Neuroscience - Lecture notes All PDF

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Summary

Central Nervous SystemThis is made up of the brain and spinal cord. The brain is protected by the skull. The spinal cord travels from the back of the brain, down the centre of the spine, stopping in the lower back. These are both kept within a protective membrane called the meninges. This controls o...

Description

Central Nervous System This is made up of the brain and spinal cord. The brain is protected by the skull. The spinal cord travels from the back of the brain, down the centre of the spine, stopping in the lower back. These are both kept within a protective membrane called the meninges. This controls our thoughts, movements, emotions, and desires. It also controls our breathing, heart rate, the release of some hormones, body temperature, and much more. The nerve axons of the central nervous system are much shorter than peripheral nervous system nerve axons. The central nervous system doesn’t have the ability to regenerate.

Cerebral Hemispheres These form the outer surface of the brain and are characterized by numerous grooves (sulci/fissures). They’re connected by a white matter tract (corpus callosum – a bundle of neuronal axons which allow the hemispheres to communicate). These can be divided into several lobes which are further divided into functional areas.

Temporal Lobe This is at the bottom of the brain above the brain stem and is important for processing sensory input and assigning it emotional meaning. It’s involved in laying down long-term memories and some aspects of language perception.

Primary Auditory Cortex This is in the middle-top of the temporal lobe and is the first relay station for auditory information.

Wernicke’s Area This is involved in language comprehension. When damaged, people are unable to understand language and can still speak with normal fluency, but their sentences may be meaningless.

Occipital Lobe This is at the back of the brain behind the parietal lobe and is the visual processing region of the brain, housing the visual cortex.

Primary Visual Cortex This is at the back of the brain and contains a map of visual information received from the outside world.

Parietal Lobe This is at the top of the brain behind the frontal lobe. It integrates sensory information. Touch stimulation from the skin is ultimately sent to the parietal lobe. It also plays a part in language processing.

Primary Somatosensory Cortex This is at the front of the parietal lobe and integrates sensory information. This contains a representation of the localization of the different regions of the body.

Frontal Lobe This is at the front of the brain and contains the majority of dopaminesensitive neurons. This is involved in attention, reward, short-term memory, motivation, and planning.

Primary Motor Cortex This is at the back of the frontal lobe and generates the nerve impulses that initiate movements.

Premotor Cortex This makes up the middle portion of the frontal lobe and is thought to be involved in planning movements.

Prefrontal Cortex This is located at the very front of the brain and is involved in making and achieving goals.

Broca’s Area This is involved in language processing. When damaged, people find it difficult to speak but can still understand speech. Stuttering is sometimes

associated with an underactive Broca’s area.

Brain Regions Basal Ganglia This is involved in the control of voluntary motor movements, procedural learning, and decisions about which motor activities to carry out.

Cerebellum This is located at the base of the brain below the cerebral cortex and behind the brainstem. It’s involved in precise motor control, language and attention. When this is damaged, the primary symptom is disrupted motor control (ataxia).

Diencephalon This receives sensory inputs from the body and distributes the information to the appropriate areas of the brain. It is important in the regulation of the autonomic and endocrine systems.

Corpus Callosum This is a broad band of nerve fibres that join the left and right hemispheres. It is the largest white matter structure in the brain and allows the two hemispheres to communicate.

Medulla Oblongata This is involved in involuntary functions, such as vomiting, breathing, sneezing, and maintaining the correct blood pressure.

Hypothalamus This is above the brain stem and secretes a number of neurohormones and influences body temperature control, thirst, and hunger.

Thalamus This is positioned in the centre of the brain. It receives sensory and motor input and relays it to the rest of the cerebral cortex. It’s involved in the regulation of consciousness, sleep, awareness, and alertness.

Amygdala This is within the temporal lobe, involved in decision-making, memory, and emotional responses, particularly negative emotions.

Brain Stem This is located at the base of the skull and is continuous with the spinal cord. It is comprised of the midbrain, pons, and medulla oblongata. These areas are involved in sensory-motor relays and regulating vital autonomic functions.

