Psychobiology

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Psychobiology

• Prof. Ismail Youssef

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• Every think should be made as simple as possible,
  but not simpler
• Einstein

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• Study the role of physiology in the regulation
  and execution of behavior
• THE BRAIN
• -Look like a lump of porridge
• -Consistency of blancmange
• -About 1.4 Kgm
• -It contain 10-100 billion of nerve cell
• -Same no. of supporting cell

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• -Nerve cells differ as regards
• Shape
• Size
• Kind of chemical they produced
• -Nerve cells are organized in clusters that
  communicate with each other and connected to
  other circuits

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• DORSAL (Superior)
• Caudal
  Rostral
• (Posterior)
  (Anterior)
• VENTRAL(Inferior)

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• Central Nervous System (CNS)
• - Brain
• -Spinal cord
• Peripheral nervous system(PNS)
• The nerves which are attached to the spinal cord
  and the base of the brain

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• Brain-Cerebral Hemispheres
• -Cerebellum
• -Brain Stem
• CNS is encased in the skullvertebrae
• Enclosed by a three membranes called meninges (
  pleural of meninx )
• They float in a fluid called Cerebro Spinal Fluid
  ( C S F )

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• The surface of C H covered by C C
• (cortex rind ), 3 mm ( grey matter )
• In this structure
• -Perception take place
• - Memories are stored
• - Plans are formulated executed
• The nerve cells in CC are connected to other
  parts of the brain by a layer of nerve fibers
  called ( white matter )

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• The human CC is wrinkled full of bulges (gyri ),
  gyrus , and grooves ( sulci ), sulcus
• The large sulcus is called fissure
• (We have 2 lateral and central fissures(

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• Brain stem Primitive region in Amphibion, it
  controls automatic behaviors such as (swallowing
  and breathing)
• Cerebral hemisphere largest and most recently
  developed part of human brain
• Cerebellum attached to the back of brain stem,
  looks like miniature version of C.H., its primary
  function is to control and coordinate movement.

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• Peripheral nervous system PNS
• Connect CNS with sense organs
• muscles
• glands
• -some are attached to the spinal cord.
• -others are attached directly to the brain
  (cranial nerve)

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• Other cells (Glial cells) (G glue)
• -Mechanical support
• -Protection
• -Guide development
• -manufacturing chemicals
• -Brains immune system

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• 4 principle parts of neuron
• 1-Somma cell body , largest part of neuron
• 2-Dentrites (Dentron G tree)
• receive messages and transmit the information
  to the soma
• 3-nerve fiber (axon)
• carries messages away from the soma towards
  the cell with which the neuron communicate (the
  firing of an axon)
• brief changes in the electric charge of the axon

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• 4-the terminal button located at the ends of the
  branches of the axon, terminal button secrete a
  chemical called a transmitter substance whenever
  the (fire) of the axon travel down
  (neurotransmitter)
• Most drugs affect the chemical transmission of
  messages between cells.

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• Myelination
• Axon esp. long ones are insulated with substance
  called myelin (protein and fat) produced by
  special cells wrap themselves around the axon.
• Myelin sheath is important in immunological
  diseases, in which the broken of myelin sheath is
  attacked.
• -Patches of hardened, damaged tissue (multiple
  sclerosis)
• Maturation of CNS occurs when myelination is
  completed

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• Action potential (firing)
• -It is not like electricity travel through a wire
• -axon transmits information at a rate less than
  100 meters /second
• 70 mV
• -ve
• _____________
• -Opening of Na channel to go in, after a brief
  time opening of Na channel to go out (rest
  position)

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• Synapsis
• Neurons communicate with other neurons by means
  of synapses.
• Synapse in the conjunction of a terminal button
  of one neuron and the membrane of another
  dendrites of neuron, muscle or gland cell
• Terminal button belong to the presynaptic neuron(
  the neuron that sends the messages)
• The neuron that receives the message detects the
  transmitter substance) is called the postsynaptic
  neuron

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• Excitation Inhibition
• 2 TYPES
• -Excitatory Post Synaptic Potential(EPSP)
• Increase the likely of postsynaptic to fire
• -Inhibitory Post Synaptic Potential(IPSP)
  Synaptic cleft-fluid filled space-between the
  terminal button and the membrane of the post
  synaptic neuron (receptor molecule,protein)lead
  to opening ion channel
• EX.IN.synapses permit ions to enter or to leave
  the neuron

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• EX.IN. produced by a synapse is short-lived, the
  effect is terminated by reuptake process
• The rate of reuptake determine how prolonged the
  effects of the chemical on the postsynaptic
  neuron will be.

