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Brain Imaging Techniques and Brain Structures - Vocabulary Flashcards

Lesions, Imaging, and Brain Structures

  • Lesion

    • A lesion is tissue destruction of the brain, which can be natural or experimentally produced.

    • It represents a destroyed or damaged area of brain tissue.

  • Neuroimaging and recording techniques

    • EEG (electroencephalogram)

    • An amplified readout of the brain's electrical activity.

    • Wave activity sweeps across the brain's surface and is measured by electrodes placed on the scalp.

    • CT / CAT Scan (computed tomography)

    • A series of X-ray photographs taken from different angles.

    • Computers combine them into a composite representation of a brain slice.

    • Can reveal brain damage.

    • PET (positron emission tomography) scan

    • A visual display of brain activity.

    • Detects where a radiolabeled form of glucose goes while the brain performs a task.

    • Depicts brain activity by showing areas of glucose consumption by active neurons.

    • MRI (magnetic resonance imaging) scan

    • Uses magnetic fields and radio waves to produce computer-generated images of soft tissue.

    • Shows brain anatomy.

    • fMRI (functional MRI)

    • Reveals blood flow and therefore brain activity by comparing successive MRI scans.

    • Scans show brain function and structure.

    • Two halves of the brain are involved; detects where blood and oxygen go during activity.

  • Important detail about imaging and interpretation

    • Ventricles are fluid-filled areas of the brain.

    • Enlarged ventricles observed in schizophrenia (as noted in the transcript; association described rather than a definitive diagnostic rule).

Brain Structures and Core Functions

  • Brainstem (oldest part of the brain's central core)

    • Located where the spinal cord swells as it enters the skull.

    • Functions include automatic survival processes.

  • Key components:

    • Medulla: base of the brainstem; controls heartbeat and breathing.

    • Pons: located above the medulla; helps coordinate movements and serves as a bridge in the brain.

    • Reticular formation: a nerve network traveling through the brainstem and thalamus; plays a role in controlling arousal.

  • Thalamus

    • The brain's sensory control center; located at the top of the brainstem.

    • Directs messages to the sensory areas of the cortex and transmits replies to the medulla and cerebellum via connections in the brainstem.

    • Works with the reticular formation to influence arousal.

  • Cerebellum (the "little brain")

    • Located at the rear of the brainstem.

    • Functions include:

    • Processing sensory input.

    • Coordinating movement output and balance.

    • Enabling nonverbal learning and memory.

  • Cerebral hemispheres

    • Two halves of the brain.

  • Limbic System

  • Neural system located below the cerebral hemispheres.

    • Includes amygdala, hippocampus, and hypothalamus.

    • Associated with emotions and drives.

  • Hippocampus

    • Processes conscious memory.

  • Amygdala

    • Two clusters linked to emotions.

    • Associated with aggression and fear.

  • Hypothalamus

    • Lies below the thalamus.

    • Directs maintenance activities (eating, drinking, body temperature).

    • Helps govern the endocrine system via the pituitary gland.

    • Linked to emotion and reward.

  • Reward system and implications

    • The hypothalamus is involved in the reward system.

    • Addictive disorders may root from a reward deficiency syndrome (as referenced in the transcript).

Connections and Implications

  • Imaging and diagnosis

    • Different imaging modalities provide complementary information:

    • Structure (MRI, CT) vs. function (PET, fMRI).

    • Electrophysiological activity (EEG) offers temporal dynamics of brain waves.

    • Enlarged ventricles observed in schizophrenia suggest structural differences related to this condition, though imaging findings are not definitive diagnostics on their own.

  • Functional vs. structural anatomy

    • Structure-focused imaging (MRI) reveals anatomy; functional imaging (fMRI, PET) reveals activity patterns and metabolic processes.

    • The brain's core regulatory and arousal systems involve the brainstem and reticular formation, illustrating how basic life-support and alertness are integrated with higher cognitive functions.

  • Ethical and practical considerations

    • Neuroimaging findings must be interpreted carefully within clinical context to avoid over-interpretation (e.g., ventricle size and schizophrenia linkage).

    • In research, lesion studies (natural or experimental) can reveal causal roles of brain regions but require ethical considerations around safety and consent.

  • Quick reference: key terms and definitions

    • Lesion: Tissue destruction in the brain, natural or experimentally produced.

    • EEG: Electrical activity recording across the scalp.

    • CT/CAT: X-ray-based structural brain imaging.

    • PET: Metabolic imaging using radiolabeled glucose.

    • MRI: Structural imaging using magnetic fields and radio waves.

    • fMRI: Functional imaging via blood flow and oxygenation.

    • Ventricles: Fluid-filled brain cavities.

    • Thalamus: Sensory relay and arousal integration center.

    • Medulla: Budding life-support functions (heartbeat, breathing).

    • Pons: Bridge for movement coordination.

    • Reticular formation: Arousal and alertness system.

    • Cerebellum: Movement coordination and nonverbal learning.

    • Limbic system: Emotion, memory, and drives.

    • Hippocampus: Conscious memory formation.

    • Amygdala: Emotion processing (fear, aggression).

    • Hypothalamus: Maintenance functions, endocrine control, reward.