MCAT Behavioral Sciences - Biology and Behavior

Franz Gall (1758–1828)

phrenology - theories that behaviour, intellect, and personality linked to brain anatomy; could be measured by feeling skull; pseudoscience; impetus for the work of other psychologists

Pierre Flourens (1794–1867)

study’s sections of the brain through extirpation on rabbits and pigeons; work led to his assertion that specific parts of the brain had specific functions, and that the removal of one part weakens the whole brain

extirpation/ablation

various parts of the brain are surgically removed and the behavioral consequences are observed

William James (1842–1910)

founder of American psychology, studied how mind adapts to environment

functionalism

school of psychology which studies how mental processes help individuals adapt to their environments

John Dewey (1859–1952)

inception of functionalism, Dewey believed that psychology should focus on the study of the organism as a whole as it functioned to adapt to the environment; criticized the concept of the reflex arc, which breaks the process of reacting to a stimulus into discrete parts

Paul Broca (1824–1880)

examined the behavioral deficits of people with brain damage, the first person to demonstrate that specific functional impairments could be linked with specific brain lesions, Broca’s area

Hermann von Helmholtz (1821–1894)

the first to measure the speed of a nerve impulse, related to reaction time; made psychology a quantifiable natural science

Sir Charles Sherrington (1857–1952)

inferred the existence of synapses; largely correct except synaptic connections are a chemical, not electrical process

nervous system

a complex web of over 100 billion cells that communicate, coordinate, and regulate signals for the rest of the body

Sensory/afferent neurons

transmit sensory information from receptors to the spinal cord and brain

Motor/efferent neurons

transmit motor information from the brain and spinal cord to muscles and glands

Interneurons

found between other neurons; the most numerous; predominantly in the brain and spinal cord; linked to refelxive behaviour

reflex arcs

neural circuits that control reflexive behaviours

central nervous system (CNS)

brain and spinal cord

peripheral nervous system (PNS)

nerve tissue and fibers outside the brain and spinal cord

spinal nerves

31 pairs of nerves emanating from the spinal cord

cranial nerves

12 pairs of nerves emanating directly from the brain

olfactory and optic nerves

cranial nerves I and II; structurally outgrowths of CNS, but considered PNS

somatic nervous system

(PNS) sensory and motor neurons distributed throughout the skin, joints, and muscles

autonomic nervous system (ANS)

(PNS) regulates heartbeat, respiration, digestion, glandular secretions and other involuntary muscles; also helps regulate body temperature by activating sweating or piloerection

parasympathetic nervous system

conserve energy; rest-and-digest; acts to reduce heart rate, constrict the bronchi, increasing peristalsis, exocrine secretions

Acetylcholine

neurotransmitter responsible for parasympathetic responses in the body

sympathetic nervous system

activated by stress; fight-or-flight; Increases heart rate, Redistributes blood to muscles of locomotion, Increases blood glucose concentration, Relaxes the bronchi, Decreases digestion and peristalsis, Dilates the eyes to maximize light intake, Releases epinephrine into the bloodstream

meninges

a thick, three-layered sheath of connective tissue around the brain

dura mater

outermost layer of meninges; connected directly to the skull

arachnoid mater

middle layer of meninges; fibrous, web-like structure

pia mater

innermost layer of meninges; connected directly to the brain

cerebrospinal fluid

is the aqueous solution that nourishes the brain and spinal cord; provides a protective cushion; produced by specialized cells that line the ventricles of the brain

ventricles

internal cavities of the brain

brainstem

hindbrain and midbrain; evolved first and most primitive

limbic system

a group of neural structures primarily associated with emotion and memory; include the septal nuclei, amygdala, hippocampus, and anterior cingulate cortex.

cerebral cortex/neocortex

the outer covering of the cerebral hemispheres; associated with complex perceptual, cognitive, and behavioral processes: everything from language processing to problem solving, and from impulse control to long-term planning

divided into four lobes: frontal, parietal, temporal, occipital

Forebrain

most “modern” portion of the brain; forms the largest portion of the brain by weight and volume

includes cerebral cortex, basal ganglia, limbic system, thalamus, hypothalamus

basal ganglia

coordinate muscle movement as they receive information from the cortex and relay this information to the brain and the spinal cord; may also play a role in schizophrenia and obsessive–compulsive disorder

Thalamus

sensory relay station for all senses except smell

hypothalamus

homeostatic functions (metabolism, temperature, water balance, hunger, thirst), emotional experiences during high arousal states, aggressive behavior, and sexual behavior; links endocrine functions and (autonomic) nervous system; regulates the hormonal function of pituatary

subdivided into the lateral, ventromedial, and anterior

Midbrain

sensorimotor information and reflexes; includes inferior and superior colliculi

Hindbrain

manages vital functioning necessary for survival

includes cerebellum, medulla oblongata, reticular formation, pons

Cerebellum

refined motor movements, maintain posture and balance and coordinates body movements

impaired by alcohol; damage causes clumsiness, slurred speech, and loss of balance

Medulla oblongata

lower brain structure; breathing, heart rate, digestion, vital reflexes (reflexes, coughing)

