Neuroanatomy Flashcards
Homologous structure
Evidence of common heritage of different animals is still visible in shapes of body and brain (all animals emerged from a common evolutionary ancestor; structures tend to be highly similar)
Why do we involve non-human animals in research about the human nervous system?
Due to structural homology, animal brains can provide an approximate model of the human brain for hypotheses that cannot be directly tested on human participants
What are the two major divisions of the nervous system and what do they do?
Central nervous system - brain and spinal cord
Peripheral nervous system - somatic nervous system and autonomic nervous system
What does the somatic nervous system do?
- part of PNS
- interacts with external environment
- external sensory signals carried into CNS by afferent nerves
- motor signals carried from CNS to skeletal muscles by efferent nerves
What does the autonomic nervous system do?
- part of PNS
- regulates internal environment
- internal sensory signals (internal organs) carried into CNS by afferent nerves
- motor signals carried from CNS to internal organs by efferent nerves
- state of ANS is function of degree of balance between sympathetic and parasympathetic nervous systems
What does the sympathetic nervous system do?
- part of autonomic nervous system in PNS
- sympathetic efferent nerves mobilize energy resources in threatening situations
What does the parasympathetic nervous system do?
- part of autonomic nervous system in PNS
- parasympathetic efferent nerves act to conserve energy
Bilateral symmetry
left and right sides of bodies are mirror-opposite (regions don’t necessarily perform the same functions on each side)
Corpus callosum
tract of neurons connecting left and right hemispheres
Contralaterality
each side of body is mostly controlled by the opposite side of the brain
Telencephalon
- largest division of the brain
- contains cerebral cortex
Cerebral cortex
- outer layer of the cerebrum
Major brain divisions
- cerebrum (left and right hemispheres; frontal, temporal, parietal, and occipital lobes)
- cerebellum (little brain)
- brainstem (relay centre between spinal cord and brain)
Convoluted vs. lissencephalic
convoluted: increased surface area, volume remains small (fissures/sulci & gyri)
lissencephalic: smooth-brained (many mammals inc. rats)
Sulci
fissures/furrows in cortex
Gyri
ridges between fissures (sulci)
Longitudinal fissure
longest fissure in brain
Cerebral commisures
tracts connecting cerebral hemispheres; largest is corpus callosum (connects left and right hemispheres)
What lobes does the central fissure separate?
frontal lobe from parietal lobe
What lobes does the lateral fissure separate?
frontal and parietal lobes from the temporal lobe
Limbic system
- group of structures that work together; involved in behavioural and emotional responses and memory
- hippocampus (memory)
- amygdala (fear and fear-based learning)
- hypothalamus (keeps body in homeostasis by influencing ANS and managing hormones)
Occipital lobe - main function (1), organization, location
- vision
- retinotopic organization (objects are represented similarly in field of vision and location in cortex)
- lower back of cerebrum (inferior posterior)
Temporal lobe - main function (6), important areas (2), location
- hearing, learning, memory, emotion, language, face recognition
- Wernicke’s area (speech comprehension)
- fusiform face area (face recognition)
- lower cerebrum (dorsal medial), over cerebellum
Parietal lobe - main function (1), important area (1), organization, location
- bodily sensations (touch, temperature, pain, etc.)
