Cognitive Neuroscience I

neurons

eukaryotic cells specialised for communication via chemical/electrical signals

glia

serve in a number of support roles vital for neurons

gyrus

bulge on the surface of the cerebral cortex

sulcus

depression on the surface of the cerebral cortex

ANS

autonomic nervous system, divided into sympathetic and parasympathetic divisions

McGurk effect

an error in perception that occurs when we misperceive sounds because the audio and visual parts of the speech are mismatched.

Brodmann areas

Areas of the human cerebral cortex that are distinct from each other anatomically and in cellular composition

MRI

magnetic resonance imaging, provides higher resolution

CT scan

very quick

white = high-density, black = low density

EEG

electroencephalogram

fMRI

a form of magnetic resonance imaging of the brain that registers blood flow to functioning areas of the brain

can be used to determine which part of the brain is responsible for what: if you compare brain activity between a strong visual stimulus and a weak one, you can determine which part is responsible for visual stimulation

Homunculus

a map-like representation of regions of the body distorted to the scale at which these areas are treated in the brain

bigger=more neurons

smaller=less neurons

basal ganglia

includes several brain structures, including the thalamus surrounded by the c-shaped structure (surrounded by the amygdalae)

limbic system function, structures, and why smell -> memory?

associated with emotional processing

hippocampus, amygdalae, cingulate gyrus, olfactory bulbs

smell leading to memories can be because olfactory bulb really close to hippocampus!

amygdala

both in the basal ganglia and limbic system

ventricles

shock absorption, nutrient exchange

Circle of Willis

A structure at the base of the brain that is formed by the joining of the carotid and basilar arteries.

blood vessels function

provide oxygen to the brain

brain haemorrhage

bleeding in the brain

basic building blocks of the nervous system

neurons and glia

3 types of neurons

unipolar, bipolar, multipolar

afferent neuron

Neuron that conducts impulses toward the CNS from the body periphery.

efferent neuron

Neuron that conducts impulses away from the CNS to muscles and glands.

interneurons

operate between sensory and motor neurons

soma

cell body of a neuron

dendritic spine

a small bud on the surface of a dendrite, with which a terminal button of another neuron forms a synapse

axon hillock

Cone shaped region of an axon where it joins the cell body.

3 types of glial cells

astrocytes, oligodendrocytes, microglia

astrocyte

star-shaped glial cell that maintains the BBB, filtering out chemicals and pathogens

BBB

blood brain barrier

microglia

Act as phagocytes, eating damaged cells and bacteria, act as the brains immune system

Oligodendrocytes

Type of glial cell in the CNS that wrap axons in a myelin sheath.

Schwann Cells

Type of glia in the PNS, Supporting cells of the peripheral nervous system responsible for the formation of myelin.

invertebrate nervous system

composed of simpler neural nets and sometimes nerve chords connected to ganglia in more complex invertebrates

Vertebrate Nervous System

centralised brain and CNS + PNS

bilateral symmetry

Body plan in which only a single, imaginary line can divide the body into two equal halves.

radial symmetry

The quality of having many lines of symmetry that all pass through a central point.

nervous system centralisation

nervous system organisation where neurons are not randomly arranged in the body, but in specific areas of integration