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• Simple neuron circuit
• The interconnections of neurons provide us with
  the capacities for
• -Perception
• -Decision making
• -Memory
• -and action

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• Simple withdrawal reflex
• which is triggered by a noxious stimulus such
  as contact with a hot object.
• It require 3 types of neuron
• 1)Sensory neuron, detect and convey the
  information to the spinal cord
• 2)Interneuron, located in brain or spinal cord
• 3)Motor neuron that cause the appropriate muscle
  to contract
• Inhibitory neuron from the brain may prevent
  this action(circuits) e.g. hot casserole

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• Neuro- modulator (action at a distance)
• Neurotransmitter travels a very short distance,
  and affect receptor molecule located on a small
  patch of the post synaptic membrane
• But, some neurons release chemical that get
  into the general circulation of the brain and
  stimulate receptors on many thousands of neurons,
  some located a considerable distance away, They
  are called neuromodulator e.g. opioid

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• Techniques in psychobiology
• Until recently, our knowledge of the functions of
  CNS was obtained through research using
  laboratory animals/
• 1- Lesioning
• The eldest and the common method,correlatinga
  behavioral deficit with a specific damage either
  present or produced

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• 2) Non-invasive recording of electric activity
• a-E.E.G., The activity is seen in the form of
  line-tracing, Some modern machines converts the
  EEG data into brain map i.e. colors
• Alert High frequency, low amplitude(12hz)
• RelaxAlpha(8-12),Theta(4-8),Delta(gt4HZ)

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• Event Related Potential (ERP)
• Evoked Potential(EP)
• To detect the activity produced by the perception
  of external stimulus or the response to internal
  stimulus (decision making), We have the average
  of EP
• N100 P300
• Nnegative Ppositive
• It appears after100 or300 millisecond of the
  onset of a stimulus

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• 3)Neuroimaging techniques
• - C T computerized Tomography (Tomos means cut)
• Narrow beam x rays through a person's head
  computer calculates the amount of radiation that
  passes through it at various point
• -PET (Positron Emission Tomography)
• It measures the brain metabolism, glucose
  consumption( radioactive glucose)
• It measures brain activity by examining the
  amount of glucose consumed.
• The radioactive part of glucose emit positrons
  positron emission which are detected by a PET
  scanner

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• MRI (Magnetic Resonance Imaging)
• More details than CT
• Magnetic field is passed over the head
• Reverberation are produced by hydrogen molecule
  and picked up by a scanner
• fMRIusing fMRI to measure the state of being in
  love
• -Activity was significantly high in the insula (a
  part of the brain involved in the visual
  interpretation of emotional information) and in
  the caudate nucleus and putamen nucleus
• -Deactivation was seen in the right prefrontal
  parietal and middle temporal cortices.

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• Control of internal functions and automatic
  behavior
• Beside CC there are other structure
• -the interior of cerebral hemisphere
• -cerebellum
• -brain stem
• They are important in the regulation of behavior.
• Cerebellum helps CH to control movement and to
  initiate some automatic movements such as
  postural adjustment.

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• Interior of CH and brain stem are involved in
• I Homeostasis Homeosimilar
• stasisstandstill
  (maintain a
• a proper balance of
  physiological variable)
• II Species-typical behavior automatic behavior
  exhibit by most members of species that are
  important to survival such as eating, drinking,
  fighting, courting, mating and caring for
  offspring.

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• Brain stem contains 3 structures
• I Medulla contains circuits of neuron that
  control heart rate, blood pressure and
  respiration rate and crawling or swimming motion
  esp. in simpler animals.
• II Pons circuits of neurons control sleep
  stages.
• III Midbrain control movements used in fighting
  and sexual behavior and decrease sensitivity to
  pain while engaged in these activities.

