Chapter 13: The Brain

Beta brain waves

(14-30HZ) regular but not as rhythmic produced from frontal lobe when mentally alert and concentrating

Theta brain waves

(4-7 HZ) irregular, common in infants, abnormal in adults, midbrain inhibits them when awake, present in some mental disorders or servere emotional distres

Delta brain waves

(4HZ or less) seen in deep sleep, indicates brain damage if present when awake

Alpha brain waves

(8-13 HZ) regular and rhythmic best record4ed from parietal and occipital lobes when awake but relaxed with eyes closed

Conversion of short-term to long term memory

1.requires proper functioning of amygaloid body 2. requires hippocampus for formation of short-term memory 3.loss of ability to form short-term memory does not affect long-term memory

Consciousness

Consciousness-a state of arousal in which the brain is aware of the environment.

How does the cerebrum communicate with other brain regions and body parts

Direct pathways go through motor areas of the cerebral cortex, through the thalamus, through the pons to the cerebellum or down the spinal cord signaling to lower motor neurons. Indirect pathways go from the motor centers in brain stem through the spinal cord. Sensory signals from muscles and joints go from spinal cord to cerebellum . others go from the cortex to the thalamus sending corrective feedback to motor areas of the cerebral cortex.

What is hemispheric lateralization

Each hemisphere specializes in performing certain unique functions, a feature known as hemispheric lateralization. This also varies from one person to another. Less pronounced in females.

What are the basal nuclei functions

In general they control voluntary and subconscious skeletal muscle(swinging of arm when walking). They initiate but also suppress unwanted movements. and play a role in emotions and learning. Neural calculators that estimate time, Some regions are involved in memory and emotions. The Amygdala processes fear and helps interpret danger.

What does the basal nuclei include

It is conspicuous centers of cell bodies (gray matter) deep within cerebral white matter. They include the caudate nucleus, the lentiform nucleus, and the amygdala.

Anatomy of the cerebrum

Longitudinal fissure, Transverse fissure, Central sulcus, Precentral gyrus, Postcentral gyrus, Lateral sulcus, Cingulate gyrus; Cerebral lobes: Frontal, parietal, temporal, occipital, insula

How does the limbic system create link between emotions and physiological functions

Pathway: stimulus to cerebrum creates perception, limbic creates emotion, cerebrum becomes aware of emotion while hypothalus stimulates multiple visceral and somatic responses

Location and function of cerebral motor areas

Primary motor area- [frontal lobe] precentral gyrus, premotor area . Motor areas control execution of voluntary movement

Location and function of cerebral sensory areas

Primary somatosensory area- [parietal lobe] postcentral gyrus, somatosensory association area. Sensory areas of cerebral cortex are involved in perception of sensory information

What are the various stages of sleep and benefits

REM sleep and non- REM sleep. Major rest period for the body, no external interaction, easily reversible, brain is active as when awake, sleep inducing factors boost immunity repair metabolic damage in cells, different types of memories are consolidated during sleep. Sufficient sleep is important for learning and performing well on exams.

Cerebral Dominance/ Lateralization

The corpus collosum allows communication between the two hemispheres. Being right or left handed indirectly indicates what cerebral dominance a person has. Each hemisphere controls the body on the opposite sides due to discussation piramids. right handed people have a left hemisphere dominance. Damage to the left side will allow a person to sing well but not give a speech.

What does the size of a cerebral cortex area tell you about the body part it controls

The size of the cerebral cortex area that corresponds to a particular body part is proportional to the complexity of signals it requires regardless of body part size.

Location and function of cerebral association areas

Visual association area-[occipital lobe] auditory association area . Association areas deal with more complex integrative functions such as memory, personality traits, and intelligence.

Reticular formation

actively interacting through ascending tracts

The amygdala plays a key role in

aggression, fear, interpreting facial expressions

Left hemisphere tends to process

analytical skills, reasoning, numerical and scientific skills, spoken and written language, and the ability to use and understand sign language.

Anesthetics

block signals from reaching the reticular formation

Long -term memory

can be converted from short-term memory if information repeated, term encoding, may exist for limitless periods of time, needs to be retrieved occasionally or it can be lost

Commissural tracts

conduct nerve impulses between corresponding gyri from one hemisphere to another.

Cerebral white matter

consists primarily of myelinated axons (3 types)

Association tracts

contain axons that conduct nerve impulses between gyri in the same hemisphere

RAS function

continuosly sending signals to cerebrum via the thalamus to increase excitability, it carries sensory signals that affect awareness, proceses visual, auditory, and touch stimuli, it tunes out stimuli when sleeping, allows us to be aware of stimuli awake, and involved with voluntary movement, filters a lot of sensory stimuli to prevent over stimlation

Hypothalamus functions

controls various homeostatic functions such as body temperature, respiration, and heartbeat, directs hormone secretions of the pituitary

Projection tracts

convey impulses to lower parts of the CNS (thalamus, brain stem, or spinal cord) or vise versa.

