The Brain Module 4

The Biology of Mind

Older Brain Structures  The Brain Stem  CLOSE UP: The Tools of Discovery – Having Our Head Examined  The Thalamus  The Reticular Formation  The Cerebellum  The Limbic System

The Cerebral Cortex  Structure of the Cortex  Functions of the Cortex  The Brain’s Plasticity Our Divided Brain  Splitting the Brain  Right-Left Differences in the Intact Brain

CLOSE UP: The Tools of Discovery – Having Our Head Examined Lesion [LEE-zhuhn]: tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue. Electroencephalogram (EEG): an amplified recording of the waves of electrical activity that sweep across the brain’s surface, measured by electrodes on the scalp.

PET Scan PET (positron emission tomography) Scan is a visual display of brain activity that detects a radioactive form of glucose while the brain performs a given task. Courtesy of National Brookhaven National Laboratories

MRI Scan MRI (magnetic resonance imaging) uses magnetic fields and radio waves to produce computer - generated images of soft tissue, showing brain anatomy. fMRI (functional MRI): technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans, showing brain function. Both photos from Daniel Weinberger, M.D., CBDB, NIMH MRI scan of a healthy individual (left) and a person with schizophrenia (right)

The Brainstem and the Thalamus The brainstem, including the pons and medulla, is an extension of the spinal cord. The thalamus is attached to the top of the brainstem. The reticular formation passes through both structures.

Brainstem

The Medulla [muh- DUL-uh] is the base of the brainstem that controls heartbeat and breathing. 10

11 Brainstem Reticular Formation is a nerve network in the brainstem that plays an important role in controlling arousal.

Brainstem The Thalamus [THAL- uh-muss] is the brain’s sensory switchboard, located on top of the brainstem. It directs messages to the sensory areas in the cortex and transmits replies to the cerebellum and medulla. 12

The Brain  Cerebellum [sehr-uh- BELL-um]  the “little brain” attached to the rear of the brainstem  it helps coordinate voluntary movement and balance

The Brain by the Brain

The Brain

The Limbic System is a neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives. The Limbic System

Amygdala The Amygdala [ah- MIG-dah-la] consists of two lima bean-sized neural clusters linked to the emotions of fear and anger.

Hypothalamus The Hypothalamus lies below (hypo) the thalamus. It directs several maintenance activities like eating, drinking, body temperature, and control of emotions. It helps govern the endocrine system via the pituitary gland.

Rats cross an electrified grid, accepting painful shocks, for self-stimulation when electrodes are placed in the reward (hypothalamus) center. Hypothalamus Reward Center

The Cerebral Cortex  Cerebral Cortex  the intricate fabric of interconnected neural cells that covers the cerebral hemispheres  the body’s ultimate control and information processing center

The Cerebral Cortex The cerebral [seh - REE-bruhl] cortex is the intricate fabric of interconnected neural cells that covers the cerebral hemispheres. The body’s ultimate control and information processing center.

The Cerebral Cortex  Frontal Lobes  involved in speaking and muscle movements and in making plans and judgments  Parietal Lobes  include the sensory cortex  Occipital Lobes  include the visual areas, which receive visual information from the opposite visual field  Temporal Lobes  include the auditory areas

The Cerebral Cortex

Functions of the Cortex The Motor Cortex is the area at the rear of the frontal lobes that control voluntary movements. The Sensory Cortex (parietal cortex) receives information from skin surface and sense organs.

Visual Function The functional MRI scan shows the visual cortex is active as the subject looks at a photo. Courtesy of V.P. Clark, K. Keill, J. Ma. Maisog, S. Courtney, L.G. Ungerleider, and J.V. Haxby, National Institute of Mental Health

More intelligent animals have increased “uncommitted” or association areas of the cortex. Neurons in these areas integrate information. Association Areas

Language: Specialization and Integration Brain areas involved in language processing

Language: Specialization and Integration Aphasia: impairment of language, usually caused by left-hemisphere damage either to Broca’s area or Wernicke’s area. Broca’s area: controls language expression; an area of the frontal lobe, usually in the left hemisphere, directs muscle movements involved in speech. Wernicke’s area: controls language reception; usually in the left temporal lobe, involved in language comprehension and expression.

Specialization & Integration Brain activity when hearing, seeing, and speaking words

Brain Rules from John Medina Exercise boosts brain power 2.The human brain evolved, too. 3.Every brain is wired differently. 4.We don’t pay attention to boring things. 5.Repeat to remember. 6.Remember to repeat. 7.Sleep well, think well. 8.Stressed brains don’t learn the same way. 9.Stimulate more of the senses. 10.Vision trumps all other senses. 11.Male and female brains are different. 12.We are powerful and natural explorers.

Phineas Gage Gage Page

Brain Reorganization  Plasticity  the brain’s capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development  Video

Seven tenets of plasticity  Change can occur only when the brain is in the mood.  Change strengthens connections between neurons engaged at the same time.  Neurons that fire together wire together.  Initial changes are just temporary.  Brain plasticity is a two-way street and we can either drive brain change positively or negatively.  memory is crucial to learning.  motivation is a key factor in brain plasticity.  New skill acquisition is key to plasticity.

Our Divided Brain Our brain is divided into two hemispheres. The left hemisphere processes reading, writing, speaking, mathematics, and comprehension skills. In the 1960s, it was termed as the dominant brain.

Splitting the Brain A procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them.

Split Brain Patients With the corpus callosum severed, objects (apple) presented in the right visual field can be named. Objects (pencil) in the left visual field cannot.

Testing the Divided Brain

Try This! Try drawing one shape with your left hand and one with your right hand, simultaneously. BBC

Right-Left Differences in the Intact Brain People with intact brains also show left-right hemispheric differences in mental abilities. A number of brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carrying out a linguistic task.

Example of Brain Processing Read the following slide silently to yourself as I read it out loud

Eaxmlpe of Pcrocessnig The paomnnehil pweor of the hmuan mnid. Aoccdrnig to a rscheearch sutdy at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is that the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. amzanig huh?