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Neuroanatomy & Psychiatric Disorders - prereading

Planes of the brain

  • White matter": Mainly axons due to myelination (lipid/ fatty sheath)

  • Grey matter: neuronal cell bodies

Main regions of the brian

Embryology

  • Refer back to case 7 embryology on the formation of the spinal cord

  • The neural tube then splits into the main parts of the brain

Rhombencephalon

  • Brain stem

  • Cranial nerves + normal nerves run from the medulla

  • The cerebellum + pons are important in co-ordinating movements + responding to external stimuli

Cerebellum - divided i nto 3 lobes:

  1. Flocculonodular lobe

    • Vestibulocerebellum/ archicerebellum

    • Regulates balance + co-ordination (oldest)

  2. Posterior lobe

  3. Anterior lobe

  4. Contains Purkinjie + granule cells

  • Areas closest to the vermis- spinocerebellum/ paleocerebellum

  • Spinocerebellum: regulates body temperature + limb movement

  • Laterally- neocerebellum

  • Neocerebellum:

regulates planning,

sensory movement for action

Cerebellar Disorders

  • Damage of the neocerebellum causes ataxic gait e.g. stroke or alcohol-related

  • Cerebellum has a complex arterial supply

  • Therefore, it is important in cases of stroke or vertebral/ basilar artery dissection (present with cerebellar signs

Pontine disorders

  • locked-in syndrome

  • Central pontine myelinolysis

  • Progressive Supranuclear Palsy (Steele-Richardson-Olszewski):

    • Supranuclear ophthalmoplegia

    • Neck dystonia

    • Parkinsonism

    • Pseudobulbar palsy

    • Behavioural impairment

    • Imbalance

    • Frequently falls

Reticular formation

  • Allows for communication of the brain to the rest of the body

  • A hub for the synthesis of neurotransmitters and wake/sleep state

  • Ascending/ descending through the brainstem

  • Includes ascending reticular activating system- role in arousal

Mesencephalon

  • Midbrain

  • Acts as a connector between different parts of the brain

  • links everything together

  • Don’t worry too much about the next info

Parts of the midbrain

  • Tectum (dorsal part) splits into:

  • Superior colliculus- visual processing + eye movement control

  • Inferior colliculus- auditory processing

Disorders of the mesencephalon

  • Parkinson’s - reduction in dopaminergic neurones in substantia nigra

  • Schizophrenia- increased dopamine in substantia nigra

  • Multi-system atrophy- degeneration of striatum and substantia nigra

  • Ventral tegmental area- primary sites of addictive drugs (heroin, cocaine, alcohol, nicotine)

Diencephalon

Contains:

  • Thalamus

  • Hypothalamus

  • Pineal Body

  • Subthalamus

  • Epithalamus

  • Mammillary bodies

Limbic system:

  • Connects cortical control to memory / sensory/ secretory areas

  • Involved in motivation, visceral processes + rewards

  • Systems of emotions

  • Connects a group of structures surrounding the brainstem (cingulate gyrus, hippocampus, hypothalamus + anterior thalamic nuclei)

  • Connecting these structures enables cortical control of emotion + plays a role in storing memory

Telencephalon

  • higher functions such as smell, memory + Intelligence

Hippocampus

  • Medial temporal lobe

  • Short-term memory to long term memory

  • Spatial memory

  • Includes dentate gyrus + granule cells - formation of new episodic memories, site of neurogenesis, affected in depression

  • Alzheimer’s + dementia → hippocampal atrophy → memory symptoms

Cortex

  • Memory

  • attention

  • Cognition

  • awareness

  • thought

  • language

  • consciousness

  • 4 lobes, gyrus (fold) + sulcus

Frontal lobe

  • Superior frontal gyrus = self-awareness/ laughter

  • Middle frontal gyrus

  • Inferior frontal gyrus = language processing, Broca’s area

  • Medial frontal gyrus = executive mechanism

  • Paraolfactory area= limbic

  • Orbitofrontal cortex= stimulus-reward, stimulus/outcome, addiction

  • Ventromedial prefrontal cortex- decision making, emotion regulation, addiction

  • frontotemporal dementia/ Pick’s disease = genetic + accumulation of tau + frontal symptoms

