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					High cortical
 functions
           By
 Dr. Dalia Abd-Elhalim
  Map of specific functional areas in the cerebral
cortex, showing especially Wernicke’s and Broca’s
  areas for language comprehension and speech
 production, which in 95 per cent of all people are
           located in the left hemisphere
Function of the brain in communication
Language input and Language output
There are two aspects to communication:
1- The sensory aspect (language input),
involving the ears and eyes
2- The motor aspect (language output),
involving vocalization and its control.
       Sensory aspect of speech
1- Hearing and speech
Hearing of spoken words is the function of
primary auditory area
Understanding the meaning of the individual
words is the function of auditory association area
2- Reading and speech
Seeing the written words is the function of
the primary visual area
Understanding the meaning of the individual
written words is the function of visual
association area
 Sensory aspect of speech (cont.)
 Both auditory and visual association
areas feed the meaning of words to the
Wernicke’s area
This area is involved with language
comprehension and is important for
understanding spoken and written
messages
      Motor aspect of speech
1- Broca’s area (Word formation area)
Impulses are transmitted from Wernicke’s
area to Broca’s area, which stimulate the
motor areas of the cortex that control the
muscles necessary for articulation.
Brain pathways for perceiving a heard
word and then speaking the same word
Brain pathways for perceiving a written
word and then speaking the same word
      Motor aspect of speech
2- Writing center (Exner’s center)
-It is part of the area of hand skills in
premotor cortex. It is connected to the
Wernicke’s area
-It stores the program for writing the words
-It stimulate the motor cortex to write word
using the muscles of the hand
         Speech disorders
1- Aphasia:
A speech defect which is not due to defect in
vision, hearing or paralysis of speech
muscle.
2- Dysarthria
A speech defect due to defect in the process
of articulation
               Aphasia
1- Sensory aphasia (receptive aphasia)
a. Auditory aphasia (word deafness)
b. Visual aphasia (word blindness)
c. Wernicke’s aphasia
2- Motor aphasia (expressive aphasia)
a. It results from damage to Broca’s area
b. Writing aphasia (agraphia)
3- Global Aphasia
    Learning and memory
Learning and memory are higher-level
functions of the nervous system.
Learning is the neural mechanism by which
a person changes his or her behavior as a
result of experiences.
                   Memory
This the ability of the brain to store and recall
information.
It is a function of the synapses
Memories are classified according to the type of information
that is stored into:
1- Declarative memory (The hippocampus, amygdala, and
diencephalon—all parts of the limbic system—are required
for the formation of declarative memories
2- Nondeclarative memory (skill memory): regions of
sensorimotor cortex, the basal ganglia, and the cerebellum
        Memory (cont.)
Classification of declarative memory:
1- short-term memory, which lasts for seconds or
minutes unless they are converted into longer-term
memories.
2- intermediate long-term memories, which last for
days to weeks but then fade away.
3- long-term memory, which, once stored, can be
recalled up to years or even a lifetime later.
 Short-term memory is typified by one’s memory
of 7 to 10 numerals in a telephone number. It
caused by continual neural activity in a circuit of
reverberating neurons. Another explanation is
presynaptic facilitation or inhibition.
 The intermediate long-term memory results
from temporary chemical or physical changes, or
both, in either the presynaptic terminals or the
postsynaptic membrane, changes that can persist
for a few minutes up to several weeks.
The intermediate long-term memory (cont.)
A positive memory results from facilitation of the
Synaptic pathways, and the process is called
memory sensitization.
A negative memory results from inhibition of the
synaptic pathways, the resulting effect is called
habituation.
 Long-Term Memory results from actual
structural changes at the synapses
The structural changes are the following:
1. Increase in vesicle release sites for secretion of
neurotransmitter.
2. Increase in number of transmitter vesicles.
3. Increase in number of presynaptic terminals.
4. Changes in structures of the dendritic spines
   that permit transmission of stronger signals.
        Consolidation of memory
 It is the conversion of short term memory into
long term memory
 This process requires 5 to 10 minutes for
minimal consolidation and 1 hour or more for
strong consolidation.
 This is produced by rehearsal of the information
in the mind. It involves new protein synthesis in
neurons
          Encoding of memory
 One of the most important features of
consolidation is that new memories are codified
into different classes of information.
 Informations are first processed in the
hippocampus then is stored with other memories
of the same type
   Centers of memory encoding
           and storage
1- Nondeclarative memory: Basal ganglia and
cerebellum
2- Declarative memory:
short term memory is encoded in the hippocampus,
to be converted to long term memory  mamillary
bodies anterior hypothalamus prefrontal
cortex basal forbrain all parts of the neocortex,
the amygdaloid nuclei and the hippocampus.
  Centers of memory encoding
      and storage (cont.)
Long term memory are stored in the Neocortex


     Amnesia = loss of memory
Retrograde amnesia
Anterograde amnesia
Hysterical amnesia
Global amnesia
                   Learning
Learning is categorized as
1- Nonassociative learning:
a. habituation, a repeated stimulus causes a
response, but that response gradually diminishes
as it is "learned" that the stimulus is not important
b. sensitization, where a stimulus results in a
greater probability of a subsequent response when
it is learned that the stimulus is important
                Learning
2- Associative learning
This learning by pairing of stimuli. Example,
is learning through conditioned reflexes
Classic conditioning
operant conditioning
Synaptic plasticity is the fundamental
mechanism that underlies learning
Pavlov’s experiment
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The Limbic system

             BY
   Dr. Dalia Abd-Elhalim
          The Limbic System
It consists of:
1- The limbic lobe which contains the cingulate
  gyrus, the hippocampal gyrus as well as the
  uncus, the piriform and entorhinal cortex
2- Certain subcortical structures including the
  amygdaloid nuclei, hippocampus, hypothalamus,
  fornix, anterior thalamic nucleus, septal nuclei
  and upper part of the midbrain (limbic midbrain
  area, LMA)
Anatomy of the limbic system
Limbic system, showing the key
  position of the hypothalamus
  Functions of the limbic system
1- Reward and Punishment function
Reward centers are in the lateral and ventromedial nuclei
of hypothalamus
Stimulation of reward center  sense of reward (pleasure
and satisfaction)
Punishment centers:
a major center is the periventricular nucleus of
hypothalamus and its extension downward to the PAG
Less potent centers: Amygdala and hippocampus
Stimulation of punishment centers  Sense of punishment
(displeasure, fear and terror)
    Importance of Reward and
      Punishment sensations
1- In behavior
2- In Memory and learning
Technique for localizing reward and
 punishment centers in the brain of
            a monkey
 Functions of the limbic system (cont.)
2- function of limbic system in motivation
The main center for motivation is in the
limbic association area. Other parts of the
limbic system help the motivation
3- function of limbic system in behavior
a. Feeding behavior: the amygdaloid
nucleus is concerned with sorting out types
of food into edible and inedible
b. Sexual behavior
 Functions of the limbic system (cont.)

4- Function of limbic system in emotions
a. Rage strong stimulation of the punishment
Centers especially the periventricular zone of the
hypothalamus or the amygdala  rage reaction
Placidity  due to bilateral damage to amygdaloid
nuclei
b. Fear  stimulation of amygdaloid nuclei
5- Analysis of olfactory stimuli
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