Brain and Nervous System

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Biological Approach:

1/12/2011 A Presentation by Sanjay Singh 1 Biological Approach Brain & Nervous System

Previous Year Questions:

1/12/2011 A Presentation by Sanjay Singh 2 Previous Year Questions Describe the major divisions of Central Nervous System and give an account of their functions or Examine the mind body relation influencing the behaviour (2007) Describe features and functions of various parts of Nervous System or discuss the nature of heredity vs. environment controversy. (2006)

Neurons:

1/12/2011 A Presentation by Sanjay Singh 3 Neurons A Neuron refers to a nerve cell. It is the basic structural & functional unit of nervous system. A normal human brain contains billions of neurons serving a variety of functions. Neurons keep on growing and decaying. In an unborn baby neurons can grow @ 250, 000/ minute, however around half of them die before the baby is born. The information in nervous system travels thro’ a chemical liquid called neurotransmitter found in the gap between two neurons.

Structure of a Neuron:

1/12/2011 A Presentation by Sanjay Singh 4 Structure of a Neuron

Nervous System: Major Divisions:

1/12/2011 A Presentation by Sanjay Singh 5 Nervous System: Major Divisions Nervous System Central Nervous System Peripheral Nervous System Brain Spinal Cord Somatic (Voluntary) Autonomic (Involuntary) Sympathetic (Trouble Shooter) Para Sympathetic (House Keeping) Forebrain Midbrain Hindbrain

The Human Brain:

1/12/2011 A Presentation by Sanjay Singh 6 The Human Brain Two Hemispheres: Left & Right connected by Corpus Callosum Outer covering of brain is called Cortex The three major divisions of brain- Brain Stem (an extension of spinal cord) & Cerebellum; Limbic System (maintains homeostasis) ; cerebral cortex (performs psychological functions like thinking, emotions, etc.)

The Opposing functions of Two Brain Hemispheres:

1/12/2011 A Presentation by Sanjay Singh 7 The Opposing functions of Two Brain Hemispheres

Dysfunctions of Brain:

1/12/2011 A Presentation by Sanjay Singh 8 Dysfunctions of Brain

Basic Structure of Human Brain:

1/12/2011 A Presentation by Sanjay Singh 9 Basic Structure of Human Brain

Functions of Brain:

1/12/2011 A Presentation by Sanjay Singh 10 Functions of Brain Functions of Brain Stem & Cerebellum It is the center of basic life support- breathing, heartbeat, waking, sleeping & dreaming It consists of structures like Pons, Thalamus & Medulla Oblongata Pons are involved in dreaming & waking Thalamus is just situated above the brain stem and acts like a “relay station” that sends incoming sensory stimulus to the appropriate cortex area for processing. There is thalamus in each hemisphere both acting in unison. Cerebellum: coordinates movement, manages posture & maintains equilibrium. It also stores memory of movement patterns so that we do not have to concentrate on how to walk, dance or ride a bicycle.

Functions of Brain…continued:

1/12/2011 A Presentation by Sanjay Singh 11 Functions of Brain…continued Functions of Limbic System: It helps in maintaining internal homeostasis by regulating body temperature, blood pressure, blood sugar level, etc. It consists of Hippocampus, amygdala & hypothalamus Hippocampus is the largest part of Limbic system and plays important role in memory especially long term memory. Amygdala plays important role in aggression. Hypothalamus is the smallest structure of limbic system and it plays important role emotional behaviour, eating, drinking, and homeostasis.

Functions of Cerebral Cortex/ Cerebrum:

1/12/2011 A Presentation by Sanjay Singh 12 Functions of Cerebral Cortex/ Cerebrum Cerebral cortex maintains higher order psychological function. These functions are divided among four major lobes as shown below- Lobe Functions Frontal Thinking, reasoning, Planning, Problem Solving, personality, emotions, etc Occipital Vision Parietal Control & management of incoming sensory information Temporal Language , hearing , speech

Four Main Lobes of Brain:

1/12/2011 A Presentation by Sanjay Singh 13 Four Main Lobes of Brain

…And Functions of these Lobes:

1/12/2011 A Presentation by Sanjay Singh 14 …And Functions of these Lobes

Functions of Spinal Cord:

1/12/2011 A Presentation by Sanjay Singh 15 Functions of Spinal Cord Transmitting information (about touch, pain, temperature, etc.) to the brain, hence called “information pathway to brain” Reflex Reaction: Alerting against dangerous stimuli Damage to spinal cord may result in paralysis to legs or trunks.

