Memory

Encoding, Retrieval, and Recall

Types of Memory

(Explicit) (Implicit)

Context-Dependent Memory (based on experience)

Context-Dependent Memory(based on current state)

Emotional Memory

Motor Memory

Neural Control of Memory

The Hippocampus and Related Structures

Parahippocampal Cortex (Green)Entorhinal Cotrex (Blue)Dentate Gyrus (Purple)CA3 (Purple)CA1 (Purple)Subiculum

Principles of Neuroscience (4th Edition): Chapter 59

Neuronal Signaling Within Hippocampus Predicts Recall vs. Forgetting

Hippocampal Morphology as a Result of Experience

Amnesia

• Retrograde: can’t remember (recall) life before injury

• Anterograde: can’t remember (encode) life after injury– All types of memory affected although these two

distinctions largely refer to episodic memory

• Patient HM was the most rigorously studied amnesiac

Patient HM• In the summer of 1953, Henry Gustav Molaison (1926-2008) underwent brain surgery to

contain epileptic seizures that had become critically debilitating. The intervention brought some relief from convulsions, but these positive results were overshadowed by an astonishing and indelible side effect. Soon after the operation, it became apparent that he could no longer recognize hospital staff, he did not remember the way home, he did not remember newspaper articles he had just read, nor the crossword puzzles he had solved; otherwise, he was completely normal. Since the time of the surgery, more than five decades of scrupulous neuropsychological research examined the nature of patient H.M.'s amnesia which proved to be both persistent and remarkably selective.

• The goal of our project is to provide a window into the brain of the man who helped establish the scientific study of memory and unfailingly forgot the enormously generous contribution he made to medical research.

• Check out “Project HM”: http://thebrainobservatory.ucsd.edu/hm

Brain of an Amnesiac (Large Loss of Hippocampus)

Amnesiac Performance on Implicit Memory Tasks

Squire et al. 1987

Amnesiac Performance on Explicit Memory Tasks

This is data from patient HM

Memory Tests in Non-Humans

• Morris Water

Maze

Hippocampal-Lesioned Mice Perform Poorly on MWM

Hippocampal-Lesioned Mice Perform Poorly on MWM

Neural Control of Memory

Medial Temporal Lobe Striatum Neocortex

Dementia

• It’s a syndrome, not a disease

• Multiple types of dementia across a spectrum of severity– Alzheimer’s, HIV-induced,

Parkinson’s, Rasmussen’s encephalitis, chronic traumatic brain injury, to name a few

Alzheimer’s DiseaseNeuronal Identifier #1: Neurofibrillary Tangles

Alzheimer’s DiseaseNeuronal Identifier #2: Beta-amyloid Plaques