Prefrontal cortex

  • Planning + executing actions

  • One of the last to develop

  • lesions:

    • Dramatic changes in personality

    • Loss of spontaneity/ problems with initiating speech/ movements

    • inability to make + carry out sequences of actions/plans

Parietal lobe

  • Integrates sensory information

  • Dominant hemisphere lesions:

    • Dysphasia, aphasia

    • Dyscalculia- difficulty learning, doing calculations

    • Dyslexia

    • Apraxia- ability to execute or carry out skilled movements and gestures, despite having the desire and the physical ability to perform them.

    • Agnosia- inability to recognize and identify objects or persons.

    • Gerstmann syndrome- Dyscalculia, Dysphasia, finger agnosia, LR disorientation

  • Non- dominant hemisphere lesions:

    • Spatial disorientation

    • Constructional apraxia

    • Dressing apraxia

    • anosognosia- unaware of their own health problems

Temporal lobe

  • Transeverse temporal gyri - Heschl’s gyri

  • Superior temporal gyrus= auditory context with TTG. Pricess perception of sound + apply comprehension.

  • Posterior STG = wernicke’s area

  • Middle temporal gyrus

  • Fusiform gyrus = FACIAL RECOGNITION, synaesthesia, dyslexia, prosopagnosia

  • Inferior temporal gyrus= visual object recognition

Occipital lobe

  • Lingual gyrus

    • role in vision + dreaming

    • Visuo-limbic integration

    • encoding complex images

    • word processing

  • Cuneus - basic visual processing

  • Calcarine sulcus/fissure

    • primary visual cortex

    • takes signals from geniculate nucleus via thalamus

Tracts- only for reference

  • Arcuate fasciculus- links Broca’s + Wernicks area

  • Uncinate fasciculus

    • Links temporal inferior frontal gyrus + frontal lobe

    • Hippocampus + amygdala with orbitofrontal cortex

    • implicated in several psych conditions

  • 2 visual streams hypothesis:

    • dorsal - where?

    • ventral- what?

Central dopamine hypothesis

  • Meso-cortical pathway

  • Meso-limbic pathway

  • Nigrostriatal pathway

  • Affected in schizophrenia + other psych disorders

  • Medications for scz work on this pathway

  • Side effects of these meds are linked to these pathways (e.g. cog-wheel rigidity like that seen in parkinson’s/ galactorrhea due to pituitary stimulation)

Alzheimer’s Dementia

  • Microscopic accumulations of peptide amyloid-β – plaques → cause loss of synapses, then neurons.

  • Progressive degeneration

  • Early changes in the hippocampus (first to be damaged)

Generalised shrinking and enlarged ventricles follow

  • In severe depression, the dentate gyrus don’t light up in the scans which means they don’t form many memories.

Drug misuse

  • The reward system is based on dopamine.

  • It activates all dopamine pathways, particularly the mesolimbic pathway.

  • Dopamine is produced in the Vental Tegmental Area (VTA).

  • The mesolimbic pathway links this to the Nucleus Accumbens (motivation/ reward).

  • If we do something good, or use an addictive drug, this pathway is stimulated.

  • The mesocortical pathway is also activated.

  • This links to the Prefrontal Cortex (PFC).

  • This changes how you prioritise and plan.

