User:Richard E. Hartman:Courses:Learning and Memory: Difference between revisions
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* spatial learning requires only a small portion of functional tissue in the dorsal hippocampus | * spatial learning requires only a small portion of functional tissue in the dorsal hippocampus | ||
===CLASS 6=== | ===CLASS 6 (detailed)=== | ||
*we can learn more about a stimulus when it is easily perceived | |||
**increased experience with stimuli allows such enhanced perceptions to occur | |||
**“the more you know, the more you can learn” | |||
**perceptual fluency – the ability to quickly distinguish one stimuli from another | |||
*presentation of varying degrees of contrasting stimulus categories leads to effective understanding of items | |||
**once easy discrimination can be made, more subtle ones are easier | |||
**learning to discriminate between stimuli generally requires some type of “attention” | |||
*nervous system is a big mass of biological tissue composed of interconnected neurons | |||
**parallel and serial networks within massively parallel networks | |||
**hierarchy: Spinal cord / Hindbrain / Midbrain / Diencephalon / Basal ganglia / Neocortex | |||
***primary motor / sensory | |||
***secondary motor / sensory | |||
***association | |||
*individual cortical neurons arranged into layers and columns | |||
*6 layers: | |||
**layer 4 is mostly sensory inputs (lots of dendrites) | |||
**layer 5/6 are mostly outputs (lots of long axons out) | |||
**columns are arranged “topographically” into “maps” of various parts of our body | |||
**each mapped area processes certain aspects of incoming data before passing it to other areas | |||
*sensations cause changes in spatiotemporal patterns of the cortical activity | |||
** we experience this as our “perception” of reality | |||
*receptors are specialized neurons for transducing information from the physical environment into chemical and electrical signals (sensations) | |||
*Receptive sheet | |||
**receptors innervate very specific regions | |||
**area which a sensory system innervates = receptive sheet | |||
**somatosensory receptive sheet is total body surface | |||
**visual receptive sheet is the retina | |||
*Receptive field - that portion of the environment to which a receptor (or cortical neuron) will respond | |||
**each rod or cone has a precise receptive field | |||
**each subsequent neuron also has a receptive field | |||
**convergence / divergence at each subsequent synapse creates larger / more complex receptive fields | |||
**increased coding and abstraction of “information | |||
*receptors send info about the external world through the thalamus (sensory relay station) to several areas of primary sensory cortex | |||
*What is the nature of “information” sent to the cortex? | |||
**Qualitative - “what is it?” | |||
***labeled line - chain of neurons that results in a sensation | |||
**Quantitative - “how much?” | |||
***frequency coding - rate of APs | |||
***population coding - # of receptors firing | |||
**Adaptation - response of a neuron to constant stimulation | |||
***phasic - quickly adapting | |||
***tonic - slowly adapting | |||
*By the time info gets to cortex, some elaborate processing is already taking place | |||
**distinct regions of cortex respond (increase firing rate) to small, specific region of the sensory field | |||
**cortical neurons have overlapping receptive fields | |||
**adjacent neurons represent adjacent parts of the field | |||
**receptive fields are organized in a “topographic map” of the sensory field | |||
*in addition to overlapping topographic map of the receptive sheet, certain neurons also respond preferentially to specific trigger features | |||
*individual columns arranged into microcircuits of ~1 mm sq hypercolumns | |||
**ocular dominance columns | |||
**orientation columns | |||
**“color” blob | |||
***responses of individual neurons are probabilistic (and relatively unimportant) | |||
*within each sensory area, there exists a hierarchy of larger circuits representing increasingly more complex processing of incoming sensory information | |||
**visual cortex encompasses almost all of the occipital lobe and parts of the parietal & temporal | |||
**serial and parallel connections | |||
**there is as much backward flow as forward flow | |||
**early, lower, “upstream” areas | |||
***identifying basic properties of stimuli | |||
****orientation | |||
****spatial frequency | |||
****speed | |||
****color | |||
****location | |||
**later, higher, “down-stream” levels of processing | |||
***“maps” get fuzzier higher in the cortical hierarchy | |||
***response properties of these cells more complex | |||
***arise from combinations of inputs from lower levels | |||
****what (ventral) streams - “categorization” (faces, hands, etc.) | |||
****where (dorsal / parietal) - localizing in 3D space | |||
****higher levels of processing networks connect with each other in association cortex (multimodal, association cortex) | |||
****these multimodal areas send outputs to areas in the frontal, temporal and parietal cortices AND the hippocampus | |||
*cells change firing patterns with experience | |||
**less activity for repeated stimuli | |||
**processing is “easier” / less effort | |||
**not only “cellular” mechanisms, but “network”-level mechanisms | |||
*Learning / Memory is completely intertwined with sensory / perceptual processing | |||
**early experience (both external and internal) guides the development of the general organization of cortical circuitry | |||
**experience driven “tuning” / modification | |||
**response properties are plastic | |||
**like muscles, using circuits changes their operation | |||
**experience alters the structure and function of the circuits | |||
*constantly changing dynamic chemical bath | |||
**this ball of cells detects stuff in the environment that causes transient changes in the pulsation frequencies | |||
**produces constantly changing dynamic electrical patterns | |||
**sensations cause changes in spatiotemporal patterns of the cortex – we experience this as our “perception” of reality | |||
**different networks naturally tend to “pulse” at different frequencies | |||
**areas that are active at the same time tend to become more strongly connected (and vice versa) | |||
**HEBB - “fire together / wire together” via functional and structural changes | |||
**activity in 1 area is more likely to induce activity in connected areas | |||
*the biological basis of learning is thought to depend in part upon the ability of neurons to modify their synaptic connections within neural circuits based on experience | |||
*memory retrieval happens when we re-experience same or similar spatiotemporal patterns in cortical activity | |||
*cortex is “reorganized” during “learning”: | |||
**train specific fingers to perform sensory tasks | |||
*Learning / Memory is the behavioral and psychological consequence of changes in sensory / information processing | |||
**psychophysical monism | |||
**neurons are adaptive - can shift or modify response to stimuli based on previous experiences with that stimuli | |||
===CLASS 7=== | ===CLASS 7=== |
Revision as of 14:24, 9 November 2009
LLU PSYC 544: Foundations of Learning and Behavior