Karl Lashley & Donald Hebb: Brain & Memory

Karl S. Lashley

• Two important observations regarding cortex function were made.
• Mass action: Ability loss after cortex destruction depends on the amount, not location, suggesting a unified cortex.
• Equipotentiality: Any part of a functional brain area can perform the function of that area
• Engram refers to the neurophysiological locus of memory and learning.
• Lashley spent decades searching for the engram and eventually conceded that it was not locatable.

Donald O. Hebb

• Neural interconnections develop with experience.
• Every experienced environmental object fires a complex package of neurons, called a cell assembly.
• Reverberating neural activity allows for the association of temporarily separated neurons.
• Cell assemblies neurologically integrate to form phase sequences
• Phase sequence: a temporally integrated series of assembly activities; it amounts to one current in the stream of thought.
• Childhood learning uses a slow buildup of cell assemblies and phase sequences.
• This buildup can be explained using associationistic terminology.
• Adult learning is characterized by creativity, insight and rearrangement of already existing cell assemblies and phase sequences.
• Animals in enriched sensory environments were relatively better learners as adults
• Activity level in the reticular activating system (RAS) relates to cognitive and behavioral performance.
• Reinforcement centers exist in the brain

Roger W. Sperry

• Split-brain preparation involves cutting the corpus callosum and optic chiasm to effectively split the brain.
• Early split-brain experiments were done with animals.
• Cutting the corpus callosum helps reduce the intensity of seizures by stopping propagation between hemispheres in people with drug-resistant epilepsy.
• Research on human subjects with cut corpus callosum has contributed to knowledge of hemispheric specialization.
• There is caution in too much speculation regarding specialization and its impact on learning and educational practices.
• Sperry was an interactionist concerning the mind-body problem.
• Consciousness emerges from brain processes and once emerged has a causal relationship to behavior.

Ethology

• The study of instinctive animal behavior.
• Ethologists study specific categories of behavior within an animal's natural environment and try to explain that behavior in terms of evolutionary theory.
• Species-specific behavior examines how members of a species typically behave under specific environmental conditions.

Evolutionary Approaches

• Sociobiology attempts to explain complex social behavior in terms of evolutionary theory.
• Biogrammar is inherited structures that predispose organisms toward certain kinds of social activities.
• The leash principle says there is a close relationship between culture and the satisfaction of biological needs and biology holds culture on a leash
• Sociobiology and evolutionary psychology are terms used interchangeably.
• There is criticism for accepting adaptionism
• Exaptation and Spandrels is a terminology
• "Misbehavior" of organisms and instinctual drift have been studied
• Researchers have found support for the finding that within a given species, some associations are easier to establish than others
• The Preparedness continuum explains that different animals are biologically prepared to form certain associations and contraprepared to form others; this is selected for through evolutionary principles.

Behavioral Genetics

• Behavioral genetics is the branch of psychobiology that studies the genetic influence on cognition and behavior.
• Thomas Bouchard conducted twin research.
• Heritability shows the extent to which variations on a trait or attributed are attributable to genetics.
• Various researchers have investigated the heritability of intelligence and personality characteristics.
• There is still much argument and discussion regarding these highly sensitive subjects.