frontal and temporal functions

1. Frontal and temporal lobar functions
Dr B Suneel kumar
MD,DM. Consultant Neurophysician .
Q1 hospitals, Health city, Vizag.
18TH REGIONAL SOCIETY OF ANATOMISTS MEET -2019

5. • In humans, the frontal lobe reaches full maturity around the late 20s
(Giedd et al., 1999)

6. The orbitofrontal cortex is divided into ventromedial
(reddish in the anterior view: above and yellow in the
convex-lateral and median-sagittal view) and the
lateral orbitofrontal cortex (green)

7. LATERAL SURFACE OF THE BRAIN
PINK - REGION SUPPLIED BY MIDDLE CEREBRAL ARTERY
BLUE – REGION SUPPLIED BY ANTERIOR CERBRAL ARTERY

9. ACA – MEDIAL SURFACE OF BRAIN

10. Functional regions of the frontal lobes
I. Primary motor area
II. Premotor area
III. Frontal eye fields
IV. Dorsolateral prefrontal cortex
V. Orbital and basal areas
VI. Supplementary motor area and anterior cingulate gyrus area

11. I. Primary motor area
• Pyramidal motor functions
• Although designated a
“motor” cortex, this area is also
involved with somatosensory
perception

12. CORTICAL HOMUNCULUS (Primary motor)
• A cortical homunculus is a pictorial representation of
the anatomical divisions of the primary motor cortex.

13. Primary motor dysfunction
• Initially flacid hemiparesis or hemiplegia
on contralateral side
• Later spastic hemiparesis or
hemiplegia

14. II. Premotor area
• Brodmann area 6
• Integration of sensory and motor
information
• Praxis

15. Premotor dysfunction
• Apraxia
• Preserved postural praxis via basal
ganglia
• Contralateral fine motor deficits
• Difficulty using sensory feedback

16. III. Frontal eye field
• Brodmann area 8 (posterior portion of
middle frontalgyrus), with some area 9
and 6
• Volitional eye movement in
contralateral visual field
• Active visual search

17. Frontal eye field dysfunction
• Failure to move eyes volitionally to
contralateral visual field
• Intact passive eye
movement
• Poor visual search

18. IV. Dorsolateral PFC

19. Dorsolateral PFC dysfunction
• Poor judgement in response
selection
• Impersistence
• Perseveration

20. V. Orbital and Basal areas
• Brodman areas 10,11,12,13,14
• Input from limbic and olfactory systems
(amygdala, temporal pole, entorhinal
cortex, olfactory nerve); inferotemporal
lobe areas, ventral visual pathways
• Output to autonomic musculature and
endocrine system (basal forebrain
cholinergic system, caudate, and
autonomic system)

21. FUNCTIONS OF OFC
• It mediates empathic, civil and socially appropriatebehavior (Mega
and Cummings, 1994).
• Working memory for feature information
• Integration of memory and emotional valence
• Smell discrimination

22. OFC dysfunction
• Disinhibition, socially inappropriate
behavior
• Failure on feature working memory
tasks
• Anosmia
• Confabulation

23. VI. SMA/Cingulate area
• These areas are involved in drive and
motivated behavior initiation and goal-
directed behavior (Devinsky et al, 1995)
• Environmental exploration
• Complex attention

24. Cingulate/SMA dysfunction
• Akinetic mutism occurs with gross lesions (e.g., meningioma) of the
anterior cingulate. Such patients are profoundly apathetic, generally
mute and eat and drink only when assisted.
• Lesions of the supplementary motor area are associated with the
alien hand syndrome (Goldberg & Bloom, 1990).

25. FRONTAL-SUBCORTICAL CIRCUITS
• There are 5 parallel, separate circuits (Alexander et
al, 1986)
A motor circuit.
An oculomotor unit.
Dorsolateral prefrontal circuit, which underpins
executive functions
Anterior cingulate circuit which underpins
motivation
Orbitofrontal circuit which underpins impulse
control and social behavior.
Neurology
Psychiatry

26. The orbitofrontal cortex is divided into ventromedial
(reddish in the anterior view: above and yellow in the
convex-lateral and median-sagittal view) and the
lateral orbitofrontal cortex (green)

27. dorsomedial
Dorsolateral prefrontal
Dorsolateral
caudate
Lateral
dorsomedial
Globus Pallidus
VA & MD
Thalamus
Anterior Cingulate
Nucleus
accumbens
Rostrolateral
Globus Pallidus
MD
Thalamus
Orbital prefrontal
Ventromedial
caudate
Medial
Globus pallidus
VA & MD
Thalamus