Cerebrum This contains the cerebral cortex (outer layer), and the subcortical structures (areas in the centre of the brain) and is divided into left and right hemispheres. The two hemispheres are connected by the corpus callosum.

Cerebral Cortex This makes up the outer layer (grey matter) of the brain and is involved in higher brain functions including reasoning, abstract thought, and language.

Cerebellum This is the structure under the occipital lobe, connected to the brainstem. It’s important for smooth, coordinated, and precise movements, and receives a lot of sensory input.

Spinal Cord This is a continuation of the brainstem and carries information between the brain and body. From the brainstem, 31 spinal nerves enter the cord. It connects with the nerves of the peripheral nervous system that run in from the skin, muscles, and joints. Motor commands from the brain travel from the spine to the muscles and sensory information travels from the sensory tissues toward the spinal cord and finally up to the brain. The circuits within the spine can also generate more complex movements such as walking. Even without input from the brain, the spinal nerves can coordinate all of the muscles necessary

to walk. For instance, if the brain of a cat is separated from its spine so that its brain has no contact with its body, it will start spontaneously walking when placed on a treadmill. The brain is only required to stop and start the process, or make changes if, for instance, an object appears in your path.

White and Grey Matter Grey matter tends to make up the outer layer of the brain and an inner area housing tracts of white matter. This consists of the cell bodies of neurons and is where processing occurs. White matter consists of axons of neurons and oligodendrocytes and is where signals are conducted from one area of the grey matter to another.

Central Glial Cells (Neuroglia) These are often called support cells for neurons. Without glial cells, developing nerves often lose their way and struggle to form functioning synapses. These are found in both the central and peripheral nervous systems, but each have different types.

Central Nervous System (CNS) Glial Cells Astrocytes These regulate the local environment by removing excess ions and recycling neurotransmitters.

Oligodendrocytes These are responsible for creating the myelin sheath which coats nerve cells, allowing them to send signals quickly and efficiently.

Ependymal Cells These line the spinal cord and the brain’s ventricles, create and secrete cerebrospinal fluid (CSF) and keep it circulating.

Radial Glia These act as scaffolding for new nerve cells during the creation of the embryo’s nervous system.

Cranial Nerves These are 12 pairs of nerves that arise directly from the brain and pass-through holes in the skull. They collect and send information between the brain and parts of the body. The olfactory and optic nerves arise from the forebrain and are considered part of the central nervous system.

Olfactory Nerves (Cranial Nerve I) These transmit information about odours from the upper section of the nasal cavity to the olfactory bulbs on the base of the brain.

Optic Nerves (Cranial Nerve II) These carry visual information from the retina to the primary visual nuclei. Each optic nerve consists of around 1.7 million nerve fibres.

Peripheral Nervous System (PNS) This is made up of nerves (12 cranial and 31 spinal), and ganglion (soma of neurons) that connect to voluntary skeletal muscles and sensory receptors. It contains afferent nerves which carry information to the central nervous system (spinal cord) and efferent fibres

which carry neural impulses away from the central nervous system. This is divided into 2 main subdivisions.

Somatic Nervous System This is the voluntary component which consists of nerves that connect the brain and spinal cord with muscles and sensory receptors in the skin.

Autonomic Nervous System This is the involuntary component which regulates certain body processes, such as blood pressure and the rate of breathing, and connect the stomach, heart, lungs, sex organs, bladder that work without conscious effort. It consists of nerves that connect the brain and spinal cord with muscles and sensory receptors in the skin. This is further divided into the sympathetic and parasympathetic nervous systems.

action, such as increasing the heart rate, increasing the release of sugar from the liver into the blood, and other activities generally considered as fightor-flight responses.

Parasympathetic Nervous System This activates tranquil functions such as stimulation the secretion of saliva or digestive enzymes into the stomach and small intestine.

Sympathetic Nervous System This is involved in the stimulation of activities that prepare the body for

Terminology Traverse Plane (Axial / Horizontal Plane) This divides the body horizontally into upper (superior) and lower (inferior)

Coronal Plane (Frontal Plane) sections.

