The forebrain contains
Subcortical structures (Hypothalamus, thalamus, basal ganglia, amygdala, cingulate cortex, and hippocampus) and the cerebral cortex.
The hypothalamus
Through effects on ANS and endocrine glands, the hypothalamus regulates homeostasis (body temp, heart rate, BP, appetite, thirst). Responsible for secondary sex characteristics and sexual/reproductive behaviors by stimulating the pituitary causing it to release sex hormones. Regulates the body’s response to stress by stimulating the pituitary to release ACTH.
Suprachaismatic Nucleas (SCN)
Located in the hypothalamus, serves as the bodies bio clock and controls circadian rhythms (physiological changes that occur during each 24 hr period- sleep/wake cycle, daily fluctuations of body temp, release of hormones). One way it does this is by controlling the pineal gland’s release of melatonin. Sensitive to light.
Mammillary bodies
Attached to hypothalamus, Important for memory, and damage interferes with the availing to form new declarative memories (which consists of somatic and episodic memories)
Thalamus
Relay station that receives and transmits sensory info to appropriate areas of the cortex for all senses except olfaction. It coordinates incoming sensory information with motor function regulated by the basal ganglia, cerebellum, motor cortex. Plays important role in memory.
Korsakoff syndrome
Thiamine deficiency due to alcohol, damages thalamus and mammillary bodies. Symptoms are anterograde amnesia (can’t form new memories), retrograde amnesia (loss of prior memory), and confabulation (filling in memory gaps with info the persons thinks is true).
The putamen and caudate nucleus are refered to as
Striatum
Basal ganglia
Includes caudate nucleus, putamen, and globus pallidus. Important for initiation and coordination of voluntary movement, emotional processing and responses, procedural and habit formation, attention, insight, planning, prioritizing, and other cognitive functions. Also sensitive to rewards ANS involved in rewards based associative learning. Damage has been linked to Huntington’s, Parkinson’s, Tourette’s, OCD, ADHD, and schizophrenia
The amygdala
Plays a role in emotional reactions especially fear and anger. It also attaches emotions to memories. It recognizes emotions in facial expressions. Bilateral damage causes Kluver-Bucy syndrome in monkeys. Abnormal functioning linked to ptsd, anxiety, and depression.
The hippocampus
Is involved more in learning than emotion. It is responsible for consolidating declarative memories (transferring declarative info from STM to LTM). People with damage have trouble storing new memories but can recall memories before the damage. Important for special memory. Linked to Alzheimer’s.
The cerebral cortex
Is divided into the right and left hemispheres. Each hemisphere contains a frontal, parietal, occipital,and temporal lobe.
The frontal lobe contains
Broca’s area (forming speech), prefrontal cortex (decision making, planning), and primary motor cortex (control of skeletal muscles). Important for executive functioning, planniing, insight, judgement, motivation, emotion regulation, working memory, and prospective (future) memory). Damage depends on location.
Dorsalatetal prefrontal cortex: contributes to most executive functions, and damage can cause impairments in goal directed behavior, concrete thinking, impaired judgment and insight, deficit in working memory, preservative responses, and is interested in apathy. It has been found to play a role in my depressive disorder, GAD, ODC, and schizophrenia
Ventrolateral prefrontal cortex: Involved and goal, directed behavior, decision, making, memory, motor, inhibition, and emotion regulation. Damage can cause apartments in decision, making and behavioral and emotional self control. Abnormalities are known to contribute to social anxiety disorder and generalized anxiety disorder.
Ventromedial prefrontal cortex: Is involved in decision-making, social cognition, memory, and emotion regulation. Damage can produce impaired decision-making and impaired moral judgment, lack of insight, confabulation, deficits in social cognition, such as impaired facial emotion, regulation, or reduced empathy, and blunted emotional responses. Abnormal activity in this area has been linked to a number of psychiatric disorders, including MDD, OCD; GAD, PTSD, and schizophrenia.
Orbitoftontal cortex: Plays a role in emotion regulation, response, in addition, and social behaviors. Damage can cause impulsivity, social inappropriateness (Such as immature behavior, inappropriate jocularity, inappropriate disclosure of personal information ), Lack of empathy, aggressive or abusive behaviors, and emotion dysregulation. Psychiatric disorders I have been linked to this area of abnormalities, include bipolar disorder, schizophrenia, substance use disorders, MDD, OCD, PTSD.
Primary motor cortex: Responsible for the initiation, a purposeful movements, and his active not only when people perform movements, but also when they imagine, performing down or watching another person perform them. The effects of damage to this area depend on this location and extent and range from witness to paralysis, and one or more muscles in the opposite side of the body.
The parietal lobe contains
Somatosensory cortex (sense of touch including pressure, pain, body positioning, and temp) and sensory association cortex (integration of sensory information) including body location.
Damage depends on location can cause one or more somatosensory agnosia including tactile ( cannot recognize by touch), asomatognosia (lack of interest/recognition of one or more ore parts of one’s body) and anosognosia denial of one’s illness or disability.