28. Temporal lobe

29. • Brodmanm areas on lateral suraface
of Temporal lobe –
- Auditory area (area 41, 42)
- Auditory association cortex (area 22)
- Ventral visual stream areas
( area 20, 21, 37 & 38 )

30. The Medial Temporal region
(LIMBIC CORTEX) includes :-
- Amygdala and adjacent cortex
(Uncus )
- Hippocampus and the
surrounding cortex i.e.
- Subiculum
- Entorhinal Cortex
(Brodmann area 28 )
- Perirhinal Cortex
(Broadmann area 35 &
36 )

31. AMYGDALA
•The amygdala (Latin,meaning
'almond') are almond-shaped groups
of neurons located deep within the
medial temporal lobes of the brain,
in close relation to anterior end of
inferior horn of lateral ventricle

32. Hierarchical sensory pathway
connections from primary and secondary auditory
and visual cortical
through the lateral temporal cortex
terminate in the temporal pole
• Subserves stimulus recognition

34. Polymodal Pathway
• A series of parallel projections from the visual and auditory association
areas into the polymodal regions of the superior temporal sulcus
• Functions in stimulus categorization

35. Dorsal auditory pathway
• Forms important functional connections from auditory areas
to posterior parietal cortex
• Concerned with directing movements with respect to auditory
information

36. Medial Temporal Projection
• Projections from auditory and visual areas into the limbic
regions
E.g., amygdala and hippocampus
• Also called Perforant pathway
• Serves function in long term memory

37. Frontal-lobe
Projection
• Auditory and visual information goes to two prefrontal regions, one on
the dorsolateral surface and the other in the orbital region
• necessary for various aspects of movement control, short- term
memory and affect.

38. Consider an example..
• Imagine that you want to buy a car and now you are riding a two wheeler.
On your ride, you notice many different cars, and you decide to keep a
mental list of the brands and colours that you encounter so that you can
discuss with family and friends later on.
• As you ride along, you suddenly stop and back up—you have
encountered a traffic policeman on the roadside of the next square
walking with a fineslip towards you . You decide to change routes and
look for cars elsewhere!
• What temporal-lobe functions took part in your experience?

39. • To be aware of specific type, colour and brand- object
recognition by ventral visual pathway
• Matching acceleration/engine sound to visual input- Cross modal
matching by dorsal auditory pathway
• Policeman walking towards you- “Biological motion” by superior
temporal sulcus
• On seeing fineslip- increased HR and BP and affective response-
by amygdala
• Toremember all the cars and discuss- medial temporal lobe

40. MEMORY-
Medial temporal lobes
• The MTL is comprised of multiple structures
including the
Hippocampal formation,
Amygdala,
Entorhinal cortex, and
Surrounding perirhinal and parahippocampal cortices
• It has essential role in the formation of new
memories about experienced events
(episodic or autobiographical memory).

41. OTHER FUNCTIONS
• Vestibular functions:
– Some fibers from vestibular input are relayed in superior temporal
gyrus
– Episodic vertigo may represent the aura or sole manifestation of
temporal CPS
• Time perception:
– Main neural mechanism subserving time perception & integrating it
with other sensory inputs and memory lies in temporal lobe
– With disorder of temporal lobe of either side, there may be
intermittent disturbance of time perception

42. Symptoms of Temporal
Lobe Lesions

43. Affect and Personality
• Stimulation of anterior and medial temporal cortex produces feelings of
fear
• Temporal lobe personality
– Personality that overemphasizes trivial details of life
– Pedantic speech (an overly formal speaking style inappropriate to the
conversational setting)
– Proneness to aggression

44. Wernickes Aphasia
• Also known as Fluent / Recepetive / Sensory / Postrolandic Aphasia
• Due to destruction of posterior superior temporal area of the dominant
hemisphere supplied by inferior division of MCA.
– Fluency is preserved with a normal or even increased word
output (LOGORRHEA)
– Speech although effortless is devoid of meaningful content
– Paraphasias, Neologisms and defective sentence structure
(PARAGRAMMATISM) (JARGON APHASIA)
– Auditory comprehension is impaired, even unaware of his own
speech, and doesnot correct himself.
– Patient often is unaware of the defect

45. Temporal lobe epilepsy / psychomotor seizures
visual hallucinations and
perversions.
• Lesions involving medial temporal lobe
in the region of Uncus ( so also k/a
UNCINATE FITS which involve olfactory
hallucination also)
• DÉJÀ VU ( already seen), JAMAIS
VU (something familiar is strange
or new), DEJA PENSEE/ DEJA VACU
( something new seeming strangely
familiar).

46. THANK YOU
Disclosures : no disclosures