1. Higher Functions Of The Brain
Physiology Unit

2. The objective of the lecture is to define types of memory and describe mechanism of learning and memory; and the role of the hippocampus in learning and memory.

3. Define learning and memory;
Differentiate the implicit and explicit memory; short-term and long-term memory
Explain the mechanisms of learning (habituation, sensitisation, learning by conditioning, learning by association)
Describe the intercortical transfer of memory and the storage of memory
Describe the basic mechanism of formation of long term memories
(consolidation) long-term potentiation.
Describe the role of the hippocampus in learning and memory.

4. WHAT ARE HIGHER FUNCTIONS?
SPEECH
LEARNING AND MEMORY
INTELLECTUAL FUNCTIONS
IMAGINATION AND OTHER FUNCTIONS OF MIND

5. Non-associative learning
Habituation : “Learn to ignore the not so important information”
HABITUATION X SENSITISATION
Non-associative learning

6. CNS Consists of brain and spinal cord
Receives input from sensory neurons
Directs activity of motor neurons
Association neurons integrate sensory and motor activity
Perform learning and memory
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7. Primary & Secondary Sensory & Motor & Association Cortical Areas

8. Primary & Secondary Sensory & Motor & Association Cortical Areas
Primary Sensory area- detect specific sensations e.g. somatic, vision, hearing-
Primary Motor area- causes discrete muscle movements---
Secondary areas make sense out of the signals received by the primary areas
Association Areas- Concerned with higher level of interpretive function.

9. Association Areas
Frontal association area( volitional association area)
Temporal association area
Somatic sensory association area
Visual association area
Auditory association area
Wernicke’s area
Association areas very important for the higher functions

10. Language Broca’s area is necessary for speech
Wernicke’s area is involved in language comprehension
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11. Memory Includes short- and long-term memory
Involves a number of regions in brain
There are two types of long-term memory
Non-declarative (explicit) includes memories of simple skills and conditioning
Declarative (implicit) includes verbal memories
Amnesiacs have impaired declarative memory
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12. Memory continued Hippocampus is critical for acquiring new memories
And consolidating short- into long-term memory
Amygdala is crucial for fear memories
Storage of memory is in cerebral hemispheres
Higher order processing and planning occur in prefrontal cortex
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13. Long-Term Potentiation (LTP)
Is the increased excitability of a synapse after high frequency stimulation
Glutamate activates AMPA and NMDA postsynaptic receptors in hippocampus
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14. Neurogenesis in Hippocampus
Appears to be crucial for learning and memory
Hippocampus contains neural stem cells that continually produce new neurons (neurogenesis)
Stress or depression impede learning and cause hippocampus to shrink
Stress reduction and antidepressants return size to normal
8-40

15. Sensory association areas (secondary sensory areas) extend 1-5 cm from the primary sensory areas
Sensory association areas are concerned with the interpretation of the sensory experiences.
A lesion of primary visual cortex causes blindness
A patient with a lesion of visual association area can see the object but cannot interpret what he sees.

17. Wernicke’s Area
Located in the posterior part of the superior temporal lobe, highly developed in dominant side of the brain
A general interpretive area concerned with intelligence / higher level of comprehension

18. Language & Speech

19. Language & Speech ( Cont. )
Main area for interpretation of language is: Wernicke’s Area Which gets input from hearing areas of the temporal lobe and from visual association area

20. Thoughts / Thinking Holistic theory :
A thought results from a patternof stimulation of many parts of the Nervous system mainly Cerebral Cortex, Thalamus, Limbic System, Brain stem Upper Reticular formation.