Reticular formation

arousal and alertness

Pons

above medulla; contains sensory and motor pathways between the cortex and the medulla, breathing

prenatal development

three swellings → five swellings

rhombencephalon

embryonic hindbrain; divides into myelencephalon and metencephalon

myelencephalon

becomes the medulla oblongata

metencephalon

becomes the pons and cerebellum

mesencephalon

prenatal midbrain

colliculi

prominent nuclei in the midbrain

superior colliculus

receives visual sensory input

inferior colliculus

sensory information from the auditory system; reflexive reactions to sudden loud noises

prosencephalon

prenatal forebrain; divides into telencephalon and diencephalon

telencephalon

forms the cerebral cortex, basal ganglia, and limbic system

diencephalon

forms the thalamus, hypothalamus, posterior pituitary gland, and pineal gland

Neuropsychology

the study of functions and behaviors associated with specific regions of the brain; studied with brain lesions (human/animal), electrical stimulation,

cortical maps

collections (areas) of minicolumns in the brain cortex that have been identified as performing a specific information processing function

electroencephalogram (EEG)

placing several electrodes on the scalp to observe electrical activity generated by larger groups of neurons

regional cerebral blood flow (rCBF)

detects broad patterns of neural activity based on increased blood flow to different parts of the brain; the patient inhales a harmless radioactive gas; a special device that can detect radioactivity in the bloodstream can then correlate radioactivity levels with regional cerebral blood flow.

CT (computed tomography)/CAT (computed axial tomography) scan

multiple X-rays are taken at different angles and processed by a computer to produce cross-sectional images of the tissue

PET (positron emission tomography) scan

a radioactive sugar is injected and absorbed into the body, and its dispersion and uptake throughout the target tissue is imaged

MRI (magnetic resonance imaging)

a magnetic field that interacts with hydrogen atoms is used to map out hydrogen dense regions of the body

fMRI (functional magnetic resonance imaging)

same base technique as MRI, but specifically measures changes associated with blood flow

lateral hypothalamus (LH)

the hunger center; has special receptors thought to detect when the body needs more food or fluids; damage can lead to starvation

ventromedial hypothalamus (VMH)

the “satiety center”; provides signals to stop eating; damage can lead to obesity

anterior hypothalamus

controls sexual behavior; activation leads to hypersexuality, damage leads to hyposexuality

posterior pituitary gland

comprised of axonal projections from the hypothalamus; releases ADH/vasopressin and oxytocin

pineal gland

secretes melatonin to regulate circadian rhythms; receives direct signals from the retina for coordination with sunlight

extrapyramidal system

gathers information about body position and carries this information to the central nervous system, but does not function directly through motor neurons

Parkinson’s disease

chronic illness associated with destruction of portions of the basal ganglia; characterized by jerky movements and uncontrolled resting tremors

septal nuclei

one of the primary pleasure centers in the brain; associated with addictive behaviour

amygdala

defensive and aggressive behaviors, including fear and rage; ;esions result in docility, hypersexuality, and hyperorality

hippocampus

consolidate information to form long-term memories, and can redistribute remote memories to the cerebral cortex

fornix

projection of the hippocampus through which the hippocampus communicates with the limbic system

anterograde amnesia

characterised by not being able to establish new long-term memories, whereas memory for events that occurred before brain injury is usually intact

retrograde amnesia

memory loss of events that transpired before brain injury

anterior cingulate cortex

higher order cognitive processes, including regulation of impulse control and decision-making

gyri

bumps in the cerebral cortex

sulci

folds in the cerebral cortex

frontal lobe

anterior of the cerebral cortex

comprised of the prefrontal cortex and motor cortex

prefrontal cortex

manages executive function by supervising and directing the operations of other brain regions; supervises processes associated with perception, memory, emotion, impulse control, and long-term planning

damage impairs supervisory functions, increases impulsivity,

association area

an area that integrates input from diverse regions of the brain

projection areas

perform more rudimentary perceptual and motor tasks

primary motor cortex

initiate voluntary motor movements by sending neural impulses down the spinal cord towards the muscles

precentral gyrus

location of the primary motor cortex

central sulcus

fold that divides the frontal and parietal lobes

motor homunculus

systematic representaion of motor cortex neurons according to the parts of the body to which they are connected; Because certain sets of muscles require finer motor control than others, they take up additional space in the cortex relative to their size in the body

Broca’s area

vitally important for speech production; only present in ‘dominant’ hemisphere

Parietal lobe

superior of cerebral cortex; posterior to frontal lobe; associated with spatial processing and manipulation, makes it possible to orient oneself and other objects in three-dimensional space, to do spatial manipulation of objects, and to apply spatial orientation skills such as those required for map reading

somatosensory cortex

involved in somatosensory information processing; destination for all incoming sensory signals for touch, pressure, temperature, and pain

sensorimotor cortex

combination of somatosensory cortex of the parietal lobe and motor cortex of the frontal lobe

postcentral gyrus

location of somatosensory cortex

somatosensory homunculus

systematic representaion of somatosensory cortex neurons according to the parts of the body to which they are connected; Because certain body parts are more sensitive than others, they take up additional space in the cortex relative to their size in the body

occipital lobe

posterior of the cerebral cortex; contains visual cortex

visual/striate cortex

one of the best-understood brain regions; appeared striped under microscope; associated with vision; implicated in learning and motor control

speech shadowing

involves participants reciting along with auditory inputs, which can be presented to one or both ears; requires successful functioning of temporal lobe, parietal lobe, and frontal cortex

temporal lobes

lateral of the cerebral cortex; contains auditory cortex and Wernicke’s area; also functions in memory processing (hippocampus is deep), emotion, and language

auditory cortex

primary site of most sound processing, including speech, music, and other sound information

Wernicke’s area

associated with language reception and comprehension; only present in ‘dominant’ hemisphere