Parts of the Brain - Structure & Functions

Hemispheres

  • The left hemisphere controls the right side of the body, and the right hemisphere controls the left side.
  • The two hemispheres always work together.

Corpus Callosum

  • Bundle of nerve fibers connecting the two hemispheres.
  • Facilitates the movement of messages from one side of the brain to the other.

Lateralization

  • Each hemisphere has distinct functions.
    • Left Hemisphere: Specializes in language, speech, handwriting, calculation, time and rhythm sense, and analytical thought.
    • Right Hemisphere: Specializes in perception, visualization, spatial perception, pattern recognition, faces, emotions, melodies, and emotional expression.
  • Myth: Being either “left-brained” or “right-brained.
  • Fact: Both hemispheres contribute to achievements; individuals are not solely defined by one side.

Cerebral Cortex

  • Outer layer of the brain, responsible for higher thought, language, and consciousness.
  • Gray matter: Neural cell bodies, axon terminals, dendrites, and nerve synapses.
  • White matter: Conducts nerve signals up and down the spinal cord.

Lobes

  • Areas of the cerebral cortex with specific locations and primary functions.

Frontal Lobes

  • Located at the front and top of the brain; associated with reasoning, motor skills, higher-level cognition, and expressive language.
Frontal Lobe Association Areas
  • Prefrontal Cortex: Planning complex cognitive behavior, personality expression, decision-making, and moderating social behavior.
  • Motor Cortex: Receives information from various lobes for carrying out body movements.
  • Broca’s Area: Controls motor functions involved in speech production and language comprehension, located in the left frontal lobe.

Parietal Lobes

  • Located at the top and back of each cerebral hemisphere; processes sensory signals such as touch, pressure, temperature, and pain.
Parietal Lobes Association Area
  • Somatosensory Cortex: Receives and processes sensory information from the entire body.

Occipital Lobes

  • Located at the rear and bottom of each cerebral hemisphere; contains the visual centers of the brain.
  • Information from the left visual field is processed in the right occipital lobe, and vice versa.
  • Visual Association Cortex: Recognizes lines, angles, shapes, shadows, and movement.

Temporal Lobe

  • Located behind the temples; contains neurons responsible for hearing and meaningful speech.
  • Wernicke’s Area: Located in the temporal lobe on the left side; responsible for speech comprehension. Plans for meaningful speech are created here.

Brainstem

  • Most primitive part of the brain, connected to the spinal cord.
  • Controls the flow of messages between the brain and the body.
  • Regulates basic body functions such as breathing, swallowing, heart rate, blood pressure, and consciousness.

Medulla Oblongata

  • Located at the top of the spinal cord; controls autonomic functions such as heart rate, breathing, and blood pressure.
  • Fibers cross here, resulting in contralateral control.

Pons

  • Connects the top of the brain to the bottom; bridge between cerebral hemispheres and both medulla & cerebellum.
  • Role in autonomic functions such as stimulating breathing and controlling sleep cycles.

Reticular Formation

  • Network of nerves that carry messages between parts of the brainstem.
  • Regulates pain intensity and controls some parts of the body.
  • Helps focus on useful sensory input while filtering out unnecessary stimuli.

Cerebellum

  • Helps control posture, balance, and coordination of voluntary movements.

Thalamus

  • Processes and transmits movement and sensory information; sensory relay station of the brain.
  • Receives information from all senses and routes it to higher brain regions.

Limbic System

  • Network of structures located beneath the cerebral cortex.
  • Coordinates emotions, basic drives, and the formation of episodic memories.

Hypothalamus

  • Connects with many other brain regions; controls hunger, thirst, emotions, body temperature regulation, and circadian rhythms.
  • Controls the pituitary gland by secreting hormones.

Hippocampus

  • Critical role in forming, organizing, and storing new memories, and connecting sensations and emotions to memories.

Amygdala

  • Primarily involved in processing emotion and survival responses.
  • Active during potentially threatening situations; influences aggression and fear.