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Unit 1 Organization of the Nervous System Lesson 1 The Cerebral Cortex, the Cortical Lobes, and their functions An undiscovered country The origins of the study of brain and behaviour started in Montréal 1934 Neuro surgeon DR Wilder Penfield founded the Montréal neurological institute. At this time the brain was still an undiscovered country. Symptoms, Development, Anatomy of Parkinson’s Disease The brain and central nervous system is vital in our motor ability, these systems are generally devoted to movement. When the brain does not work it can lead to movement disorders that can affect our ability to move and have disturbing effects on the individuals suffering from them. Parkinson’s Disease is a progressive neurological disorder, which result in reregulation of dopamine producing brain cells of the substantia nigra, which is located in the mid brain found mainly in the central nervous system. Vision movement and hearing are related to the midbrain. These neurons that release dopamine are called dopaminergic neurons and play a key role in initiation of controlled and smooth movement. Dopamine producing brain cells of the substania nigra are located above where the spinal cord meets the midbrain. The execution of movement begins in the motor cortex and the basal ganglia. The brain structures affected by Parkinson’s disease are the basal ganglia. The basal ganglia network includes the caudate nucleus, the putamen, the globus pallidus, and the subthalamic nucleus and the substantia nigra. Neurons are responsible for sending and receiving messages between the body and the brain. The structures work together to control our movements. Basal ganglia turns thought about movement into action. This area is pertinent for learning normal movements. The irregularity of dopamine results in Parkinson’s disease. The planning of movement takes place in prefrontal cortex by using auditory and visual information about the world around us, information about our bodies and its spatial awareness it retains the information in the memory while deciding on a subsequent action. The information travels to the premotor cortex and then to the supplementary motor where the voluntary movement is organized and implemented. When neurons are fired within the primary motor cortex during a movement it also determines how much strength will be put into the movement and the direction of that movement. The brain uses dopamine to send message to help control movement. The Substantia Nigra part of basal ganglia connects to the motor cortex. Substantia nigra which receives signals from a part of the basil grangria produces dopamine, these dopamine neurons project dopamine-releasing axons to the striatum which is composed of the basal gangla’s caudate and putamen. When the cells in the substantia nigra have stopped working or perish results in the inability to produce enough dopamine to control movements appropriately. This is when symptoms of Parkinson’s arise; they are characterized by tremors, slowness and stiffness, poor balance, ridgity of the muscles, and have difficulty in initiating movement. Treatment of Parkinson’s disease and the side effects The available treatments for Parkinson’s disease are Chemical L-dopa, and Deep Brain Stimulation. L-Dopa is a chemical that the brain uses to replicate dopamine. Chemical L-dopa is

a drug chemical that allots the patients brain to quickly transform the chemical into dopamine so that they are able to counterbalance the damage of dopamine neurons. Due to the fact that dopamine cannot cross the blood brain barrier L-dopa is invaluable as it can cross the barrier and generate dopamine. However, L-Dopa is not a cure but rather a treatment thus as more neurons degenerate increased doses of L-Dopa are required. L-Dopa creates dopamine within the body when dopamine neurons die replacements are needed to maintain balance. Thus an Increase in dose of L-Dopa is required. Secondly deep brain stimulation is an alternative treatment for Parkinson’s disease though not as good as L-dopa. Deep Brain Stimulation is a new surgical invention, which involves deep brain stimulation. Deep brain stimulation involves the placement of an electrode into the patient’s brain and the dopamine neurons in the substania nigra are stimulated to fire to specific areas within the brain. The neurons firing reduce some symptoms. However, there are side effects to this treatment. Some side effects include increased gambling, hyper sexuality, and compulsive eating. These side effects arise as dopamine fires and over stimulate the wrong sections of the brain and not in the correct quantities, thus making it difficult to resist impulses as in compulsive eating, increase competitiveness as the result in gambling and hyper sexuality in relation to sexual desire. Parkinsonaian –like symptoms occurring in patients taking antipsychotics Symptoms of Parkinson’s can be seen within patients whom take antipsychotics. Antipsychotics are psychotherapeutic drugs used for patients with schizophrenia. Schizophrenia is the result of excessive dopamine to the brain. The symptoms include what is referred to as the positive symptoms, symptoms not seen in individuals without schizophrenia such as hallucination, bizarre behaviour etc. The negative symptoms are seen within healthy people but no those with the disease like social withdrawal, reduced speech etc. lastly the cognitive symptoms include the inability to contemplate and put forth normal cognition such as impaired working memory or inability to plan and cook a meal. The latter is the most debilitating symptoms. “Antipsychotic drugs block dopamine D2 receptors in the striatum and treat the positive symptoms and not the negative nor the cognitive one.” Antipsychotic drugs are the main drugs used to treat schizophrenia they have severe side effects that impair movements that result in patients resembling those with Parkinson’s disease. These effects can include spasms, rigidity, jerky and involuntary movements. Some parts of the brain in the patients with schizophrenia have too much dopamine and others do not. Thus because the striatum is part of the basal ganglia which is important for initiation and smooth movement deterioration of dopamine to that area results in Parkinson’s disease, thus blocking dopamine to that area results in similar behaviours. Recent Reach on Parkinson’s disease In a study conducted by Guntekin et al. (2018), it was investigating the delta responses in Parkinson’s disease (PD) patients with cognitive deficits. The goal of the study was to fill a gap and study the delta responses in PD patients with cognitive deficits in comparisons to those with PD whom do not have a deficit and to others that are healthy, in order to determine if there will be an increase in cognitive load and delta responses (Guntekin et al, 2018). The researcher assembled 32 patients with Parkinson’s disease 12 without any cognitive deficits and 10 that have Parkinson’s disease with mild cognitive impairment, and 16 healthy subjects (Guntekin et al, 2018). The researcher applied auditory stimuli and auditory oddball paradigms (Guntekin et al, 2018). The maximum amplitudes of each subject’s delta response were the same and measured for each electrode and stimulation. (Guntekin et al, 2018). Upon conducting this test it

