Unit 4: Biological Bases of Behavior in Psychology

Voltage threshold

Critical level of depolarization needed to initiate an action potential (~55 mV)

Neurotransmitters

Chemical messengers that transmit signals across the synaptic cleft

Receptor

channel in membrane of a neuron that binds neurotransmitters

Diffusion

neurotransmitter drift out of synapse

degradation

neurotransmitters are broken down in the synapse

reuptake

neurotransmitters are reabsorbed into the presynaptic terminal branches

Inhibition

receiving neuron slightly hyperpolarized; moves it further from threshold & reduces likelihood of action potential

GABA

Most common inhibitory neurotransmitter, involved in reducing stress and anxiety

Acetylcholine

Neurotransmitter triggering both excitatory and inhibitory signals, crucial in neuromuscular junction and autonomic nervous system; low levels associated with dementia of Alzheimer's disease

Norepinephrine

Neurotransmitter important for 'fight or flight' response, arousal, and vigilance

Serotonin

Neurotransmitter regulating sleep, appetite, mood, and aggression

Endorphins

Neurotransmitters promoting pleasure and reducing pain, binding to opioid receptors

Antagonist

Inhibits actions of a neurotransmitter by blocking release, destroying neurotransmitter in synapse, or mimicking neurotransmitter & binding to a postsynaptic receptor to block neurotransmitter

nervous system

complex network of nerves that controls and regulates all bodily functions

somatic nervous system

carries commands for voluntary movement from CNS to muscles; brings sensory input to CNS

sympathetic nervous system

prepares body for situations requiring expenditure of energy (fight-or-flight response); Redirects energy from non-essential processes

Parasympathetic nervous system

controls gland & organs during calm periods, returns body to resting state (rest-and-digest)

endocrine system

network of glands (hormone-secreting organs) that work together with CNS and PNS

pituitary gland

directs other glands; regulates hunger, sexual arousal, growth, sleep, navigation of social world

Prairie voles

typically from pair bonds after mating, exhibit biparental care

Montane voles

live in isolation, no evidence of pair bonding

Pons

Manages breathing, balance, relays sensory info to higher brain levels

Reticular Formation

Responsible for arousal, attention, and wakefulness

Hypothalamus

Regulates body functions, motivation, fight-or-flight response, directs autonomic and endocrine systems

Thalamus

Relay station for sensory signals (except smell); maintains alertness and consciousness

Hippocampus

Responsible for memory, spatial navigation, and mental time-travel

Basal Ganglia

Controls planning, executing voluntary movement, suppression of unwanted movement, and reward processing

2. Parietal Lobe

Primary somatosensory cortex (map of the body's skin surface); processes touch, attention, and spatial navigation

3. Occipital Lobe

Primary visual cortex; responsible for vision, interprets visual input, recognizes objects and movements

5. Insular Lobe

Perceives internal sensations, primary taste cortex, and loss of taste upon damage

Primary Sensory Areas

First cortical areas receiving signals from sensory nerves; include somatosensory, visual, auditory, olfactory, and taste areas

Association Cortex

Integrates sensory info with existing knowledge for meaningful experiences; facilitates multisensory integration

Organization of Primary Somatosensory & Motor Areas

Topographical organization mapping body parts to brain areas based on fine control and sensory discrimination needs

Corpus Callosum

Bridge of fibers connecting cerebral hemispheres for interhemispheric transfer

Contralateral Organization

Each hemisphere controls the opposite side of the body for sensory and motor functions

Split Brain Procedure

Severing corpus callosum to reduce seizures, revealing separate functions in each hemisphere

Interpreter

Concept suggesting left hemisphere interprets behavior and emotions in split-brain patients

Phrenology

19th-century belief mental traits are localized in specific brain regions; pattern od indentations on the skull

Non-human animal studies

Induce lesions in experimental animals using electric or chemical methods to observe behavioral effects

Deep Brain Stimulation (DBS)

Stimulating specific parts of the brain with implanted electrodes for treating disorders like depression

Transcranial Magnetic Stimulation (TMS)

Exposure to magnetic field to create temporary disruption or enhancement of cortical brain function

Functional Magnetic Resonance Imaging (FMRI)

Measures brain activity by detecting changes in blood oxygenation

Phantom limb syndrome

Continuing sensation in a limb that has been amputated due to cortical reorganization following amputation

critical periods

specific timeframe during development when brain is particularly receptive to environmental stimuli, allowing tor larger changes in neural connections

damage plasticity

neural modification/reorganization following injury

Neuron

Cell of the nervous system specialized for sending and receiving neural messages

Sensory neurons

Carry messages from sensory organs to spinal cord and brain

Motor neurons

Carry messages from brain and spinal cord to muscles and glands

Interneurons

Collect, integrate, & retrieve messages from various sources within the brain and spinal cord