21. LEARNING & MEMORY Learning: Acquisition of information, Skills Memory:
Retention & storage of information

22. Types of Memory Explicit / Declarative
(Memory of an integrated thought---)
Associated with:
Consciousness
Involves:
Hippocampus,
Medial temporal lobes of brain—
e.g. words, language, an experience--
Implicit / Non-declarative / Reflexive
Skill Memory
Does not involve hippocampus---
Includes- Skills, Habits, Reflexes, ---

23. Memory Classification ( Cont. )
Common Classification of Memory:
Short term- Lasts Secs to mins, Subject to disruption by trauma & drugs etc
Intermediate- last for days to wks
Long term- Stored for years to life time.

24. Learning & Memory- Mechanisms
Neural Substrate:
A number of neural pathways from periphery to centre (prefrontal cortex) are involved in any learning & memorizing process.
For short term Learning & Memory the relevant sensory – motor nerve terminals & synapses get activated—
For long term- Activation of genes produce increased synaptic contacts.

25. Memory ( Cont. ) Consolidation of Memory:
Short term memory if activated repeatedly initiate changes in synapses leading to long term memory---
Varies from minimum to strong consolidation
(Rehearsals enhance trnsference of short term to long term memory--)

26. Wernicke’s Area
Located at the posterior end of superior temporal gyrus.
Site of integration of somatic, auditory and visual association areas
In the left hemisphere, it acts as a tertiary association area.
It integrates information from visual and auditory and somatic association areas and formulates ideas for expressive part of speech.
Connected to area 44 of the left hemisphere----the motor speech area (spoken and written)

27. Language A well developed higher function of the cerebral cortex
It is an ability to understand or express oneself by spoken or written words.
Predominantly controlled by left cerebral hemisphere in most of the individuals who are also right-handed.
Hence left hemisphere some times known as the dominant hemisphere

28. Language ---two components
Receptive component (sensory speech areas) consist of
Visual association area for written speech
Auditory association area for spoken speech

29. Expressive components (motor speech areas)
Area 44 for spoken speech
An area close to area 44 for written speech
Integrated by Wernicke’s area
All the speech centers situated in the left hemisphere in most of the individuals

30. Higher functions of Left hemisph. Right hemisph.
Right hand control Left hand control
Spoken language Music awareness
Written language Three dimensional
awareness
Mathematical skills Art awareness
Scientific skills Insight
Reasoning Imagination

31. LEARNING
Learning is a function of the entire cerebral cortex in human.
When new sensory stimulus is applied, the human or animal becomes alert and attentive.
This response is called the “orienting reflex” ” by pavlov.
This sort of response is essential for learning, without which learning becomes difficult. 31

32. Learning and Memory Closely related
Learning is the ability to alter behavior on the basis of past experiences.
Memory is the ability to recall the past experiences at conscious or unconscious levels

33. Learning Associative learning----- the conditioned reflexes
Non-associative learning---learned skills and habits
Learning encoded in the basal ganglia/cerebellum

34. Declarative memory Conscious recall of facts or events
Stored in two steps
Primary memory or recent memory
Secondary memory or long term memory
Primary memory due to entrance of sensory signals in reverberating circuits. Soon wiped out unless the effect is strong
Secondary memory due to almost permanent anatomical or biochemical changes in cerebral synapses
Long term memories are encoded by hippocampus and stored in the neocortex

35. Experiment of Sham feeding by Pavlov35

36. The Hippocampus
It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is a part of the cerebral cortex.

37. The Hippocampus………..
Anatomically, the hippocampus is an elaboration of the edge of the cerebral cortex.
The structures that line the edge of the cortex make up the so-called limbic System (Latin limbus = border): these include the hippocampus, cingulate cortex, olfactory cortex, and amygdala.

38. The Hippocampus Function
The dorsal region of the hippocampal formation serves for spatial memory, verbal memory, and learning of conceptual information. The ventral hippocampus functions in fear conditioning and affective processes.

39. Complementary specialisation of
cerebral hemispheres:
Right and left hemispheres
“It is experimentally concluded that the left hemisphere of the brain is dedicated to language. On the other hand the right hemisphere of the brain is involved in more creative activities such as drawing.”

41. Thank You