Brainstem Functions and Instincts

The Brain and Its Functions

• The most powerful and oldest of our coping brain functions is the reptilian brain, which controls the body's vital functions and includes the brainstem and the cerebellum.
• The brainstem regulates the bodily processes and consists of the medulla, pons, and reticular formation.
• The cerebellum is concerned with the regulation of motor activities and damage to this area results in jerky, poorly coordinated muscle functioning.

The Midbrain and the Limbic Brain

• The midbrain contains an extension of the reticular activating system and primitive centers concerned with vision and hearing.
• The limbic brain emerged in the first mammals and is responsible for recording memories of behaviors that produced agreeable and disagreeable experiences, thus responsible for emotions.
• The main structures of the limbic brain are the hippocampus, the amygdala, and the hypothalamus.

The Hypothalamus and the Thalamus

• The hypothalamus influences reactions ranging from sweating and salivating to shedding tears and changes in blood pressure and plays a vital role in maintaining the body's internal environment at optimal levels.
• The thalamus is the "great relay station" and receives input from all senses except olfaction, performs some preliminary analyses, and then transmits information to other parts of the brain.

The Neocortex

• The neocortex first assumed importance in primates and culminated in the human brain with its two large cerebral hemispheres that play a dominant role.
• The cerebral hemispheres are responsible for the development of human language, abstract thought, imagination, and consciousness.
• The neocortex is flexible and has almost infinite learning abilities and has enabled human cultures to develop.

The Cerebral Cortex

• The cerebral cortex is the outer covering of the cerebral hemispheres and is responsible for the development of human language, abstract thought, imagination, and consciousness.
• Portions of the parietal lobe are involved with visuospatial processing, and damage to this area produces a number of effects depending on whether it is damage to the right or left hemisphere.

The Temporal Lobe

• The temporal lobe plays a key role in hearing and contains a sensory area that receives input from the ears.
• The temporal lobe also plays a role in language comprehension, and damage to this area results in inability to understand spoken words.

The Occipital Lobe

• The primary function of the occipital lobe is visual, and it contains sensory areas that receive input from the eyes.
• Damage to this area affects the person's field of vision, and objects in a particular location can't be seen, but the rest of the visual field may be unaffected.

The Hemispheres

• The two hemispheres of the brain show a considerable degree of lateralization of function, with each specializing in the performance of somewhat different tasks.
• The left hemisphere is the verbal hemisphere, specialized for speech and other verbal tasks, while the right hemisphere specializes in the control of certain motor movements and in the comprehension and communication of emotion.

Research on the Hemispheres

• Scientists gain knowledge of the functions of the hemispheres through studies of individuals whose hemispheres have been isolated due to accidents or surgery for medical reasons.
• They also gain knowledge from studying individuals in whom the two hemispheres are connected in the normal way.
• The corpus callosum connects the two hemispheres and enables corresponding regions of the left and right cerebral hemispheres to communicate.

The Brain and Visual Perception

• Human beings are visual creatures, and we can recognize a number of objects and use this information to react to these objects.
• We possess specialized cells that are equipped for analyzing different aspects of the visual world.
• The information from our eyes arrives at the extrastriate cortex and then divides into two separate streams: the ventral and the dorsal.

The Brain and Speech

• The integration of different regions in the brain allows us to produce and understand speech.
• The Broca's area is crucial for speech production, and damage to this area results in disruption in one's ability to speak.
• The Wernicke's area is responsible for understanding what others are saying, and damage to this area produces three major symptoms: inability to recognize sounds, inability to understand the meaning of words, and inability to convert thoughts into words.

The Brain and Higher Mental Processes

• The brain controls reasoning, problem-solving, planning, and all other higher mental processes.
• The prefrontal cortex plays a key role in reasoning and other higher mental functions.
• Information that enters the brain is processed simultaneously at several points in the brain, and when a complex task enters the brain, it is broken down into several parts and is then processed by different modules of the brain.

Heredity

• Heredity is defined as the biologically determined characteristics passed from parents to their offspring.
• The information of every cell in the body is found in the chromosomes, which contain genetic material called DNA.
• When the sperm and egg cells combine, the genetic material from the male and female combines to form a new cell with 46 chromosomes.