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• Endocrine gland endowithin
• Krinein to secrete
• -it produces hormones
• -it is similar to transmitter substance or
  neurotransmitter except that they act over much
  larger distance
• -it produces its effect by stimulating receptors
  molecules which are located on (or in) particular
  cells
• -it causes physiological reactions in these cells
  (target cells)
• (Almost every cell of the body contain hormone
  receptor if one kind or another)
• e.g. 6 hormones have an effect upon many neurons

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• Pituitary gland is the master gland, because it
  controls the activity of other endocrine glands
• -Thyroid control metabolism
• -Parathyroid control of mineral balance
• -Pancreas control carbohydrate metabolism
• -Adrenal Medulla (adrenaline and
  noradrenalin)_Breakdown of energy store
• _Blood pressure
• -Adrenal cortex (cortical steroid h) stress h.
• -Ovaries estrogen control menstruation,
  progesterone control pregnancy.
• -Testosterone control sperm production

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• Hypothalamus also control automatic nervous
  system, the homeostatic function can be involved
  in either internal physiological changes or
  behavior through CC. Stimulation of hypothalamus
  lead to rage, fear and avoidance reaction

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• Neural basis of instinctual behavior and emotions
  (The limbic system)
• -It has a role in olfaction
• -Along with hypothalamus it is concerned with
  autonomic responses
• -It is also concerned with sexual behavior
• -and concerned with the emotions of
• Rage-? fighting and attack behavior
• Fear? and avoiding reaction
• Motivation
• It was termed Rhinencephalon (smell brain)
• Were thought to be involved primarily in the
  sense of smell
• -Around the edge of CH where they join with the
  brainstem
• (LIMBUS MEAN BORDER)

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• Important parts are
• - Amygdale
• -Hippocampus
• Amygdala emotional behavior esp. negative
  emotions and it helps in providing energy for
  short term if prolonged ? stress related illness
• In animals without the amygdada it can not
  survive in the wild. It can not compete for food.
  It is considered with the encoding of memories
  that evoke fear snake and monkey
• In humans anxiety is associated with a bilateral
  increase in blood flow to discrete portion of the
  anterior end of each temporal lope.

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• Hippocampus plays an important role in memory
  and it is also responsible for the animal
  reaction to the environment esp. the novel
  stimuli.
• Rage placidity
• Normally there is a balance between Rage and
  placidity
• Destruction of hypothalamus ?Rage
• Destruction of Amygdala ?Placidity

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• Brain chemistry
• Aminergic systems
• Serotonin, Noradrenalin, Adrenaline, histamine,
  and Dopamine

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• Serotonin
• Serotonin containing neurons have their cell
  bodies with the midline raphe nuclei of the brain
  stem and project to
• -hypothalamus
• -limbic system
• -neocortex
• -spinal cord

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• -LSD is serotonin agonist, first ecstasy,
• then depression and insomnia
• -plays role in sleep
• In animals, if we give a drug that prevents
  manufacture of serotonin, it leads to prolonged
  wakefulness, but in human being no effect
• -prolactin secretion
• -pain pathways
• -circadian rhythm
• -plays a role in migraine
• -depression??
• -aggressive behavior

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• Norepinephrine
• The cell body contain norepinephrine is located
  in locus ceruleus in the pons and medulla,
  descend to spinal cord and cerebellum, ascend to
  thalamus, hypothalamus, striatum and neocortex
• Drugs that increase extra cellular norepinephrine
  ?elevate mood
• Drugs that decrease extra cellular norepinephrine
  ?depression
• The function remains a mystery, may regulate food
  intake and body temperature.

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• Epinephrin
• cell body located in medulla projected to
  hypothalamus and thalamus and spinal cord, no
  function has been assigned to this agent

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• Dopamine
• -ultra short in retina, in olfactory bulb
• -intermediate length
• Tuberinfundibular system prolactin
• -long length -negrostriatal ? involved in motor
  control
• -mesocortical from midbrain
  to limbic cortex and accumbens nucleus
• Amphetamines which increase dopamine activity may
  lead to some schizophrenic symptoms

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• Histamine
• In the hypothalamus project to all parts of
  brain, its role is unknown.
• Suggested role in arousal, sexual behavior,
  blood pressure, drinking, pain threshold and
  regulation of the secretion of the pituitary
  gland

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• Acetylcholine
• Distributed throughout CNS with high
  concentration in the CC thalamus and basal
  ganglia
• Involved in
• -memory, motivation, perception and cognition
• -Olfaction
• -It has a relation with Alzheimer and nicotine
• -in basal ganglia Acetylcholine is an excitatory
  transmitter while dopamine is an inhibitory
  transmitter
• -Acetylcholine may have a role in parkinsonism
• -Acetylcholine may have a role in REM sleep

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• Other transmitters
• Opioid, GABA (Chlorine conductance)
• Excitatory amino acids __ Glutamate
• __ Aspartate