Cog Neuro Exam 1

Top-down Processing

A cognitive process where higher-level functions guide perception and interpretation of sensory information, influenced by expectations and prior knowledge

Bottom-up Processing

Perception is built from the smallest pieces of sensory information without the influence of prior knowledge or expectations.

Transcranial Magnetic Stimulation (TMS) Characterization

Has poor spatial and temporal resolution but is useful for understanding causal relationships in brain function. It creates a temporary virtual lesion, which is semi-invasive.

Electroencephalography (EEG) Characterization

Has excellent temporal resolution, poor spatial resolution, and is non-invasive.

Magnetoencephalography (MEG) Characterization

Has excellent temporal resolution, good spatial resolution, and is non-invasive. Similar to EEG but with better spatial resolution. Great for very shallow, surface level brain areas

Computerized Axial Tomography (CAT) Characterization

Has low spatial resolution, poor tissue contrast, and emits radiation. However, it’s fast, safe, and cheap.

Positron Emission Tomography (PET) Characterization

Has poor spatial and temporal resolution, is somewhat invasive, but gives unique data.

Magnetic Resonance Imaging (MRI) Characterization

Has excellent spatial resolution, decent temporal resolution, and is non-invasive. However, the magnet can be dangerous.

Functional MRI (fMRI) Characterization

Has excellent spatial resolution, decent temporal resolution, and is non-invasive. However, the magnet can be dangerous.

Cellular Recording Characterization

Excellent spatial and temporal resolution, but incredibly invasive

Superior or Dorsal

Top of brain

Inferior or Ventral

Bottom of brain

Anterior or Rostral

Front of brain

Posterior or Caudal

Back of brain

Medial

Towards middle of brain

Lateral

Towards side of brain

Sagittal Slice

Divides brain into left and right

Axial Slice

Divides brain into top and bottom (superior and inferior)

Coronal Slice

Divides brain into front and back (anterior and posterior)

Ipsilateral

On the same side

Contralateral

On the opposite side

Proximal

Toward the point where limb attaches to the body

Distal

Toward the end of the limb

Gray Matter

Tissue that contains unmyelinated cell bodies and dendrites on the outer layer of the brain, responsible for thinking and decision making.

White Matter

Tissue that contains myelinated axons and nerve fibers in deeper parts of the brain, responsible for carrying infromation over long distances.

Forebrain (Prosencephalon)

Divided into telencephalon and diencephalon

Telencephalon

Cerebral hemispheres: cerebral cortex, subcortical white matter, basal ganglia, and basal forebrain nuclei

Diencephalon

Thalamus and hypothalamus

Midbrain (mesencephalon)

Surivival-related conscious behaviors - periaqueductal gray, reticular formation, locus coeruleus, and substantia nigra

Hindbrain (rhombencephalon)

Divided into metencephalon and myelencephalon

Metencephalon

Pons and cerebellum

Myelencephalon

Medulla

Peripheral Nervous System

Connects spinal cord to the rest of the body, composed of somatic (outer) and autonomic (inner) nervous system.

Somatic Nervous System

Directs and processes information from external stimuli and uses it to guide the body’s movements - somatosensory inputs and motor outputs.

Autonomic Nervous System

Directs activity of internal (visceral) organs in response to signals from the internal environment - visceral inputs, sympathatic & parasympathetic outputs.

Sympathetic Nervous System

Fight or flight response - quickened heartbeat, increased respiration and blood pressure, slowed digestive tract, and circulation shift from digestive organs to muscles.

Parasympathetic Nervous System

Rest and regenerate response - slowed heart rate, decreased respiration and blood pressure, relaxed muscle tone, and blood flow shift to stomach and digestive organs.

Sensory Input

Enters spinal cord through dorsal nerve root at the back of the spinal cord

Motor Output

Exits spinal cord through ventral nerve root at the front of the spinal cord

Sensory Neurons

Collect information from inside and outside the body

Motor Neurons

Carry signals to muscles for movement.

Central Nervous System

Brain and spinal cord - central pattern generators in the spinal cord contain a combination of excitatory and inhibitory neurons that balance together to form simple movements

Cerebrum

Seperated into left and right hemispheres, initiates and coordinates movement, regulates temperature, handles thinking, speech, memory, learning, judgement, and senses. Divided into four lobes.

Frontal Lobe

High-order cognitive processsing, decision-making, control of voluntary movement, and perception of sensory stimuli. Contains Broca’s area - key role in speech.

Parietal Lobe

Processes sensory information like pain and touch, helps people understand spacial relationships and identify objects. Contains Wernicke’s area - key role in understanding spoken language.

Temporal Lobe

Auditory processing, memory formation, speech, musical rhythm, hearing, and vision.

Occipital Lobe

Visual processing - color perception, visualspatial processing, facial recogntition, and memory formation.

Cerebellum

Responsible for highly coordinated, fine-tuned movements, predicts outcome of motor actions, in addition to language, memory, attention, and emotion. Comprised of neurons and cerebral cortex.

