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JOURNEY TO THE CENTER OF THE BRAIN Each region of the brain has distinct structural and functional characteristics that shape how the brain functions. Guiding Questions What are the major regions of the brain? What are the major functions of each region of the brain? How can damage to the brain affect the brain’s functions? CNS vs. PNS Central Nervous System (CNS) Brain and spinal cord Relays and processes messages from senses and organs CNS vs. PNS Peripheral Nervous System Everything Ex: else Neurons Interacts with environment Carries messages between organs and CNS THE BRAIN! Anatomy of the Brain The vertebrate brain has three main parts which evolved in different stages A vertebrate is any animal that contains a spinal cord (Vertebrata) Forebrain – Newest part of the brain; found only in mammals Midbrain – found in vertebrates only Hindbrain – Oldest part of the brain (found in reptiles…so we know it’s really old!) What does it do? Forebrain – the outer layer of the cerebrum, which performs all of the “higher functions” of the brain The forebrain has two main components Forebrain Cerebral Cortex 1. 2. 3. Planning Thinking and reasoning Sensory processing Limbic System 1. Emotional/sensory processing 2. Learning and memory “The new kid on the block” THE NEOCORTEX (PART OF THE CEREBRAL CORTEX) The Neocortex 1. 2. 3. 4. The Neocortex is the newest part of the cerebral cortex. Again this deals with higher levels functions. It is divided into four lobes or regions: Frontal lobe Parietal lobe Temporal lobe Occipital lobe Cerebellum Brain stem These make up the Neocortex Hindbrain Different lobes do different jobs The four lobes process different types of information Frontal lobe – processes information relayed from “lower” brain areas concerned with movement and thinking. The frontal lobe plans is also an integral part of personality. Parietal lobe – higher processing of sensory information from other brain areas and the spinal cord. Deals with direction, and orientation in a 3-dimensional space. *Proprioception – having a sense of your own body movements Temporal lobe – processes auditory information. Concerned with the production of speech and understanding spoken language (and music). Also uses emotional cues of the underlying limbic system to deal with facial recognition or “face centers.” Occipital lobe – Visual processing and perception. Damage to the brain The case of Phineas Gage 25-year old foreman who suffered severe brain trauma when a piece of iron penetrated his skull He survived the injury and could even speak shortly after the accident! However, profound changes occurred in his personality and demeanor Once a highly-respected and responsible citizen, Gage now became “irreverent, profane, and unreliable”. He no longer followed through with plans and had little respect for his friends and colleagues. “He was no longer Gage” Discussion Question: Phineas Gage What part of Gage’s brain was destroyed by the iron bar? THE BRAIN STEM AND CEREBELLUM Hindbrain The Brain Stem In humans, the brain controls the basic functions of the body Brain stem – controls respiration (breathing), heart beat, digestion and circadian rhythm (sleep cycle) The Brain Stem is made up of the Pons (top) and the Medulla Oblongata (bottom) Evolved hundreds of millions (100,000,000) years ago and is the “oldest”, most primitive part of the brain Amazingly, chickens can survive without a head, as long as their brainstem is still intact! Brainstem = Pons + Medulla Oblongata) Discussion Question: Chickens Why was the chicken able to survive for so long without a head? The Cerebellum The Cerebellum deals with balance, coordination, and certain forms of learning Human cerebellum Procedural learning – motor skills such as riding a bike, driving, etc. Relatively small in the human brain compared to other animals such as the rat Considered to be part of the hindbrain Rat cerebellum The Emotional Brain THE LIMBIC SYSTEM What is the limbic system? Underneath the neocortex Deals with homeostasis, digestion, emotions, behavior and memory Major parts include: Diencephalon (hypothalamus, thalamus) Amygdala Hippocampus Hypothalamus Function: Regulates the autonomic (automatic) nervous system Homeostasis (i.e. hunger, thirst, temperature, pain, pleasure, sex drive and aggression) How it works: stress stimulates the hypothalamus-pituitary-adrenal (HPA) axis to release cortisol Cortisol is a steroid hormone It regulates breathing, pulse, blood pressure and arousal in response to stress Hippocampus Lies in the medial temporal lobe and consists of many packed neurons Function: Converts “short-term” memories into long-term memories May deal with memory/smell When damaged: Alzheimer's, hypoxia (lack of oxygyen), and epilepsy (action potential overload) Inability to form new long-term memories Amygdala Found on the lower end of the hippocampus near the thalamus Function: Emotional learning – processes memories of emotional events Stimulated by fear, aggression When damaged: Become calm and indifferent A little boy named Albert was fond of white animals, including rats. One day, James Watson made a loud, unpleasant noise with a hammer while Albert was looking at a white rat. He cried and seemed very frightened. Now every time Albert sees a rat, even when there is no noise, he starts to cry. Albert’s amygdala has learned to associate white rats with loud noises. This is called “fear conditioning”