Memory Gateway to Learning

Introduction What is memory? Positive and Negative Memory What is learning? Importance:Reward and punishment Role of hippocampus Survival Areas for storage: spinal cord reflexes Higher centers

Neural basis of memory Strength of synapse Consolidation Condification

Stages of memory Encoding-information for each memory is assembled from the different sensory systems and translated into whatever form necessary to be remembered. This is presumably the domain of the association cortices . Consolidation- Storage- Retrieval-

There is more than we can tell… How many stripes did you see on the cat?

Mechanism of presynaptic facilitation underlying behavioral sensitization Serotonin is released by modulatory interneuron and binds to GPCR neuro4e-fig-08-05-1r.jpg

Classification Short term (working memory) Intermediate term Long term

Mechanism of long-term synaptic enhancement neuro4e-fig-08-05-2r.jpg

Number of Neurons and Their Connectivities Often Change Significantly During Learning Learning” is achieved in adult human beings and animals by modification of numbers of neurons in the memory circuits Use it or lose it!

Many Structures are Involved in Memory

Implicit memory Procedural memory Priming skills and habits, which, once acquired, become unconscious and automatic. Priming is facilitation of recognition of words or objects by prior exposure to them. An example is improved recall of a word when presented with the first few letters of it.

Implicit memory In nonassociative learning, In associative learning, the organism learns about a single stimulus. In associative learning, the organism learns about the relation of one stimulus to another.

Working Memory Attention Working or Sensory Short-term Memory Input Key words: modal model of the mind; stage model of memory; sensory memory; attention; working memory; short-term memory

Hippocampus Maintenance Rehearsal Encoding Attention Working or Long-term memory Working or Short-term Memory Sensory Input Attention Encoding Retrieval Maintenance Rehearsal Key words: modal model of the mind; stage model of memory; sensory memory; short-term memory; working memory; long-term memory; attention; encoding; maintenance rehearsal; retrieval Note: The Hockenbury text refers to this as the stage model of memory

Implicit Memory Does not require conscious awareness

Amnesia - Loss of Memory Retrograde amnesia loss of memory for the time period before a trauma typically is gradational from essentially complete loss just before trauma to less and less complete loss earlier and earlier before trauma Anterograde amnesia inability to form new memories

Causes of Amnesia Causes Transient amnesia concussion, chronic alcoholism, encephalitis, brain tumor, stroke Transient amnesia Probably caused by interruptions in cerebral blood flow Blows to head, physical stress, drugs

Bilateral removal of the hippocampus Studied patients with surgical interventions to treat epilepsy Bilateral removal of the hippocampus and neighboring regions of the temporal lobe Most famous case was “H.M.”

The Diencephalon Three regions have been implicated in memory processing: Anterior nucleus of thalamus Dorsomedial nucleus of thalamus Mammillary bodies in hypothalamus The thalamus & mammillary bodies receive nerve fibers from the medial temporal lobe

Effects of lesion Lesion in dorsomedial thalamus: Cognitive ability normal but memory impaired Caused moderate retrograde amnesia and profound anterograde amnesia Short term memory and preservation of old memories was intact. Suggests that both the temporal lobe and parts of the thalamus may be involved in the formation of long-term declarative memories.

Neocortex and Working Memory Humans have much more prefrontal cortex than any other animals Pathways: Medial temporal lobe >> hypothalamus >> anterior nucleus of thalamus >> cingulate cortex Medial temporal lobe >> dorsomedial nucleus of thalamus >> frontal cortex Experiments suggest that frontal cortex is involved with working memory for problem solving and planning of behavior