Lateral Cotricospinal Tract

80% of corticospinal axons cross over at the medulla and form this pathway, 10% cross over when exiting the spinal cord, and the rest remain on the same side

Brainstem

Involuntary and automatic functions - composed of midbrain, medulla oblongata, and pons

Medulla Oblongata

Responsible for involuntary functions like breathing and heart rate, as well as reflexive activities like coughing and swallowing

Pons

Responsible for cerebellum-cortex relay, sleep, arousal, and sensory information

Periaqueductal Gray

Cluster of nerve cells that manage pain relief; fight, flight, or freeze responses; and basic bodily functions

Reticular Formation

Responsible for consciousness

Locus Coeruleus

Responsible for alertness and arousal

Substantia Nigra

Responsible for motor control and reward learning

Hypothalamus

Regulates autonomic responses and behaviors, releases hormones via pituitary gland

Thalamus

Relays sensory signals to cerebral cortex, conveys brain and motor signals to the body

Cerebral Cortex

Outer layer of the brain, responsible for reasoning, emotion, thought, memory, language, and consciousness

Basal Ganglia

Initiating and maintaining activity, especially in the motor cortex, also involved in habit and reward processing. Contains striatum (caudate nucleus and putamen), and globus pallidus

Straitum

Made up of caudate nucleus and putamen

Caudate Nucleus

Comet-shaped structure, motor and behavioral functions

Putamen

Sits within the “C” of the caudate, learning and motor control

Globus pallidus

Oval structure, regulates voluntary movement

Limbic System

Emotions, memory, and basic drives, shaped like a fist in the middle of the forebrain. Integrates internal and external representations. Mamillary bodies and fornix relay information between the hippocampus and other brain areas. Comprised of amygdala and hippocampus.

Amygdala

Emotional evaluation and learning, links external sensory inputs to emotional states

Hippocampus

Learning, memory, episodic memory, and spatial navigation

Fornix

C-shaped pathway of white matter connects the hippocampus to mamillary bodies and the thalamus

Mammillary Bodies

A pair of nuclei in the hypothalamus, helps with memory consolidation, spacial orientation, and connects hippocampus to anterior thalamic nucleus

Neuronal Anatomy

Soma, nucleus, dendrites, axon, axon terminals, and terminal branches

Soma

Integrates signals from dendrites and generates signal that travels down axon

Dendrites

Collects thousands of incoming signals

Axon

Conducts signals rapidly across long distances

Axon Terminals

Where messages are sent to a neighbor neuron

Synapse

Junction where axon terminals are in close proximity to the dendrites and somas of other cells

Resting Membrane Potential

The electrical charge difference across a cell’s plasma membrane when the cell is at rest. The inside of the cell is more negative than the inside (the cell is polarized).

Ion Channels

Allow ions to pass through a non-permeable cell membrane, generating resting membrane potential, action potentials, and synaptic responses.

Excitatory Postsynaptic Receptors (EPSPs)

Postive ions flow through a receptor into the cell, causing depolarization and increasing the chance of firing an action potential

Inhibitory Postsynaptic Potentials (IPSPs)

The binding of neurotransmitters makes the inside of the cell more negative from negative ions flowing into the cell or from positive ions flowing out of the cell, making it harder for the neuron to fire

Action Potential

Sudden change in electrical properties of a neuron’s membrane in an axon, composed of several phases, sodium and potassium play key roles.

Sodium Potassium Pump

Pumping sodium out and potassium into the cell creates a membrane potential

Postsynaptic Receptors

Receptors on the receiving end of a synapse that bind to neurotransmitters

Synaptic Cleft

Space between pre and post synaptic cells

Neurotransmitter Degradation

Enzymes come through and break down the neurotransmitter in the synaptic cleft

Neurotransmitter Diffusion

The neurotransmitter floats away from the synapses and gets lost

Neurotransmitter Reuptake

The neurotransmitter is taken back into the pre-synaptic cell to be recycled and released again

Polarized Cell

Greater concentration of positive ions outside the cell, the inside is negative relative to the outside

Depolarized Cell

Greater concentration of negative ions outside the cell, the inside is positive relative to the outside

Temporal Summation

Signals that arrive to the soma at the same time will add up once they reach the soma, leading to an action potential

Spatial Summation

Signals that arrive on different branches of the dendrites converge at the soma

EPSP + IPSP

If an EPSP and IPSP arrive at a different location at the same time, they will cancel each other’s effect at the soma

Action Potential Stages

Resting state, depolarization, action potential, repolarization, refractory period, return to resting state. Depolarization must hit a threshold to cause an action potential

Cell at Rest

High concentration of Na+ on the outside and lower on the inside; low concentration of K+ on the outside and higher on the inside

Voltage-Gated Ion Channels

Selectively pass Na+ and only open at particular voltages across the membrane, driven by concentration and electrical gradient. This depolarization triggers the opening of K+ channels, causing K+ to rush out the cell and repolarize the cell (inside becomes more negative).

Refractory Period

After an action potential, Na+ channels are more resistant to opening and need time to reopen, so the action potential can only travel forward towards the axon terminal

Glial cells

Non-neuronal cells that support, nourish, and protect neurons

Oligodendrocytes

Myelinate axons, called Schwann cells in the peripheral nervous system

Microglia

Immune responses, inflammatory responses, and debris removal

Ependymal Cells

Line ventricles

Astrocytes

Form blood-brain barrier, provide nutrients to neurons from blood, structural support, repair to central nervous system