Every think should be made as simple as possible, but not simpler
Study the role of physiology in the regulation and execution of behavior
-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
-Nerve cells differ as regards
*Kind of chemical they produced
-Nerve cells are organized in clusters that communicate with each other and connected to other circuits
Central Nervous System (CNS)
Peripheral nervous system(PNS)
The nerves which are attached to the spinal cord and the base of the brain
CNS is encased in the skull&vertebrae
Enclosed by a three membranes called meninges ( pleural of meninx )
They float in a fluid called Cerebro Spinal Fluid ( C S F )
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 )
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 (
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.
Peripheral nervous system PNS
Connect CNS with: sense organs
-some are attached to the spinal cord.
-others are attached directly to the brain (cranial nerve)
Other cells (Glial cells) (G glue)
-Brain’s immune system
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”
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.
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
Action potential (firing)
-It is not like electricity travel through a wire
-axon transmits information at a rate less than 100 meters /second
- Opening of Na channel to go in, after a brief time opening of Na channel to go out (rest position)
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
Excitation & Inhibition
-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
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.
Simple neuron circuit:
The interconnections of neurons provide us with the capacities for:
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
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
Techniques in psychobiology
Until recently, our knowledge of the functions of CNS was obtained through research using laboratory animals/
The eldest and the common method,correlatinga behavioral deficit with a specific damage either present or produced
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)
Event Related Potential (ERP)
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
It appears after100 or300 millisecond of the onset of a stimulus
- 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
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
fMRI:using 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.
Control of internal functions and automatic behavior
Beside CC there are other structure:
-the interior of cerebral hemisphere
They are important in the regulation of behavior.
Cerebellum helps CH to control movement and to initiate some automatic movements such as postural adjustment.
Interior of CH and brain stem are involved in:
I Homeostasis: Homeo=similar
stasis=standstill (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.
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.
Endocrine gland: endo=within
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
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
-Adrenal cortex: (cortical steroid h) stress h.
-Ovaries: estrogen control menstruation, progesterone control pregnancy.
-Testosterone: control sperm production
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
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
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)
Important parts are:
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.
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
Serotonin, Noradrenalin, Adrenaline, histamine, and Dopamine
Serotonin containing neurons have their cell bodies with the midline raphe nuclei of the brain stem and project to
-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
-plays a role in migraine
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.
cell body located in medulla projected to hypothalamus and thalamus and spinal cord, no function has been assigned to this agent
- 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
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
Distributed throughout CNS with high concentration in the CC thalamus and basal ganglia
-memory, motivation, perception and cognition
-It has a relation with Alzheimer and nicotine
-in basal ganglia Acetylcholine is an excitatory transmitter while dopamine is an inhibitory transmitter