Disorders

Case 1- depression after frontal tumour

  • 56 year old female

  • Progressive apathy

  • Social withdrawal

  • Poor self-care for part 3 years

  • Admitted to a psychiatric facility for depression

  • unresponsive to antidepressants so CT was conducted

  • 8cm medial bifrontal mass

  • Total excision benign transitional-type meningioma → rapid improvement

  • 4 months after the operation was cheerful + motivated

Case 2- Psychosis after temporal tumour

  • 18-year-old female

  • Referred form school to a psychosis clinic (high risk)

  • 2 years of withdrawal from social activities + resent from work groups or talking in public

  • 1 year later became concerned about unknown people stating + laughing at her for no reason

  • Feeling the world around her has changed

  • She is concerned that people are intimidating her + that there are special messages in TV for her

  • She is neurologically normal + an average IQ

  • Initial diagnosis: prodromal syndrome of schizophrenia but symptoms became more rapidly severe

  • Routine MRI conducted

  • Tumour in the left temporal lobe - dysembryoplastic neuroepithelial tumour (DNET)- usually benign glial neural neoplasm

  • Surgically remove

  • Psychotic symptoms improved with the help of other treatments- risperidone + CBT

  • However, remained socially withdrawn

Case 3- bipolar effective disorder due to Wilsons disease

  • Middle aged female

  • Detained + admitted under section 2 of the Mental Health Act (MHA) 2007- decline in her mental state

  • Initially aggressive behaviour + required restrain by the Emergency Department security + police

  • Quietly spoken

  • voicing paranoid persecutory delusions

  • euthymic with labile affect

  • alternating between anger

  • tearfulness

  • displaying disinhibited affection

  • Doesn’t know why she was presented

  • CT

  • Hypodensity in the putamen, worse on the left

  • No mass, infarct or infectious process to explain the lesions

  • Consistent with the MRI from a couple of months ago which demonstrates hyperintensity of both putamina

  • Associated with Wilson’s disease

  • final diagnosis: psychosis secondary to neurological Wilson’s Disease

Case 4- Psychiatric syndromes associated with neurological disease

  • 63-year-old male

  • paranoia

  • impaired anterograde memory + fatigue

  • FLAIR scan shows bilateral hyperintensities in the hippocampus (arrows) → shows inflammatory process

  • Blood tests revealed anti-voltage gated potassium channel antibodies

Neuroanatomy & Psychiatric Disorders - prereading

Planes of the brain

  • White matter": Mainly axons due to myelination (lipid/ fatty sheath)

  • Grey matter: neuronal cell bodies

Main regions of the brian

Embryology

  • Refer back to case 7 embryology on the formation of the spinal cord

  • The neural tube then splits into the main parts of the brain

Rhombencephalon

  • Brain stem

  • Cranial nerves + normal nerves run from the medulla

  • The cerebellum + pons are important in co-ordinating movements + responding to external stimuli

Cerebellum - divided i nto 3 lobes:

  1. Flocculonodular lobe

    • Vestibulocerebellum/ archicerebellum

    • Regulates balance + co-ordination (oldest)

  2. Posterior lobe

  3. Anterior lobe

  4. Contains Purkinjie + granule cells

  • Areas closest to the vermis- spinocerebellum/ paleocerebellum

  • Spinocerebellum: regulates body temperature + limb movement

  • Laterally- neocerebellum

  • Neocerebellum:

regulates planning,

sensory movement for action

Cerebellar Disorders

  • Damage of the neocerebellum causes ataxic gait e.g. stroke or alcohol-related

  • Cerebellum has a complex arterial supply

  • Therefore, it is important in cases of stroke or vertebral/ basilar artery dissection (present with cerebellar signs

Pontine disorders

  • locked-in syndrome

  • Central pontine myelinolysis

  • Progressive Supranuclear Palsy (Steele-Richardson-Olszewski):

    • Supranuclear ophthalmoplegia

    • Neck dystonia

    • Parkinsonism

    • Pseudobulbar palsy

    • Behavioural impairment

    • Imbalance

    • Frequently falls

Reticular formation

  • Allows for communication of the brain to the rest of the body

  • A hub for the synthesis of neurotransmitters and wake/sleep state

  • Ascending/ descending through the brainstem

  • Includes ascending reticular activating system- role in arousal

Mesencephalon

  • Midbrain

  • Acts as a connector between different parts of the brain

  • links everything together

  • Don’t worry too much about the next info

Parts of the midbrain

  • Tectum (dorsal part) splits into:

