Hockenbury Discovering Psychology 5th txtbk

66 CHAPTER 2 Neuroscience and Behavior“We’ve always known that our brainscontrol our behavior, but not that ourbehavior could control and change thestructure of our brains.”FRED GAGE (2007)The BrainstemHindbrain and Midbrain StructuresKey Theme• The brainstem includes the hindbrain and midbrain, located at the base ofthe brain.Key Questions• Why does damage to one side of the brain affect the opposite side of thebody?• What are the key structures of the hindbrain and midbrain, and what aretheir functions?brainstemA region of the brain made up of the hindbrainand the midbrain.hindbrainA region at the base of the brain that containsseveral structures that regulate basiclife functions.The major regions of the brain are illustrated in Figure 2.13, which can serve as amap to keep you oriented during our tour. At the base of the brain lie the hindbrainand, directly above it, the midbrain. Combined, the structures of the hindbrain andmidbrain make up the brain region that is also called the brainstem.The HindbrainThe hindbrain connects the spinal cord with the rest of the brain. Sensory andmotor pathways pass through the hindbrain to and from regions that are situatedhigher up in the brain. Sensory information coming in from one side of the bodycrosses over at the hindbrain level, projecting to the opposite side of the brain. Andoutgoing motor messages from one side of the brain also cross over at the hindbrainlevel, controlling movement and other motor functions on the opposite side of thebody. This is referred to as contralateral organization.Contralateral organization accounts for why people who suffer strokes on oneside of their brain experience muscle weakness or paralysis on the opposite side ofFigure 2.13 Major Regions ofthe Brain Situated at the base ofthe brain, the hindbrain’s functionsinclude coordinating movementand posture, regulating alertness,and maintaining vital life functions.The midbrain helps process sensoryinformation. In combination, thehindbrain and the midbrain comprisethe brainstem. The forebrainis the largest brain region and isinvolved in more sophisticatedbehaviors and mental processes.ForebrainUppermost and largestbrain regionCorpus callosum:Thick band of axons connectingthe two hemispheres of thecerebral cortexCerebral cortex:Divided into two hemispheresand responsible forsophisticated mental functionsMidbrainContains structuresinvolved in processingvisual and auditoryinformationHindbrainRegion at base of brainthat connects the brain tothe spinal cordPons:Helps coordinatemovements on left andright sides of bodyCerebellum:Coordinates movement,balance, and postureReticular formation:Helps regulate attentionand alertnessMedulla:Controls breathing,heartbeat, and othervital life functions