Neuroscience: Reticular Formation and Cerebellum

Reticular Formation (RF)

• RF helps ignore constant information and become alert to changes.
• RF keeps people alert and aroused.
• The reticular activating system (RAS) stimulates the upper brain, keeping people awake and alert.
• RAS brings drivers to full attention when a sudden change occurs.
• RAS allows people to focus on important stimuli.

Cerebellum

• Located at the base of the skull, resembling a small brain.
• Controls involuntary, fine motor movements like posture and balance.
• Coordinates rapid, successive movements like walking, dancing, and speaking.
• People don't consciously think about posture, muscle tone, and balance due to the cerebellum.
• Spinocerebellar degeneration affects the cerebellum, leading to tremors, unsteady walking, slurred speech, and muscle weakness.
• The cerebellum is critical for certain types of learning and memory.
• Research suggests the cerebellum is involved in higher functions beyond motor control, including sensorimotor, cognitive, and emotional tasks.

Hypothalamus

• Regulates body temperature, eating, thirst, hunger, sleeping, waking, sexual activity, and emotions..
• Located above the pituitary gland.
• Controls the pituitary gland, ultimately regulating hormones in the body.

Hippocampus

• Located within the medial temporal lobe.
• Involved in forming long-term, permanent declarative memories.
• Contains acetylcholine, a neurotransmitter crucial for memory function.

Amygdala

• Located near the hippocampus.
• Involved in fear responses and memory of fear.
• Sensory information reaches the amygdala before the upper brain, allowing for quick responses to danger.
• Removal of the amygdala in monkeys and rats leads to a lack of fear response.
• Damage to the amygdala in humans can lead to decreased fear response.

Cingulate Cortex

• Located above the corpus callosum.
• Plays a role in emotional and cognitive processing of autonomic information.
• Active during cognitive tasks like selective attention, written word recognition, and working memory.
• Implicated in disorders like ADHD, schizophrenia, depression, and bipolar disorder.

Frontal Lobe

• Located at the front of the brain.
• Responsible for complex cognitive functions, problem-solving, planning, judgement, and decision-making.
• The visual association cortex interprets visual information, making sense of what we see.

Temporal Lobe

• Located behind the temples.
• Processes auditory information, including pitch, frequency, and sounds.
• Contains the primary auditory cortex and auditory association area.
• Involved in memory encoding, language comprehension, and emotional responses.
• Wernicke's Area in the left temporal lobe is crucial for language understanding.
• Damage to Wernicke's Area can lead to difficulty understanding the meaning of words, despite fluent speech.

Peripheral Nervous System (PNS)

• Connects the brain and spinal cord to the rest of the body.
• Contains all nerves and neurons outside the brain and spinal cord.
• Divided into the somatic and autonomic nervous systems.

Somatic Nervous System

• Responsible for voluntary control of skeletal muscles.
• Contains sensory neurons (afferent), carrying messages from sense organs to the CNS.
• Contains motor neurons (efferent), carrying messages from the CNS to muscles.
• Controls voluntary movements.

Autonomic Nervous System

• Controls involuntary organs, glands, and muscles.
• Divided into the sympathetic and parasympathetic divisions.

Sympathetic Division

• Located in the middle of the spinal column.
• Prepares the body for "fight or flight" responses during stressful situations..
• Increases heart rate, breathing, pupil dilation, and adrenaline release.
• Decreases digestive activity and blood flow to non-essential organs.

Parasympathetic Division

• Located at the top and bottom of the spinal column.
• Returns the body to a normal state after a stressful event ("eat-drink-and-rest").
• Slows heart rate and breathing, constricts pupils, reactivates digestion and excretion.
• Signals adrenal glands to stop stress hormone production.
• Responsible for day-to-day bodily functions.

Spinal Cord

• A long, thin tubular structure made up of neurons.
• Extends from the medulla oblongata to the lumbar region of the vertebral column.
• Contains the central canal filled with cerebrospinal fluid.
• Divided into a white matter (axons of neurons) and gray matter (cell bodies of neurons).
• Carries messages from the body to the brain.
• Carries messages from the brain to the body.
• The gray matter acts as a primitive brain.
• The gray matter is responsible for quick reflexes.

Reflex Arc

• An automatic, unconscious response to a stimulus.
• Consists of three neurons: sensory (afferent), interneurons, and motor (efferent).
• Sensory neurons carry messages from senses to the spinal cord.
• Interneurons connect sensory and motor neurons within the spinal cord and brain.
• Motor neurons carry messages from the spinal cord to muscles.

Neurotransmitters

• Chemicals released from synaptic vesicles at axon terminals.
• Activate the next neuron by attaching to dendrites of the postsynaptic neuron.
• A key link between the nervous system and behavior.
• Deficiencies or excesses can cause behavioral disorders.

Acetylcholine

• The first identified neurotransmitter.
• Excitatory.
• Common throughout the nervous system.
• Transmits messages to skeletal muscles, essential for movement.
• Blocked receptors can cause muscle paralysis.

Norepinephrine

• Excitatory.
• Important for arousal, alertness, and mood regulation.
• Contributes to sympathetic nervous system activation.
• Deficiencies can lead to depression and anxiety.

Dopamine

• Both excitatory and inhibitory.
• Associated with pleasure, reward, motivation, and movement control.
• Deficiencies can lead to Parkinson's disease.
• Excessive levels are linked to schizophrenia.