was noted that there was difference between the groups specific to stimulation. Patients with Parkinson’s disease with mild cognitive deficit and those without had reduced delta responses than the healthy controlled group after stimulation of target areas (Guntekin et al, 2018). The non- target and simple auditory stimulation delta responses gradually decreased in patients with PD and a mild cognitive deficit. The conclusions of the study were that the results of the study show that a decrease in delta responses during auditory stimulation depicted a cognitive decline in Parkinson’s disease (Guntekin et al, 2018). In the healthy controls the target stimulation prompted higher delta responses than non-targeted stimulation and simple auditory stimulation (Guntekin et al, 2018). Also, the delta responses on the healthy individuals were higher than in the other subjects (Guntekin et al, 2018). The decrease in delta response is related to cognitive decline, which is an electrophysiological indicator of cognitive impairment (Guntekin et al, 2018). Dr Penfield realized :  Discvovered it was possible to perform brain surgery on patients while they were still awake. o Using sensitive electrical probe to study the effects of brain stimulatons on the body.  Removed skull of awake patient underanesthitest and apply the probe to various parts of the cortex. Patients were able to tell him what they were feeling when a particular brain area was stimulated.  Using this technique he was able to pamp various areas of the cortex including the somatosensory cortex and the motor cortex. Wilder Penfield short video- went to Oxford. lead to work on tumors, brain scars and epilepsy.  Discovered that he could sum up past experiences in his patients by mildly shocking the temporal lobe stimulating memory. Surgical experiences and research made him one of the giants of neiro pathology and neuro sugery.

The four Lobes The cortex divided into four main lobes. Named after the bones of the skull that cover them. 1. Frontal lobe 2. Parietal lobe 3. Occipital lobe 4. Temporal lobe The cortex is divided into two cerebral hemispheres  Left hemisphere  Right hemisphere These two dominate the appearance. Look like mirror images Right hemisphere:  Right controls the left side of the body Left hemisphere:  Left hemisphere controls the left side of the body.

Convolutions (fold, wrinkles like a walnut) of the Cortex The reason we have convolutions is to give greater surface area of the cortical brain tissue to fit into a skull. Does Size Matter? Size: Brain size has little to do with intelligence but correlates to body size. Men and women don’t differ in IQ. Women have smaller brains than men. What does differ is the amount of convolutions in the cortex Convolutions and intelligence The more convoluted the cortex the smarter the animal. Gyrus, Sulcus, and Fissure Convolutions are comprised of ridges and valleys Ridge: right side : Precentral gyrus (motor cortex) called a Gyrus Left side: Postcentral gyrus (somatosensory cortex) Central Sulcus: the space or groove between the gyrus. If it’s a very large sulcus its called a fissure. The longest fissure is called the longitudinal fissure divides the left from right hemisphere. The Lateral fissure divides the temporal lobe from the frontal and poriltal lobes. Greyish appearance of cortex Cortex composed primarily of Neuronal cell bodies. Which make them look grey= grey matter. Other parts of the body comprised of tracks ofAxon that transmits from one part of the brain to the other covered in Milan a fatty substance covered in white = white matter Pariental lobe Exercise The Cortical Lobes 

Frontal Lobe: when damaged change in personality. Inability to act normal in social situations results I ,loss of friends etc. o Stoke or trauma o Change in personality o Severe personality changes when damaged. Frontal lobe lobotomies performed 1940s and 50 as a treatment for illness entered skull through hole in back of eyes socket. Disconnected frontal lobe to the rest of the body. From depression to schizophrenia. o Planning and organization o Impulse control adjusting behaviour

o Decision-making o So important develops last area to develop. Until Late teens or early 20s Importance in impulse control (understandable why children have a hard time sitting in class) 

Frontal Lobe o Carries out functions we tend to think make us uniquely human o Brocas’ area controls speech production  Speech production, speech and grammatical structure. o Precentral gyrus  Extends the length of central sulcus, it is the location of the primary motor cortex which controls voluntary movement – one of the areas mapped out by dr. penfield. By stimulation various areas of the cortex. Called a “motor homunculus” each area of the cortex has its own homunculus. One on right controls the left side of the body and the one on the left controls the right side of the body o Temporal Lobe  Lateral fissure separates the temporal lobe from the frontal and parietal lobes.  Contain the auditory projection areas, visual and auditory association areas  And an additional language area called the auditory cortex. Which perceives sound information from the ears) Lies on the upper most gyrus of the temporal lobe. Mostly hidden from view within the lateral fissure.  Wernicke’s area. An association area that interprets language input arriving from nearby auditory and visual areas. When the Wernicke’s area is damaged you have trouble understanding speech or writing. They can speak but mostly it sounds like gibberish. Both Wernickes’s area and Brocas area are found in the left hemisphere in most right-handed ppl. If a child damages their brocas or Wernicke’s area of their brain damaged they can still manage to develop speech later in life, because the alternative hemisphere would take over in the ability to speak and understand spoken word. o Parietal Lobe  Located superior to the lateral fissure and between the central sulcus and the occipital lobe.  Contains the primary Somatosensory cortex also mapped out by Dr penfield. Located on the post central gyrus. Process skin senses such as touch, warmth, cold, pain and senses that informs us about the body’s position and movement. o Occipital lobe  Back of the brain  Important for vision.  Contain visual cortex and visual association areas were visual components are processed  Including individual components of a scene= color, movement and form....