Brain Anatomy Vocabulary

Central Nervous System (CNS)

• Comprises the brain and spinal cord.
• The brain contains approximately 100 billion neurons.
• Neurons form complex neural circuits with distinct pathways.

Neuron Structure

• Soma (Cell Body): Contains the nucleus.
• Dendrites: Finger-like projections extending from the soma, receiving information from other neurons.
• Axon: Fiber through which a cell transports information to other cells.
• Axon Terminals: Branched features at the end of the axon that form synapses (communication points) with dendrites or cell bodies of other neurons.

Brain Structure and Function

• Understanding brain structure is crucial in relating specific brain parts to psychological disorders.
• An evolutionary perspective helps understand the development of brain regions and their functions.

Brainstem

• The oldest part of the brain, controlling fundamental biological functions like breathing.
• Consists of the hindbrain (medulla, pons, cerebellum).

Hindbrain

• Medulla, Pons, Cerebellum: Regulate automatic life-sustaining activities such as breathing, heartbeat, and motor control.
• Cerebellum: Critical for motor coordination; lesions result in disorders of fine movement, balance, and motor learning.

Lesions

• Areas of damage or abnormality in the brain.
• Studying the effects of lesions helps in understanding the function of specific brain structures.

Midbrain

• Functions:
  • Coordinating center integrating sensory information with movement.
  • Contains the reticular activating system, which regulates sleep and arousal.

Thalamus and Hypothalamus

• Located structurally and evolutionarily above the brainstem.

Thalamus

• Acts as the brain's relay station, directing sensory information to the cortex.
• Example: Like an airline hub (e.g., Dallas), sensory information is first sent to the thalamus, then directed to the appropriate area of the cortex.

Hypothalamus

• Primary function: Homeostasis, regulating bodily functions such as:
  • Blood pressure
  • Body temperature
  • Fluid and electrolyte balance
  • Body weight

Limbic System

• Located in the forebrain, above the midbrain.
• Includes the amygdala, cingulate gyrus, and hippocampus.
• Deals primarily with emotions and impulses.
• Involved in:
  • Experiencing emotion
  • Regulating emotional expression
  • Basic biological drives such as aggression, sex, and appetite.

Hippocampus

• Plays a role in memory formation.
• Linked to memory deficits in Alzheimer's disease.

Basal Ganglia

• Located at the base of the forebrain.
• Structures include caudate, putamen, nucleus accumbens, globus pallidus, substantia nigra, and subthalamic nucleus.
• Generally inhibit movement.
• Diseases affecting the basal ganglia are characterized by abnormal movements (e.g., Parkinson's disease, Huntington's disease).

Cerebral Cortex

• Largest part of the forebrain.
• Enables reasoning, abstract thought, perception of time, and creativity.
• Divided into left and right hemispheres.

Hemispheres

• Left Hemisphere:

  • Responsible for language and cognitive functions.
  • Processes information linearly and logically.
  • Processes information sequentially, using language and symbols including numbers.

• Right Hemisphere:

  • Processes the world holistically and in a spatial context.
  • Associated with creativity, imagery, and intuition.

• Communication occurs between hemispheres, and they can compensate for each other.

Case Study: Henry Molaison (H.M.)

• Underwent surgery in 1953 where parts of his medial temporal lobe were removed to treat severe seizures.
• Developed anterograde amnesia (inability to form new long-term memories).
• Could recall short-term memories and long-term memories from before the operation.
• His case led to two key findings:
  • Short-term memories do not depend on a functioning hippocampus.
  • Long-term memories must pass through the hippocampus to be permanently stored.

Lobes of the Cerebral Cortex

• Each hemisphere consists of four lobes: temporal, parietal, occipital, and frontal.
  • Temporal Lobe:
    • Associated with processing auditory and visual information.
    • Plays a role in naming/labeling objects and verbal memory.
  • Parietal Lobe:
    • Integrates sensory information from various sources.
    • Involved with visuospatial processing (e.g., imagining rotating a 3D object).
  • Occipital Lobe:
    • Located at the back of the skull.
    • Center of visual processing.
  • Frontal Lobe:
    • Seat of reasoning.
    • Critical role in impulse control, judgment, language, memory, motor function, problem-solving, and social/sexual behavior.
    • Instrumental in planning, coordinating, inhibiting, and executing behavior.

Corpus Callosum

• Connects the two hemispheres, allowing communication.
• Severing it can lead to an inability to integrate certain brain functions (e.g., not being able to name an object flashed in the right field of vision).

Peripheral Nervous System (PNS)

• Subdivided into:
  • Sensory-somatic nervous system
  • Autonomic nervous system

Sensory-Somatic Nervous System

• Consists of cranial nerves that control sensation and muscle movement.

Autonomic Nervous System

• Includes the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System (SNS)

• Primarily controls involuntary movements.
• Activates the body, creating a state of physical arousal.
• Effects:
  • Stimulates heartbeat
  • Raises blood pressure
  • Dilates pupils
  • Diverts blood from skin and inner organs to skeletal muscles, brain, and heart
  • Inhibits digestion and peristalsis

Parasympathetic Nervous System

• Returns the body functions to resting levels after SNS activation.

Endocrine System

• Regulates bodily functions using hormones.
• Endocrine glands produce hormones, which are chemical messengers released into the bloodstream, acting on target organs.

Glands

• Pituitary Gland:
  • Located at the base of the brain.
  • The master gland that controls many endocrine functions, including those central to the menstrual cycle, pregnancy, birth, and lactation.
• Hypothalamus:
  • Regulates the pituitary gland.
• Adrenal Glands:
  • Located on top of the kidneys.
  • Release epinephrine in response to external and internal stressors.
• Thyroid Gland:
  • Regulates metabolism, including body temperature and weight.
• Pancreas:
  • Secretes insulin and glucagon to regulate blood sugar levels.

Hormones and Psychological Symptoms

• Studies show certain hormones are elevated in people with depression, anxiety, and other psychological symptoms.