  • Superior colliculus- visual processing + eye movement control

  • Inferior colliculus- auditory processing

Disorders of the mesencephalon

  • Parkinson’s - reduction in dopaminergic neurones in substantia nigra

  • Schizophrenia- increased dopamine in substantia nigra

  • Multi-system atrophy- degeneration of striatum and substantia nigra

  • Ventral tegmental area- primary sites of addictive drugs (heroin, cocaine, alcohol, nicotine)

Diencephalon

Contains:

  • Thalamus

  • Hypothalamus

  • Pineal Body

  • Subthalamus

  • Epithalamus

  • Mammillary bodies

Limbic system:

  • Connects cortical control to memory / sensory/ secretory areas

  • Involved in motivation, visceral processes + rewards

  • Systems of emotions

  • Connects a group of structures surrounding the brainstem (cingulate gyrus, hippocampus, hypothalamus + anterior thalamic nuclei)

  • Connecting these structures enables cortical control of emotion + plays a role in storing memory

Telencephalon

  • higher functions such as smell, memory + Intelligence

Hippocampus

  • Medial temporal lobe

  • Short-term memory to long term memory

  • Spatial memory

  • Includes dentate gyrus + granule cells - formation of new episodic memories, site of neurogenesis, affected in depression

  • Alzheimer’s + dementia → hippocampal atrophy → memory symptoms

Cortex

  • Memory

  • attention

  • Cognition

  • awareness

  • thought

  • language

  • consciousness

  • 4 lobes, gyrus (fold) + sulcus

Frontal lobe

  • Superior frontal gyrus = self-awareness/ laughter

  • Middle frontal gyrus

  • Inferior frontal gyrus = language processing, Broca’s area

  • Medial frontal gyrus = executive mechanism

  • Paraolfactory area= limbic

  • Orbitofrontal cortex= stimulus-reward, stimulus/outcome, addiction

  • Ventromedial prefrontal cortex- decision making, emotion regulation, addiction

  • frontotemporal dementia/ Pick’s disease = genetic + accumulation of tau + frontal symptoms

Prefrontal cortex

  • Planning + executing actions

  • One of the last to develop

  • lesions:

    • Dramatic changes in personality

    • Loss of spontaneity/ problems with initiating speech/ movements

    • inability to make + carry out sequences of actions/plans

Parietal lobe

  • Integrates sensory information

  • Dominant hemisphere lesions:

    • Dysphasia, aphasia

    • Dyscalculia- difficulty learning, doing calculations

    • Dyslexia

    • Apraxia- ability to execute or carry out skilled movements and gestures, despite having the desire and the physical ability to perform them.

    • Agnosia- inability to recognize and identify objects or persons.

    • Gerstmann syndrome- Dyscalculia, Dysphasia, finger agnosia, LR disorientation

  • Non- dominant hemisphere lesions:

    • Spatial disorientation

    • Constructional apraxia

    • Dressing apraxia

    • anosognosia- unaware of their own health problems

Temporal lobe

  • Transeverse temporal gyri - Heschl’s gyri

  • Superior temporal gyrus= auditory context with TTG. Pricess perception of sound + apply comprehension.

  • Posterior STG = wernicke’s area

  • Middle temporal gyrus

  • Fusiform gyrus = FACIAL RECOGNITION, synaesthesia, dyslexia, prosopagnosia

  • Inferior temporal gyrus= visual object recognition

Occipital lobe

  • Lingual gyrus

    • role in vision + dreaming

    • Visuo-limbic integration

    • encoding complex images

    • word processing

  • Cuneus - basic visual processing

  • Calcarine sulcus/fissure

    • primary visual cortex

    • takes signals from geniculate nucleus via thalamus

Tracts- only for reference

  • Arcuate fasciculus- links Broca’s + Wernicks area

  • Uncinate fasciculus

    • Links temporal inferior frontal gyrus + frontal lobe

    • Hippocampus + amygdala with orbitofrontal cortex

    • implicated in several psych conditions

  • 2 visual streams hypothesis:

    • dorsal - where?