Damage can also produce one or more types of apraxia,
Contralateral neglect )usually damage to right hemisphere/non-dominant and involves in attention to one side of the body and visual field) or Gerstmann’s syndrome- (usually caused by damage to the dominant parietal lobe ( usually left hemisphere) and involves right-left disorientation, finger agnosia, agraphia (loss of writing skills) and acalulia ( loss of math skills).
Limb-kinetic apraxia (Can ability to make precise, coordinated movement, using your finger, hand, arms, or leg
ideomotor apraxia involves an inability to imitate a motor activity or perform motor activity in response to verbal request (Pretend to comb your hair)
Ideational apraxia Involves an inability to plan and execute the task that requires a sequence of actions, example inability to complete the steps needed to make a sandwich.
Contralateral apraxia Also known as unilateral neglect, and hemispatial neglect And is usually caused by damage to the right, non-dominant, parietal lobe and involves neglect of the left side of the body and stimuli on the left side of the body
The occipital lobe contains
Visual association cortex (combining images and object recognition) and visual cortex (processing visual stimuli and pattern recognition). Damage to this area can cause visual agnosia, VH, achromatopsia, or cortical blindness.
Damage or lesions to the occipitotemporal junction produces prosopagnosia or the inability to recognize faces of familiar people
The temporal lobe contains
-Auditory cortex (hearing) and Wernicke’s area (comprehending language).
The auditory cortex is involved in processing sound. Damage can cause auditory agnosia, AH, or cortical deafness.
-Wernecke’s area- major language area. Located in dominant hemisphere. Damage causes Wernecke’s aphasia (receptive aphasia) and involves impaired comprehension of written and spoken language, impaired repetition, and anomia. They also have fluent but incoherent meaningless speech. Although their speeches fluent, it contains many words, substitutions, and other errors, and is devoid of meaning.
Damaged areas of the prefrontal cortex
A. Dorsolateral area produces dysexecutive syndrome: impaired attention, working memory, and abstract thinking; depression and a decreased range of emotion; and perseveration
B. Orbitofrontal area produces disinhibition syndrome: behavioral disinhibition, distractibility, emotional lability, inappropriate euphoria, and acquired sociopathy (risk taking behavior, lack of empathy or insight, and persistent need for immediate gratification)
C. Mediofrontal area produces an apathetic-akinetic syndrome: decreased motor behavior and verbal output, lack of motivation and goal directed activities, apathy, and indifference.
The primary motor cortex is
Involved in executing voluntary movements by sending signals to the muscles. Damage depends on extent and location. Can cause weakness or paralysis in one or more muscles on the opposite side of the body.
Broca’s area
Major language area, located in the dominant hemisphere (usually left). Damage causes Broca’s aphasia (expressive aphasia): slow labored speech (nouns and verbs), impaired repetition, and anomia ( inability to recall the names of familiar objects. BUT their comprehension of written and spoken language is relatively intact.
What connects Wernecke’s to Brocas area?
The arcuate fasciculus (bundle of nerve fibers). Damage to this area causes conduction aphasia which is characterized by relatively intact comprehension, with fluent speech that contains many errors, impaired repetition, and anomia.
Structural Neuroimaging techniques used to identify structural changes due to stroke, illness, tumors, blood clots are
Cat (computerized axial tomography) uses X-rays to obtain images of horizontal slices of the brain. Cost less, pt not required to be still, can be used with pts with metal in body .
MRI (magnetic resonance imaging) uses strong magnetic fields and radio waves to obtain cross-sectional images of the brain. Produces 3-d images and no radiation, used for structural info about brain, spinal cord, and other structures of the body.
Functional neuroimaging techniques provide info aboiut brain structure and indirect info about neuronal activity by accessing cerebral blood flow, oxygen consumption, or glucose metabolism. They include-
PET (positive-emission tomography): injected with radioactive tracer taken up by active brain cells
SPECT (single proton emission computed tomography): easier, less expensive, but less detailed images
fMRI (functional magnetic resonance imaging): similar to MRI, but provide info in blood oxygenation and flow
Insular cortex
The fifth and smallest load of the cerebral cortex. Plays a role in a number of Functions. It is hidden within the lateral sulcus, which is also known as Sylvan Fissure, which is a deep groove that separates the frontal and parietal lobes from the temporal lobe.
Left hemisphere functions
For approximately 95% of right handed people and 50 to 70% of left-handed people, written and spoken language, logical and analytical, thinking, and positive emotions are left hemisphere functions.
Right hemisphere function
Holistic, thinking, intuition, understanding, spatial relationships, creativity, and negative emotions are right hemisphere functions. The right hemisphere is responsible for emotional prosody and pragmatics. Emotional prosody refers to the expression of emotion through variations and annotation, including manipulation of speech at the level of phrases or sentences, tone, stress, loudness, raped, and rhythm of speech. Pragmatics refers to the use an understanding of language in different situational and social contexts, Such as the use and understanding of humor, sarcasm, and hyperbole. There is also evidence that the right hemisphere is involved in identifying, basic sounds of language on infants, learning their native language, and adults learning a second language.
