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1. NEUROBIOLOGY OF MEMORY Moderator- Dr. Swati Arora (Associate Professor ) P resenter – Dr.Kanupriya Yadav (Junior Resident - 1) Department of Psychiatry NCRIMS, MEERUT

2. CONTENTS 1)INTRODUCTION 2)MODELS OF MEMORY 3)TYPES OF MEMORY 4)NEUROBIOLOGY OF MEMORY 5)PROCESS OF MEMORY FORMATION 6) THEORIES OF FORGETTING 7) REFERENCES

3. INTRODUCTION Memory is the glue that binds mental life, the scaffolding for personal history. Memory is a special case of the general biological phenomenon of neural plasticity . A major source of information about memory has come from extended study of the marine mollusk Aplysia californica (a sea slug) Aplysia is capable of associative learning (including classic conditioning and operant conditioning) and non-associative learning (habituation and sensitization)

4. MODELS OF MEMORY 1 Information-processing theories ( Atkinson & Shiffrin 1968) 2 Craik and Lockhart level processing model 3 Working memory model 1 THEORIES OF MEMORY PROCESSING/MULTIMODAL THEORY The Information Processing or the Multi-store model was proposed by Richard Atkinson & Richard Shiffrin (1968). This model derives an analogy from a computer's operation and serves as the basis for the information-processing theory's model of the human mind ( Massaro & Cowan, 1993). This model indicates that information travels from one storage area to another (Sternberg, 2009).

5. INFORMATION PROCESSING MODEL ATKINSON AND SHIRIFFIN 1968 Stimuli Attention Duration: 0.2 to 2 seconds Maintenance & Elaborative Rehearsal Encode Retrieve Sensory Memory Duration: 15 to 20 seconds (without rehearsal) Duration: Permanent Working Memory Long-Term Memory Forgotten Forgotten

6. 2 CRAIK & LOCKHART LEVEL PROCESSING MODEL ( Craik and Lockhart, 1972) Shallow Processing- PERCEPTION- It’s the first level, which gives immediate awareness of the environment. STRUCTURAL- Tells, about physical features, what it looks like (shape, color , size) or sounds like. Deep Processing : MEANING- It’s the deepest level, when we encode the meaning of a word and relate it to similar words with similar meanings linking them with previous knowledge.

7. 3).WORKING MEMORY THEORY ( Badd e ley & Hitch 1974 (Upgraded in 1990) They considered working memory as an ACTIVE MEMORY ,with 3 components: 1 The central executive system 2 Phonological loop 3 Visuospatial sketchpad 1 . The central executive system : Acts as attentional controller with limited capacity, it controls the decision making. 2. Phonological stores: H olds memory traces of verbal information lasting upto 1.5-2 sec combined with subvocal rehearsal. 3. Visuospatial scratch pad : Allows temporary storage and manipulation of visual & spatial information .

8. TYPES OF MEMORY

9. SENSORY MEMORY Definition : The brief retention of sensory information , it’s the initial and early phase of memory. It’s a selecting and recording system via perceptions enter the memory system. Duration : Iconic(visual) lasts for - 200 ms , fleeting visual image. Auditory memory ( echoic ) lasts for- 2000ms ( 2sec ) Most sensory memory fades within a few seconds unless selectively attended or recognised. Purpose : Facilitate comparisons with stored material in short- and long-term memory & allows selective attention to specific stimuli. Example : when walking in a park, you briefly register multiple stimuli( trees, kids, playing, dog barking) Brain structures involved- visual, auditory, tactile and spatial systems.

10. SHORT TERM MEMORY/WORKING MEMORY Definition : Temporarily holds information for active or immediate use and processing and information is unstable and labile . Duration : 15-30 seconds without rehearsal. Key Processes : Rehearsal, Chunking. Purpose: Manipulation of information,enables task coordination-driving while talking, remembering facts like remembering phone number while dialing . Example : Linking the sound of a dog barking with the image of someone walking with a dog or calculating change during transaction. Clinical Relevance : Impaired in conditions like ADHD, schizophrenia, dementia, and Alzheimer’s disease . Brain structure involved- Prefrontal cortex

11. LONG TERM MEMORY Definition : Storage of information over extended periods. i.e ; from hours to lifetime Types- Declarative (Explicit): Facts and events. (hippocampus, frontal lobe & prefrontal cortex) Non-declarative (Implicit): Skills and habits (cerebellum, basal ganglia and amygdala) DECLARATIVE(EXPLICIT MEMORY ) Definition : Conscious recall of facts or events , requiring active efforts. Subtypes: 1-Episodic Memory / Autobiographical : Specific events ( eg , going to the shop). 2-Semantic Memory : Factual knowledge ,storage in pure form without specification of time or place. ( eg - capital of india , language learnt ). Neural Basis : Hippocampus: Encoding and consolidation. Prefrontal Cortex: Working memory and retrieval. Medial Temporal Lobe: Long-term storage.

