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1.4 The Brain

Learning objectives

1.4A—Explain how the structures and functions of the brain apply to behavior and mental processes. UNIT 1 Biological…Explain how the structures and functions of the brain apply to behavior and mental processes. UNIT 1 Biological Bases of Behavior• The brain stem (including the medulla) generally controls basic functioning such as breathing and heart rate.• The reticular activating system and the brain’s reward center generally control alertness, some voluntary movement, eye movement, and some types of learning, cognition, and emotion.• The cerebellum generally controls coordination of muscle movement, balance, and some forms of procedural learning.• The cerebral cortex is divided into two hemispheres and includes the limbic system (thalamus, hypothalamus, pituitary gland, hippocampus, amygdala), corpus callosum, and the lobes of the cortex.- i. The occipital lobes generally control visual information processing and are located in the rear of the brain.- ii. The temporal lobes generally control auditory and linguistic processing and are located on the sides of the brain.- iii. The parietal lobes generally control association areas, which process and organize information, and the somatosensory cortex, which processes touch sensitivity. These lobes are located near the back crown of the brain.- iv. The frontal lobes, located just behind the forehead, generally control linguistic processing, higher-order thinking, and executive functioning, especially in the prefrontal cortex. The motor cortex is located at the rear of the frontal lobes and controls most types of skeletal movement.• Split brain research, achieved by severing the corpus callosum (often a treatment for severe epilepsy), reveals that the right and left hemispheres of the brain may specialize in different activities and functions.- i. Areas of the brain that affect language are typically located in the left hemisphere and include Broca’s area (responsible for speech production) and Wernicke’s area (responsible for speech comprehension). Damage to these parts of the brain can lead to aphasia.- ii. Researchers test for cortex specialization with split-brain patients by showing information in each visual field, taking advantage of the brain’s contralateral hemispheric organization.• Brain plasticity is the ability of the brain to rewire itself or modify or create new connections throughout development and generally allows for the function of a damaged part of the brain to be assumed by a different part of the brain.• Research on the brain is done using scans (including EEG and fMRI), case studies, and surgical procedures (such as lesioning) to promote understanding of how the different structures of the brain work and how the brain functions together as a whole.

Brain structures specialize in broad functions but operate as an interacting whole. A structure–function claim connects a physical area with a pattern of behavior or mental processing; it does not mean that the area works alone.

Structure	General functions in the CED
Brain stem, including medulla	Basic functions such as breathing and heart rate
Reticular activating system and reward center	Alertness, some voluntary and eye movement, and some learning, cognition, and emotion
Cerebellum	Coordination of muscle movement, balance, and some procedural learning
Cerebral cortex	Two hemispheres containing the limbic system, corpus callosum, and cortical lobes
Limbic system	Includes thalamus, hypothalamus, pituitary gland, hippocampus, and amygdala

Cortical area	Location	General function
Occipital lobes	Rear	Visual information processing
Temporal lobes	Sides	Auditory and linguistic processing
Parietal lobes	Near the back crown	Association processing and organization; somatosensory touch processing
Frontal lobes	Behind the forehead	Linguistic processing, higher-order thinking, and executive function; the rear motor cortex controls most skeletal movement

The corpus callosum connects the hemispheres. In split-brain research, severing it—often to treat severe epilepsy—allows researchers to present information to different visual fields and test contralateral hemispheric specialization. Language is typically left-lateralized: Broca’s area supports speech production and Wernicke’s area supports speech comprehension; damage can produce aphasia. Localization is not completely fixed, however. Brain plasticity allows connections to be modified or created across development and may allow another area to assume a damaged area’s function.

Researchers combine EEG and fMRI scans, case studies, and surgical procedures such as lesioning to infer how structures function individually and together. A scan, damaged area, or single case provides evidence—not proof that one structure alone causes a complex behavior.

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