- somatosensory cortex (processes proprioception and touch info)
- topographic organization (representation is adjacent to neighboring areas)
- upper back of brain (superior posterior)
Frontal lobe - main function (3), important areas (3), location
- movement, planning, organization
- prefrontal cortex (higher level cognitive functioning
- motor cortex (planned, coordinated movement)
- Broca’s area (language production)
- front of cerebrum (anterior)
Anterior
ante, before
towards front
syn: rostral (beak)
Posterior
post, after
towards back
syn: caudal (tail)
Dorsal
dorsum, back
up/atop
syn: superior
Ventral
venter, belly
down, below, on bottom
syn: inferior
Medial
medius, middle
towards midline
syn: nasal (nose)
Lateral
latus, side
away from midline
syn: temporal (temple)
Ipsilateral
ipsi, same
same side of body
Contralateral
contra, against/opposite to
opposite sides of body
Key subcortical systems (4)
- thalamus
- basal ganglia
- hippocampus
- amygdala
Key cortical systems (3)
- somatosensory cortex
- motor cortex
- association areas
Thalamus - main function, location, subdivision
- relay station (most information that proceeds to cerebral cortex passes through thalamus)
- just above brainstem, near centre of brain (in midbrain); one in each hemisphere
- 50ish nuclei with multiple functional specializations
Basal Ganglia - main function (2), location, structural features (4)
- intermediary between higher thoughts, sensations, and reflexes; facilitates movement
- base of brain (basal), in temporal lobes
- cluster of nerve cells (ganglia)
- striatum (caudate, putamen, and nucleus accumbens), globus pallidus, substantia nigra, subthalamic nucleus
Hippocampus - main function (2), location, subdivisions (4)
- navigation, memory (cognitive mapping - time and space)
- in hippocampal formation (temporal lobes)
- Cornu ammonis 1, CA2, CA3, CA4
Amygdala - main function (4), location
- fear and threat detection, processing positive stimuli, emotional memory consolidation, attention to emotionally relevant stimuli
- in temporal lobes, anterior to hippocampus
Somatosensory cortex - main function (1), organization, location
- somatic sensation processing (touch, proprioception/kinesthesia, nociception, temperature); information moves from receptor through thalamus to somatosensory cortex
- somatotopic organization (point-for-point correspondence)
- in postcentral gyrus (posterior to central sulcus)
Proprioception
sense of position of body in space
syn: kinesthesia
Nociception
sense of pain
Motor cortex - main function (1), location, subdivisions (3)
- voluntary movement
- frontal lobe, anterior to central sulcus
- primary motor cortex (homunculous; corticospinal tract and corticobulbar tract), supplementary motor cortex (nonprimary), premotor cortex (nonprimary)
Primary motor cortex - main function (1), location
- contains motor map (homunculus); movement signals are transported to either corticospinal or corticobulbar tract
- precentral gyrus (strip of cortex)
Corticospinal tract
carries body movement related signals from primary motor cortex to spinal cord
Corticobulbar tract
carries head, neck, and face movement related signals to brainstem
Nonprimary motor cortex regions (2)
- supplementary motor cortex
- premotor cortex
Supplementary motor cortex - main function (3)
- execution of sequences of movement
- attainment of motor skills
- selection of movements (based on incoming sensory info)
Premotor cortex - main function (2)
- contributes about 30% of neurons that enter corticospinal tract
- planning of movement
Association areas - main function (2), locations, example (1)
- associate simpler elements of cognition (allowing for more complex elements of cognition)
- allow sensory experience to be tuned by expectations, needs, etc. (without these cortices, reflexive responses only)
- regions of temporal and parietal lobes
- prefrontal cortex
Prefrontal cortex - main functions (2), subregions (5), location
- executive functions
- uses sensory info to plan responses & communicate with other areas to enact them
- allows neural responses to reflect significance rather than surface properties of sensory events
- orbitofrontal cortex; ventrolateral pfc; dorsolateral pfc; dorsomedial cortex; ventromedial cortex
Executive functions
- processes that focus on controlling short-sighted behaviour, to act with a goal in mind
- self control, planning, decision making, problem solving
Mesolimbic dopamine pathway
- activated in association with rewards
- dopamine neurons project from ventral tegmental area to nucleus accumbens in basal ganglia
Orbitofrontal cortex (OFC)
- region of PFC
- understand relationship between action and outcome
- damage - reasoning intact but application of reasoning to decisions isn’t
Ventrolateral PFC
- region of PFC
- inferior frontal gyrus (IFG): unhelpful action and thought inhibition
Dorsolateral PFC (DLPFC)
- working memory
- complex sets of rules; other abstract thought
Gray matter
brain cells
White matter
highways of axons
Different types of brain tissue (3)
Gray matter - brain cells
White matter - highways of axons
Cerebrospinal fluid - fluid in ventricles (cavities)
