Intro to Psych: Organization of the Neuron System and Structure of the Brain

Nervous System

the body’s fast communication system, consisting of billions of neurons, divided into the CNS and PNS

Central Nervous System (CNS)

the spinal cord and the brain

Function of the CNS

• handles the information processing tasks

• handles decision making tasks

Brain

the largest part of the CNS, consisting of about 80 billion neurons organized into neurons for processing sensory information, controlling behavior, and storing memories

Spinal Cord

the part of the nervous system that extends downward from the brain to the spine

What is the role of the spinal cord in reflexes?

to act as a processing center for rapid, involuntary responses without involving the brain

Peripheral Nervous System (PNS)

the sensory and motor neurons outside the brain and the spinal cord

• split into two parts the SNS and ANS

Function of the PNS

where sensory information from the outside world and from the inside of the body is channeled through

Somatic Nervous System

the part of PNS that carries sensory information and controls body movement

Function of the SNS

carries sensory information from skin and muscles and controls the body’s movement

Automatic Nervous System

the part of the PNS that regulates internal organs

• split into the SD and PD

Function of the ANS

communicates with and regulates internal organs, largely outside consciousness

Sympathetic Division

the part of the ANS that arouses the body for action

Function of the SD

arouses the body during emergencies, which prepares the body for an energetic physical response to a threat or challenge

Organs and SD Response

• Heart: speeds up heartbeat

• Eyes: dilates pupils

• Stomach: inhibits digestion

• Liver: increases glucose release

• Adrenal Gland & Kidney: releases stress hormones and slows kidney function

• Bladder: relaxes bladder

• Genitals: stimulates orgasm

Parasympathetic Divison

the part of the ANS that calms the body after a stressful event has passed

Function of the PD

relaxes the body during emergencies, also responsible for the localized sexual arousal of the genitals in males and females

Organ and PD Response

• Heart: slows heartbeat

• Eye: contracts pupils

• Liver: stimulates digestion

• Liver: increases bile release

• Bladder: contracts bladder

• Genitals: increases blood flow

Hindbrain Structure

the most primitive part of your brain, which coordinates information coming in and out the spinal cord and controls functions essential to life

• Medulla

• Reticular Formation

• Cerebellum

• Pons

Medulla (Hindbrain Structure)

an extension of the spinal cord that coordinates heart rate, circulation, and respiration

Reticular Formation (hindbrain structure)

regulates sleep, wakefulness, and levels of arousal

Cerebellum (Hindbrain Structure)

controls fine motor skills, plays a role in learning and remembering certain types of knowledge and skill

Pons (Hindbrain Structure)

relays information from the cerebellum and the rest of the brain

Midbrain Structure

a relatively small portion of your brain, which sits on top of the brainstem, responsible for visual and auditory orienting and regulating movement and arousal

• Tectum

• Tegmentum

Tectum (Midbrain Structure)

visual and orienting reflexes

Tegmentum (Midbrain Structure)

initiating movement and some aspects of arousal (ex. mental formation)

Subcortical Structures

the most recent evolutionary development, which is responsible for the CNS’s most complex functions

• Thalamus

• The Pituitary Gland

Thalamus (Subcortical Structure)

receives and transmits information from the senses to the cerebral cortex

The Pituitary Gland (Subcortical Structure)

the primary gland in the endocrine system, it receives signals from the hypothalamus and releases hormones that coordinate functions of other glands in the body

Limbic System

a group of forebrain structures

• Hypothalamus

• Amygdala

• Hippocampus

• Basal Ganglia

Hypothalamus (Limbic Structure)

regulates body temperature and motivational urges (ex: hunger, thirst, sexual behavior, etc)

Amygdala (Limbic Structure)

structure at the tips of each side of the hippocampus that plays a central role in emotional processes

Hippocampus (Limbic Structure)

a structure that’s critical for creating and integrating new memories

Basal Ganglia (Limbic Structure)

a set of subcortical structures that direct intentional movements

The Cerebral Cortex

the most visible and iconic part of your brain

Parts of the Cerebral Cortex

Gray Matter: where neuron cell bodies are all arranged, the outer layer of the cortex

White Matter: the interior of the neuron, which contains axons that transmit information to other cortical areas

Brain Folds

as your brain grows, the outer layer grows so much that it doesn’t know where to go, so it folds (seen as an evolutionary advantage)

Why are brain folds seen as an evolutionary advantage?

We are able to maximize the number of processing units, while minimizing the distance the signals have to travel between them

Right Cerebral Hemisphere

receives sensory information from and controls the movements of the left side of your body

Left Cerebral Hemisphere

perceives sensory information and controls the movements of the right side of your body

Contralateral Control

refers to the fact that each hemisphere manages the functions of the opposite side of the body

Commissures

bundles of axons that connect the two hemispheres, which makes communication possible between parallel areas of the cortex in each half

Corpus Callosum

the largest of commissures, which connects the large areas of the cerebral cortex on each side of the brain, and supports communication of information across hemispheres

Frontal Lobe

in the front of the cortex (behind the forehead)

• pre-frontal cortex

• frontal association area

• primary motor cortex

• Broca’s area (the motor speech area)

Pre-frontal cortex

planning, decision-making, problem solving, and social awareness

Frontal Association Area

planning actions and movements, as well as abstract thoughts

Primary Motor Cortex

initiates and coordinates muscle groups throughout the body

Broca’s area (the motor speech area)

interacts with the temporal cortex, devising a plan for speaking and passing the plan along the motor cortex, which controls the movement of the mouth

Parietal Lobe

located above and in front of the occiptial lobe

• primary somatosensory (somatic sensory) cortex

• somatosensory association area

Primary somatosensory (somatic sensory) cortex

processes information about touch

Somatosensory association area

Occiptal Lobe

located at the back of the cortex

• primary visual cortex

• visual association area

Primary Visual cortex

processes visual information

Visual association area

plays a primary role in your ability to recognize faces, dogs, cats, etc

Temporal Lobe

located on the lower side of each hemisphere

• primary auditory cortex

• Wernicke’s area (the sensory speech area)

• Auditory association area

Primary auditory cortex

responsible for hearing and language

Wernicke’s area (sensory speech area)

controls the ability to understand the meaning of words

Auditory Association area

registers sound frequencies

Association areas

consist of extensive territories of gray matter that surround and overshadow the primary sensory areas

• they perform complex tasks such as analyzing a scene and recognizing what we see

Mirror Neurons

cells that are active when someone performs a behavior and when they observe someone else performing the same behavior

• previously known as “monkey see, monkey do”

Brain Plasticity

our sensory cortices ability to adapt to changes in sensory input

• refers to the fact that functions can be reassigned to other areas in the brain to accomodate for changing input

Phantom Limb Syndrome

amputees who continue to experience sensations where the missing limb would be