REVIEW OF STRUCTURE AND FUNCTION OF BRAIN, LIMBIC SYSTEM, ABNORMAL NEUROTRANSMISSION

1. WELCOM
E
JINTO PHILIP
ASST. PROFESSOR
MSc in Psychiatric Nursing

2. REVIEW OF STRUCTURE AND FUNCTION OF
BRAIN, LIMBIC SYSTEM, ABNORMAL
NEUROTRANSMISSION
COMPONENTS OF THE NERVOUS SYSTEM
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Psychobiology: Study of biological foundations
of cognitive, emotional and behavioral
processes.

3. CENTRAL NERVOUS SYSTEM
A. Brain
B. Nerve tissue
C.Spinal cord
Forebrain
Hindbrain
Neurons
Synapses
Neurotransmitters
Fiber tracts
Spinal nerves
Midbrain

4. PERIPHERAL NERVOUS SYSTEM
A. Afferent system
Sensory neurons
B. Efferent system
Somatic Nervous System-somatic motor neurons
Autonomic Nervous System
Somatic
Visceral
Sympathetic nervous
System
(Visceral motor neurons)
Parasympathetic nervous
system
(visceral motor neurons)

5. THE BRAIN
Forebrain
Hindbrain
Midbrain
-Mesencephalon
Occipital lobe
Cerebellum
Medulla
Cerebrum
Diencephalon
Pons
Temporal lobe
Parietal lobe
Frontal lobe
Thalamus
Hypothalamus
Limbic system

6. Frontal lobe
Motor area
Premotor area
Visual
association area
Occipital lobe
Parietal lobe
Sensory association area
General sensory area
Visual area
cerebellumMotor speech
area
Auditory association
area
Temporal lobe
Auditory area
The human brain: cerebral lobes, cerebellum and brainstem

7. The human brain: midsagittal surface
Thalamus
Corpus callosum
Frontal lobe
Parietal lobe
Pons
Medulla
Spinal cord
Cerebellum
Midbrain
Occipital lobe
Hypothalamus
Pituitary gland
Temporal lobe

8. 1. CEREBRUM:
- Two hemispheres separated by the corpus callosum.
- The outer shell is called the cortex.
- The left hemisphere appears to be dominant in most
people. It controls speech, comprehension, rationality, and
logic.
- The right hemisphere is nondominant in most people.
Sometimes called the “creative” brain, the right hemisphere is
associated with affect, behavior, and spatial perceptual
functions.
- Each hemisphere is divided into four lobes

9. Frontal lobes:
-Controls voluntary body movement, including
movements that permit speaking, thinking, and
judgment formation.
-Also play a role in the emotional experience, as
evidenced by changes in mood and character after
damage to this area (fear, aggressiveness, depression,
rage, euphoria, irritability, and apathy).

10. Parietal lobes:
-The parietal lobes control perception and
interpretation of most sensory information (including
touch, pain, taste, and body position).
-Language interpretation is associated with the left
hemisphere of the parietal lobe.

11. Temporal lobes:
-The upper anterior temporal lobe is concerned with auditory
functions, while the lower part is dedicated to short-term
memory.
-impulses carried by the olfactory nerves end in this area of
the brain.
-play a role in the expression of emotions through an
interconnection with the limbic system.
-The left temporal lobe, along with the left parietal lobe, is
involved in language interpretation.

12. Occipital lobes:
-Primary area of visual reception and interpretation.
Visual perception, which gives individuals the ability to
judge spatial relationships such as distance and to see in
three dimensions, is also processed in this area.
-Language interpretation is influenced by the occipital
lobes through an association with the visual experience.

13. 2. DIENCEPHALON:
The diencephalon connects the cerebrum with lower brain
structures. Its major structures include the thalamus,
hypothalamus, and limbic system.
● Thalamus:
-Integrates all sensory input (except smell) on its way
to the cortex.
-some involvement with emotions and mood.
• Hypothalamus:
-Regulates the anterior and posterior lobes of the
pituitary gland.
-exerts control over the actions of the autonomic
nervous system, and regulates appetite and temperature.

14. ● Limbic system:
The limbic system consists of medially placed
cortical and subcortical structures and the fiber tracts
connecting them with one another and with the
hypothalamus. These structures include the
hippocampus, mammillary body, amygdala, olfactory
tract, hypothalamus, cingulate gyrus, septum
pellucidum, thalamus, and fornix. The limbic system,
which is sometimes called the “emotional brain,” is
associated with fear and anxiety; anger and aggression;
love, joy, and hope; and sexuality and social behavior.

15. Cingulate gyrus
Septum pellucidum
Thalamus
Hypothalamus
Olfactory tract
Amygdala
Mammillary body
Fornix
Hippocampus
Structures of the limbic system

16. MIDBRAIN
MESENCEPHALON:
-Structures of major importance in the mesencephalon, or
midbrain, include nuclei and fiber tracts.
-Extend from the pons to the hypothalamus and are
responsible for the integration of various reflexes.
Visual reflexes (e.g., automatically turning away from a
dangerous object when it comes into view),
Auditory reflexes (e.g., automatically turning toward a sound
that is heard),
Righting reflexes (e.g., automatically keeping the head upright
and maintaining balance).

17. HINDBRAIN
Its major structures include pons, medulla and cerebellum.
PONS: The pons is the bulbous structure that lies between
the midbrain and the medulla
-composed of large bundles of fibers
-forms a major connection between the cerebellum and the
brainstem.
-Regulation of respiration and skeletal muscle tone.

