CSE511 Brain & Memory Modeling Lect 22,24,25: Memory Systems Compare Chap 31 of Purves et al., 5e Chap 24 of Bear et al., 3e Larry Wittie Computer Science, StonyBrook University http://www.cs.sunysb.edu/~cse511 and ~lw 11/12,19,21/13 Lect22,24,25 Memory Systems 1
Neuroscience: Exploring the Brain 3e Chapter 24: Memory Systems Slide 2
Introduction Learning and remembering distinguishes naïve from mature brain Relationship between visual development and learning Similar mechanisms in different cortical areas Memories range from stated facts to ingrained motor patterns Anatomy: Several memory systems Evident from brain lesions Slide 3
Types of Memory and Amnesia Learning Acquisition of new information Memory Retention of learned information The way information is stored may change over time Declarative memory (explicit) Facts and events Nondeclarative memory (implicit) Procedural memory- skills, habits, behaviors Slide 4
Types of Long-Term Memory Slide 5
Types of Memory and Amnesia Amnesia Amnesia: Serious loss of memory and/or ability to learn Causes: Concussion, chronic alcoholism, encephalitis, brain tumor, or stroke Common amnesia: Limited amnesia Dissociated amnesia: Amnesia, no other cognitive deficit (rare) Slide 6
Types of Memory and Amnesia Amnesia (Cont d) Memory loss related to time Retrograde amnesia Forget things you already knew Anterograde amnesia Inability to form new memories Transient global amnesia: Shorter period Symptoms: Disoriented, ask same questions repeatedly; Attacks subside in couple of hours; Permanent memory gap Slide 7
The Search for the Engram Lashley s Studies of Maze Learning in Rats Figure 24.4 Engram: memory trace Slide 8
The Search for the Engram Hebb and the Cell Assembly External events are represented by cortical cells Cells reciprocally interconnected reverberation Active neurons cell assembly Consolidation by growth process Fire together, wire together Hebb and the engram Widely distributed among linked cells in the assembly Could involve neurons involved in sensation and perception Slide 9
The Search for the Engram Slide 10
The Search for the Engram Localization of Declarative Memories in the Neocortex Experiments macaque monkeys Differentiate objects based on shapes Lesion made in area IT Cannot discriminate Does not remember stimulus Studies in humans Slide 11
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The Search for the Engram Electrical Stimulation of the Human Temporal Lobes Penfield s experiments Electrical stimulation of the temporal lobe Complex sensations Penfield s patients: Sensations like hallucinations, recall past experiences Temporal lobe: Role in memory storage Temporal lobe stimulation Different from stimulation of other areas of neocortex Slide 13
The Temporal Lobes and Declarative Memory Temporal Lobectomy => Retrograde Amnesia Slide 14
The Temporal Lobes and Declarative Memory Medial Temporal Lobes and Memory Processing Slide 15
Medial Temporal Lobes and Memory Processing The Temporal Lobes and Declarative Memory DNMS: Delayed non-match to sample Medial temporal structures: Important for consolidation of memory to form long-term memories Slide 16
The Temporal Lobes and Declarative Memory Medial Temporal Lobes and Memory Processing Medial temporal structures: Important for consolidation of memory Slide 17
The Diencephalon and Memory Processing The Temporal Lobes and Declarative Memory Diencephalon: Brain regions associated with memory and amnesia (outside the temporal lobe) Slide 18
The Temporal Lobes and Declarative Memory The Diencephalon and Memory Processing Korsakoff s Syndrome Symptoms: Confusion, confabulations, severe memory impairment, and apathy Alcoholics: Develop thiamin deficiency Leads to symptoms: Abnormal eye movements, loss of coordination, tremors Treatment: Supplemental thiamin Thiamin deficiency: Structural brain damage Slide 19
The Temporal Lobes and Declarative Memory Memory Functions of the Hippocampus Declarative memory processing or consolidation Long-term memory consolidation => recognition Slide 20
The Temporal Lobes and Declarative Memory Memory Functions of the Hippocampus Role of the medial temporal lobes (rhinal cortex) Declarative memory processing or consolidation Hippocampal lesions: hard to learn efficient path Slide 21
The Temporal Lobes and Declarative Memory Memory Functions of the Hippocampus Morris Water Maze: Learn Where Platform Is Bilateral hippocampal lesions block learning Slide 22
The Temporal Lobes and Declarative Memory Memory Functions of the Hippocampus Spatial Memory and Place Cells Slide 23
Memory Functions of the Hippocampus The Temporal Lobes and Declarative Memory Spatial Navigation in Humans Slide 24
The Temporal Lobes and Declarative Memory Memory Functions of the Hippocampus Spatial, Working, and Relational Memories Relational memory Highly processed sensory information Comes into hippocampus and nearby cortex Figure 24.19 Spatial Navigation Alternative theories of navigation by (a) a spatial map or (b) a series of overlapping relations. Slide 25
The Striatum and Procedural (Habit) Memory Two elements of basal ganglia Striatum Caudate nucleus Putamen Figure 14.11 Rodent Recordings and Lesions in the Striatum Lesions to striatum: Disrupts procedural memory Damaged hippocampal system: Degraded performance on standard maze task Lesion in striatum: Impaired performance of the lighted maze arms task; Double dissociation Slide 26
The Striatum and Procedural (Habit) Memory Habit Learning in Rodent Striatum Slide 27
The Striatum and Procedural (Habit) Memory Habit Learning in Humans and Nonhuman Primates Human striatum plays role in procedural memory Parkinson s destroys substantia nigra, the main input to the striatum Slide 28
The Neocortex and Working Memory The Prefrontal Cortex and Working Memory Primates have a large frontal lobe Function of prefrontal cortex: self-awareness, capacity for planning and problem solving Slide 29
The Neocortex and Working Memory The Prefrontal Cortex and Working Memory II MRI: Imaging Working Memory in the Human Brain Many areas in prefrontal cortex are involved Slide 30
The Neocortex and Working Memory The Prefrontal Cortex and Working Memory III Humans with prefontal cortex (PFC) damage very slowly discover a newly changed card sorting rule Figure 24.25 The Wisconsin card-sorting test. Subjects must sort cards with symbols of various shapes, colors, and numbers, but are not told the sorting rule. They are told only when they do not sort a card properly. They must discover the sorting rule. When they do, the rule is changed. Subjects with PFC injuries keep using a previously correct rule long after the sorting rule has changed. Slide 31
The Neocortex and Working Memory Lateral Intraparietal Cortex (LIP) and Working Memory Area LIP: Guiding eye movements Delayed-saccade task Slide 32
Concluding Remarks Learning and memory Occur throughout the brain Memories Duration, kind of information stored, and brain structures involved Distinct types of memory Different types of amnesia Multiple brain systems for memory storage Engrams in temporal lobe neocortex Physiological basis? Long-term memories: structural basis? Slide 33