    • ventral- what?

Central dopamine hypothesis

  • Meso-cortical pathway

  • Meso-limbic pathway

  • Nigrostriatal pathway

  • Affected in schizophrenia + other psych disorders

  • Medications for scz work on this pathway

  • Side effects of these meds are linked to these pathways (e.g. cog-wheel rigidity like that seen in parkinson’s/ galactorrhea due to pituitary stimulation)

Alzheimer’s Dementia

  • Microscopic accumulations of peptide amyloid-β – plaques → cause loss of synapses, then neurons.

  • Progressive degeneration

  • Early changes in the hippocampus (first to be damaged)

Generalised shrinking and enlarged ventricles follow

  • In severe depression, the dentate gyrus don’t light up in the scans which means they don’t form many memories.

Drug misuse

  • The reward system is based on dopamine.

  • It activates all dopamine pathways, particularly the mesolimbic pathway.

  • Dopamine is produced in the Vental Tegmental Area (VTA).

  • The mesolimbic pathway links this to the Nucleus Accumbens (motivation/ reward).

  • If we do something good, or use an addictive drug, this pathway is stimulated.

  • The mesocortical pathway is also activated.

  • This links to the Prefrontal Cortex (PFC).

  • This changes how you prioritise and plan.

Disorders

Case 1- depression after frontal tumour

  • 56 year old female

  • Progressive apathy

  • Social withdrawal

  • Poor self-care for part 3 years

  • Admitted to a psychiatric facility for depression

  • unresponsive to antidepressants so CT was conducted

  • 8cm medial bifrontal mass

  • Total excision benign transitional-type meningioma → rapid improvement

  • 4 months after the operation was cheerful + motivated

Case 2- Psychosis after temporal tumour

  • 18-year-old female

  • Referred form school to a psychosis clinic (high risk)

  • 2 years of withdrawal from social activities + resent from work groups or talking in public

  • 1 year later became concerned about unknown people stating + laughing at her for no reason

  • Feeling the world around her has changed

  • She is concerned that people are intimidating her + that there are special messages in TV for her

  • She is neurologically normal + an average IQ

  • Initial diagnosis: prodromal syndrome of schizophrenia but symptoms became more rapidly severe

  • Routine MRI conducted

  • Tumour in the left temporal lobe - dysembryoplastic neuroepithelial tumour (DNET)- usually benign glial neural neoplasm

  • Surgically remove

  • Psychotic symptoms improved with the help of other treatments- risperidone + CBT

  • However, remained socially withdrawn

Case 3- bipolar effective disorder due to Wilsons disease

  • Middle aged female

  • Detained + admitted under section 2 of the Mental Health Act (MHA) 2007- decline in her mental state

  • Initially aggressive behaviour + required restrain by the Emergency Department security + police

  • Quietly spoken

  • voicing paranoid persecutory delusions

  • euthymic with labile affect

  • alternating between anger

  • tearfulness

  • displaying disinhibited affection

  • Doesn’t know why she was presented

  • CT

  • Hypodensity in the putamen, worse on the left

  • No mass, infarct or infectious process to explain the lesions

  • Consistent with the MRI from a couple of months ago which demonstrates hyperintensity of both putamina

  • Associated with Wilson’s disease

  • final diagnosis: psychosis secondary to neurological Wilson’s Disease

Case 4- Psychiatric syndromes associated with neurological disease

  • 63-year-old male

  • paranoia

  • impaired anterograde memory + fatigue

  • FLAIR scan shows bilateral hyperintensities in the hippocampus (arrows) → shows inflammatory process

  • Blood tests revealed anti-voltage gated potassium channel antibodies

robot