BRAIN AND BEHAVIORHYACINTH C. MANOOD, MD, FPPA

FRONTAL LOBE:

Voluntary movement

Language production (left)

Motor prosody (right)

Comportment

Executive function

Motivation

TEMPORAL LOBES

Audition

Language comprehension (left)

Sensory prosody (right)

Memory Emotion

PARIETAL LOBES:

Tactile sensation

Visuospatial function (right)

Reading (left) Calculation (L)

OCCIPITAL LOBES:

Vision

Visual perception

THE BASAL GANGLIA Mediate postural tone PARTS:1. Corpus striatum – caudate and putamen

Caudate acts as gatekeeper to allow the motor system to perform only those acts that are goal-directed. Studies correlated decreased activation of caudate with OC behavior, Tics and Tourette’s disorder.

2. Globus pallidus - receives input from the corpus striatum and projects fibers to the thalamus. This is damaged in Wilson’s disease and carbon monoxide poisoning, resulting in dystonic posturing and flapping movements of arms and legs.

3. Substantia nigra – degenerates in Parkinson’s disease

4. Subthalamic nucleus – yield ballistic movements, sudden limb jerks.

THE AUTONOMIC MOTOR SYSTEM

PARASYMPATHETIC – slows heart rate and begins the process of digestion.

SYMPATHETIC – mediates flight or fight response, with increased heart rate, shunting of blood away from the viscera, and increased respiration.

Limbic System

The limbic system is comprised ofHippocampus: involved in

learning and memoryAmygdala: involved in

emotion; may mediate anxiety and panic

Mammillary BodiesThe fornix is a fiber

bundle that interconnects the hippocampus with the mammillary bodies

The limbic system had been implicated in neuropathological studies of schizophrenia. The 4 A’s of Eugen Bleuler refer to brain functions served in part by the limbic structures.

NEUROTRANSMITTERS

BIOGENIC AMINES:• Dopamine• Serotonin• Norepinephrine• Epinephrine• Histamine• Acetylcholine

AMINO ACIDS:• Glutamate• GABA• Glycine

NEURO-PEPTIDES• Substance P• Neurotensin• Cholecystokini

n• Somatostatin• Oxytocin and

Vasopressin• Neuropeptide Y

DOPAMINE

DA Tract Origin Innervation Function

Nigrostriatal Substantia nigra

Caudate nucleus

Extrapyradimal movement

Mesolimbic Ventral tegmental area

Limbic areas Arousal, memory, stimulus processing, behavior

Mesocortical

Ventral tegmental area

Frontal and pre-frontal cortex

Cognition, communication, social functionStress response

Tubero-infundibular area

Hypothalamus Pituitary gland

Regulates prolactin release

SEROTONIN• Serotonin is synthesized from the amino acid Tryptophan.

• The synthesis of serotonin involve two reactions:

1)     1) Hydroxylation:

Tryptophan 5- Hydroxytryptophan

• The enzyme catalyzes this reaction is Tryptophan Hydroxylase.

The Co- factor is Tetrahydrobiopterin, which converted in this reaction to Dihydrobiopterin.

2)      2) Decarboxylation:

5- hydroxytryptophan Serotonin

The enzyme is hydroxytryptophan decarboxylase.

• Serotonin is synthesized in CNS, & Chromaffin cells.

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Break down of serotonin:

Serotonin is degraded in two reactions

1) Oxidation:5-hydroxytryptoamine + O2 + H2O 5-

Hydroxyinodole-3-acetaldehyde

2) Dehydrogenation5- Hydroxyinodole-3-acetaldehyde 5-hydroxindole-3-

acetate

(Anion of 5-hydroxyindoleacetic acid)

Monoamine oxidase

Aldehyde dehydrogenase 

The serotonergic pathway showing the effects of

schizophrenia

The two key serotonergic pathways in schizophrenia are the projections from the dorsal raphe nuclei into the substantia nigra and the projections from the rostral raphe nuclei ascending into the cerebral cortex, limbic regions and basal ganglia. The up-regulation of these pathways leads to hypofunction of the dopaminergic system, and this effect may be responsible for the negative symptoms of schizophrenia. The serotonergic nuclei in the brainstem that give rise to descending serotonergic axons remain unaffected in schizophrenia.

AMINO ACIDS

Amino acids are the most abundant neurotransmitters in the brain. Nichols suggested: “amino acids synapses exceed those of all the other neurotransmitters combined…amino acids are responsible for almost all the fast signaling between neurons, leaving predominantly modulatory roles for the other transmitters.”

Glutamate is the major excitatory neurotransmitter and is distributed in all regions of the brain. The major conditions associated with this NT are EXCITOTOXICITY and SCHIZOPHRENIA.

GABA is the major inhibitory NT. The major conditions associated with this are ANXIETY and SEIZURE DISORDER.

Glycine does double duty as a mandatory adjunctive NT for glutamate activity and as independent inhibitory NT at its own receptors. Improvement of NMDA receptor activity by occupancy of the glycine-binding site has been hypothesized to present an adjunctive mode for the treatment of shizophrenia.

Neuropeptides

Function of Neuropeptides:  There are cells in the brain that produce various neuropeptides, and these neuropeptides do just about everything. They can be either pro-inflammatory or anti-inflammatory, with anti-inflammatory being preferred. They are responsible for many functions: They control our mood, energy levels, pain and pleasure reception, body weight, and ability to solve problems; they also form memories and regulate our immune system. These active little messengers in the brain actually turn on cellular function in the skin.

Substance P – Huntingtons dse., dementia of the Alzheimer’s type, and mood disorders.

Neurotensin – involved in pathophysiology of schizophrenia.

Cholecystokinin – causes anxiety and triggers panic attacks in people with panic disorder.

Somatostatin – Huntington’s disease and dementia of the Alzheimer’s type.

Vasopressin and Oxytocin - involved in regulation of mood.

Neuropeptide Y – stimulates appetite.

THANK YOU & GOOD DAY