatic NS carries sensory messages to brain and motor commands to the muscles
Autonomic NS regulates automatic body functions (such as heart rate, breathing)
Sympathetic: “Fight or Flight”
Parasympathetic: dominant when relaxed

6. The Autonomic Nervous System

7. The Spinal Cord

8. Myelin
Myelin is a fatty, waxy substance coating the axon of some neurons.
Functions:
Speeds neurotransmission
Insulates neurons from each other
Makes neurotransmission more efficient

9. Synapse
The synapse is the junction between an axon terminal and an adjacent dendrite or cell body.
Neurotransmitter (NT) molecules are released from the axon terminal into the synapse when the action potential arrives at the axon terminal.

10. The Synapse Synthesis of neurotransmitter (NT)
Storage and transport of NT within vesicles
NT Release
Activation of postsynaptic receptors
Termination of transmitter effect (e.g. reuptake)

11. Neurotransmitters Serotonin Acetylcholine Dopamine Norepinephrine
GABA
Endorphins

12. Psychoactive Drugs
Psychoactive drugs affect the nervous system to alter mood, emotion, and thought
Psychoactive drugs act by:
Increasing or decreasing release of neurotransmitters
Stimulating or blocking receptor sites

13. Psychoactive Drugs Agonists enhance neurotransmitter function
Antagonists block neurotransmitter function

14. Midline Brain View

15. Brainstem Brainstem is a primitive portion of brain
Pons: involved in respiration, sleep regulation, dreaming
Medulla: involved in life support functions such as respiration and heart rate
Reticular activating system is an arousal system within the brainstem

16. Subcortical Brain Areas
Corpus callosum: band of axons that interconnects the hemispheres
Thalamus: sensory relay area
Limbic system: involved in emotionality
Hypothalamus: feeding, fleeing, mating, fighting, homeostasis
Cerebellum: involved in motor control
Subcortical Brain Areas

17. HYPOTHALAMIC REGULATION OF PHYSIOLOGIC FUNCTIONS
Water and electrolyte balance
Temperature regulation
Activation of sympathetic nervous system
Thirst and regulation of drinking
Hunger, satiety and regulation of feeding
Regulation of sexual behavior
Regulation of circadian rhythms
Pituitary hormone secretion

18. HYPOTHALAMUS CONTAINS “BIOLOGIC CLOCK”
Hypothalamus plays a major role in regulating biologic rhythms
Rhythms persist in absence of time cues
Circadian or diurnal rhythms repeat daily
External signals of light and darkness serve to entrain the internal clock to a 24 hour day
Biologic clock is located in the suprachiasmatic nucleus
Input is received from the eye by the retinohypothalamic tract of the optic nerve

20. Limbic System The fornix is a C-shaped bundle of
fibres (axons) in the brain, and
carries signals from the hippocampus
to the mammillary bodies and
septal nuclei.
The amygdala is an almond-shaped group of nuclei located deep within the medial temporal lobes of the brain in complex vertebrates, including humans. Primary role in the processing and memory of emotional reactions and considered part of the limbic system.
The hippocampus plays important roles in long-term memory and spatial navigation. Like the cerebral cortex, with which it is closely associated, it is a paired structure, with mirror-image halves in the left and right sides of the brain.

21. LIMBIC SYSTEM FUNCTIONS
BRAIN REWARD SYSTEMS
Electrical stimulation of various sites in the limbic system produces either pleasurable (rewarding) or unpleasant (aversive) feelings
Dopaminergic neurons play a major role in mediating reward
AGGRESSION
Stimulation of sites in hypothalamus and amygdala elicits a fight or flight reaction and postures of rage and aggression
Severing the cortical connections to the limbic system results in permanent rage postures and aggressiveness
SEXUAL ACTIVITY
Limbic system in general coordinates sex drive and mating behavior
Higher cortical centers exert more or less overriding influences

22. MEMORY AND LEARNING
Most likely sites are large association areas of the cerebral cortex working in association with subcortical structures as hippocampus and amygdala
Prefrontal cortex is important for coordinating formation of memory
Hippocampus is important in consolidating memory
Association cortices are important in storing memories
Short term memory
Product of working memory-prefrontal
cortex
Long term memory
Involves limbic system input

23. Cerebral Cortex Cortex refers to the outer covering of the brain
Consists of left and right hemispheres
Cortex is divided into lobes
Frontal: Self-awareness, planning, voluntary movement, emotional control, speech, working memory
Parietal: Body sensations
Occipital: Vision
Temporal: Hearing, language comprehension

24. Cortical Lobes

25. Summary of Hemispheric Specializations

26. Motor and Somatosensory Cortex

27. Split-Brain Research
When a split-brain patient is asked to stare straight ahead while a photo of a fork is flashed to his left visual field, he cannot name it.

28. Split-Brain Research