Psychology Midterm 1

October 5 2023 Thursday

Nerves

Bundles of axons and the glial cells which support them.

Nervous System

Network of neurons through the body that convey electrochemical information throughout the body.

Two Parts to Nervous System:

Central Nervous System

Peripheral Nervous System

Central Nervous System

Brain and Spinal Cord

Commands skeletal and muscular systems for action

Complex perceptual, motor, emotional, and cognitive functions.

Spinal cord branches down from the brain: nerves that process sensory information and relay commands to the body.

Peripheral Nervous System

Connects central nervous system to the body’s organs and muscles.

Peripheral Nervous System Two Parts

Somatic Nervous System

Autonomic Nervous System

Somatic Nervous System

Convey information between voluntary muscles and central nervous system.

Conscious control

Perceive → think → coordinate behaviours

Autonomic Nervous System

Involuntary and automatic commands that control blood vessels, body organs, glands,

Not in conscious control,

Two Parts

Two Parts of Autonomic Nervous System

Sympathetic and Parasympathetic

Sympathetic Nervous System

Prepares body for action in challenging situations.

Parasympathetic Nervous System

Helps the body return to a normal resting state, coordination of functions such as sexual activity

Spinal Reflex

Simple pathways in the nervous system that rapidly generate muscle contractions.

Reflex Arcs

Neutral pathways that control reflex actions.

Can include sensory neurons, interneurons, motor neurons.

Can also be simple and with only sensory and motor neurons.

Quadriplegia/Tetraplegia

Loss of sensation and motor neuron control in limbs due to a spinal cord injury.

Lower Brain Levels

Simpler function

Higher Brain Levels

Complex function

Networks

Interacting interdependent regions that work together to support complex psychological functions.

Hindbrain

Continuous with spinal cord

Coordinates information coming into and out of the spinal cord.

Medulla, Reticular formation, cerebellum, and Pons

Medulla

Extension of spinal cord into skull, coordinaates heart rate, circulation, and respiration.

Reticular Formation

Regulates sleep, wakefulness, and levels of arousal.

Site of anesthetic activity

Cerebellum

Large structure of the hindbrain that controls fine motor skills

Proper sequence of movements for skilled behaviour (Bike ride, playing piano)

Learning via fine-tuning of behaviour

Pons

Relays information from the cerebellum to the rest of the brain.

Midbrain

Tectum

Tegmentum

Tectum

Orients an organism in the environment.

Input from eyes, ears, skin

Tegmentum

Involved in movement and arousal.

Helps orient an organism toward sensory stimuli.

Forebrain

Complex cognitive, emotional, sensory, motor functions

Forebrain Parts

Cerebral cortex

Subcortical Structures

Thalamus

Hypothalamus

Cerebral cortex

Outermost layer of the brain, visible to the naked eye, divided into two hemispheres.

Subcortical Structures

Areas of the forebrain housed under the cerebral cortex near the center of the brain.

Thalamus

Relays, filters information from the senses. Transmits info to the cerebral cortex.

Closes pathways of incoming sensations during sleep.

(Like a bus station)

Hypothalamus

Regulates body temperature, hungers thirst, sexual behaviour.

Optimal range for normal human functioning,

Part of the limbic system

Limbic System

Group of forebrain structures involved in motivation, emotion, learning, and memory.

Limbic System Includes:

Hippocampus, hypothalamus, and amygdala

Hippocampus

Creating new memories, integrating them into a network of knoledge → indefinite storage in the cerebral cortex.

Damage ~ inability to cement new memories for facts and events

memory of learned habitual routines or emotional reactions may remain

Amygdala

Role in many emotional processes, including formation of emotional memories.

Attached significance to previously neutral events associated with fear, punishment, reward.

In emotional situations, amygdala stimulates hippocampus to remember details of the situation.

Alzheimer’s Disease

Progressive brain disorder that gradually impairs memory and other cognitive functions.

Leading cause of death in older adults.

90 million cases worldwide by 2050

More common among women than men.

Alzheimer’s Disease Affect on Physical Brain

Volume of hippocampus is reduced in AD

Volume decline is larger in women

Progression of volume decline is 1.5x faster in women

Possibly a reliable early indicator of AD onset in women, especially

Major Divisions of the Brain

Basal Ganglia

Striatum

Basal Ganglia

Set of subcortical structures that directs intentional movements.

Input from cerebral cortex

Outputs to motor centers in brainstem

Striatum

Caudate, putamen, ventral striatum

Controls posture and movement

Parkinson’s: midbrain supply dopamine to striatum is damaged causes tremor

Endocrine System

Network of glands that produce and secrete into the bloodstream chemicals known as hormones.

Thyroid

Regulates bodily functions like temperature and heart rate.

Adrennals

Regulate stress response

Pancreas

Controls digestion

Pineal

Secretes melatonin

Pituitary Gland

Master gland of body’s hormone-producing system, releases hormones that direct the functions of other glands in the body.

Receives hormonal signals from the hypothalamus.

Ovaries

Female sexual reproductive glands, making estrogen.

Testes

Male sexual reproductive glands, making testosterone.

Cerebral Cortex Texture

Gyri

Sulci

Gyri

Smooth raised surfaces, singular gyrus.