Dendrites

Receives chemical messages from other neurons

Cell body/soma

Collects neural impulses, contains the nucleus, sustains cell functions

Axon

Transports electrical impulses to other neurons via terminal branches

Axon terminals/terminal branches

Convert electrical signals into chemical messages for other neurons

Myelin sheath

Fatty layer that insulates axons & speeds up transmission of electrical signals

Glia

Nervous system cells providing structural support, cleaning up debris, forming blood-brain barrier, facilitating neurons, and providing insulation

Action potential

Electrical impulses fired by neurons to communicate with each other; generated at the junction between the axon and cell body

Cell membrane

Thin fatty 'skin' enclosing the neuron, selectively permeable to certain ions

intracellular fluid

inside the neuron

extracellular fluid

outside the neuron

Resting potential

Electrical charge across the membrane (~70 millivolts) when neuron is not firing

ion channels

allow positively charged sodium ions (Na+) to enter

Depolarization

Reversal of electrical charge across the membrane as neuron is stimulated

Repolarization

Return of the electrical charge across the membrane to resting potential after depolarization

Propagation of the action potential

Movement of action potential along the axon, aided by myelination

Synaptic cleft

Gap separating neurons where chemical messages are transmitted

Excitation

receiving neuron slightly depolarized; moves it closer towarsds voltage threshold and increases likelihood of initiation of action potential

Types of neurotransmitters

Major classes include amino acids, GABA, acetylcholine, monoamines, neuropeptides, and endorphins

Dopamine

Neurotransmitter involved in movement, planning, reward, and addiction; excess levels - schizophrenia; low levels - Parkinson's disease

Psychoactive drugs

Chemical substances altering thoughts, feelings, or behaviors by influencing neurotransmitter activity in the nervous system

Agonist

Enhances action of a neurotransmitter by increasing release, blocking reuptake, or mimicking neurotransmitter & activating its postsynaptic receptor

Model of Opioid Addiction

Opioid drugs hijack & overpower reward function of endogenous opioids, leading to changes in receptor structure, tolerance to drug, and shift in locus of control for drug-seeking behavior

central nervous system

Brain, spinal cord

peripheral nervous system

nerves connecting brain to the rest of your body

Autonomic nervous system

carries involuntary commands to organs, blood vessels & glands

Hormone

blood-borne chemical messengers

adrenal hormones

SNS activities adrenal glands during stressful/threatening events-> release of adrenaline and cortisol

oxytocin

hormone released into bloodstream by pituitary gland; stimulates uterine contractions during birth; promotes lactation; thought to play role in social bonding

Spinal Cord

Major nerve bundle connecting brain to body; initiates spinal reflexes independently (without involvement of the brain)

Brainstem

Lowest brain region above spinal cord; regulates vital functions

Medulla

Controls heart rate, blood pressure, coughing, swallowing

Cerebellum

Coordinates balance, precise movements, and timing

Limbic System

Includes hypothalamus, thalamus, amygdala, hippocampus, basal ganglia; known as the 'emotional brain'

Amygdala

Processes emotional significance of sensory info, works with hippocampus for memory formation

Cerebral Cortex

Outer largest part of the brain; divided into left and right hemispheres and then 5 lobes; connected by corpus callosum

1. Frontal Lobe

Manages movement, primary motor cortex (map of the body's muscles); prefrontal cortex: executive functions, and emotional experiences

4. Temporal Lobe

Primary auditory and olfactory cortex; enables hearing, language comprehension, and object recognition

Symmetrical Brain

Most brain structures exist in duplicate; cerebral cortex divided into left and right hemispheres

Lateralization

Distinct functions located in either right or left hemisphere, e.g., language in left and nonverbal for the right

Broca's Area

Located in left frontal lobe; damage leads to telegraphic speech

Wernicke's Area

In temporal lobe; damage results in fluent but nonsensical speech

Neuropsychology

Study of brain function by examining functional alterations following brain damage

Lesion

Abnormal tissue resulting from disease, trauma, or surgical intervention

Single dissociation

Lesion to brain structure A disrupts function X but not function Y

Double dissociation

Lesion to brain structure A disrupts function X but not function Y, and lesion to brain structure B disrupts function Y but not function X

Naturally occurring brain damage

Not specifically localized & may spread over time

Transcranial Direct Current Stimulation (TDCS)

Low levels of direct current delivered via electrodes on the head to stimulate brain function

Positron Emission Tomography (PET)

Injection of radioactive tracer to study brain's use of specific neurochemicals

Single-cell recording

Measurement of the electrical activity of a single neuron

Electroencephalography (EEG)

Recording of electrical waves from many thousands of neurons in the brain using electrodes on the scalp

Event-Related Potentials

Synchronized electrical response to a sensory, cognitive, or motor event extracted from EEG data