nuclei

clusters of neuron bodies in CNS

nerves vs. tracts

nerves: axons in PNS

tracts: axons in CNS

white vs gray matter

White - myelinated

Gray - unmyelinated

3 layers of the meninges

dura mater, arachnoid mater, pia mater

CSF

cerebrospinal fluid

4 ventricles

2 lateral ventricles

3rd ventricle

4th ventricle

3 main brain arteries

anterior, middle, posterior

neural circuits

signal-relaying network of interconnected neurons

CNS structure

made up of the brain and spinal cord, and in extension the retina

retina

Light sensitive layer of the eye; contains rods and cones

ipsilateral

same side

contralateral

opposite side

ectoderm

outer embryo tissue that forms the spinal chord, brain, nervous system, and skin

3 parts of the brain

forebrain, midbrain, hindbrain

forebrain

telencephalon and diencephalon

hindbrain

myelencephalon and metencephalon

telencephalon

cerebral hemispheres

diencephalon

thalamus and hypothalamus

Myelencephalon

medulla

mesencephalon

cerebellum and pons

5 regions of the spinal chord

cervical, thoracic, lumbar, sacral, coccygeal

dermatome

innervated area of skin

cerebral commisures

tracts that connect the left and right cerebral hemispheres

thalamus

Relay station for sensory information

ganglia

clusters of neuron bodies in PNS

adrenaline

neurotransmitter and hormone used in the sympathetic nervous system

acetylcholine

neurotransmitter used in the parasympathetic nervous system

Multiple Sclerosis (MS)

Autoimmune disease where individuals’ immune system attacks myelin sheath of nerve fibres, leading to communication problems and severe motor problems

connectome

comprehensive map of neuronal connection

graded potential

spreads passively from synapse to axon hillock and from axon end to terminals

action potential

propagate actively over the axon

ionotropic receptor

transmembrane molecules that can either open or close a channel that would allow smaller particles to travel in and out of the cell

metabotropic receptor

do not have a channel, instead linked to a G protein like with a GPCR, involving secondary messengers

autoreceptor

special type of protein receptor providing neurons with feedback on how much neurotransmitters they are releasing at their axon terminals

how are neurotransmitters made?

produced inside neurons, depending on them getting adequate supply of precursors from the blood

why are GABA and Glutamate the most prevalent neurotransmitters?

require less energy to create, only needing a single-step enzyme process

BBB downside

would prevent important nutrient uptake by neurons from blood, but there are specialised proteins overcoming this problem, allowing important precursors for neurotransmitters to be taken up

3 steps of action potential generation

1. neurotransmitter causes depolarisation

2. electronic conduction of graded potential (charge flows through the soma to the axon hillock

3. voltage-sensitive Na+ channels open at base of axon hillock: here is where the action potential starts

Which opens faster Na+ or Na+?

Na+

3 possible states for voltage-gated Na+ channels

1. closed, but able to open

2. open

3. closed, but temporarily unable to open

2 possible states for voltage-gated K+ channel

1. closed state

2. open state

undershoot

explained by the fact that there are more K+ channels open, allowing even more K+ to leave, resulting in a lower membrane potential than usual

how can na+ continue entering even if the membrane potential is = 0

because of chemical gradient being so strong (way more na+ outside than in) which overrides this, allowing it to enter until even +30mv

absolute refractory period

cannot receive an a.p., because the Na+ channel is in its ‘closed and temporarily unable to open’ state

relative refractory period

able, but unlikely to receive a new action potential, since membrane potential even lower than usualp

pufferfish poison

tetradoxin → inhibits na+ gated channels, meaning no a.p.s and eventual organ failure and suffocation

agonist

neurotransmitter enhancing activation

antagonist

neurotransmitter blocking or inhibiting activation

4 types of neurotransmitters

amines, amino acids, neuropeptides, and gases

4 major pathways

cholinergic, dopaminergic, serotonergic, and noradrenergic

cholinergic pathway

nicotinic receptors (ionotropic) → curare (antagonist) causing paralysis

muscarinic receptors (metabotropic) → atropine (antagonist) causing pupil dilation

dopaminergic pathway

responsible in movement, reward and motivation

divided into mesostriatal and mesolimbocortical pathways

mesostriatal pathway

part of the dopaminergic pathway

projects from the substantia nigra to the basal ganglia

involved in motor control and when affected can lead to Parkinson’s disease

mesolimbocortical pathway

part of the dopaminergic pathway

limbic system

associated with reward

what neurotransmitter is used in the cholinergic pathway

acetylcholine

what neurotransmitter is used in the dopaminergic pathway

dopamine

what neurotransmitter is used in the serotonergic pathway

serotonin

what neurotransmitter is used in the noradrenergic pathway

norepinephrine

serotonergic pathway

mostly metabotropic

involved in eating regulation and emotion/mood

noradrenergic pathway

mostly metabotropic

involved in arousal and alertness