18. MEDULLA:
-Provides a pathway for all ascending and descending
fiber tracts.
-Contains vital centers that regulate heart rate, blood
pressure, and respiration, and reflex centers for swallowing,
sneezing, coughing, and vomiting.
The medulla, pons, and midbrain form the structure
known as the brainstem.

19. CEREBELLUM:
-Separated from the brainstem by the fourth ventricle, but
it has connections to the brainstem through bundles of
fiber tracts.
-It is situated just below the occipital lobes of the
cerebrum.
-The functions of the cerebellum are concerned with
involuntary movement, such as muscular tone and
coordination and the maintenance of posture and
equilibrium.

20. NEURONS:
-Generate and transmit electrochemical impulses.
-Structure  a cell body, an axon, and dendrites.
-Cell body contains the nucleus
-The dendrites are processes that transmit impulses toward
the cell body, and the axon transmits impulses away from
the cell body.
-Cells called afferent (or sensory) neurons carry impulses
from the periphery to the CNS, where they are interpreted
into various sensations.
-The efferent (or motor) neurons carry impulses from the
CNS to the muscles and glands of the periphery.

21. SYNAPSES:
The junction between two neurons is called a synapse.
The small space between the axon terminals of one
neuron and the cell body or dendrites of another is called the
synaptic cleft.
Neurons conducting impulses toward the synapse are
called presynaptic neurons and those conducting impulses
away are called postsynaptic neurons.

22. NEUROTRANSMITTERS
-Chemicals called neurotransmitters are stored in the
axon terminals of presynaptic neurons.
-Electrical impulses cause the release of these chemicals
into the synaptic cleft.
-The neurotransmitter combines with receptor sites on the
postsynaptic neuron, resulting in a determination of whether
another electrical impulse is generated.

23. -Neurotransmitters are responsible for essential
functions in the role of human emotion and behavior.
-Target for the mechanism of action of many of the
psychotropic medications.
After a neurotransmitter has performed its function in
the synaptic cleft, it either returns to the vesicles in the
axon terminals to be stored and used again (reuptake), or
it is inactivated and dissolved by enzymes.

24. Impulse transmission at a synapse
Axon of
presynaptic neuron
Dendrite of
postsynaptic
neuron
Vesicles of
neurotransmitter
Receptor site
Inactivator
(cholinesterase)
Inactivated
neurotransmitterNeurotransmitter
(acetylcholine)
Mitochondria

25. CHOLINERGICS
ACETYLCHOLINE: Acetylcholine was the first chemical to
be identified and proven as a neurotransmitter.
● Location: ANSsympathetic and parasympathetic
presynaptic nerve terminals, parasympathetic
postsynaptic nerve terminals.
CNScerebral cortex, hippocampus, limbic
structures, and basal ganglia.
● Functions: Acetylcholine is implicated in sleep, arousal,
pain perception, the modulation and coordination of
movement, and memory acquisition and retention.
● Possible implications for mental illness:
Increased levels- Depression
Decreased level- Alzheimer’s disease, Huntington’s disease,
Parkinson’s disease

26. MONOAMINES
NOREPINEPHRINE:
● Location: ANS sympathetic postsynaptic nerve
terminals.
CNS cerebral cortex, hippocampus, limbic
structures, thalamus, hypothalamus and cerebellum
● Functions: Mood, cognition, perception, locomotion,
cardiovascular functioning, sleep and arousal.
● Possible implications for mental illness:
Decreased levels- Depression
Increased level- Mania, anxiety states, schizophrenia

27. MONOAMINES
Dopamine:
● Location: ANS frontal cortex, limbic structures,
basal ganglia, thalamus, posterior pituitary, and spinal
cord.
● Functions: Movement and coordination, emotions,
voluntary judgment, release of prolactin.
● Possible implications for mental illness:
Decreased levels- Parkinson’s disease and Depression
Increased level- Mania and schizophrenia

28. MONOAMINES
Serotonin:
● Location: ANS hypothalamus, thalamus, limbic
system, cerebral cortex, cerebellum, spinal cord.
● Functions: sleep and arousal, libido, appetite,
mood, aggression, pain perception, coordination,
judgment.
● Possible implications for mental illness:
Decreased levels- Depression
Increased level- Anxiety states

29. GAMMA-AMINOBUTYRIC ACID (GABA): Inhibitory
amino acid
● Location: hypothalamus, hippocampus, cortex,
cerebellum, and basal ganglia of the brain; spinal cord; and
in the retina.
● Functions: GABA interrupts the progression of the
electrical impulse at the synaptic junction, producing a
significant slowdown of body activity.
● Possible implications for mental illness:
Decreased levels: anxiety disorders, movement disorders
such as Huntington’s disease, and various forms of
epilepsy.

30. ABNORMAL NEUROTRANSMISSION
Deficient neurotransmitter
Excess neurotransmitter
Deficient receptors
Excess receptors
Abnormal neurotransmission causes some mental
disorders because of excess/deficient transmission or
excess/deficient responsiveness of receptors.

31. NEUROENDOCRINOLOGY
-Pituitary gland- under direction of hypothalamus.
-Master gland
-Two major lobes
Anterior lobe (adenohypophysis) –Growth
hormone, Thyroid stimulating hormone,
Adrenocorticotropic hormone, prolactin, Gonadotropic
hormone, Melanocyte stimulating hormone.
Posterior lobe (neurohypophysis)- Antidiuretic
hormone, Oxytocin