12. NON-DECLARATIVE(IMPLICIT) MEMORY NON-DECLARATIVE(IMPLICIT MEMORY) : It refers to the influence of experience on behaviour , even if the individual is not aware of those influences. It is important as it has a direct effect on our behaviour and doesn’t requires active efforts to form or recall. 3 general types - ▪ Procedural memory : It r efers to our unexplainable knowledge of how to do things , involving skills & procedures eg -driving, cooking or ride a bicycle that are performed subconciously once learned. ▪ Classical Conditioning effect : It is learned association of a neutral stimuli (such as a sound / light), often without effort or awareness, with another stimulus (such as food), which creates a naturally occurring response, such as salivation. The memory for the association is demonstrated when the conditioned stimulus (the sound) begins to create the same response as the unconditioned stimulus (the food).

13. Priming : Priming refers to an improvement in processing /subsequent performance or understanding concepts when they have been presented frequently or recently having influence of prior exposure. Eg - showing word ‘’yellow’’ before list of fruits may lead quicker recognistion of ‘’banana’’.

14. NEUROBIOLOGY OF MEMORY Cellular and Molecular Basis - Long-Term Potentiation (LTP): Strengthening of synaptic connections after repeated stimulation. Particularly observed in hippocampus and amygdala of Temporal lobe (e.g., CA1 region). Neurotransmitters: Glutamate (especially through NMDA receptors) is critical for LTP. Acetylcholine important for attention and memory (reduced in Alzheimer’s). Dopamine and norepinephrine involved in emotional memory modulation.

15. LTP

16. LONG TERM POTENTIATION High-frequency stimulation of pre-synaptic neuron ↓ Glutamate released into synaptic cleft ↓ Activation of AMPA receptors →Initial depolarization & persists( Persistently Na + enter) ↓ NMDA receptors activated (after depolarization removes Mg²⁺ block) ↓ Influx of Ca²⁺ ions into postsynaptic neurons ↓ Activation of intracellular signaling pathways (Activation of kinases- PKC) ↓ Insertion of more AMPA receptors into postsynaptic membrane ↓ Strengthening of synapse (increased sensitivity to glutamate) ↓ Formation and consolidation of long-term memory

17. PROCESS OF MEMORY FORMATION Phenomenologically 5 functions known as 5 Rs:( OYEBODE 2008): A . Registration/Encoding : To add new information to memory storage. Several techniques can enhance encoding as follows- Imagery- Forming mental images of the information to be remembered. Constructive process- Selectively remembering the most important parts of information and to-be- remebered information is ‘Modified’ far different from original one. Structured organization- Organizing information into categories or hierarchy levels. Associating Retrieval clues- For later recall. SUBJECTIVE ORGANISATION- To make our own organisation and categorisation of incoming information by some of our own recalling patterns. B . Retention /Storage : To maintain the knowledge stored with returning to conscious level when needed .

18. ORGANIZATION IMAGERY C-Concrete , A-Abstract

19. There are 2 types of rehearsal- Maintenance Rehearsal- This involves simple passive process of repetition of information without deeper processing or meaning to it and useful for maintaining STM> LTM. Example : Repeating a phone number to yourself until you dial it, silently or aloud. Elaborative Rehearsal- Involves deeper processing of information by giving it meaning and organising , connecting it to existing knowledge and more effective for LTM. Techniques includes- 1) CHUNKING : Grouping information into meaningful units. Example- Phone numbers: Instead of 1234567890, we chunk it as 123-456-7890. 2) MNEMONIC : Creating associations or acronyms 3) VISUALIZATION :Creating mental images of the information 4) RELATING NEW INFO TO EXISTING KNOWLEDGE

20. C . Retrieval : Capacity to access stored information by recognition, recall or demonstrating that a relevant task is performed more efficiently as a result of prior experience. D . Recall : Effortful retrieval of stored information into consciousness actively . It involves primacy and recency effect. Eg - W hat is the capital of France? E . Recognition : Retrieval of stored information depending on the identification of previously learned things depending on remember(effortful/conscious) or knowing (familiarity based) & no active efforts required. Eg - Which of the following is capital of France- Paris, Lyon or Lille?

21. STATE-DEPENDENT MEMORY IN RETRIEVAL FROM LTM

22. With delay, Recency is decreased or eliminated but not Primacy.

23. THEORIES OF FORGETTING 1)Interference Theory – Retroactive interference - occurs when new memories interfere with the retrieval of old memories . Proactive interference - occurs when old memories interfere with the learning of new information . Interpretation : If Task B interferes with recall of Task A, it shows retroactive interference . If prior learning of Task A hinders learning/recall of Task B, it shows proactive interference .

24. 2.) Retrieval Problems - Poor encoding or storage processes can lead to difficulties in retrieval. Examples include unstructured organization, lack of cues, and improper construction of memories. These problems can lead to distortions or falsifications of memory during recall Like Confabulation

25. 3.) Motivated Forgetting- This involves the subconscious repression of traumatic or painful memories. It is related to defense mechanisms in psychoanalytic theory.

26. 26 Memory Impairment Amnesia-     Partial or complete L oss of ability to recall. Paramnesia - Distortions of Memory during recall/recognition. Hyperamnesia - Exaggerated registration, retention and re trieving .

27. REFERENCES 1)Kaplan & Sadock's Comprehensive Textbook of Psychiatry (11th ed.) 2)Fish's Clinical Psychopathology: Signs and Symptoms in Psychiatry (5 th ed.) 3) Introduction To Psychology Morgan And King ( 9th ed .) 2025 4 ) Femi Oyebode , Sims’ symptoms in the Mind. (7 th ed.)

28. THANK YOU