Brain and Nervous System
Identify major brain regions, nervous system divisions, endocrine system links, plasticity, lateralization, and research techniques.
A lesson of AP Psychology, in Biological Bases of Behavior, about 10 minutes.
The Brain and Nervous System
By the end of this lesson, you will be able to describe the structure and function of each brain region, explain lateralization, and describe how the nervous system is organized.
The Nervous System: Overview
Central Nervous System (CNS): brain + spinal cord. The command center.
Peripheral Nervous System (PNS): all nerves outside the brain and spinal cord.
- Somatic NS: voluntary control of skeletal muscles; carries sensory info to CNS
- Autonomic NS:
- Sympathetic: "fight or flight"; mobilizes energy; increases heart rate; dilates pupils; inhibits digestion
- Parasympathetic: "rest and digest"; conserves energy; slows heart rate; promotes digestion
Hindbrain (Brain Stem + Cerebellum)
Medulla oblongata: controls life-sustaining functions — breathing, heart rate, blood pressure. Damage is fatal.
Pons: connects the medulla to the cerebellum; involved in sleep, dreaming, and facial sensation.
Cerebellum ("little brain"): coordinates fine motor control, balance, and procedural learning (learning physical skills). Damage → ataxia (uncoordinated movement).
Reticular formation (reticular activating system): a network throughout the brain stem; controls arousal, alertness, and sleep. Damage → coma.
Limbic System (Emotion and Memory)
Thalamus: the brain's sensory relay station. Almost ALL sensory info passes through the thalamus on its way to the cortex (exception: olfaction, which goes directly to the limbic system — which is why smells are so emotionally evocative).
Hypothalamus: below the thalamus; controls the "four Fs": feeding, fighting, fleeing, and sexual behavior. Also regulates the endocrine system via the pituitary gland (the "master gland").
Hippocampus: critical for forming new declarative memories (facts and events). Damage → anterograde amnesia (can't form new memories). Famous patient H.M. had his hippocampus removed — he could learn new skills (implicit memory) but couldn't form new explicit memories.
Amygdala: processes emotions, especially fear and aggression. Evaluates threats; triggers fear response. Damage → inability to recognize fearful faces; reduced response to threats.
The Cerebral Cortex
The outer layer of the brain; highly developed in humans; responsible for higher thought.
divided into left and right; connected by the corpus callosum (split-brain patients show disconnected hemispheres).