This divides the body vertically into front (ventral/anterior) and back (dorsal/posterior) sections.

Sagittal Plane (Longitudinal Plane) This divides the body down the midline into left and right sections.

indicate damage in the corticospinal tract.

Basal Ganglia These are located deep within the cerebral hemispheres and play an important role in the initiation and control of movements, as well as some aspects of learning, behaviour of habits, and emotion.

Broca's Area This is involved in language expression. People with damage to this area experience difficulty speaking in complete sentences while language comprehension is unimpaired. This is called expressive aphasia.

Cerebellum The Latin word for "little brain". This is important for movement and receives a lot of sensory input.

Directional Terms -

Rostral: Towards the forehead (anterior). Caudal: Towards the neck / back (posterior). Dorsal: Towards the back. Ventral: Towards the front. Medial: Towards the midline / middle. Lateral: Towards to side.

Definitions Afferent This means it carries information toward the central nervous system.

Autonomic Nervous System This consists of two components: sympathetic and parasympathetic. This mediates physiological arousal.

Babinski Sign This is one of two reflex responses which occur when the sole of the foot is stroked with a blunt object. The normal response is the big toe flexing downwards. The abnormal response is the big toe flexing upwards, which can

Cerebrum This contains the cerebral cortex (the outer layer), and the subcortical structures (the areas in the centre of the brain).

Cognitive Functions These include abstract thought, problem solving, and language.

Corpus Callosum This is the biggest white matter structure in the brain which connects left and right hemispheres of the brain.

Corticospinal This means the tract begins in the cortex and ends in the spine.

Decussate This means "to cross over".

Dermatome This comes from the Greek word’s derma (skin), and tomos (section).

Dorsal Column This is the middle posterior area of white matter in the spinal cord.

Efferent This means it carries information away from the central nervous system

Hypertonia This is an abnormal increase in muscle tone.

Hyporeflexia This is a small, or absent reflex.

Hypotonia This describes low muscle tone.

Ischemia This is a restriction in tissue blood supply.

Lower Spine This is also be referred to as the lumbar region.

Medulla Oblongata These come from the Latin words “medulla” (pith), and oblongata (elongated).

Motor Homunculus This is a mapped representation of the motor neurons in the body corresponding to body parts in the primary motor cortex.

Muscle Atrophy This is the wasting away of the muscle.

Muscle Twitches These are caused by the spontaneous contractions of groups of muscle fibres.

Myelin This is a white substance that surrounds some neuron axons. It acts as an insulating layer, which increases the speed and distance at which a signal can traverse along the nerve.

Olfactory This means relating to the sense of smell.

Paralysis This refers to the complete loss of muscle movement.

Parasympathetic Nervous System This activates tranquil functions, such as stimulating the secretion of saliva or digestive enzymes into the stomach and small intestine.

Paresis This refers to the partial loss or weakness of muscle movement.

Plexus This is the Modern Latin word for "braid / network".

Pons This is the Latin word for "bridge".

Proprioception This is the sense of where the body is in relation to itself and its surroundings. It comes from the Latin words proprius (individual), and capio (to grasp).

Somatic Nervous System This is made up of nerves that connect to voluntary skeletal muscles and to sensory receptors. It is composed of afferent nerves that carry information to the central nervous system (spinal cord) and efferent fibres that carry neural impulses away from the central nervous system.

Somatosensory These are sensations that can occur anywhere in the body.

Spasticity This describes the combination of paralysis and hypertonia - the inability to move muscles which are tense and contracted (often painfully).

Sensory Homunculus This is a representation of the localization of the different regions of the body in the somatosensory cortex.

Sympathetic Nervous System This is involved in the stimulation of activities that prepare the body for action (fight‐or‐flight responses).

Thalamic Nuclei These are clusters of cells involved in relaying sensory and motor signals to the cerebral cortex. Every sensory system (except the olfactory system) includes a thalamic nucleus in the

pathway between the receptor and the associated primary cortical area. Signals from the cerebellum and the basal ganglia are relayed through thalamic nuclei.

