Hemispheric Specialization, Split-Brain Research, and Memory Systems

Vocabulary flashcards summarizing key terms from the lecture on hemispheric processing, split-brain research, neuroplasticity, and the neural basis of explicit and implicit memory.

Hemispheric Specialization

The tendency for certain cognitive functions (e.g., language) to be more dominant in one cerebral hemisphere, though with considerable redundancy across both sides.

Split-Brain Surgery (Corpus Callosotomy)

A procedure that severs the corpus callosum, isolating the two hemispheres and preventing most inter-hemispheric communication.

Corpus Callosum

The large bundle of neural fibers connecting the left and right cerebral hemispheres; its severance produces a split-brain.

Contralateral Visual Field

The principle that stimuli presented to the left visual field project to the right hemisphere and vice-versa.

Bilateral Eye Projection

Each eye sends information to both hemispheres; closing one eye does NOT restrict input to a single hemisphere.

Left Hemisphere

Brain hemisphere typically dominant for language and conscious verbal reporting in most right-handers.

Right Hemisphere

Brain hemisphere specialized for spatial, holistic processing and limited language; controls the left hand and often operates non-consciously.

Neuroplasticity

The brain’s ability to reorganize and form new neural connections, allowing functions to shift after injury or learning.

Motor Homunculus

The cortical map in the primary motor cortex showing which body parts are controlled by each brain region; discovered by Wilder Penfield.

Somatosensory Homunculus

The adjacent parietal-lobe map that represents where tactile sensations from each body region are processed.

Wilder Penfield

Neurosurgeon who mapped motor and sensory cortices with cortical stimulation and showed that stimulation can evoke vivid memories.

Cortical Stimulation

Application of a mild electrical current to an exposed brain area during surgery to identify its function.

Memory Circuit

A distributed network of neurons whose coordinated activity gives rise to a specific memory; not confined to a single locus.

Explicit (Declarative) Memory

Consciously accessible memories of facts (semantic) and personal events (episodic); initially hippocampus-dependent.

Implicit (Non-Declarative) Memory

Unconscious memories such as skills, priming, and conditioning that do not require the hippocampus.

Hippocampus

Medial-temporal lobe structure crucial for encoding new explicit memories; one in each hemisphere.

Ribot’s Law

In amnesia, older memories are more likely to be preserved than recent ones.

Nomadic Memory

Concept that the neural representation of a memory ‘moves’; hippocampus is needed early but not for remote memories.

Anterograde Amnesia

Inability to form new explicit memories after brain damage (e.g., hippocampal removal).

Henry Molaison (H.M.)

Patient who lost hippocampi in 1953 surgery, yielding profound anterograde amnesia but intact earlier memories.

Clive Wearing

Musician whose viral encephalitis damaged his hippocampi, leaving him with seconds-long memory span but preserved early life knowledge.

Optic Chiasm

The subcortical crossover point of optic nerves ensuring each visual field projects contralaterally, even after corpus callosum section.

Medial Temporal Lobe Memory System

Cluster of structures (hippocampus, entorhinal, perirhinal, parahippocampal cortices) that cooperate in explicit memory encoding.