.. _ROI_45a:

################
VLPFC (area 45a)
################

VLPFC (area 45a)
Area 45 is found in the caudal aspect of the convexity, back to the inferior limb of
the arcuate sulcus ( :ref:`Walker, 1940 <ref_Walker_1940>` ). Based on the comparative cytoarchitectonic
analysis in both human and nonhuman primates, :ref:`Petrides and Pandya (1999,
2002) <ref_Petrides_1999>` have subdivided this area into 45a and 45b, on the convexity rostral to the
arcuate sulcus and in the rostroventral bank of the sulcus, respectively (see also
:ref:`Gerbella et al., 2010 <ref_Gerbella_2010>`, for the architectonic analysis of these areas ).

.. Images:

******
Images
******

.. figure:: media/45a_right_introduction1.jpg
   :align: center
   :figwidth: 70%

   area 45a histology sections courtesy of `brainmaps.org <http://brainmaps.org/index.php?action=viewslides&datid=1>`_

.. Architectonic_delineation:

*************************
Architectonic delineation
*************************

Area 45a is characterized by the presence of large but less prominent pyramidal
neurons in deeper part of layer III (IIIB; see red arrow-heads in Fig. C on the left);
poorly defined layer II; well developed layer IV; and densely populated small and
medium sized pyramidal neurons in layer V (See also :ref:`Walker, 1940 <ref_Walker_1940>`;
:ref:`Petrides and Pandya, 1999, 2002 <ref_Petrides_1999>`; 
:ref:`Gerbella et al., 2010 <ref_Gerbella_2010>`; 
:ref:`Petrides et al., 2012 <ref_Petrides_2012>` ).

.. Connections:

***********
Connections
***********

**Find more info on Area 45a connections at the following link**

:ref:`Connections Page <ROI_45a_connections>`


.. Intrinsic_connections:

Intrinsic connections
=====================

It is connected with all the subdivisions of the LPFC (VLPFC, DPFC and CLPFC)
networks.


.. Extrinsic_connections:

Extrinsic connections
=====================

The major connections are with auditory related areas in the supratemporal plane
(STP), superior temporal gyrus (core, belt, parabelt, and STGr), and the dorsal
bank of the superior temporal sulcus (STSd; :ref:`Petrides and Pandya 2002 <ref_Petrides_2002>`;
:ref:`Saleem et al., 2008, 2014 <ref_Saleem_2008>`; 
:ref:`Gerbella et al., 2010 <ref_Gerbella_2010>` ).

.. Subcortical_connections:

Subcortical connections
=======================

Thalamus: (:ref:`Contini et al., 2010 <ref_Contini_2010>`)
Claustrum: Area 45a receives projection from rostrocaudal extent of ventral 2/3
of the claustrum (:ref:`Saleem et al., 2014 <ref_Saleem_2013>`; e.g., their Fig. 12).
Striatum: (:ref:`Ferry et al., 2000 <ref_Ferry_2000>`)
Amygdala: Area 45a sends feedforward projections to dorsal subdivision of
lateral nucleus (Ld), magnocellular and intermediate subdivisions of basal
nucleus (Bmc and Bi, respectively). It also receives feedback projections from
magnocellular, parvicelluar, and intermediate subdivisions of the basal nucleus
(Bmc, Bpc, Bi; :ref:`Gerbella et al., 2013 <ref_Gerbella_2013>` ).

.. Functions:

*********
Functions
*********

- Vocal and facial communication between monkeys.
- Recordings that seem to correspond to 45a have found convergent of visual
  and auditory stimuli in individual neurons; the auditory responses were
  particularly to species-specific calls (:ref:`Sugihara et al., 2006 <ref_Sugihara_2006>`;
  :ref:`Romanski, 2012 <ref_Romanski_2012>` ).
- Visual responses to face stimuli have also been found (
  :ref:`Wilson et al., 1993 <ref_Wilson_1993>`;
  :ref:`O'Scalaidhe et al., 1997 <ref_OScalaidhe_1997>`;
  :ref:`Tsao et al., 2008 <ref_Tsao_2008>` ).


.. Homologue:

***********************
Homologue area in human
***********************

Area 45a (also 45b and 44) may be a precursor for the language related areas
found in the caudal ventrolateral prefrontal cortex in humans (
:ref:`Kelly et al., 2010 <ref_Kelly_2010>`;
:ref:`Petrides et al., 2012, 2014 <ref_Petrides_2012>` ).

