Download Can You Remember My Name? Part 2

COGNITIVE
SCIENCE
17
Can You
Remember
My Name?
Part 2
Jaime A. Pineda, Ph.D.
HIPPO CAMPUS
Hippocampus: The Seahorse
Surrounding areas of hippocampus
(Clark, 2006)
Perirhinal, Entorhinal and Parahippocampal Cortices
Hippocampus Malfunctions
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Severe anterograde amnesia
Mild retrograde amnesia
Problems navigating space
Seizures
Early Alzheimer’s Disease
Hippocampus Functions
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Consolidation of STM to LTM
Spatial and contextual memory
Episodic memory
Declarative memory
Detection of novel stimuli
Neurogenesis
Spatial Navigation
Spatial Navigation (cont.)
Volume of hippocampus
Time as London taxi driver
Age Differences in Maintenance Processes
1400
Older
Younger
Reaction Time
1200
1000
800
600
Memory Load
(Anders, Fozard & Lillyquist, 1972)
Age differences increase with increasing memory set size
L R
L R
Rypma, Prabhakaran, Desmond, & Gabrieli, 2001
Psychology and Aging
Parahippocampus
Trace
Hippocampus
Link
DG
Entorhinal cortex
CA3
CA1
SUB
Perirhinal
cortex
Postrhinal
cortex
Unimodal and polymodal
association areas (frontal,
temporal, and parietal lobes)
Hippocampal model
• Relating hippocampal
structure to episodic
memory function
• Mode shifting between
storage and retrieval
through novelty
detection
• Population dynamics
DG
CA3
Entorhinal cortex
CA1
Parahippocampal model
• Relates parahippocampal
structure to episodic memory
function
• Sensory integration
• ‘Object’ & ‘Context’ input
• Retrieval mechanisms
– free recall
– cued recall
– recognition
Hippocampus
Entorhinal cortex
Perirhinal
cortex
Postrhinal
cortex
Unimodal and polymodal
association areas (frontal,
temporal, and parietal lobes)
subiculum
CA1
Dentate gyrus
CA3
Trisynaptic Circuit
Circuit of Hippocampus Proper
Fimbria fornix (to mammillary bodies)
Hippocampus Cells
Pyramidal Cells
Place cells in
hippocampus
map out the
environment
Place cells respond as a function of external cues
Activity-Dependent Synaptic Plasticity
• Short-term plasticities
– Facilitation (paired pulse facilitation):
100-200 ms; increased Ca++  increased
p(NT release)
– Post-tetanic potentiation: 5-10 sec
– Depression: hundreds of ms – few
minutes; caused by repetitive stimulation
causing a decrease in p(NT release).
Activity-Dependent Synaptic Plasticity
(cont.)
• Long-term plasticities
– Short-term potentiation/depression
– Long-term potentiation/depression
LTP is a persistent increase in synaptic efficacy that can be
rapidly induced
Bliss and Lomo, 1973
NMDA Receptor
• “Detects” simultaneous events
(“AND” gate)
• Gated by combination of voltage and
ligand
– Glu + Gly opens channel to Ca ++,
– Magnesium (Mg++) block
removed by membrane
depolarization
• Mediates learning and memory via
LTP (long term potentiation)
– Involved in process of addiction;
behavioral sensitization, and drug
craving
Learning Induced Changes in
Dendrites
Effects of Increased NMDA Receptors