Functions of Peripheral Nervous System:

1/12/2011 A Presentation by Sanjay Singh 16 Functions of Peripheral Nervous System Divisions Functions Somatic Nervous System (Voluntary) Connects voluntary muscles with CNS. E.g., When you order a pizza or listen to my lectures your somatic nervous system is active Autonomic Nervous System (Involuntary) Connects involuntary muscles with CNS. E.g., our digestion process, hormonal secretion, etc. Sympathetic Part Prepares body for using energy as in vigorous physical exercise. When we exercise it gets activated and increases our heartbeat, increases flow of blood in body and releases sugar in blood to give us energy needed for physical activity. Para-Sympathetic Part It operates in opposite manner to sympathetic part, i.e., it operates to conserve energy. It slows heartbeat, lowers blood pressure & diverts blood away from skeletal muscles (= muscles of arms & legs).

Interaction of Mind & Body:

1/12/2011 A Presentation by Sanjay Singh 17 Interaction of Mind & Body The Mind-Body Problem: One of the most persisting problems of Philosophy & Psychology concerning the nature of relationship between mind & body. French Philosopher René Descartes in his works Description of the Human Body (1640) & Passions of the Soul (1649) discusses this problem in detail

Three views regarding interaction of mind & body:

1/12/2011 A Presentation by Sanjay Singh 18 Three views regarding interaction of mind & body Psycho- Physical Parallelism Or Dualism Psycho- Physical Identicalism Or Monism Psycho- Physical Interactionalism Or Interactionism

Heredity Vs Environmental Influences on Behavior:

1/12/2011 A Presentation by Sanjay Singh 19 Heredity Vs Environmental Influences on Behavior Another controversial issue in psychology that what determines our behaviour: heredity (genes) or environment? This is also known as the nature-nurture controversy that what determines our behaviour: nature (our inherited biological characteristics) or nurture (or our acquired social characteristics)? Do you believe that: “a tendency to throw objects is inherited by boys” Success runs in families. Males are poor in understanding & expressing emotions than females. Males are generally better than females in mathematics & engineering subjects. The two twin brothers will have same temperament irrespective of where they live.

Twin Studies & Adoption Studies supporting Nature:

1/12/2011 A Presentation by Sanjay Singh 20 Twin Studies & Adoption Studies supporting Nature Studies have shown that genetic factors do play a role in mental disorders like schizophrenia, autistic disorders, depression, phobias, etc. ( Merkelbach et al., 1996 ) Adoption studies show that identical twins show remarkable degree of similarity in everything from various aspects of their personality to attitude and values, hobbies, career choices, and even job satisfaction ( Hershberger et al., 1994; Lykken et al., 1992 )

Twin Studies & Adoption Studies supporting Nurture:

1/12/2011 A Presentation by Sanjay Singh 21 Twin Studies & Adoption Studies supporting Nurture Studies on shyness indicate that although shyness is largely determined by genetic factors but parents play a key role in determining whether or to what extent their children actually become shy. Shy children whose parents encourage them to try new things become less shy while those whose parents do not make this effort often become painfully shy and withdrawn ( Kagan & Snidman, 1991 ).

Case Study: 'Wolf children of India, the study of Kamala & Amala by P.C. Squires, 1927. :

1/12/2011 A Presentation by Sanjay Singh 22 Case Study: 'Wolf children of India, the study of Kamala & Amala by P.C. Squires, 1927. Kamala and Amala are two of the most interesting cases relevant to nature nurture controversy. They were about 18 months (Amala) and eight years old (Kamala) when they were found together in a wolves' den in Midnapore, WB, India. However, it is believed that they were not sisters, but were abandoned — or taken by wolves — some years apart. Eight years ago I was on tour of my villages. One evening one of my people said, "There are ghosts in the woods. We are much afraid." So I watched the next night. Just before sundown, three old wolves came up out of a hole. Then two cubs and at last a queer human-like animal. The man with me wanted to shoot. But I forbade him. No one would go near the den so I got men from seven miles distant who knew not of the ghosts. They dug out the den. Two wolves ran off, the third was killed with an arrow. She being the mother refused to run away. Down in the bottom of the den cuddled up with two furry cubs were two queer little girls. Against their desires we gathered them up and brought them home. Whether they were illegitimate and thrown away or torn from their mother's cottage door by the wolves, we do not know. For the first four or five years they ran about on their hands and knees. After being compelled to, they could stand but not run. The younger never learned to talk, could only grunt and growl. The older one lived to be a little over six years of age with the mentality of a two and one-half year old child. She learned to talk and developed a vocabulary of about one hundred words. They never asked questions. Their jaws were large and square supposedly from gnawing bones. Both have been dead for some time.