.. References:

**********
References
**********

.. _ref_Contini_2010:

Contini M, Baccarini M, Borra E, Gerbella M, Rozzi S, Luppino G. 2010.
Thalamic projections to the macaque caudal ventrolateral prefrontal
areas 45A and 45B. Eur J Neurosci 32:1337-1353, 2010. `PubLink1 <http://dx.doi.org/10.1111/j.1460-9568.2010.07390.x>`_

.. _ref_Ferry_2000:

Ferry AT, Ongur D, An X, Price JL. 2000. Prefrontal cortical projections to the
striatum in macaque monkeys: evidence for an organization related
to prefrontal networks. J Comp Neurol 425:447-470. `PubLink2 <http://dx.doi.org/10.1002/1096-9861(20000925)425:3%3C447::AID-CNE9%3E3.0.CO;2-V>`_

.. _ref_Gerbella_2013:

Gerbella M, Baccarini M, Borra E, Rozzi S, Luppino G. 2013. Amygdalar connections
of the macaque areas 45A and 45B. Brain Struct Funct. Mar 26. `PubLink3 <http://dx.doi.org/10.1007/s00429-013-0538-2>`_

.. _ref_Gerbella_2010:

Gerbella M, Belmalih A, Borra E, Rozzi S, Luppino G. 2010. Cortical connections
of the macaque caudal ventrolateral prefrontal areas 45A and 45B.
Cereb Cortex 20:141-168. `PubLink4 <http://dx.doi.org/10.1093/cercor/bhp087>`_

.. _ref_Kelly_2010:

Kelly C, Uddin LQ, Shehzad Z, Margulies DS, Castellanos FX, Milham MP,
Petrides M. 2010. Broca's region: linking human brain functional
connectivity data and non-human primate tracing anatomy studies. Eur J
Neurosci 32:383-398. `PubLink5 <http://dx.doi.org/10.1111/j.1460-9568.2010.07279.x>`_

.. _ref_OScalaidhe_1997:

O'Scalaidhe SP, Wilson FA, Goldman-Rakic PS. 1997. Areal segregation of
face-processing neurons in prefrontal cortex. Science 278:1135-1138.
Petrides M. 2014. Neuroanatomy of language regions of the human brain.
Academic Press, San Diego. `PubLink6 <http://dx.doi.org/10.1126/science.278.5340.1135>`_

.. _ref_Petrides_1999:

Petrides M, Pandya DN. 1999. Dorsolateral prefrontal cortex: comparative
cytoarchitectonic analysis in the human and the macaque brain and
corticocortical connection patterns. Eur J Neurosci 11:1011-1036. `PubLink7 <http://dx.doi.org/10.1046/j.1460-9568.1999.00518.x>`_

.. _ref_Petrides_2002:

Petrides M, Pandya DN. 2002. Comparative cytoarchitectonic analysis of the
human and the macaque ventrolateral prefrontal cortex and corticocortical
connection patterns in the monkey. Eur J Neurosci 16:291-310. `PubLink8 <http://dx.doi.org/10.1046/j.1460-9568.2001.02090.x>`_

.. _ref_Petrides_2012:

Petrides M, Tomaiuolo F, Yeterian EH, Pandya DN. 2012. The prefrontal cortex:
comparative architectonic organization in the human and the
macaque monkey brains. Cortex 48:46-57. `PubLink9 <http://www.sciencedirect.com/science/article/pii/S0010945211002279>`_

.. _ref_Romanski_2012:

Romanski LM. 2012. Integration of faces and vocalizations in ventral prefrontal
cortex: implications for the evolution of audiovisual speech. Proc Natl
Acad Sci U S A 109:10717-10724. `PubLink10 <http://dx.doi.org/10.1073/pnas.1204335109>`_

.. _ref_Saleem_2008:

Saleem KS, Kondo H, Price JL. 2008. Complementary circuits connecting the
orbital and medial prefrontal networks with the temporal, insular, and
opercular cortex in the macaque monkey. J Comp Neurol 506:659-693. `PubLink11 <http://dx.doi.org/10.1002/cne.21577>`_

..  _ref_Saleem_2013:

Saleem KS, Miller B, Price JL. 2013. Subdivisions and connectional networks of
the lateral prefrontal cortex in the macaque monkey. J Comp Neurol
Nov 9 [Epub ahead of print]. `PubLink12 <http://dx.doi.org/10.1002/cne.23498>`_

.. _ref_Sugihara_2006:

Sugihara T, Diltz MD, Averbeck BB, Romanski LM. 2006. Integration of auditory
and visual communication information in the primate ventrolateral prefrontal
cortex. J Neurosci 26:11138-11147. `PubLink13 <http://dx.doi.org/10.1523/JNEUROSCI.3550-06.2006>`_

.. _ref_Tsao_2008:

Tsao DY, Schweers N, Moeller S, Freiwald WA. 2008. Patches of face selective
cortex in the macaque frontal lobe. Nat Neurosci 11:877-879. `PubLink14 <http://www.nature.com/neuro/journal/v11/n8/full/nn.2158.html>`_

.. _ref_Walker_1940:

Walker AE. 1940. A cytoarchitectural study of the prefrontal area of the
macaque monkey. J. Comp Neurol 73:59-86. `PubLink15 <http://dx.doi.org/10.1002/cne.900730106>`_

.. _ref_Wilson_1993:

Wilson FA, Scalaidhe SP, Goldman-Rakic PS. 1993. Dissociation of object and spatial
processing domains in primate prefrontal cortex. Science 260:1955-1958. `Publink16 <http://dx.doi.org/10.1126/science.8316836>`_