Cerebellum functions

coordinates subconscious movements, contributes to muscle tone, posture, and balance

Sleep

corticle activity depressed cognitive functions activity continues in the brain stem.

Frequency

degree of neurons firing together (beta waves have higher frequency than delta waves) A thinking brain produces waves with higher frequency (beta)

The limbic system location

encircles the upper part of the brain stem and the corpus callosum is a ring of structures on the inner border of the cerebrum, the floor of the diencephalon, and brain stem.

Sensory Memory

form important association based on sensory input, lasts for seconds

Parietal lobe functions

general sensory functions, taste, body awareness, language

Basal ganglia functions

helps coordinate slow sustained movements, suppresses useless patterns of movements.

Brain regions involved in language

includes functions of reading writing speaking and understanding 1. Wernicke's area-interepreting written and oral language, in the categorical hemisphere of most 2.Brocca's area/motor speech area-receives axons from Wernicke area, regulates motor activities needed for speech, sends signals to primary motor cortex ( innervate muscles of cheeks, larynx, lips and tongue) 3.Angular gyrus- posterier to Wernicke area, processes words read into speakable form 4. region opposite Wernicke area in respresentational hemisphere-recognizes the emotional content of speech 5.Region opposite motor speech area in respresentational hemisphere- responsible for producing speech with emotion, lesion producing aprosodia, dull emotionless speech

Brain stem functions

includes midbrain, pons, and medulla; origin of many cranial nerves; reflex center for movements of eyeballs, head, and trunk; regulates heartbeat and breathing; plays a role in consciousness;transmits impulses between brain and spinal cord

Reticular activating system (RAS

is the sensory part of the reticular formation responsible for alerting the cerebrum to incoming sensory information.

Short-term memory

limited capacity (7 small pieces of information), brief duration (seconds to hours)

Insula lobe functions

memory, interpretation of taste, sensory input with visceral responses to control autonomic responses, assesses bodily state in accordance to emotions, mirror neurons

Right hemisphere tends to process

musical and artistic awareness, spatial and pattern perception, recognition of faces and emotional content of language;discrimination of different smells and generating mental images of sight, sound, touch and taste, visual tasks

Occipital lobe functions

processing visual information, storing visual memories (recognizing objects), visual association

Reticular formation location and definition

projects vertically through the core of the midbrain, pons and medulla, loosely organized core of gray matter

Amplitude

range for maximal to minimal amplitude (delta waves have higher amplitude than beta waves)

The cerebral cortex functions

receives sensory info, sends messages to move skeletal muscles, integrates incoming and outgoing nerve impulses, performs activities such as thinking, learning and remembering

Thalamus functions

relays most sensory info from the spinal cord and certain parts of the brain to the cerebral cortex, interprets certain sensory messages such as those of pain, temperature and pressure

Memory

requires higher-order mental functions. depends on complex interactions among brain regions -3 types

Reticular formation function

sensory component, termed reticular activating system (RAS). motor component communicates with spinal cord, regulates muscle tone, assist in autonomic motor functions (heart rate), connects hippocampus with other diencephalon limbic system

Temporal lobe functions

sensory experiences, memory of visual and auditory, hearing, smell, reading

Long-term memories stored

stored primarily in association areas in premotor cortex and cerebellum, memory of sounds stored in auditory association area

What are the various parts of the brain

the cerebral cortex (thin top layer of cerebrum), cerebrum (the cerebral lobes), basal ganglia, diencephalon (composed of the thalamus and hypothalamus), cerebellum, the corpus callosum, brain stem (midbrain, pons, medulla)

The limbic system functions

the emotional brain. primary role in emotions like pleasure, pain, affection, sex , fear, aggression anger, reward/punishment (goal-directed behavior) . Also, memory.

EEG-electroencephalograph

uses electrodes to detect post-synaptic potentials at the dendrites and determine levels of activity of the cerebral cortex-does not indicate the exact location where a signal originates or provide information about a signal neuron.

Awake state

various stage of awareness. uncoordinated firing of cortical neurons due to ascending signals in reticular formation results in low-amplitude high frequency waves -As awareness declines it will result in high-amplitude low frequency waves.

Frontal lobe functions

voluntary motor functions, concentration and verbal communication-speech, decision making planning and personality, conscious thought [Primary Motor Area]