Sulci

Indentations, singular sulcus.

The Cerebral Cortex Across Hemispheres

Contralateral control

Commissures

Corpus callosum

Contralateral control

Left and right hemispheres control the functions of the opposite side of the body.

i.e. right hemisphere percieves left side stimuli…

Comissures

Connect left and right hemisphere, bundles of axons that communicate between each hemisphere.

Corpus Callosum

Connects large areas of the cerebral cortex between the hemispheres.

Cerebral Cortex Within Hemispheres

Occipital Lobe

Parietal Lobe

Occipital Lobe

Processes visual information

Parietal Lobe

Processes information about touch

Somatosensory cortex is strip of brain tissue on the front of the parietal lobe and represents contralateral surface body.

Homunculus

Somatosensory cortex can be illustrated as homunculus: body parts rendered according to how much of the somatosensory cortex is devoted to them.

Motor Cortex

Initiation of voluntary movements

Temporal Lobe

Responsible for hearing and language.

Primary auditory cortex

Primary auditory cortex

Receives information from the ears based on sound frequency…..

Frontal Lobe

Specialized areas for movement, abstract thinking, planning, memory, judgement.

Contains motor cortex.

Manipulate information, retrieve memories, plan behaviours, interact socially…

Association Areas

Composed of neurons that help provide sense and meaning to information in the cortex.

Mirror Neurons

Active when an animal performs a behaviour or observing the same behaviour

Plasticity

Small changes can happen in the nervous system.

Phantom Limb Syndrom

Amputees experience sensations where the missing limb would be.

The Influence of Practise

Musicians ~ more plasticity in motor cortex than non-musicians → increased number of motor synapses

Taxi drivers, overdeveloped hippocampi ~ spatial navigation

Exercise maximizes plasticity, increases # neurons in hippocampus

Invertebrates

Animals without a spinal column.

Evolutionary split in brain development.

Vertebrates

Animals with a spinal column

Evolutionary split in brain development

Chronic Traumatic Encephalopathy (CTE)

Progressive brain damage like repeated concussions lead to reduced brain size.

Cognitive and emotional deficits.

Memory loss, depression, etc.

Neuron

Cell in the nervous system.

Communicates with others for information-processing.

Santiago Ramon y CAJAL (1852-1934)

Golgi staining technique

highlighted entire cells

Does not stain every cell

Neuronal contact → neurons do not touch

Three Basic Parts to a Neuron

• Cell body/soma,

• Dendrites

• Axon

• Myelin Sheath

• Demyelinating diseases

• Synapse

Cell Body/Soma

Largest component of neurons, coordinates information-processing tasks, keeps the cell alive.

Protein Synthesis, energy production, metabolism.

Contains Nucleus (DNA)

Enclosed by porous cell membranes

Dendrites

Receive information from other neurons and relay it to the cell body.

Axon

Carries information to other neurons, muscles, or glands.

Myelin Sheath

Insulating layer of fatty material that covers many neurons.

Made of glial cells which are found in the nervous system.

Digest parts of dead neurons, provide physical and nutritional support.

Demyelinating Diseases

Multiple sclerosis → myelin sheaths deteriorate then neural communication slows down, loss of feeling in limbs, partial blindness, deficiencies in movement, cognition.

Synapse

Junction or region between the axon of one neuron and the dendrites or cell body of another.

Three Major Types of Neurons

Sensory neurons

Motor neurons

Interneurons

Sensory Neuron

Receive information from external world, convey this info to the brain (via spinal cord). Special ending on the dendrites allows for touch, smell, taste, sound, light…

Motor Neuron

Carry signals from spinal cord to muscles → movement

Interneurons

Connect sensory neurons, motor neurons, other interneurons.

Most neurons are interneurons.

Neuron Specialized Tasks

Purkinje cells

Pyramidal cells

Bipolar cells

Purkinje cells

Interneuron carrying information from cerebellum to the rest of the brain and spinal cord.

Dense and elaborate dendrites like a tree.

Pyramidal cells

Cerebral cortex, triangular cell body, single long dendrite and many smaller dendrites.

Bipolar cells

Sensory interneuron in retina, long dendrite and long axon.

How does information in the nervous system travel?

Electrochemically

How are electrical signals conducted?

They are conducted down axons to their terminal ends.

Chemical signals are __________ from one neuron to another across a __________.

Transmitted … synapse

Why is neuron cell membrane permeable?

To allow ions in and out of the cell

The permeability is the basis for conduction of an electrical signal.

Resting Potential

Electric charge at rest

Discovered in squid first

~ -70 millivolts

Inside Membrane: Resting Potential

High concentration of k+

Larger negatively charged proteins A-

Outside Membrane: Resting Potential

High concentration of Na+, Cl-

Why no concentration gradient?

Active pumps maintain high concentrations of k+ inside and Na+ outside creating potential energy.

Some K+ and Na+ channels are voltage-gated.

Action Potential

An electric signal conducted along the length of a neuron’s axon to a synapse.

When do APs (action potentials) Happen?

Action potentials only occur when stimulation reaches threshold.

What happens at the peak of Action Potential?

Na+ voltage-gated channels open.

Refractory Period

The time following an action potential when a new action potential cannot be initiated.

Limits the number of APs possible in a sequence.