Wernicke's Area This is involved in language comprehension. People with damage to this area are unable to understand language, both spoken and written, and can still speak with normal fluency, but their sentences may be meaningless. This is called receptive aphasia.

Cerebellum This controls the rate, range, and direction of movement and processes sensory information. It’s also involved in posture and balance, and plays an important role in learning and executing motor skills

Cerebellum Injuries Damage to the cerebellum does not prevent a person moving, but it does make actions hesitant and clumsy, and affects balance and gait. We can assess

cerebellar function by examining gait, balance (with eyes open and then shut), and finger to nose testing. People with cerebellar lesions will have difficulty with balance, even with their eyes open. They also have difficulty when asked to perform accurate rapid alternating movements. For example, repeatedly touching his or her own nose and then the examiner’s finger or demonstrating how to screw a lightbulb into a socket.

Diencephalon This sits at the top of the brain stem and is made up of the thalamus, subthalamus, hypothalamus, and epithalamus. It receives sensory inputs from every part of the body (except for olfactory inputs) and distributes this to the appropriate regions of the brain. It regulates the endocrine and autonomic systems. This is covered by the cerebrum and is only visible in brain scans or when the brain is dissected.

Thalamus This is the top centre portion of the diencephalon. It’s the relay station for sensory information and is composed of numerous thalamic nuclei, each with a functional specialty. It’s responsible for mediating sensation, motor activities, cortical arousal, learning, and memory.

Hypothalamus This is the lower, frontal part of the diencephalon. Below this is the optic chiasm (where the optic nerves cross)

and the pituitary gland. This is both a nervous and endocrine organ, which mostly maintains homeostasis. The main functions are: - Autonomic control centre. - Centre for emotional response. - Regulation of body temperature. - Regulation of food intake. - Regulation of water balance and thirst. - Regulation of sleep-wake cycles. - Control of endocrine system functioning.

Subthalamus

This is below the thalamus and above/behind the hypothalamus. The main structure is the subthalamic nucleus which may have a role in the processing that occurs in the basal ganglia.

Epithalamus This is behind/below the thalamus and acts as a relay station between the senses and the cerebral cortex. The pineal gland is part of this (the back bit).

Brain Stem This is continuous with the spinal cord and acts as a relay station between the spinal cord and the brain's cerebral hemispheres. This is the entry and exit point for 10 cranial nerves. It’s made up of the midbrain, pons, and medulla oblongata.

Midbrain This is at the top of the brainstem, under the thalamus. It contains fibres linking different components of the motor systems (cerebral hemispheres, cerebellum, and basal ganglia). This is involved in voluntary movement, motor functions, coordination of visual and auditory reflexes, the regulation of circadian rhythms, and thermoregulation.

Pons This is the middle region of the brainstem (under the midbrain, above

the medulla, and which contains a ventral bulge. This is composed mostly of white matter tracts and nuclei, which relay signals from the forebrain to the cerebellum. It’s also involved in the control of sleep, respiration, swallowing and taste, bladder control, equilibrium, eye movement, facial expression and sensation, and posture.

Medulla Oblongata This makes up the lower portion of the brainstem and is continuous with the spinal cord. White matter structures (the pyramids) contain motor fibres of the corticospinal and corticobulbar tracts which carry motor signals from the brain to the medulla and spinal cord. It’s also involved in the regulation of cardiovascular function, respiratory rhythm and digestion, and the regulation of reflexes such as vomiting, coughing, sneezing, swallowing, and hiccupping.

Spinal Cord This connects the brain to the rest of the body, providing neuronal pathways to and from the brain. Synapses occur all along the spinal cord between the central nervous system and peripheral nervous system neurons. This is the site of integration for involuntary reflexes below the head. Most incoming sensory neurons synapse when they enter the spinal cord. Most outgoing motor neurons originate in the spinal cord and send their axons into the periphery.

Gray Matter...